Hatchery Environment Research Articles

A large-scale, multi-year microbial community survey of a freshwater trout aquaculture facility.

Aquaculture is an important tool for solving the growing worldwide food demand, but infectious diseases of farmed animals represent a serious roadblock to continued industry growth. Therefore, it is essential to understand the microbial communities that reside within the built environments of aquaculture facilities to identify reservoirs of bacterial pathogens and potential correlations between commensal species and specific disease agents. Here, we present the results from 3 years of sampling a commercial rainbow trout aquaculture facility. We observed that the microbial communities residing on the abiotic surfaces within the hatchery were distinct from those residing on the surfaces at the facility's water source as well as the production raceways, despite similar communities in the water column at each location. Also, a subset of the water community seeds the biofilm communities. Lastly, we detected a common fish pathogen, Flavobacterium columnare, within the hatchery, including at the source water inlet. Importantly, the relative abundance of this pathogen was correlated with clinical disease. Our results characterized the microbial communities in an aquaculture facility, established that the hatchery environment contains a unique community composition and demonstrated that a specific fish pathogen resides within abiotic surface biofilms and is seeded from the natural water source.

Personality in hatchery Atlantic salmon (Salmo salar) is associated with growth but not metabolic rate or performance

The pace of life hypothesis (POLS) predicts that personality traits, like activity and boldness, are positively correlated with growth and metabolism. Here, we assess whether personality could predict body mass, metabolic rate, and performance under stress for hatchery-raised Atlantic salmon ( Salmo salar) 15 months post fertilization. Personality was evaluated for individual fish using a series of repeated trials alongside two stressful events (PIT tagging, simulated transport), to determine performance under stress. Standard metabolic rate (SMR) was then assessed via intermittent flow respirometry, and the relationships between personality, body mass, performance, and SMR were evaluated. Fish displayed repeatable behaviours, but not in accordance with POLS hypothesis. Smaller fish were more active and responsive to stimuli, while personality was not associated with SMR. Although smaller fish and fish with higher SMR both performed better under stress, body mass was unrelated to SMR. We discuss the utility of supporting the occurrence of a wider range of growth rates and body sizes in hatchery environments, as a means of promoting greater stress tolerance as well as faster growth.

Differences in External Morphology, Body Composition and Swimming Performance Between Hatchery- and Wild-Origin Marbled Rockfish (Sebastiscus marmoratus)

Stock enhancement based on hatchery-reared fish has become one of the most common forms of management practices in marine fisheries resource restoration. However, unnatural rearing environments may cause hatchery-reared fish to diverge phenotypically from wild conspecifics, with negative consequences for post-release performance in the natural environments. To better evaluate the suitability of releasing hatchery-reared fish, it is necessary to understand the phenotypic effects of captive rearing, through comparisons with wild conspecifics. In this study, we compared body morphology, swimming performance, and biochemical body composition between hatchery-reared and wild marbled rockfish (Sebastiscus marmoratus) from the same general gene pool. The results show that the overall body profile differed significantly between the groups, with hatchery-reared individuals having a deeper body (in particular in the head and trunk regions), narrower caudal peduncles, and higher condition factor, as compared to wild conspecifics. Hatchery-reared marbled rockfish also had relatively shorter fins, for a given size. In terms of swimming performance, the hatchery-reared marbled rockfish performed worse than the wild, with slower burst swimming speeds and poorer endurance. Wild rockfish had higher body protein content but lower lipid levels compared to the hatchery-reared individuals. These results suggest that hatchery rearing conditions have a great impact on the phenotypic development, with possibly high effects on their post-release performance of the hatchery-reared marbled rockfish. Modifications for the hatchery environment and operation should be investigated with an aim to minimize the divergence in phenotypic development for production of more wild-like fish for stocking.

