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An experiment was conducted to investigate the effect of corn apparent metabolizable energy (AME) value, on broiler performance associated with geographical location (source), xylanase inclusion, and formulation. A 3 (corn source) × 2 (formulation; adjusted or non-adjusted value) × 2 (xylanase inclusion, 0 vs 16,000 BXU/kg) factorial randomized complete block desig study was conducted which included 10 replicates of 20 male broilers per replicate for a 42 d experiment. In the non-adjusted corn diets, each dietary treatment contained the same percentage of each corn source while the adjusted corn diets formulated based on a corn near-infrared (NIR) nutrient analysis and AME prediction equation (AB Vista, Marlborough, UK). In all cases, the predicted AME of the corns was lower than the NRC (1994) AME value, resulting in additional fat inclusion. The dietary program consisted of 3 dietary phases; starter (d 1 to 18), grower (d 19 to 33), and finisher (d 34 to 42) with growth performance monitored at feed changes. Xylanase increased (p < 0.05) starter feed consumption and d 18 body weight (BW) (2.1%), and an increase in BW (4.6%) was observed using the predicted AME values. Corn source continued to impact broiler performance throughout the remainder of the trial as corn source A consistently outperformed (p < 0.05) corn source C with increased BW and reduced mortality corrected FCR. Dietary adjustment with AME predicted values for each corn source consistently improved (p < 0.05) growth performance. Corn source A had the highest average BW with a 2.9% increase (p < 0.05) over corn source C. Early feed conversion rate (FCR) was improved (p < 0.05) with the predicted AME value diet-fed broilers, decreasing FCR by 3%. Multiple significant interactions were observed between the corn source and the adjustment method. For example, with d 42 FCR, using the predicted AME value adjustment had an impact of 9 and 10 points for corn source B and C, respectively, but only 2 for corn source A. This experiment demonstrates the impact of variable corn nutrient content and the potential improvement when using NIR technology for ingredient nutrient specifications.

The objective of the current study was to evaluate the effect of feeding a thermo-tolerant xylanase in low-energy broiler diets on performance and processing parameters. Evaluation criteria included average broiler BW, FCR, livability, carcass yield, and fat pad yields. The experimental design consisted of 3 nutrient profiles: positive control, negative control 1 (−66 kcal/kg), and negative control 2 (−132 kcal/kg). Two xylanase inclusion programs were included in the negative control 1 and 2 diets; 60 g/t was included in the starter and grower diets with either 60 or 100 g/t in the finisher and withdrawal diets, yielding a total of 7 treatment groups with 8 replicate pens per treatment each containing 42-d-old straight-run chicks per treatment (2,352 total broilers). Broilers were reared in floor pens through 45 d of age. The dietary program consisted of 5 dietary phases: starter (1–15 d), grower 1 (16–23 d), grower 2 (24–31 d), finisher (32–38 d), and withdrawal (39–45 d). Body weights and feed consumption were determined on days of dietary changes, including d 15, 23, 31, 38, and 45. On d 45, 4 male and 4 female broilers per replicate (448 total) were subjected to an 8-h feed withdrawal period and processed to obtain carcass and fat pad weights. Reducing the dietary energy level increased FCR and decreased the fat pad weight of broilers in the negative control 2 treatment compared with the positive control. Inclusion of xylanase during the starter phase increased d 15 BW and reduced FCR. The inclusion of xylanase continued to reduce FCR throughout the trial, as compared with diets without xylanase inclusion. Within this study, we have demonstrated the effectiveness of xylanase inclusion in reduced-energy diets (−66 and −132 kcal/kg) to improve FCR of broilers to that of broilers fed energy-adequate diets.