Optimum Dietary Ca/P Ratio and Phytase for Growth and Bone Mineralization in Juvenile Clarias gariepinus Fed Soya Bean-Based Diet

Akpoilih Bu,Ajani Ek

doi:10.4172/2155-9546.1000403

Abstract

The research investigated the interactive effect of five phytase graded levels of 0 FTU/g (P0), 250 FTU/g (P1), 500 FTU/g (P2), 750 FTU/g (P3), 1000 FTU/g (P4) and four graded levels of roasted soya bean substitution at 25%, 50%, 75% and 100% in place of fish meal, respectively. All basal diets contained 0.20% calcium without added inorganic phosphorus, wheat and amino acids supplements so that the phosphorus, calcium, and Ca/P ratios of the five (5) were: S0 (1.31%, 1.85%, and 1.41), S1 (1.15%, 1.64%, and 1.43), S2 (1.01%, 1.28%, and 1.27), S3 (0.75%, 0.99%, and 1.30), and S4 (0.43%, 0.68%, and 1.59). 1092 fish of average weight 11.55 ± 0.2 g were randomly allocated to all experimental diet and fed 3% body for 84 days. There was no significant difference in final weight, weight gain and FCR S3P1 and S0P0 (P>0.05). Fish fed low phosphorus diet (100% soya bean) showed reduced total weight and weight gain compared to high (0%, 25%, 50%) and medium phosphorus diet (75%) with phytase addition (P 0.05), and PER (r=-0.210, P>0.05). Ca/P of S3P1 (1.41 ± 0.02) was not different from S0P0 (1.41 ± 0.01). Bone phosphorus, calcium and zinc were higher in 250 FTU/g compared to 0 FTU/g, 500 FTU/g, 750 FTU/g and 1000 FTU/g. In conclusion, Phytase improved growth performance (r=0.05) of juvenile Clarias gariepinus with optimum at 250 FTU/g; however, Ca/P affected performance (r=-0.431) and should range between 1.41-1.46 for optimum phytase activity.

Highlights

The main source of plant protein in terrestrial and aquatic feed includes soybean meal, corn, groundnut meal, sunflower meal, canola/rapeseed meal, peas and lupins [1]
Cao et al reported that the growth and feed conversion efficiency in commonly cultured fish species, such as carps, tilapias, trout and salmons were negatively affected by the phytate in the diets [7]
Optimum phytase has been determined for Channel catfish [13,14], Nile tilapia [15], Korean rockfish [16], Pangasius pangasius [17], and Rainbow trout [18]

Summary

Introduction

The main source of plant protein in terrestrial and aquatic feed includes soybean meal, corn (gluten), groundnut meal, sunflower meal, canola/rapeseed meal, peas and lupins [1]. The major constraints that limit use of plant proteins in animal feed are the presence of anti-nutritional factors such as saponins [3], lectins (Santiago et al.), and phytate being one of importance [1]. They are limiting in essential amino acids affecting growth and nutrient utilization in fish [4]. Very low phytase activities have been reported for legume seeds, dietary supplementation is necessary in oil seed meals, soy bean meal to improve protein and mineral digestibility and availability, which is very low compared to fish meal [10]. Wheat has a high phytase (1193 FTU/g), according to Eeckhout and de Paepe (1994) [47], which can compromise responses to phytase and reduce its efficacy

Methods

Results

Conclusion