author(s)
BC Naha, AK Chakravarty, MA Mir, BL Saini, P Boro and Supradip Das

abstract
Bulls are half of the herd has changed to more than half of the herd”. The birth weight is very important to breeders in judging the health of calf and its dam and also gives a good indication of the subsequent development of animal. The factors viz., period, season, breed, stage of lactation, and parity mainly affect the birth weight, age at first semen freezing and age at first semen use of breeding bulls. Age of the bull at the time of mating was the major factor influence the semen quality traits. Therefore, semen quality traits of breeding bulls is of great concern for herd profitability.