Ryan L. Lane

Modification of Fillet Composition and Evidence of Differential Fatty Acid Turnover in Sunshine Bass Morone chrysops × M. saxatilis Following Change in Dietary Lipid Source

Marine oil-based finishing diets have been used to restore fillet FA profile in several “medium-fat” fleshed aquaculture species, and a simple dilution model describing FA turnover has been established to predict and tailor final fillet composition. We evaluated finishing diet efficacy and suitability of the dilution model to describe patterns of FA change in a lean-fleshed model, sunshine bass. Two practical diet (45% crude protein, 15% crude lipid) were formulated, respectively containing corn oil (CO) or menhaden oil (MO) as the primary lipid sources. Sunshine bass (age 1 [⊃ 14 mo], 347 ±8.6 g, mean individual weight ±SEM) were stocked in a recirculating system and fed the diets according to different feeding regimens during the final 28 wk of the production cycle. Control groups were fed the CO or the MO feeds exclusively; whereas, the remaining treatment groups were transitioned from the CO diet to the MO diet at 4−, 8−, or 12-wk intervals. Upon completion of the feeding trial, fish were harvested, and production performance and fillet composition were assessed. Replacing MO with CO as the primary lipid source in sunshine bass diets yielded fillets with distinctly different FA profiles; however, finishing with a MO-based diet offered significant compensation for CO-associated reductions in fillet long-chain highly unsaturated FA (LC-HUFA). Although complete restoration was not observed, we achieved significant augmentation of endogenous n−3 FA within 4 wk of feeding the MO diet, and observed a significant increase in LC-HUFA and a beneficial shift in n−3∶n−6 FA ratio after 8 weeks. Simple dilution accurately predicted tissue composition for most FA; however, deviations from the model were noted, suggesting selective retention of n−3, PUFA, and LC-HUFA and preferential catabolism of saturates. We conclude marine oil-based finishing diets can rapidly augment beneficial FA levels in sunshine bass fillets; however, simple dilution models do not fully describe selective FA metabolism observed for this lean-fleshed fish.

Influence of Dietary Replacement of Menhaden Oil with Canola Oil on Fatty Acid Composition of Sunshine Bass

Abstract The replacement of menhaden Brevoortia spp. oil with graded levels of canola oil in diets fed for 20 weeks to sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis) significantly impacted the fatty acid composition of fillets and livers. As the amount of canola oil increased from 0% to 100% of the oil in the diet, the amount of 18:1(n-9) and 18: 2(n-6) fatty acids in fillets increased linearly, whereas the amounts of 20:5(n-3), 22:6(n-3), long-chain n-3 highly unsaturated fatty acids (HUFAs), and total long-chain HUFAs in the fillets decreased linearly. Total long-chain n-3 HUFA levels did not differ significantly between fillets from fish fed a diet with 50% canola oil and those from fish fed 100% menhaden oil. The experimental diets also significantly altered the fatty acid compositions of the livers, though fatty acid levels were highly variable within and among treatments and differences usually were not as pronounced as differences in fillets. We observed no signi...

Effects of dietary lipid and fatty acids on white bass reproductive performance, egg hatchability, and overall quality of progeny

Abstract We evaluated the dietary effects of graded levels of highly unsaturated fatty acids (HUFAs) fed to broodstock female white bass Morone chrysops on reproductive performance, egg hatchability, and larval survival of sunshine bass (female white bass × male striped bass M. saxatilis) through the endogenous feeding stage. Dietary treatments consisted of four isocaloric, isonitrogenous diets formulated to contain 45% crude protein and 15% lipid with graded levels of menhaden oil (0, 25, 75, and 100%) or corn oil as the dietary lipid variable. Significant differences existed among the dietary groups in egg fatty acids, which reflected levels in the maternal diet, especially for the neutral lipid component. Similar trends were also found in fatty acids of the polar lipid component and conservation of HUFAs; significantly higher quantities of linoleic acid (18:2[n-6]) were associated with increasing dietary inclusion of corn oil. Eggs with higher hatchability were associated with higher levels of n-3 HUFA...

Zooplankton Size and Taxonomic Selectivity of Channel Catfish Fry

Abstract Zooplankton utilization and their importance to channel catfish Ictalurus punctatus fry during pond culture is not well documented. Current fry stocking decisions are based on total zooplankton densities. We studied the feeding habits (zooplankton size and taxa selection) of channel catfish fry. Catfish fry just completing swim-up were placed into glass aquaria or into cages in ponds and allowed to forage on natural zooplankton assemblages. The zooplankton sizes and taxa consumed by the fry were compared with the available sizes and taxa in the aquarium or pond environments. Rotifers and copepod nauplii were abundant in all environments but were never observed in the fry stomachs. Ostracods, adult copepods, and cladocerans were the only three taxa consumed. The data from both experiments indicated that ostracods were consumed in proportions equal to natural abundances, but in the field experiment larger ostracods were selected. Consumption of adult copepods and cladocerans depended on the relativ...

