中甸犏牛的产犊季节、泌乳期分布及产奶量变化规律

Study on Calving Season,Lactation Length Distribution and Patterns of Milk Yield of Zhongdian Cattle-yak

【目的】旨在探讨中甸犏牛的产犊季节、泌乳期分布及产奶量变化规律,为提升犏牛产奶量措施的制定等提供重要参考。【方法】基于香格里拉社区的犏牛养殖模式,对中甸犏牛(n=142)从产犊的第2天开始,每天早晚各挤奶一次,连续记录挤奶量直至停止挤奶为止,并统计分析产犊时间、泌乳期及各泌乳月的产奶量等。【结果】母犏牛在春、夏、秋和冬季产犊的比例分别占63.38%、30.99%、4.23%和1.41%。母犏牛的泌乳期分布范围宽,5个月(153 d)至14个月(427 d)不等,其中泌乳期为5个月的占24.40%,6~8个月的占46.40%,9~12个月的占28.0%,13~14个月的占1.20%,泌乳期在8个月以下的占70.8%。母犏牛泌乳期6、8、10和12个月的产奶量分别为578.5、722.6、924.1和1103.8 kg,折算成日平均产奶量分别为3.15、2.95、3.03和3.02 kg,不同泌乳期的犏牛日均产奶量比较差异不显著(P>0.05)。母犏牛在年内不同月份产奶量比较结果表明,7月和8月为一年中的产奶高峰期,分别与1-5月、11月和12月的比较差异极显著(P<0.01)。在不考虑胎次、季节和补饲的前提下,母犏牛第2~5个泌乳月为泌乳盛期,月产奶量可保持103~120 kg。其中,第3个泌乳月的产奶量为最高,显著高于第1和7个泌乳月及之后各个泌乳月的产奶量(P<0.01);根据不同泌乳月的产奶量数据建立的一元五次方程的泌乳曲线与实际产奶量的拟合度极高(R~2=0.9772)。【结论】中甸犏牛的产犊集中期为春季,其泌乳期为5~14个月,分布范围宽,日平均产奶量2.95~3.15 kg,一年中以7-8月的产奶量最高;在14个泌乳月的泌乳期中第2~5个泌乳月为泌乳盛期。

【Objective】Calving season,lactation length distribution and changes of milk production of Zhongdian cattle-yak(ZCY)were carried out to increase the milk production and provide important reference for the formulation of measures of ZCY.【Method】Based on the Shangri-La community’s cattle breeding model,142 ZCY milked every morning and evening were recorded continuously daily milk yields from the second day of calving to the milking stopped.And calving time,lactation length and milk yield in each lactation month and so on were analyzed.【Result】The percentage of calving in spring,summer,autumn and winter were 63.38%,30.99%,4.23%and 1.41%,respectively.The lactation length of ZCY cows had a wide distribution range,span from 5 months(153 d)to 14 months(427 d),and in 5 months for 24.40%,from 6 months to 8 months for 46.40%,from 9 months to 12 months for 28.0%,from 13 months to 14 months for 1.20%and less than 8 months for 70.8%.The milk yields of lactation lengths of 6,8,10 and 12 months were 578.5,722.6,924.1 and 1103.8 kg,respectively,which were converted into 3.15,2.95,3.03 and 3.02 kg of average daily milk yield,respectively,which was not a significantly difference among daily milk yields of the different lactation lengths(P>0.05);Results of comparison of milk production of ZCY cows in different months in the year showed that peak milk yield were found in July and August,and the milk yields in July and August were significantly higher than those in January,February,March,April,May,November and December,respectively(P<0.01).Regardless of parity,calving season and supplementary feeding,the higher milk yields of ZCY cows were found the second to the fifth lactation month,which were maintained milk yields of lactation month between 103 and 120 kg.And milk yield of the third lactation month reached the highest,was significantly higher than those of the milk yields in the first,seventh and its subsequent lactation months(P<0.01);According to the milk yields in different lactation months,the milk yield curve of the univariate quintic equation was established,which was high fitting degree(R2=0.9772)with the actual milk yields.【Conclusion】Rate of calving season of ZCY cows was the highest in spring,and the lactation lengths were different ranges from 5 months to 14 months,of which the distribution scope was widely;Ranges of average daily milk yield were from 2.95 to 3.15 kg,and the highest milk yields were in July and August in a year,and the peak milk yields were on the second lactation month to fifth lactation month in the lactation length of 14 lactation months.