Department of Animal Science, Agricultural College, Shahrekord University, Sharekord, Iran.
Department of Animal Science, Agricultural College, Shahrekord University, Sharekord, Iran.
Theriogenology. 2023 Jul 15;205:9-17. doi: 10.1016/j.theriogenology.2023.04.014. Epub 2023 Apr 17.
The purpose of the current study was to investigate the effect of gestation length (GL) on productive performance, and the incidence of calving and reproductive diseases in Holstein dairy cows. In total, 3800 Holstein singleton cows (2000 heifers and 1800 cows) from two commercial dairy farms were used. The average gestation length for 3800 cows was 276 ± 6 d. Cows with GL shorter or longer than 3 SD from the mean were removed and considered outliers. This process led to the elimination of 20 cows from the 3800 cows enrolled in the study. Therefore, 3780 cows (1994 heifers and 1786 cows) remained for data analysis, with a range of GL between 258 and 294 d. The mean of GL for the remaining 3780 cows in the study was 276 ± 5 d, which were classified as short (SGL; more than 1SD less than the population mean, mean = 267, range 258-270 d), average (AGL; population mean ± 1SD, mean = 276, range 271-281 d), and long (LGL; more than 1SD greater than the population mean, mean = 284, range 282-294 d) gestation length. In primiparous cows, the incidence of stillbirth, retained placenta, metritis, and clinical endometritis were higher in the SGL cows than in the AGL cows, but the incidence of dystocia was similar across groups. In multiparous cows, the incidence of dystocia, retained placenta, and metritis were higher in the SGL cows than in the AGL cows, and the incidence of stillbirth was higher in the SGL and LGL cows than in the AGL cows. In primiparous cows, milk yield was not different across groups. However, in multiparous cows, the SGL cows had lower milk yield than the AGL cows. In primiparous cows, the SGL cows had lower colostrum production than the AGL cows, but in multiparous cows, there was no difference in colostrum production across groups. In general, cows with either short or long gestation length had impaired health and production, but this impact was more pronounced in cows with short gestation length.
本研究旨在探讨妊娠期（GL）对荷斯坦奶牛生产性能、分娩和生殖疾病发病率的影响。共使用了来自两个商业奶牛场的 3800 头荷斯坦单胎牛（2000 头小母牛和 1800 头母牛）。3800 头牛的平均妊娠期为 276±6d。将 GL 短于或长于平均值 3 个标准差的牛去除并视为异常值。这一过程导致从 3800 头入组牛中剔除了 20 头牛。因此，有 3780 头牛（1994 头小母牛和 1786 头母牛）可用于数据分析，GL 范围为 258 至 294d。研究中剩余 3780 头牛的 GL 平均值为 276±5d，分为短（SGL；短于群体平均值 1 个标准差以上，平均值=267，范围 258-270d）、平均（AGL；群体平均值±1 个标准差，平均值=276，范围 271-281d）和长（LGL；长于群体平均值 1 个标准差以上，平均值=284，范围 282-294d）妊娠期。在初产牛中，SGL 牛的死胎、胎衣不下、子宫内膜炎和临床子宫内膜炎的发病率高于 AGL 牛，但各组的难产发病率相似。在经产牛中，SGL 牛的难产、胎衣不下和子宫内膜炎的发病率高于 AGL 牛，SGL 和 LGL 牛的死胎发病率高于 AGL 牛。在初产牛中，各组间产奶量无差异。然而，在经产牛中，SGL 牛的产奶量低于 AGL 牛。在初产牛中，SGL 牛的初乳产量低于 AGL 牛，但在经产牛中，各组间初乳产量无差异。总的来说，妊娠期过短或过长的奶牛健康和生产状况都较差，但妊娠期过短的奶牛影响更为明显。
