Sexual behaviour in sheep is driven by body condition and the related nutritional and metabolic status

The sexual behaviours of ewes were only partially changed by feeding regimes. While the scores of receptivity (SR) of ewes to males (i.e. number of agonistic interactions with the courting ram) and scores of proceptivity (SP) towards rams (i.e. time spent close to a pen with rams) remained unchanged (P > 0.05), there were significant (P < 0.001) changes (Low = 2.42; Medium = 3.63 and High = 4.47; P < 0.001) in their scores of attractiveness (SA: i.e. a higher score is given to the preferred ewes by rams). This SA was well correlated with the BW (r = +0.83; P < 0.0001) and BCS (r = +0.73; P < 0.0001) of ewes, it was also negatively correlated with metabolites (NEFA: r = −0.32; P < 0.05) and positively with anabolic hormones (INS: r = +0.42; P < 0.01). Combining these variables, the SA is clearly explained (R2 = 0.79; P < 0.0001; n = 36) by a model including the static (long-term) effects of nutrition (BW and BCS) and the dynamic effects of nutrition (NEFA and INS). This work demonstrates that the nutritional status of female sheep, during oestrus, produces efficient cues that clearly orient males in their mating choices.