Evaluation of production performance and meat quality of Tanzanian local chicken reared under intensive and semi-intensive systems of production

Abstract

Local chicken farmers can improve the performance and quality of indigenous chicken meat by modifying the production systems and age at slaughter. However, in Tanzania there is paucity of information on effect of production systems and age at slaughter of local chicken on growth performance, carcass characteristics and meat quality. The effects of rearing systems, sex and age at slaughter on growth performance, carcass traits, meat tenderness, cooking loss and pH of Tanzanian local chicken were investigated. Ninety six local weaned chicks (two months old) were bought from farmers in Morogoro peri-urban and raised in two different rearing system viz. intensive and semi-intensive systems. The birds were initially weighed and randomly assigned to each rearing system with equal number of males and females (48 birds per system); and were housed in deep litter pens with a spacing of 4 birds/m2. Birds under semi-intensive system had free access to grassy paddock (1 bird/10 m2). In both groups, birds were given a diet containing 19% CP and 2679 KJ ME with semi-intensive birds getting half of the amount given to intensive birds. At the end of the experiment, a random sample of 24 males and 24 females in each rearing system were slaughtered at five and seven month and carcass parts viz. breast, thigh and drumstick separated. Pieces of meat from these parts were used for tenderness, cooking loss and pH evaluations. The results showed that body weights at slaughter and body weight gain of birds from semi-intensive system were significantly lower than those kept in intensive system. There was no difference in dressing percentage between the two rearing systems, the values being 65.2% and 65.7% for intensive and semi-intensive respectively. Dressing percentage was higher (67.7%) at seven month than at five month of age (63.2%). The rearing system significantly affected the breast percentage, being higher in semi-intensive (25.1%) compared to intensive system (23.3%). Thigh percentage was not influenced by rearing system or slaughter age, while drum stick percentage was significantly lower at seven month old bird compared to five month old birds. There was no significant difference in breast, thigh and drumstick meat tenderness for birds reared under intensive and semi-intensive systems. Meat from chicken slaughtered at seven month was much tougher (43.9N) than meat from birds slaughtered at five month age (26.5N). The cooking loss of male breast and thigh meat under intensive system were significantly lower than that of birds under semi intensive system. Likewise, higher cooking losses were obtained for birds slaughtered at seven month (21%) compared to birds slaughtered at five month (10%). Rearing systems did not influence meat pH, though female breast under semi intensive system tended to have higher pH values (6.05) than those under intensive system (5.96). There was also an increase in pH value of male thigh and drumstick meat with advanced slaughter age. From the study, it is concluded that local chicken with modest supplementation and assuming availability of scavenging feed resources, semi-confinement system of chicken rearing could be more appropriate for the small holder poultry keepers. Meat tenderness, cooking loss and pH values from both systems were of acceptable standard however, the overall quality of meat was reduced with increased age at slaughter. Thus, to attain tender meat farmers should strive to improve management of their birds to reach slaughter weights at younger age.