title:   THE EFFECTS OF EXOGENOUS ENZYME SUPPLEMENTATION ON THE PERFORMANCE, BONE QUALITY, AND NUTRIENT UTILIZATION OF BROILER CHICKENS
Creators: name: Bauer, Megan
Publisher: name: University of Kentucky Libraries
Year: 2023
Subjects: classificationCode: 4.2
subject: FOS: Animal and dairy science

description: Two experiments were conducted to examine the effects of Allzyme® Spectrum supplementation to a reduced nutrient diet on the growth performance, energy and nutrient digestibility and utilization, bone quality, and jejunal digesta viscosity in broiler chickens. Each experiment used 300 one-day old Cobb by-product breeder chicks with 5 treatments, 10 replicates, and 6 birds per replicate cage in a randomized complete block design. The only differences between the two experiments were experiment 1 lasted for 21 days using a corn-soybean meal-based diet and experiment 2 lasted for 22 days using a wheat-soybean meal-based diet. The 5 treatments included a positive control (PC) diet that met or exceeded nutrient Ca (0.8%) and avP (0.4%) and energy (3,050 kcal/kg) requirements of birds of this age, a negative control (NC) diet that consisted of a reduction of 90 kcal/kg ME and 0.15%-point less Ca and P, and the last 3 treatments were varying inclusion levels of Allzyme® Spectrum (150, 200, 250 g/ton, respectively) added to the NC diet. Allzyme® Spectrum (Alltech, Inc., Nicholasville, KY, USA) is an enzyme complex containing xylanase and phytase. Data were analyzed using the GLM procedures of SAS (v 9.4). Simple contrasts were used to compare the PC vs. NC diet and PC vs. enzyme supplemented diets. A post-hoc test was used to generate the coefficients for the polynomial contrasts. Orthogonal polynomial contrasts were used to compare increasing levels of enzyme supplementation on the performance, jejunal digesta viscosity, nutrient digestibility and utilization, and bone mineralization of chickens. In experiment 1, increasing levels of enzyme supplementation resulted in a quadratic increase (P < 0.05) in feed intake (FI), body weight gain (BWG) and feed efficiency (FE) d 9-21 and a linear increase (P < 0.05) in FI d 9-21 and 0-21 and FE d 0-9, 9-21, and 0-21. In experiment 2, FI of chickens from d 9-22 and 0-22 and FE d 9-22 linearly increased (P < 0.05) with increasing level of supplemental Allzyme® Spectrum. There was a quadratic effect (P < 0.05) of enzyme supplementation level on BWG d 9-22 and 0-22 and FE d 9-22 and 0-22. In experiment 2, increasing levels of enzyme supplementation resulted in both a quadratic and linear decrease (P < 0.001) in jejunal digesta viscosity. In both studies, increasing levels of enzyme supplementation resulted in a quadratic increase (P < 0.05) in dry matter and N digestibility and retention as well as, digestible and metabolizable energy and a linear increase (P < 0.05) in P and Ca digestibility. Increasing enzyme supplementation resulted in both a quadratic and linear increase (P < 0.001) in P and Ca utilization in experiment 1, however it only resulted in a linear increase (P < 0.001) in Ca and P utilization in experiment 2. In experiment 1, there was a quadratic increase (P < 0.01) in ileal digestibility of all the amino acids with increasing level of enzyme supplementation. In experiment 2, there was a quadratic increase (P < 0.05) in ileal digestibility of Arg, His, and Val and nonessential amino acids (excluding Glu: P = 0.069 and Tyr: P = 0.088) and a linear increase (P = 0.001) in ileal digestibility of Thr when comparing the enzyme supplemented diets. There was a quadratic increase (P < 0.05) with increasing levels of enzyme supplementation in bone breaking strength and bone ash in both studies. In conclusion, Allzyme® Spectrum supplementation improved growth performance, energy and nutrient digestibility and utilization, and bone mineralization in broiler chickens and reduced jejunal digesta viscosity in 21- and 22-day-old broiler chickens fed wheat-based diets.
description: 2023 Megan Bauer