Influence of dietary inorganic and organic copper salt and level of soybean oil on plasma lipids, metabolites and mineral balance of broiler chickens

Abstract

An experiment was conducted to determine the influence of dietary inorganic (copper sulphate) and organic (copper proteinate) form of copper salt and level of soybean oil on plasma lipids, metabolites and mineral balance of broiler chickens. Two hundred-day-old commercial Vencobb broiler chicks were purchased and randomly distributed to 20 cages of 10 birds each. These replicates were randomly assigned to one of five treatments in a {(2 × 2) + 1} factorial arrangement. Factors were sources of Cu-salt (Cu-sulphate versus Cu-proteinate) fed at two dietary level (200 mg and 400 mg/kg dietary DM) and the control (no supplemental Cu). After the starter period (up to 3 weeks), from day 22 onwards another factor, i.e. levels of soybean oil (0 and 40 g/kg diet) was introduced with the previous factorial arrangements by subdividing each replicate with two equal parts. Chicks were housed in a battery type California cages. The birds were given a diet based on maize and soybean meal during starter and finisher period and the Cu content of the basal diet was 10.5 and 10.8 mg/kg diet, respectively. Two birds from each replicate were slaughtered on days 21 and 42 and blood samples were collected for analyses of plasma lipid and biochemical profiles. Two metabolism trial of 3 days duration were conducted after days 18 and 39 of feeding trial to determine mineral balance of broiler chicken. Cu-P supplementation decreased (P<0.01) plasma cholesterol, LDL-C, phospholipids, triglyceride and blood GSH in comparison to CuSO 4 at both days 21 and 42 but increased HDL-C (P<0.01) at day 21. Dose of Cu supplementation showed a linear response (P<0.01) for all the parameters studied under lipid profiles except total lipids and VLDL-C at both days 21 and 42. Supplementation of SBO in the diet decreased (P<0.01) cholesterol, HDL-C, triglyceride and VLDL-C; but increased (P<0.01) phospholipids and blood GSH. Concentration of plasma glucose, proteins, enzymes and major minerals were similar among the treatments at both starter and finisher period. Concentration of haemoglobin, packed cell volume, total erythrocyte count and major mineral balance were not affected by dose and source of Cu-salt at day 21 and by oil, dose and source of Cu-salt at day 42. Dose of Cu-salt linearly increased (P<0.05) plasma Cu and decreased (P<0.05) plasma Zn level but did not alter (P>0.10) other plasma trace minerals like Mn and Fe both at days 21 and 42. Supplementation of Cu-P showed higher (P<0.05) concentration of plasma Cu both at starter and finisher period. SBO was not found to alter (P>0.10) plasma major and trace mineral concentration at finisher period. Birds fed diet supplemented with Cu-P linearly increased (P<0.01) retained Cu and decreased Zn metabolizability compared to inorganic Cu, i.e. CuSO 4. The rate of reduction in retained Zn by Cu was more in CuSO 4 than Cu-P. Effect of addition of SBO reduced (P<0.01) metabolizability and retained (mg/day; P<0.05) Cu and Zn. Cu-P supplemented birds showed higher (P<0.01) body weight and carcass weight compared to CuSO 4 supplementation. Proportion of abdominal fat was decreased (P<0.01) with the increased dose of Cu irrespective of Cu-salt at both days 21 and 42 and by the addition of oil (P<0.05) at day 42. In conclusion, Cu-P supplemented birds showed a reduction of plasma cholesterol, compared to CuSO 4 supplementation. An added level of 400 mg Cu/kg DM was not toxic to the birds during the feeding trail. Dose and source of Cu had an important role in the plasma lipids and mineral balance in commercial broiler birds even in presence of soybean oil.