Effect of Feed Protein:Lipid Ratio on Growth Parameters of African Catfish Clarias gariepinus after Fish Meal Substitution in the Diet with Bambaranut (Voandzeia subterranea) Meal and Soybean (Glycine max) Meal

Uchechukwu Enyidi,Juhani Kettunen,Jouni Vielma,Juhani Pirhonen

doi:10.3390/fishes2010001

Abstract

Fishmeal (FM) was substituted with soybean meal (Glycine max) (SBM) and bambaranut meal (Voandzeia subterranea) (BNM) in 10 experimental African catfish, Clarias gariepinus, diets. Feed formulation was designed using mixture model. The inclusion level of the three protein ingredients varied between 0% and 60%. Remaining 40% comprised of basal ingredients kept constant for all 10 feeds. African catfish of average initial weight 35.2 ± 0.9 g were fed with one of the treatment diets for 28 days. The protein:lipid ratios of the diets (range 1.5–3.4:1) were used in evaluating the feed utilization and growth of the fish. We found that catfish performances were mainly depending on ingredients and not the ratio itself. The protein:lipid ratios in the diets made of plant ingredients were high but SGR was low. Specific growth rate (SGR) increased with the increase of feed FM content, being ca. 5% day−1 with 60% FM diet but ca. 2% day−1 at both 60% BNM and 60% SBM diets. SGR was similar (3.5% day−1) with diets of 30% BNM or SBM inclusion with 30% FM. Feed conversion ratio increased from below 0.6 of the 60% FM diet up to 1.5 (60% SBM) and 1.7 (60% BNM). Protein efficiency ratio decreased linearly with increasing FM substitution, but protein productive value (PPV) was similar for catfish fed 60% FM diet and its 50% substitution with BNM or SBM. These results suggest that protein:lipid ratio cannot be used in assessing nutritional performance if the source of feed ingredient vary widely. However, these results suggest that BNM can partly substitute FM and completely replace SBM in the diets of African catfish.

Highlights

There is urgent need to make aquafeed production more cost effective
Protein efficiency ratio decreased linearly with increasing FM substitution, but protein productive value (PPV) was similar for catfish fed 60% FM diet and its 50% substitution with BNM or Soybean (Glycine max) meal (SBM). These results suggest that protein:lipid ratio cannot be used in assessing nutritional performance if the source of feed ingredient vary widely
The protein:lipid ratios of the diets containing vegetable proteins, F5, 2.4:1, F6, 3.0:1, and F8, 2.8:1, seems to support nutrient utilization and growth resulting in specific growth rate of 3.77 ± 0.80% day−1, 3.74 ± 0.57% day−1 and 3.94 ± 0.82% day−1, respectively (Table 1)

Summary

Introduction

Fishmeal is the most costly feed ingredient and is very expensive as an imported item [1]. The development of adequate plant protein and oil sources as substitutes to fishmeal (FM) and fish oil will reduce aquaculture pressure on dwindling forage fisheries [1]. Soybean (Glycine max) meal (SBM) is the major plant ingredient utilized for fish feeds [3], and it is currently the primary. Fishes 2017, 2, 1 plant protein in catfish diets in Africa [4]. E.g., groundnut (Arachis hypogaea) cake [5], bambaranut (Voandzeia subterranea) meal [6] and cottonseed (Gossypium sp.) cake [7], have been evaluated for replacing fish meal in diets of African catfish, Clarias gariepinus. Multiple usages have rendered soybean competitively scarce and expensive for sub-Saharan Africa aquaculture industry [4,8]

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Discussion

Conclusion