Avaliação da eficiência reprodutiva em bovinos de corte após a utilização da inseminação artificial seguida da transferência de embriões produzidos in vitro

Content Provider	Semantic Scholar
Author	Sanabria, German Holguin
Copyright Year	2018
Abstract	The association of timed artificial insemination (TAI) and timed embryo transfer (TET) has the potential to increase reproductive efficiency in beef cattle. This study evaluated reproductive performance in beef cattle after TAI followed by TET of IVP embryos at the onset of the breeding season. A total of 476 multiparous non-suckling Bos taurus females were estrous synchronized by the IM administration of 2 mg estradiol benzoate and the insertion of a 1 g intravaginal progesterone release device on D-11, which was removed on D-2, followed by the IM administration of 0.48 mg sodium cloprostenol, 400 IU eCG, and 0.5 mg estradiol cypionate. In Experiment I (no heat detection, or no HD, n=387), TAI was carried out 48 h later (D0), whereas in Experiment II (after HD, n=89), AI was performed 12 h after the onset of estrus up to 48 h after intravaginal insert removal, when remaining females were inseminated (D0). Day-7 blastocysts produced by IVF from abattoir-derived oocytes from beef cattle were individually transferred (TET) seven days after TAI (D7) to 186/387 and 44/89 females in Experiments I and II, respectively, into the uterine horn ipsilateral to the corpus luteum. Then, fertile mature Bos taurus bulls were introduced into the female herds (1:25) up to D90. Determination of pregnancy outcome after TAI, TAI+TET or natural mating, twinning rates, and pregnancy losses were performed by ultrasonography and rectal palpation on D30, D60 and D125, with data were analyzed by the Chi-square test (P<0.05). Birth weights, body weights at D110 and daily body weight gains up to D110 were analyzed by ANOVA and ANCOVA, with pairwise comparisons performed by the Tukey test (P <0.05). Pregnancy rates on D30 were lower in TAI (104/201, 51.7%) than TAI+TET group (126/186, 67.7%) after no HD (Experiment I), but were similar between TAI (32/45, 71.1%) and TAI+TET (30/44, 68.2%) groups after HD (Experiment II).Twinning rates were lower in TAI groups with no HD (6/97, 6,2%) and after HD (1/30, 3,3%) than TAI+TET groups with either no HD (41/125, 32,7%) or with HD (13/30, 40,7%). Overall pregnancy outcomes were similar between groups after the end of the breeding season, being 90.0% (181/201) and 90.3% (168/186) for TAI and TAI+TET with no HD, and 84.4% (38/45) and 84.1% (37/44) for TAI and TAI+TET after HD. Pregnancy losses were higher after TAI+TET with no HD (27/126, 21.4%) than TAI+TET after HD (3/30, 10.0%), and TAI with (2/32, 6.3%) or without (9/104, 8.7%) HD, with no differences observed in losses between singletonand twin-bearing pregnancies. The TAI+TET group after HD had higher number of fetuses per served (0.89) or per pregnant (1.44) female than TAI+TET with no HD (0.69 or 1.30,
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Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article