Marine raw material choice, quality and weaning performance of Ballan wrasse (Labrus bergylta) larvae

Abstract

Previous results show that weaning success of Ballan wrasse larvae greatly depends on the quality of the dietary marine raw materials. In the present study, six moist or agglomerated experimental weaning diets containing different combinations of high-quality marine raw materials, being fish meal (FM), cod muscle meal (CMM), shrimp meal (SM) and krill hydrolysate (KH), were tested in a 2-month weaning trial with Ballan wrasse larvae of 34.5 mg initial body weight. Larvae performance was good in all dietary treatments except those fed diet D1 containing only FM. The Ballan wrasse larvae fed weaning diets D4 and D5 containing FM and either SM or KH, respectively, had the highest final body weight (0.7 g) but also the highest mortality (50%). Best weaning survival (77%) was obtained using the dry agglomerated diet D3 containing CMM and SM. During the first month, fish survival correlated positively with dietary free amino acid and soluble protein levels and negatively with the combined levels of dietary lipid oxidation metabolites and ethoxyquin. During the second month, mortality rates were lower in all treatments. Fish larvae final body weight correlated negatively with total dietary fatty acids and positively with dietary cholesterol, phosphorous and DHA/EPA ratio.

Essential fatty acid metabolism and requirements of the cleaner fish, ballan wrasse Labrus bergylta : Defining pathways of long-chain polyunsaturated fatty acid biosynthesis

“…Diet formulations for ballan wrasse have been developed based on those for other marine species such as Atlantic cod (Gadus morhua), with determination of nutrient requirements being mostly estimated by studying the biochemical composition of wild specimens (Hamre et al, 2013). While it was established that dietary DHA:EPA ratio positively correlated with growth performance (Kousoulaki et al, 2015), no studies identifying the EFA requirements for ballan wrasse have been published to date. Therefore, the results herein on the molecular and functional characterisation of two genes encoding key enzymes in the LC-PUFA biosynthetic pathways provide key insight into which EFA will require to be provided in diets for ballan wrasse.…”

“…Our findings thus suggest that DHA is technically not an essential fatty acid in ballan wrasse since it can be produced endogenously provided the diet contains EPA. However, it is likely that physiological demands for DHA in ballan wrasse exceed its biosynthetic capability, particularly in early life-cycle stages with rapidly forming neural tissues accumulating DHA (Monroig et al, 2009), and partly explaining why high dietary DHA:EPA positively correlated with growth performance of ballan wrasse juveniles (Kousoulaki et al, 2015).…”

“…As the demand for ballan wrasse juveniles grows, husbandry practices including feeding and nutrition (Hamre et al, 2013) for this species are rapidly developing in order to guarantee supply and avoid exploitation of wild populations. With regards to essential lipids, it has been reported that higher dietary DHA:EPA ratio is positively correlated with growth performance of ballan wrasse (Kousoulaki et al, 2015), but little is known about their capacity to utilise dietary VO to meet EFA requirements. For that purpose, the present study aimed to clone and functionally characterise fads2-and elovl5-like cDNAs with putative roles in the LC-PUFA biosynthetic pathways of ballan wrasse.…”

Intestinal Function of the Stomachless Fish, Ballan Wrasse (Labrus bergylta)

“…The pellets were 2 mm in diameter and sank slowly in seawater (density >1.024 g/cm 3 ). The diets were formulated based on information developed through a series of feeding studies (e.g., Kousoulaki et al, 2014Kousoulaki et al, , 2015Krogdahl et al, 2014;Bogevik et al, 2016), and were based on high quality marine raw materials (see Table 1). Two batches were made, one with yttrium the other with ytterbium as inert markers.…”

Influence of dietary n‐3 polyunsaturated fatty acids (PUFAs) on growth, PUFA composition and the expression of FAD6 and ELOV5 in pacific white shrimp ( Litopenaeus vannamei )

“…Long‐chain polyunsaturated fatty acids (LC‐PUFAs) of the n‐3 and n‐6 series, particularly eicosapentaenoic acid (C20:5 n‐3, EPA), docosahexaenoic acid (C22:6 n‐3, DHA) and arachidonic acid (C20:4 n‐6, ARA), have beneficial effects on immune responses, physiological processes and growth in aquatic animals (Chen et al., 2015; Kousoulaki et al., 2015). Growth in Litopenaeus vannamei increased with an increase in the dietary EPA and DHA content compared with animals fed a low n‐3 LC‐PUFAs diet (An et al., 2020; Araújo et al., 2019; Chen et al., 2015), but continue to increase dietary n‐3 LC‐PUFAs content did not further improve growth, and appeared to have a detrimental effect on survival of L.vannamei (An et al., 2020; González‐Félix et al., 2002).…”