关键词: 奶牛, 隐性乳房炎, 阳性率, 生产胎次, 风险因素

Abstract: [Objective]In order to understand the prevalence of recessive mastitis and analyze its possible risk factors in a large-scale dairy farm in northern Xinjiang. [Method]In the experiment,recessive mastitis was investigated in the herd cows of this farm through California Mastitis Test （CMT） in each season from 2020 to 2022,and the main risk factors that may exist in this farm were preliminarily analyzed. [Result]From 2020 to 2022,the average positive rates of recessive mastitis in dairy cows were 3.69%（110/2 980）,5.12% （150/2 993） and 3.87% （86/2 220） respectively. The positive rates in milk area were 0.93% （110/11 856）,1.35% （160/11 880） and 0.97% （86/8 860）respectively. The rates of blind nipple were 0.13%（16/11 920）,0.20% （23/11 972 and 0.23%（20/8 880） respectively. The positive rate of recessive mastitis in summer was significantly higher than that in other seasons. There was no significant difference in the positive rate of recessive mastitis in milk regions of cows（P>0.05）. The average positive rate of recessive mastitis in cows of different parity was significant（P<0.05）. The average positive rate of recessive mastitis in cows of 5 and 6 fetuses and above was significantly higher than that in other parity.[Conclusion]The incidence of recessive mastitis in dairy cows in this pasture is low,but it still needs to be improved. The hot and humid breeding environment in summer and the elderly dairy cows are more prone to heat stress,which may lead to the decline of their own immunity and other reasons,which may be the main risk factors for dairy cows in this pasture to suffer from mastitis.

Key words: cow recessive mastitis, positive rate, production parity, risk factor