Two-Way Selection for Serum Alkaline Phosphatase in Laying Hens

Abstract

The effectiveness of two way selection for serum alkaline phosphatase (S.A.P.) was investigated to determine its influence on productive traits in a White Leghorn population for three generations. The difference between females in the high and low lines at the end of three generations was 53 percent of the S.A.P. level of the foundation population. Selection was based entirely on phenotypic differences. The divergence of the lines was significant and greater in the high line. Computed heritabilities from within sire dam offspring regression for S.A.P. was .42. Heritability estimates from the analysis of variance sire component was .12 ± .09, and from the dam component .76 ±.16. The realized heritability was .45 and .36 for high and low lines respectively.No correlated responses were found during the time of this study for hen day egg production, egg weight, specific gravity or mortality. Hatchability decreased significantly in the high line and fertility decreased significantly in the low line.A build up of phosphatase in the blood occurred during the formation of the egg which would be an indication that the enzyme is involved in egg shell formation.