Resumption of post partum sexual activity in suckling cattle in New-Caledonia

Abstract

The purpose of the present study was to define the characteristics of the resumption of post partum activity in cattle in New-Caledonia by determining the circulating blood levels of progesterone and by recording various production parameters. During a breeding season, 108 cows (61 Charolais and 37 Santa-Gertrudis) were subjected to three series of two blood samplings each month at 10-days intervals, from March to June. The determination of the blood level of progesterone was made by radioimmunoassay. A concentration exceeding 2 ng/ml was the threshold used to ascertain the existence of a cyclic activity. Parallel to that, the following data were recorded: weight of cows and their young every 21 days, observation of heats, recording of birth and of calving-fertilizing mating interval. Results of hormone assays showed that 10 % of the cows were cycled at 21 days, 74 % at 42 days and 100 % at 63 days. According to the statistical analysis, the breed, weight loss, milk production or age did not significantly affect the distribution of the calving-fertilizing mating interval (P >0.05). Fertilizing matings mainly occurred at the first and second cycles after the onset heats. The tropical oceanic climate of the study area did not seem to directly affect the time of resumption of sexual activity after calving. This activity mainly depended on the level of feeding of the animals prior to calving.