Biogeography, succession, and origin of the chicken intestinal mycobiome

BackgroundExtensive work has been accomplished to characterize the intestinal bacterial community, known as the microbiota, and its association with host health and disease. However, very little is known about the spatiotemporal development and the origin of a minor intestinal fungal community, known as the mycobiota, in humans and animals, particularly in avian species.ResultsIn this study, we comprehensively characterized the biogeography and succession of the gastrointestinal (GI) mycobiota of broiler chickens and further revealed the fungal sources that are responsible for initial and long-term establishment of the mycobiota in the GI tract. Using Illumina sequencing of the internal transcribed spacer 2 (ITS2) region of fungal rRNA genes, we detected significant spatial and temporal differences in the mycobiota along the GI tract. In contrary to the microbiota, the mycobiota was more diverse in the upper than the lower GI tract with no apparent trend of succession up to 42 days of age. The intestinal mycobiota was dominated by the phyla Ascomycota and Basidiomycota with Gibberella, Aspergillus, and Candida being the most abundant genera. Although the chicken mycobiota was highly dynamic, Fusarium pseudonygamai was dominant throughout the GI tract regardless of age in this study. The core chicken mycobiome consisted of 26 fungal taxa accounting for greater than 85% of the fungal population in each GI location. However, we observed high variations of the intestinal mycobiota among different studies. We also showed that the total fungal population varied greatly from 1.0 × 104 to 1.1 × 106 /g digesta along the GI tract and only accounted for less than 0.06% of the bacteria in day-42 broilers. Finally, we revealed that the mycobiota from the hatchery environment was responsible for initial colonization in the GI tract of newly hatched chickens, but was quickly replaced by the fungi in the diet within 3 days.ConclusionsRelative to the intestinal microbiota that consists of trillions of bacteria in hundreds of different species and becomes relatively stabilized as animals age, the chicken intestinal mycobiota is a minor microbial community that is temporally dynamic with limited diversity and no obvious pattern of successive changes. However, similar to the microbiota, the chicken mycobiota is spatially different along the GI tract, although it is more diverse in the upper than the lower GI tract. Dietary fungi are the major source of the intestinal mycobiota in growing chickens.9xkijLeWQGnh2yA9yWZbikVideo abstract

Genetic Stock Identification and Adaptability of Hatchery-Reared Black Rockfish, Sebastes schlegelii, Released Into the North Yellow Sea waters

Successful stock enhancement refers to the maintenance of economic profit, whilst minimizing negative genetic and ecological effects. As hatchery environments differ from natural habitats, post-release identification of hatchery-reared juveniles, and estimation of their adaptability are essential steps in conducting responsible stock enhancement. The black rockfish is an important fishery species in Japan, South Korea and China. Overfishing has dramatically decreased natural resources and a stock enhancement program was first initiated in the Liaodong peninsula in 2019. We traced this program and used nine microsatellite markers to identify 279 individuals as being hatchery-reared, out of 710 captured fish, with a resource contribution rate of 39.30%. These results indicated that stock enhancement of this species is likely to maintain a positive economic performance. To understand the potential genetic impacts on the local wild population, the genetic patterns of S. schlegelii stocks (wild controls from 2017, wild controls from 2018, female broodstock from 2019, recaptured hatchery-reared fish from 2019 and recaptured non-hatchery-reared fish from 2019 stocks) from the same habitat were evaluated before and after artificial stocking. We found that the S. schlegelii population was able to maintain high genetic diversity and showed weak genetic differentiation, but potential genetic introgression derived from stock enhancement should be concerned. The hatchery-reared individuals showed good adaptability, as shown by feeding condition and growth status. There was no obvious morphology difference between hatchery-reared fish and their wild counterparts, but hatchery-reared fish seemed to be bigger in size (significantly higher in MDB and BW), had a larger head (significantly larger in PRL/HL and ID/HL) and smaller paired fins (significantly smaller PCFL/BL), when compared with wild individuals across all investigation months. Our results provided insights into management of black rockfish enhancement in the future.

Differences in brain morphology of brown trout across stream, lake, and hatchery environments.

It has been suggested that a trade‐off between cognitive capacity and developmental costs may drive brain size and morphology across fish species, but this pattern is less well explored at the intraspecific level. Physical habitat complexity has been proposed as a key selection pressure on cognitive capacity that shapes brain morphology of fishes. In this study, we compared brain morphology of brown trout, Salmo trutta, from stream, lake, and hatchery environments, which generally differ in physical complexity ranging from low habitat complexity in the hatchery to high habitat complexity in streams and intermediate complexity in lakes. We found that brain size, and the size of optic tectum and telencephalon differed across the three habitats, both being largest in lake fish with a tendency to be smaller in the stream compared to hatchery fish. Therefore, our findings do not support the hypothesis that in brown trout the volume of brain and its regions important for navigation and decision‐making increases in physically complex habitats. We suggest that the observed differences in brain size might be associated with diet quality and habitat‐specific behavioral adaptations rather than physical habitat complexity.

