Effects of sorghum-based diets with phytase superdosing on broiler performance

Objective The objective of this study was to evaluate the effects of sorghum-based diets with or without phytase superdosing on broiler performance.Materials and Methods A 42-d grow-out trial with 1,500 male broiler chicks that were a day old (Ross 708) was conducted. The experiment included 30 pens of 50 birds, with 10 replicate pens per treatment. The 3 dietary treatments were as follows: T1-corn-based diet with 550 phytase units (FTU)/kg phytase (standard), T2-sorghum-based diet with 550 FTU/kg phytase, and T3-sorghum-based diet with 2,000 FTU/kg phytase (superdose). The diets were formulated to be isocaloric, isonitrogenous, and to contain the same levels of available phosphorus and calcium (Ca) across all treatments. Birds were fed ad libi- tum following a phase-feeding program. Cumulative BW, BW gain, feed intake, and adjusted feed conversion ratio were calculated. One-way ANOVA followed by Fisher's LSD was used for statistical analysis. Significant differences were considered when P-values were less than 0.05, and trends were considered when P-values were between 0.1 and 0.05.Results and Discussion No differences in feed intake were observed (P > 0.05). At 14 d of age, birds fed T3 tended to gain around 6% more weight (0.368 vs. 0.346 kg) and be 3% more efficient (1.23 vs. 1.27 kg:kg) than birds fed T1 (P < 0.10). Similarly, by 21 d, birds fed the T3 diet were 2% more efficient (1.284 vs. 1.313 kg:kg; P < 0.05) and tended to gain 4% more weight than T1 birds (0.799 vs. 0.767 kg; P < 0.10). Also, at 28 d, birds fed T3 were 1.7% more efficient than those fed T1 (1.301 vs. 1.324 kg:kg; P < 0.05). Analysis of the dietary nutrient composition had 0.03% more methionine concentration in the sorghum-based diets during the starter and grower phases. This, in conjunction with the phytase superdose, might have helped birds fed T3 achieve a better nutrient uptake and, consequently, growth performance earlier in life, especially in the grower phase.Implications and Applications A full replacement of corn with American sorghum is possible without negatively affecting bird performance, and phytase superdosing in sorghum-based diets might help birds to achieve better performance.