Genetic relationship between cyclic ovarian activity in heifers and cows and beef traits in males

Records were collected in an experimental herd over an 11-year period from purebred Charolais heifers (n = 351), cows (n = 615) and young entire bulls (n = 383). The objective of the study was to estimate the genetic relation ship between the components of female ovarian activity (age at puberty and postpartum anoestrus length), their growth rate and body condition score an d beef traits measured on related bulls. Two methods were used to estimate age at puberty and postpartum anoestrus length: the detection of oestrous b ehaviour and a test of cyclicity based on plasmatic progesterone assay. Thi s study shows the existence of significant heritability estimates for the d ifferent cyclicity traits (h(2) between 0.11 and 0.38). Most of the genetic correlation coefficients between ovarian activity and growth rate of femal es and males are negative and favourable (r(g) between -0.43 and 0.06). Cyc licity is also favourably related with body condition score in young or adu lt females (r(g) between -0.65 and -0.22). The genetic relationship between female ovarian activity and proportion of adipose tissue in the male carca ss is, however, close to zero. These results show that an antagonism betwee n male beef traits measured in this study and female ovarian activity is un likely to be a cause for concern in the short term.