Efecto de la eCG administrada en vacas en anestro sin cría al pie tratadas con un dispositivo intravaginal con progesterona sobre el porcentaje de preñez a la IATF

RODRIGUEZ PÉRSICO, J.; ESPERANZA, G.; ARAGÓN, M.A.; CALLEJAS, S.

Capital Federal

Congreso; Primer Congreso de la Sociedad Latinoamericana de Reproducción Animal; 2015

Sociedad Latinoamericana de Reproducción Animal

The objective of the study was to evaluate the effect of i.m. administration of equine chorionic gonadotropin (eCG) on pregnancy rate in anestrous weaned cows receiving fixed-time artificial insemination (FTAI) while grazing natural pastures. Ultrasonography examinations were performed on Day 0 in order to determine the absence of a CL (anestrous). Thus, two hundred 90-days-weaned Braford cows were selected and received a progesterone (P4) intravaginal device (0.558 g P4) plus 2 mg estradiol benzoate i.m. On Day 8, the intravaginal device was removed and 150 µg D-Cloprostenol plus 1 mg estradiol cipionate were both i.m. administrated. Cows were homogenously assigned (according to follicular diameter on Day 0 and body condition score, BCS) to receive 400 IU of eCG (eCG Group; n=100) or not receive (Control Group; n=100). FTAI were performed on Day 10 between 49 and 54 hours after intravaginal device removal. BCS was scored (1-9 scale) on Day 0 and at Day 49, both times by the same veterinarian. Twelve cows were excluded from the analysis.The effect of treatment on pregnancy rate within each category of evolution of the BCS (maintained or gain body condition) was evaluated (SAS). eCG treatment increased fertility (P=0,03) in cows that maintained BCS, 65,1% (n=63) vs. 45,9% (n=61), eCG vs. Control, respectively. No effect was found on pregnancy (P>0,05) when cows gain BCS [69,0% (n=29) vs. 71,4% (n=35), eCG vs. Control, respectively]. In conclusion, pregnancy rate at FTAI can be improved in anestrous weaned cows that maintained their BCS while grazing natural pastures.