Using Age-0 Stocking to Assess Growth and Recruitment of Endangered Pallid Sturgeon Scaphirhynchus albus

(1) Assessing growth and recruitment can be difficult during early life history, especially for rare species such as the pallid sturgeon Scaphirhynchus albus (federally endangered in the United States). One potential tool to address this knowledge gap is the stocking of age-0 individuals. (2) During July 2018, two stocking events of marked age-0 pallid sturgeon (53–56 or 41–42 days old) occurred in the lower Missouri River resulting in the release of 8495 individuals. Over the following three years, pallid sturgeon were sampled with baited trotlines and benthic trawls during routine monitoring. (3) During this period, we captured 77 individuals that recruited to age 1 or older. Only 9% of captured individuals yielded length-at-age values falling below the 95% prediction interval for pallid sturgeon raised entirely in an energetically favorable hatchery environment with abundant food resources. (4) These results suggest that the lower Missouri River is capable of supporting hatchery-level growth for young pallid sturgeon. This study also provided a unique opportunity to document recruitment to age-1 of age-0 pallid sturgeon stocked at relatively small sizes, which highlights the potential benefits of utilizing stocking to address endangered species knowledge gaps.

Genomic signatures of adaptation to novel environments: hatchery and life history-associated loci in landlocked and anadromous Atlantic salmon (Salmo salar)

The adaptation of marine and anadromous fishes to novel, freshwater environments requires major physiological shifts in functions related to osmoregulation, immunity, and metabolism. For Atlantic salmon (Salmo salar) populations, such changes have occurred independently in many landlocked populations that were formed as a result of extensive hydrological shifts in North America around 10 000 years ago. We compared patterns of genetic variation between two landlocked and one anadromous population of Atlantic salmon to identify loci that may have played an important evolutionary role in facilitating the transition from an anadromous to an entirely freshwater life history. Outlier loci included single nucleotide polymorphisms (SNPs) in genes related to functions including immunity, growth, and osmoregulation. We also used these same populations to characterize loci associated with distinct hatchery rearing environments. This additional comparison identified outlier SNPs annotated to genes related to wound healing, consistent with findings from other genetic studies of domestication selection in fishes. Together, our results highlight putative responses to both natural selection imposed by major environmental changes and artificial selection levied by differing hatchery environments.

Offspring of first-generation hatchery steelhead trout (Oncorhynchus mykiss) grow faster in the hatchery than offspring of wild fish, but survive worse in the wild: Possible mechanisms for inadvertent domestication and fitness loss in hatchery salmon.

Salmonid fish raised in hatcheries often have lower fitness (number of returning adult offspring) than wild fish when both spawn in the wild. Body size at release from hatcheries is positively correlated with survival at sea. So one explanation for reduced fitness is that hatcheries inadvertently select for trait values that enhance growth rate under the unnatural environment of a hatchery, but that are maladaptive in the wild environment. A simple prediction of this hypothesis is that juveniles of hatchery origin should grow more quickly than fish of wild origin under hatchery conditions, but should have lower survival under wild conditions. We tested that hypothesis using multiple full sibling families of steelhead (Oncorhynchus mykiss) that were spawned using either two wild parents (WxW) or two first-generation hatchery (HxH) parents. Offspring from all the families were grown together under hatchery conditions and under semi-natural conditions in artificial streams. HxH families grew significantly faster in the hatchery, but had significantly lower survival in the streams. That we see this tradeoff after only a single generation of selection suggests that the traits involved are under very strong selection. We also considered one possible alteration to the hatchery environment that might reduce the intensity of selection among families in size at release. Here we tested whether reducing the fat content of hatchery feed would reduce the variance among families in body size. Although fish raised under a low-fat diet were slightly smaller, the variation among families in final size was unchanged. Thus, there is no evidence that reducing the fat content of hatchery feed would reduce the opportunity for selection among families on size at release.

Precocious Maturation of Hatchery‐Raised Spring Chinook Salmon as Age‐2 Minijacks Is Not Detectably Affected by Sire Age

