PROBIOTIC EFFECTS OF SACCHAROMYCES CEREVISIA ON LAYING CHICKEN FED PALM KERNEL CAKE-BASED DIETS.

 
The study investigated the probiotic effects of Saccharomyces cerevisiae on pullets development and hen-day egg performance of the layers. A total of 120 chicks were brooded for 4 weeks, after which 100 pullets were randomly selected and placed in 4 groups (A-D) of 25 birds each. Groups A, B and C had their feed supplemented with S. cerevisiae at graded levels of 0.6, 0.8 and 1.0 g/kg of feed respectively. Group D diet did not contain S. cerevisiae (control). The diets for all the groups contained 25% PKC and  they were isocaloric and isonitrogenous. The pullets were weighed weekly. At 9th, 15th and 40th week of age, 5 birds were randomly selected from each pen and 2 ml. of blood collected into an EDTA bottle for haematology. The blood sample was used to determine packed cell volume (PCV), haemoglobin concentration (HbC), total leukocyte count (TLC) and differential leukocyte count following standard procedures. At 10th and 40th week of age, 3 pullets were randomly selected from each group and placed in four different cages. The quantity of feed consumed and faeces voided were determined, proximately analyzed and used to determine the apparent digestibility of the diets. Eggs were collected three times daily, weighed and their external qualities were assessed. At the 20th week in lay, another set of 5 layers were randomly selected from each group and 5 ml of blood were collected from each bird and allowed to clot. The serum harvested was used to evaluate the serum biochemistry of the layers. At the 22nd week in lay, ten eggs were randomly selected from each group and were used to determine the egg cholesterol content. Five layers from each treatment group were randomly selected at the 70th week in lay, slaughtered and their gastrointestinal tract (GIT) carefully removed. The weight and length of the different sections of the gastrointestinal tract were determined.  At the 24th month of age,  another set of 5 layers were randomly selected from each group and used to evaluate the carcass quality. Repeat measure and one-way analysis of variance (ANOVA) were used to analyze the results. Variant means were separated using Duncan’s new multiple range test. Significance was accepted at p< 0.05. Group C birds had significantly (p<05) higher mean live weight than the group D birds (control). The PCV of group C birds was significantly higher (p < 0.05) than those of all other groups at weeks 9 and 15 of age. The group C birds also had significantly higher (p<0.05) TLC and lymphocytes counts than the control group (D). Apparent digestibility coefficient of dry matter, organic matter, crude protein and crude fibre were significantly (p<0.05) higher in the probiotic supplemented groups than the control. Group C had an overall significantly (p<0.05) higher hen-day egg performance of followed by groups B and A, while group D had the least hen-day egg performance. Birds in the supplemented groups had significantly higher (p<0.05) serum total proteins and significantly lower serum cholesterol when compared to the control. Eggs from the supplemented groups had significantly (p<0.05) lower cholesterol content when compared to the control. Group C birds had a significantly (p<0.05) longer colon than the control. There was no significant difference (p>0.05) in egg qualities (egg size, egg weight and shell thickness) between the supplemented groups and the control. The economic returns from sale of eggs was significantly higher (p<0.05) in group C birds in the first year of lay, but in the second year of lay, all supplemented groups had significantly higher (p<0.05) monthly revenue from eggs compared to the control. It was concluded that supplementation with probiotic S. cerevisiae significantly (p<0.05) enhanced pullet development, hen-day egg performance and monthly revenue from eggs, and significantly (p<0.05) lowered serum and egg cholesterol levels. The probiotic supplementation was most effective at the level of 1.0 g/kg of feed, and this is recommended.