THE COMBINED EFFECT OF A HIGH CALCIUM PRE-LAY DIET, A HIGH PROTEIN LAYER DIET AND SUPPLEMENTAL OYSTER SHELL ON EGG SPECIFIC GRAVITY AND OTHER BIOLOGICAL TRAITS OF SINGLE COMB WHITE LEGHORN HENS

Abstract

Three experiments, involving 1728 adult Leghorns (Starcross 288), were designed to study the combined effects of grower diet calcium level (3.26 vs. 0.80%) fed from 105 to 147 days and the feeding of supplementary oyster shell and a high protein diet (20.1 vs. 15.1%) from 147 to 497 days of age, on shell strength (egg specific gravity) and other performance traits. In exps. 1 and 2 the hens were housed in individual cages and two birds per cage, respectively, while in exp. 3 birds were housed in floor pens. The feeding of supplementary oyster shell during the laying period had little effect on mortality, egg production, egg weight, body weights or feed consumed per dozen eggs produced. Birds fed the high protein diet were heavier toward the end of the laying period compared with birds fed the low protein diet in the three experiments. Birds fed the high protein diet laid larger sized eggs but this was significant (P < 0.05) only in exp. 1. The high protein layer diet coupled with supplementary oyster shell feeding resulted in improved eggshell strength. In comparison with the low calcium grower diet, the high calcium grower diet did not statistically (P < 0.05) improve shell strength. Key words: Eggshell strength, diets, protein, calcium, Leghorn, poultry