Abstract
Numerous studies on the replacement of fishmeal with plant protein sources in tilapias have been undertaken. In order to quantify the effect of replacing fishmeal with plant protein sources on the growth performance of tilapias, a meta-analysis approach was applied. Despite the high heterogeneity and funnel plot asymmetry, the meta-analysis showed that replacing fishmeal with plant protein sources has a significant positive effect on the growth performance of tilapias. Thus, tilapias appear to be preadapted to utilizing plant protein sources. Furthermore, the feed value, nutritional quality and cost of the commonly used plant ingredients (soybean, sunflower, canola, cottonseed, kikuyu and azolla meals) were explored. The Solver function in Excel was used to formulate least-cost diets using the plant meals. Azolla had the highest nutritional index (9.7436). This was attributed to its excellent amino acid profile that exceeded the requirements of tilapias. Nutritional index and feed value were lowest in kikuyu because of its poor amino acid profile as it registered the lowest amino acid index (0.4918). These results indicate that the amino acid profile is more important in the determination of nutritional quality than the percent protein content. Azolla and soybean meal are good candidates for the replacement of fishmeal in the diets of tilapias.