摘要
The objective of this study was to determine whether addition of water to a high-moisture total mixed ration reduces feed sorting by dairy cattle. Twelve lactating Holstein cows, individually fed once per day, were tested on 2 diets in a crossover design with 21-d periods. Diets had the same dietary composition and differed only in dry matter content, which was reduced by the addition of water. Treatment diets were 1) dry (57.6% DM) and 2) wet (47.9% DM). Dry matter intake (DMI) and milk production were monitored for each animal for the last 7 d of both treatment periods. For the final 3 d of each period, milk samples were taken for composition analysis and fresh feed and orts were sampled for particle size analysis. The particle size separator had 3 screens (19, 8, and 1.18 mm) and a bottom pan, resulting in 4 fractions (long, medium, short, fine). Sorting was calculated as the actual intake of each particle size fraction expressed as a percentage of the predicted intake of that fraction. Contrary to the hypothesis, cows sorted the wet diet more extensively than the dry diet. Sorting of the dry diet was limited to a tendency to refuse short particles, whereas the wet diet was sorted against long particles and for short and fine particles. Water addition reduced DMI, neutral detergent fiber intake, and starch intake of cows on the wet diet. Increased sorting on the wet diet resulted in a tendency for decreased concentration of dietary neutral detergent fiber consumed and also resulted in increased starch concentration of the diet consumed. Milk production and components were unaffected by treatment. Our results suggest that water addition to high-moisture total mixed rations, containing primarily haylage and silage forage sources, may not be an effective method to reduce sorting. Furthermore, water addition may negatively affect DMI and encourage sorting, resulting in the consumption of a ration with different nutrient composition than intended.
摘要译文
这项研究的目的是确定向高水分总混合日粮中添加水是否会减少奶牛的饲料分选。 12头泌乳荷斯坦奶牛，每天分别喂食一次，在21天的交叉设计中在2种饮食中进行测试。日粮具有相同的日粮组成，仅在干物质含量上有差异，这由于加水而减少了。治疗饮食1）干燥（57.6％DM）和2）潮湿（47.9％DM）。在两个治疗期的最后7天监测每只动物的干物质摄入量（DMI）和产奶量。对于每个时期的最后3天，取牛奶样品进行组成分析，并取新鲜饲料和orts进行粒度分析。粒度分离器具有3个筛（19,8和1.18mm）和底部盘，产生4个部分（长，中，短，细）。分类计算为每个粒度分数的实际摄入量，表示为该分数的预测摄入量的百分比。与假设相反，奶牛比干饮食更加广泛地分选了潮湿的饮食。干饮食的分选限于倾向于拒绝短颗粒，而潮湿的饮食是按照长粒和短粒和细粒排序的。添加水减少了湿饲料中的DMI，中性洗涤纤维摄入量和母牛的淀粉摄入量。在潮湿饮食中增加分选导致消耗的膳食中性洗涤纤维浓度降低的倾向，并导致消耗的饮食中淀粉浓度增加。牛奶生产和成分不受治疗影响。我们的研究结果表明，水分添加到高水分的总混合日粮中，主要含有haylage和青贮饲料来源，可能不是减少排序的有效方法。此外，加水可能会对DMI产生负面影响并鼓励分类，导致消耗具有不同营养成分的日粮。
E.K.Miller-Cushon;T.J.DeVries;. Effect of dietary dry matter concentration on the sorting behavior of lactating dairy cows fed a total mixed ration[J]. Journal of Dairy Science, 2009,92(7): 3292-3298