Mm. Mialon et al., Genetic relationship between cyclic ovarian activity in heifers and cows and beef traits in males, GEN SEL EVO, 33(3), 2001, pp. 273-287
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.