Summary

This study describes an experiment carried out in Swaziland to determine the effect of supplementing the diet of young chickens with different levels of spent yeast on weight gain, feed conversion efficiency and mortality.

The case study highlights an error sometimes committed in the design of poultry or animal feeding experiments where researchers neglect the effect of competition that occurs among chickens or animals when fed as a group, and assume that measurements from them can be analysed individually. Suggested remedies in experimental design are made for dealing with this problem.

Summaries of the results from this experiment indicate that there were no differences in weight gain or feed efficiency for chickens fed the different diets, but it was not possible to evaluate the statistical significance of the results. There was an indication of a slight effect on mortality which might have been significant had a larger number of chickens been used.