Effect of calcium levels, appetite enhancers and endoparasites on egg shell quality and performance of laying hens

Vita.Economy of egg production is greatly affected by the quality of the egg shell and its ability ot withstand shock and resist breakage. The egg industry loses no less than 250 million dollars annually because of egg breakage caused by poor egg shell quality. Finding a remedy to correct poor shell quality and improve the egg's shell texture becomes a prime objective of interested scientists and the egg industry. So far researchers have not managed to find a solution for the egg shell problem. This study has investigated, in four consecutive experiments, the influence of modified pre-lay and laying dietary calcium regimes on the performance of commercial White Leghorn-type laying hens and the quality of their egg shell. In the first experiment 600 pullet chicks were fed five grower diets that were similar, but varying only in their calcium and phosphorus levels ranging from 0.358% calcium and 0.479% phosphorus to 1.014% calcium and 0.581% phosphorus. There were no statistically significant differences between the calcium treatments for body weight at 8, 16 and 18 weeks of age and daily feed consumption. When 20 weeks of age, the pullets in experiment I were divided in to 2 equal groups of 42 pellets per pre-lay treatment and caged one and two birds per cage. This became experiment II