Effect of excess zinc and iron on lamb carcass characteristics

Wether hoggets and ewe and wether lambs were drenched with zinc (Zn) or iron (Fe) to determine the effect of an excess of these minerals on fat quantity, and lean quality. Hoggets given Zn or Fe sulphate by intra-ruminal intubation in 2 different trials had less kidney and subcutaneous fat than controls. Zinc oxide administered to lambs by drench gun also lowered fat deposition, but it reduced slaughter and carcass weights compared to those of controls. Drenching lambs with Zn oxide lowered the amount of Fe in muscle compared to muscle from control or Fe oxide-drenched lambs. Zn or Fe oxide had no significant effect on moisture or Zn content in the longissimus muscle of lambs. In addition, shear values, colour of lean, and muscle pH were not changed. Muscle from Southdown-sired lambs contained greater amounts of Zn than that from Suffolk-sired lambs.