Growth and production performance of egg-type chickens reared on modified step-up protein feeding regimens

Abstract

Eight hundred egg-type chicks were used to evaluate the effect of modified step-up feeding programs on growth from 0-20 weeks of age and production from 20-72 weeks of age. Crude protein levels of the isocaloric diets were as follows: treatment 1 (control): 18% CP from 0-6 weeks of age, 15% from 6-14 weeks and 12% from 14-20 weeks; treatment 2: 18% from 0-3 weeks, 12% from 3-8 weeks, 15% from 8-14 weeks and 18% from 14-20 weeks; treatment 3: 18% from 0-2 weeks, 12% from 2-8 weeks, same as treatment 2 thereafter; and treatment 4: 18% from 0-1 week, 12% from 1-8 weeks, and same as treatments 2 and 3 thereafter. At twenty weeks of age, 576 birds were moved into laying cages. All treatments were managed the same nutritionally and otherwise during the 52 week laying phase.

Results from the 20 week growing period indicated that the conventionally fed birds consumed significantly more feed than the birds reared in modified step-up treatments. Treatments 2 and 3 consumed significantly more protein than treatments 1 and 4. Treatment 4 consumed significantly less feed/gram body weight and was significantly lighter at 20 weeks of age than treatment 1. No significant differences for various skeletal measurements were obtained by 20 weeks. Growing mortality was not influenced by dietary treatment.

By 28 weeks of age, there were no significant body weight differences between treatments. Although treatment differences were not found to be significant for hen housed production, hen day production, livability, egg weight, grams feed/gram egg, grams feed/hen day, shell quality or Haugh unit scores over the 52 weeks of production, the numerical averages favored treatments 3 and 4. The control birds consumed significantly more feed/dozen than treatment 3 and 4 birds.