Attributes of broiler breeder males characterized by low and high sperm mobility

The attributes of broiler breeder males characterized by sperm mobility phenotype were studied in replicate experiments. Low and high phenotypes were observed in the first experiment over a 10-wk interval. Average straight line velocity differed between phenotypes (P < or = 0.05) as evidenced by computer-assisted sperm motion analysis. The second experiment compared low and high phenotypes from the same broiler breeder strain over a 29-wk interval. Body weight and fertility were measured in this experiment. Body weight data approximated parallel lines. The low phenotype averaged 227 g more than the high phenotype over the course of the experiment. Individual males were used as semen donors at 50, 54, 58, 62, and 65 wk of age. Eggs were collected for 2 wk after a single insemination at each age. Mean overall fertility (+/- SEM) was 44 +/- 4 and 69 +/- 2% for low and high sperm mobility phenotypes, respectively (P < or = 0.0001). As determined by transmission electron microscopy, the percentage of sperm with aberrant mitochondria was greater for the low sperm mobility phenotype (P < or = 0.0001). Neither blood plasma testosterone concentration nor testis weight differed between phenotypes. Sperm mobility is a biologically significant predictor of broiler breeder semen quality. The relationship between sperm mobility phenotype and body weight warrants further investigation.