Bell D J, Spitzer J C, Burns G L
Animal and Veterinary Sciences Department, Clemson University, SC 29634, USA.
Theriogenology. 1998 Oct 1;50(5):707-15. doi: 10.1016/s0093-691x(98)00176-9.
We concurrently evaluated early weaning and once-daily suckling as options for shortening postpartum interval to estrus in primiparous cows calving in good body condition. Over 2 consecutive years, a total of 77 primiparous cows were assigned to 1 of 3 treatments: control (ad libitum suckling); once-daily suckling (for 30 d prior to start of breeding); or early weaning (calves weaned 30 d prior to start of breeding). All cows had a body condition score (BCS) of > or = 5 at parturition and were maintained in good condition throughout the breeding season. Cows were observed for estrus twice daily and blood samples for subsequent measurement of progesterone were collected at 48-h intervals. For data analysis, cows were divided into early- (> or = 85 d post partum) and late-calving (< 85 d post partum) groups at the onset of the breeding season. All calves were weighed at birth, at the onset of treatment, at weekly intervals until the start of the breeding season, and within 45 d of 205 d of age. Early weaning or once-daily suckling shortened the postpartum interval to first estrus of late-calving primiparous cows by 17 (P < 0.01) and 12 d (P < 0.08), respectively, compared with control group cows. However, among early-calving cows, neither early weaning nor once-daily suckling influenced the postpartum interval. Postpartum intervals of once-daily suckled cows and early-weaned cows were similar (P > 0.10).
我们同时评估了早期断奶和每日一次哺乳这两种方式，看其是否能缩短体况良好的初产母牛产后至发情的间隔时间。在连续两年的时间里，总共77头初产母牛被分配到以下三种处理方式中的一种：对照组（自由哺乳）；每日一次哺乳（在配种开始前30天）；或早期断奶（在配种开始前30天给犊牛断奶）。所有母牛在分娩时的体况评分（BCS）均≥5，并且在整个繁殖季节都保持良好的体况。每天观察母牛发情两次，并每隔48小时采集血样用于后续孕酮测定。为了进行数据分析，在繁殖季节开始时，将母牛分为早产犊牛组（产后≥85天）和晚产犊牛组（产后<85天）。所有犊牛在出生时、处理开始时、直到繁殖季节开始每周称重一次，以及在205日龄的45天内称重。与对照组母牛相比，早期断奶或每日一次哺乳分别使晚产犊牛组初产母牛产后至首次发情间隔时间缩短了17天（P<0.01）和12天（P<0.08）。然而，在早产犊牛组母牛中，早期断奶和每日一次哺乳均未影响产后间隔时间。每日一次哺乳的母牛和早期断奶的母牛产后间隔时间相似（P>0.10）。
