Chemical, nutritive, fermentative and microbial composition of almond hull silage

Selim Sırakaya

doi:10.1080/09712119.2022.2148678

Chemical, nutritive, fermentative and microbial composition of almond hull silage

Sırakaya, Selim 2023-12-31 00:00:00 JOURNAL OF APPLIED ANIMAL RESEARCH 2022, VOL. 51, NO. 1, 17–23 https://doi.org/10.1080/09712119.2022.2148678 Selim Sirakaya Technical Sciences Vocational School, Aksaray University, Aksaray, Turkey ABSTRACT ARTICLE HISTORY Received 18 August 2022 Almond hulls are generally used as feed after drying. In this study, silage was made from almond hulls Accepted 12 November 2022 and quality and feed potential were investigated. In this context, chemical, fermentation, microbiological analyses and digestion–energy calculations were made. The total weight of the KEYWORDS almond fruit was 10.47 ± 1.68 g, the hull weight was 6.56 ± 1.30 g and the percentage of the hull to Almond hull; almond hull the total fruit was 62.48 ± 6.57. In the almond hull silage samples, pH 5.75 ± 0.01, NH –N 112.5 ± 1.45 g silage; silage fermentation −1 −1 −1 −1 kg , lactic acid 63.79 ± 1.83 g kg , acetic acid 22.94 ± 1.93 g kg , propionic acid 28.27 ± 1.45 g kg −1 and butyric acid 9.59 ± 0.88 g kg were determined. Yeast–mould and enterobacter were not −1 detected and the lactic acid bacteria was 4.54 ± 0.04 log cfu g . The most potassium 1212.50 ± 23.90 ppm, calcium 621.36 ± 23.91 ppm and magnesium 586.25 ± 21.43 ppm minerals were found. −1 −1 Crude protein was 92.5 ± 5.9 g kg , crude ash 111.3 ± 1.1 g kg , acid detergent ﬁbre 282.7 ± 2.9 g −1 −1 −1 kg , neutral detergent ﬁbre 394.3 ± 2.7 g kg , total digestible nutrients 521.7 ± 8.5 g kg , metabolic −1 −1 energy 1.85 ± 0.03 mcal kg and net energy lactation 1.11 ± 0.03 mcal kg were determined. It was concluded that although almond hull fermentation properties are partially desirable, they can be stored and used as silage. Introduction about three times as many by-products and the outer hull of The use of alternative sources as feed for proﬁtable and sustain- these products is about twice as much. able livestock is attracting attention and increasing its impor- Almond hull has a major content in terms of structural tance day by day due to reasons such as increasing food carbohydrates such as ADF 32.20% ± 10.69 and NDF 38.66% requirements with the population, increase in feed prices, ± 12.92 (Dairy One 2022), and non-structural carbohydrates climate change and supply-demand imbalance. In this sense, such as glucose, fructose and sucrose (between 25% and 30% the green-looking outer hull, which is one of the by-products in total) (Oﬀeman et al. 2014; Holtman et al. 2015). Alternative obtained after the almond harvest, has been used as feed for feed sources often have high ﬁbre content (Wang et al. 2021), in many years, especially by California farmers. Due to its high this sense, the almond hull is also classiﬁed according to this nutrient content, almond is seen as a valuable food worldwide content. According to the California Department of Food & and the interest in its cultivation is increasing day by day Agriculture, to qualify as an almond hull, it should not (Salgado-Ramos et al. 2022), the amount of by-products contain more than 13% moisture, more than 15% ﬁbre and increases with increasing production and these by-products more than 9% ash (CDFA 2013). According to the unoﬃcial are considered an alternative source for feed and other acceptance in the feed industry, almond hulls are considered sectors (Wang et al. 2021). According to the International Nut prime hulls if their crude ﬁbre content is less than 15% and Dried Fruit Council 2020 report, this increase has been (Swanson et al. 2021). 26% in the last 10 years. Minimization of waste products and Although almond hull is rich in structural and non-struc- evaluation of by-products play a key role in terms of sustain- tural carbohydrates, its protein content (5.95% ± 2.89) is low ability and proper management (Barral-martinez et al. 2021). (Dairy One 2022). A high fermentable carbohydrate content Almond fruit consists of three basic parts: outer hull, inner indicates that it can be used as a substitute for concentrated shell and nut. Approximately 50% of the total fruit consists of feed, and a high NDF ratio indicates that it can be considered the outer hull, 25% of the inner shell and 25% of the nut as a substitute for roughage feed. In this respect, it can be (Aguilar et al. 1984; Fadel 1999; Almond Board Of California considered two-way feed in its ration content. Californian 2018). According to the Almond Board of California data, farmers use almond hulls to reduce the amount of land to 2233 billion kgs of almond hulls were produced in the 2020– be cultivated for silage and to replace some of the silage. 2021 production season and it constitutes 49% of the total Almond hull can be considered as a product that can be fruit weight (Almond Board of California 2021). According to mixed into corn silage due to the similarity of its energy these data, the almond purchased from the nut shop has values with corn silage, its high sugar content, its ﬂavour to CONTACT Selim Sirakaya selimsirakaya@hotmail.com Technical Sciences Vocational School, Aksaray University, Hacılar Harmanı Mah. 12. Bulvar No: 2 Merkez, 68100 Aksaray, Turkey © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, dis- tribution, and reproduction in any medium, provided the original work is properly cited. 18 S. SIRAKAYA the food and its alternative to high-energy feeds (Oliveira amount and percentage of almonds and hulls, randomly 50 2021). almond fruit and hulls were weighed. Almond hull is anatomically similar to the ﬂeshy part of the The cracked outer hulls of the fruit were separated from the peach and is used as a feed raw material in ruminant diets in interior by hand and collected in a container. Almond hulls diﬀerent parts of the world (DePeters et al. 2020). They are were mixed and homogenized and transferred to polyethylene used between 5% and 9% in the ration content of California vacuum bags (Caso Professional Vacum Rolls, Arsberg, dairy cattle farms and some of their needs for other feed Germany) of 30 × 35 cm dimensions as 1 kg in ﬁve replications sources are replaced in this way (Almond Board of California without any processing (chopping, etc.). The air in the poly- 2021) and it can be used safely up to 20% in ruminant diets ethylene vacuum bags containing the sample was evacuated (Swanson et al. 2021). Studies have been carried out in which with a vacuum packaging machine (DZ-260/PD, SELES almond hull is partially used instead of alfalfa in ruminate vacuum package device, Bursa, Turkey) and the mouth of the rations (Reed and Brown 1988; Rad et al. 2016), its eﬀect on bags was closed automatically by heat treatment. The egg quality is examined (Wang et al. 2021) and nutrient con- samples were left to ferment in an oxygen-free environment tents and digestibility values are determined (Jafari et al. in the bags. These bags were stored in the laboratory at an 2015; DePeters et al. 2020; Swanson et al. 2021; Swanson average temperature of 20–25°C for 90 days (1 November–30 et al. 2021). In addition, although studies express that it January). reduces milk yield and dry matter consumption, it is rec- Some of the almond hulls were dried naturally in the ommended to be used in terms of low cost and evaluation of shade, and their nutritional values were also evaluated in the a by-product (Alibés et al. 1983; Williams et al. 2018). Studies study. on the use of almond hulls as feed continue to be carried out by scientists and industry stakeholders. As a result, the almond hull can be dried during and after Organic acid, pH, NH –N analyses harvesting and stored for a long time as a raw material with After the fermentation period (90 days), the sample bags were low moisture content (Jafari et al. 2011). But when stored opened and immediately mixed with distilled water to contain outside, it acts like a sponge, absorbing moisture and a 20% (20 g sample + 80 ml distilled water) sample. The mixture mould grows quickly. When it is damaged by rain, sugar was ﬁltered through ﬁlter papers and the acidity of the ﬁltrate content is lost and feed value decreases (Asmus 2015). In was determined by a pH meter. For organic acid and NH –N this respect, the method of preserving the almond hull as 3 analysis, 40 g of silage sample was shaken vigorously with wet is a diﬀerent issue. Most of the studies on the almond 360 ml distilled water and ﬁltered through the Whatman hull were done on dry material. In the light of this infor- (no:1) ﬁlter paper. For NH –N analysis, 100 ml of ﬁltrate was mation, our hypothesis in this study is that almond hulls 3 taken, put into the Kjeldahl wet burning tube placed in the dis- with a certain moisture content (60–70%) can be preserved tillation device (Gerhardt VAP 20, Königswinter, Germany) and as silage, and in this context, our aim is to evaluate the 32% NaOH was added to it. The distillate was collected in a silage characteristics of almond hulls and their feed potential 50 ml of 2% boric acid solution using a distillation device, as silage. and this distillate was titrated with 0.1 N HCl to determine NH –N (Canpolat 2019). For organic acid analysis, some of these ﬁltrates were stored in screw cap tubes at −20°C until −3 Material and methods the time of analysis (10 days). For lactic acid analysis, a 10 sol- −1 ution was prepared from the 10 ﬁltrate prepared for other Material collection and silage preparation analyses, using distilled water. 