The whole-body transcriptome of trout alevins was characterised to investigate the effects of long-term feeding of rainbow trout broodstock females a diet free of fishmeal and fish oil on the metabolic capacities of progeny. Effects were studied before first feeding and after 3 weeks of feeding diets containing different proportions of marine and plant ingredients. Feeding alevins plant-based diets resulted in lower fish body weight, irrespective of maternal nutritional history. No differences in whole-body lipids were found between treatments, and the tissue fatty acid profile strongly reflected that of the respective broodstock or first-feeding diets. We showed that the maternal diet history did not significantly affect expressions of any genes before the first feeding. Interestingly, we found an effect of maternal nutritional history on gene expression in alevins after 3 weeks of feeding. The major differences in the transcriptome of alevins from plant-based diet-fed females compared with those from commercial-fed females were as follows: (i) down-regulation of genes involved in muscle growth/contraction and (ii) up-regulation of genes involved in carbohydrate and energy metabolism related to the delay in growth/development observed with plant-based diets. Our findings also showed an effect of the first-feeding diets, irrespective of maternal nutritional history. Specifically, the introduction of plant ingredients resulted in the up-regulation of genes involved in amino acid/protein and cholesterol metabolism and in differences in the expressions of genes related to carbohydrate metabolism. Information gained through this study opens up avenues for further reduction of marine ingredients in trout diets, including the whole rearing cycle.

We studied the effects of the frequently used glucogenic dietary supplementation in dairy herds and the hormonal changes occurring during the normal estrous cycle on the composition and concentration of milk lipid components. Holstein dairy cows were synchronized with two injections of prostaglandin F2α (estrus=day 0). Animals were held as controls or drenched for 11 days (day −3 to day 8 of the cycle) with 850 ml/day liquid propylene glycol (treatment, n=13 per group). Blood and milk samples were collected on day 1 and 8 of the cycle. In both groups, plasma progesterone concentration increased ∼10-fold between 1 and 8 days post-estrus. Milk fatty acid composition was associated primarily with estrous-cycle day: polyunsaturated fatty acids increased by 16%, n-6 by 15% and n-3 by 1% from day 1 to 8 post-estrus. Polar lipid composition was also altered by cycle day: phosphatidylethanolamine concentration was 2-fold and 1.5-fold higher on day 1 v. day 8 post-estrus in the control and treatment groups, respectively. Phosphatidylserine concentration in milk was also affected by cycle day by treatment interaction (P=0.04). A progesterone level by treatment interaction influenced the triglyceride-to-phospholipid ratio in the milk (P=0.02). The results suggest that progesterone plays a role in modulating milk lipid composition and structure. Therefore, strategies designed to alter milk lipid composition should consider the cow’s reproductive status.

This study investigated effects of roasted or extruded oilseed supplementation ranging in n-6/n-3 ratios from 0.3 to 5.0 on the fatty acid composition and expression of delta-5 desaturase (Δ5d) and Δ6-desaturase (Δ6d) protein in commercial steer cheek (m. masseter) and diaphragm (pars costalis diaphragmatis) muscles. In general, the n-6/n-3 ratio of the diet had a subsequent effect on the muscle n-6/n-3 ratio (P < 0.05), with muscle 18:2n-6 and 18:3n-3 content relating to proportion of dietary soya bean and linseed (P < 0.01). Compared with canola, pure linseed and soya bean diets reduced 14:1c-9 and 16:1c-9 (P < 0.05) but increased 18:1t-11 and c-9,t-11 conjugated linoleic acid (CLA) content (P < 0.01). Oilseed processing had a minor influence but extruded oilseeds increase 18:1t-11 and c-9,t-11 CLA compared with roasted (P < 0.05). Polar lipid 18:3n-3 and n-3 long-chain polyunsaturated fatty acid (LC, ⩾20 carbons PUFA) derivative content increased in relation to dietary linseed supplementation in the diaphragm (P < 0.01), whereas only 18:3n-3 was increased in the cheek (P < 0.01). Protein expression did not differ between diets; however, in each muscle the Δ5d protein expression had a stronger association with the desaturase products rather than the precursors. The relationship between Δ5d protein expression and the muscle LC n-6/n-3 ratio was negative in both muscles (P < 0.05). The relationship between Δ6d protein expression and the LC n-6/n-3 ratio was positive in the cheek (P < 0.001) and negative in the diaphragm (P < 0.05). In conclusion, diet n-6/n-3 ratio affected muscle 18:2n-6 and 18:3n-3 deposition, whereas the Δ5d and Δ6d protein expression had some influence on the polar lipid LC-PUFA profile. Results reaffirm that processed oilseeds can be used to increase the proportion of fatty acids potentially beneficial for human health, by influencing the formation of LC-PUFA and reducing the n-6/n-3 ratio.

Krill are thought to be predominantly herbivorous, but a heterotrophic diet might be crucial for their growth and survival. To compare the influence of herbivory and carnivory on krill we conducted a nine month feeding trial. We examined lipid composition of the hepatopancreas, abdomen and remaining body portions of krill fed diatoms at bloom condition levels, and diatoms with the addition of pellets or minced clam meat to simulate a partly carnivorous diet. Mortality, dry mass and lipid content were similar among treatments. We examined lipid class and fatty acid profiles, with emphasis placed on the ratio of storage (triacylglycerol) to structural (polar lipid) lipid and key essential omega 3 polyunsaturated fatty acids: 20:5ω3 and 22:6ω3. The triacylglycerol : polar lipid ratio increased in krill fed on the mixed diet as did the 20:5ω3 : 22:6ω3 ratio. Overall these findings indicate that provision of clam in the diet improved krill condition, and further suggest that carnivory may aid krill growth in the wild under certain environmental conditions.

Se estudió de contenido en ácidos grasos de los lípidos totales, polares y neutros en músculo, hepatopáncreas y ovario de hembras de Penaeus kerathurus antes y después de la puesta. El ovario fue el organo que presentó un mayor descenso del contenido lipídico total (50,9%), que se transfirió a los huevos durante la oogénesis. En los diferentes organos estudiados, el contenido de lípidos polares fue superior al de lípidos neutros. Sin embargo, durante la puesta se transfirieron mayores cantidades de lípidos neutros que de polares tanto en el ovario como en el hepatopáncreas. El contenido de los ácidos grasos saturados de los lípidos totales del ovario disminuyó un 66,3%, el de monoinsaturados un 56,5% y el de los poliinsaturados un 62,6%. Acidos grasos como el 16:0, 16:1 n − 7 y 18:1 n − 9 contribuyeron de una forma importante a la compositión lipídica de los huevos. Mientras que el 20:5 n − 3 y el 22:6 n − 3 significaron un 4% y un 4,5% respectivamente de los lípidos totales del ovario que se aportaron a la puesta.