Maintenance threonine requirement and efficiency of its use for accretion of whole-body threonine and protein in Atlantic salmon ( Salmo salar L.) fry
Eighteen groups of seventy Atlantic salmon ( Salmo salar L.) fry (initial mean body weight 0·8 (sd 0·01) g) were fed on semi-purified diets containing graded levels of l-threonine (Thr) in 15 litres aquaria at a temperature of 14·5±1°C. Doses of Thr represented 1, 31, 41, 51, 62, 72, 83 and 93% of i...
| Published in: | British Journal of Nutrition |
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| Main Authors: | , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
2006
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1079/bjn20051491 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0007114506000316 |
| Summary: | Eighteen groups of seventy Atlantic salmon ( Salmo salar L.) fry (initial mean body weight 0·8 (sd 0·01) g) were fed on semi-purified diets containing graded levels of l-threonine (Thr) in 15 litres aquaria at a temperature of 14·5±1°C. Doses of Thr represented 1, 31, 41, 51, 62, 72, 83 and 93% of its ideal level for optimumprotein deposition. Indispensable amino acids other than Thr were included in the same proportion (on a g/16g N basis) as in the Atlantic salmon fry whole-body carcass. Following 36d of feeding and a 36h fast, fry were killed for whole-body protein and amino acid analysis. Weight gain ( r 2 0·98), protein accretion ( r 2 0·97), and Thr accretion ( r 2 0·97) were linear ( P <0·01) functions of Thr intake. Slope of the Thr accretion regression line showed that the efficiency of Thr utilisation above maintenance was 76%. At zero Thr intake, fry lost 5·4mg Thr/kg body weight 0·75 per d. The Thr maintenance requirement was 7·2mg/kg body weight 0·75 per d and the Thr requirement for growth was 66mg for 1g protein deposition. Increasing doses of Thr resulted in increased ( P <0·05) concentrations of histidine and lysine, and decreased concentrations of isoleucine in whole-body protein. The maintenance need for Thr represented 13·4% of the total need for Thr. The data suggest that efficiency of Thr utilisation above maintenance is constant at all levels of Thr intake between 1 and 93% of the level required for optimum protein deposition. |
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