Kessler E C, Bruckmaier R M, Gross J J
Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstr. 109a, CH-3001 Bern, Switzerland.
Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstr. 109a, CH-3001 Bern, Switzerland.
J Dairy Sci. 2014;97(4):2186-92. doi: 10.3168/jds.2013-7573. Epub 2014 Jan 31.
In dairy cows, milk yield increases rapidly after parturition until a peak at around wk 6 of lactation. However, the description of the shape of the lactation curve is commonly based on weekly average milk yields. For a more detailed analysis of the milk production curve from the very beginning of lactation including the colostral period and the effect of colostrum yield on further lactational performance, the first 10 milkings after parturition, daily milk yields from d 1 to 28 of lactation, and the cumulative milk production on d 100 to 305 of lactation were investigated in 17 primiparous and 39 multiparous cows milked twice daily. Milk yield at the first milking after parturition (colostrum) ranged from 1.3 to 20.7kg (Δ=19.4kg) in multiparous and from 1.8 to 10.9kg in primiparous animals (Δ=9.1kg). At the tenth milking, milk production ranged from 9.2 to 21.5kg (Δ=12.3kg) in multiparous and from 7.0 to 15.2kg (Δ=8.2kg) in primiparous animals. Immediately after parturition, daily milk production increased rapidly, but after approximately 1wk in lactation, the slope of the daily milk production curve flattened and continued more linear. A nonlinear regression equation was used to determine this timely change, which occurred earlier in primiparous (d 6.9±0.3) than in multiparous cows (d 8.2±0.2). The correlation between the amount of first colostrum and milk production during further lactation decreased already from 0.47 on d 5 to 0.32 on d 14. In multiparous cows, the correlation between total milk production of the previous 305d standard lactation and the amount of first colostrum was not significant (correlation=0.29), whereas the correlation with the daily production increased from 0.45 on d 5 to 0.69 on d 14. However, in primiparous animals, correlations between first-colostrum yield and daily milk yields up to d 28 of lactation were not significant, possibly due to the smaller sample size compared with multiparous animals. First-colostrum yield and cumulative milk production of 100, 200, and 305 lactation days were not significantly correlated in multiparous and primiparous cows. In conclusion, the milk production during the first few milkings is widely independent from the overall production level of a cow. Potentially, genetic selection toward lower milk yield during the very first days after parturition at a simultaneously high lactational performance may be a tool to ensure sufficient colostrum quality and to reduce the metabolic load around parturition.
在奶牛中，产犊后产奶量迅速增加，直至泌乳第6周左右达到峰值。然而，泌乳曲线形状的描述通常基于每周平均产奶量。为了从泌乳开始（包括初乳期）更详细地分析产奶曲线以及初乳产量对后续泌乳性能的影响，对17头初产奶牛和39头经产奶牛进行了研究，这些奶牛每天挤奶两次，记录了产犊后前10次挤奶量、泌乳第1至28天的日产奶量以及泌乳第100至305天的累计产奶量。经产奶牛产犊后第一次挤奶（初乳）的产奶量在1.3至20.7千克之间（差值 = 19.4千克），初产奶牛在1.8至10.9千克之间（差值 = 9.1千克）。在第10次挤奶时，经产奶牛的产奶量在9.2至21.5千克之间（差值 = 12.3千克），初产奶牛在7.0至15.2千克之间（差值 = 8.2千克）。产犊后，日产奶量迅速增加，但在泌乳约1周后，日产奶量曲线的斜率变平缓，并继续呈更线性的变化。使用非线性回归方程来确定这一适时变化，该变化在初产奶牛中出现得更早（第6.9±0.3天），而在经产奶牛中为第8.2±0.2天。初乳量与后续泌乳期产奶量之间的相关性从第5天的0.47降至第14天的0.32。在经产奶牛中，前305天标准泌乳期的总产奶量与初乳量之间的相关性不显著（相关性 = 0.29），而与日产奶量的相关性从第5天的0.45增至第14天的0.69。然而，在初产奶牛中，直至泌乳第28天的初乳产量与日产奶量之间的相关性不显著，这可能是由于与经产奶牛相比样本量较小。经产奶牛和初产奶牛的初乳产量与泌乳第100、200和305天的累计产奶量均无显著相关性。总之，最初几次挤奶时的产奶量在很大程度上独立于奶牛的总体生产水平。潜在地，在产犊后最初几天朝着较低产奶量同时保持高产乳性能进行基因选择，可能是确保足够初乳质量并减轻产犊前后代谢负担的一种手段。
