Responses of broiler chickens to organic copper fed in the form of copper–methionine chelate

Abstract

An experiment was conducted to determine the responses of broiler chickens to organic copper (Cu), fed in the form of copper–methionine (Cu–Met) chelate. Two hundred day-old Ross 208 broiler chicks were purchased from a commercial supplier and randomly placed into 20 cages of 10 birds each (five males and five females). Maize/soyabean-based basal diets (broiler starter and broiler finisher) were formulated and supplemented with 0 (control), 50, 100, 150 or 200 mg Cu/kg from Cu–Met chelate, an organic source of Cu. Each dietary treatment was randomly allocated to four replicate cages. Broiler starter diet was fed to chicks from week 1 through week 3 followed by feeding a finisher diet for an additional 2 weeks. Weight gain was improved by 2–4% due to supplementation of Cu–Met chelate but none of the diets showed any significant difference from the control. The birds that received Cu–Met chelate consumed more feed during weeks 1–5 in a negative quadratic fashion ( P < 0.05). Feed conversion ratios (FCR) showed negative quadratic responses during weeks 1–5 ( P < 0.05) but appeared to be improved at the highest level (200 mg/kg) although there was no statistical difference from the control. There was no effect of Cu–Met chelate on gizzard erosion. Dietary treatments showed linear increase in serum total cholesterol ( P < 0.01). There was a significant increase (40%) in serum total cholesterol at 150 mg/kg ( P < 0.05). Serum TG showed significant reductions ( P < 0.01) at both 100 and 150 mg/kg (35% and 34% reduction, respectively). The serum high-density lipoprotein (HDL) remained unaffected. There was a linear increase in the accumulation of Cu in the liver ( P < 0.01) with significant difference from the control at 200 mg/kg supplemental level ( P < 0.01). Excretion of Cu in excreta increased significantly ( P < 0.01) from the control at all dietary levels of supplementation with a peak concentration at 150 mg/kg level. Accumulation of fat in the liver increased linearly ( P < 0.05) with increasing level of Cu–Met chelate in the diet although this increase was not statistically detectable from the control at any dietary levels. However, dietary supplementation of Cu–Met chelate did not alter fat digestibility and concentration of fat in excreta. In conclusion, dietary supplementation of organic Cu in the form of Cu–Met had no significant effect on growth performance apart from linear and quadratic responses in FCR. It may alter lipid metabolism in broilers. It has a linear effect on the accumulation of Cu and fat in liver. It also increases excretion of Cu in the excreta.