Replacing dietary fish oil with palm fatty acid distillate improves fatty acid digestibility in rainbow trout, Oncorhynchus mykiss, maintained at optimal or elevated water temperature

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

“…Accordingly, in the present study, it was clearly shown that lower water temperature was responsible for lower lipid digestibility, lower total fatty acids digestibility, but also lower total nitrogen free extracts, and consequently also lower total energy digestibility. These findings were consistent with previous studies on salmonids (Bogevik et al, 2010;Ng et al, 2004;Ng et al, 2010;Olsen and Ringo, 1998), and other species as well (Guerreiro et al, 2012;Peres and Oliva-Teles, 1999).…”

“…Thus, considering that the melting point of a lipid source is a key characteristic for its digestibility, it appears to be evident that any variations in environmental temperature, and thus a modification of the lipid fluidity (solid to fluid status) could directly impact its digestibility. This has been clearly demonstrated predominantly for SFA and MUFA (Ng et al, 2003;Ng et al, 2004;Ng et al, 2010;Olsen and Ringo, 1998), whereas PUFA have been reported to be susceptible to such modifications but to a lesser extent, most likely because of their much lower melting points. Interestingly, in the present study, an increased DHA apparent digestibility for fish at the higher temperature was recorded but, admittedly, this was a relatively minor (~0.5%) increase from a quantitative point of view, and DHA was also digested at a very high rate at low temperature.…”

“…Sub-optimal temperatures are increasingly encountered in aquaculture as the result of climate change related phenomena (Cochrane et al, 2009) and/or market forces driving farming of species in areas with environmental characteristics outside their optimal physiological range, such as the case of Atlantic salmon farming in Australia (Neuman et al, in press;Pecl et al, 2011a;Pecl et al, 2011b). Therefore the relationship between water temperature and dietary lipids/fatty acids digestibility in fish has attracted significant research interest (Emery et al, 2014;Guerreiro et al, 2012;Ng et al, 2010).…”

Compared to fish oil alone, a corn and fish oil mixture decreases the lipid requirement of a freshwater fish species, Carassius auratus gibelio

“…On the other hand, different dietary FA compositions may exert different effects on fish lipid metabolism, such as FA digestibility, catabolism, lipid transport and uptake, and so on (Morais et al, 2006;Turchini et al, 2009). In rainbow trout Oncorhynchus mykiss, Ng et al (2010) reported that FA digestibility was improved when dietary fish oil was partially replaced by palm FA distillate. Brown trout Salmo trutta showed a specific preferential order of absorption of the FA, preferring shorter over longer chain FA and preferring the more unsaturated to the more saturated FA (Turchini et al, 2005).…”

Towards the optimization of performance of Atlantic salmon reared at different water temperatures via the manipulation of dietary ARA/EPA ratio

“…Water temperature is known to directly affect several physiological processes in fish, from digestive physiology (Ng et al, 2010;Olsen and Ringo, 1998;Trullàs et al, 2015) to changes in the structure of cell membranes and in lipid metabolism (Hazel, 1984). For example, in rainbow trout (Oncorhynchus mykiss), it has been shown that a high environmental temperature reduces the accumulation of LC-PUFA and increases the deposition of saturated fatty acids (Hazel, 1979;Wodtke, 1978).…”