Synthetic DL-methionine (DLM) supplements poultry diets to enhance production. The bioe cacy of liquid methionine is generally lower than that of powder methionine; however, if the level of total sulfur amino acids (TSAA) is set to the commercial recommendation, the bioe cacy of liquid methionine seems to be equal to that of powder methionine (equimolar basis). Absorption and transportation in the segment of the jejunum di er between liquid and powder methionine because multiple systems are involved. Methionine supplementation in a low-protein diet alleviates the negative e ects of heat stress. The supplementation improves the amino acid balance and consequently promotes growth performance by enhancing feed e ciency, increases protein synthesis and decreases fat synthesis. Methionine supplementation also improves the immune response through direct e ects (protein synthesis and breakdown) and indirect e ects (derivatives of methionine). As various factors influence the methionine requirement, the requirements of commercial strains are higher than those recommended by NRC ( ). Moreover, the methionine requirement expressed as a percentage of diet declines during the starter and grower phases, while the requirement related to lysine is little changed (tends to increase).

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This study was conducted to evaluate the effect of adding liquid DL-methionine hydroxy analogue free acid (LMA) to drinking water on growth performance, small intestinal morphology and volatile fatty acids in the caecum of nursery pigs. Twenty-four crossbred pigs (Large White x Landrace, BW approximately 18 kg) were divided into three groups with four replications of two piglets each. The piglets received drinking water without (control), with 0.05 or 0.10% LMA. The results indicated that adding LMA at 0.10% to drinking water significantly increased their weight gain, average daily feed intake (p < 0.05) and tended to improve the feed conversion ratio. Adding LMA to drinking water significantly increased their water intake and significantly reduced the pH of drinking water (p < 0.01), thus total plate count (p < 0.01) and Escherichia coli in drinking water was reduced (p < 0.05), while the total number of bacteria in the caecum was not significantly affected. Liquid DL-methionine hydroxy analogue free acid supplementation in drinking water tended to decrease pH in the stomach, duodenum, jejunum, colon and rectum. Furthermore, adding LMA at 0.10% significantly increased villous height in the duodenum, jejunum and ileum (p < 0.05), and the villous height:crypt depth ratio in the jejunum and ileum (p < 0.01) was higher, whereas acetic acid concentration in the caecum was significantly lower than in the control group. It could be concluded that adding LMA to drinking water improved growth performance of the nursery pigs because of high water quality and high nutrient utilization caused by an improvement of small intestinal morphology (not from nutritional effect of methionine source).

This study was conducted to compare the effects of dietary supplementation of Sodium Gluconate (SG), Mannan Oligosaccharide (MOS) and Potassium Diformate (PDF) on growth performance and small intestinal morphology in nursery piglets. One hundred forty four female piglets (11.69±0.71 kg) were divided into 4 treatments with six replicates of six pigs each. The pigs received a control diet or diets supplemented with SG, MOS and PDF at 2,500, 3,000 and 8,000 ppm; respectively, for 6 weeks. Supplementation of SG, MOS or PDF increased final body weight, average daily gain and tended to improve feed to gain ratio (p = 0.02, 0.04 and 0.16; respectively), other than average daily feed intake, intestinal pH and the bacterial populations were not influenced by the dietary treatments. SG significantly decreased the ammonia concentration in the caecum (p<0.05) and supplementation of SG, MOS or PDF tended to increase lactic acid and total short chain fatty acid concentration in the caecum (p = 0.08, 0.09; respectively), in addition SG, MOS or PDF slightly increased butyric acid concentration in the caecum (p = 0.14). SG highly significant increased the villous height in jejunum (p<0.01) and supplementing SG, MOS or PDF significantly increased crypt depth in jejunum (p<0.05), moreover, PDF significantly increased villous height and crypt depth ratio in jejunum (p<0.05) compared with control. The dietary treatments did not influence villous height and crypt depth in duodenum and villous height in jejunum (p>0.05). It can be concluded that supplementing SG, MOS or PDF as a feed additive has the potential to improve the growth performance, the intestinal lactic acid bacteria population, intestinal short-chain fatty acid concentration and the intestinal morphology of pigs.