Department of Dairy Science, Virginia Tech, Blacksburg 24061.
Department of Dairy Science, Virginia Tech, Blacksburg 24061.
J Dairy Sci. 2021 Aug;104(8):9355-9361. doi: 10.3168/jds.2020-20100. Epub 2021 Apr 30.
Increasing milking frequency (MF) increases milk yield (MY) and farm profit, and optimal milking intervals (MI) prevent milk production decline. The objective of this experiment was to compare the MY effect of even and uneven 4 times daily (4×) MI in early lactation under increased MF. Fourteen multiparous and 6 primiparous cows were milked using unilateral frequent milking, with right udder halves milked 4× and left udder halves milked 2 times daily (2×) for 20 d in early lactation starting on d 5 postpartum. Ten (7 multiparous and 3 primiparous) cows were allocated evenly based on parity and assigned to either the even or the uneven MI groups distinguished by intervals of 9:3:9:3 h or 6:6:6:6 h. The left and right udder halves were milked at 0100 and 1300 h. The right udder glands were additionally milked at 0400 and 1600 h for the uneven MI group and at 0700 and 1900 h for the even MI group. Milk from each udder half was weighed and sampled for components on the final day of treatment and at 60, 120, 180, 240, and 300 d in milk. The overall effect of 4× milking on the right udder halves was a 5.96 ± 0.70 kg/d increase in MY on d 21 of unilateral frequent milking compared with the 2× udder halves. This elevated MY continued through 300 d in milk and averaged 1.56 ± 0.70 kg/d. Increased MF in early lactation increased the udder half difference in total yield throughout a 300-d lactation by 508 kg for milk, 25 kg for milk fat, and 15 kg for milk protein. Increased MF in early lactation increased milk component yields, but there were no differences between MI groups. The lack of treatment difference may be beneficial to farmers. The ability to achieve the same increased MY effect with uneven MI may optimize labor efficiency because early-lactation cows could be milked at the beginning and end of milking sessions. Farmers would not have to add additional milking sessions to achieve the enhanced MY response regardless of normal milking session length.
增加挤奶频率（MF）可以提高产奶量（MY）和农场利润，而最佳挤奶间隔（MI）可以防止产奶量下降。本实验的目的是比较在增加 MF 下，早期泌乳期均匀和不均匀的 4 次/d（4×）MI 对产奶量的影响。14 头经产和 6 头初产奶牛在产后第 5 天开始的早期泌乳期，采用单侧频繁挤奶，右乳区 4×挤奶，左乳区 2×挤奶，共 20d。10 头（7 头经产和 3 头初产）奶牛根据胎次均匀分配，并根据 9:3:9:3 h 或 6:6:6:6 h 的间隔分为均匀或不均匀 MI 组。左、右乳区分别于 0100 和 1300 h 挤奶。不均匀 MI 组的右乳区腺在 0400 和 1600 h 以及均匀 MI 组的右乳区腺在 0700 和 1900 h 分别额外挤奶。处理的最后一天以及处理后第 60、120、180、240 和 300d，从每个乳区分别称重和取样进行成分分析。与 2×乳区相比，单侧频繁挤奶第 21d，右乳区 4×挤奶的产奶量总体增加了 5.96±0.70kg/d。这种升高的产奶量在整个泌乳期 300d 内持续，并平均每天增加 1.56±0.70kg/d。早期泌乳期增加挤奶频率增加了整个泌乳期 300d 内左右乳区总产量的差异，牛奶增加 508kg、乳脂增加 25kg、乳蛋白增加 15kg。早期泌乳期增加挤奶频率增加了牛奶成分的产量，但 MI 组之间没有差异。这种处理差异可能对农民有益。采用不均匀的 MI 可以达到相同的增加产奶量效果，这可能优化了劳动力效率，因为在挤奶过程开始和结束时都可以对早期泌乳期奶牛进行挤奶。无论正常挤奶时间长度如何，农民都不必增加额外的挤奶时间来获得增强的产奶量反应。
