Effects of dietary copper concentration and source on efficacy of phytase, phytate-phosphorus utilization, and intestinal microbiota in the chicken (<i>Gallus domesticus</i>)
High levels of dietary copper (Cu), up to 250 ppm, are normally added to poultry diets in the USA as a growth promoter and antimicrobial. However, reports of growth benefits of Cu on birds are not consistent and bactericidal/bacteriostatic effects and growth stimulation mechanisms are poorly understood. In addition, high levels of dietary Cu may affect the efficacy of phytase due to its high affinity for phytate. In the first study, effects of Cu concentration and source on in vitro phytate-P (PP) hydrolysis by phytase were investigated. Copper concentration, Cu source, and pH influenced PP hydrolysis by phytase in vitro and were related to the amount of soluble Cu and formation of insoluble Cu-phyate complex. Effects of dietary Cu addition at 250 ppm and source on digesta pH, and size of Ca, Zn and Cu complexes in intestinal digesta of broiler chickens were investigated in the second study. Copper supplementation and Cu source had no effects on pH of gizzard or duodenum+jejunum contents, however, Cu supplementation increased the pH of ileal contents (P < 0.05). Copper addition had no effects on Cu or Ca portions among soluble complexes of different molecular weight (MW) sizes but increased (P < 0.05) the percentage of Zn associated with large complexes (> 100,000 MW) by 46.08 to 59.56% and decreased (P < 0.05) the percentage of Zn associated with small complexes (< 5,000 MW) by 14.48 to 16.78%. Influence of dietary Cu concentration and source on intestinal microorganisms in vitro and in broiler chickens was studied in the third study. Lactobacilli showed quadratic increases to graded levels of Cu up to 125 ppm from Cu Sul, and E. coli showed quadratic decreases up to 250 ppm Cu from Cu Sul (P < 0.05). Addition of 187.5 ppm Cu from either Cu Sul or tri-basic Cu chloride (TBCC) had no effects on number of ileal Lactobacilli in broiler chickens. Supplementation with TBCC reduced coefficient similarity of the microbiota in ileal contents, whereas Cu Sul and TBCC had no effects on microbiota similarity coefficients or number of predominant species associated with the ileal mucosa.
0476: Animal diseases