Yeast extract as partial replacement for fish meal in broiler diets

The effect of partial. or total replacement of fish meal, a traditional animal protein source, with yeast extract was investigated using 400 1-d-old broiler chicks randomly distributed into 4 treatment groups: diet I - basal diet with 3% fish meal (negative control); diet II - basal diet with 2% fish meal and 1% yeast extract; diet III - basal diet with 1% fish meal and 2% yeast extract; and diet IV - basal diet with 3% yeast extract (positive control). The starter diet was fed from 7 d to 28 d of age and the grower diet from 29 d to 49 d of age. Birds fed with diet II had the highest average live body weights, weight gains and feed conversion ratios. All birds fed with diets containing yeast extract (diets II, III and IV) had significantly higher average live body weights and body weight gains, and better feed conversion ratios than those fed fish meal alone. No significant differences were noted in the feed consumption, mortality and livability rates, dressing percentage and percent abdominal fat of birds in all dietary treatments. Despite the increase in feed cost with the addition of yeast extract, income from diet II was highest due to the significantly higher live body weights. This study demonstrated that yeast extract could be used to replace part of the fish meal in broiler feed.