Determination of copper status of grazing sheep: seasonal influence.

Abstract

A study was conducted to determine the copper status of different classes of grazing sheep during two different seasons on a farm located in southern Punjab, Pakistan. A complete free-choice supplement was available to all animals throughout the year. Soil, forage and blood plasma from animals were taken eight times during the year (2005) (four times in both summer and winter seasons). Soil Cu was affected by the seasonal changes (P 0.05) fluctuation in winter. It was adequate for ruminants’ requirements during both seasons. plasma Cu concentrations of all classes of sheep were significantly higher in winter than that in summer showing the seasonal changes (P<0.001). Higher plasma Cu was found in male sheep than lactating and non-lactating sheep during both seasons. The low Cu in plasma in lactating sheep may have been due to its secretion in milk. In winter forage Cu contributed in enhancing the plasma Cu levels, but in summer the forage Cu level, although very high, was ineffective in elevating plasma Cu levels in all classes of sheep. Based primarily on plasma analyses it was concluded that although, the adequate level of plasma Cu was found, it was on borderline deficient levels. Thus supplementation is needed with mixture containing Cu. The plus copper should be continuously supplemented to grazing animals in this semiarid region of Pakistan.