Melendez P, Donovan A, Hernandez J
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610-0136, USA.
J Dairy Sci. 2000 Mar;83(3):459-63. doi: 10.3168/jds.S0022-0302(00)74903-4.
The objective of this study was to evaluate the association between milk urea nitrogen (MUN) and risk of nonpregnancy after first breeding in a commercial dairy herd in Florida. A total of 515 and 558 cows were classified as having high (17 to 25 mg/dl) or low MUN (6 to 16 mg/dl) within 30 d before first breeding; a total of 158 (30.6%) and 189 (33.8%) cows were diagnosed as pregnant, respectively. Logistic regression was used to evaluate the association between MUN and risk of nonpregnancy controlling for other variables associated with fertility (parity, calving season, breeding season). An interaction was found showing that cows with high MUN that were bred during the summer were 18 times (OR = 17.9; 95% CI = 10.0 to 31.7) at higher risk of nonpregnancy compared to cows with low MUN that were bred during the winter.
本研究的目的是评估佛罗里达州一个商业化奶牛场中，首次配种后未怀孕风险与乳尿素氮（MUN）之间的关联。共有515头和558头奶牛在首次配种前30天内被分类为高MUN（17至25毫克/分升）或低MUN（6至16毫克/分升）；分别有158头（30.6%）和189头（33.8%）奶牛被诊断为怀孕。采用逻辑回归来评估MUN与未怀孕风险之间的关联，并对与繁殖力相关的其他变量（胎次、产犊季节、配种季节）进行控制。研究发现存在交互作用，即夏季配种的高MUN奶牛未怀孕风险比冬季配种的低MUN奶牛高18倍（比值比=17.9；95%置信区间=10.0至31.7）。
