Abstracto
- In 74 weaned heifers [28 Holstein x Cebú (HC), 14 Simmental x Cebú (SC), 20 Romosinuano (R) and 12 Cebú (C)],were determined transitory rise of progesterone (ETP4), age and weight to the puberty based upon progesterone's levels (EP4; PP4) and duration of oestral cycle. The groups C (77.78 %) and R (61.11%) show a bigger incidence in ETP4 than groups SC (53.85 %) and HC (38.46 %) which apparently has improved the maturation process of the reproductive activity in the former ones, which are more efficient. The DCE is on average 18.84 days and don't exist significant differences between the racial groups assessed.
