Erb R E, Chew B P, Malven P V, D'Amico M F, Zamet C N, Colenbrander V F
J Anim Sci. 1980 Jul;51(1):143-52. doi: 10.2527/jas1980.511143x.
Independent effects of certain partum and peripartum traits on subsequent milk yields (Y) during days 1 to 27 (Y27), 28 to 60 (Y60) and 1 to 200 (Y200) of lactation were estimated from data on 167 Holstein cows and first-calf heifers. The variables were health status, calf sex and covariates (linear, quadratic and cubic) of calf birth weight (CBW), cow age (CA), month of calving code (season) and the peripartum blood plasma concentrations (means of three samples taken from 48 hr prepartum to within 2 hr postpartum) of prolactin (PRL), progesterone (P4), estrone (E1), estradiol-17 beta (E beta) and estradiol-17 alpha (E alpha). Except for Y200 values, the measures of milk yield were positively correlated (P < .01) with each other and with CA, CBW, plasma PRL and plasma E beta. Plasma PRL, E beta and E1 were positively correlated with each other and with CA (PRL and E beta) and CBW (E1 and E beta). Covariates prominently and independently related to increases in Y were CA, CBW and plasma PRL (P < .01). Predicted Y27, Y60 and Y200, calculated with equations of the cubic model, increased by 12.4, 6.5 and 3.7%, respectively, between CBW of 37 and 50 kg, and by 16.6, 15.9 and 14.8% between plasma PRL concentrations of 50 and 195 ng/ml. Season of calving, calf sex and health status were associated with changes in Y27 but not Y60 or Y200. Within the health status group, only infectious disorders (metritis or mastitis) decreased (P < .025) milk yield adjusted for CA and cow weight (adjusted Y60 and Y200). Among all other cows, including those with dystocia alone, adjusted yields were increased by heavier calves (P < .07, Y60), high plasma PRL (P < .025, Y60) and below average plasma E1 (P < .025, Y200). It may be practical to increase milk yield by providing supplemental light prepartum to increase plasma PRL and by selecting sires to maintain CBW above average.
根据167头荷斯坦奶牛和初产小母牛的数据，估算了某些分娩期和围产期特征对泌乳第1至27天（Y27）、第28至60天（Y60）和第1至200天（Y200）后续产奶量（Y）的独立影响。变量包括健康状况、犊牛性别以及犊牛出生体重（CBW）、奶牛年龄（CA）、产犊月份代码（季节）的协变量（线性、二次和三次），以及催乳素（PRL）、孕酮（P4）、雌酮（E1）、雌二醇 - 17β（Eβ）和雌二醇 - 17α（Eα）的围产期血浆浓度（从产前48小时至产后2小时内采集的三个样本的平均值）。除Y200值外，产奶量指标彼此之间以及与CA、CBW、血浆PRL和血浆Eβ均呈正相关（P <.01）。血浆PRL、Eβ和E1彼此之间以及与CA（PRL和Eβ）和CBW（E1和Eβ）呈正相关。与Y增加显著且独立相关的协变量是CA、CBW和血浆PRL（P <.01）。用三次模型方程计算的预测Y27、Y60和Y200，在CBW为37至50千克之间分别增加了12.4%、6.5%和3.7%，在血浆PRL浓度为50至195纳克/毫升之间分别增加了16.6%、15.9%和14.8%。产犊季节、犊牛性别和健康状况与Y27的变化有关，但与Y60或Y200无关。在健康状况组中，只有感染性疾病（子宫炎或乳腺炎）会降低经CA和奶牛体重调整后的产奶量（调整后的Y60和Y200）（P <.025）。在所有其他奶牛中，包括仅患有难产的奶牛，较重的犊牛（P <.07，Y60）、高血浆PRL（P <.025，Y60）和低于平均水平的血浆E1（P <.025，Y200）会使调整后的产奶量增加。产前提供补充光照以增加血浆PRL，并选择种公牛以保持CBW高于平均水平，可能有助于提高产奶量。
