The book explained about the effect of hormonal interventions on fertility traits of bucks. Effect of melatonin and GnRH on various external body measurements like body weight, body length, wither height and chest girth, scrotal parameters like scrotal length, scrotal diameter, scrotal circumference and sexual characteristics like reaction time, libido score, Flehmen's response, serum testosterone level and haemato-biochemical parameters were explained. Exogenous melatonin and GnRH administration increased significantly the scrotal circumference, testicular length, testicular width, reaction time and Flehmen's response in bucks. Therefore melatonin can be used in photoperiod dependent breeding animals as a new methodology to control reproduction in these species during non-breeding season. This book will be very useful for the scientists working in goat reproduction, progressive goat farmers, semen biologist, breeders and farmers in goat rearing areas for enhancement of socio-economic life of livestock owners through augmentation of breeding performance of caprine species.