Effect of probiotic (Saccharomyces cerevisiae) on performance of broiler chicks

One hundred, one-day-old male broiler chicks (Faobrow CD), were randomly assigned to 5 treatments (20 birds/treatment). Treatment groups were; Control diet without yeast addition (treatment 1), baker yeast 0.5% (treatment 2), baker yeast 1% (treatment 3), baker yeast 1.5% (treatment 4), baker yeast 2 % (treatment 5). Chicks were reared for 21 days. Body weight, feed consumption and feed conversion were weekly determined. All chicks were scarified at the end of 21 days and blood samples were taken from brachial vein for blood analysis, including total RBCS, hemoglobin, Packed cell volume, total white blood cells, differential leukocyte count. Serum samples were taken and assayed for estimation of total protein, triglycerides, cholesterol, calcium, uric acid, glucose, ALT and AST enzymes. Chicks in all treatments were killed at the end of the experiment by cervical dislocation, and liver, gizzard, heart, spleen, proventriculus, bursa of Fabricius, pancreas and kidney were collected, weighed, and calculated as a percentage of body weight. Body weight gain for the entire period (3 weeks) were significantly (P<0.05) increased in the treatments 3, 4 and 5, when yeast was added at a rate of 1, 1.5 and 2%, compared with the other treatments (1 and 2). These birds also had a significantly (P<0.05) higher feed intake and feed conversion ratio than others. There was no significant difference in the relative organs weights in all treatment groups. No significant changes in hematological parameters, except in hemoglobin improvement at the highest Sc inclusion rate of 2%. No differences were recorded in the percentages and absolute numbers of different WBCs in all treatment groups. Addition of yeast at a rate of 1, 1.5 and 2 %, were significantly (P<0.05) increase levels of total serum protein and glucose, compared with other treatments. All yeast additive levels were responsible for significant (P<0.05) reduction in serum triglycerides, but only at highest level (2%) for serum cholesterol, compared with other treatments. No effect on serum calcium and uric acid levels, and ALT, AST serum activities, were observed by the addition of all Sc additives levels, compared with control treatment.