Impact of seasons and management factors on seminal attributes and frozen semen doses production in Holstein Friesian crossbred dairy bulls

Abstract

Major problems with frozen semen doses (FSD) production from crossbred dairy bulls are high disposal rates due to unsatisfactory breeding soundness, sub-fertility, poor semen quality, and freezability. The study aims to evaluate, within the same genetic background of bulls, the identification of important non-genetic factors that could significantly influence semen characteristics and breeding ability. Bulls' category (FSD producer vs. no FSD producer) had significantly affected sperm and semen traits. Age significantly affected all semen attributes studied, and quality increased up to five years of age in FSD bulls, in contrast, only two years in Non-FSD bulls. The semen quality index (SQI) of Non-FSD bulls remained inferior lifelong, and five years old Non-FSD bulls SQI was even lesser than that of two years old FSD bulls. Seasons significantly influenced ejaculate characteristics, sperm productivity, and FSD production. Semen quality, sperm output, and FSD production were the highest during summer and lowest in rainy seasons. It was concluded that dependent on season, the age of the bull significantly influenced qualitative and quantitative attributes of semen; age-wise quality improvement was substantial in FSD but negligible in Non-FSD bulls after two years. The study recommended that germplasm harvest from crossbred bulls should be emphasized during the summer and winter seasons for more FSD production. Two-year-old bulls with SQI <50 should be culled immediately because their semen quality did not improve afterward. Adoption of stress amelioration during the rainy season might help increase semen quality and FSD production in crossbred bulls under tropical climatic conditions.