Facultad de Zootecnia y Ecología, Universidad Autónoma de Chihuahua, Chihuahua, Mexico 31453.
J Dairy Sci. 2010 Sep;93(9):4180-8. doi: 10.3168/jds.2009-2952.
Four dairy farms were used to determine the effects of water addition to diets and sample collection location on the particle size distribution and chemical composition of total mixed rations (TMR). Samples were collected weekly from the mixing wagon and from 3 locations in the feed bunk (top, middle, and bottom) for 5 mo (April, May, July, August, and October). Samples were partially dried to determine the effect of moisture on particle size distribution. Particle size distribution was measured using the Penn State Particle Size Separator. Crude protein, neutral detergent fiber, and acid detergent fiber contents were also analyzed. Particle fractions 19 to 8, 8 to 1.18, and <1.18 mm were judged adequate in all TMR for rumen function and milk yield; however, the percentage of material>19 mm was greater than recommended for TMR, according to the guidelines of Cooperative Extension of Pennsylvania State University. The particle size distribution in April differed from that in October, but intermediate months (May, July, and August) had similar particle size distributions. Samples from the bottom of the feed bunk had the highest percentage of particles retained on the 19-mm sieve. Samples from the top and middle of the feed bunk were similar to that from the mixing wagon. Higher percentages of particles were retained on >19, 19 to 8, and 8 to 1.18 mm sieves for wet than dried samples. The reverse was found for particles passing the 1.18-mm sieve. Mean particle size was higher for wet than dried samples. The crude protein, neutral detergent fiber, and acid detergent fiber contents of TMR varied with month of sampling (18-21, 40-57, and 21-34%, respectively) but were within recommended ranges for high-yielding dairy cows. Analyses of TMR particle size distributions are useful for proper feed bunk management and formulation of diets that maintain rumen function and maximize milk production and quality. Water addition may help reduce dust associated with feeding TMR.
本研究选择了 4 个奶牛场，旨在探讨水分添加和采样位置对全混合日粮（TMR）颗粒度分布和化学组成的影响。试验共进行了 5 个月（4 月、5 月、7 月、8 月和 10 月），每周从搅拌车和饲料槽的 3 个位置（顶部、中部和底部）采集样品。为了确定水分对颗粒度分布的影响，部分样品进行了干燥处理。使用宾夕法尼亚州立大学颗粒度分级机对颗粒度分布进行了测量。同时分析了粗蛋白、中性洗涤纤维和酸性洗涤纤维含量。结果表明，所有 TMR 的 19-8mm、8-1.18mm 和<1.18mm 颗粒度分数均满足反刍功能和产奶量的需求；然而，根据宾夕法尼亚州立大学合作推广指南，TMR 中>19mm 的物料百分比高于推荐值。4 月的颗粒度分布与 10 月不同，但 5 月、7 月和 8 月的中间月份具有相似的颗粒度分布。饲料槽底部的样品具有最高的 19mm 筛上保留率。饲料槽顶部和中部的样品与搅拌车的样品相似。与干燥样品相比，湿样品中>19mm、19-8mm 和 8-1.18mm 筛上保留的颗粒百分比更高。而通过 1.18mm 筛的颗粒则相反。与干燥样品相比，湿样品的平均颗粒度更高。TMR 的粗蛋白、中性洗涤纤维和酸性洗涤纤维含量随采样月份的不同而变化（分别为 18-21%、40-57%和 21-34%），但均处于高产奶牛的推荐范围内。TMR 颗粒度分布分析有助于正确管理饲料槽和制定日粮，以维持反刍功能，最大限度地提高产奶量和牛奶质量。添加水分可能有助于减少与 TMR 喂养相关的粉尘。
