אסיף מאגר המחקר החקלאי

Behavioral and hormonal pattern of repeat breeder cows around estrus

Year:

2015

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Authors :

Volume :

149

Co-Authors:

Sood, P., Department of Ruminant Science, Institute of Animal Sciences, Volcani Center, PO Box 6, Bet-Dagan, Israel, Department of Veterinary Gynecology and Obstetrics, DGCN College of Veterinary and Animal Sciences, Himachal Pradesh Agricultural University, Palampur, Himachal Pradesh, India
Zachut, M., Department of Ruminant Science, Institute of Animal Sciences, Volcani Center, PO Box 6, Bet-Dagan, Israel
Dube, H., Department of Ruminant Science, Institute of Animal Sciences, Volcani Center, PO Box 6, Bet-Dagan, Israel
Moallem, U., Department of Ruminant Science, Institute of Animal Sciences, Volcani Center, PO Box 6, Bet-Dagan, Israel

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Abstract:

Repeat breeder (RB) cows were compared with normal (CTRL) ones with respect to behavioral estrus intensity, endocrine patterns and concentrations of plasma estradiol, progesterone and LH around estrus, and ovulation timing. A total of 27 and 31 cycles in 12 RB and 18 CTRL cows, respectively, were synchronized by means of the Ovsynch protocol followed by a single PG injection after 7 days. Behavioral estrus and ovulation were observed in 81.5 and 83.8% of the synchronized cycles in the RB and CTRL cows respectively. The RB and CTRL groups had similar estrus durations of 21.4 and 19.6 h respectively, but estrus was more intense in the RB, as indicated by numerically higher overall activity indexes and higher peak neck activity. The interval from PG injection to estrus onset (considered as proestrus) was 8.2 h shorter in RB than in CTRL cows, at 47.9 and 56.1 h respectively (P<0.007), but the average preovulatory follicle size was similar. The estradiol concentration at peak was numerically higher (21%) and the AUC tended to be higher in the RB cows than in the CTRL cows. LH secretion during the period from 18 to 3 h before the LH peak was also lower in RB than in CTRL cows: 2.5 and 4.6 ng/ml respectively (P<0.01). In conclusion, the behavioral estrus was more intense in the RB cows; nevertheless, short proestrus and subdued LH concentrations before the LH peak, which could impair oocyte competence and development, were first reported in RB cows. © 2015 Society for Reproduction and Fertility.

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