Body condition and stage of seasonal anestrus interact to determine the ovulatory response after male biostimulation in anovulatory Criollo × Nubian goats

Abstract

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.

The comparison of reproductive hormone receptor expressions of the sheep ovary and hormone concentrations in two Chinese breeds

“…During follicular development, oestradiol concentrations gradually increase concomitantly with follicle diameter (Bartlewski et al, ). In anoestrus, the number and size of antral follicles in the ovary were similar to those observed during the breeding season; however, no ovulation was observed (Ravindra & Rawlings, ; Vera‐Avila et al, ). It was also reported that the anoestrous ovary can contain follicles that reach 5 mm in diameter.…”