Mahnani Abolfazl, Sadeghi-Sefidmazgi Ali, Ansari-Mahyari Saeid, Ghorbani Gholam-Reza, Keshavarzi Hamideh
Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, PO Box 84156-83111, Isfahan, Iran.
Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, PO Box 84156-83111, Isfahan, Iran.
Theriogenology. 2021 Jan 1;159:87-97. doi: 10.1016/j.theriogenology.2020.10.007. Epub 2020 Oct 11.
Risk factors for retained placenta (RP), as a common and economically important disorder, have been widely investigated. However, comprehensive studies are rare. Therefore, this study sought to identify herd-cow factors and their interactions on the risk of RP in Iranian dairy herds. The data were collected from nine Holstein dairy herds in Isfahan province, Iran. The final dataset included 154,048 records for 59,610 cows which calved between March 2011 and December 2018. A logistic regression model was used to separately analyze the risk factors and their interactions for RP in primiparous and multiparous cows. The average rate of RP was 12.3% (9.0-15.4%) at the herd level. The highest rate of RP was recorded in spring compared with other seasons. Regardless of calving season, occurrence of dystocia, stillbirth and twinning increased the odds ratio (OR) of RP. In primiparous cows, occurrence of dystocia and stillbirth increased OR of RP 4.30 and 3.33 times, respectively. In multiparous cows, dystocia, twinning and stillbirth increased OR of RP 4.36, 3.94 and 1.29 times, respectively. Cows with an age at first calving of >28 months had the highest rate of RP compared with other cows. Multiparous and primiparous cows with a short (less than 271 d) and long (more than 281 d) pregnancy, respectively, had the highest risk of RP compared to cows in other groups. Furthermore, multiparous cows with an extended dry period length (more than 75 d) and produced milk yield more than 13,000 kg/lactation were at higher risk of RP with an average of 13.5%. With an interaction analysis, although the potential effect of each factors depends on the effect of other factors, but in general dystocia, stillbirth, an extended age at first calving (>28 months), and calving during the spring increased risk of RP for both groups. In conclusion, identification of risk factors for RP with an interaction analysis can help farm managers to employ the best strategies to reduce the occurrence of this reproductive disorder.
胎盘滞留（RP）作为一种常见且具有经济重要性的疾病，其风险因素已得到广泛研究。然而，全面的研究却很少见。因此，本研究旨在确定伊朗奶牛群中与RP风险相关的畜群 - 奶牛因素及其相互作用。数据收集自伊朗伊斯法罕省的9个荷斯坦奶牛群。最终数据集包括2011年3月至2018年12月期间产犊的59610头奶牛的154048条记录。使用逻辑回归模型分别分析初产和经产奶牛中RP的风险因素及其相互作用。在畜群水平上，RP的平均发生率为12.3%（9.0 - 15.4%）。与其他季节相比，春季的RP发生率最高。无论产犊季节如何，难产、死产和双胎的发生都会增加RP的比值比（OR）。在初产奶牛中，难产和死产使RP的OR分别增加4.30倍和3.33倍。在经产奶牛中，难产、双胎和死产使RP的OR分别增加4.36倍、3.94倍和1.29倍。首次产犊年龄>28个月的奶牛与其他奶牛相比，RP发生率最高。初产和经产奶牛分别在怀孕期短（少于271天）和长（超过281天）时，与其他组奶牛相比，RP风险最高。此外，干奶期延长（超过75天）且泌乳期产奶量超过13000千克的经产奶牛患RP的风险更高，平均为13.5%。通过交互分析，虽然每个因素的潜在影响取决于其他因素的影响，但总体而言，难产、死产、首次产犊年龄延长（>28个月）以及春季产犊会增加两组奶牛患RP的风险。总之，通过交互分析确定RP的风险因素可以帮助农场管理者采用最佳策略来减少这种繁殖障碍的发生。
