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The effect of goat nutritional condition on the response to biostimulation with sexually active males during different stages of anestrus was determined. Fifty-eight Criollo × Nubian females on high and low body mass index (BMI) diets were used. Each BMI group was divided into two for biostimulation with sexually active males during May (mid-anestrus) or July (transition period). Ovulatory responses to biostimulation were characterized from serum progesterone, as well as the delay for response (first and second ovulations followed by a normal length luteal phase, O-WNLP). The percentage of goats showing one O-WNLP was greater in the high BMI group than in the low BMI group and greater during the transition period than in the mid-anestrus. However, the interaction between factors revealed that the difference between BMI groups was only significant in the transition period and the difference between stages was only significant in goats with high BMI. Occurrence of a second O-WNLP tended to be greater in the high BMI group than in the low BMI group. Response delay was shorter in the transition period than in mid-anestrus. In conclusion, female nutritional status interacting with the stage of anestrus determined the ovulatory response to male biostimulation in crossbred Criollo goats.

RESUMENSe determinó el efecto de las reservas corporales de energía (IMC) y el consumo diario de alimento (CA), sobre la LH sérica durante las transiciones hacia época anovulatoria (TA) y reproductiva (TR). Doce cabras Criollas/ Nubia, ovariectomizadas con implantes s.c. de 17-β β β β β estradiol, se dividieron en dos grupos (n=6), uno de IMC alto (IMCA) y otro bajo (IMCB). Dentro de grupo de IMC se establecieron dos subgrupos (n=3); con restricción de alimento (CRCA) y sin restricción temporal (SRCA). Se determinó la frecuencia de pulsos (FPLH), concentración media (CMLH) y basal de LH (CBLH). Durante TA se observó disminución gradual de FPLH, CMLH y CBLH (2.08, 1.41, 0.41 pulsos/6 h; 2.1, 1.21, 0.51 ng/ml; 1.3, 0.8, 0.4 ng/ml; P<0.01). En TR aumentaron CMLH y CBLH (1.01, 1.58, 1.87 ng/ ml; 0.57, 0.98, 1.04 ng/ml; P<0.01). Cabras con IMCA presentaron mayor FPLH que las de IMCB durante TA (2.05 vs 0.55 pulsos/6 h; P<0.05) y TR (3.2 vs 0.9 pulsos/6 h; P<0.01) y mayor CMLH durante TR (2.1 vs 0.87 ng/ml; P<0.01). Durante TA, la restricción en CA provocó disminución más temprana de CMLH y CBLH en cabras con IMCA (P<0.05), haciéndolas similares a cabras con IMCB. Independientemente del IMC, durante TR la restricción en CA disminuyó FPLH y CBLH (P<0.05). En cabras criollas cruzadas, la secreción de LH es modulada por el IMC y el CA durante los periodos de transición reproductiva. A su vez durante TA, la restricción temporal en CA puede disminuir la secreción de LH aún en cabras con IMC alto.PALABRAS CLAVE: Nutrición, Estacionalidad reproductiva, Cabra. ABSTRACTThe effect of body energy reserves (BMI) and daily feed intake (FI), on serum LH during transitions into the anovulatory (AT) or breeding season (BT) was determined. Twelve ovariectomized Criollo/Nubian goats, bearing s.c. 17-β β β β β estradiol implants, were assigned to two groups of BMI (n=6): high (HBMI) and low BMI (LBMI). Within each BMI group, two subgroups (n=3) were established: with (WFIR) and without (WOFIR) temporal restriction in FI. LH pulse frequency (LHF) and mean (LHM) and basal (LHB) serum LH concentrations were determined. LHF, LHM and LHB gradually diminished during AT (2.08, 1.41, 0.41 pulses/6 h; 2.1, 1.21, 0.51 ng/ml; 1.3, 0.8, 0.4 ng/ ml; P<0.01), whereas LHM and LHB gradually increased during BT (1.01, 1.58, 1.87 ng/ml; 0.57, 0.98, 1.04 ng/ ml; P<0.01). HBMI goats had greater LHF than LBMI goats during AT (2.05 vs 0.55 pulses/6 h; P<0.05) and BT (3.2 vs 0.9 pulses/6 h; P<0.05), and also greater LHM during BT (2.1 vs 0.87 ng/ml; P<0.01). During AT, temporal feed restriction caused an earlier decrease on LHM and LHB in HBMI goats making their profile similar with LBMI goat's profile. During BT, temporal feed restriction diminished LHF and LHB independently of BMI (2.8 vs 1.3 pulses/ 6 h and 1.18 vs 0.55 ng/ml for WOFIR vs WFIR; P<0.05). Body energy reserves and daily feed intake modulate LH secretion during reproductive transitions in Criollo/Nubian goats. Moreover, temporal restriction in feed intake might diminish LH secretion during tra...