Comparative performance of two improved chicken breeds reared under different agro-ecologies and management Systems in Tanzania.

PhD Thesis

In recent decades the demand for poultry and livestock products has increased significantly. Likewise, poultry rearing has been adopted as a tool for poverty alleviation and has led some development agencies to promote the intensification of improved poultry systems. Two genetically improved chicken breeds (Sasso and Kuroiler) have been introduced in Tanzania as a way of improving the productivity of the poultry industry and improve people’s livelihoods. Performance of any breed is a function of both genotype and the environment in which the birds are raised. This means that breeds that perform better in one environment may not necessarily perform better in another environment. It is for this reason that Kuroiler and Sasso chickens were evaluated to establish their suitability under different agro-ecologies and management systems in Tanzania. The selected agro-ecologies in the current study were the highland and lowland areas of Mvomero district in Morogoro region, Eastern Tanzania. The two agro-ecologies were purposively selected based on their differences in temperature, altitude, vegetation type, and farming systems. Alongside, two varied management conditions i.e. on-station (controlled management) and on-farm (farmer management) conditions were also considered for performance evaluation of these breeds. The on-station study was conducted at Sokoine University of Agriculture in Morogoro region. The study was conducted to evaluate the effects of management, breeds and interaction on growth performance, egg production, egg quality and survivability. A total of 1800 day old chicks comprised of 900 Sasso and 900 Kuroiler were procured from Silverlands Tanzania in Iringa region and AKM Glitters company in Dar es Salaam region respectively. The chicks were brooded for six weeks at the Poultry farm of Sokoine University of Agriculture (SUA). Sexing of the chicks was done at end of the 6 th week.iii The birds of each breed were divided into two groups, one for on-station and the other one for on-farm evaluation. The sampling frame under farmer management (on-farm) in the two agro-ecological zones consisted of two villages per zone, 16 farmers per village and 18 birds per farmer; thus making a total of 64 farmers and 1152 birds. The farmers involved in the study were randomly selected from the list of farmers that had more than ten chickens and had been keeping chickens for at least five years. Birds were raised under a semi-scavenging system and supplemented with kitchen leftovers, maize bran, and other crop by-products in addition to scavenged feeds. For on-station study, birds were raised in six replicates per breed of 40 birds each, thus making a total of 12 pens and 480 birds. They were raised in deep litter pens and fed a commercial ration. Production traits that were evaluated and compared under both environments include growth, egg production, egg quality and survivability. The growth performance traits were body weight at 6, 8, 12, 16 and 20 weeks of age, total weight gain (TWG) and average daily gain (ADG). The traits considered for egg production were age at first egg, age at peak egg production, hen-housed egg production (HHEP), hen-day egg production (HDEP) and egg production rate. On the other hand, the quality of eggs was evaluated for eggs from both on-farm and on-station management and they involved both external traits (egg weight, length, width, shape index, shell weight, shell thickness and shell ratio) and internal traits (yolk weight, albumen weight, yolk ratio, albumen ratio, albumen height and Haugh unit). Mortalities were recorded during the growing and laying periods in both environments. Additional data for the on-station study were feed conversion ratio (FCR) and carcass traits. Evaluation of the carcass traits involved slaughtering of male chickens of the two breeds at the 16 th week of age. The traits measured were body weight ativ slaughter (BWS), carcass weight (CW) and carcass parts yield including breast, thighs, drumsticks, wings, back and neck. Data were subjected to analysis of variance using the General Linear Models (GLM) procedure of SAS software (SAS 2009), while mortality data were analyzed in accordance to frequency procedure of SAS software (SAS 2009) using a chi-square (χ2) test. Results show that agro-ecological zones differed significantly (p<0.05) with respect to growth performance and survivability. Birds raised in the highland zone were heavier (2021.7 g) than those raised in the lowland areas (1873.6 g). Similarly, birds raised in the highland zone had lower mortality rates than lowland zone during growing (12.7% vs 20.3%) and laying (34.6% vs 47.1%) periods. Significant interaction (p<0.05) between agro-ecology and breed was observed on body weight and age at sexual maturity. In the highland zone, Sasso chickens were heavier and attained sexual maturity earlier than Kuroiler while in lowland areas the performance of Kuroiler was higher than that of Sasso. With regard to management systems, the results show that management systems influenced significantly (p<0.05) all growth traits, egg production traits and survivability of chickens in favour of on-station birds. The final body weight and total egg yield (HDEP) under the on-station were 2510.9 g and 108.3 eggs, while for on-farm were 1870.5 g and 50.5 eggs in respective order. Mortality for on-station birds was lower than on-farm birds during growing (10.6% vs 22.1%) and laying ( 47.1%) 17.0%) periods. The results further showed that the mean values of egg weight, length, width, shape index, shell weight, shell thickness, yolk weight, albumen weight, albumen height and Haugh unit were also higher for on-station than on-farm while shell, yolk and albumen ratios were similar between the two management systems. Interactions between managementv and breed were significant (p<0.05) on body weight, egg weight, shell ratio and all egg production traits except peak egg production rate and mortality rate. While Sasso performance was better than that of Kuroiler on body weight and age at first egg under the on-station management system, Kuroiler was better than Sasso on those traits under the on-farm condition. For feed conversion ratio (FCR) and carcass traits, results showed that both FCR and carcass traits were influenced by breed. The FCR of Sasso was lower than that of Kuroiler. Carcass weight, dressing percentage and weight of different carcass parts were higher for Sasso than Kuroiler. Furthermore, correlations between carcass weight and carcass parts were high and positive. Based on the results of these studies, the following conclusions can be made:- i.The performance traits of the two breeds are dependent on agro-ecological zone and management systems. The chickens' performance in the highland zone appeared to be better than in the lowland in terms of growth and survivability. Similarly, on-station birds performed better than on-farm in growth performance, egg production and survival rate. ii.The response of each breed differed in some traits when subjected to different environments. Kuroiler maintained its bodyweight regardless of agro- ecology, but it matured earlier and had a lower mortality rate than Sasso in lowland areas whereas Sasso appeared better in highland than in lowland areas in growth performance, survival rate and age at sexual maturity.