Different dietary ratios of processed cassava leaf and root for Nile tilapia: Effects on digestibility, growth performance, and production economy

Abstract

Cassava, a locally available and cost-effective feed ingredient, offers potential benefits for small-scale fish farming where conventional protein and energy sources may be limited. This study evaluated the effects of different dietary ratios of processed cassava leaf (CL) and root (CR) on digestibility, feed utilization, growth performance, and production economics of Nile tilapia. Five iso-nitrogenous and iso-caloric processed cassava-based diets were formulated: CL₀CR₀, CL₂₀CR₅₀, CL₂₀CR₇₅, CL₄₀CR₅₀, and CL₄₀CR₇₅, where the values 20 and 40 in CL denote the percentage level of CL protein replacing soybean cake protein, while 50 and 75 in CR denote the percentage level of CR starch replacing wheat starch in the control diet. Nile tilapia fingerlings with an average initial body weight of 2.1 ± 0.1 g were stocked in 250-L tanks in triplicate and reared for 14 weeks. The results of the study showed that fish fed CL₂₀CR₅₀ diet had higher (p < 0.05) dry matter (DM) and ether extract (EE) hindgut apparent digestibility coefficients (ADC) than others, but not from CL₀CR₀ and CL₂₀CR₇₅. Fish fed CL₂₀CR₅₀ diet revealed comparable growth performance and protein efficiency ratios to fish fed CL₀CR₀ and CL₂₀CR₇₅ but were different (p < 0.05) from others. The ratios of cost to benefit, gross profit margin, and return on investment were higher (p < 0.05) for fish fed CL₂₀CR₅₀ and CL₂₀CR₇₅ diets than others. In conclusion, CL₂₀CR₅₀ and CL₂₀CR₇₅ diets exhibited the highest ADC and feed utilization, resulting in optimal growth performance and economic returns, making them promising dietary options for Nile tilapia production.