Effect of Protein and Energy Intake on Lamb Production and Certain Blood Constituents of Ewes

Abstract

Eighty ewes and 87 lambs were used to evaluate the adequacy of varying levels of energy and protein in the rations of gestating and lactating ewes. The levels of digestible protein (DP) and total digestible nutrients (TDN) required by ewes weighing 130 to 140 lb. for optimum production during early gestation, late gestation and early lactation were approximately 0.18 and 1.7; 0.22 and 2.4; and 0.29 and 2.8 lb. of DP and TDN, respectively, per ewe per day. Digestion trials were conducted with the ewes receiving each ration in order to establish TDN and DP intake. The level of total plasma proteins was lowered by decreasing the protein content of the ration or raised by increasing protein intake. These changes were almost entirely due to changes in the level of albumins present. The ration fed did not change the globulin level of the blood. Globulin level was dependent upon stage of pregnancy, with the peak being reached 4 to 6 weeks prior to the lowest level which occurred near parturition. Non-protein nitrogen level seemed to be affected by both level of feeding and stage of reproduction. The energy content of the ration appeared to directly affect blood glucose level; there was an indication that both energy and protein content may influence the level of this constituent. The blood lipid level in all lots reached a peak near parturition and declined during lactation.