The Effect of Growth Rate on Copper Requirements of Growing Lambs

Abstract

Magagi, LB. and Kincaid, R.L. 1995. The effect of growth rate on copper requirements of growing lambs. J. Appl. Anim. Res., 8: 1–12.

An experiment was conducted to determine the effects and interactions of dietary energy and Cu on measures of nutritional Cu status in growing lambs. The hypothesis was that dietary Cu requirements are affected by growth rate and caloric intake: In a 2 x 2 factorial design, 16 weanling lambs (ave. BW=22 kg) were assigned to dietary treatments of: 1) low energy (LE), low Cu; 2) LE, high Cu; 3) high energy (HE), low Cu; and 4) HE, high Cu. The low and high Cu diets were formulated to contain 8 and 16 ppm; and the low and high energy diets were formulated to contain 2.1 and 2.5 Meal NE/kg, respectively. The diets were fed for 16 wk and the lambs were slaughtered. Lambs fed the HE diets had higher average daily gain (ADG, 152 vs. 59 g/d, P<0.05) and higher dry matter intake (DMI). Concentrations of Cu in liver were increased (P<0.05) by high dietary Cu (390 vs 173 μg/g, DM) but not affected by dietary energy. Concentrations of Cu in kidney and serum were not affected by dietary treatments. However, concentrations of Cu in bone were decreased and serum ceruloplasmin increased by high dietary energy. In this trial, no effect of growth rate on the Cu requirement of lambs was observed. The results indicate the Cu requirement of growing lambs is not affected by caloric intake and growth rate, but an interaction of dietary energy and Cu metabolism was shown for ceruloplasmin (Cp) and bone Cu.

Key words:

• Copper
• Energy
• Lambs
• Growth
• Requirements