Inclusion of Extruded Sorghum [Sorghum Bicolor (L.) Moench] Meal and Exogenous Phytase Enzyme on the Performance of Broiler Chicken

Abstract

Maize grain is the main energy source in broiler diets. However, its production is scarce and expensive, making commercial broiler chicken diets expensive and unavailable, which makes broiler production not sustainable. Sorghum [Sorghum bicolor (L.) Moench] grain is identified as an alternative to maize grain in broiler diets. Sorghum is locally available, underutilized, high-value, and drought-tolerant. However, the digestibility of sorghum grain as an alternative to maize in broiler diets is constrained by anti-nutritional factors like tannins, kafirins, and phytates. This study determined the effect of extrusion cooking variables on in vitro dry matter digestibility (IVDMD) of extruded sorghum meal (ESM), the inclusion of ESM and exogenous phytase enzyme in broiler diets on performance. The first experiment determined the effect of feed moisture content (40, 45, and 50%), screw speed (280 and 300 rpm), and barrel temperature (70 and 90oC) on the IVDMD of ESM. The second experiment determined the effect of inclusion levels (0, 50, and 100%) of ESM as an energy source with or without (0 and 0.035%) exogenous phytase enzyme on broiler performance. The study used 108 mixed-sex Cobb 500® day-old broiler chicks. The chicks were weighed, grouped into six, assigned cages and each cage randomly assigned to one of the six dietary treatments. The treatments were: T1 (0% ESM + 0% phytase), T2 (0 % ESM + 0.035 % phytase), T3 (50 % ESM + 0 % phytase), T4 (50 % ESM + 0.035 % phytase), T5 (100 % ESM + 0 % phytase), and T6 (100 % ESM + 0.035 % phytase). The grower and finisher diets were offered from days 1-21 and 22-42, respectively. Weekly average daily feed intake (ADFI), average daily gain (ADG), and feed conversion ratio (FCR) were measured. The third experiment determined the carcass characteristics and descriptive sensory quality using three randomly sampled broilers per treatment after day 42. Data were subjected to analysis of variance in a completely randomized design using the general linear model procedure of the SAS Institute Inc. (version 9.4; 2015). Mean separation was done using Tukey’s HSD tests at a 0.05 level of significance. A reduction in the feed moisture content and an increase in the screw speed and barrel temperature significantly increased the IVDMD of ESM. In the grower phase, inclusion of ESM up to 50% had no significant effect on the feed conversion ratio, while the exogenous phytase enzyme improved average daily feed intake and average daily gain. Inclusion of ESM up to 50% with exogenous phytase enzyme did not affect average daily feed intake, average daily gain, feed conversion ratio, carcass characteristics and descriptive sensory quality. From the results, it was concluded that inclusion of ESM up to 50% with exogenous phytase enzyme did not adversely affect average daily feed intake, average daily gain, feed conversion ratio, carcass characteristics and descriptive sensory quality of broiler chicken.