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An in vivo experiment was conducted to determine the effect of dietary betaine supplementation (Betafin®) as a replacement for methionine on broiler performance and carcass characteristics. In a completely randomized design (CRD) with five treatments of betaine levels (at 0, 25, 50, 75, and 100% in replacement for methionine) and five replicates of 10 birds/replicate, two hundred fifty-day-old Ross broiler chicks were randomly distributed in cages and fed the experimental diets from 0 to 49 days of age. Feed and water were provided ad libitum. Feed intake and body weight were recorded weekly. At 49 days of age, one bird from each replicate was killed for comparison of carcass characteristics. Betaine replacement for methionine had no effect on feed intake and feed to gain ratio but decreased body weight gain at 0 to 3 (P<0.0465) and 0 to 7 weeks of age (P<0.01). Betaine as a replacement for methionine decreased the breast weight (P<0.025) and tended to reduce the abdominal fat pad (48.9 vs 40.4 grams , 100% methionine vs 100% betaine replacement for methionine). The present findings do not support the hypothesis that betaine can effectively replace methionine.

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The effect of different levels of betaine and tryptophan on growth and resistance to salinities in the Caspian roach was investigated. Fish (1.90 ± 0.04 g body weight) were divided into 9 groups (4 treatments groups containing betaine (0.5 and 1), tryptophan (0.25 and 0.5), betaine and tryptophan mixtures (0.25- 0.5, 0.25, -1, 0.5-0.5 and 0.5- 1), and control group). After recording the growth factors, the fish were exposed to salinities (12, 16 and 20 ppt) and clinical symptoms and mortality rate were recorded. No mortality occurred in 12 ppt salinity. At 16 ppt, the lowest mortality (16.66%) was recorded in the treatment containing 1% betaine and 0.5% tryptophan, while the highest mortalty (59.98%) occurred in the control group. At 20 ppt salinity, 100% mortality occurred within 6 hours in the control, while in the other treatments 100%-mortality occurred after 24 hours. Behavioral symptoms, such as jerky movements, ataxia, increased respiratory rate, were more prominent in higher salinities. Tryptophan did not reduce food consumption meaningfully. Increaesd food consumption as the result of betaine did not show significant  effect on the fish growth rate.

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This study was conducted to investigate the response of four barley cultivars (Reyhan03, Yousef, Afzal, and Khatam) to salinity stress at 0 (control), 100, 200 and 300 mM levels as a factorial experiment, within the randomized complete block design in three replications in a greenhouse, using the Hoagland solution. The physiological and biochemical properties including dry weight and RWC, photosynthesis pigments, K⁺/Na⁺, osmotic adjustments (soluble sugars, glycine betaine, proline), hydrogen peroxide and antioxidants enzymes (catalase and peroxidase) in root and shoot of barley cultivars were evaluated in saline and non-saline conditions. To determine the relationship between growth performance and the physiological and biochemical properties, the correlation between the properties and causality analysis was examined. Results obtained from comparing the mean among the treatment combinations showed that the salinity stress reduced the dry weight, photosynthesis pigments, and K⁺/Na⁺, while it increased the soluble sugars, glycine betaine, proline, H₂O₂, catalase and peroxidase in the root and shoot of barley cultivars. Correlation analysis indicated that potassium in the shoot had the most positive and significant correlation coefficient (r= 0.86) with the dry matter of shoot. The stepwise regression analysis showed that the root dry weight, catalase of root and shoot, H₂O₂ of shoot and K⁺/Na⁺ of shoot contributed to the performance. Causality analysis revealed that the root dry weight, K⁺/Na⁺ of shoot, and catalase of shoot were highly important as they had a direct positive and significant impacts on the performance of shoot dry matter.