Effect of intensive or extensive systems on buffalo heifers performances: onset of puberty and ovarian size

Abstract

The aim of this work was to determine the effect of intensive feeding (IF group) or pasture system (PS group) on the onset of puberty and on the ovarian size in buffaloes. The trial was carried out on 26 prepubertal 8-months old buffalo heifers weighing a mean of 134 kg (n =13 per group). The heifers were weighed monthly and, starting from the 13th month of age, blood samples were collected every 10 days to determine the concentration of plasma progesterone by RIA. Heifers were considered to have achieved puberty and cyclic ovarian activity when plasma progesterone levels exceeded 1 ng/ml for two samples with a lower intermediate value. After two cycles, the heifers were naturally mated. Transrectal ultrasonography was performed every twenty days to follow changes in size of ovaries and in follicles number. Significantly higher (P<0.001) gains were obtained by IF system (870 g/d) than PS one (620 g/d) but the mean age at puberty was the same in both groups ( 599d vs 610d, respectively). Within 21 months 8 (IF group) and 10 heifers (PS group) showed cyclic ovarian activity. Ovarian size increased with age in both groups; however, the length of the right ovary and the number of follicles tended to be higher in IF vs PS group.

Keywords

• Buffalo heifers, Rearing systems, Puberty, Ovary