Effect Of Dietary Iron Supplemental Level On Growth Performance,Antioxidant And Intestinal Barrier Of Yellow Broilers

This study was conducted to investigate the dose effect of iron on growth performance,antioxidant capacity and intestinal barrier in yellow broilers to provide scientific base for iron supplementation in the diet of yellow broilers.A total of 720 1-day-old yellow male broilers were allocated into 9 treatments with8 replicate cages of 10 birds per cage.Dietary iron supplemental levels of each group were 0,20,40,60,80,160,320,640 and 1280 mg/kg,respectively.The experimental period was 63 days,which was divided into three stages: 1-21 days old,22-42 days old and 43-63 days old.The main results were as follows:(1)The average daily gain(ADG)and average daily feed intake(ADFI)of yellow broilers at all stages were linearly decreased with dietary iron supplemental level increasing(P<0.05).However,compared with the birds in control group,birds fed with20 mg Fe/kg had higher ADG at 1 to 21 days of age(P<0.001).The abdominal fat percentage showed a linear decreased with increasing dietary iron supplemental levels of yellow broilers at 63 days of age(P<0.001).(2)The malondialdehyde(MDA)content in plasma,liver,duodenum and jejunum mucosa showed a linear decreased with increasing dietary iron supplemental levels of yellow broilers at 21 and 63 days of age(P<0.05).(3)The secretory immunoglobulin A(s Ig A)concentration in jejunum mucosa showed a quadratic increased with increasing dietary iron supplemental levels at 21 days of age(P=0.031).Compared with the birds in control group,birds fed with 80mg/kg iron had higher s Ig A concentration in jejunum mucosa at 21 days of age(P=0.028).The s Ig A concentration in jejunum mucosa showed a linear decrease with increasing dietary iron supplemental levels at 63 days of age(P<0.001).(4)The iron concentation in liver and duodenum mucosa showed a linear increased with increasing dietary iron supplemental levels at 21 and 63 days of age(P<0.001).The copper and manganese concentration in duodenum mucosa were linearly decreased with dietary iron supplemental level increasing at 21 and 63 days of age(P<0.05).Correlation analysis revealed a significant negative correlation between duodenum mucosa iron and copper concentration,and iron and manganese concentration(P<0.05).(5)The duodenum villus height and ratio of villus height to crypt depth,jejunum villus height at 21 and 63 days of age and jejunum ratio of villus height to crypt depth at 63 days of age were linearly decreased with dietary iron level increasing(P<0.05).The crypt depth in duodenum showed a linear increased with increasing dietary iron supplemental levels at 63 days of age(P=0.003).The divalent metal transporter 1(DMT1)and ferroportin 1(FPN1)m RNA expression levels in duodenum mucosa showed a linear decreased with increasing dietary iron supplemental levels at 21 and63 days of age(P<0.001).The zonula occludens 1(ZO-1),Occludin and Claudin-1m RNA expression levels in jejunum mucosa showed a linear decreased with increasing dietary iron supplemental levels at 21 and 63 days of age(P<0.05).The Ace and Chao index in cecal microflora at 21 days of age were affected by dietary iron supplemental group(P<0.05).Compared with the control group,20 and 1280 mg/kg supplemental iron significantly increased the Ace and Chao index(P<0.05).Compared with the control group,the 1280 mg/kg iron supplementation significantly decreased the Shuttleworthia in cecum at 21 days of age(P=0.015).In conclusion,20 mg/kg of Fe supplementation in yellow broiler basal diets containing 79.6 mg Fe/kg improved growth performance on d 1 to 21.However,when the iron supplemental levels were increased to 320 mg/kg or above,oxidative stress,the loss of morphology and barrier function of intestinal mucosa were observed.When the iron supplemental levels were further increased to 1280 mg/kg,growth performance was negatively affected.