Influence of season, age and postpartum interval on reproductive parameters of norgestomet treated anestrus zebu cattle

Abstract

The study was conducted on anestrus Zebu cattle randomly assigned either to receive Crestar treatment
(n=82: 39 heifers+ 43 cows) or to remain untreated (n=24: 12 heifers+ 12 cows) for studying the effect of age,
postpartum interval and season on their reproductive perfonnance. Reproductive perfonnance was not affected
by age of heifers (2.5 - 3.0 vs. 3 - 4 yr.) and postpartum interval (90-120 vs. 150 or more days). The encouraging
results of 71 - 100% estrus induction rate: 4 i- 72% first service conception rates and 65 - 83% overall conception
rates suggested that heifers even at younger age could possibly be induced to estrus with this treatment. provided
their physical condition are good: as well as the cows with even shorter postpartum interval. In addition, Crestar
effectively induced fertile estrus in anestrus heifers and cows both during the hot as well as the cold months. The
mean interval to estrus for heifers during hot season was significantly longer than the cold season suggesting that
heifers treated during hot months should be bred according to estrus for better fertility.