泌乳阶段与产奶季节对初产奶牛牛乳体细胞数的影响

为探究初产奶牛牛乳体细胞数在不同泌乳阶段和产奶季节的变化规律，旨在为采取合理措施降低牛乳体细胞数和改善乳品质提供理论依据，研究以2012年5月至2013年4月期间选择2126头初产奶牛13168条DHI测定记录，以泌乳阶段和产奶季节及其两者的互作作为研究因子，分析泌乳阶段和产奶季节及其互作对初产奶牛牛乳体细胞数（SCC）变化规律的影响。结果表明，泌乳阶段和产奶季节及其互作对体细胞数评分（SCS）具有极显著的影响（P〈0．0001）。初产奶牛于泌乳早期牛乳SCC较高（294．16×10^3个／mL），随着泌乳月龄的增加，SCC逐渐降低，泌乳中期（192．71×10^3个／mL）和泌乳晚期（185．51×10^3个／mL）牛乳SCC基本保持稳定；初产奶牛泌乳早期牛乳SCS比泌乳中期和泌乳晚期极显著升高（P〈0．01）；初产奶牛牛乳SCC冬季最高（312．72×10^3个／mL），春季次之（236．48×10^3个／mL），秋季最低（168．59×10^3个／mL）；初产奶牛冬春季牛乳SCS比夏秋季极显著升高（P〈0．01）。奶牛乳中体细胞数受胎次、泌乳月龄、产奶季节等因素的影响。产奶季节对SCC的影响主要反映了温度和湿度因素对奶牛的影响。

Effect of Lactation Stage and Season on Somatic Cell Count for First-calving Cattle

To probe into the change pattern of somatic cell count （See） of first-calving cattle in terms of different lactation stages and seasons and to guide people to take reasonable measures to reduce see and improve milk quality, Dairy Herd Improvement （DHI） data comprising 13168 records from 2126 first-cal ving cattle, collected during May, 2012 to April, 2013 were used to analyze the effect of lactation stage and season and their interaction on see. Lactation stage and season and their interaction were analyzed as factors. The results showed that lactation stage and season and their interaction had extremely significant effects on somatic cell score （ses）. see was higher at the beginning of lactation （first,second, third lac tation month） and tended to decrease along the lactation month and remained basically stable later（294. 16 ×10^3 /mL, 192.71 ×10^3 /mL and 185. 51 ×10^3 /mU; ses in early lactation was higher than that in medium and late lactationsC2. 98 scores,2. 57 scores and Z. 55 scores）; see was the highest in winter, medium in spring and lowest in autumn（312. 72X103/mL,236. 48X103个/mL and 168. 5 ×10^3 /mU; ses in spring and winter was extremely higher than that in summer and autumn（P〈O. 01）. Itwas concluded that see was influenced by parity, milk month and lactation season. Lactation season affected see mainly and reflected the influence of temperature and humidity on dairy cows.