Effects Of Vitamin A Level On Performance, Egg Quality And Vitamin A Reserve Of Laying Hens

This experiment aimed at investigating the effects of different levels vitamin A on performance, egg quality and vitamin A levels of Hy-Line brown laying hens in Winter.This experiment used Single factor experimental design,experimental diets was divided into five groups, the add amount of control group was 8100IU/kg which was based on NY/T33-2004. The add amount of experimental group were 10500, 13200, 15600 and18000IU/kg. This study selected 525 Hy-line variety brown aying hens, layers were randomly allocated into 5 treatments with 5 replicates in a complete randomized design. The experiment comprised of 6 weeks of measurement period. During the whole period, performance was recorded carefully. At the end of experiment, five layers from every replicate which was close to treatment average weight chosen to slaughter. Blood, liver were used to measure vitamin A levels.The results showed: Add 8100~18000IU/kg of vitamin A in the diet of laying hens,compared with the control group which add 8100IU/kg of vitamin A, layers dietary vitamin A dosage 10500~18000IU/kg had similar feed intake(P>0.05), however, these experimental group significantly increased the egg amount of laying hens(P<0.05),When the amount of vitamin A added to 10500~18000IU/kg, compared with the control group, laying hens on egg weight and egg breakage rate had no significant effect(P> 0.05). In terms of egg quality,Dietary with 10500IU/kg of vitamin A significantly improved egg eggshell hardness, but no significant impact on the nutritional content of other conventional eggs and egg quality indicators. Compared with the control, laying hens diets vitamin A added level reached18000IU/kg, the hens significantly increased(P<0.05) the content of serum and liver vitamin A. Compared to the control, dietary 10500~18000IU/kg of vitamin A significantly(P<0.05)increased in vitamin A content of eggs, the group with15600 IU /kg was the best in improving the vitamin A content on eggsThese results suggest that adding 10500~18000IU/kg of vitamin A can significantly improve egg amount, raise eggshell hardness, and increase the content of vitamin A on serum,liver and eggs. Considered from the production performance and egg quality, the laying hens diets vitamin A suitable dosage is 10500IU/kg; from the perspective of the body vitamin A content, laying hens dietary vitamin A suitable dosage is 15600IU/kg.