Genet. Sel. Evol. 38 (2006) 389-409
DOI: 10.1051/gse:2006011

Recording strategies and selection potential of feed intake measured using the X-ray method in rainbow trout

Antti Kause^a, Declan Tobin^b, Alexandre Dobly^b, Dominic Houlihan^b, Sam Martin^b, Esa A. Mäntysaari^a, Ossi Ritola^c and Kari Ruohonen<sup>d

a</sup>  MTT Agrifood Research Finland, Animal Production Research, Animal Breeding, FIN-31600 Jokioinen, Finland
^b  School of Biological Sciences, Department of Zoology, University of Aberdeen, Aberdeen, AB24 2TZ, United Kingdom
^c  Finnish Game and Fisheries Research Institute, Tervo Fisheries Research and Aquaculture, FIN-72210 Tervo, Finland
^d  Finnish Game and Fisheries Research Institute, Turku Game and Fisheries Research, FIN-20520 Turku, Finland

(Received 4 November 2005; accepted 27 March 2006; published online 23 June 2006)

Abstract - This study examines the way long-term feed intake should be recorded accurately for selective breeding purposes, and estimates selection potential in feed intake using the X-ray method to record individual daily feed intake in rainbow trout (Oncorhynchus mykiss). The analysis showed that the point estimates of daily feed intake displayed low repeatabilities ( r = 0.09-0.32). This indicates that a minimum of three repeated records were needed to accurately record average feed intake at a fixed age. To effectively breed for feed intake over the whole growing period, it is necessary to determine average feed intake at different ages, since there were only moderate phenotypic and genetic correlations between average daily feed intake recorded at 140 g, 750 g and 2000 g wet mass. Heritability for average daily feed intake was low (average h² = 0.10), indicating that modest genetic changes can be obtained in response to selection. It was concluded that selection to genetically change long-term feed intake can be successful, yet repeated observations at several life stages are needed to ensure the accuracy of feed intake estimates and the efficiency of selection.

Key words: feed efficiency / X-radiography / heritability / repeatability / salmonids

Correspondence and reprints: Antti.Kause@mtt.fi

© INRA, EDP Sciences 2006