The role of dietary calcium in the control of egg production : a thesis ... for the degree of Master of Agricultural Science at Massey University

Thumbnail Image
Open Access Location
Journal Title
Journal ISSN
Volume Title
Massey University
The Author
Dietary calcium restriotion is studied as a method of controlling egg production. Attempts have been made to delay the onset of egg production in the fowl by feeding pre-laying diets deficient in calcium. Calcium restriction had no apparent effect on sexual development and did not delay the time· of first oviposition. Low calcium diets were used at a later date to halt egg production firstly just after peak production and secondly towards the end of the first laying year. Egg production was depressed markedly but never completely ceased, and remained at a low level until calcium restrictions were lifted whereupon a rapid rise returned egg production to levels comparable to egg production rates of non calcium restricted control hens. Comparisons between egg production, egg weight, shell weight and a measure of shell quality (shell weight per unit surface area of egg) revealed trends towards improved shell production and shell quality following calcium restriction but little else. There was only a small number of significant differences. Egg production pauses induced by low dietary calcium were thought to be unsatisfactory as substitutes for force moulting. Calcium restriction caused declines in food consumption and body weight. While food consumption returned to levels equivalent to food consumption of non calcium restricted hens after calcium restriction, body weight in general did not. Calculations of the calcium loss from the body of calcium restricted hens via egg·shell production show that extremely severe depletion occurs unless egg prvduction is stopped or at least egg shell production is stopped. Such depletion of calcium has greatest effects on the skeleton and damage to the bones, particularly of the legs, may result. This is a condition which may predispose to a paralytic condition characteristic of extreme calcium deficiency.
Calcium, Poultry, Egg production