Varying apparent metabolizable energy concentrations and protease supplementation affected broiler performance and jejunal and ileal digestibility from 1 to 35 d of age

Authors: McCafferty, Klint; MORGAN, NATALIE - University Of New England; COWIESON, AARON - Dsm Nutritional Products, Ltd; CHOCT, MINGAN - University Of New England; MOSS, AMY - University Of New England

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2022
Publication Date: 6/7/2022
Citation: Mccafferty, K.W., Morgan, N., Cowieson, A., Choct, M., Moss, A. 2022. Varying apparent metabolizable energy concentrations and protease supplementation affected broiler performance and jejunal and ileal digestibility from 1 to 35 d of age. Poultry Science. 101:101911. https://doi.org/10.1016/j.psj.2022.101911.
DOI: https://doi.org/10.1016/j.psj.2022.101911

Interpretive Summary: Commercial broiler diets may include feed enzymes, such as protease, due to their positive effects on growth performance and nutrient utilization. Protease enzymes have primarily been observed to increase protein and amino acid digestibility in broilers, but additional improvements in energy utilization have also been reported. This study was conducted to evaluate the effects of supplemental protease in diets with varying concentrations of metabolizable energy on broiler growth performance and nutrient digestibility during a 5-week production period. Results from this experiment demonstrated that both metabolizable energy concentrations and supplemental protease independently affected early growth performance of broilers. Nutrient digestibility was mainly affected by the concentration of metabolizable energy, which indicates that the benefits of protease supplementation on broiler growth may be due to improvements in energy partitioning rather than direct effects on nutrient digestibility. This information is important for nutritionists at broiler production facilities, universities, and feed companies for determining the value of supplemental protease and metabolizable energy concentrations on broiler growth performance and nutrient utilization.

Technical Abstract: An experiment was conducted to evaluate the effects of varying apparent metabolizable energy (AME) concentrations and protease supplementation on broiler performance and jejunal and ileal digestibility from 1 to 35 d of age. Ross × Ross 308 broilers (n = 1,008) were equally distributed into 48 floor pens and offered 1 of 6 dietary treatments, with 8 replicate pens per treatment. Dietary treatments were arranged in a factorial manner with AME concentration (low-, moderate-, or high-AME) and protease supplementation (without or with) as the main factors. Birds and feed were weighed on 1, 15, 29, and 35 d of age to determine body weight (BW), body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR). At 15 and 29 d of age, jejunal and ileal digesta contents were collected to determine digestibility. From 1 to 15 d of age, broilers offered moderate-AME diets (P < 0.05) had a 6.7, 7.1, 4.8% higher BW, BWG, FI, respectively, and a 2.1% lower FCR compared with those offered low-AME diets. Likewise, protease supplementation increased BW and BWG by 4.3 and 4.7%, respectively, and decreased FCR by 3.4%, compared with those offered the unsupplemented diets. From 1 to 29 d of age, broilers offered high-AME diets had 2.9% lower FCR compared with those offered low-AME diets. Protease supplementation increased BW, BWG, and FI by 3.1, 3.2, and 4.2%, respectively, compared with the unsupplemented diets. Cumulatively, broilers receiving high-AME diets had a 2.9% lower (P < 0.05) FCR compared with those offered low-AME diets. Supplemental protease slightly increased (P < 0.05) FCR by 1.0% compared with those offered unsupplemented diets. Values for jejunal (15 and 29 d of age) and ileal (29 d of age) starch digestibility and jejunal N digestibility (29 d of age) were lower (P < 0.05) in broilers offered high-AME diets compared with those offered low-AME diets. In conclusion, both AME concentration and supplemental protease independently affected broiler growth performance, with responses being most apparent during the starter and grower periods, whereas digestibility measures were mainly influenced by AME concentration.