Arctic charr start-feeding with live artemia and preserved marine copepods: Effects on the onset of exogenous feeding, growth, and survival

Simple SummaryThe use of Artemia as a supplement to commercial feed during the nursery period, i.e., from post-larvae 10 up to post-larvae 30, is a common procedure in the shrimp industry. This practice provides larger and more resilient post-larvae (PL) that perform better in grow-out ponds. However, the production of brine shrimp is limited to a few natural salt lakes or man-made salt ponds worldwide, subject to strongly fluctuating yields and product quality. Therefore, ongoing research is focused on finding adequate live food alternatives. Nematodes, commonly known as worms, are animals that greatly fulfil the requirements to be used as live feed for aquatic organisms. Nematodes can be reactivated from their desiccated state by simple rehydration. Additionally, they are rich in protein and fatty acids, making them a favorable nutritional diet for shrimp larvae culture. This study demonstrated that nematodes can substitute Artemia in a co-feeding regime for the nursery of shrimp in a biofloc system, increasing the survival of the post-larvae after 20 days.This study evaluated nematodes as an alternative to live Artemia when provided in a co-feeding regime to Pacific white shrimp (Penaeus vannamei) post-larvae (PL) reared in a biofloc nursery system. A 20-day experiment employing PL11 was performed for an evaluation of four dietary groups: control [C] (fed exclusively with a dry commercial feed); artificial Artemia [AA] (dry feed composed of extracted and processed Artemia cysts and dry commercial feed); live Artemia and dry commercial feed [LA]; and nematodes and dry commercial feed [N] (Panagrolaimus sp. dry nematodes). The diets were provided twice a day, with the remaining six feed provisions being a commercial dry feed for all experimental groups. A biofloc system was chosen as it offers a potentially sustainable approach to intensive shrimp farming. Alkalinity and pH in the [N] group were significantly higher in the last 5 days of the experiment (p < 0.05), likely causing the significantly lower nitrite levels observed in that same group (p < 0.05). Total and volatile suspended solids were significantly lower in the two live feed groups when compared with [C] and [AA] (p < 0.05). Although PL fed the dry diets exhibited higher growth rates (p < 0.05), the [N] and [LA] groups presented significantly higher final survivals (p < 0.05). No differences were found for survival after a salinity stress test (p ≥ 0.05). These results suggest that nematodes can successfully substitute Artemia in a co-feeding regime for P. vannamei PL reared in biofloc nursery systems.

Current feeding protocols used in commercial hatcheries of Mediterranean fish species are, for a species-dependent period after hatching, based on live feeds which have often raised issues of biosecurity, stability, availability, price and nutrients content. Instead, dry feeds can offer stability in nutritional value, price and supply. The aim of the present study was to evaluate an alternative feeding protocol by co-feeding live and dry feed at first feeding red seabream larvae (on 3 days post-hatching—3 dph, DF3) and to compare it to a standard feeding protocol (i.e., dry feed introduced on 22 dph, DF22). Larvae productivity and functional development of the digestive system were evaluated under actual production conditions in a commercial hatchery. Additionally, post-larvae efficiency during pre-growing was evaluated under controlled laboratory conditions. The results obtained showed that the experimental protocol (DF3) promoted larval growth without affecting larval survival and the efficiency of the digestion processes. After pre-growing, DF3-produced juveniles showed a decreased incidence of spinal cord malformations, while the initially gained growth advantage was maintained. The present study shows the feasibility of an alternative feeding protocol for red seabream intensive larviculture and points out the critical role that larval rearing may have for later production stages.

Successful transition from endogenous yolk utilization to exogenous feeding is critical for survival in fish larvae, yet the changes in the brain during this transition remain incompletely described. In this study, whole-brain RNA sequencing was used to investigate transcriptomic changes over 48 h during endogenous yolk utilization (720 day degrees (dd)) and after the onset of exogenous feeding (920 dd) in Atlantic salmon (Salmo salar), focusing on appetite-related genes. Key components of appetite control, including melanocortin system and nutrient-sensing pathway, were present at 720 dd and elevated levels were observed at 920 dd. Before onset of first feeding, 16 appetite-related genes displayed a significant cyclic profile, where most had a periodicity of 20 h or 28 h. Following the transition from endogenous to exogenous feeding, the majority of significantly cyclic appetite-related genes exhibited a periodicity of 24 h, suggesting the establishment of circadian regulation associated with energy homeostasis. These results indicate that a pre-programmed expression of appetite and energy-related genes occurs in the brain before the yolk is fully utilized. Two weeks into the first feeding period (920 dd), the whole-brain transcriptome showed better responsiveness to feeding, but a fully developed satiety system remained underdeveloped. Additionally, characterization of hypothalamic melanocortin neuropeptides distribution during early salmon development revealed a spatial organization distinct from that reported in later life stages.

