Efficacy of sperm mobility assessment in commercial flocks and the relationships of sperm mobility and insemination dose with fertility in turkeys

Our objectives were to evaluate: 1) the efficacy of the Sperm Mobility Test on commercial turkey farms, and 2) the influence of sperm mobility phenoty pe on fertility when insemination parameters are varied. In research flocks , differences in sperm mobility among toms are predictive of fertility. We wanted to test the efficacy of this sire selection test in practical, real- world situations, evaluating its usefulness in terms of assessing large num bers of toms, different strains of turkeys, and variable management practic es. Utilizing field study results, controlled studies were then conducted t o improve test parameters. For the field trials, semen from each of 405 bre eder toms (11 strains or lines) was evaluated either in duplicate (n = 285) or in triplicate (n = 120). Sperm mobility was normally distributed among all toms tested, except for one strain. Because the sperm mobility indices for toms evaluated in these field trials were higher than those observed in research flocks, the Sperm Mobility Test was modified to increase the sepa ration between high and low sperm mobility phenotypes by increasing the con centration of Accudenz.(R) To determine the effects of sperm mobility and i nsemination dose on sustained fertility through time, hens from a research flock were inseminated twice before the onset of lay with sperm from toms c lassified as high-, average-, or low-mobility in concentrations of 25 to 40 0 million sperm per artificial insemination dose, and egg fertility was eva luated over a 5-wk period. Toms with the high-mobility sperm phenotype main tained higher fertility (P < 0.05) over the 5-wk period at all insemination doses compared with toms with low-mobility sperm. Toms with high-mobility sperm sired equal numbers of poults in a sperm competition study in which n umbers favored low-mobility toms by 3:1. These results demonstrate that the Sperm Mobility Test can be used for on-farm evaluation of semen quality of toms in commercial flocks and that sperm mobility influences fertility and sire fitness.