Effect of replacing inorganic zinc supplements with organically chelated zinc supplements on ewe and lamb performance
Take Home Message: Replacing inorganic zinc supplements with organically chelated zinc supplements has no effect on ewe or lamb performance, but hoof hardness is increased at lambing.
Dietary Zn supplements for ruminants have traditionally been inorganic salts, such as zinc oxide (ZnO) or zinc sulphate (ZnSO4). Studies in dairy cows and in sheep have demonstrated a beneficial effect of replacing inorganic Zn supplements with an organic source of Zn on performance and udder health. “So it is possible that supplementing ruminant diets with organic sources of Zn at high concentrations has a beneficial effect on performance,” Harper Adams’ Madeleine Cave told delegate at this year’s British Society of Animal Science’s annual conference.
“The aim of our two studies was to investigate the effects of replacing ZnO with Bioplex® Zn on performance of pregnant ewes and their lambs,” explained Miss Cave.
Twin-bearing Suffolk cross North Country mule ewes (33 in experiment one and 48 in experiment two) were individually penned from six weeks pre-partum to four weeks post-partum and fed an isonitrogenous, isoenergetic concentrate diet containing one of three treatments: control (no supplemental Zn); ZnO (an additional 50 mg Zn/kg DM as ZnO); or Bioplex® Zn (an additional 50mg Zn/kg DM as Bioplex Zn).
In experiment one the basal diet contained 81mg Zn/kgDM and in experiment two it contained 46mg Zn/kg DM. At four weeks of age lambs were offered ad lib. creep, which was an isonitrogenous, isoenergetic, high fibre concentrate feed. Lambs were weaned at eight weeks of age.
In experiment one, the creep, which contained a basal level of 140 mg Zn/kg DM, contained no supplemental Zn. In experiment two, creep contained the same level and source of supplemental Zn as fed to the dam, with a basal level of 52 mg Zn/kg DM.
In experiment two, one lamb from each ewe was individually penned at weaning until 15 weeks of age and given ad lib. creep containing the same level and source of supplementary Zn as the dam. Ewes and lambs were weighed on a weekly basis in both experiments.
In the second experiment, ewe hoof hardness was measured at lambing and the results were analysed.
“There were no significant effects of supplementing the control diet with 50mg Zn/kg DM on ewe live weight change, lamb birth weight, weaning weight or growth rate, regardless of zinc source,” said Miss Cave. “And in the second experiment, hoof hardness at lambing was significantly greater in ewes receiving the Bioplex® zinc diet compared to those fed either the control or ZnO diets.”
Full details: Cave MK, Mackenzie Am, Wilkinson RG and Sinclair LA: “The effect of replacing traditional inorganic zinc supplements with organically chelated zinc supplements (Bioplex® Zn) on performance in sheep.”
Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.
To view proceedings of all summaries presented at the Annual Conference http://www.bsas.org.uk/Publications/Annual_Conference_Proceedings/ To view all Powerpoint presentations http://www.bsas.org.uk/Members_Area/
For further information contact: BSAS on 0131 650 8784 or bsas@sac.ac.uk
