Two experiments were conducted to determine the influence of zeolite(Z) and sodium metasilicate(S.M) in diet on performance of laying hens.The first trial was carried out on 720 commercial layers and 32-weeks old hens.They were fed three levels of zeolite and sodium metasilcate(0, 0.5 on %)in the diets containing two levels of Calcium and phosphorus 3.4 Ca,0.34 P(diet A) %and 2.7 Ca, 0.27 P(diet B) for 15 weeks. The results showed that the addition of 0.5 % zeolite in the diets A was significantly (P < 0.05) increased egg production , feed consumption and specific gravity of egg. Addition of sodium metasilicate in the diets A also significantly (P < 0.05) increased the egg production. The addition of 0.5 % was more effective than 1 % level in decreasing the specific gravity .The second trial was performed on the same 720 commercial layers 52-week old and were received three levels of zeolite and sodium metasilicate (0, 0.5 or 1 %) in diets containing two levels of Ca and P that mentioned in first experiment. The results were showed that feeding 0.5 % Zeolite in diets A significantly (P < 0.05) increased egg production ,egg weight, feed consumption, feed efficiency and specific gravity of egg.However the addition of 0.5 % zeolite in the diet B was more effective than in the diets A on egg production and feed efficiency. Addition of the 1 % zeolite in the diets was less effective than of 0.5 % of zeolite on egg production and feed efficiency. The addition of 1 % zeolite depressed specific gravity. The addition of 0.5 % and % 1 sodium metasilicate in diets A and B was significantly (P <0.05) increased the egg production and feed efficiency as well. The diets B that contained 1 % sodium metasilicate, were significantly (P < 0.05) decreased the specific gravity of the egg.
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