0.1 ml of solution was taken In this study, the outer hulls of almond fruit harvested from and 0.1 ml of copper sulphate and 6 ml of concentrated sul- ‘Texas’ variety trees were evaluated (Figure 1). Almonds were phuric acid were added to it and mixed with vortex. Then ′ ′ collected from the orchard in Yazıbaşı Village (38°20 N 35°34 0.1 ml of parahydroxybiphenyl was added to it, after vortexing, E) with an altitude of 1391 m, within the borders of the it was kept in boiling water for 1.5 min and cooled. The absor- Develi district of Kayseri province in Turkey. Almonds were har- bance value was read in the spectrophotometer at 560 nm vested by hand at the end of October 2021. To determine the wavelength. The lactic acid content of the samples was Figure 1. The almond tree, wet almond hull (fresh), silage of almond hull (from left to right). JOURNAL OF APPLIED ANIMAL RESEARCH 19 determined by using the values read at 560 nm wavelength of matter intake (DMI %, body weight of animal), total digesti- BW the standard solutions containing lithium lactate (Canpolat ble nutrients (TDN ), metabolic energy (ME) and net energy 1X 2019). The amount of acetic, propionic and butyric acid was lactation (NEL) values. These parameters were calculated determined by gas chromatography (GC 2010+ Shimadzu Cor- according to the formulas speciﬁed in Nutrient Requirements poration, Kyoto, Japan). of Dairy Cattle (NRC 2001). These formulas are given below. In the formulas below, ‘td’ is truly digestible and ‘PAF’ is the abbreviation of processing adjustment factor. The PAF value was taken as 1. Chemical analyses and calculated values NFC% = 100–() CP + EE + CA + NDF Shade-dried almond hulls, evaluated in their natural state, were ground in a laboratory mill (IKA MF.10, Staufen, Germany) to TDN % = tdNFC + tdCP+() tdFA × 2.25+tdNDF–7 1X pass through a 1 mm sieve and made ready for chemical analy- sis. Almond hull silages were ground after opening the vacuum tdNFC = 0.98 ×(100 − [() NDF − NDICP+ CP + EE + CA] × PAF bags and drying in an oven at 60 °C until they reached a con- [−1.2×(ADICP/CP)] tdCPf = CP , for forage stant weight (∼24 h) and put into ziplock bags for chemical analysis. tdFA = EE − 1,() if EE , 1 less than tdFA = 0 Crude protein (CP) was determined by the DUMAS method (AOAC 2006). This method, burning the sample in the furnace tdNDF = 0.75 ×() NDFn − ADL× 1 − ADL/NDFn × 0.667 , in the device (VELP NDA 701, Usmate Velate, Italy), reduces all () NDFn = NDF − NDICP nitrogen forms in it to elemental nitrogen by converting them to nitrogen oxide gases, and determining the amount of ME Mcal/kg =() 1.01 × DE−0.45, (if EE ≤ 3) nitrogen by the thermal conductivity method, multiplying DE Mcal/kg = tdNFC/100 × 4.2 + tdNDF/100 × 4.2 this amount by the protein factor and determining the 1X crude protein value. Ether extract (EE) analysis was performed + tdCP/100 × 5.6 + FA/100 × 9.4 − 0.3 by the extraction method (ANKOM XT15, Macedon NY, USA) NE Mcal/kg =[0.703 × ME]−0.19, (if EE ≤ 3) and petroleum ether was used as a solvent (AOCS 2004). L Crude ash (CA) analysis was performed by burning the DDM% = 88, 89−() 0, 779 × ADF samples in a 550°C ash furnace (CARBOLITE ELF 11/6, Sheﬃeld, UK) (AOAC 2005). Crude ﬁbre (CF) analysis was DMI % = 120/NDF, (BW : percent of body weight) (BW) carried out based on the detection of the burning part by boiling the defatted samples ﬁrst in sulphuric acid, then in sodium hydroxide solution and ﬁnally burning the remaining Microbiological analyses mass (ISO 6865 2000). Acid detergent ﬁbre (ADF) analysis was −1 As soon as the silage samples were opened, a 10 dilution was performed by boiling the sample in an acid detergent sol- prepared by mixing them with peptone water (10 g sample + ution and neutral detergent ﬁbre (NDF) analysis in a neutral 90 ml peptone water) and microbiological cultivations were detergent solution by determining the amount of remaining made from this dilution using the spread plate technique. In mass. Lignin analysis was carried out by determining the this context, yeast–mould, enterobacteria and lactic acid bac- amount of the remaining samples after ADF analysis treated teria were counted in the samples. The media prepared accord- with concentrated (72%) sulphuric acid for a certain period ing to the manufacturer’s instructions were poured into Petri (3 h) (AOAC 1997, 2022). An ANKOM (Macedon NY, USA) dishes. Potato Dextrose Agar (Merc, Darmstadt, Germany) was analyzer was used for CF–ADF–NDF and lignin analyses. For used as the medium for yeast–mould detection and was incu- acid detergent insoluble protein (ADICP) and neutral deter- bated for 5 days at 25 ± 1°C. For enterobacteria count, Violet gent insoluble protein (NDICP), CP analysis was performed Red Bile Agar W/Glucose (Condalab, Madrid, Spain) medium on the basis of the method given above from the residues was used and incubation was carried out at 37 ± 1°C for 24 h. resulting from ADF and NDF analysis. Starch analysis was MRS Agar (Merc, Darmstadt, Germany) medium was used for determined by the polarimetric method (ISO 10520 1997). the determination of lactic acid bacteria numbers and incu- Total sugar (glucose + fructose + maltose + sucrose) analysis bation was carried out at 37 ± 1°C for 72 h. At the end of the was determined by the HPLC (Agilent, 1260, California, USA) incubation periods, the colony-forming units were counted method. For mineral contents, 0.5 g of samples was taken (using the ‘ImageJ 1.53k’ program public domain) and the into vessel tubes, 10 ml HNO and 2 ml HCl were added and results are shown in the table on a logarithmic basis. 200°C was subjected to 15 min microwave (SPEEDWAVE, Jena, Germany) thawing at 1600 W. After the process, it was cooled to room temperature and the 0.2 µm syringe tip was Statistical analysis ﬁltered, and then the mineral amounts were determined in the ICP-MS (AGILENT 7500, California, USA) device (AOAC Statistics, regarding the study, was performed with Minitab 16.1 2009). software using a completely random one-way analysis of var- Using the data obtained from chemical analysis, digestibility iance (ANOVA) procedure. All data were expressed as mean and energy parameters were calculated. These parameters are and standard deviation (mean ± stdsap) and Tukey’s family non-ﬁbre carbohydrate (NFC), digestible dry matter (DDM), dry error rate test was used to determine the diﬀerence between 20 S. SIRAKAYA Table 1. Fresh amount of almond hull on total fruit (n = 50). Table 3. Mineral composition of the almond hull as fresh and silage, ppm (dry matter basis). Indices Results Indices Fresh almond hull Silage almond hull SEM P Weight of whole fruit, g 10.47 ± 1.68 Weight of hull, g 6.56 ± 1.30 Calcium 532.62 ± 36.73 621.36 ± 23.91 30.99 0.002 Percent of hull, % 62.48 ± 6.57 Magnesium 478.00 ± 16.92 586.25 ± 21.43 19.31 0.000 Potassium 3234.10 ± 90.10 1212.50 ± 23.90 65.90 0.000 Phosphorus <0.03 <0.03 Sulphur 8.15 ± 0.14 11.76 ± 0.18 0.17 0.000 samples. A P value greater than 0.05 was found to be signiﬁcant Sodium 156.82 ± 9.72 165.80 ± 6.63 8.32 0.126 Manganese 3.45 ± 0.03 7.85 ± 0.14 0.10 0.000 for the diﬀerence. Zinc 7.70 ± 0.18 9.14 ± 0.07 0.14 0.000 Iron 8.93 ± 0.08 11.15 ± 0.14 0.12 0.000 Aluminium 8.61 ± 0.12 8.00 ± 0.09 0.11 0.000 Silicon 2.50 ± 0.04 4.41 ± 0.10 0.08 0.000 Results and discussion Copper 13.21 ± 0.71 16.85 ± 0.11 0.10 0.000 Chromium <0.001 <0.001 The weighing results of 50 samples taken randomly from Cobalt <0.005 <0.005 almond fruits to determine the outer hull ratio are given in Nickel 0.31 ± 0.11 0.40 ± 0.11 0.01 0.000 Table 1. The outer hull constitutes an average of 62.48% of Arsenic <0.001 <0.001 Selenium <0.003 <0.003 the total weight. The results of this study diﬀered from other Molybdenum <0.007 <0.007 studies because the fruit was weighed on a wet basis. Some Mercury <0.002 <0.002 studies stated that the amount of outer hull in dry almond fruit is 50% (Aguilar et al. 1984; Fadel 1999), and in some reports, 54% and 49% (Almond Board Of California 2018; Tables 2 and 3. As well as, statistical comparisons are shown Almond Board of California 2021). A review stated that the in the relevant table. Since there was no study in which an fresh hull ratio of almond fruit varies between 35% and 62%, almond hull was evaluated as silage, comparisons were made according to the almond variety (Prgomet et al. 2017). As over the literature results of the almond hull in its natural state. seen in the current and other studies, the ratio of the outer In the present study, the CP value of almond hull silage was −1 hull is at very signiﬁcant levels and the results of the study 92.5 g kg . CP values in studies for almond hull were 51.4– −1 −1 are similar to the literature studies. 