نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشگاه شیراز
2 گروه علوم دامی، دانشکده کشاورزی، دانشگاه جیرفت، جیرفت، ایران
3 گروه تولیدات گیاهی، دانشکده کشاورزی، مجتمع آموزش عالی شیروان، شیروان، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objectives: Onion (Allium cepa) cultivation generates substantial by-products, with aerial parts (leaves and stems) often discarded after bulb harvesting. In Iran, annual onion production exceeds 3.15 million tons, yielding a lot of onion tops as agricultural waste. These residues, typically left in fields or occasionally grazed by sheep, possess untapped potential as livestock feed. However, their high moisture content and low water-soluble carbohydrate (WSC) levels present challenges for direct ensiling. This study evaluated the effects of urea, molasses, and waste date as silage additives on the nutritional quality, fermentation profile, and in vitro gas production of onion top silage.
Materials and Methods: Onion tops were collected from Jiroft farms, wilted for 24 hours to achieve about 30% dry matter (DM), and chopped into 1–2 cm pieces. The experimental treatments included: control (no additive), urea (2.5% and 5%), molasses (10% and 15%), and waste date (10% and 15%) on fresh weight basis. The prepared material was tightly packed into polyethylene bags, vacuum-sealed, and ensiled for 60 days. Post-ensiling analyses included chemical composition (DM, organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), WSC, and ammonia nitrogen (NH₃-N)), pH, and aerobic stability. In vitro gas production method was assessed, with derived parameters including metabolizable energy (ME), net energy for lactation (NEl), organic matter digestibility (OMD), and short-chain fatty acids (SCFA).
Results: Results indicated that all additives increased DM content compared to control (P< 0.05). Molasses and urea enhanced OM, while waste date reduced it. Urea supplementation significantly raised CP levels, whereas molasses and waste date had no significant effect. NDF and ADF decreased notably with molasses (P< 0.05), while urea and waste date only reduced NDF. WSC content increased substantially with molasses and waste date, but remained unaffected by urea. Fermentation quality varied significantly among treatments: pH was lowest in molasses-treated silage (3.87 at 15%) and highest with urea (8.12 at 5%). NH₃-N concentrations increased markedly with urea but decreased with molasses and waste date. Aerobic stability improved with molasses (48 h vs. 44 h in control). In vitro gas production analysis revealed that molasses (15%) enhanced cumulative gas production and OMD, while urea reduced the gas production rate. ME and NEl values were highest with molasses (8.88 MJ/kg DM and 5.13 MJ/kg DM, respectively).
Conclusion: In conclusion, molasses and waste date effectively improved the fermentation quality and nutritional value of onion top silage. Molasses demonstrated superior effects by increasing WSC, reducing pH, and enhancing aerobic stability, while waste date improved digestibility without compromising fermentation. Although urea increased CP content, its adverse effects on pH and NH₃-N limited its overall benefits. For optimal silage production from onion tops, the addition of molasses or waste date is recommended. These findings highlight the potential for sustainable utilization of agricultural by-products in ruminant diets, offering economic and environmental advantages through reduced feed costs and waste minimization.
کلیدواژهها [English]
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