Animal and human food safety of chromium propionate in layer hen diets

The objective of this study was to determine the animal and human food safety of KemTRACE® chromium propionate (Cr Prop) when supplemented to layer diets at 1 and 5 times the recommended level. Three-hundred 21-wk-old Hy-Line W-36 layer hens were randomly assigned to treatments consisting of: Cr Prop supplemented to provide 0, 0.20, or 1.0 mg Cr/kg diet. The study was conducted from 21 through 36 wk of age. Eggs were collected during wk 24, 28, 32, and 36 for egg quality measurements. Eggs were collected on d 0, 28, 56, 84, and 112 for Cr analysis. At the end of the study blood was collected from the wing vein for plasma biochemical measurements and samples of liver, breast muscle, kidney, and skin (with adhering fat) were then obtained for Cr analysis. In wk 21-24 ADFI and egg production were lower (P = 0.01) in hens receiving 1.0 mg Cr/kg compared to the other treatments. Egg production was not affected by treatment from wk 25 - 36. This suggests an adaptation to the high level of Cr over time. Over the entire 16-wk study, ADFI was greater (P = 0.01) for hens receiving 0.20 or 1.0 mg Cr/kg diet than controls and egg production was lower (P = 0.01) for hens supplemented with 1.0 mg Cr/kg compared with those in other treatments. Egg yolk color was lower (P = 0.03) for hens receiving 1.0 mg Cr. Other egg quality measurements were not affected by treatment. Hens supplemented with 0.20 mg Cr/kg had lower (P ˂ 0.05) plasma cholesterol, chloride, lipemic index, and bile acid concentrations than controls. Supplementation of 1.0 mg Cr/kg increased (P ˂ 0.05) liver Cr relative to the control treatment, but did not affect Cr concentrations in eggs, breast muscle, kidney, or skin with adhering fat. Tissue Cr concentrations were similar in hens receiving 0 or 0.20 mg Cr/kg. Results support the human food and animal safety of Cr Prop supplemention to layer diets for up to 16 wk.