Effects Of Chromium Picolinate On Growth Performance, Physiological And Biochemical Indexes Of Laying Ducks

The experiment was conducted to research the effects of different chromium levels on the growth performance, physiological and biochemical indexes of caged laying ducks aged from 5~10 weeks. The appropriate level of dietary chromium was determined by quadratic regression analysis of the obvious differences index. There were 180 Jin-ding laying ducks of 28 day old, healthy with average weight close. They were divided into five groups with six replicates, and each replicate contained six ducks according to the single factor with completely random design. Corn-soybean basal diet was the basal diet of the experiment. The control group(I) was fed with basal diet and the experimental groups(II~V) were fed with corn–soybean basal diets supplemented 0.15 mg/Kg, 0.30 mg/Kg, 0.45 mg/Kg, 0.60 mg/Kg chromium, respectively, which add in the feed as chromium picolinate. The test period was 6 weeks(5-10 weeks of age). Feed intake and the body weight were recorded to calculate average daily gain, average daily feed intake and feed weight ratio per two weeks during the whole experimental procedure. At the end of the experiment, one close to the average weight of the repeat was selected from each repeat to record the live weight, then blooding from the jugular vein for determination of biochemical indicators. After that, the duck was slaughtered and respectively took the thymus, spleen, bursa of fabricius and the liver out from the duck for mensuration.Results of growth experiment: average daily weight gain of 5-10 weeks cadged laying duck was significantly improved(P<0.05) while feed weight ratio and daily intake was not influenced significantly(P>0.05) when dietary chromium level was 0.30 mg/Kg. As chromium level rises, daily weight gain had a tendency that increased first and then decreased. Suitable chromium level had a certain influence on growth period of caged laying ducks. Growth performance of ducks was not good, neither too high nor too low level of chromium.Immune organ index: thymus index was significantly influenced(P<0.05), but bursa and spleen indexs were not influenced significantly(P>0.05) when dietary chromium level was 0.30 mg/Kg.Antioxidant index: The activity of total anti-oxidatiaon capability(T-AOC) in liver was significantly improved(P<0.05), but the activity of total anti-oxidatiaon capability(T-AOC) in serum was not influenced significantly(P>0.05) when the dietary chromium level was 0.30 mg/Kg. Total super-oxide dismutase(T-SOD) in liver and serum and glutathion peroxidase(GSH-Px) in serum were significantly improved(P<0.05) when dietary chromium level was 0.30 mg/Kg. The concentration of malondialdehyd(MDA) was decreased significantly in serum(P<0.05).Serum biochemical index: The concentrations of glucose(GLU), total protein(TP) and albumin(ALB) in serum were increased significantly(P<0.05), triglyceride(TG) and total cholesterol(TC) contents were decreased significantly when dietary chromium level was 0.30 mg/Kg. The concentration of ureanitrogen(BUN) in serum was influenced significantly(P<0.05), and the concentration of BUN was the lowest when dietary chromium level was 0.15 mg/Kg.Serum immune index: The concentrations of Ig G, Ig M and IL-2 were increased significantly(P<0.05), but Ig A was not influenced significantly(P<0.05) when the dietary chromium level was 0.30 mg/Kg.Serum hormone index: The concentration of GH in serum was increased significantly(P<0.05) but the concentration of Insulin was not influenced significantly(P>0.05) when dietary chromium level was 0.30 mg/Kg.According to the analysis of final test data from growth performance, immune index, antioxidant index, biochemical index and hormone index, the following conclusions showed that appropriate chromium level in corn-soybean meal basal diet improved growth performance, immune and antioxidant functions of caged laying ducks. All indexes were taken into consideration and the appropriate level of chromium(0.297 mg/Kg-0.423 mg/Kg) was determined by conic regression model.