Assessment of the effects of supplementing rabbit diets with a culture of Saccharomyces cerevisiae using growth performance, blood composition and clinical enzyme activities

The effects of dietary supplementation with a pure culture of Saccharomyces cerevisiae at 0.0, 1.5 and 3.0 g kg(-1) on growth performance, blood compo sition and clinical enzyme activities in serum of rabbits were studied duri ng a 56-day experiment. Rabbits fed 3.0 g kg(-1) attained the heaviest (P < 0.05) body weight, consumed the highest (P < 0.05) quantity of feed and ha d the best (P < 0.05) feed conversion. Rabbits fed 1.5 g kg(-1) yeast had h igher (P < 0.05) body weight, feed intake and feed conversion efficiency th an the unsupplemented group. The haematocrit, erythrocytes, haemoglobin, se rum albumin:globulin ratio, and erythrocytic indices in rabbits fed 3.0 g k g-l were superior (P < 0.05) to the unsupplemented group. Other haematologi cal indices were similar (P > 0.05); but differential populations of lympho cytes were fewer (P < 0.05) and monocytes and eosinophils were larger (P < 0.05) in rabbits fed the basal group. Serum Ca2+, globulin, cholesterol, as partate and alanine aminotransferases, and alkaline phosphatase were higher (P < 0.05) in the basal group than with the yeast-supplemented diets. The data obtained suggest that yeast addition significantly improved growth per formance, enhanced haematopoiesis, reduced serum cholesterol and maintained the serum enzymes at normal ranges. Furthermore, the activities of the cli nical enzymes suggested liver- and bone-specific advantages from supplement al yeast. The effects of yeast were dose-dependent, and there is a need to determine the economically optimum dietary concentration. (C) 1999 Elsevier Science B.V.