Quantification of a sperm-egg interaction for estimating the mating efficiency of broiler breeder flocks.

1. The frequency distribution of points of sperm hydrolysis (or holes) produced per unit area of the inner perivitelline layer was examined in samples of approximately 60 laid eggs, taken on the same day from each of 19 flocks of broiler breeder hens. 2. The holes counted in samples of perivitelline layer from eggs varied from 0 to greater than 100; lower numbers being found in eggs from flocks with lower fertility. 3. The median frequency of holes in the inner perivitelline layer was strongly correlated (r = 0.92) with the median frequency of spermatozoa found trapped in the corresponding outer perivitelline layer. 4. The median frequency of holes in the inner perivitelline layer and of spermatozoa in the outer perivitelline layer were both strongly correlated (r = 0.80 and 0.77, respectively) with flock fertility. 5. It is suggested that counting 'holes' in the inner perivitelline layer of laid eggs is a more convenient method for assessing breeding efficiency and predicting flock fertility than counting spermatozoa trapped in the outer perivitelline layer.