US EPA

9417129 

Journal Article 

Dietary n-6/n-3 LC-PUFA ratio, temperature and time interactions on nutrients and fatty acids digestibility in Atlantic salmon 

Huguet, CT; Norambuena, F; Emery, JA; Hermon, K; Turchini, GM 

2015 

1 

Aquaculture
ISSN: 0044-8486
EISSN: 1873-5622 

436 

160-166 

10.1016/j.aquaculture.2014.11.011 

WOS:000346088200025 

The objective of the present study was to evaluate the effects of altered dietary n-3/n-6 LC-PUFA ratio, adaptation to diet over time, different water temperatures, and their interactions on nutrients and fatty acids digestibility in juvenile Atlantic salmon. Three experimental diets were formulated to be identical, with the only exception of the ratio of eicosapentaenoic acid (EPA, 20:5n-3) to arachidonic acid (ARA, 20:4n-6), and fed to triplicate groups of juvenile Atlantic salmon (Salmo salar) of 55 g initial body weight. Fish were reared in a fully controlled recirculating aquaculture system, fed to apparent satiety twice daily and kept at 10 degrees C and for an initial period of 100 days, and faeces were collected for digestibility estimation. Then, half of the fish of each experimental tank were moved to a separate system, where the water temperature was gradually increased up to 20 degrees C. Fish were maintained in the two systems for an additional period of 50 days, and faeces were collected for digestibility estimation from both groups of fish at the two water temperatures. This study concluded that dietary treatments and time had only minor effects, whereas environmental temperature resulted in modified digestibility values, with increased nutrient digestibility with increasing temperature. Varying EPA/ARA ratio in the diet had only minor direct effects on digestibility, with no direct effect on overall nutrients digestibility, and fundamentally only statistically significant effects in the fatty acid digestibility of EPA and ARA themselves. Because of current increasing pressure for more efficient fish oil replacement strategies, increasing interest in dietary ARA in aquafeed and increasing relevance and occurrence of sub-optimal rearing temperature in commercial aquaculture, this study can be considered to be important as it provided a series of fundamental information, which are envisaged to be useful towards addressing these constraints and possible nutritional remedial strategies. (C) 2014 Elsevier B.V. All rights reserved. 

Arachidonic acid; Digestibility; Eicosapentaenoic acid; long-chain polyunsaturated fatty acids; Salmo salar; Water temperature