Simple SummaryLongfin smelt Spirinchus thaleichthys is an imperiled estuarine species in California, USA. A captive culture program is currently being developed; however, prior to this study, longfin smelt have only fed on live prey in the hatchery. Here, we report on our first successful attempt to wean cultured juveniles onto a dry commercial pellet feed. A subset of F1 fish was switched to a mixed diet of reduced Artemia and dry feed for 62 days, with growth, survival, and body condition compared between feeding treatments. Our results highlight that juvenile longfin smelt can utilize dry feeds while maintaining a healthy body condition.The rapid decline of longfin smelt Spirinchus thaleichthys, a threatened euryhaline forage fish in California, is a serious concern for scientists and resource managers. To recover and conserve this species, a captive culture program was initiated, focusing on the collection, captive rearing and breeding of wild broodstock, and the rearing of their offspring. Although progress has been made in the collection of broodstock and the production and culturing of larvae, no studies have evaluated the rearing of juvenile life stages in captivity. The present study examines methodological considerations for culturing F1 juvenile longfin smelt, specifically, the first efforts toward weaning juveniles to a dry commercial pellet feed. Cultured juvenile longfin smelt were fed live Artemia only or co-fed Artemia and dry feed for 62 days, and the effects of feed type on juvenile survival, growth, body condition, and fatty acid profiles were examined. No significant differences were observed between feeding treatments, despite an 80% reduction in Artemia in the co-feeding treatment. Furthermore, examination of fish stomach contents at the end of the trial confirmed the transition to dry feed. This is the first study to indicate successful feeding by longfin smelt on dry commercial pellets, and suggests that juvenile longfin smelt can be fully weaned onto dry feeds. Results of this study are critical for closing the lifecycle of longfin smelt in captivity and developing a successful conservation culture program for this imperiled species.

Growth of larval sharptooth catfish Clarias gariepinus fed live Artemia nauplii, a specially prepared dry feed (MN-3), a commercial dry salmon starter feed (Silver Cup 3600), or a combination of 50% live Artemia and 50% MN-3, under conditions of either light or dark for 21 days was studied. For all diets, fish reared in darkened tanks were significantly larger than those in illuminated tanks from day 8 onwards. Fish fed a combination of live Artemia plus MN-3 grew significantly more quickly than those fed either live Artemia or MN-3 only. On day 21 of the experiment, average weight of fish fed the combined diet was 649 ± 30 mg (mean ±SEM) in darkened tanks and 445 ± 16 mg in illuminated tanks, while those fed Artemia alone were 242 ± 9 and 198 ± 13 mg (dark and light, respectively) and fish fed MN-3 only were intermediate at 377 ± 20 and 267 ± 16 mg (dark and light, respectively). Catfish fed the salmon starter initially grew slowly, but after day 11 grew more quickly than the other groups. Mortalities were highest for fish fed salmon feed. Permanent darkness enhances the growth of C. gariepinus larvae during and after metamorphosis. While dry diets promoted higher growth rate than live Artemia nauplii alone, a combination of the two resulted in the fastest growth.

The intensive culture of characid teleosts for ornamental trade is highly dependent on live feed organisms, particularly Artemia nauplii, to provide nutrition through the larval stage. Live feeds have inherent disadvantages relative to prepared microparticulate diets (MDs), specifically availability, labor and cost. In this research, the dependence of larval Paracheirodon innesi on live Artemia was confirmed via a nutritional trial. Next, digestive system ontogeny was characterized from the onset of exogenous feeding through metamorphosis. P. innesi exhibited an agastric larval stage, as well as low digestive enzyme activity at the onset of exogenous feeding followed by abrupt increases in trypsin, lipase and pepsin activity. Differentiation of the stomach, including gastric gland formation and production of neutral mucopolysaccharides, as well as the onset of pepsin activity, did not occur until 20days post hatch (dph; 5.24 ± 0.20mm). This shift from agastric to gastric digestive modes is indicative of a proliferation of digestive capacity and subsequent prey diversity in other fish species exhibiting similar altricial larval stages.Based on this information, different schedules for weaning from Artemia to a MD were evaluated. For P. innesi fed until 32 dph, weaning beginning at 12 dph and 17 dph resulted in similar survival to live Artemia (mean: 22.0 ± 1.7%), and the MD resulted in the lowest survival (0.8 ± 0.3%). These results indicate that weaning is possible prior to gastric differentiation, potentially resulting in the reduction of Artemia use in the larval culture P. innesi.

