Effects Of Different Sources Of Dietary Chromium On Meat Quality Of Broilers

An experiment was conducted to evaluate the effects of different sources of dietary chromium on growth, meat quality and the digestion and absorption of trace elements in broilers. Seven hundred and ninety-two one-day-old Arbor Acres broilers were randomly allocated to six dietary treatments (four replicates of thirty three broilers per replicate, respectively). The dietary treatments were:1) corn-soybean meal basal (B; according to NRC,1994),2) B+0.2mg·kg-1of Cr (as Yeast chromium),3) B+0.2mg·kg-1of Cr (as Chromium picolinate),4) B+0.1mg·kg-1(as Methionine chromium; Ⅰ),5) B+0.2mg·kg-1(as Methionine chromium; Ⅱ),6) B+0.6mg·kg-1of Cr (as Methionine chromium;、).Broilers were given a free choice access to diets and tap water for49d. The results showed as follow,1) Compared to the control group, average daily feed intake (ADFI) was reduced (P<0.05) in broilers fed diets with different sources of dietary chromium, average daily gain (ADG) and survival rate were not affected (P>0.05) by treatments. Feed conversion ratio was increased (P<0.05) in broilers fed diets with yeast chromium, the average daily gain was decreased in the chromium picolinate group (P<0.05). Heart relative weight was decreased (P<0.05) in broilers fed different sources of dietary chromium, other viscera relative weight were not affected (P>0.05) by diets. Blood biochemical indicator ALB, TC, TP. GLU were increased (P<0.05) in broilers fed diets with methionine chromium and chromium picolinate. Serum HDL-C and LDL-C were increased by methionine chromium (Ⅱ) and (Ⅲ). There were no significant differences within methionine chromium groups about the blood biochemical indicator.2) Compared to the control group, fiber density of breast muscle was reduced (P<0.05) in broilers fed yeast chromium, methionine chromium(Ⅱ) and (Ⅲ) diets. Fiber areas of leg muscle was reduced (P<0.05) in broilers fed yeast chromium and chromium (Ⅲ) diets. Total antioxidant capacity (T-AOC) of leg muscle was increased (P<0.05) in broilers fed methionine chromium(Ⅱ), total antioxidant capacity (T-AOC) of breast muscle and catalase(CAT) of leg muscle was increased (P<0.05) in broilers fed methionine chromium(Ⅲ). Malondialdehyde (MDA) of breast muscle and leg muscle were not affected (P>0.05) by treatments. Main amino acids of muscle were not affected (P>0.05) by treatments, with the exception that broilers fed chromium picolinate had a reduced (P<0.05) in alanine of breast muscle.3) Compared to control group, dietary copper was significantly decreased in the yeast chromium and chromium picolinate groups (P<0.05), dietary zinc was significantly decreased in the methionine chromium(Ⅱ) group (P<0.05). Fecal copper, zinc or manganese were significantly increased in chromium picolinate and Methionine Chromium (Ⅱ) groups (P<0.05), iron was not affected by treatments in diet and feces (P>0.05). The mucosal thickness of jejunum were increased, and the length of villus and mucosal thickness of ileum were decreased (P<0.05) by treatments. These results suggest that,1) with the exception that average daily feed intake and blood indexes had significant effect by diets with different chromium; growth and slaughter performance were not affected by treatments.2) Dietary supplementation of Methionine chromium in broilers had a significant effect on oxidation resistance of muscle; however, the main amino acids of muscle were not affected by treatments.3) Trace elements of copper, zinc and manganese were obvious effect by adding different sources of chromium, iron was not affected by treatments (P>0.05). Jejunum is the primary site of chromium absorption.4) The recommended dosage of methionine chromium for broilers is0.2mg·kg-1.