48.7 g kg (DePeters et al. 2020), 81.1 g kg (Elahi et al. −1 −1 The chemical and nutritional content of fresh and silaged 2017), 45.0 g kg (Swanson et al. 2021), 64.0 g kg (Williams −1 almond hulls are shown in Table 2. When the results are exam- et al. 2018), 32.7–26.5–32.0–23.2 g kg (Jafari et al. 2011) and −1 ined, it is seen that almond hull silage preserves its nutritional 41.1 g kg (Calixto and Cañellas 1982). Although the CP value when compared to its fresh form. The dry matter content value of an almond hull is low, it has diﬀerent results. In the −1 −1 of both samples was 298.4 and 310.6 g kg of the almond hull current study, the CP (92.5 g kg ) value was higher than the −1 as fresh and silage, respectively. In the literature, the almond literature results. The mean values of CP were 59.5 g kg −1 hull was generally evaluated in its dry form and no data were (Dairy One 2022) and 57.0 g kg (Feedipedia 2022) in two found regarding the dry matter percent of the fresh material. diﬀerent feed libraries open to public access online. The CP After that, the current study will focus on the silage value of value of the almond hull in the present study is similar to the the almond hull. However, the nutritional values of almond CP value of corn silage. In addition, in a study conducted on hulls in the fresh form before silage are also expressed in horses fed with diﬀerent amounts of the almond hull, it was determined that as the almond hull ratio increased, the CP digestion rate decreased (Clutter and Rodiek 1992). Table 2. Chemical & nutritional composition of the almond hull as fresh and −1 The EE value of the silage, which was the subject of the silage, g kg (dry matter basis), unless otherwise stated. −1 study, was determined as 10.4 g kg and it was evaluated Indices Fresh almond hull Silage almond hull SEM P that the ether extract amount was low. In other studies, EE Dry matter 298.4 ± 2.7 310.6 ± 3.3 3.02 0.000 −1 −1 Crude protein 79.6 ± 2.9 92.5 ± 5.9 4.63 0.002 values were 29.6 g kg (Elahi et al. 2017), 37.0 g kg (Williams −1 Ether extract 9.1 ± 1.0 10.4 ± 0.5 0.77 0.025 et al. 2018) and 4.4–9.1–8.4 g kg (Jafari et al. 2011). It can be Crude ash 113.0 ± 1.5 111.3 ± 1.1 1.30 0.077 seen that the results of each study diﬀered from each other, Crude ﬁbre 175.7 ± 2.2 183.4 ± 2.9 6.10 0.081 ADF 267.6 ± 3.8 282.7 ± 2.9 3.40 0.000 and the results of the current study were compatible with the NDF 339.2 ± 3.9 394.3 ± 2.7 3.89 0.000 literature data. ADICP 27.3 ± 0.3 28.7 ± 0.8 0.59 0.005 The average crude ash value of the samples was 111.3 g NDICP 64.2 ± 0.3 74.4 ± 13.9 9.80 0.136 −1 −1 Lignin 111.4 ± 0.9 122.3 ± 4.3 3.13 0.001 kg . In other studies, ash values are 114.8 g kg (Elahi et al. −1 Starch 58.9 ± 0.8 61.6 ± 0.8 0.28 0.001 2017), 59.0 g kg (Swanson et al. 2021), 81.2–86.1–128.3– Total sugar 5.2 ± 0.2 10.1 ± 0.3 0.27 0.000 −1 −1 62.7 g kg (Jafari et al. 2011) and 60.9 g kg (Calixto and NFC 459.1 ± 7.8 391.5 ± 7.2 7.52 0.000 TDN 551.4 ± 3.7 521.7 ± 8.5 6.54 0.000 Cañellas 1982). One report stated that the almond hull 1X DDM 680.5 ± 3.0 668.8 ± 2.3 2.65 0.000 should not contain more than 9.0% ash at a moisture content DMI % 3.54 ± 0.04 3.04 ± 0.03 0.04 0.000 (body weight%) of 13.0% (CDFA 2013). When this criterion is evaluated based ME (Mcal/kg) 1.96 ± 0.01 1.85 ± 0.03 0.03 0.000 NE (Mcal/kg) 1.19 ± 0.01 1.11 ± 0.02 0.02 0.000 on the dry matter, it means that the raw ash value over −1 DM: dry matter, ADF: acid detergent ﬁbre, NDF: neutral detergent ﬁbre, ADICP: 103.5 g kg is not suitable in terms of quality criteria. In the acid detergent insoluble crude protein, NDICP: neutral detergent insoluble current study, the ash value was slightly above the criterion. crude protein, NFC: non-ﬁbre carbohydrate, TDN : total digestible nutrition, 1X Some of the study results meet this criterion and some do DDM: digestible dry matter, DMI: dry matter intake of body weight, ME: metab- olize energy, NE : net enegy lactation, SEM: Standard error means. not. The reason for the high ash value in some studies may L JOURNAL OF APPLIED ANIMAL RESEARCH 21 be the contamination of the soil during the harvesting and reason, both the lignin value and other nutritional values of the drying of almond fruits. However, in the current study, since outer hull may vary, and its quality changes. −1 the almonds were collected by hand, there was no contami- Starch content was determined as 61.6 g kg .Indiﬀerent −1 nation with soil, so the ash value can be considered as an indi- studies, starch contents were determined as 4.4–16.6 g kg −1 cator of high mineral content. (DePeters et al. 2020) and 9.3–26.0 g kg (Dairy One 2022; Fee- −1 The crude ﬁbre ratio in this paper was 183.4 g kg . In other dipedia 2022). In this study, the starch content was found to be −1 studies, the CF value were 129.6–150.7 g kg (DePeters et al. higher than in other studies. The total sugar content of almond −1 −1 −1 2020), 149.0 g kg (Swanson et al. 2021) and 106.0 g kg hull silage was 10.1 g kg . In a study on the almond hull, it was (Calixto and Cañellas 1982). The CF amount in the almond stated that the total sugar content ranged between 18% and −1 hull is not more than 150.0 g kg at 13% moisture, which is 30% (Prgomet et al. 2017), and in another study it ranged an important parameter in terms of quality (CDFA 2013). We between 30.6% and 42.0% (Oﬀeman et al. 2014). The total −1 can correct the value as 172.4 g kg on the basis of dry sugar amount in this study does not comply with the literature. matter. The average CF value was expressed as 191.6 and The reason is not fully understood. In this study, it was thought −1 153.0 g kg in two diﬀerent digital sources where the feed that a low fermentable carbohydrate ratio caused insuﬃcient analysis values are indicated (Dairy One 2022; Feedipedia fermentation quality. However in the literature, it is stated 2022). The CF value of the current study was determined as a that the total sugar content of the almond hull is high, so value close to the quality criteria determined by CDFA. The more studies should be done on this subject. diﬀerence between almond hull results may vary depending The values energy and digestibility were calculated as −1 −1 on the almond type, the amount of foreign matter mixed NFC – 391.5 g kg ; TDN – 521.7 g kg ; DDM – 668.8 g 1X −1 −1 with the almond hull and the adhesion of the inner shell to kg ; DMI – 3.04%; ME – 1.85 Mcal kg and NEL – BW% −1 the inner part of the outer hull in some species. 1.11 Mcal kg . In a similar study, two diﬀerent types of −1 ADF and NDF values for this study were 282.7 and 394.3 g almond hulls were expressed as 672.0–633.1 g kg for NFC, −1 −1 −1 kg , respectively. The study examining the eﬀect of the 694.6–670.0 g kg for TDN and 1.63–1.46 Mcal kg for NEL −1 almond hull used at diﬀerent rates in horse diets showed (DePeters et al. 2020). In other studies, NFC was 640.0 g kg , −1 that the rate of ADF digestion was not aﬀected (Clutter and NEL as 1.6 Mcal kg (Swanson et al. 2021), NFC as 330.0 g −1 −1 Rodiek 1992). In one study (DePeters et al. 2020), ADF and kg and TDN as 555.0 g kg (Alibés et al. 1983). In a table −1 NDF ratios were 133.8–192.6 g kg for one variety and with more almond hull analysis results, TDN and NEL are −1 −1 −1 158.9–220.7 g kg for another variety, respectively. In other 582.9 g kg and 1.33 Mcal kg , respectively (Dairy One −1 studies, ADF and NDF were 296.6–598.3 g kg (Elahi et al. 2022). The results are partially similar to the literature data. −1 2017), 149.0–238.0 g kg (Swanson et al. 2021) and 436.0– This is due to the nutrient content that varies due to diﬀerent −1 508.0 g kg (Williams et al. 2018). In a study in which the reasons. hulls of four diﬀerent almond varieties were evaluated, it was In the present study, the mineral contents of the almond stated that the ADF value ranged between 188.3 and 252.2 g hull as fresh and silage are given in Table 3. The order of −1 −1 kg , and the NDF value between 280.5 and 326.4 g kg mineral content (ppm) of almond hull silage was found as K (Jafari et al. 2011). It can be seen that the results diﬀer consider- >Ca>Mg >Na>Cu >S>Fe>Zn >Al>Mn >Si>Ni >P>Mo ably from each other. ADF and NDF values were low in some > Co > Se > Hg > Cr,As. The maximum amount of K was studies and high in some studies. The results of current and 1212.50 ppm, followed by Ca and Mg with 621.36 and other studies show that the quality of the almond hull as 586.25 ppm, respectively. In another study, the highest feed can be highly variable. The variability in these values mineral content of 2880 and 3450 ppm K was determined in also leads to the variability of the digestion rate. two diﬀerent types of almond hulls (DePeters et al. 2020). In ADICP and NDICP analysis results to determine the amount diﬀerent studies, the highest K was determined as 2500 ppm of nitrogen bound to cell wall components were 28.7 and (Swanson et al. 2021) and 3370 ppm (Alibés et al. 1983). In −1 74.4 g kg , respectively. No other study was found in which this study, as in other studies, signiﬁcant levels of K were these values were determined in the almond hull. However, detected in almond hulls. The high amount of K and its simi- in an open-access online feed library, the ADICP and NDICP larity to alfalfa may be a limiting factor in the transition −1 values for the almond hull are 18.5 and 23.0 g kg , respectively period nutrition of cows. When the K values in this study and (Dairy One 2022). In the present study, the results were higher the literature are examined, the possibility of the almond hull than these values. It is considered that this is a diﬀerence due to and silage increasing the cationicity of the diet should be con- the internal heating of the products, depending on the storage sidered and the possibility that it may increase the risk of post- conditions. partum milk fever should be evaluated. Ca and Mg values were −1 The lignin value was 122.3 g kg . The value of lignin in 621.36 and 586.25 ppm, respectively. In the literature, Ca −1 other studies: 76.3–86.9 g kg for two diﬀerent varieties (DeP- (190.00–240.00 ppm) and Mg (90.00–110 ppm) were deter- −1 eters et al. 2020), 72.0 g kg (Swanson et al. 2021) and 122.5– mined for two diﬀerent types of almond hulls (DePeters et al. −1 107.0 g kg in two diﬀerent feed