School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
J Dairy Sci. 2020 Oct;103(10):9493-9501. doi: 10.3168/jds.2019-17974. Epub 2020 Jul 23.
The first aim of this study was to evaluate the relationship between the concentrations of plasma insulin-like growth factor-I (IGF-I) in the transition period and the incidence of clinical endometritis postpartum. The second aim was to evaluate the relationship between the concentration of plasma IGF-I in the transition period and the estrous synchrony response and pregnancy rate to a controlled internal drug release (CIDR) protocol. A total of 402 dairy cows, 250 multiparous and 152 primiparous, were enrolled. A blood sample was taken from all cows 2 and 1 wk precalving and wk 1, 3, 4, and 5 postcalving for subsequent analysis of IGF-I. Vaginal discharge score as a measurement of uterine health was recorded in wk 3, 4, and 5 postcalving. Estrous cycles of all cows were synchronized on ≥37 d in milk (mean = 59; range 37-93) using an 8-d CIDR protocol. All cows were scanned at 32 to 35 d after insemination to confirm pregnancy. Data were analyzed using Proc Mixed and Proc Logistic models in SAS (version 9.3; SAS Institute Inc., Cary, NC). Plasma IGF-I concentrations were significantly greater in the primiparous cows than in the multiparous cows, both before and after calving, and were therefore analyzed separately. In multiparous cows plasma IGF-I concentrations postcalving were significantly lower among cows with uterine infection than in those without infection, and multiparous cows with a plasma IGF-I concentration less than 40 ng/mL 1 wk after calving were 3 times more likely to suffer from a uterine infection 4 to 5 weeks postcalving (odds ratio 2.8; 95% confidence interval 1.0-7.6). Plasma IGF-I concentrations were significantly greater after calving in the 121 primiparous cows that exhibited estrus post-CIDR protocol (mean 125 ng/mL) than in the 25 primiparous cows that did not respond (mean 95 ng/mL). Multiparous cows with greater plasma IGF-I concentrations postcalving had a significantly greater chance of conceiving (mean plasma IGF-I concentration of conceiving cows = 86 ng/mL; nonconceiving = 70 ng/mL). These results show an association between greater concentrations of plasma IGF-I postcalving and response to CIDR protocol in primiparous animals (mean plasma IGF-I concentration of responders = 116 ng/mL; nonresponders = 95 ng/mL). In contrast no association was detected between concentrations of plasma IGF-I in relation to the response to the CIDR protocol in multiparous cows. In conclusion, changes in circulating concentrations of plasma IGF-I early postpartum may help predict reproductive status of dairy cows.
本研究的首要目的是评估围产期血浆胰岛素样生长因子-I（IGF-I）浓度与产后临床子宫内膜炎发病的关系。其次，评估围产期血浆 IGF-I 浓度与控制内部药物释放（CIDR）方案的发情同步反应和妊娠率的关系。共纳入 402 头奶牛，其中 250 头为经产牛，152 头为初产牛。所有奶牛在产前 2 周和产前 1 周、产后 1、3、4 和 5 周采血，随后分析 IGF-I。产后第 3、4 和 5 周记录阴道分泌物评分作为子宫健康的测量指标。所有奶牛均在产奶后≥37 天（平均 59 天；范围 37-93 天）使用 8 天 CIDR 方案同步发情。所有奶牛均在授精后 32-35 天进行扫描以确认妊娠。数据使用 SAS（版本 9.3；SAS Institute Inc.，Cary，NC）中的 Proc Mixed 和 Proc Logistic 模型进行分析。初产牛的血浆 IGF-I 浓度显著高于经产牛，无论是产前还是产后，因此分别进行分析。产后，感染子宫的奶牛的血浆 IGF-I 浓度明显低于未感染的奶牛，产后 1 周 IGF-I 浓度低于 40ng/ml 的经产奶牛，4-5 周后发生子宫感染的可能性高 3 倍（比值比 2.8；95%置信区间 1.0-7.6）。CIDR 方案后发情的 121 头初产牛的产后 IGF-I 浓度显著高于未发情的 25 头初产牛（平均 125ng/ml）。产后 IGF-I 浓度较高的经产奶牛怀孕的可能性显著增加（平均血浆 IGF-I 浓度为怀孕牛=86ng/ml；未怀孕牛=70ng/ml）。这些结果表明，产后较高的 IGF-I 浓度与初产动物对 CIDR 方案的反应之间存在关联（反应者的平均血浆 IGF-I 浓度=116ng/ml；非反应者=95ng/ml）。相比之下，未发现经产牛的血浆 IGF-I 浓度与对 CIDR 方案的反应之间存在关联。总之，产后早期循环血浆 IGF-I 浓度的变化可能有助于预测奶牛的繁殖状态。
