The effects of a limited grazing period on the performance, behaviour and milk composition of high‐yielding dairy cows were examined. A total of 56 Holstein cows yielding 44.7 ± 0.42 kg/day were allocated to one of four treatments in one of two, 4‐week periods. Treatments were as follows: control (C)—cows housed and offered TMR ad libitum; early grazing (EG)—cows grazed for 6 hr after morning milking then housed; delayed grazing (DG)—cows returned to housing for 1 hr after morning milking followed by grazing for 6 hr, then housed; restricted TMR (RT)—cows grazed for 6 hr after morning milking, then housed and fed TMR at 75% of ad libitum. Intake of TMR was highest in cows receiving C, intermediate in EG and DG, and lowest in RT at 26.9, 23.6, 24.7 and 20.3 kg DM/day respectively. Pasture intake was similar in cows receiving EG or DG, but was higher in RT at 2.4, 2.0 and 3.5 kg DM/day respectively. Milk yield was similar between cows receiving C, EG or DG, but lowest in RT at 45.7, 44.2, 44.9 and 41.7 kg/cow, respectively, while milk fat content of C18:3 n‐3 was increased by grazing. Cows in C spent more than 55 min/day longer lying and had three additional lying bouts/day, while lying bouts were shorter than for cows receiving EG, RT or DG. It is concluded that high‐yielding cows can be grazed for 6 hr/day with little impact on performance, provided TMR is available ad libitum when housed.

中文翻译：

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在有限放牧时期内高产荷斯坦奶牛的生产性能，牛奶脂肪酸组成和行为

研究了有限放牧期对高产奶牛生产性能，行为和乳成分的影响。将总共​​56头荷斯坦奶牛，每天生产44.7±0.42千克，分配给两个，四个星期之一的四个处理之一。处理方法如下：对照（C）-随意饲养和提供TMR的母牛；早期放牧（EG）-母牛在早晨挤奶后放牧6小时，然后放养；延迟放牧（DG）-牛在早上挤奶后回到家中1小时，然后放牧6小时，然后圈养；限制TMR（RT）-牛在早晨挤奶后放牧6个小时，然后以任意量的75％饲养和喂养TMR。在接受C的奶牛中，TMR的摄入量最高，在EG和DG中为中等，在RT的最低，分别为26.9、23.6、24.7和20.3 kg DM /天。接受EG或DG的奶牛的牧草摄入量相似，但RT分别较高，分别为2.4、2.0和3.5 kg DM /天。接受C，EG或DG的奶牛的产奶量相似，但RT最低，分别为45.7、44.2、44.9和41.7 kg /牛，而放牧提高了C18：3 n-3的乳脂含量。C区的母牛每天躺卧时间超过55分钟，每天有3次额外的躺卧运动，而躺卧运动的时间短于接受EG，RT或DG的母牛。结论是，只要饲养时可随意获得TMR，高产母牛可以每天放牧6个小时，而对生产性能的影响很小。C区的母牛每天躺卧时间超过55分钟，每天有3次额外的躺卧运动，而躺卧运动的时间短于接受EG，RT或DG的母牛。结论是，只要饲养时可随意获得TMR，高产奶牛每天可放牧6个小时，对生产性能影响很小。C区的母牛每天躺卧时间超过55分钟，每天有3次额外的躺卧运动，而躺卧运动的时间短于接受EG，RT或DG的母牛。结论是，只要饲养时可随意获得TMR，高产母牛可以每天放牧6个小时，而对生产性能的影响很小。