Thirty-two 3-4 months old upgraded goats (Native X Anglo Nubian) with mean body weight of 13.6 kg were used to determine the effects of concentrate supplementation on plasma contents of calcium (Ca), magnesium (Mg), phosphorous (P), sulfur (S), copper (Cu) and zinc (Zn), as well as the growth performance of goats under intensive system of operation. Aside from the forage diet, about 160-200 g/day of concentrate feeds were given to 20 of the animals (treated group) while the remaining 12 animals (control) were fed with roughage alone. Bi-weekly blood sampling and body weight measurements were taken, and plasma concentrations of Ca, Mg, P, S, Cu and Zn were analyzed using Inductively Coupled Plasma Emission Spectrophotometer (ICPS).
The beneficial effects of concentrate feeding on the mineral status of growing goats were observed only in P and Zn, elements involved in energy metabolism. The addition of concentrates to forage diet resulted in higher plasma contents of P (P<0.05) and Zn (P<0.01) of growing upgraded goats as compared to that of those fed with forage diet alone. The higher contents of P and Zn in the plasma of growing goats fed with supplementation, were accompanied by a threefold increase (P<0.01) in their live weight and average daily gain (ADG) compared to those in the control group. This Significant difference in performance between treated animals and the control group occurred two months after concentrate feeding until the end of the feeding trial. This may suggest that the positive effects of concentrate feeding could be manifested by higher blood concentrations of mineral elements involved in energy metabolism.
All growing upgraded goats did not show any clinical or sub-clinical signs of Ca, P, Mg, S, Cu, and Zn deficiency during the 5 months feeding trial. All plasma mineral contents were within the normal range and above the critical levels for specific elements under study. None of the animals in the control group showed signs of any mineral deficiency symptoms. This indicates that Ca, P, Mg, S, Cu, and Zn from the forage diet alone were adequate to support the requirement of growing upgraded goats under intensive system of management.