libraries that provide online 2020), while in other studies Ca and Mg were 1080.00 and access (Dairy One 2022; Feedipedia 2022). The variability of 220 ppm (Alibés et al. 1983) and Ca as 370.00 ppm (Jafari lignin value can be evaluated as the adhesion of the inner et al. 2011), respectively. It has been observed that the heavy shell to the inner surface of the outer hull in some almond metal contents are below the risky levels. Although the species. In some cases, the inner shell, which has a woody struc- results in the literature and the results in the current study ture, cannot be completely cleaned from the outer hull. For this are diﬀerent, the proportional amounts of minerals in the 22 S. SIRAKAYA −1 Table 4. Microbiological values of almond hull silage, log cfu g . However, these results were compared with the values that Indices Results should be in legume silages with <30–35% dry matter (lactic Yeast Not detected acid: 60.0–80.0, acetic acid: 20.0–30.0, propionic acid: <5, −1 Mould Not detected butyric acid: <5 g kg ) (Kung et al. 2018). The amounts of Enterobacteria Not detected lactic and acetic acid were determined at the desired level, Lactic acid bacteria 4.54 ± 0.04 while the amounts of propionic and butyric acids were deter- mined in undesired amounts. According to the ﬂeig scoring, in which the silage quality is determined, the percentage distri- almond hull are similar and most K, Ca and Mg minerals are bution of lactic, acetic and butyric acid amounts in the total found in the hull. amount, almond hull silage is in the satisfactory silage quality Nutrient variations in almond hulls may due to the type of group (Canpolat 2019). The presence of high amounts (>5.0 g almond and the region where it grows, soil and climate, etc. −1 kg ) of propionic and butyric acids can often be an indication The degree of purity, cleanliness and mixing ratio of the inner of clostridial activity. Some clostridia bacteria have the ability shell to the outer hull of the hulls should also be considered to convert sugar to butyric acid, and some to convert lactic as another reason for the variation in results. acid to butyric acid. This causes the pH level to be higher than Almond hull silage microbiological analyses are given in expected (Kung et al. 2018). An increase in the amount of propio- Table 4. As a result, yeast–mould and enterobacteria were nic and butyric acids may have occurred with the use of the small not detected in the samples. The number of lactic acid bacteria −1 amount of sugar in the almond hull in the current study by clos- was 4.54 log cfu g . The absence of yeast–mould and entero- tridium. In the current study, acidity did not develop suﬃciently bacteria is a positive situation in terms of silage quality. Signiﬁ- and it does not bring the microbial ﬂora and the organic acid cant proliferation of lactic acid bacteria is considered to have a proﬁle to the desired level. positive eﬀect on the quality of almond hull silage but the Although it is not exactly similar to this study, in another study, silage acidity and organic acid results stated below do not it was mentioned that value-added products can be produced by support this situation suﬃciently. In terms of microbiology, the fermentation of almond hulls. In this context, 0.55–0.47–0.37 g there is no similar data or literature study related to the −1 g of lactic acid was produced from almond hulls with diﬀerent almond hull and its silage. sugar content in the range of 5.5 < pH < 6.0 (Thomas et al. 2019). The results of pH, NH –N, lactic acid, acetic acid, propionic The fermentation pH value in this study is consistent with the pH acid and butyric acid for evaluating the fermentation proﬁle value measured in the current study. are listed in Table 5. The average pH value of almond hull According to the results of a feed analysis table, which is silage samples was 5.75 ± 0.01 and no similar study data were expressed as ‘almond hull wet’ and shows that the DM ratio found in the literature. However, in the open-access feed varies between 76.03% and 87.27%, the amounts of aﬂatoxin library resource, the pH of the almond hull is 5.10. It was men- B1 and aﬂatoxin G1 are 0.587 and 0.237 ppm, respectively tioned that the target pH level should be 4.30–5.00 in legume (Dairy One 2022). These results show that there may be a risk silages and the buﬀering eﬀect of the high crude ash value of mycotoxins in almond hulls depending on storage con- (Kung et al. 2018). In the current study, the pH value could ditions and humidity. To prevent the mycotoxin formation in not be determined at the desired levels. It is considered that the fresh almond shell, making silage or adding it to silages this may be due to the buﬀering eﬀect of the high ash such as corn silage may be important. content of almond hull silage and the lower-than-expected −1 total sugar content. The NH –N value was 112.5 ± 1.45 g kg . No data were found related to this value studied in the Conclusion almond hull and its silage. In a review study, it was stated Many of the by-products that can not be consumed by humans that the NH –N value of legume silage should be between −1 are beneﬁcial for cows. In this sense, almond hulls are already 100.0 and 150.0 g kg (Kung et al. 2018). Since the NH –N consumed by cows. However, in this study, the feed value value was within the recommended range, it was evaluated was determined by making a silage of almond hull. In this that there was no signiﬁcant degradation in the protein struc- paper, almond hull silage was found to be of medium quality, ture of the almond hull in the silage process. In terms of organic −1 and this is considered to be due to the low fermentable carbo- acid proﬁle, the amount of lactic acid is 63.79 ± 1.83 g kg , −1 hydrate content of the almond hulls used in the study. acetic acid is 22.94 ± 1.93 g kg , propionic acid is 28.27 g −1 −1 However, there is information in the literature indicating that kg ± 1.01 and butyric acid is 9.59 ± 0.88 g kg . No data the fermentable carbohydrate content of the almond hull is could be found in the sources to compare organic acid results. higher. As a result, the almond hull can be stored as silage while it has the appropriate moisture content, in conditions where it is not possible to dry or when it is desired to be Table 5. Organic acid, pH and ammonia nitrogen values of almond hull silage, g −1 kg (dry matter basis). stored by leaving it to fermentation. It is recommended to Indices Results conduct more detailed (in vivo, in vitro) and diﬀerent studies pH 5.75 ± 0.01 to support the results of this study and other studies. NH –N 112.5 ± 1.45 Lactic acid 63.79 ± 1.83 Acetic acid 22.94 ± 1.93 Disclosure statement Propionic acid 28.27 ± 1.01 Butyric acid 9.59 ± 0.88 No potential conﬂict of interest was reported by the author(s). JOURNAL OF APPLIED ANIMAL RESEARCH 23 Fadel JG. 1999. Quantitative analyses of selected plant by-product feed- Data availability statement stuﬀs, a global perspective. Anim Feed Sci Technol. 79(4):255–268. The data that support this study will be shared upon reasonable request to Feedipedia. 2022. Almond hulls and almond by-products. Anim Feed the corresponding author. Resour Inf Syst. https://www.feedipedia.org/node/27. Holtman KM, Oﬀeman RD, Franqui-Villanueva D, Bayati AK, Orts WJ. 2015. Countercurrent extraction of soluble sugars from almond hulls and assessment of the bioenergy potential. J Agric Food Chem. 63 ORCID (9):2490–2498. Selim Sirakaya http://orcid.org/0000-0003-2733-1726 ISO 10520. 1997. Native starch - Determination of starch content - Ewers polarimetric method. Int Stand Organ. ISO 6865. 2000. Animal feeding stuﬀs - Determination of crude ﬁbre content - Method with intermediate ﬁltration. Int Stand Organ References [Internet]. www.iso.org. Jafari S, Alizadeh A, Imani A. 2011. Nutritive value of diﬀerent varieties of Aguilar AA, Smith NE, Baldwin RL. 1984. Nutritional value of almond hulls almond (Prunus dulcis) hulls. Res Opin Anim Vet Sci. 1(11):734–738. for dairy cows. J Dairy Sci. 67(1):97–103. Jafari S, Alizadeh A, Imani A, Meng GY, Rajion MA, Ebrahimi M. 2015. In situ Alibés X, Maestre MR, Muñoz F, Combellas J, Rodriguez J. 1983. Nutritive degradation of almond (Prunus dulcis L.) hulls, a potential feed material value of almond hulls for sheep. Anim Feed Sci Technol. 8(1):63–67. for ruminants. Turkish J Vet Anim Sci. 39(6):676–681. Almond Board of California. 2018. Almond tree fruit weight [Internet]. Kung L, Shaver RD, Grant RJ, Schmidt RJ. 2018. Silage review: interpretation [place unknown]. https://www.almonds.com/sites/default/ﬁles/2020- of chemical, microbial, and organoleptic components of silages. J Dairy 04/17-18_almond tree fruit weight.pdf. Sci. 101(5):4020–4033. doi: 10.3168/jds.2017-13909. Almond Board of California. 2021. Almond Almanac [Internet]. [place NRC. 2001. Nutrient requirements of dairy cattle. seventh Re. Washington, unknown]. http://www.almonds.com/sites/default/ﬁles/content/ DC: National Academy Press. attachments/2013_almanac_-_ﬁnal.pdf. Oﬀeman RD, Holtman KM, Covello KM, Orts WJ. 2014. Almond hulls as a bio- AOAC. 1997. Fiber (acid detergent) and lignin in animal feed 973.18. 