whole_WardDonaldAlan2003_thesis.pdf (15.11 MB)
Mineral and trace element nutrition in salmonids
thesisposted on 2023-05-27, 15:39 authored by Ward, DA
Minerals and trace elements are essential constituents in any diet. Our understanding of the requirements of minerals and trace elements in salmonids is limited, and based on information gained through the use of purified feeds. There exists a need to define standardised methods for determining the apparent digestibility coefficients (ADC) of minerals (calcium, iron, phosphorus, sodium, potassium, sulphur and magnesium) and trace elements (aluminium, boron, cadmium, cobalt, copper, manganese, molybdenum, nickel, selenium, vanadium and zinc), the relation between ADC and mineral retention and the effects alternative dietary protein sources, particularly those derived from plants, have on mineral and trace element ADC in salmonids. The primary objective of this research is to improve our understanding of how to best observe the nutritive value of essential minerals and trace elements and their interactions in salmonid diets. Part 1 dealt with the methodology of determining the ADC of minerals and trace elements by comparing external digestibility markers (chromium oxide and yttrium oxide) and an internal marker (acid insoluble ash) and measured the effect of faecal collection timing on ADC. High recovery marker rates and low variation in digestibility values indicated that including yttrium oxide at 0.1% effectively determined ADC for all minerals and most trace elements. Significant differences in mineral and trace element ADC were observed under the various sampling protocols, and an 18 hour collection period provided the most reliable ADC. Part 2 sought to determine the strength of relationships between digestibility and retention of minerals and trace elements and establish data for expected tissue concentrations and mineral status of salmon. There was a complex range of diet and time effects that varied between tissues. The statistical power of determining the effect of mineral supplementation varied by element, and reflected ADC. There were no differences in growth performance between feed composed of various levels of mineral supplementation so the results provide baseline data on mineral status in relation to requirements and uptake. Part 3 dealt with the effect of plant ingredients on ADC, mineral retention, intake and growth, and compared methods of measuring maximum voluntary intake. Mineral and trace element ADC for plant ingredients differed between and amongst species. Lupin‚ÄövÑvÆbased feeds provided growth similar to that provided by a fish meal based feed, but displayed significantly different ADC and maximum voluntary intake. The concentration of particular minerals and trace elements in plant ingredients was reflected in ADC, carcass concentrations, but not in calculated retention values.
Rights statementCopyright 2003 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 (Ph.D. )--University of Tasmania, 2003. Includes bibliographical references