The net iron, manganese, copper, and zinc requirements for maintenance and growth of Dorper × Hu ewe lambs

Abstract

A comparative slaughter trial was conducted to estimate the net trace element requirements of Dorper × Hu ewe lambs. Thirty-five ewe lambs with an initial body weight of 33.52 ± 0.56 kg, were used. Seven ewe lambs were randomly chosen and slaughtered at 34.85 ± 0.37 kg body weight as the baseline group for measuring initial body composition. Another seven lambs were also randomly chosen and offered a pelleted mixed diet for ad libitum intake and slaughtered at 41.47 ± 0.53 kg body weight. The remaining ewe lambs (n = 21) were allocated randomly on d 0–3 treatment intake levels within seven slaughter groups. A slaughter group contained 1 lamb from each treatment, and lambs were slaughtered when the ad libitum treatment lamb reached approximately 50 kg body weight. The daily net trace element requirements for maintenance were 310.4 µg Fe, 4.4 µg Mn, 35.7 µg Cu, and 110.3μg Zn/kg of empty body weight. The net trace element requirements for growth decreased from 41.02 to 37.05 mg Fe, 0.52–0.49 mg Mn, and 3.39–3.10 mg Cu and increased from 34.21 to 35.80 mg Zn/kg empty body weight gain (EBWG) from 35 to 50 kg body weight. The net Fe, Mn, Cu and Zn requirements of Dorper × Hu ewe lambs for maintenance were greater than the recommendations of the NRC, and the net Fe and Mn requirements of Dorper × Hu ewe lambs for growth were lower than the recommendations of the NRC, except that the net Cu and Zn growth requirements were greater than the recommendations of the NRC.