In the latest issue of Journal of Applied Poultry Research, M.A. Brooks and colleagues at North Carolina State University report their experiment, which aimed to evaluate the relative bioavailability of zinc from zinc propionate relative to feed-grade zinc sulphate using bodyweight gain and bone zinc as response criteria.

For the first seven days post-hatching, chicks were fed a semi-purified starter diet deficient in zinc (22mg zinc per kg). From days 8 to 21, birds were fed a control (20mg zinc per kg) semi-purified diet containing ground maize, soy protein concentrate and dextrose. The control diet was supplemented with 0, 6 or 12mg zinc per kg of diet from feed-grade zinc sulphate or organic zinc propionate.

Using maize in the diet increased the level of phytate, an important zinc antagonist in non-ruminant animals.

As supplemental dietary zinc increased, a dose-dependent increase was observed in feed intake, weight gain, total zinc intake, tibia zinc concentration and total tibia zinc.

Zinc supplementation improved feed efficiency (feed:gain) but not in a dose-dependent manner. Relative bioavailability of zinc was determined using weight gain, tibia zinc concentration and total tibia zinc, assuming a value of 100 per cent for feed-grade zinc sulphate. Using relative slope assay, relative bioavailability of zinc propionate was 119, 116 and 116 per cent compared with zinc sulphate, respectively.

Based on these results, Brooks and colleagues concluded that the bioavailability of zinc from organic zinc propionate is greater than feed-grade zinc sulphate in the presence of dietary phytate.

Reference

^{Brooks M.A., J.L. Grimes, K.E. Lloyd, S. Verissimo and J.W. Spears. 2013. Bioavailability in chicks of zinc from zinc propionate. J. Appl. Poult. Res. 22(2):153-159. doi: 10.3382/japr.2012-00525}

June 2013