Evaluating phytase activity and amino acid density as suitable on-farm nutrient segregation markers: Effects on broiler performance, processing yields, and bone mineralization

Pellet quality and feed line length influence the nutrient density in feed pans throughout poultry houses. Reported variability in amino acid density (AAD) and phytase activity (PhyAct) along feed lines prompted this investigation. The objectives were to determine the impact of nutrient segregation, as measured in a controlled field trial, on broiler performance, processing yields, and bone mineralization in a replicated pen trial. Dietary treatments were arranged in a 2 × 3 factorial in a randomized complete block design. Ross 308 male broilers were provided diets varying in AAD (95 % and 105 % of recommendation) and PhyAct (250, 500, 750 FTU/kg) from d11-38. Experimental diets were given full nutrient release credit for phytase at 500 FTU/kg; however, the phytase was withheld at the mill. Liquid phytase was later mixed into diets to create the PhyAct levels. Broiler performance and bone mineralization were measured from d11-38 while processing yields were determined on d39. The main effects of AAD and PhyAct did not interact (P > 0.05). However, broilers fed excess AAD improved d38 BW by 121 g, overall FCR by 0.077, and breast yield by 1.056 % compared to those fed reduced AAD (P < 0.05). Conversely, the main effect of PhyAct did not affect measured parameters (P > 0.05). While variability in both AAD and PhyAct can be identified in the field, these data demonstrated that AAD is a suitable marker for nutrient segregation that impacts performance. The lack of broiler performance differences makes PhyAct (500 FTU/kg dose) a poor nutrient segregation marker.