SUBSTITUTION OF STARCH SOURCES BY SOLUBLE NEUTRAL DETERGENT FIBER IN DAIRY COWS DIET

Abstract The objective of this research was to evaluate the effects of replacing corn grain by citrus pulp on dairy cows performance. Nine Holstein cows (three cannulated in the rumen), at 80 ± 24 milking days, and daily medium production of 20 ± 0.58 kg/day were used. Animals were maintained in tie stall with individual feeder and drinker. Experimental design was a 3 x 3 Latin square. Experiment lasted 21 days, being 14 days of adaptation and seven of collection. Treatments were 100% corn grain (CG); 50% corn grain and 50% citric pulp (CG-P) or 100% citrus pulp (P). There were no differences in nutrients (DM, OM, NDF, ADF, CP, starch) ingestion among diets. The treatment with citrus pulp produced larger proportion of acetate in relation to the others, as well as larger acetate/propionate ratio. The pH averages ranged between 5.86 and 7.35. The averages of N-NH3 presented larger differences in the times 2 and 3 hours after feeding. There were no differences among the diets for total 4%-fat corrected milk production, protein, lactose, total dry extract (TDE) and milk urea nitrogen (MUN).摘要 本研究旨在评估以柑橘浆替代玉米谷物对荷斯坦奶牛生产性能的影响。试验选取9头泌乳天数为80±24天、日均产奶量为20±0.58 kg的荷斯坦奶牛，其中3头实施瘤胃插管；试验采用拴系饲养模式，每头奶牛配备独立饲槽与饮水装置。试验设计为3×3拉丁方试验设计，总时长21天，其中14天为适应期，7天为样品收集期。试验设置3个处理组：100%玉米谷物组（CG，corn grain）、50%玉米谷物与50%柑橘浆组（CG-P，corn grain and citrus pulp）以及100%柑橘浆组（P，citrus pulp）。各试验日粮的营养物质摄入量，包括干物质（Dry Matter, DM）、有机物（Organic Matter, OM）、中性洗涤纤维（Neutral Detergent Fiber, NDF）、酸性洗涤纤维（Acid Detergent Fiber, ADF）、粗蛋白（Crude Protein, CP）与淀粉，组间无显著差异。与其余两组相比，饲喂柑橘浆的处理组瘤胃液乙酸占比更高，且乙酸与丙酸的比值更大；瘤胃液pH平均值介于5.86至7.35之间。氨态氮（N-NH3）浓度在饲喂后2小时与3小时时差异最为显著。各试验日粮对4%乳脂校正乳产量、乳蛋白、乳糖、总干提取物（TDE，total dry extract）以及乳尿素氮（MUN，milk urea nitrogen）均无显著影响。