Semen production and semen quality of indigenous buffalo breeds under hot semiarid climatic conditions in India

Semen data comprising of 97,023 ejaculates of 197 bulls from 6 buffalo breeds were analyzed. The traits considered were as follows: ejaculate volume, sperm concentration, mass activity, initial and post-thaw motility, total sperm, and total motile sperm before and after thawing as well as a composite trait equal to the theoretical number of doses which can be produced from each given ejaculate. The objective was to measure the semen production potential of indigenous buffalo bulls and identify factors affecting these traits. A linear mixed model was used, including a random bull effect along with other fixed factors: the order of the ejaculate on a particular day, the interval between collections, the time of collection, the breed, the age at collection, the semen collector, and the year and month of collection. The study showed breed wise variation for all traits. The first ejaculate of a bull on a particular day was superior to the second for nearly all the traits. Longer collection intervals are better than shorter intervals for all the parameters, although short collection interval of 2 to 4 days produced higher yield in terms of total semen doses without hampering semen quality. The study also showed a slight decrease of semen quality with time of collection within a day. The Murrah breed showed comparatively consistent performance during their whole life compared with the other breeds. Repeatability estimates for semen traits were found to be low (0.09 for mass activity) to relatively large (> 0.4 for volume and concentration). A negative correlation was found between bull effects for semen volume and concentration while a high positive correlation was found between mass activity, initial motility, and post-thaw motility. Results of the study will help in suggesting suitable management and breeding plans for semen production traits.