Female response to ram effect in the Barbarine breed: Phenotypic and genetic parameter estimation

The “ram effect” has been an alternative method among many techniques to control the period of sexual activity in sheep. The objectives of this study were to (1) study the reproductive performances of the Barbarine breed in the spring, (2) to evaluate females' response to the ram effect, and estimate the phenotypic and genetic parameters of the females' response to the “ram effect”. A total of 16,150 matings of 4201 ewes recorded during a period of ten years in seven flocks was used in this study. Among these ewes 1335 have known parents and were born from 199 sires and 1053 dams. Four cyclicity traits were analyzed: spontaneous, normal, short and not answer to the ram effect. The main results show that approximately 30% of the females were cyclic out of season and more than 60% became cyclic with the “ram effect”. Flock, year and age at lambing had significant effects on the traits analyzed. A high negative phenotypic correlation of −0.75 was found between responses of normal cycles and responses of short cycle. The spontaneous ovarian activity in the spring was negatively correlated with the absence of response to a ram effect (rg = −0.44) and positively correlated to the response by a normal cycle (rg = 0.63). The correlation between responses with the normal cycle and short cycle was highly negative (rg = −0.88). For all variables, heritability was low (from 0.03 to 0.09) but significantly different from 0 and repeatability was slightly higher and varied from 0.06 to 0.1. These results indicate the great opportunity offered by the Barbarine breed for out of season breeding.