The Effect of the Length of Time in Production and Stage of Egg Formation on Certain Egg Quality Measurements and Blood Constituents of Laying Hens

Abstract

THE seasonal decrease in egg shell quality (Jull, 1924; and Wilhelm, 1940), and the decrease in interior egg quality with increasing age of the bird (Knox and Godfrey, 1938; and Dawson et al., 1951) are problems which confront poultry breeders and commercial poultrymen. At least two theories have been advanced to explain the decline in shell quality. One theory proposes that the decrease is due to increased environmental temperatures. Another theory proposes that the decrease in shell quality is simply an exhaustion effect coming at the end of the laying year. There are considerable data which show that blood calcium and phosphorus levels are associated with egg formation. Riddle and Reinhart (1926), Hughes et al. (1927), Roepke and Hughes (1935), Taylor and Russell (1935), Correll and Hughes (1935) and Deobald et al. (1938) reported that the blood calcium level greatly increases as birds come into production. Deobald et al. (1938) …