Utilization of crop residues and Agro – industrial by products by Tswana sheep fed varying energy sources and minerals

Abstract

Two experiments were conducted at Botswana University of Agriculture and Natural Resources, Sebele. In Experiment 1, twenty-five Tswana sheep were used in 3 x 2 factorial arrangements in a Complete Randomized Design to determine the effect of substituting sorghum bran with either sorghum stover or millet stover on performance of Tswana sheep. The experimental diets fed were: T1= 40% Cenchrus hay + 30% sorghum bran + 28% sunflower meal + 2% mineral premix, T2= 40% sorghum stover + 30% sorghum bran + 28% sunflower meal + 2% mineral premix , T3 = 50% sorghum stover + 20% sorghum bran + 28% sunflower meal + 2% mineral premix, T4= 40% millet stover + 30% sorghum bran + 28% sunflower meal + 2% mineral premix, T5= 50% millet stover + 20% sorghum bran + 28% sunflower meal + 2% mineral premix. The results indicated insignificant differences (p>0.05) in all the treatments on the feed intake (FI), weight gain (WG), final weight (FW), average daily gain (ADG) and feed conversion ratio (FCR) of Tswana sheep. In Experiment 2, thirtysix Tswana sheep were used in a 3 x 2 factorial arrangement in a complete randomized design to determine the effect of minerals on performance, carcass characteristics and blood and liver mineral concentration. The experimental diets were T1= Cenchrus hay (50%) + supplements with minerals(50%) , T2 = Cenchrus hay (50%) + supplements without minerals (50%) , T3 = Sorghum Stover (50%) + supplements with minerals (50%), T4= Sorghum Stover (50%) + supplements without minerals (50%) , T5 = Millet Stover (50%) + supplements with minerals (50%) , T6 = Millet Stover (50%) + supplements without minerals (50%) . The results indicated insignificant (p>0.05)treatment effects on FI, WG, FW, ADG, FCR, carcass weight, chuck blade weight, flank weight, leg weight, neck weight, breast weight and femur length of Tswana sheep. The data showed that Tswana sheep fed diets T1, T3 and T5 differed (p<0.05) significantly from those fed diets T2, T4 and T6 in both blood and liver Ca, P, Mg and Na concentrations. The result also showed that Tswana sheep fed diets T1, T3 and T5 differed from those fed diets T2, T4 and T6 in effect on the blood and liver Cu, Fe, Zn and Mn concentrations. In general, it was concluded that millet and sorghum stover can positively substitute sorghum bran without any significant effect on performance characteristic of Tswana sheep. Minerals supplementation was also emphasised to be included in Tswana sheep diet in order to avert minerals deficiencies