Caracterización de la respuesta ovárica a la superovulación en bovino Criollo Coreño utilizando dosis reducidas de FSH

Abstract

To evaluate the ovarian response to superovulation using reduced doses of FSH in Criollo Coreño cattle two experiments were conducted at the Experimental Station "El Verdineño" (INIFAP) located in Nayarit, México. Twelve (12) cows of 12.4 ± 2.9 yr old (Exp 1) and six heifers of 3.0 ± 0.3 yr old (Exp 2) were used. Three treatments were assigned to each female consisting of 280 mg (T1), 200 mg (T2) and 140 mg (T3) of FSH, so that all females received all treatments. The response variables were transferable embryos (ET), corpuscles retrieved (CR) = (embryos+non fertilized ova), degenerated embryos (ENT), number of corpora lutea (CL), non-fertilized ova (ONF), ovarian volume (VO), serum progesterone (P4), fertilization rate (%F) = ((ET+ENT)∗100)/CR) and percent recovery (%R)=CL∗100/CR. A cross-over balanced experimental design was used. Analyses were carried out with the GLM procedure of SAS. The statistical model included the fixed effects of treatment (T1, T2 and T3), animal (twelve or six) and period (three periods). In Exp 1 differences among treatments (P<0.05) favorable to T1 were detected for CR and ONF. No differences were found (P>0.05) among treatments for ET, ENT, CL, VO, P4, %F or %R. In Exp 2 no differences were detected (P>0.05) among treatments for any of the variables. It is feasible to use reduced doses of FSH for the superovulation of Criollo Coreño heifers without affecting the response to superovulation or to embryo production.