Poultry industry I Pakistan, has been commercialized shoeing an annual increase of 15 percent for the last ten years (Pak. Economic Analysis Network Project 1988). The poultry farming is the quickest, efficient economical and comparatively cheapest source of good quality protein. Although a considerable work has been done on various aspect of their rearing in our local environmental and managemental conditions, yet some areas remained unexplored. One of these areas was the study on comparative productive performance, qualitites and chemical composition of carcass of various commercial broiler strains, in relation to sex and age.
In the present study, four different strains and sexes of Ross, Lohmann, Indian River and Hubbard were evaluated and compared for productive performance and carcass characteristics at different age periods. A total of 240 one day old, Sex separated chicks with equal number (60) of each strain were reared for a period of 8 weeks, under indentical managemental conditions. Among male birds Hubbard gained highly significantly (P<0.01) more weight than that of other strains, while non-significant difference (P<0.05) was found between Ross and Lohamann and showed significantly better weight gain than the Indian river strain. Females birds of Hubbard strain had also gained significantly (P<0.05) more weight than that of other strains, while non significant difference was found among the females of rest of the three strains. The results on weekly feed convertion ratio were found to be non significant (P<0.05) due to strain and significant due to age of the birds . While among sexes it was found that male birds of each strain showed better F.C.R compared with that of female chicken.
The dressing percentage increased significantly with age, male birds of the strain showed better dressing percentage compared with the female birds of the respective strains though statistically the diference was found to be non-significant (P<0.05).The birds of Hubbard strain showed significantly better dressing percentage than that of the other strains. A significant difference was also observed between Lohmann and Indian River strain while the difference between Ross and Indian River was statistically non-significant as was the difference between Ross and Lohmann strain (P<0.05). The values for weight of Giblet of Ross, Lohmann and Indian River Strain were non-significantly different (P<0.05) from each other but were significantly poor than that of Hubbard strain. A non-significant difference in shank length was observed among various strains (P<0.05). Non-significant difference in length of kell bone was found among birds of Ross, Lohmann and Indian River Strain while birds of both sexes of Hubbard strain had significantly (P<0.05) greater length of kell boe. Moreover it was observed that female birds of all the strain had greater length of keal bone compared with male birds of their respective strains. Female birds of all the strain had significantly greater bone, meat ratio compared with the male birds of their respective strains. Birds of Ross. Lohmann and Indian River Strain Had significantly lesser meat bone ratio than that of Hubbard strain (P,0.05). Difference in meat bone ratio between Lohmann and Ross strain was found to be statistically significant, but non-significant between Lohmann and Indian River strains (P<0.05).
The effect of strain, age and sex on the composition of carcass revealed that moisture percentage was not significantly affected by strain and sex. However it decreased with increase in age. Crude protein contents generally increased with age in both sexes of all the four strains. Protein percentage was found to be similar between both the sexes of all strains. Fat contents increased with age In all the four strains. Female broilers of all strain had significantly greater fat contents than the male broilers (P<0.05). Between the male and female broilers Hubbard strain had significantly more fat percentage, followed by Indian River, Ross and Lohmann. There was no effect on the ash contants of carcase due to sex and strain, though it decreased with increase in age.