Effect of Levels and Sources of Dietary Protein in Pullet Grower Diet on Subsequent Performance

An experiment was conducted using 1,100 White Leghorn pullets to study the effect of two dietary protein levels (12 and 15%) from 12–20 weeks of age on subsequent laying performance. The effect of replacing protein concentrates such as soybean meal and meat and bone meal with triticale or alfalfa (dehydrated or sun-cured) was studied. The effect of adding lysine or methionine or both to grower diets in which cereal grains were the only sources of protein on growth and subsequent performance was also studied. The performance criteria were body weight, feed consumption, egg production, egg weight, age at 50% production rate and mortality. Compared with pullets fed 12% protein grower diets, those fed 15% protein grower diets were heavier by 15 and 14 g. per bird at 20 and 32 weeks of age, respectively. The latter consumed 0.8 and 2.5 g. more feed per bird per day during the 12–20 and 21–32 week period, respectively. Pullets fed the higher protein grower diet laid 1.8% more eggs on a hen-day basis and their eggs were 0.1 g. heavier during the 23–32 week period than those of pullets fed the lower protein diet. There was a difference of 1.7 days when the two groups reached 50% production. The differences for body weight at 20 weeks of age, feed consumption during the laying period and age at 50% production rate were statistically significant (P < 0.05). Replacing the protein contributed by soybean meal and meat and bone meal with grain or alfalfa in the grower diet did not cause any adverse effects on growth and subsequent performance as layers. The results also suggest that added lysine or methionine or both were not required when corn and triticale provided all of the 12 or 15% protein in the grower diets.