Repeatability Estimates For Seminal Traits And Their Phenotypic Relationships With Testes Measurements And Performance Traits In Black Bengal Buck

Abstract

Repeatability for seminal traits and their phenotypic relationships with testes measurements and performance traits in Black Bengal bucks were estimated from a total of 116 repeated observations on 15 young Black Bengal bucks. Performance traits included age, body condition and body weight of bucks. Testes measurements were testes length, breadth and volume, and scrotal circumference, while seminal traits were ejaculate volume, semen density, mass activity, sperm motility, sperm concentration, total sperm per ejaculation and percent of normal sperm. High positive correlations (ranging from 0.81 to 0.90) were found between body weight and testes measurements. Semen volume and percent of normal sperm were positively correlated with age, body condition and body weight of bucks (ranging from 0.24 to 0.60). The testes measurements were strongly and positively correlated with semen volume and total sperm per ejaculation (ranging from 0.53 to 0.61), while the correlations between testes measurement and percent of normal sperm were moderate (ranging from 0.34 to 0.44). Among seminal traits, strong correlations were found between semen volume and total sperm per ejaculation (0.81) and, between mass activity and sperm motility (0.82). Repeatability of ejaculate volume was higher (r = 0.78) which indicated that selection or culling for semen ejaculate volume could be practiced from single or few observations. It could be concluded that bucks’ age, body weight and body condition along with testes volume should be considered as selection criteria for improving semen quality and semen production of breeding bucks. DOI: http://dx.doi.org/10.3329/bjas.v37i2.9879 BJAS 2008; 37(2): 34-41