A trial was done to study the chemical
composition of meat and egg yolk of laying hens belonging
to different genotypes reared using an organic
production system. Two commercial hybrid hens (Hy-
Line Brown and Hy-Line White 36) and 2 Italian dualpurpose
breed hens (Ermellinata di Rovigo and Robusta
Maculata) were reared from 25 to 44 wk of age.
During the experimental period (July to December),
the environmental temperature decreased from about
25 to 13°C and the RH increased from 62 to 73%. The
photoperiod was 16L:8D. Meat and egg yolks of 44-wkold
hens were analyzed. The Italian breeds showed
higher meat production and lower egg production when
compared with the hybrids. Genotype affected protein,
lipid, and ash content of breast and thigh meat. Hy-
Line White and Ermellinata di Rovigo showed the lowest
(P < 0.01) breast lipid and Hy-Line White had the
lowest (P < 0.01) thigh lipid. Hy-Line White showed
higher (P < 0.05) breast and thigh cholesterol. Genotype
affected egg yolk cholesterol, which was higher (P
< 0.01) in Italian breeds than in hybrids. The fatty acid
profiles of meat and yolk were significantly affected by
genotype. The hybrid and Robusta Maculata meat and
egg fatty acid composition may be considered to be
more favorable to human health. The results indicate
that the ability of laying hens to incorporate fatty acids
is genetically dependent and a possible interaction
between strain and environmental conditions may exist
for the absorption and utilization of dietary components