Effects of Age on Muscular Growth and Meat Characteristics in Cobb-500 and Ross Broiler Chicken

Abstract

This experiment was undertaken to show the effects of age on muscular growth and meat characteristics in Cobb-500 and Ross broiler chicken. A total of 288 live birds of both strains were randomly collected from 16 different broiler farm of Dinajpur, Rangpur and Nilphamari districts at D1, D7, Dis, Dn, D2g and Ds5. The live birds were carried to the Anatomy and Histology laboratory of Hajee Mohammad Danesh Science and Technology University, Dinajpur, where the weight of live birds, carcass, major cut portions (breast, thigh and drumsticks), and total fat were measured by using electric balance. A part of those Anatomic structures were preserved, processed, sectioned and stained for histological study as well as the detection inter- and intra-muscular fat deposition, adipocytes and collagen content, myofiber and adipocyte thickness. All the collected data were calculated by one sample t-test and then transferred to analytical software SPSS (Version 11.5) for analysis. The average highest live weight at Dss was recorded 1860.1816.29g in Cobb-500 and 1640.47+7.57g in Ross broiler strains. The average carcasses weights at Di, D7, Dis, Dn, D2g and Dss were recorded as 14.90 +0.53g, 27.8540.30g, 85.3140.82g, 211.9444.31g, 618.36 +0.92g and 1289.0545.39g¢ for Cobb-500 and in case of Ross strains 12.89+0.41g, 25.8340.38g, 82.09+0.35g, 210.5842.66¢g, 565.5542.41¢ and 1133.8043.51g, respectively. Differences in dressing percentages (DP) between Cobb-500 and Ross strains were found statistically significant (P<0.01) at Di, D7, Dis and non significant (P>0.05) at Dx, Dzg and Dss. Highest DP was recorded at Dss which was 69.2940.11¢ in Cobb-500 and 69.12+0.12 in Ross strains. At Di, D7, Dis, Du, D2g and Dss heaviest breast, thighs and drumsticks were recorded in Cobb-500 in comparison to those of Ross broiler but higher lean: bone ratio at D7, Dn and Dss and lower fat (%) at Di, Du, Dzg and Dss were recorded in Ross strain. The length, breadth, thickness and weight of pectoralis thoracis, supracoracoideus, iliotibialis lateralis, iliotibialis cranialis, biceps brachii and triceps brachii muscles were higher in Cobb-500 at every studied age. Histologically, the collagen content was lower in breast and thigh muscles at Dz and thigh muscle at Dss of Ross strain. More intramuscular fat and thicker adipocyte were found in Cobb-500. The myocytes were thinner in breast muscle and thicker in thigh muscle at D2g and Dss of Cobb-500 strain in comparison to those of Ross strain. In conclusion, for unique muscular growth Cobb-500 may be recommended for small scale farming system and for better meat quality Ross may be suggested to meat industries and consumers.