The Feeding value and protein quality in high-fibre and fibre-reduced sunflower cakes and Kenya's “Omena” fishmeal for tilapia (Oreochromis niloticus)

Abstract

This study was undertaken to assess the nutritive values of some locally available protein sources in Kenya, as replacements for anchovy fishmeal in tilapia diets. The test protein sources were omena fishmeal made from Rastrineobola argentea, anchovy fishmeal, as well as fibre-reduced and high-fibre sunflower cakes. The four protein sources were each tested at two protein concentrations. Oreochromis niloticus fingerlings with an initial weight of 16 g. were used for the study. Eight experimental diets, four based on fishmeal and four on sunflower cake were formulated. Each diet contained one of two levels of protein, viz., approximately 20% (low-protein) and 30% (high-protein). Further, each diet was fed to triplicate groups of fish for 78 days.

Diets based on the fibre-reduced cake had higher levels of all amino acids than the ones based on the high-fibre cake. Lysine and threonine concentrations were lower in diets based on the sunflower cakes than the ones based on the fishmeals. Fish fed diets with 20% protein gained less weight and had higher feed:gain ratios than those fed diets with 30% protein. Fish fed diets based on anchovy fishmeal had higher weight gains than those fed diets based on the high-fibre sunflower cake. Reducing the fibre content of sunflower cake improved growth rate and weight gain. Growth rates and weight gains of fish fed diets based on the two fish meals were not significantly different.