The feeding experiment was conducted at Ofla district, southern Tigray, North Ethiopia, to investigate feed utilization, diet digestibility, and its economic feasibility under different supplementation options. Twenty-four yearling intact growing lambs were used in randomized complete block design with three treatments and eight replications. The treatment diets were T1 (molasses 15% + wheat bran 48% + cotton seed cake 35%), T2 (maize grain 20% + wheat bran 43% + noug seed cake 35%) and T3 (maize grain 20% + wheat bran 33% + dried brewers' grain 45%). The diet was formulated as iso-nitrogenous and each animal has taken daily nutrient requirements according to their body weight. The collected data were analyzed using SAS (2007) statistical software. Economic analysis was done using standard partial budget analysis guidelines of CIMMIT (1988). The crude protein contents of the three treatment rations were comparable across treatments. There was a higher total dry matter intake recorded in animals fed on T3 as compared to the other treatments. The barley straw intake was higher and significant (P < 0.05) for the animals' group in T3 than that of T1 and T2. Animals fed with T3 had significantly (P < 0.05) higher organic matter intake as compared to those fed with T1 and T2. However, there was no significant (P > 0.05) differences in crude protein intake between treatments. The apparent digestibility of dry matter, organic matter, and crude protein had no significant differences (P > 0.05) between treatments. Similarly, the apparent digestibility of neutral detergent fiber and acid detergent fiber was not significantly different (P > 0.05) among T1, T2, and T3. In general, animals that fed on T3 achieved better feed utilization and economic return as compared to the others.
Keywords: Barley straw; Digestibility; Feed intake; Iso-nitrogen; Supplementation; Tigray Highland sheep.