روح اله میر محمودی

Identifying prolificacy potential and determination of fetal number during pregnancy for proper care and management of the pregnant goats bearing multiple fetuses and achieving the benefits out of multiple births are essential for sustainable goat farming. Our objectives were (1) to examine prolificacy potential in goats by using pituitary response to gonadotrophin releasing hormone (GnRH) challenge test, (2) to investigate hormonal profiles for the prediction of fetal number in pregnant goats and (3) to find out the most reliable timing of blood sampling for discriminating prolificacy trait and differentiating the goats bearing single, twin and triplet fetuses. In first experiment (GnRH challenge test), plasma FSH concentrations were significantly higher (P < 0.01) among the goats belonging to triplet vs. twin vs. single kidding size groups after GnRH administration. Multivariate stepwise discriminant function analysis recognized that one blood sampling at 220 min after GnRH administration can be used to distinguish prolificacy potential in goats. In second experiment, plasma progesterone levels were significantly higher (P < 0.01) in goats bearing triplet vs. twin vs. single fetus between day 84 and 21 prior to parturition. Plasma estrone sulphate concentrations were found to be higher (P < 0.05) in does bearing multiple fetuses than the does bearing single fetus between day 126 and 28 prior to parturition. A single blood sampling at day 63 prior to parturition was the most probable suitable time for discriminating kidding size by using plasma progesterone as marker.