| heal.abstract |
Four hundred and twenty day-old broiler chicken were grown organically for 12 weeks. Equal numbers of two genotypes, i.e. a fast (Cobb) and a medium-growing (Redbro), were used. Three diets were fed: starter, grower, finisher. From the 66th week onwards performance differed significantly between the two genotypes, being better for the fast growing broilers. Overall 12 week performance was significantly higher (p < 0.0005) for the Cobb birds which exhibited lower feed conversion ratio (2.93 vs. 3.43) due to the superior growth rate (BW 3969 vs. 2799 g). Weights of cold carcass (2782 vs. 2158), breast (818 vs. 564) and legs (841 vs. 653 g) were significantly higher (p < 0.0005) for Cobb broilers, whereas the abdominal fat (78 vs. 74 g) did not differ significantly between breeds. Similarly, DM, CP and lipid content in breast and legs did not differ significantly between the two genotypes. Results suggest that the performance of a fast growing genotype under organic conditions could be better than the performance of a medium growing one, without necessarily impairing carcass quality traits. |
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