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.
Highlights
Feed is one of the major costs in farm animal production
This study examined the way long-term feed intake should be recorded in rainbow trout (Oncorhynchus mykiss Walbaum) for selective breeding purposes, and estimated selection potential in feed intake
There was no difference between the diets in the repeatabilities of body weight. These results indicate considerable amounts of measurement noise for repeated daily feed intake measurements, but clearly less for body mass measurements
Summary
Feed is one of the major costs in farm animal production. In aquaculture, improving feed efficiency, a ratio of wet mass gain to feed intake, would have the effect of reducing feed costs and minimising environmental loading. Selective breeding is a potential tool for improving feed efficiency. Feed efficiency can be improved by simultaneous selection for rapid growth and against feed intake, or, when growth rate and feed efficiency are favourably genetically correlated, by sole selection for increased growth rate [21]. Since feed intake is a fundamental component of feed efficiency, reliable means of recording feed intake are required. This study examined the way long-term feed intake should be recorded in rainbow trout (Oncorhynchus mykiss Walbaum) for selective breeding purposes, and estimated selection potential in feed intake
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