Relationship of external genitalia measurement with antral follicular count and estrus induction response in pre-pubertal Murrah buffalo heifers

This study was designed to deduce the inter-relationship between external genitalia measurement, antral follicular count (AFC) and body weight (BW) and evaluate estrus induction rate following the administration of clomiphene citrate in pre-pubertal Murrah buffalo heifers. For this study, twenty pre-pubertal heifers (age: 30-36 months; BW: 367 +/- 8.6 kg) were selected and their external genitalia along with their relative rima length (RRL) and vulval width (RVW) and AFC using trans-rectal ultrasonography were recorded. Two groups were studied: control (n=9) and treatment (n=11). Treated heifers were given clomiphene citrate at 300 mg/heifer orally for 9 days and in control group, placebo (copper sulphate tablets) were given and onset of cyclicity as well as estrus signs was detected at the end of the treatment. All the heifers showed signs of estrus, but none ovulated. Also, AFC differed between heifers with low and high RRL (6.5 +/- 0.44 vs 8.6 +/- 0.67) and RVW (6.53 +/- 0.47 vs 8.16 +/- 0.70). Likewise, BW was correlated with RRL and AFC with BW, RRL and RVW. Non-significant difference was observed between the two groups with respect to dominant and sub-ordinate I and II follicles' size. Following clomiphene citrate supplementation, crestar treatment was administered to both groups resulting in pregnancy in control animals (n=2) and treated animals (n=6). In conclusion, this study showed that BW, external genital measurements and AFC are correlated and oral administration of clomiphene citrate failed to induce fertile estrus in pre-pubertal Murrah buffalo heifers.