The effects of different dietary amounts of organic and inorganic Zn were studied in male White Pekin ducks (WPD) from 1 to\ud56 days of age. The control diet (26 ppm of Zn from raw ingredients) was supplemented with 30, 60 and 120 ppm of Zn from both\udinorganic and organic sources, for a total of seven treatment groups, each containing five replicates of nine 1-day-old ducklings\udeach. BW, feed intake and feed conversion ratio (FCR) were recorded at 1, 28 and 56 days of age. At 56 days of age, five birds\udper group were used in a digestibility trial to measure Zn retention and excretion. At the end of the trial, five birds per treatment\udwere slaughtered and carcass traits as well as Zn content in tibia and liver were measured. Samples of blood from five birds per\udtreatment were used to measure plasma concentration of Zn and Cu. BW gain during the entire period of the trial increased\ud( P,0.001) by 30 and 60 ppm of Zn. Increasing Zn contents progressively increased ( P,0.001) the tibia and the liver Zn contents\udas well as the plasma Zn and Cu contents. The concentration of 120 ppm of Zn increased ( P,0.001) tibia ash and decreased\ud( P,0.001) abdominal fat in the carcasses. In the period 1 to 56 days, Zn oxide increased ( P,0.001) growth rate and improved\ud( P,0.03) FCR compared with organic Zn, whereas organic Zn increased ( P,0.003) the dressed carcass percentage. Organic Zinc\udincreased ( P,0.001) Zn and Cu concentration in the plasma. A level of 30 ppm of Zn from an inorganic source was adequate for\udmale WPD during 1 to 56 days of age, based on positive effects of growth rate and Zn excretion.
展开▼
