A comparison of the copper status of sheep and cattle grazing a predominantly Paspalum dilatatum pasture in south-eastern Queensland

Abstract

A study was made, over a period of three years, to compare the liver and blood copper concentrations of adult Hereford cattle with those of adult Merino sheep simultaneously grazing the same predominantly Paspalum dilatatum pastures. Blood and liver samples were taken on 15 occasions during this period.
Mean liver copper levels in cattle were less than 30 p.p.m. (D.M.) at all except one sampling, when 34.5 p.p.m. (D.M.) was recorded. Levels in sheep were greater than 100 .p.p.m. for 12 of the 15 samplings. Mean blood copper levels in cattle were less than 0.08 mg/100 ml on 13 occasions, and on only 3 occasions for sheep. There was no consistent seasonal pattern in the changes in copper concentrations in liver and blood of either cattle or sheep.
Comparisons in two successive years indicated that pregnancy did not influence liver or blood copper concentrations in sheep.
Liver copper concentrations were determined in calves and lambs and their dams within 24 hr of parturition. In both cattle and sheep, liver copper concentrations in the new-born were significantly higher than in their dams. Cows with mean liver copper concentrations of 17.1 p.p.m. (D.M.) in 1957 and 9.8 p.p.m. (D.M.) in 1958 gave birth to calves with mean liver copper levels of 361 and 329 p.p.m. (D.M.) respectively. In 1957, ewes with mean liver copper levels of 103 p.p.m. (D.M.) produced Iambs with mean liver copper levels of 157 p.p.m. (D.M.). In 1958, ewes giving birth to single lambs had mean liver copper levels of 134 p.p.m. (D.M.) and the levels in their lambs were 239 p.p.m. (D.M.). In the same year, the six ewes with twin or triplet lambs had liver copper levels of 141 p.p.m. (D.M.) and their lambs averaged 262 p.p.m. (D.M.).
The high liver copper concentrations in new-born calves declined rapidly in both the years studied. The rate of decline appeared to be more rapid in the year that calves grew at a faster rate. There was little decline in liver copper concentration in the growing lambs in 1957. In the next year, lambs had higher liver copper concentrations at birth, but these declined during the first four months to approximately 47 per cent. of the initial values.