Mp Bransden

Replacement of fish oil with sunflower oil in feeds for Atlantic salmon (Salmo salar L.): effect on growth performance, tissue fatty acid composition and disease resistance.

Dietary sunflower oil (SFO) was used to gradually replace fish oil (FO) in six diets (which also contained fish meal) for Atlantic salmon parr (initial mass: 21.7 g). The effect on growth performance, tissue fatty acid profiles and disease resistance was monitored after 63 days. At the conclusion of the trial, no significant differences were detected in growth between any of the feeds. Fatty acid composition of whole carcass, dorsal muscle and liver generally reflected that of the diets. Forty percent of the FO could be replaced by SFO before tissue 22:6n-3 was significantly reduced, although other essential and non-essential fatty acids were more susceptible to change. Significant differences were detected in cumulative mortality of Atlantic salmon challenged with Vibrio anguillarum at the trials conclusion, although this was not correlated to the inclusion level of SFO. Despite the changes observed to the tissue fatty acid profile, there was no significant effect on growth suggesting that SFO is a suitable alternative to FO in diets for Atlantic salmon parr when fish meal is also included.

Potential of Thraustochytrids to Partially Replace Fish Oil in Atlantic Salmon Feeds

AbstractThe replacement of fish oil with a dried product made from thraustochytrid culture, a marine microorganism, in canola-oil-based diets for Atlantic salmon was investigated. Salmon (37 g) were fed for 51 days on diets containing only canola oil, canola oil and fish oil, or canola oil and the thraustochytrid. There were no significant differences in final weight (106.1 ± 1.1 g), weight gain (69.6 ± 1.1 g), feed consumption (16.5 ± 0.2 mg dry matter g-1 d-1), feed efficiency ratio (1.15 ± 0.03 g g-1), or productive protein value (51.2% ± 1.7%) between the diets. Nor were there any significant differences in whole-body chemical composition, organ somatic indices, or measures of immune function. However, following transfer to seawater and 2 challenges with Vibrio anguillarum, cumulative mortality was significantly lower in fish fed some fish oil than in those fed the 2 diets containing no fish oil. In conclusion, the thraustochytrid had no detrimental effects on the performance of salmon but, at the current inclusion of 10%, failed to confer the same effect as fish oil under challenging conditions.

Effects of dietary protein source on growth, immune function, blood chemistry and disease resistance of Atlantic salmon ( Salmo salar L.) parr

Many studies with fin fish have demonstrated the potential to use alternative dietary protein sources to fish meal based on growth responses, although these trials mostly neglect to determine if such protein sources affect immune function. This study investigated the effect of fish meal replacement with dehulled lupin meal (LPN) or hydrolysed poultry feather meal (FTH). Atlantic salmon ( Salmo salar L.) parr were supplied isonitrogenous and isoenergetic diets with 40% of the dietary protein provided by LPN or FTH, or 400 g/kg of the dietary protein provided equally by LPN and FTH (MIX). A diet mainly containing fish-meal protein acted as a control (CON). Growth, immune function, blood chemistry and disease resistance were assessed after 56 days. Significant differences ( P < 0.05) in weight gain were detected between Atlantic salmon given the CON and FTH diets, whilst those salmon given LPN and MIX did not differ from any other. Productive protein values were significantly lower ( P < 0.01) for salmon on FTH compared with those on CON and MIX. Immune function (as assessed by lysozyme, antiprotease, neutrophil oxygen radical production and plasma total immunoglobulin) and blood chemistry (as assessed by plasma total protein and glucose) were not significantly ( P > 0.05) affected by any diet. Mortality rates of Atlantic salmon challenged with Vibrio anguillarum were not influenced by diet. These data suggest Atlantic salmon could be supplied diets with the fish meal component reduced to supply approximately 600 g/kg of the total protein, with the remaining 400 g/kg supplied by dehulled lupin meal or a combined dehulled lupin and hydrolysed poultry feather meal without any adverse effects on growth, immune function or blood chemistry.

