Lopez-Villalobos N, Jayawardana J M D R, McNaughton L R, Hickson R E
School of Agriculture and Environment, Massey University, Palmerston North 4410, New Zealand.
Department of Animal Science, Faculty of Animal Science and Export Agriculture, Uva Wellassa University, Badulla 90000, Sri Lanka.
JDS Commun. 2023 Feb 9;4(4):329-333. doi: 10.3168/jdsc.2022-0293. eCollection 2023 Jul.
Twice-a-day (TAD) milking during the whole lactation is practiced in about 55% of New Zealand herds and once-a-day (OAD) milking during the whole lactation in about 10% of herds. The remainder of farmers use a mixture of TAD and OAD. Results from long-term comparisons show that over a full-lactation cows milked OAD, on average, had lower yields of milk (27%), fat (23%), and protein (24%) and higher percentages of fat and protein than cows milked TAD, but cows milked OAD for the entire lactation had better reproductive performance. Herds of cows milked OAD have higher mean 3-wk submission rate, 6-wk in-calf rate, and conception to the first service, and lower not-in-calf rate than the herds of cows milked TAD for the entire lactation. Farmers that have adopted OAD milking have culled cows that are unsuitable for OAD, and used sires selected on a OAD selection index to produce cow replacements that are more suitable for OAD milking. This OAD index includes the same traits that are included in the New Zealand national selection index with different relative economic weights on these traits plus including udder support, front teat placement, milking speed, and body capacity. A pasture-based milk production system based on OAD can be an alternative for many dairy farmers to maintain or increase farm profitability, with the additional benefits of better cow fertility and flexibility of using labor.
在新西兰，约55%的奶牛群在整个泌乳期采用一天两次（TAD）挤奶，约10%的奶牛群在整个泌乳期采用一天一次（OAD）挤奶。其余奶农则采用TAD和OAD相结合的方式。长期比较结果表明，在整个泌乳期采用OAD挤奶的奶牛，平均产奶量（低27%）、脂肪产量（低23%）和蛋白质产量（低24%）较低，但其脂肪和蛋白质百分比高于采用TAD挤奶的奶牛，但在整个泌乳期采用OAD挤奶的奶牛繁殖性能更好。与在整个泌乳期采用TAD挤奶的奶牛群相比，采用OAD挤奶的奶牛群平均3周受胎率、6周怀孕率和首次输精受胎率更高，未怀孕率更低。采用OAD挤奶的奶农淘汰了不适合OAD挤奶的奶牛，并使用根据OAD选择指数挑选的种公牛来繁育更适合OAD挤奶的后备奶牛。这个OAD指数包含了新西兰国家选择指数中的相同性状，但这些性状的相对经济权重不同，此外还包括乳房支撑、前乳头位置、挤奶速度和体容量。基于OAD的以牧场为基础的牛奶生产系统，对于许多奶农来说，可能是维持或提高农场盈利能力的一种选择，还具有提高奶牛繁殖力和劳动力使用灵活性等额外好处。