Histological, histochemical and biochemical characterization of larval digestive system ontogeny in black tetra Gymnocorymbus ternetzi to inform aquaculture weaning protocols

Effect of pelleted diets with different pdcrotein levels on the growth and survival of the African bony-tongue (Heterotis niloticus) fry

Effect of Dry and Wet Feed on Growth Performance, Carcass Traits, and Apparent Nutrient Digestibility in Geese

Analysis of effects induced by a pollock protein hydrolysate on early development, innate immunity and the bacterial community structure of first feeding of Atlantic halibut ( Hippoglossus hippoglossus L.) larvae

Environmental conditions during early life can have a profound impact on developmental trajectory and ultimately ecological fitness of individuals. Therefore, from a conservation perspective it is vital to understand the longer-term implications of early phenotypic development on survival. In this study, we examined the effects of temperature (maintained at 16°C or ambient river temperature), prey condition (live or dead Artemia) and incubation method (tumbling jar or natural hatching over substrate) on the routine or standard metabolic rate (RMR, SMR), maximum metabolic rate (MMR), factorial aerobic scope, energy density (ED), whole body triglyceride concentration (TG), growth and mortality rate of age-0 lake sturgeon. Our results demonstrated that fish fed live artemia had significantly lower ED, growth and high mortality rates than those fed dead artemia at 32 days post-fertilisation (dpf) (p < .001). However, at 133 dpf fish fed live artemia showed higher MMR and no difference in ED, TG and growth rate compared to those fed dead prey during early life history. The present study showed that inclusion of live prey at the onset of exogenous feeding may be considered to promote a more natural phenotypic development in larval lake sturgeon.

This study was conducted to evaluate the efficacy of live food ( Artemia urmiana) and commercial diet in rearing of Oncorhynchus mykiss larvae. Experiment started when larvae were 0.12g in weight. Triplicate groups of fish were offered one of four treatments: (1) a commercial starter food; (2) live Artemia urmiana nauplii (for 3 days); (3) live Artemia urmiana nauplii (for 7 days); and (4) combination of live Artemia nauplii (5% of food) and the commercial starter food. They were fed four times daily starting at the onset of exogenous feeding, for 1 week. After 1 week, the fish of all groups were shifted to the commercial diet for an additional 3-weeks period to determine the impact of any differences in weight of fish. The result of the present study showed that those larvae fed with combination of Artemia nauplli and a commercial starter food grew significantly faster than other groups for 4 weeks. Larvae fed with other composition were similar in length and weight (P>0.05). Survival rates of the trout larvae ranged 86-96% after 1 week and 67-84% after 4 weeks. Larvae survival after 1 and 4 weeks were significantly higher (P<0.05) in trout larvae fed only on Artemia nauplii (treatments 2 and 3) than other treatments. The body chemical composition analysis of trout larvae showed only small differences, with the exception of the crude protein and lipid at 4 weeks. The data were analyzed to determine significant differences among treatments by one-way ANOVA. (Statistica v.9, StatSoft Inc.).

Intensive culture of lake whitefish ( Coregonus clupeaformis) from larvae to yearling size using dry feeds

Feeding Artemia to larvae of Atlantic halibut ( Hippoglossus hippoglossus L.) results in lower larval vitamin A content compared with feeding copepods

Objectives Larval fish of many species lack fully developed digestive systems at the start of feeding and thus require diets that accommodate their limited digestive capacity. Larval culture of Walleye Sander vitreus is often characterized by low survival and variable growth performance, and diets tailored for their specific requirements are not available. This study assessed the use of protein hydrolysates derived from muscle tissue of nonnative carp species (Hypophthalmichthys spp.) generated using digestive enzymes from adult Walleye. Methods Two feeding trials tested the relative performance of hydrolyzed and intact carp-derived proteins as first-feed diets (from first exogenous feeding at 4 d posthatch to 34 d posthatch) and as weaning diets (transitioning from live brine shrimp Artemia spp. nauplii at 22–44 d posthatch). Survival, growth performance, feed acceptance, swim bladder inflation, and deformity rate were monitored and compared amongst treatments. Results In the first-feeding trial, Walleye fed the hydrolysate diet had significantly improved growth performance relative to those fed the intact protein diet, but survival did not differ significantly among treatments. In the weaning trial, growth performance and survival did not differ between hydrolyzed and intact diets, but both diets supported better growth than feeds with marine-derived hydrolyzed proteins. The best growth performance in both trials was achieved with a currently available commercial starter diet. Conclusions The improved growth performance of the hydrolyzed diet in the first-feeding trial highlights the importance of providing diets suitable for the limited gut capacity of Walleye larvae in early development (prior to 22 d posthatch). Given the lack of differences in growth performance during the weaning trials, digestive capacity requirements appear less important in later larval development. Although proteins derived from nonnative carp hydrolyzed using same-species digestive enzymes show promise in Walleye larval culture diets, further refinement is needed to match the performance of currently available commercial diets. This study also presents a novel approach utilizing muscle from nonnative species and byproducts from processing plants in the form of fish digestive tracts.