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Effect of prelay calcium and molting on egg production in white leghorn hens

University of British Columbia

Two prelay and one molt studies were conducted to study the effect of dietary calcium supplementation and molting on subsequent egg production in White Leghorn hens. In prelay study I, the effect of 1, 2, 3.5% dietary calcium at 16, 17 and 18 weeks was studied with 1,248 pullets. There was no significant difference in egg production, egg weight or specific gravity. However there was a difference in the distribution of egg size. Revenue, total feed consumption and profit were calculated. There was higher profit from feeding a commercial prelay diet (2% calcium) at 16 weeks of age. In prelay study II, 625 chicks from two strains (H & N and Hyline ) were used to study the effect of prelay calcium on egg production. They were subjected to four treatments containing three levels of calcium (1, 2, and 3.5% ) at 16 and 17 weeks of age. There was no significant difference in egg production, egg weight or egg specific gravity . However, there was a difference in egg size. Revenue, total feed consumption and profit were calculated. Treatment 3 which involved feeding a grower diet between 16-17 weeks and a prelay diet from 17 weeks to first egg was beneficial as it had a higher profit in the Hyline strain but treatment 2 which involved feeding a prelay diet from 16 weeks to first egg was found to be beneficial in terms of profit in H&N strain. In the molt study, the same birds as in prelay study I were subjected to molting at 57 weeks of age for a period of 20 days. During the molting the birds were fed cracked corn. Five layers were sacrificed at random and their tibias and femurs were removed for measurement of calcium in the medullary bone before and after molting them. Calcium was higher in the medullary bones before molting which was due to the effect of the layer diet fed earlier. In the post molt period the hens were fed eight diets containing two levels of protein (17 and 15%), calcium (2 and 3.25%) and available phosphorus (0.32 and 0.25%). Three birds per treatment were sacrificed and the right tibia and femur analyzed for medullary bone calcium content to determine the effect of postmolt diets on medullary bone calcium. There was no significant difference in the calcium contents of medullary bone between the tibia and femur for all the treatments. However treatment 4 which supplied 17% protein, 3.25% calcium, and 0.25% phosphorus gave a higher percentage of calcium in the tibia and femur and produced more extra large eggs. There was no significant difference in egg production, egg weight or specific gravity among all treatments.

Thesis/Dissertation

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2009-03-21

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http://hdl.handle.net/2429/6330

Animal Science

University of British Columbia

UBCV

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