Effects of Different Iodine Supplementation Levels on Growth Performance,Thyroid Development,Blood Thyroid Hormone Level and Carcass Quality of 22 to 63-day-old Yellow-feathered Broilers
The purpose of this experiment was to study the effects of different levels of dietary iodine on growth performance,thyroid index,blood thyroid hormone content and carcass quality of fast-growing yellow-feathered broilers aged between day 22 and 63.The 22-day-old and 43-day-old fast-growing yellow-feathered broilers were selected for two feeding experiments,and the duration of each experiment was 21 days.In experiment 1,a total of 1080 male yellow-feathered broilers aged day-22 were randomly divided based on similar body weight into 6 groups with 6 replicates in each group and 30 chickens in each replicate.In experiment 2,900 male yellow-feathered broilers at 43 days of age were randomly divided into 6 groups with 6 replicates each,and 25 chickens in each replicate.Group 1 was fed basic diet,while group 2-6 were supplemented with gradient levels of Ca(IO3)2 in the basal diet.Dietary iodine levels were 0.00,0.20,0.40,0.60,0.80 and 1.00 mg/kg in each group,respectively.Results showed that dietary iodine supplemental level had no significant effects on average daily gain,average daily feed intake and feed to gain ratio in broilers at 22-42 and 43-63 days of age(P>0.05).Dietary level of 0.80 mg/kg iodine significantly increased the thyroid index and plasma T4 content in broilers at 42 day of age(P<0.05),and dietary level of 0.20 mg/kg iodine significantly increased the plasma T3 content in broilers at 63 days of age(P<0.05).Iodine supplementation significantly increased breast and thigh muscle percentage of chickens(P<0.05),but had no significant effect on dressing percentage,half-eviscerated yield percentage,eviscerated yield percentage and abdominal fat percentage(P>0.05).In summary,iodine supplemental levels have no significant effect on the growth performance of yellow-feathered broilers,but supplement appropriate amount of iodine increase blood thyroid hormone level,breast and thigh muscle percentage of yellow-feathered broilers,and improve the carcass quality.Taking plasma thyroid hormone level as the evaluation index,the appropriate iodine supplemental levels of diet for 22-42 days old and 43-63 days old fast-growing yellow-feathered broilers were 0.80 mg/kg and 0.20 mg/kg,respectively.Thus,the corresponding iodine levels of diet were 0.91 mg/kg and 0.31 mg/kg,respectively.The daily requirements were 0.90 g/d and 0.24 g/d,respectively.
万方数据
维普
