Influence of Dietary Zinc Methionine Supplementation on Eggshell Quality in Laying Hens under Hot Climate Environment.

Abstract

We have examined the influence of dietary zinc-methionine (Zn-Met ; Zn 80 g/kg, Met 160 g/kg) supplementation (500 mg Zn-Met/kg diet) on eggshell quality in laying hens under hot climate environment. The experiment was started from June 15, 1995 and continued for 12 weeks. The egg production and the quality of eggshell were measured at 0, 4, 8 and 12 weeks of experiment.The average of daily maximum temperatures in the first week was 25.5°C and then increased gradually until 8 weeks of experiment (37.5°C). Thereafter it was kept for 3 weeks and then decreased toward the end of the experiment. The rate of egg production at 4 weeks of experiment was significantly lower than that at the beginning of experiment. The number of abnormal eggs changed similarly to the variation of ambient temperatures. Eggshell weight decreased significantly from 0 to 8 weeks of experiment and thereafter increased significantly. Eggshell thickness at 8 weeks of experiment was the thinnest through the experimental period. Eggshell strength decreased gradually from 4 to 8 weeks of experiment and then increased significantly. Dietary Zn-Met supplementation did not affect eggshell quality. These results suggest that poor eggshell quality under hot climate environment was not improved by dietary Zn-Met supplementation at the level tested.