Effect of β-mannanase supplementation in low-energy diets containing palm kernel meal on productive performance, egg quality, intestinal morphology, and liver characteristics in laying hens raised under heat stress conditions

초록

This study aimed to investigate the effect of &#x3b2;-mannanase (MN) supplementation in low-energy diets containing palm kernel meal (PKM) on productive performance, egg quality, intestinal morphology, and liver characteristics in laying hens under heat stress (HS) conditions. Four hundred 37-wk-old Hy-Line Brown laying hens were randomly allotted to 5 dietary treatments with 8 replicates for 8 wks of the feeding trial conducted under a cyclic HS condition. The positive control (PC) diet was prepared, whereas the low-energy negative control (NC) diet was formulated to contain decreased AMEn by 100 kcal/kg than PC diets. An additional low-energy diet was prepared by including 5.0% PKM, and it was supplemented with either 0.05% or 0.10% MN. Feeding low-energy diets containing PKM increased (p < 0.05) feed conversion ratio (FCR), but MN supplementation did not affect FCR in laying hens under HS conditions. Egg yolk color was improved (p < 0.05) by feeding low-energy diets containing PKM, regardless of MN supplementation with no differences in other egg quality among treatments. The supplementation of 0.10% MN in PKM-containing low-energy diets showed lower (p < 0.05) blood heterophil to lymphocyte ratio (H:L) ratio than NC diets, but exert blood H:L ratio comparable to PC diets. A linear trend for increased villus height (VH) was observed (p < 0.05) by increasing MN supplementation in PKM-containing low-energy diets with the greatest VH was found in 0.10% MN supplementation. Feeding low-energy diets containing 5.0% PKM decreased feed efficiency in laying hens under HS conditions. However, MN supplementation in PKM-containing low-energy diets had no beneficial effects on laying performance. Low-energy diets, irrespective of PKM inclusion, exacerbate stress responses and impair jejunal morphology. However, 0.10% MN supplementation in PKM-containing low-energy diets ameliorated stress responses and improved jejunal morphology in laying hens under HS conditions.

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