University of Tasmania
whole_KroghPeterKenneth1997_thesis.pdf (4.68 MB)

Apparent digestibility coefficients of feed raw materials for barramundi Lates calcarifer (Bloch)

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posted on 2023-05-26, 20:34 authored by Krogh, PK
This study was undertaken to define the availability of different nutrients within feed raw materials for the tropical species barramundi Lates calcarifer (Bloch). Availability was measured as the apparent digestibility coefficient (A.D.C.) measured as the difference in composition between feed and faeces. Feed materials investigated include blood meal, fish meals, meat and bone meal, soy meal, soy protein meals, yeast meal, squid meal, prawn shell meal and wheat. Initial trials were conducted to determine the best method for faecal collection, including continual filtration and stripping. Individual aquariums holding ten fish were connected to purpose built filtration units for the collection of faeces. Experiments one, two and four used the method of continual filtration of faecal material to determine the apparent digestibility coefficient of raw materials, using fish with a mean weight of 396.65+/- 65g. Considerable variation was found in protein and lipid A.D.C.s for the ingredients tested. Fish meals tested had significantly different absorption efficiencies. Experiment two assessed the effect of temperature on faecal collection chambers. No differences were found on the nutritional parameters of crude protein and crude lipid. Experiment three, carried out with experiment four was a practical evaluation of A.D.C.s for crude protein and crude lipid of a reference diet with faeces collected by continual filtration and stripping. Experiment four assessed production method for diet manufacture found a significant difference between the methods of cold extrusion and steam pelleting. Different processing techniques of raw materials and of finished diets and their effect of apparent digestibility coefficient are discussed. Results from this study were used to formulate a diet for barramundi using commercial production techniques, for trialing with existing commercial banamundi feeds. Results from this six week trial indicated that through the use of protein and lipid A.D.C.s the reformulation of diets for barramundi can see significant savings to the barramundi farming industry. Growth rates and food conversion rates were comparable to existing commercial diets but at a 'greatly reduced cost. In all experiments faecal material was collected daily, analysed and used to calculate apparent digestibility coefficients. Results are also compared with existing information available on cold water species to elucidate any major differences.


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Copyright 1996 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s). Thesis (M.App.Sci.)--University of Tasmania, 1997. Includes bibliographical references

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