Abstract
1. The effects of enzymatically hydrolysed whole Saccharomyces cerevisiae yeast (HY) and the pellets of yeast cell wall (YCW) on production traits, the microbiology and histo-morphology of the small intestine, and humoral immune responses against Newcastle disease virus (NDV), of Ross 308 broilers were investigated.
2. The control group received a maize-soyabean meal based basal diet for 42 days. In the treated groups the basal diet was supplemented with 1 g/kg of HY and YCW. There were 8 replicate pens per group (n = 12 birds/pen).
3. HY and YCW supplementation improved live weight (P = 0·006) and FCR (P = 0·003) at 42-d as compared with the control group.
4. In the small intestine, Salmonella spp and Escherichia coli numbers were higher (P = 0·01) in the mucosa and lower (P = 0·01) in the digesta of the HY and the YCW fed groups at 25 d of age. Lactobacillus in the duodenal and jejunal digesta was higher (P < 0·05) in the HY and the YCW fed groups as compared with the control.
5. Following oral challenge with Salmonella pullorum, Escherichia coli and Lactobacillus increased (P < 0·05) in the mucosa and decreased in the digesta (P < 0·05) of the HY and YCW supplemented groups, relative to the control.
6. Supplementation of HY and YCW increased villus height in the jejunum (P = 0·02), width of villus in the ileum (P = 0·034) and number of goblet cells in villi of the jejunum (P = 0·006) and ileum (P = 0·01).
7. YCW increased antibody level against NDV at 21 and 42 d of age compared with the control and the HY supplemented diets (P < 0·05).
8. It was concluded that HY and YCW improved growth and feed efficiency in broilers, and considering the improvements in production traits and humoral immune responses, yeast cell wall may be a better dietary tool than the hydrolysed whole yeast cell as a performance enhancer for broilers.
Acknowledgement
The authors acknowledge the financial aid received from AB Vista, Marlborough, Wiltshire, United Kingdom, SN8 4AN, for conducting the research.