产后20天应用氯前列烯醇对分娩期和产后期异常奶牛繁殖指标的影响

本试验选用276头高产中国荷斯坦牛为研究对象，其中120头初产奶牛和156头经产奶牛均表现为分娩期异常或产后期异常，如难产、胎衣不下、双胎难产、早产或子宫感染。试验牛被分为处理组与对照组。处理组在产后20d间隔811连续两次皮下注射氯前列烯醇（0.4mg/次），对照组注射4．0mL灭菌生理盐水。然后观察其首次发情的时间、适合第一次人工授精的时间、首次授精妊娠率、150d妊娠率、产后的空怀天数、重复配种奶牛的比例和每头牛的授精次数。结果表明，产后应用前列腺素对产后首次发情的时间和产后首次人工授精的时间没有影响，但处理组奶牛首次人工授精的妊娠率明显升高，这在头胎牛更为明显；产后应用氯前列烯醇可明显减少平均授精次数、缩短产后空怀时间、增加产后150d泌乳奶牛的妊娠率、降低产犊后重复配种率。

Effect of Cloprostenol Treatment on Reproductive Indexes on Day 20 Postpartum in Dairy Cows with Calving and Puerperal Dysfunction

A total of 276 Chinese Holstein cows （120 primiparous and 156 multiparous） were selected based on the presence of at least one of calving and puerperal dysfunctions （dystocia, retained placenta, twin, abortion, and postpartum uterine infections） and were assigned to two groups （treatment and control）. Cows in the treatment group were treated twice with 0.4 mg Cloprostenol 8h apart on day 20 postpartum, and normal saline 4.0 mL in the control group. Then to record reproductive variables included days to first estrus, days to first AI, first service conception rate, pregnancy rate by 150 days in milk, open days, the incidence rate of repeat breeder cows, and service per conception. The results indicated that on day 20 postpartum Cloprostenol treatment had no effects on days to first estrus and days to first AI, but it increased first service conception rate （P〈0.01）, which was more significant in primiparous cows. Cloprostenol treatment decreased the mean service per conception and the mean open days, and increased pregnancy rate by 150 days in milk （P〈0.01）. The prevalence of repeat breeder syndrome in cows with calving and puerperal dysfunction was significantly reduced by Cloprostenol treatment （P〈0.01）. In conclusion, treatmnt of cows with calving and puerperal dysfunction twice with Cloprostenol at 8h- interval on day 20 postpartum improved reproductive indexes and reduced the incidence of repeat breeder cows.