| This experiment was conducted to investigate the effect of glutamine on growth performance of 21 days weaning piglets, and approach the mechanism from internal secretion levels, small intestine morphology, tissue DNA content, T lymphocyte proliferation and differentiation rate, serum immunoglobulin levels and so on.One hundred twenty piglets weaned at 21 d age were randomly assigned to four groups( 10 piglets per pen, 3 pens per group). In all treaments, piglets received the corn-and soybean meal-based diets supplemented with 0.0,0.5,1.0 or 1.5% free L-glutamine.The diarrhea rate of piglets in glutamine treatments had quicker reduce than that of in control from day 9 postweaning. Compared with glutamine groups, the control had higher diarrhea rate and had longer diarrhea periods. The control piglets had 50-60% diarrhea rate on d 8-11 postweaning and still occurred 20-30% diarrhea rate on d 12-15 postweaning.During the first ten days postweaning, glutamine had no effect (P>0.05) on average daily feed intake and average daily gain. However, the feed:gain ratio of pigs supplemented with 0.5%, 1.0% and 1.5%Gln was 14.00% (P<0.05), 12.05% (P<0.05) and 9.13% (P>0.05) lower respectively than that of control. During the second ten days postweaning, average daily gain of glutamine treatments increased 21.39% (P>0.05), 27.75% (P<0.05) and 12.72% (P>0.05) respectively than that of control, and average daily feed intake increased 4.89%(P>0.05) , 12.70%(P>0.05) and 9.77%(P>0.05) respectively, but had no effect on the feed:gain ratio. From d 20 to d 30 postweaning, glutamine had no effects on feed intake, average daily gain and the feed:gain ratio.Diarrhea stress induced atrophy of intestine mucous membran, the results indicated that villus height decreased significantly in all parts of the small intestine. Compared with control, the villus height of duodenum, jejunum and ileum was 13.47% (P<0.05), 13.23% (P>0.05) and 36.96% (P<0.05) higher on day 10postweanin in 1.0% Glu treatment. Between d 10 to d 20 postweaning, the villus height increased signifficantly in all parts of the small intestine, but 1.0%Gln addition in feed leaded villus height of duodenum, jejunum and ileum increasing 34.51% (P<0.05),12.83% (P<0.05) and 34.84% (P<0.05) respectively.Diarrhea stress also induced the changing of small intestine lamina propria. On the day 10 postweaning, all piglets lamina propria depth of duodenum and jejunum decreased obviously, but glutamine had no effect on lamina propria depth. Lamina propria depth of ileum in 1.0%Gln treatment was 8.72% (P<0.05) lower than that in control. On day 20 postweaning, lamina propria depth in small intestine increased significantly, but glutamine supplements had no signicantly effect. The DNA content of jejunum mucous membrane in 1.0% Glu group was 12.59% (P<0. 05)higher than that in control .On day 10 postweaning, IgG and IgM concentration of serum decreased 21.44%(P>0.05) and 28.23%(P>0.05) than those of preweaning, and IgA, IgG, IgM concentration of serum in 1.0% Gin group was 6.49% (P>0.05), 35.04% (P<0.05) and 32.58% (P<0.05) higher respectively than those in control. Supplementation Glutamine leaded higher IgA, IgG and IgM concentration in serum by 15.22%(P<0.05), 2.28%(P>0.05), 30.66%(P<0.05) than those of in control on 20th after weaning.Glutamine supplementation significantly increased the rate of T lymphocytes proliferating by 75.08%(P<0.05) in vitro. The DNA content of mesenteric lymph nodes in 1.0% Glu group was 9.18% (P<0. 05)higher than that in control . On day 10 postweaning, glutamine supplements significantly increased the activity of trypsin in duodenal content by 25.87% (P<0.05). On d 20 postweaning, the activities of trypsin and total protease in 1.0%Glu treament was 26.08% (P<0.05), 12.83%(P<0.05) higher respectively than those of in control.The results of this study implicated as follows. (1)Supplementation with 1.0% glutamine in feed can reduce the rate of piglets diarrhea and shortened the diarrhea lasting periods, it also reduced feed:gain rati...
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