Increased fecundity resulting from semen donor selection based upon in vitro sperm motility

Semen donors were selected from a population of 100 roosters based upon the extent to which sperm penetrated 6% (wt/vol) Accudenz from an overlay of extended semen. Semen donors categorized by average or high sperm motility (n = 5 per phenotype) were ejaculated weekly, their ejaculates pooled by phenotype, and pooled semen extended. A subsample of each sperm suspension was overlaid on 6% (wt/vol) Accudenz in a cuvette, the cuvette was placed in a 41 C water bath, and the absorbance of the Accudenz layer was measured after a 5-min incubation. The remainder of the sperm suspension was inseminated (n = 55 hens per phenotype). Each hen was inseminated weekly with 50 x 10(6) sperm for 14 wk. The hatchability of eggs laid by hens inseminated with sperm from the high motility phenotype was 10% greater (P < or = 0.001) than that of hens inseminated with sperm from the average phenotype. The difference in fecundity was explicable in terms of fertility (P < or = 0.001). A replicate experiment tested the effect of sperm motility as well as insemination dose on fertility. Roosters were treated as above, and hens (n = 41 to 45 per phenotype) were inseminated weekly with 25, 50, or 100 x 10(6) sperm per hen for 3 wk. Two-way ANOVA detected a sperm motility effect (P < or = 0.0001) but did not detect a dose effect (P > or = 0.05) or a motility by dose interaction (P > or = 0.05). A posteriori comparison among means revealed that the maximal fertility obtained with sperm from average roosters was 9% less (P < or = 0.05) than that obtained with only 25% as many sperm from the high motility phenotype. These experiments demonstrated that the fecundity of artificially inseminated hens can be increased when sperm penetration of Accudenz is used as a selection criterion for semen donors.