Masters Theses

Huthail Najib

Date of Award

12-1976

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

James K. Bletner

Committee Members

H. V. Shirley, J. P. Hitchcock

Abstract

The objective of this study was to determine the response of four strains of high producing Single Comb White Leghorn—type hens to two levels of dietary phosphorus as measured by egg production, egg specific gravity, egg weight, feed efficiency, mortality, and the percent tinted eggs and to study the effect of time of oviposition on egg specific gravity. The experiment was conducted for eleven 28—day periods using January hatched pullets housed at the rate of two birds per 20.3 cm. wide cage. Two diets containing two levels of phosphorus, 0.4 percent and 0.6 percent, were compared. Each was fed to four lots of 30 birds of each four strains of layers. The four strains of S. C. White Leghorn—type layers responded to the two dietary phosphorus levels in a similar manner. In only two comparisons were the differences large enough to be significant (P < 0.05). The birds of strain 4 when fed the 0.4 percent phosphorus diet laid eggs that had a specific gravity score that was significantly larger than that of the eggs of birds of the same strain fed the 0.6 percent phosphorus diet. Strain 2 birds fed the 0.4 percent phosphorus diet laid significantly more eggs with tinted shells than did birds of the same strain fed the 0.6 percent phosphorus diet. There was a marked tendency for birds of all strains to gain more body weight when fed the 0.6 percent phosphorus diet, to consume more feed and to lay fewer eggs with tinted shells. The strains differed significantly (P < 0.05) in average egg weight, initial and final body weight, and in the percent of tinted eggs laid. Analyses of the data to determine diet effects failed to identify any differences in the overall response to the diets. Eggs laid in the afternoon had higher specific gravity than those laid earlier in the day. Eggs laid between 8:00 a.m. and 10:15 a.m. and between 10:15 a.m. and 1:00 p.m. have the highest coefficients of variability but appeared to vary the least from day to day when compared with eggs laid earlier or later in the day.

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