Comparison Study of Carcass Traits in Roosters Resulted From Different Local Lines and Their Crosses With ISA Brown
The present study was conducted at Gardarash station, College of Agriculture, University of Salahaddien in collaboration with Hawler Research Station, Directorate of Agricultural Research�Erbil, Ministry of Agriculture during June and July, 2014. A total of 125 roosters aged 6 to 7 months were belong to three local lines and their crosses with 2 (ISA brown). Birds were starved overnight, thereafter weighed and slaughtered. Carcass yield was considered the hot eviscerated carcass weight, without feet, head and abdominal fat, in relation to the live body weight. Dressing percentage was calculated as a percentage of carcass weight in relation to live weight. The cuts including thigh, breast, back, wings and neck were considered as the percentage of their weight in relation to their carcass weight, while the giblets including liver, heart and gizzard were calculated as a percentage of their weight in relation to their live body weight. About 80-90 g, were taken from each of thigh and breast of three roosters from each genetic group, aged six months in order to estimate proximate analysis. General Linear Model within the statistical program SAS was used to study the effect of genetic groups on traits mentioned above.
The results showed that there were significant differences between the genetic groups of roosters in their live body weight, carcass weight and dressing percentage, and their overall mean were 2445.60 (g), 1965.62 (g) and 80.32 % respectively. Also significant differences were recorded among genetic groups of roosters in the percentages of their carcass parts which include thigh, breast, back, wing and neck percentages and their averages were 16.16%, 20.12%, 22.45%, 5.34% and 5.28% respectively. It was found that there were significant differences among genetic groups in liver and heart percentages only. The differences due to genetic groups in the percentages of chemical composition traits in thigh of roosters which include protein, fat, moisture and ash % were significant and their overall mean were 79.99, 9.31, 74.79 and 3.87 % respectively. Protein and moisture percentages in breast affected significantly by genetic groups of roosters, while the differences in fat and ash percentages were not significant, and the averages were 81.89, 2.89, 73.70 and 4.10 % for protein, fat, moisture and ash respectively.
Conclusion: According the above results, the roosters must be selected according to their body weight to be parents for the next generation in order to have chicks with high meat quality. It will be very important to conduct other studies using different ages and sexes.
Keywords� Poultry Genetic Groups, Carcass Traits, Chemical Composition.