نوع مقاله : مقاله پژوهشی
نویسندگان
1 بخش تحقیقات علوم دامی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان چهارمحال و بختیاری، سازمان تحقیقات، آموزش و ترویج کشاورزی،شهرکرد،ایران.
2 بخش تحقیقات علوم دامی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان چهارمحال و بختیاری، سازمان تحقیقات، آموزش و ترویج کشاورزی، شهرکرد، ایران.
3 گروه علوم دامی دانشکده کشاورزی دانشگاه شیراز، شیراز. ایران.
4 گروه علوم دامی دانشکده کشاورزی دانشگاه ایلام. ایلام، ایران.
5 دانشکده دامپزشکی، دانشگاه آزاد اسلامی شهرکرد. شهرکرد. ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Introduction
The limitation of natural resources and rangelands clearly demonstrates the necessity of proper utilization of crop residues and by-products of food processing industries in ruminant nutrition, as these animals are capable of utilizing such products. Therefore, identifying their nutritional value is of economic importance. On the other hand, the consumption of these feed resources not only supplies part of the animals' nutrient requirements but also reduces the environmental problems associated with them. Feeding animals with argo-industerial residues reduce the competition between livestock and humans for food resources that are suitable for human consumption. Therefore, given the forage limitations in the country, optimal utilization of agricultural residue for livestock feed supply is essential. Barley brewing residue consists of insoluble materials that remain after the extraction of malt from barley grains. Due to its high moisture content (70 to 75 percent), it undergoes rapid fermentation and rancidity. This by-product contains approximately 20 to 25 percent crude protein (CP) and 50 to 54 percent neutral detergent fiber (NDF). Ensiling is a preserving and utilizing method for incorporating this product in ruminants’ diet (Wang et al., 2020). However, due to the low energy content of wet barley brewery (resulting from the conversion of starch to maltose and dextrin, and the removal of these compounds as malt extract), it is preferable to use carbohydrate sources during silage preparation. Therefore, the present experiment was aimed to study the quality characteristics and in vitro fermentation kinetics of barley brewing residue silage containing malt extract powder or barley powder after 15 and 30 days of silage making.
Method
Chemical composition including dry matter (DM), CP, ash, NDF, acid detergent fiber (ADF) and acid detergent lignin (ADL) of wet barley brewing residue were determined by standard methods before making silage. Wet barley brewing residues were ensiled in experimental scale (2 to 3 kg). Two silage additives were tested: malt extract powder and barley powder, each incorporated at 15 percent inclusion rate. This created two distinct treatment groups: silages containing 15 percent barley powder and silages containing 15 percent malt extract powder. Silos were opened and evaluated at two time points: 15 days and 30 days post-conservation, allowing assessment of temporal effects on silage quality parameters. Post-ensiling analyses included DM, CP, and ash, NDF, ADF and ADL were determined by standard methods. Quality characteristics assessment encompassed both organoleptic evaluation (color and odor) and quantitative measurements including pH, ammonia-nitrogen (NH₃-N) concentration, lactic acid concentration, acetic acid concentration, and calculation of the Fleig index. In vitro evaluation employed gas production techniques to assess fermentation kinetics. Parameters measured included gas production potential, gas production rate, and lag time. After 24 hours of in vitro incubation, ammonia-nitrogen concentrations and protozoal populations were determined. Additionally, metabolizable energy (ME), organic matter digestibility (OMD), and short-chain fatty acids (SCFA) were estimated using established predictive equations derived from gas production data. Treatment means were compared using Tukey's test for multiple comparisons. Statistical significance was declared at P ≤ 0.05, while P-values between 0.05 and 0.10 were interpreted as trends toward statistical significance.
Results
Analysis of dry matter content revealed that wet barley brewing silages containing malt extract powder and those containing barley powder did not differ significantly at either 15 or 30 days after opening. However, when comparing additive types, the addition of barley powder resulted in significantly higher dry matter content compared to equivalent amounts of malt extract powder (P < 0.05). This finding suggests that barley powder may contribute more effectively to moisture reduction or dry matter preservation during the ensiling process. Crude protein percentage, ash content, NDF, ADF, lignin concentration, ammonia-nitrogen concentration, and lactic acid concentration showed no significant differences between silage treatments (P > 0.05). This indicates that both carbohydrate sources provided comparable preservation of protein and fiber fractions during fermentation. Acetic acid concentration demonstrated a time-dependent response in wet barley brewing silages containing barley powder, with concentrations increasing significantly as silage storage time extended from 15 to 30 days (P < 0.05). This pattern suggests continued fermentation activity and potential shifts in microbial populations during extended storage. Both pH and Fleig index were significantly influenced by additive type and storage duration. For both malt extract powder and barley powder treatments, pH decreased and Fleig index increased over time (P < 0.05). The decreasing pH indicates progressive acidification during fermentation, which is desirable for silage preservation. The increasing Fleig index reflects improved overall silage quality with extended storage, as this index integrates multiple fermentation parameters into a single quality indicator. Gas production potential, gas production rate, metabolizable energy, organic matter digestibility, and estimated short-chain fatty acids showed no significant differences between silage treatments containing either additive type or at different opening times (P > 0.05). This suggests that both carbohydrate sources supported comparable ruminal fermentation characteristics and nutrient availability. However, lag phase duration demonstrated a significant treatment-by-time interaction. Specifically, in wet barley brewing silages containing malt extract powder, the lag phase increased with extended storage time (P < 0.05). This finding indicates that malt extract-containing silages may require longer adaptation periods for ruminal microorganisms after extended storage, potentially affecting initial fermentation rates in vivo. Total protozoal populations and specific genera including Entodinium, Epidinium, and Diplodinium showed significant increases with extended storage time in wet barley brewing silages containing barley powder (P < 0.05). This response suggests that barley powder supplementation may create more favorable conditions for protozoal survival and proliferation during ensiling, which could have implications for ruminal fiber digestion and overall feed utilization efficiency.
The results showed that the dry matter content of wet barley brewing residues silages containing malt extract powder and wet barley brewing residues silages containing barley powder did not differ significantly at 15 and 30 days after opening. However, addition of barley powder compared to the same amount of malt extract increased the dry matter content of the silage (P<0.05). Crude protein percentage, ash, NDF, ADF, lignin, ammonia nitrogen concentration, and lactic acid did not differ significantly between silages (P > 0.05). Acetic acid concentration in wet barley brewing silages containing barley powder increased with increasing silage storage time (P < 0.05). The pH and Flieg index of wet barley brewing silages were influenced by additive type and storage time; and for both additive types, pH decreased and Flieg index increased over the time (P < 0.05). Gas production potential, gas production rate, metabolizable energy, organic matter digestibility, and estimated short-chain fatty acids of wet barley brewing silages with both additive types and at different opening times did not differ significantly (P>0.05). However, with increasing storage time in wet barley brewing silages containing malt extract powder, the lag phase increased (P < 0.05). Total protozoa population and the genera Entodinium, Epidinium, and Diplodinium in wet barley brewing silages containing barley powder increased with increasing silage storage time (P < 0.05).
Conclusions
Results of this study indicated that wet barley brewing silage containing a carbohydrate source can be included in ruminant diets, and the addition of carbohydrate sources contributes to extending the storage time of wet barley brewing silage.
کلیدواژهها [English]
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