我国北方地区娟姗牛泌乳曲线分析及其与荷斯坦牛的比较

为分析娟姗牛泌乳曲线的特征及其305 d产奶量的影响因素，并重点比较娟姗牛和荷斯坦牛两品种泌乳曲线间的差异，本研究收集了河北地区某规模化牧场2017年1月—2021年1月共1 721头娟姗牛和6 093头荷斯坦牛的日产奶量连续监测记录，利用Wood模型对奶牛的个体泌乳曲线进行拟合，并根据曲线特征确定了高峰奶、高峰日、日产奶量变化速率、各泌乳阶段产奶总量等指标对泌乳曲线进行剖析。利用SAS 9.4软件的GLM过程分析了胎次、产犊季节等因素对娟姗牛305 d产奶量的影响及两群体泌乳曲线间的差异。结果表明:1)Wood模型对娟姗牛泌乳曲线的拟合效果较好，泌乳曲线拟合度(R²)可达0.86；2)娟姗牛305 d产奶量受胎次、产犊季节等因素影响显著(P<0.05)，较高胎次及春季产犊的娟姗牛305 d产奶量更高；3)娟姗牛和荷斯坦牛的泌乳曲线在高峰奶、高峰日及日产奶量变化速率等方面均表现出显著差异(P<0.05)，娟姗牛的高峰日较荷斯坦牛提前了39.84天，而高峰奶占总产奶量的比例较荷斯坦牛高0.036%，且娟姗牛的泌乳主要集中于泌乳前期(1~99 d)，在泌乳后期(200~305 d)产奶量显著降低(P<0.05)。综上，本研究利用连续测定的日产奶量记录全面揭示了娟姗牛的泌乳特征，同时通过与荷斯坦牛泌乳曲线的比较为研究娟姗牛与荷斯坦牛的种间差异提供了有用信息，为今后利用连续监测的日产奶量记录进行奶牛产奶性能的遗传选育和牛群的精准管理提供了参考。

Analysis of lactation curve in Jersey cattle in northern China and its comparison with Holstein cattle

The objective of this study was to analyze the characteristics of the lactation curves and the influencing factors of 305 d milk yield in Jersey cattle, and compare the differences of the lactation curves between Jersey and Holstein. The continuous records of daily milk yield from 1 721 Jersey cattle and 6 093 Holstein cattle were collected in a large-scale daily farm in Hebei from January 2017 to January 2021. Wood model was used to fit the individual lactation curves, and peak yield, peak day, rate of change in daily milk yield and milk yield in different lactation stage were determined to analyze the characteristics of the lactation curve. The GLM procedure in SAS 9. 4 was used to analyze the impacts of parity and calving season on 305 d milk yield and the differences of the lactation curves between two breeds. The results showed: 1)The Wood model had a good fitting effect on the lactation curve of Jersey cattle, and its R² reached 0. 86; 2)The 305 d milk yield of Jersey cattle was significantly(P<0. 05)influenced by the parity and calving season; the 305 d milk yield of Jersey cattle with higher parity and calving in spring was higher; 3)The lactation curve of Jersey cattle and Holstein cattle was significantly(P<0. 05)different in terms of peak yield, peak day and rate of change in daily milk yield. The peak day of Jersey cattle was 39. 84 d earlier than that of Holstein cattle, and the proportion of peak yield in total milk yield was 0. 036% higher than that of Holstein cattle. The milk production of Jersey cattle was mainly concentrated in the early lactation(1-99 days)and the milk production decreased significantly in the late lactation(200-305 days)(P<0. 05). In conclusion, this study comprehensively revealed the lactation characteristics of Jersey cattle using continuous records of daily milk yield, provided information for exploring breed differences between Jersey and Holstein cattle and provided a reference for genetic selection and precise management of dairy farm using continuous records of daily milk yield.