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Rad MI, Rouzbehan Y, Rezaei J. 2016.Eﬀect of dietary replacement of alfalfa AOAC. 2022. Amylase-treated neutral detergent ﬁber in feeds 2002-4. AOAC with urea-treated almond hulls on intake, growth, digestibility, microbial Oﬀ Method. nitrogen, nitrogen retention, ruminal fermentation, and blood par- AOCS. 2004. Rapid determination of oil/fat utilizing high temperature ameters in fattening lambs. J Anim Sci. 94(1):349–358. solvent extraction. American Oil Chemists’ Society. Reed BA, Brown DL. 1988. Almond hulls in diets for lactating goats: eﬀects Asmus J.. 2015. Nutritionist perspective on almond hulls as a feed on yield and composition of milk, feed intake, and digestibility. J Dairy ingredient..July 2015 Almond Hullers Educational Seminar. CGFA, Sci. 71(2):530–533. Sacramento, USA. Salgado-Ramos M, Martí-Quijal FJ, Huertas-Alonso AJ, Sánchez-Verdú MP, Barral-Martinez M, Fraga-Corral M, Garcia-Perez P, Simal-Gandara J, Prieto Barba FJ, Moreno A. 2022. 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Williams SRO, Chaves AV, Deighton MH, Jacobs JL, Hannah MC, Ribaux BE, Elahi MY, Kargar H, Dindarlou MS, Kholif AE, Elghandour MMY, Rojas- Morris GL, Wales WJ, Moate PJ. 2018.Inﬂuence of feeding supplements Hernández S, Odongo NE, Salem AZM. 2017. The chemical composition of almond hulls and ensiled citrus pulp on the milk production, milk and in vitro digestibility evaluation of almond tree (Prunus dulcis composition, and methane emissions of dairy cows. J Dairy Sci. 101 D. A. Webb syn. Prunus amygdalus; var. Shokoufeh) leaves versus hulls and (3):2072–2083. doi:10.3168/jds.2017-13440. green versus dry leaves as feed for ruminants. Agrofor Syst. 91(4):773–780. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Applied Animal Research Taylor & Francis http://www.deepdyve.com/lp/taylor-francis/chemical-nutritive-fermentative-and-microbial-composition-of-almond-tCp5xFMyb0

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Publisher: Taylor & Francis
Copyright: © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group
ISSN: 0974-1844
eISSN: 0971-2119
DOI: 10.1080/09712119.2022.2148678
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Abstract

JOURNAL OF APPLIED ANIMAL RESEARCH 2022, VOL. 51, NO. 1, 17–23 https://doi.org/10.1080/09712119.2022.2148678 Selim Sirakaya Technical Sciences Vocational School, Aksaray University, Aksaray, Turkey ABSTRACT ARTICLE HISTORY Received 18 August 2022 Almond hulls are generally used as feed after drying. In this study, silage was made from almond hulls Accepted 12 November 2022 and quality and feed potential were investigated. In this context, chemical, fermentation, microbiological analyses and digestion–energy calculations were made. The total weight of the KEYWORDS almond fruit was 10.47 ± 1.68 g, the hull weight was 6.56 ± 1.30 g and the percentage of the hull to Almond hull; almond hull the total fruit was 62.48 ± 6.57. In the almond hull silage samples, pH 5.75 ± 0.01, NH –N 112.5 ± 1.45 g silage; silage fermentation −1 −1 −1 −1 kg , lactic acid 63.79 ± 1.83 g kg , acetic acid 22.94 ± 1.93 g kg , propionic acid 28.27 ± 1.45 g kg −1 and butyric acid 9.59 ± 0.88 g kg were determined. Yeast–mould and enterobacter were not −1 detected and the lactic acid bacteria was 4.54 ± 0.04 log cfu g . The most potassium 1212.50 ± 23.90 ppm, calcium 621.36 ± 23.91 ppm and magnesium 586.25 ± 21.43 ppm minerals were found. −1 −1 Crude protein was 92.5 ± 5.9 g kg , crude ash 111.3 ± 1.1 g kg , acid detergent ﬁbre 282.7 ± 2.9 g −1 −1 −1 kg , neutral detergent ﬁbre 394.3 ± 2.7 g kg , total digestible nutrients 521.7 ± 8.5 g kg , metabolic −1 −1 energy 1.85 ± 0.03 mcal kg and net energy lactation 1.11 ± 0.03 mcal kg were determined. It was concluded that although almond hull fermentation properties are partially desirable, they can be stored and used as silage. Introduction about three times as many by-products and the outer hull of The use of alternative sources as feed for proﬁtable and sustain- these products is about twice as much. able livestock is attracting attention and increasing its impor- Almond hull has a major content in terms of structural tance day by day due to reasons such as increasing food carbohydrates such as ADF 32.20% ± 10.69 and NDF 38.66% requirements with the population, increase in feed prices, ± 12.92 (Dairy One 2022), and non-structural carbohydrates climate change and supply-demand imbalance. In this sense, such as glucose, fructose and sucrose (between 25% and 30% the green-looking outer hull, which is one of the by-products in total) (Oﬀeman et al. 2014; Holtman et al. 2015). Alternative obtained after the almond harvest, has been used as feed for feed sources often have high ﬁbre content (Wang et al. 2021), in many years, especially by California farmers. Due to its high this sense, the almond hull is also classiﬁed according to this nutrient content, almond is seen as a valuable food worldwide content. According to the California Department of Food & and the interest in its cultivation is increasing day by day Agriculture, to qualify as an almond hull, it should not (Salgado-Ramos et al. 2022), the amount of by-products contain more than 13% moisture, more than 15% ﬁbre and increases with increasing production and these by-products more than 9% ash (CDFA 2013). According to the unoﬃcial are considered an alternative source for feed and other acceptance in the feed industry, almond hulls are considered sectors (Wang et al. 2021). According to the International Nut prime hulls if their crude ﬁbre content is less than 15% and Dried Fruit Council 2020 report, this increase has been (Swanson et al. 2021). 26% in the last 10 years. Minimization of waste products and Although almond hull is rich in structural and non-struc- evaluation of by-products play a key role in terms of sustain- tural carbohydrates, its protein content (5.95% ± 2.89) is low ability and proper management (Barral-martinez et al. 2021). (Dairy One 2022). A high fermentable carbohydrate content Almond fruit consists of three basic parts: outer hull, inner indicates that it can be used as a substitute for concentrated shell and nut. Approximately 50% of the total fruit consists of feed, and a high NDF ratio indicates that it can be considered the outer hull, 25% of the inner shell and 25% of the nut as a substitute for roughage feed. In this respect, it can be (Aguilar et al. 1984; Fadel 1999; Almond Board Of California considered two-way feed in its ration content. Californian 2018). According to the Almond Board of California data, farmers use almond hulls to reduce the amount of land to 2233 billion kgs of almond hulls were produced in the 2020– be cultivated for silage and to replace some of the silage. 2021 production season and it constitutes 49% of the total Almond hull can be considered as a product that can be fruit weight (Almond Board of California 2021). According to mixed into corn silage due to the similarity of its energy these data, the almond purchased from the nut shop has values with corn silage, its high sugar content, its ﬂavour to CONTACT Selim Sirakaya selimsirakaya@hotmail.com Technical Sciences Vocational School, Aksaray University, Hacılar Harmanı Mah. 12. Bulvar No: 2 Merkez, 68100 Aksaray, Turkey © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, dis- tribution, and reproduction in any medium, provided the original work is properly cited. 18 S. SIRAKAYA the food and its alternative to high-energy feeds (Oliveira amount and percentage of almonds and hulls, randomly 50 2021). almond fruit and hulls were weighed. Almond hull is anatomically similar to the ﬂeshy part of the The cracked outer hulls of the fruit were separated from the peach and is used as a feed raw material in ruminant diets in interior by hand and collected in a container. Almond hulls diﬀerent parts of the world (DePeters et al. 2020). They are were mixed and homogenized and transferred to polyethylene used between 5% and 9% in the ration content of California vacuum bags (Caso Professional Vacum Rolls, Arsberg, dairy cattle farms and some of their needs for other feed Germany) of 30 × 35 cm dimensions as 1 kg in ﬁve replications sources are replaced in this way (Almond Board of California without any processing (chopping, etc.). The air in the poly- 2021) and it can be used safely up to 20% in ruminant diets ethylene vacuum bags containing the sample was evacuated (Swanson et al. 2021). Studies have been carried out in which with a vacuum packaging machine (DZ-260/PD, SELES almond hull is partially used instead of alfalfa in ruminate vacuum package device, Bursa, Turkey) and the mouth of the rations (Reed and Brown 1988; Rad et al. 2016), its eﬀect on bags was closed automatically by heat treatment. The egg quality is examined (Wang et al. 2021) and nutrient con- samples were left to ferment in an oxygen-free environment tents and digestibility values are determined (Jafari et al. in the bags. These bags were stored in the laboratory at an 2015; DePeters et al. 2020; Swanson et al. 2021; Swanson average temperature of 20–25°C for 90 days (1 November–30 et al. 2021). In addition, although studies express that it January). reduces milk yield and dry matter consumption, it is rec- Some of the almond hulls were dried naturally in the ommended to be used in terms of low cost and evaluation of shade, and their nutritional values were also evaluated in the a by-product (Alibés et al. 1983; Williams et al. 2018). Studies study. on the use of almond hulls as feed continue to be carried out by scientists and industry stakeholders. As a result, the almond hull can be dried during and after Organic acid, pH, NH –N analyses harvesting and stored for a long time as a raw material with After the fermentation period (90 days), the sample bags were low moisture content (Jafari et al. 2011). But when stored opened and