ABSTRACT

1. The objective of this study was to investigate the effect of multi-carbohydrase enzymes (MC) on net energy (NE), performance and gene expression in Cobb 500 broilers fed diets containing different levels of soluble and total arabinoxylan (sAX/tAX) ratios.

2. The study employed a 2 × 3 factorial arrangement of treatments, with factors including with or without MC and three ratios of sAX/tAX: high (HS, 27.3%), intermediate (IS, 21.3%) and low (LS, 15.7%).

3. Six dietary treatments were formulated, with each diet replicated five times in the calorimetric study (Experiment 1) and eight times for a floor pen feeding trial (Experiment 2).

4. Experiment 1 showed significant (P < 0.01) MC × sAX/tAX interactions for apparent metabolisable energy (AME) and NE. These interactions indicated that the supplemental MC increased AME only in the HS diet, and NE in the HS and LS diets.

5. Experiment 2 results showed MC × sAX/tAX interactions for feed conversion ratio (FCR, P < 0.01) and ileal digesta viscosity (P < 0.05), demonstrating that MC lowered FCR only in the LS-fed birds, and reduced digesta viscosity only in the HS-fed birds. Apparent ileal digestible crude protein (AID CP) was negatively correlated with ileal digesta viscosity (r = −0.735, P < 0.001), which suggested that increasing ileal digesta viscosity reduced AID CP.

6. A significant (P < 0.05) MC × sAX/tAX interaction was observed for duodenal COX III mRNA gene expression, which indicated that this gene was upregulated in the IS-fed birds relative to the HS-fed birds, but only when MC was added. This gene was downregulated (P < 0.05) in the muscle in the presence of MC application in all diets.

7. The results from this study showed that supplemental MC can improve NE and FCR in birds fed diets containing the low sAX/tAX ratios.

摘要

1. 本研究的目的是研究多糖酶 (MC) 对 Cobb 500 肉鸡饲喂含有不同水平可溶性和总阿拉伯木聚糖 (sAX/tAX) 的日粮的净能量 (NE)、性能和基因表达的影响比率。

2. 该研究采用 2 × 3 因子排列的治疗方法，包括有或没有 MC 和 sAX/tAX 三个比率：高（HS，27.3%）、中（IS，21.3%）和低（LS，15.7 %）。

3. 制定了六种日粮处理，每种日粮在量热研究（实验 1）中重复 5 次，在地栏饲养试验中重复 8 次（实验 2）。

4. 实验 1 显示显着 (P < 0.01) MC × sAX/tAX 相互作用对于表观代谢能 (AME) 和 NE。这些相互作用表明，补充 MC 仅在 HS 饮食中增加 AME，在 HS 和 LS 饮食中增加 NE。

5. 实验 2 结果显示饲料转化率 (FCR, P < 0.01) 和回肠食糜粘度 (P < 0.05) 的 MC × sAX/tAX 相互作用，表明 MC 仅降低 LS 喂养鸡只的 FCR，并降低食糜粘度仅在 HS 喂养的鸟类中。表观回肠可消化粗蛋白（AID CP）与回肠食糜粘度呈负相关（r = -0.735，P < 0.001），这表明增加回肠食糜粘度降低了 AID CP。

6. 观察到十二指肠 COX III mRNA 基因表达显着 (P < 0.05) MC × sAX/tAX 相互作用，这表明该基因在 IS 喂养的鸟类中相对于 HS 喂养的鸟类上调，但仅当 MC加入。在所有饮食中应用 MC 的情况下，该基因在肌肉中被下调 (P < 0.05)。

7. 本研究的结果表明，补充 MC 可以改善饲喂低 sAX/tAX 比率日粮的鸡的 NE 和 FCR。