Effects of dietary deficiencies of energy, protein and calcium on the pregnant ewe

Abstract

Summary Scottish Blackface ewes were used to investigate the effect of protein deficiency during pregnancy on serum albumin, globulin, transferrin and plasma urea concentrations. Twenty-eight sheep were offered one of two iso-caloric diets in amounts which maintained energy intake at levels comparable to those found in hill sheep during winter. For half of the sheep (HP group) the crude-protein concentration was 11·8% and for the remainder (LP group) 6·0% in the dry matter. A further six sheep (group CL) were offered a diet containing 16·0% crude protein in amounts which prevented undernutrition. Concurrent changes in plasma volume and in certain serum proteins during pregnancy were determined in a second experiment. Serum globulins were not affected by protein intake and fell from 44·5 to 30·7 mg/ml during pregnancy. This was attributed mainly to a 30% increase in plasma volume which occurred during pregnancy. Serum albumin concentrations at the end of pregnancy were 29·3, 22·0 and 17'7 mg/ml and serum transferrin concentrations 400, 307 and 300 mg/100 ml in the CL, HP and LP groups respectively. Initial mean albumin and transferrin concentrations were 28·0 mg/ml and 383 mg/100 ml respectively. The usefulness of the parameters as indices of the protein status of pregnant ewes was discussed. Plasma urea N concentrations were related to the current protein intake of the animal. Mean values during late pregnancy were 26·0, 7'4 and 4·0 mg urea N/100 ml in the CL, HP, and LP) groups respectively. Limitations as to its usefulness were discussed.