immediately mixed with distilled water to contain outside, it acts like a sponge, absorbing moisture and a 20% (20 g sample + 80 ml distilled water) sample. The mixture mould grows quickly. When it is damaged by rain, sugar was ﬁltered through ﬁlter papers and the acidity of the ﬁltrate content is lost and feed value decreases (Asmus 2015). In was determined by a pH meter. For organic acid and NH –N this respect, the method of preserving the almond hull as 3 analysis, 40 g of silage sample was shaken vigorously with wet is a diﬀerent issue. Most of the studies on the almond 360 ml distilled water and ﬁltered through the Whatman hull were done on dry material. In the light of this infor- (no:1) ﬁlter paper. For NH –N analysis, 100 ml of ﬁltrate was mation, our hypothesis in this study is that almond hulls 3 taken, put into the Kjeldahl wet burning tube placed in the dis- with a certain moisture content (60–70%) can be preserved tillation device (Gerhardt VAP 20, Königswinter, Germany) and as silage, and in this context, our aim is to evaluate the 32% NaOH was added to it. The distillate was collected in a silage characteristics of almond hulls and their feed potential 50 ml of 2% boric acid solution using a distillation device, as silage. and this distillate was titrated with 0.1 N HCl to determine NH –N (Canpolat 2019). For organic acid analysis, some of these ﬁltrates were stored in screw cap tubes at −20°C until −3 Material and methods the time of analysis (10 days). For lactic acid analysis, a 10 sol- −1 ution was prepared from the 10 ﬁltrate prepared for other Material collection and silage preparation analyses, using distilled water. 0.1 ml of solution was taken In this study, the outer hulls of almond fruit harvested from and 0.1 ml of copper sulphate and 6 ml of concentrated sul- ‘Texas’ variety trees were evaluated (Figure 1). Almonds were phuric acid were added to it and mixed with vortex. Then ′ ′ collected from the orchard in Yazıbaşı Village (38°20 N 35°34 0.1 ml of parahydroxybiphenyl was added to it, after vortexing, E) with an altitude of 1391 m, within the borders of the it was kept in boiling water for 1.5 min and cooled. The absor- Develi district of Kayseri province in Turkey. Almonds were har- bance value was read in the spectrophotometer at 560 nm vested by hand at the end of October 2021. To determine the wavelength. The lactic acid content of the samples was Figure 1. The almond tree, wet almond hull (fresh), silage of almond hull (from left to right). JOURNAL OF APPLIED ANIMAL RESEARCH 19 determined by using the values read at 560 nm wavelength of matter intake (DMI %, body weight of animal), total digesti- BW the standard solutions containing lithium lactate (Canpolat ble nutrients (TDN ), metabolic energy (ME) and net energy 1X 2019). The amount of acetic, propionic and butyric acid was lactation (NEL) values. These parameters were calculated determined by gas chromatography (GC 2010+ Shimadzu Cor- according to the formulas speciﬁed in Nutrient Requirements poration, Kyoto, Japan). of Dairy Cattle (NRC 2001). These formulas are given below. In the formulas below, ‘td’ is truly digestible and ‘PAF’ is the abbreviation of processing adjustment factor. The PAF value was taken as 1. Chemical analyses and calculated values NFC% = 100–() CP + EE + CA + NDF Shade-dried almond hulls, evaluated in their natural state, were ground in a laboratory mill (IKA MF.10, Staufen, Germany) to TDN % = tdNFC + tdCP+() tdFA × 2.25+tdNDF–7 1X pass through a 1 mm sieve and made ready for chemical analy- sis. Almond hull silages were ground after opening the vacuum tdNFC = 0.98 ×(100 − [() NDF − NDICP+ CP + EE + CA] × PAF bags and drying in an oven at 60 °C until they reached a con- [−1.2×(ADICP/CP)] tdCPf = CP , for forage stant weight (∼24 h) and put into ziplock bags for chemical analysis. tdFA = EE − 1,() if EE , 1 less than tdFA = 0 Crude protein (CP) was determined by the DUMAS method (AOAC 2006). This method, burning the sample in the furnace tdNDF = 0.75 ×() NDFn − ADL× 1 − ADL/NDFn × 0.667 , in the device (VELP NDA 701, Usmate Velate, Italy), reduces all () NDFn = NDF − NDICP nitrogen forms in it to elemental nitrogen by converting them to nitrogen oxide gases, and determining the amount of ME Mcal/kg =() 1.01 × DE−0.45, (if EE ≤ 3) nitrogen by the thermal conductivity method, multiplying DE Mcal/kg = tdNFC/100 × 4.2 + tdNDF/100 × 4.2 this amount by the protein factor and determining the 1X crude protein value. Ether extract (EE) analysis was performed + tdCP/100 × 5.6 + FA/100 × 9.4 − 0.3 by the extraction method (ANKOM XT15, Macedon NY, USA) NE Mcal/kg =[0.703 × ME]−0.19, (if EE ≤ 3) and petroleum ether was used as a solvent (AOCS 2004). L Crude ash (CA) analysis was performed by burning the DDM% = 88, 89−() 0, 779 × ADF samples in a 550°C ash furnace (CARBOLITE ELF 11/6, Sheﬃeld, UK) (AOAC 2005). Crude ﬁbre (CF) analysis was DMI % = 120/NDF, (BW : percent of body weight) (BW) carried out based on the detection of the burning part by boiling the defatted samples ﬁrst in sulphuric acid, then in sodium hydroxide solution and ﬁnally burning the remaining Microbiological analyses mass (ISO 6865 2000). Acid detergent ﬁbre (ADF) analysis was −1 As soon as the silage samples were opened, a 10 dilution was performed by boiling the sample in an acid detergent sol- prepared by mixing them with peptone water (10 g sample + ution and neutral detergent ﬁbre (NDF) analysis in a neutral 90 ml peptone water) and microbiological cultivations were detergent solution by determining the amount of remaining made from this dilution using the spread plate technique. In mass. Lignin analysis was carried out by determining the this context, yeast–mould, enterobacteria and lactic acid bac- amount of the remaining samples after ADF analysis treated teria were counted in the samples. The media prepared accord- with concentrated (72%) sulphuric acid for a certain period ing to the manufacturer’s instructions were poured into Petri (3 h) (AOAC 1997, 2022). An ANKOM (Macedon NY, USA) dishes. Potato Dextrose Agar (Merc, Darmstadt, Germany) was analyzer was used for CF–ADF–NDF and lignin analyses. For used as the medium for yeast–mould detection and was incu- acid detergent insoluble protein (ADICP) and neutral deter- bated for 5 days at 25 ± 1°C. For enterobacteria count, Violet gent insoluble protein (NDICP), CP analysis was performed Red Bile Agar W/Glucose (Condalab, Madrid, Spain) medium on the basis of the method given above from the residues was used and incubation was carried out at 37 ± 1°C for 24 h. resulting from ADF and NDF analysis. Starch analysis was MRS Agar (Merc, Darmstadt, Germany) medium was used for determined by the polarimetric method (ISO 10520 1997). the determination of lactic acid bacteria numbers and incu- Total sugar (glucose + fructose + maltose + sucrose) analysis bation was carried out at 37 ± 1°C for 72 h. At the end of the was determined by the HPLC (Agilent, 1260, California, USA) incubation periods, the colony-forming units were counted method. For mineral contents, 0.5 g of samples was taken (using the ‘ImageJ 1.53k’ program public domain) and the into vessel tubes, 10 ml HNO and 2 ml HCl were added and results are shown in the table on a logarithmic basis. 200°C was subjected to 15 min microwave (SPEEDWAVE, Jena, Germany) thawing at 1600 W. After the process, it was cooled to room temperature and the 0.2 µm syringe tip was Statistical analysis ﬁltered, and then the mineral amounts were determined in the ICP-MS (AGILENT 7500, California, USA) device (AOAC Statistics, regarding the study, was performed with Minitab 16.1 2009). software using a completely random one-way analysis of var- Using the data obtained from chemical analysis, digestibility iance (ANOVA) procedure. All data were expressed as mean and energy parameters were calculated. These parameters are and standard deviation (mean ± stdsap) and Tukey’s family non-ﬁbre carbohydrate (NFC), digestible dry matter (DDM), dry error rate test was used to determine the diﬀerence between 20 S. SIRAKAYA Table 1. Fresh amount of almond hull on total fruit (n = 50). Table 3. Mineral composition of the almond hull as fresh and silage, ppm (dry matter basis). Indices Results Indices Fresh almond hull Silage almond hull SEM P Weight of whole fruit, g 10.47 ± 1.68 Weight of hull, g 6.56 ± 1.30 Calcium 532.62 ± 36.73 621.36 ± 23.91 30.99 0.002 Percent of hull, % 62.48 ± 6.57 Magnesium 478.00 ± 16.92 586.25 ± 21.43 19.31 0.000 Potassium 3234.10 ± 90.10 1212.50 ± 23.90 65.90 0.000 Phosphorus <0.03 <0.03 Sulphur 8.15 ± 0.14 11.76 ± 0.18 0.17 0.000 samples. A P value greater than 0.05 was found to be signiﬁcant Sodium 156.82 ± 9.72 165.80 ± 6.63 8.32 0.126 Manganese 3.45 ± 0.03 7.85 ± 0.14 0.10 0.000 for the diﬀerence. Zinc 7.70 ± 0.18 9.14 ± 0.07 0.14 0.000 Iron 8.93 ± 0.08 11.15 ± 0.14 0.12 0.000 Aluminium 8.61 ± 0.12 8.00 ± 0.09 0.11 0.000 Silicon 2.50 ± 0.04 4.41 ± 0.10 0.08 0.000 Results and discussion Copper 13.21 ± 0.71 16.85 ± 0.11 0.10 0.000 Chromium <0.001 <0.001 The weighing results of 50 samples taken randomly from Cobalt <0.005 <0.005 almond fruits to determine the outer hull ratio are given in Nickel 0.31 ± 0.11 0.40 ± 0.11 0.01 0.000 Table 1. The outer hull constitutes an average of 62.48% of Arsenic <0.001 <0.001 Selenium <0.003 <0.003 the total weight. The results of this study diﬀered from other Molybdenum <0.007 <0.007 studies because the fruit was weighed on a wet basis. Some Mercury <0.002 <0.002 studies stated that the amount of outer hull in dry almond fruit is 50% (Aguilar et al. 1984; Fadel 1999), and in some reports, 54% and 49% (Almond Board Of California 2018; Tables 2 and 3. As well as, statistical comparisons are shown Almond Board of California 2021). A review stated that the in the relevant table. Since there was no study in which an fresh hull ratio of almond fruit varies between 35% and 62%, almond hull was evaluated as silage, comparisons were made according to the almond variety (Prgomet et al. 2017). As over the literature results of the almond hull in its natural state. seen in the current and other studies, the ratio of the outer In the present study, the CP value of almond hull silage was −1 hull is at very signiﬁcant levels and the results of the study 92.5 g kg . CP values in studies for almond hull were 51.4– −1 −1 are similar to the literature studies. 