Resumo
The present study intended to identify the effects of the Saccharomyces cerevisiae yeast on production performance and parameters related to the quality of layers' eggs. Effects of yeast on immune titers after routine vaccinations against Newcastle disease and infectious bronchitis were also studied. Fayoumi chicken (n=288) were divided in four groups (72 in each), and Black Australorp (n=288) in four groups (72 in each). Both had 12 weeks of age and were kept in 08 groups (3 replicates per treatment). Hens were fed a controlled diet along with the addition of 0.5g, 1.0 g, and 1.5 g of S. cerevisiae per kg of feed, till 25 weeks of age. Feed intake and egg production were measured on a daily basis, while body weight gain and egg weight were measured weekly. Egg quality parameters were evaluated by picking 5 eggs from every group weekly. Birds were vaccinated for Newcastle disease (ND) and infectious bronchitis (IB) at the 18th week. Subsequently, 10 days after vaccination, antibody titers were determined by Hemagglutination Inhibition and Enzyme Linked Immunosorbent Assay for both diseases. Results showed no significant effect of S. cerevisiae on layers' weight gain and feed intake. However, egg production was increased in the experimental group. Moreover, yeast supplementation impacted positively on birds' immune system. In conclusion, probiotic supplementation improved birds' egg production and immunity.(AU)