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| Two experiments were carried out to investigate the effects of bioefficacy of DL-2-Hydroxy-4-Methylthio-Butanoic Acid (HMTBA) for layers fed on medium or low nutrient level diets under restricted feeding (Exp.1) or ad libitum feeding (Exp.2) on egg production and quality. In Exp.1, a total of 2000 layers were assigned to 10 treatments in a completely randomized design, with 10 replicates per treatment, whilst in Exp.2 there were 10 replicates (15 hens per replicate) of 10 treatments. In all experiments, the bioefficacy of HMTBA was set at 80%, 84%, and 88% (on weight basis). In Exp.1, Methionine deficiency significantly (P < 0.05) reduced egg weight and eggshell weight regardless of the dietary nutrient level. Bioefficacy of HMTBA had no influence (P > 0.05) on any egg production or egg quality parameters of hens when compared with DL-methionine (DLM) treatments. In Exp.2, egg production, ADFI, egg weight, egg mass and feed conversion ratio significantly declined due to methionine deficiency (P < 0.01). There was no difference (P > 0.05) between HMTBA and DLM on egg production and egg quality parameters within each dietary nutrient level. In conclusion, bioefficacy of HMTBA can be set at 88% on weight basis regardless of dietary nutrient level. |
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| Keywords:laying hens, methionine, methionine hydroxyl analogue, egg quality |
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