48.7 g kg (DePeters et al. 2020), 81.1 g kg (Elahi et al. −1 −1 The chemical and nutritional content of fresh and silaged 2017), 45.0 g kg (Swanson et al. 2021), 64.0 g kg (Williams −1 almond hulls are shown in Table 2. When the results are exam- et al. 2018), 32.7–26.5–32.0–23.2 g kg (Jafari et al. 2011) and −1 ined, it is seen that almond hull silage preserves its nutritional 41.1 g kg (Calixto and Cañellas 1982). Although the CP value when compared to its fresh form. The dry matter content value of an almond hull is low, it has diﬀerent results. In the −1 −1 of both samples was 298.4 and 310.6 g kg of the almond hull current study, the CP (92.5 g kg ) value was higher than the −1 as fresh and silage, respectively. In the literature, the almond literature results. The mean values of CP were 59.5 g kg −1 hull was generally evaluated in its dry form and no data were (Dairy One 2022) and 57.0 g kg (Feedipedia 2022) in two found regarding the dry matter percent of the fresh material. diﬀerent feed libraries open to public access online. The CP After that, the current study will focus on the silage value of value of the almond hull in the present study is similar to the the almond hull. However, the nutritional values of almond CP value of corn silage. In addition, in a study conducted on hulls in the fresh form before silage are also expressed in horses fed with diﬀerent amounts of the almond hull, it was determined that as the almond hull ratio increased, the CP digestion rate decreased (Clutter and Rodiek 1992). Table 2. Chemical & nutritional composition of the almond hull as fresh and −1 The EE value of the silage, which was the subject of the silage, g kg (dry matter basis), unless otherwise stated. −1 study, was determined as 10.4 g kg and it was evaluated Indices Fresh almond hull Silage almond hull SEM P that the ether extract amount was low. In other studies, EE Dry matter 298.4 ± 2.7 310.6 ± 3.3 3.02 0.000 −1 −1 Crude protein 79.6 ± 2.9 92.5 ± 5.9 4.63 0.002 values were 29.6 g kg (Elahi et al. 2017), 37.0 g kg (Williams −1 Ether extract 9.1 ± 1.0 10.4 ± 0.5 0.77 0.025 et al. 2018) and 4.4–9.1–8.4 g kg (Jafari et al. 2011). It can be Crude ash 113.0 ± 1.5 111.3 ± 1.1 1.30 0.077 seen that the results of each study diﬀered from each other, Crude ﬁbre 175.7 ± 2.2 183.4 ± 2.9 6.10 0.081 ADF 267.6 ± 3.8 282.7 ± 2.9 3.40 0.000 and the results of the current study were compatible with the NDF 339.2 ± 3.9 394.3 ± 2.7 3.89 0.000 literature data. ADICP 27.3 ± 0.3 28.7 ± 0.8 0.59 0.005 The average crude ash value of the samples was 111.3 g NDICP 64.2 ± 0.3 74.4 ± 13.9 9.80 0.136 −1 −1 Lignin 111.4 ± 0.9 122.3 ± 4.3 3.13 0.001 kg . In other studies, ash values are 114.8 g kg (Elahi et al. −1 Starch 58.9 ± 0.8 61.6 ± 0.8 0.28 0.001 2017), 59.0 g kg (Swanson et al. 2021), 81.2–86.1–128.3– Total sugar 5.2 ± 0.2 10.1 ± 0.3 0.27 0.000 −1 −1 62.7 g kg (Jafari et al. 2011) and 60.9 g kg (Calixto and NFC 459.1 ± 7.8 391.5 ± 7.2 7.52 0.000 TDN 551.4 ± 3.7 521.7 ± 8.5 6.54 0.000 Cañellas 1982). One report stated that the almond hull 1X DDM 680.5 ± 3.0 668.8 ± 2.3 2.65 0.000 should not contain more than 9.0% ash at a moisture content DMI % 3.54 ± 0.04 3.04 ± 0.03 0.04 0.000 (body weight%) of 13.0% (CDFA 2013). When this criterion is evaluated based ME (Mcal/kg) 1.96 ± 0.01 1.85 ± 0.03 0.03 0.000 NE (Mcal/kg) 1.19 ± 0.01 1.11 ± 0.02 0.02 0.000 on the dry matter, it means that the raw ash value over −1 DM: dry matter, ADF: acid detergent ﬁbre, NDF: neutral detergent ﬁbre, ADICP: 103.5 g kg is not suitable in terms of quality criteria. In the acid detergent insoluble crude protein, NDICP: neutral detergent insoluble current study, the ash value was slightly above the criterion. crude protein, NFC: non-ﬁbre carbohydrate, TDN : total digestible nutrition, 1X Some of the study results meet this criterion and some do DDM: digestible dry matter, DMI: dry matter intake of body weight, ME: metab- olize energy, NE : net enegy lactation, SEM: Standard error means. not. The reason for the high ash value in some studies may L JOURNAL OF APPLIED ANIMAL RESEARCH 21 be the contamination of the soil during the harvesting and reason, both the lignin value and other nutritional values of the drying of almond fruits. However, in the current study, since outer hull may vary, and its quality changes. −1 the almonds were collected by hand, there was no contami- Starch content was determined as 61.6 g kg .Indiﬀerent −1 nation with soil, so the ash value can be considered as an indi- studies, starch contents were determined as 4.4–16.6 g kg −1 cator of high mineral content. (DePeters et al. 2020) and 9.3–26.0 g kg (Dairy One 2022; Fee- −1 The crude ﬁbre ratio in this paper was 183.4 g kg . In other dipedia 2022). In this study, the starch content was found to be −1 studies, the CF value were 129.6–150.7 g kg (DePeters et al. higher than in other studies. The total sugar content of almond −1 −1 −1 2020), 149.0 g kg (Swanson et al. 2021) and 106.0 g kg hull silage was 10.1 g kg . In a study on the almond hull, it was (Calixto and Cañellas 1982). The CF amount in the almond stated that the total sugar content ranged between 18% and −1 hull is not more than 150.0 g kg at 13% moisture, which is 30% (Prgomet et al. 2017), and in another study it ranged an important parameter in terms of quality (CDFA 2013). We between 30.6% and 42.0% (Oﬀeman et al. 2014). The total −1 can correct the value as 172.4 g kg on the basis of dry sugar amount in this study does not comply with the literature. matter. The average CF value was expressed as 191.6 and The reason is not fully understood. In this study, it was thought −1 153.0 g kg in two diﬀerent digital sources where the feed that a low fermentable carbohydrate ratio caused insuﬃcient analysis values are indicated (Dairy One 2022; Feedipedia fermentation quality. However in the literature, it is stated 2022). The CF value of the current study was determined as a that the total sugar content of the almond hull is high, so value close to the quality criteria determined by CDFA. The more studies should be done on this subject. diﬀerence between almond hull results may vary depending The values energy and digestibility were calculated as −1 −1 on the almond type, the amount of foreign matter mixed NFC – 391.5 g kg ; TDN – 521.7 g kg ; DDM – 668.8 g 1X −1 −1 with the almond hull and the adhesion of the inner shell to kg ; DMI – 3.04%; ME – 1.85 Mcal kg and NEL – BW% −1 the inner part of the outer hull in some species. 1.11 Mcal kg . In a similar study, two diﬀerent types of −1 ADF and NDF values for this study were 282.7 and 394.3 g almond hulls were expressed as 672.0–633.1 g kg for NFC, −1 −1 −1 kg , respectively. The study examining the eﬀect of the 694.6–670.0 g kg for TDN and 1.63–1.46 Mcal kg for NEL −1 almond hull used at diﬀerent rates in horse diets showed (DePeters et al. 2020). In other studies, NFC was 640.0 g kg , −1 that the rate of ADF digestion was not aﬀected (Clutter and NEL as 1.6 Mcal kg (Swanson et al. 2021), NFC as 330.0 g −1 −1 Rodiek 1992). In one study (DePeters et al. 2020), ADF and kg and TDN as 555.0 g kg (Alibés et al. 1983). In a table −1 NDF ratios were 133.8–192.6 g kg for one variety and with more almond hull analysis results, TDN and NEL are −1 −1 −1 158.9–220.7 g kg for another variety, respectively. In other 582.9 g kg and 1.33 Mcal kg , respectively (Dairy One −1 studies, ADF and NDF were 296.6–598.3 g kg (Elahi et al. 2022). The results are partially similar to the literature data. −1 2017), 149.0–238.0 g kg (Swanson et al. 2021) and 436.0– This is due to the nutrient content that varies due to diﬀerent −1 508.0 g kg (Williams et al. 2018). In a study in which the reasons. hulls of four diﬀerent almond varieties were evaluated, it was In the present study, the mineral contents of the almond stated that the ADF value ranged between 188.3 and 252.2 g hull as fresh and silage are given in Table 3. The order of −1 −1 kg , and the NDF value between 280.5 and 326.4 g kg mineral content (ppm) of almond hull silage was found as K (Jafari et al. 2011). It can be seen that the results diﬀer consider- >Ca>Mg >Na>Cu >S>Fe>Zn >Al>Mn >Si>Ni >P>Mo ably from each other. ADF and NDF values were low in some > Co > Se > Hg > Cr,As. The maximum amount of K was studies and high in some studies. The results of current and 1212.50 ppm, followed by Ca and Mg with 621.36 and other studies show that the quality of the almond hull as 586.25 ppm, respectively. In another study, the highest feed can be highly variable. The variability in these values mineral content of 2880 and 3450 ppm K was determined in also leads to the variability of the digestion rate. two diﬀerent types of almond hulls (DePeters et al. 2020). In ADICP and NDICP analysis results to determine the amount diﬀerent studies, the highest K was determined as 2500 ppm of nitrogen bound to cell wall components were 28.7 and (Swanson et al. 2021) and 3370 ppm (Alibés et al. 1983). In −1 74.4 g kg , respectively. No other study was found in which this study, as in other studies, signiﬁcant levels of K were these values were determined in the almond hull. However, detected in almond hulls. The high amount of K and its simi- in an open-access online feed library, the ADICP and NDICP larity to alfalfa may be a limiting factor in the transition −1 values for the almond hull are 18.5 and 23.0 g kg , respectively period nutrition of cows. When the K values in this study and (Dairy One 2022). In the present study, the results were higher the literature are examined, the possibility of the almond hull than these values. It is considered that this is a diﬀerence due to and silage increasing the cationicity of the diet should be con- the internal heating of the products, depending on the storage sidered and the possibility that it may increase the risk of post- conditions. partum milk fever should be evaluated. Ca and Mg values were −1 The lignin value was 122.3 g kg . The value of lignin in 621.36 and 586.25 ppm, respectively. In the literature, Ca −1 other studies: 76.3–86.9 g kg for two diﬀerent varieties (DeP- (190.00–240.00 ppm) and Mg (90.00–110 ppm) were deter- −1 eters et al. 2020), 72.0 g kg (Swanson et al. 2021) and 122.5– mined for two diﬀerent types of almond hulls (DePeters et al. −1 107.0 g kg in two diﬀerent feed libraries that provide online 2020), while in other studies Ca and Mg were 1080.00 and access (Dairy One 2022; Feedipedia 2022). The variability of 220 ppm (Alibés et al. 1983) and Ca as 370.00 ppm (Jafari lignin value can be evaluated as the adhesion of the inner et al. 2011), respectively. It has been observed that the heavy shell to the inner surface of the outer hull in some almond metal contents are below the risky levels. Although the species. In some cases, the inner shell, which has a woody struc- results in the literature and the results in the current study ture, cannot be completely cleaned from the outer hull. For this are diﬀerent, the proportional amounts of minerals in the 22 S. SIRAKAYA −1 Table 4. Microbiological values of almond hull silage, log cfu g . However, these results were compared with the values that Indices Results should be in legume silages with <30–35% dry matter (lactic Yeast Not detected acid: 60.0–80.0, acetic acid: 20.0–30.0, propionic acid: <5, −1 Mould Not detected butyric acid: <5 g kg ) (Kung et al. 2018). The amounts of Enterobacteria Not detected lactic and acetic acid were determined at the desired level, Lactic acid bacteria 4.54 ± 0.04 while the amounts of propionic and butyric acids were deter- mined in undesired amounts. According to the ﬂeig scoring, in which the silage quality is determined, the percentage distri- almond hull are similar and most K, Ca and Mg minerals are bution of lactic, acetic and butyric acid amounts in the total found in the hull. amount, almond hull silage is in the satisfactory silage quality Nutrient variations in almond hulls may due to the type of group (Canpolat 2019). The presence of high amounts (>5.0 g almond and the region where it grows, soil and climate, etc. −1 kg ) of propionic and butyric acids can often be an indication The degree of purity, cleanliness and mixing ratio of the inner of clostridial activity. Some clostridia bacteria have the ability shell to the outer hull of the hulls should also be considered to convert sugar to butyric acid, and some to convert lactic as another reason for the variation in results. acid to butyric acid. This causes the pH level to be higher than Almond hull silage microbiological analyses are given in expected (Kung et al. 2018). An increase in the amount of propio- Table 4. As a result, yeast–mould and enterobacteria were nic and butyric acids may have occurred with the use of the small not detected in the samples. The number of lactic acid bacteria −1 amount of sugar in the almond hull in the current study by clos- was 4.54 log cfu g . The absence of yeast–mould and entero- tridium. In the current study, acidity did not develop suﬃciently bacteria is a positive situation in terms of silage quality. Signiﬁ- and it does not bring the microbial ﬂora and the organic acid cant proliferation of lactic acid bacteria is considered to have a proﬁle to the desired level. positive eﬀect on the quality of almond hull silage but the Although it is not exactly similar to this study, in another study, silage acidity and organic acid results stated below do not it was mentioned that value-added products can be produced by support this situation suﬃciently. In terms of microbiology, the fermentation of almond hulls. In this context, 0.55–0.47–0.37 g there is no similar data or literature study related to the −1 g of lactic acid was produced from almond hulls with diﬀerent almond hull and its silage. sugar content in the range of 5.5 < pH < 6.0 (Thomas et al. 2019). The results of pH, NH –N, lactic acid, acetic acid, propionic The fermentation pH value in this study is consistent with the pH acid and butyric acid for evaluating the fermentation proﬁle value measured in the current study. are listed in Table 5. The average pH value of almond hull According to the results of a feed analysis table, which is silage samples was 5.75 ± 0.01 and no similar study data were expressed as ‘almond hull wet’ and shows that the DM ratio found in the literature. However, in the open-access feed varies between 76.03% and 87.27%, the amounts of aﬂatoxin library resource, the pH of the almond hull is 5.10. It was men- B1 and aﬂatoxin G1 are 0.587 and 0.237 ppm, respectively tioned that the target pH level should be 4.30–5.00 in legume (Dairy One 2022). These results show that there may be a risk silages and the buﬀering eﬀect of the high crude ash value of mycotoxins in almond hulls depending on storage con- (Kung et al. 2018). In the current study, the pH value could ditions and humidity. To prevent the mycotoxin formation in not be determined at the desired levels. It is considered that the fresh almond shell, making silage or adding it to silages this may be due to the buﬀering eﬀect of the high ash such as corn silage may be important. content of almond hull silage and the lower-than-expected −1 total sugar content. The NH –N value was 112.5 ± 1.45 g kg . No data were found related to this value studied in the Conclusion almond hull and its silage. In a review study, it was stated Many of the by-products that can not be consumed by humans that the NH –N value of legume silage should be between −1 are beneﬁcial for cows. In this sense, almond hulls are already 100.0 and 150.0 g kg (Kung et al. 2018). Since the NH –N consumed by cows. However, in this study, the feed value value was within the recommended range, it was evaluated was determined by making a silage of almond hull. In this that there was no signiﬁcant degradation in the protein struc- paper, almond hull silage was found to be of medium quality, ture of the almond hull in the silage process. In terms of organic −1 and this is considered to be due to the low fermentable carbo- acid proﬁle, the amount of lactic acid is 63.79 ± 1.83 g kg , −1 hydrate content of the almond hulls used in the study. acetic acid is 22.94 ± 1.93 g kg , propionic acid is 28.27 g −1 −1 However, there is information in the literature indicating that kg ± 1.01 and butyric acid is 9.59 ± 0.88 g kg . No data the fermentable carbohydrate content of the almond hull is could be found in the sources to compare organic acid results. higher. As a result, the almond hull can be stored as silage while it has the appropriate moisture content, in conditions where it is not possible to dry or when it is desired to be Table 5. Organic acid, pH and ammonia nitrogen values of almond hull silage, g −1 kg (dry matter basis). stored by leaving it to fermentation. It is recommended to Indices Results conduct more detailed (in vivo, in vitro) and diﬀerent studies pH 5.75 ± 0.01 to support the results of this study and other studies. NH –N 112.5 ± 1.45 Lactic acid 63.79 ± 1.83 Acetic acid 22.94 ± 1.93 Disclosure statement Propionic acid 28.27 ± 1.01 Butyric acid 9.59 ± 0.88 No potential conﬂict of interest was reported by the author(s). JOURNAL OF APPLIED ANIMAL RESEARCH 23 Fadel JG. 1999. Quantitative analyses of selected plant by-product feed- Data availability statement stuﬀs, a global perspective. Anim Feed Sci Technol. 79(4):255–268. The data that support this study will be shared upon reasonable request to Feedipedia. 2022. Almond hulls and almond by-products. Anim Feed the corresponding author. Resour Inf Syst. https://www.feedipedia.org/node/27. 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Journal of Applied Animal Research – Taylor & Francis

Published: Dec 31, 2023

Keywords: Almond hull; almond hull silage; silage fermentation

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Chemical, nutritive, fermentative and microbial composition of almond hull silage

Chemical, nutritive, fermentative and microbial composition of almond hull silage

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Chemical, nutritive, fermentative and microbial composition of almond hull silage

Chemical, nutritive, fermentative and microbial composition of almond hull silage

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