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).

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This study was conducted to evaluate the e ects of adding methionine (Met) to low-protein diets and subsequent re-feeding on the growth performance, serum lipid profile, body composition and carcass quality in male broiler chicks during days of age. During the starter-grower period (days of age),

The objective of this study was to determine the effect of protein levels on production performance, immune response, liver triglyceride and plasma amino acids profile of laying hens during 21-48 weeks of age. Two groups of commercial hens (Babcock B-308) were fed with diets with different crude protein levels (14% and 18% CP). The high protein diet (18% CP) significantly increased production performance, essential amino acid intake, spleen weight (% of body weight), ND-titre (haemagglutination-inhibition test), serum albumin (g/dl), serum alpha-globulin and plasma essential amino acids (except histidine) and decreased liver triglyceride (mg/g liver) in relation to the low protein diet (14% CP). In long-term effect, therefore, this study suggested that adequate dietary condition of amino acids, particularly methionine and branch-chain amino acids is necessary for sustaining normal immunocompetence and achieving maximum production performance.

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