Alternative methods for nutrition research on the southern bluefin tuna, Thunnus maccoyii: in vitro digestibility

Abstract Southern bluefin tuna is an important mariculture species in Australia but the development of manufactured feeds has been limited by the lack of detailed information on their nutrition. Although pelleted feeds have been developed progress has been slow. Feeding trials are difficult, time consuming and very expensive, thus complementary research methods using in vitro digestibility were developed and assessed in order to more rapidly achieve a viable manufactured feed. The in vitro crude protein and dry matter digestibility of ingredients and feeds using three enzyme systems based on purified commercial, Atlantic salmon or southern bluefin tuna digestive enzymes, were compared. Crude protein digestibility was higher than dry matter digestibility and values were highest using commercial enzymes, then using crude extracts from Atlantic salmon and lowest using crude extracts from tuna. However, the three enzyme systems gave similar relative values and were significantly ( P P

Influences of dietary n-3 long-chain PUFA on body concentrations of 20 : 5n-3, 22 : 5n-3, and 22 : 6n-3 in the larvae of a marine teleost fish from Australian waters, the striped trumpeter (Latris lineata)

We determined the effect of dietary long-chain (≥C20) PUFA (LC-PUFA), 20∶5n−3 and 22∶6n−3, on larval striped trumpeter (Latris lineata) biochemistry through early development and during live feeding with rotifers (Brachionus plicatilis). Rotifers were enriched using seven experimental emulsions formulated with increasing concentrations of n−3 LC-PUFA, mainly 20∶5n−3 and 22∶6n−3. Enriched rotifer n−3 LC-PUFA concentrations ranged from 10–30 mg/g dry matter. Enriched rotifers were fed to striped trumpeter larvae from 5 to 18 d post-hatch (dph) in a short-term experiment to minimize gross deficiency symptoms such as poor survival that could confound results. No relationships were observed between larval growth or survival with dietary n−3 LC-PUFA at 18 dph. The larval FA profiles generally reflected those of the rotifer diet, and significant positive regressions were observed between most dietary and larval FA at 10, 14, and 18 dph. The major exception observed was an inverse relationship between dietary and larval 22∶5n−3. The presence of 22∶5n−3 in elevated amounts when dietary 22∶5n−3. The presence of 22∶5n−3 in elevated amounts when dietary 22∶6n−3 was depressed suggests that elongation of 20∶5n−3 may be occurring in an attempt to raise body concentrations of 22∶6n−3. We hypothesize that accumulation of 22∶5n−3 might be an early indicator of 22∶6n−3 deficiency in larval fish that precedes a reduction in growth or survival. A possible role of 22∶5n−3 as a biochemical surrogate for 22∶6n−3 is discussed.

Relationships between protein–nitrogen flux and feeding regime in greenback flounder, Rhombosolea tapirina (Günther)

This study aimed to measure protein synthesis and growth performance in flatfish, Rhombosolea tapirina, fed on three feeding regimes: 1% body wt. fed in the morning (MM1); 2% body wt. fed in the morning (MM2) and 2% body wt. fed in equal amounts in the morning and in the afternoon (MA2). After 6 weeks there were no significant differences in wet wt., protein growth or efficiency of protein-nitrogen flux. Significantly lower protein consumption on MM1 resulted in significantly lower rates of protein synthesis and degradation compared with MM2 but not MA2. After 18 weeks there were still no significant differences between feeding regimes although trends in growth and efficiency reflected the situation after 6 weeks. Fish were maintained individually, and when analysed on this basis, there were significant relationships between protein consumption and protein synthesis [k(s)=0.92, k(r)+1.16 (n=17; r(2)=0.49; P<0.005)], between protein consumption and protein degradation [k(d)=0.82, k(r)+1.06 (n=17; r(2)=0.41; P<0.005)] and between average daily protein consumption and protein growth [k(g)=0.15, k(rx)-0.15 (n=17; r(2)=0.75; P<0.001)]. Thus, increasing protein consumption resulted in increased protein synthesis and growth. However, the combination of high rates of protein synthesis and protein degradation in relation to protein consumption, and resulting high anabolic stimulation and low retention of synthesised protein, contributed to the low growth performance of greenback flounder.