The effect of CA and P levels in laying diets on the bone density index, bone breaking strength, egg specific gravity, egg production, and the incidence of cage layer fatigue

Author

Ram Dhari Singh

Date of Award

8-1971

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

J.K. Bletner

Committee Members

O.E. Goff, J.T. Smith, C.C. Chamberlain

Abstract

A total of four trials involving 990 S. C. White Leghorn-type pullets were conducted to study the response of caged layers to various Ca and P levels as measured by bone density index, bone breaking strength, egg production, and egg specific gravity. An X-ray type bone densitometer was used to determine bone density index and an Allo-Kramer shear press to determine the breaking strength of tibia.

Whenever layers were fed a diet containing 1.5 percent Ca, they maintained about 50 percent egg production. Specific gravity score of their eggs and the bone density of tibia were found significantly lower than those of birds fed diets with the higher levels of Ca.

When layers were transferred to lower levels of Ca and P, egg shell quality and bone density indexes were reduced quickly. Egg production was reduced but the rate of this reduction may have been affected by the level of Ca and P in the diet prior to the feeding of the low Ca and P diets.

Transferring layers from diets containing 2.25 or 2.75 percent Ca and 0.6 percent P to diets containing 3.0 percent Ca and 0.8 percent P had no marked effects on egg production, egg specific gravity, bone density index, or bone breaking strength.

It appears that the dietary Ca requirement for egg production is less than 3.0 percent, that for high egg specific gravity it will be no more than 3.50 percent, and that for high bone density index no more than 3.0 percent. The dietary P requirement for egg production appears to be no more than 0.6 percent; that for high egg specific gravity score, 0.4 percent; and for high bone density, 0.8 percent of the diet.

Birds with symptoms of leg weakness (cage layer osteoporosis) were found in lots fed all diets. The highest incidence of this condition was in those birds fed the 1.5 percent Ca diet.

Recommended Citation

Singh, Ram Dhari, "The effect of CA and P levels in laying diets on the bone density index, bone breaking strength, egg specific gravity, egg production, and the incidence of cage layer fatigue. " PhD diss., University of Tennessee, 1971.
https://trace.tennessee.edu/utk_graddiss/8002