Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A8.
Department of Agricultural, Food and Nutritional Science, University of Guelph, Guelph, ON, Canada N1G 2W1.
J Dairy Sci. 2019 Mar;102(3):2173-2187. doi: 10.3168/jds.2018-15138. Epub 2019 Feb 1.
The objective of this study was to determine if the quantity of concentrate provided in an automated milking system (AMS) affects dry matter intake (DMI), attendance to the AMS, milk and milk component yield, feeding behavior, cow activity, and ruminal fermentation of lactating dairy cows fed isocaloric diets. Eight ruminally cannulated primiparous Holstein cows were used in a replicated 4 × 4 Latin square design with 28-d periods. Cows were housed in a freestall facility with a guided-traffic (feed-first) flow barn design. Treatments included 0.5, 2.0, 3.5, or 5.0 kg/d of dry matter of pellet in the AMS with an equivalent reduction of the same pellet in the partial mixed ration (PMR). Days 21 to 24 of each treatment period were used for DMI, milking performance (visits, yield, and composition), behavior, and ruminal pH determination, and d 25 to 28 were used for ruminal short-chain fatty acid and ammonia concentrations as well as total-tract digestibility. As imposed, consumption of AMS pellet linearly increased, equating to 0.50, 2.00, 3.49, and 4.93 kg of dry matter/d for the 0.5, 2.0, 3.5, and 5.0 kg/d treatments, respectively. Correspondingly, the standard deviation in AMS pellet intake among days linearly increased from 0.06 to 0.85 kg of dry matter/d as the quantity of concentrate in the AMS increased from 0.5 to 5.0 kg. The PMR DMI decreased linearly with increasing AMS concentrate allocation, but total DMI (PMR + AMS) was not affected (25.3 kg/d). As the AMS concentrate allocation increased, the selection against particles retained on an 18-mm sieve linearly increased and selection against particles retained on the pan decreased. Milking frequency (3.22 milkings/d), milk yield (37.5 kg/d), milk fat yield (1.43 kg/d), and milk protein yield (1.22 kg/d) were not affected; however, milk urea nitrogen concentration decreased linearly with increasing AMS concentrate. Ruminal pH averaged 6.18 and was not affected by AMS concentrate. Total ruminal short-chain fatty acid concentration was greatest when 3.5 kg of concentrate was allocated in the AMS and ruminal ammonia decreased linearly with increasing AMS concentrate. Time spent lying, the number of lying bouts, and average bout duration were not affected by treatment. These data indicate that increasing the quantity of concentrate in the AMS increases daily variability in AMS concentrate intake while decreasing PMR intake without affecting voluntary visits to the AMS and milk or milk component yield. As such, under isocaloric dietary settings, increasing the supply of pellet in the AMS is not likely to affect voluntary visits to the AMS, milk and milk component yields, or ruminal fermentation.
本研究旨在确定自动化挤奶系统（AMS）中提供的浓缩物数量是否会影响干物质摄入量（DMI）、对 AMS 的出勤率、牛奶和牛奶成分产量、采食行为、奶牛活动和泌乳奶牛的瘤胃发酵，同时这些奶牛饲喂等热量日粮。8 头荷斯坦奶牛在重复的 4×4 拉丁方设计中进行了 28 天的试验。奶牛被安置在一个带有导向交通（先喂料）的畜栏设计的自由式畜舍中。处理包括 AMS 中 0.5、2.0、3.5 或 5.0 kg/d 的干物质的颗粒，同时等量减少部分混合日粮（PMR）中的颗粒。每个处理期的第 21 至 24 天用于 DMI、挤奶性能（访问次数、产量和组成）、行为和瘤胃 pH 值测定，第 25 至 28 天用于瘤胃短链脂肪酸和氨浓度以及全肠道消化率。如所规定的那样，AMS 颗粒的消耗量呈线性增加，分别相当于 0.5、2.0、3.49 和 4.93 kg/d，对应于 0.5、2.0、3.5 和 5.0 kg/d 处理的干物质/d。相应地，随着 AMS 中浓缩物含量从 0.5 增加到 5.0 kg，AMS 颗粒摄入量的日标准差从 0.06 增加到 0.85 kg/d 呈线性增加。随着 AMS 中浓缩物分配的增加，对 18mm 筛上保留的颗粒的选择性呈线性增加，而对平底锅上保留的颗粒的选择性呈线性下降。PMR 的 DMI 呈线性下降，随着 AMS 中浓缩物分配的增加，但总 DMI（PMR+AMS）不受影响（25.3 kg/d）。随着 AMS 中浓缩物分配的增加，AMS 中浓缩物的日变异增加，而 PMR 的摄入量减少，而不会影响奶牛的自愿访问 AMS 和牛奶或牛奶成分的产量。然而，牛奶尿素氮浓度呈线性下降。瘤胃 pH 值平均为 6.18，不受 AMS 浓缩物的影响。当在 AMS 中分配 3.5 kg 浓缩物时，总瘤胃短链脂肪酸浓度最大，而瘤胃氨浓度随着 AMS 浓缩物的增加呈线性下降。处理对躺卧时间、躺卧次数和平均躺卧持续时间没有影响。这些数据表明，增加 AMS 中浓缩物的数量会增加 AMS 浓缩物摄入量的日变异性，同时减少 PMR 摄入量，而不会影响自愿访问 AMS 和牛奶或牛奶成分的产量。因此，在等热量饮食环境下，增加 AMS 中颗粒的供应量不太可能影响自愿访问 AMS、牛奶和牛奶成分的产量或瘤胃发酵。
