Semen production, sperm quality, and their heritabilities as influenced by selection for fertility of frozen-thawed semen in the chicken

Ejaculate volume, sperm concentration, and sperm number per ejaculate were measured six times from 8 to 15 months of age, and testes and body weight at 15 months of age, on Generation 9 males of a line of broiler breeders selected for fertility of frozen-thawed semen and those of a randombred control line. Sperm quality (percent normal, percent abnormal, and percent dead sperm) was determined on Generation 10 males at 11 months of age. Selection decreased (P less than .01) ejaculate volume and sperm number per ejaculate. The control line had 4.9% more abnormal (P less than .05) sperm than the selected line. The differences between the lines for sperm concentration, testes and body weights, and percent dead sperm were not significant (P greater than .05). The correlation coefficients of fertility of frozen-thawed semen with percent abnormal and percent dead sperm were negative but were positive with percent normal sperm. The heritability and repeatability estimates of ejaculate volume, sperm concentration, and sperm number per ejaculate ranged from .34 to .73 and .33 to .51, respectively.