Timed artificial insemination plus heat I: effect of estrus expression scores on pregnancy of cows subjected to progesterone–estradiol-based protocols

Autor: E. Nogueira, M.R. Silva, J.C.B. Silva, U.P.G. Abreu, N.A. Anache, K.C. Silva, C.J.T. Cardoso, P. Sutovsky, W.B. Rodrigues
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Zdroj: Animal, Vol 13, Iss 10, Pp 2305-2312 (2019)
Druh dokumentu: article
ISSN: 1751-7311
17517311
DOI: 10.1017/S1751731119000442
Popis: Expression of estrus near timed artificial insemination (TAI) is associated with greater fertility, and estrus detection could improve TAI fertility or direct TAI management, although accurate estrus detection can be difficult and time-consuming using traditional methods. The aim of this study is to evaluate influence of estrus on pregnancy (artificial insemination pregnancy rates (P/AI)) and to validate an alternative method to classify estrus/heat expression using tail chalking (HEATSC) in postpartum Bos indicus cows subjected to TAI in progesterone–estrogen-based protocols. In experiment 1 (Exp. 1), cows (5491) were subjected to visual observation of estrus after progesterone device removal, before TAI, and P/AI was evaluated according to estrus and body condition score (BCS). Cows received a progesterone device and 2 mg estradiol benzoate (EB). After 8 days, the device was removed and 150 μg of d-cloprostenol and 300 IU equine chorionic gonadotrophin was given. Later, animals in Exp. 1 received 1 mg EB and TAI 44 to 48 h. In the Exp. 2 – 3830 cows using similar protocol, received different ovulation inducers: 1 mg EB (n=1624) or 1 mg estradiol cypionate (EC; n=2206) on day 8 (D8). Cows were then marked with chalk, and HEATSC evaluated at TAI on D10 (HEATSC1 – no chalk removal=no estrus expression; HEATSC2 – partial chalk removal=low estrus expression; HEATSC3 – near complete/complete chalk removal=high estrus expression). In Exp. 1, cows showing estrus presented greater P/AI (48.4% v. 40.2%, P
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