Effect of Varying the Energy Density of Protein-adequate Diets on Nutrient Metabolism, Clinical Chemistry, Immune Response and Growth of Muzaffarnagari Lambs

Effects of varied dietary energy densities on immune response and performance of Muzzafarnagari lambs were ascertained in a 180-d study. Animals (n = 24), in three groups, were fed diets providing 100% (100E), 80% (80E) or 70% (70E) of their metabolizable energy requirement. Mean nutrient digestibilities varied significantly among treatments. Nitrogen intake was lower (p<0.01) in the 70E. Nitrogen retention, was reduced (p<0.001) in 80E and 70E vs 100E. The average daily gain (p<0.001) was $47.01{\pm}4.23$, $13.54{\pm}1.72$ and $-16.67{\pm}8.24$ g for 100E, 80E and 70E, respectively. Hemoglobin concentration, haematocrit, total and differential leukocyte counts were lower (p<0.001) for 80E and 70E than for 100E with a similar trend (p<0.05) for serum glucose and total protein. Serum cortisol was reduced (p<0.001) with decreased energy availability. Antibody titre to Brucella abortus S19 showed an initial reduction in 80E and 70E vs 100E. Delayed-type hypersensitivity response was lower (p<0.001) in 80E and 70E vs 100E, accompanying a lower (p<0.001) nitric oxide production by the peripheral lymphocytes. It is concluded that the reduced dietary energy density significantly affects the growth performance and immune response of lambs.