Influence of Organic Fertilizer Source on Fatty Acid Composition of Zooplankton and Sunshine Bass Fingerlings

Abstract We evaluated the influence of three organic fertilizers—cottonseed meal, ground rice bran, and ground flaxseed—on the fatty acid composition of zooplankton and fingerling sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). Flaxseed contains about 10-fold greater lipid and percent α-linolenic acid (18:3[n-3]); values relative to the other two organic fertilizers. Five 0.04-ha nursery ponds were randomly selected per treatment; 5 d before fish stocking (4 d posthatch; 150,000 fish/ha) and again at day 20 poststocking, ponds were individually fertilized at a rate of 350 kg/ha. After 27 d of culture, zooplankton in the flaxseed treatment contained significantly more 18:3(n-3) than those in the other fertilizer treatments (10.5% versus ∼7.0%). Likewise, after 40 d of culture, sunshine bass fingerlings reared in ponds fertilized with flaxseed possessed almost twofold higher 18:3(n-3) (10.7%) than those reared in rice bran (4.7%) and cottonseed (5.8%) treatment ponds. Fis...

Differential Incorporation of Dietary Fatty Acids from Flax and Fish Oils into Lipid Classes of White Bass Ova

Abstract The extent to which flax oil can replace fish oil in diets fed to female broodstock of white bass Morone chrysops was determined by evaluating growth performance and the fatty acid (FA) profile of ovum lipid classes. Four experimental diets containing increasing levels of flax oil as 0, 33, 67, and 100% replacement of menhaden (Brevoortia spp.) fish oil were fed to female white bass for 30 weeks prior to spawning. Overall, growth and survival were unaffected when flax oil replaced fish oil in the diets. However, ovum FA composition did differ by lipid class and according to dietary intake. The FA profile of the neutral lipid classes largely resembled dietary intake, resulting in monounsaturated FAs (MUFAs) and long-chain polyunsaturated FAs (LC-PUFAs; FAs with ≥20 carbons and ≥3 double bonds) as the most predominant FAs found within ova produced by 100% fish-oil-fed broodstock, while MUFAs and 18-carbon PUFAs dominated the ovum neutral lipid in females from the 100% flax oil treatment. Although t...

Significant Augmentation of Sunshine Bass Morone chrysops x M. saxatilis Fillet Highly Unsaturated Fatty Acid Content without Impact on Oxidative Stability or Sensory Attributes

We evaluated production performance, fillet composition, and sensory integrity of sunshine bass (Morone chrysops x M. saxatilis) fed a marine oil-based finishing feed after being raised on a plant oil-based production feed. Two feeds containing either corn oil (CO) or menhaden oil (MO) were fed to sunshine bass according to different feeding regimens at the close of the production cycle: control groups were fed the CO or the MO feeds exclusively; remaining groups were transitioned from the CO feed to the MO feed at 4-, 8- or 12-week intervals. Replacing MO with CO yielded fillets with distinctly different fatty acid profiles; however, finishing with an MO-based feed for 4–8 weeks offered significant compensation for reductions in fillet nutritional quality. Production performance and fillet sensory characteristics were largely unaffected by dietary lipid source, suggesting fillet fatty acid profile can be manipulated to maximize nutritional value of cultured fillets without reducing consumer acceptance.

Comparative Fatty Acid Composition of Eggs from White Bass Fed Live Food or Commercial Feed

Abstract We evaluated the influence of two broodstock feeding practices on fatty acid composition and viability of eggs in white bass Morone chrysops. The two dietary groups tested were (1) white bass females fed a commercially formulated feed (crude protein, 45%; crude fat, 16%) and (2) white bass females maintained on live food (fathead minnow Pimephales promelas and golden shiners Notemigonus crysoleucas). Significant differences existed between the dietary treatments in egg fatty acid levels. Eggs of white bass fed live food contained more 11-octadecenoic acid (18:1[n-7]), α-linolenic acid (18:3[n-3]), arachidonic acid (20:4[n-6]), docosahexaenoic acid (22:6[n-3]), and total n-3 fatty acids than eggs of fish fed formulated feed. Conversely, eggs of fish fed the formulated feed contained more oleic acid (18:1[n-9]), linoleic acid (18:2[n-6]), and total monoeic acids. Female white bass fed live food produced significantly more viable eggs (68.0 ± 2.0%) at 48 ± 2 h posthatch than did females fed the comm...