Effects of glutamine supplementation on performance, mucosal enzymes and intestinal characteristics in broilers

This study investigates the effects of glutamine (Gln) on growth, ileal nutrient digestibility, the activity of enzymes involved in metabolism and energy production, gastrointestinal characteristics in broilers. Day-old broilers (n=480) were randomly allocated to six dietary treatments, and fed on a common basal diet either alone (CON), or supplemented with glutamine at 0.2 (Gln-0.2), 0.4 (Gln-0.4), 0.6 (Gln-0.6), 0.8 (Gln-0.8), 1.0 (Gln-1.0) per cent levels for a 42-d period. The results showed that the FCR during the grower and overall periods improved (P<0.05) with Gln compared to control. The apparent ileal digestibility of DM, OM, CP, GE were higher (P<0.05) for birds supplemented with Gln in Gln-0.6, Gln-0.8 and Gln-1.0 groups than for control and Gln-0.2 groups. The brush border membranebound alkaline phosphatase activity of broilers in the Gln-0.8 and Gln-1.0 groups were higher (P<0.05) than that of broilers in the control, Gln-0.2, and Gln-0.4 groups at d 21 and 42 of the study. In addition, there were significant differences on the aspartate aminotransferase activities between groups Gln-1.0 and control at d 21 (P<0.05). The activities of alanine aminotransferase was significantly (P<0.05) higher in groups Gln-0.6, Gln-0.8, and Gln-1.0 as compared to the control group at d 21. Moreover, the activities of glutamine synthetase in groups Gln-0.8 and Gln-1.0 were lower (P<0.05) than control groups at d 42. The activities of ALT for groups Gln-0.8 and Gln-1.0 were significantly higher (P<0.05) than that of the control groups at d 42. The activities of pyruvate kinase in Gln-0.8 and Gln-1.0 groups were lower than the control group (P<0.05), Gln-0.2, Gln-0.4, and Gln-0.6 groups at d 42. Birds in the Gln-1.0 group had the greatest villi height, and deepest crypts (P<0.05). It is concluded that supplementation of glutamine at 1.0% level improved FCR, enhanced the apparent ileal digestibility of, and increased enzyme activities related to glutamine metabolism possibly due to improvement of intestinal structure and function in broilers.