Evaluation of growth performance of Sasso and Kuroiler chickens fed three diets at varying levels of supplementation under semi-intensive system of production in Tanzania.

The experiment was conducted to evaluate the effect of breed, diet, and level of feed supplementation on growth performance, feed conversion ratio, and survivability of Sasso and Kuroiler chicken. The study was conducted in two separate phases, i.e., the starter phase (0-6 weeks of age) and grower phase (6-20 weeks of age). One thousand sixty-day-old Sasso and Kuroiler chicks were raised until 6 weeks under intensive management system with three dietary treatments. At the age of 6 weeks, a total of 960 birds (480 Sasso and 480 Kuroiler) were randomly selected from each treatment diet and assigned to four feed supplementation levels, i.e., 25%, 50%, 75%, and 100% with two replicates each having 20 birds. Beginning week 7, birds were allowed to semi-scavenge from 6:00 am in the morning to 6:00 pm in the evening with free access to open grass area of 1 bird/4 m. Grower rations based on the three categories, i.e., commercial, medium-cost, and low-cost formulation, were fed from 7th to the 20th week of age. During 0 to 6 weeks of the growing phase, the breed and diet significantly (p < 0.05) influenced 6-week live weight, live weight gain, and feed conversion ratio. Birds given commercial diet (D1) excelled in live weight, total live weight gains, and feed conversion ratio followed by medium-cost (D2) and low-cost (D3) diet respectively. During the 7th to 20th weeks of the growing phase, the breed, diet, and supplementation levels had a significant influence (p < 0.05) on the live weight and weight gain at 20 weeks of age. Feed cost per kilogram gain increased with an increase in the level of supplementation. Days taken by birds to reach market weight (2 kg) with 100%, 75%, 50%, and 25% level of dietary supplementation were 16, 18, 20, and more than 20 weeks respectively. The survival rate for Sasso and Kuroiler was 99.80% and 97.13% respectively. It is concluded that appreciable growth performance can be attained for semi-scavenging Sasso and Kuroiler chickens when supplemented with medium- or low-cost diets at the level of 50 to 75% of their daily feed requirements.