Reproductive performance response to the male effect in goats is improved when doe live weight/body condition score is increasing

Abstract

This study examines the nutritional and metabolic cue-induced modulation of the reproductive performance response of female goats to the male effect. During natural anoestrus, 48 Blanca Andaluza does were isolated from bucks for 45 days and distributed into two groups: (1) low body weight (BW)/low body condition score (BCS) animals (LL-gain group, N=18), which were fed 1.9 times their maintenance requirements; and (2) high BW/high BCS animals (HH-loss group, N=30), which were fed 0.4 times their maintenance requirements. Following isolation, oestrous activity was recorded daily by visual observation of the marks left by harness-equipped males. Weekly blood samples were taken for the determination of progesterone, glucose, insulin, non-esterified fatty acids (NEFAs) and leptin concentrations. Fecundity, fertility, prolificacy and productivity were also determined. Significantly greater ovarian and oestrous responses, and productivity, were observed in the LL-gain group compared to the HH-loss group (P<0.05). After the introduction to the males, no differences in NEFA concentration were seen between the groups; before introduction the values were higher in the HH-loss group. At the moment of detection of oestrus following male introduction, the insulin concentration of the LL-gain animals was higher (P<0.05). The present results show that the reproductive performances of does subjected to the male effect in spring are poorer in those with a decreasing BW and BCS and better in those with increasing scores. This might be explained by the differences between groups in terms of their plasma insulin concentrations. The NEFA concentration was clearly modified by introduction to the males.