|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|5523111||1546079||2017||5 صفحه PDF||سفارش دهید||دانلود کنید|
This study examines the possible effects on the reproductive performance of high-producing dairy cows of progesterone (P4) given in the early luteal phase (1.55Â g of P4), from Days 3 to 5 post-artificial insemination (AI) as compared with the time of pregnancy recognition, from Days 15 to 17 post-AI. Cows in their third day post-AI were alternately assigned on a weekly rotational basis to the following groups: control, no treatment (C: nÂ =Â 351), P4 treatment started 15Â days after AI (P4-D15: nÂ =Â 261), or P4 treatment started 3Â days after AI (P4-D3: nÂ =Â 203). Based on odds ratios, cows in P4-D3 were 1.71 times more likely to conceive than control cows (PÂ =Â 0.004), whereas cows in P4-D15 showed a 1.4-fold greater risk approaching significance of becoming pregnant compared with control cows (PÂ =Â 0.06). Differences were not observed between treatments. In nonpregnant cows, the given treatment (D3 vs. D15) had no effect on subsequent return to estrus or AI interval and neither were any effects of treatment observed on early fetal loss rates. In contrast, in pregnant cows, the relative risk of twin pregnancy was 2.5 times higher for those in P4-D15 (P = 0.02) than the remaining cows. These findings indicate the efficacy of P4 supplementation after AI. However, when given at the time of pregnancy recognition rather than in the early luteal phase, this treatment increases the twin pregnancy rate.
Journal: Theriogenology - Volume 90, 1 March 2017, Pages 20-24