Apparent digestibility of fat and nitrogen retention in young chicks

Apparent fat digestibility and nitrogen retention were examined in broilers and laying type cockerels within the first 15 days of life. Differences be tween birds with and without deutectomy were studied as well. In chicks wit hout deutectomy, there was a rapid decrease in fat digestibility from Day 2 to Day 6 and from Day 3 to Day 7 in broiler and egg type hybrids, respecti vely. This drop was followed by an increase till Day 14. Observed changes m ay be connected with excretion of endogenous nutrients originating primaril y from the yolk sac. In deutectomized chicks, fat digestibility increased w ithin the period of Days 2 to 14. The utilisation of nitrogen in broilers w as highly significantly (P < 0.001) higher than in egg type chicks. The dep endence of coefficients of apparent nitrogen retention on the age of chicks could be expressed by means of parabola equations with the maximum values on Days 12-13. The amount of N retained in the organism per unit of weight gain increased with the increasing age.