LARVAL FEED ALTERNATIVES INTRODUCTION

LARVAL FEED ALTERNATIVES 
Phil Boeing 

CONTENTS
• Introduction
• Algae Rotifers
• Artemia nauplii
• Ongrown Artemia
• Nematodes
• Crustacean
• Tissue Suspension
• Summary
• Rotifers
• Artemia nauplii
• Nematodes Algae
• Crustacean tissue suspension
• Recommendations


INTRODUCTION 

There are two major reasons why non-living produced feeds for rearing larvae of aquatic animals do not yet have an advantage over live food organism. These are: rapid deterioration of water quality due to disintegration of micropellets, which are usually fed in excess in order to achieve satisfactory growth and survival; high mortality rates, due to malnutrition and/or incomplete digestion of diet components. Cultivation of larval stages of various aquaculture species is still highly dependent on live food which is for herbivorous larvae, like molluscs and crustaceans, a fairly understood task. Many more difficulties have to be faced when live food animals are required, as is mainly the case in fish rearing, but holds true for latter stages of crustacean larvae as well. The reason why live food is so essential for larval growth has not yet been clearly defined. Enzymes present in phyto and zooplankton but not synthesized by the physiological system of a larvae are probably important. Also of importance are several essential biochemical compounds such as poly-unsaturated fatty acids, most of which have been defined as to species requirements. Primary producers of these fatty acids such as algae and bacteria form the base of the trophic pyramid, and as such constitute the largest link in the aquatic food chain. The largescale, intensive production of microalgae and rotifers suffers from two major problems: it is expensive and often unreliable. Contributing to the problem is the fact that designs used for experimental and pilot scale units, which are the bulk of the published research, are usually inappropriate for larger system because of logistical problems, prohibitive cost of materials, or diminishing surface area to volume relationships which affect scale up performance. Scale up problems can arise in the bulk handling of materials such as animals, water and feeds which in a restricted laboratory situation are easily transported and held in small containers. Carrying out necessary life support functions can also become complicated, since daily work routines for large numbers of animals quickly becomes prohibitive. Routine maintenance and cleaning of culture units, while trivial in the laboratory becomes a major problem with increased scale. As hatchery managers try to stem the rising costs of production, the economic cultivation of live feeds or some alternative becomes ever more important. The sections that follow will attempt to illuminate various options and potentials for larval penaeid shrimp feeds. The summary section will then rate the most cost effective choices for management consideration.

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