Discipline: Animal Science
Protein sources of feeds are becoming more expensive and less available due to the outbreak of diseases such as Foot and Mouth Disease and Mad Cow Disease. In this study, the effect of partial or total replacement of fish meal, a traditional protein source, with yeast extract was investigated in a total of 400 day-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% fishmeal and 1 % yeast extract; Diet III - basal diet with 1% fishmeal and 2% yeast extract; and Diet IV - basal diet with 3% yeast extract (positive control). The starter diet was fed from 7 days to 28 days of age and the grower diet, from 29 days to 49 days of age. Birds fed Diet II had the highest average live body weights, body weight gains and feed conversion ratios. All birds fed diets containing yeast extract (Diets II, III, 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 difference was 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 as part or total replacement of fishmeal in broiler feed. However, a combination of both types of protein is recommended.