Two experiments with nine strains of Single Comb White Leghorn hens were conducted to compare laying house performance of hens given a diet of uniform protein content or a phase-feeding diet in which protein content was reduced from 156 to 148 and then to 140 g/kg at 273 and 414, or 273 and 384 days of age. Performance criteria were egg production, feed and protein intake, egg, quality, egg weight, mortality and body weight. Phase-feeding allowed reductions of 4.2 and 4.3% in protein consumption without reducing egg production, mortality or, except in one strain, body weight. There was an increase of 0.5% in feed consumption, but feed cost was reduced by 1.3%. Phase-feeding increased Haugh units by 0.3% and decreased specific gravity of eggs in one experiment, decreased percent visibly-cracked eggs in the other experiment and had no effect on percent blood spots. Depending on strain, phase-feeding had a variable effect on egg weight in exp. 1 but had no effect in the second experiment. Key words: Phase-feeding, protein utilization, egg production, hen
Effects of the Northern Fowl Mite, Ornithonyssus sylviarum (Canestrini and Fanzago), on Egg Quality of White Leghorn Hens
