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.