Data on 26 bulls of Kankrej cattle (birth date from 2006 to 2017) inducted at a semen station from 2010 to 2020 were analyzed to study the effects of season and year of birth on age, body weight and scrotal circumference of bull at first semen collection. The overall least-squares means for age, body weight, and scrotal circumference of bulls at first semen collection were 1122.36 ± 86.9 days, 537.69 ± 10.51 kg and 30.86 ± 1.60 cm. Non-genetic factors like season and year of birth did not contribute significantly (p>0.05) to these parameters’ variations. Results of the study revealed well adaptation of Kankrej cattle breed to seasonal changes and farm management took care of yearly variation in such a way that age, body weight and scrotal circumference of Kankrej bulls at first semen collection did not vary significantly.

Semen production data comprising of 55071 ejaculates of 144 bulls from Mehsana buffalo breed was analysed. The traits under study were semen volume, sperm concentration, initial sperm motility, post-thaw sperm motility and number of semen doses per ejaculate. The objective of the present study was to assess the effect of various factors affecting semen production traits and measure the semen production potential of Mehsana buffalo bulls. Data collected of semen production traits were analysed using linear mixed model, including a random effect of bull along with fixed effect of various non-genetic factors like farm, ejaculate number, season of birth, period of birth, season of semen collection and period of semen collection. First ejaculation had higher semen volume and sperm concentration resulted in to higher number of semen doses but semen quality was better in second ejaculation. Season of birth of the bull was affecting semen quality traits. As the period of birth advances semen volume increases whereas sperm concentration decreases which reflected in persistent production of number of semen doses per ejaculate. Monsoon and summer were favorable seasons for semen collection because of higher sperm concentration which resulted in to higher semen doses per ejaculate. Additionally, Monsoon collected semen had highest volume. Hence, monsoon followed by summer season would be the favorable season for semen collection. Period of semen collection affecting all the semen production traits under study but it did not have specific trend which means managemental and environmental changes over the period have sizable influence on the traits. Results of the study will help to plan future managemental practices and breeding strategies to improve semen production traits.