AbstractJuvenile males produced in spring Chinook Salmon Oncorhynchus tshawytscha hatchery programs can exhibit high rates of maturation in freshwater as 2‐year‐old “minijacks.” This phenomenon is associated with high feeding rates and increased size and/or growth that juveniles experience in the hatchery environment, though studies also support a genetic component affecting age of maturation among salmonids, including precocious maturation in freshwater. This prompted a study to test whether the age of natural‐origin spring Chinook Salmon broodstock affects the rate at which their hatchery‐raised male progeny mature as age‐2 minijacks. In three consecutive brood years, we factorially mated age‐4 adult females with age‐3, age‐4, and age‐5 adult (jacks) male broodstock. In the latter two brood years, we also incorporated age‐1 precocious parr (microjacks) as sires. After communal rearing to the smolt stage (age 1), male juveniles were characterized as immature or as maturing minijacks based on plasma 11‐ketotestosterone concentration, and each was identified to its respective full‐sib progeny group via genetic parentage analysis. A generalized linear mixed model, performed for each brood year separately, was used to characterize expected precocious maturation rates by sire age, while controlling for potential effects of smolt body weight and individual parent identities. Multiple comparisons across sire ages within brood years were used to evaluate relative rates of precocious maturation. Estimates of the probability of minijack maturation among families within sire ages and brood years varied from as much as 0% to 100%, and no consistent effect of sire age on precocious maturation rate was observed. Exploratory analyses investigating additional effects of egg size, dam length, and spawn date also failed to identify consistent predictors of precocious maturation. Instead, variability was largely attributed to both dam‐ and sire‐specific effects, indicating a heritable component to precocious maturation, though not detectably associated with other measured attributes.

Skin and bone development in Atlantic salmon (Salmo salar) influenced by hatchery environment

Recirculating aquaculture systems (RAS) are receiving greater attention because they have potential to reduce the use of water, enable better control of environmental conditions and give greater biosecurity. However, little is known about the effects of conditions in RAS on early development. Here we compare the survival, development and gene expression of Atlantic salmon grown in a RAS and flow through (FT) system from egg until before they start to feed (at around 875°d). The epidermis of RAS fish was significantly thinner and contained larger numbers of mucosal cells, which were positioned more toward the skin surface, and less mineralisation of the vertebral body, than FT fish. Genes known to be involved in bone development and mineralisation were significantly up-regulated (inner ear specific collagen, transforming growth factor-beta-inducible early growth response protein 3 and salmon calcitonin) or down-regulated (metalloproteinase inhibitor 2-like, 25-hydroxyvitamin D3 1-alpha-hydroxylase and elongation of very long chain fatty acids protein 7-like) with RAS relative to FT treatment. Genes known to affect skin development, including keratin type I cytoskeletal 13-like and angiopoietin-related protein 7, were down-regulated in RAS compared to FT treated fish. Although no two RAS will share exactly the same environmental conditions, our comparison shows that early development of the skeleton and skin is hindered by the environment of the RAS used in this study and that a number of related genetic processes influencing skin and skeletal development are affected. These differences could affect the robustness of salmon at later life stages.

Isolation and antimicrobial resistance of motileSalmonella entericafrom the poultry hatchery environment.

Salmonella is a globally distributed major food-borne pathogen and poultry is one of the predominant sources of salmonellosis in humans. To investigate the presence of motile Salmonella in the poultry hatchery environment, we collected 97 fluff samples from four selected broiler breeder chicken hatcheries from Chattogram, Bangladesh during July-December 2015. To isolate motile Salmonella enterica, we used conventional bacteriological techniques followed by serological verification using anti-Salmonella Poly A-E serum and species confirmation by conventional PCR assay. Antimicrobial susceptibility testing by Kirby-Bauer disc diffusion method for 10 commonly used antibiotics was performed on all isolates. Isolates displaying phenotypic resistance to ampicillin were tested by PCR for blaTEM gene, whereas those resistant to tetracycline were tested for the presence of tetA, tetB and tetC genes. A total of 24 samples (24.7%; 95% CI: 16.5-34.5, N = 97) from 3 hatcheries were positive for motile Salmonella. Of them, 21 (87.5%) and 12 (50.0%) were resistant to ampicillin and tetracycline, respectively, 9 (37.5%) to nalidixic acid and sulphamethoxazole/trimethoprim. No resistance was detected to ceftriaxone, cefoxitin, gentamicin, neomycin, ciprofloxacin and colistin. Ten (42%) of 24 isolates from 2 hatcheries were multi-drug resistant (i.e. resistant to ≥ 3 antimicrobial classes). Six of 21 ampicillin resistant isolates contained blaTEM gene and 10 of 12 tetracycline resistant isolates contained tetA gene. This study highlights the circulation of multi-drug resistant motile Salmonella in the hatchery environment for the first time in Bangladesh. Further epidemiological and molecular studies are therefore needed to identify the serotypes and source of the bacteria in hatcheries.

Essential oil blend as a safe and effective disinfectant strategy for shrimp hatcheries

The Vibrio group of bacteria is considered highly pathogenic to shrimp larvae. Shrimp larvae are susceptible to Vibrio. It is difficult to eradicate Vibrio from the hatchery environment completely. Efforts were made to design an effective disinfectant with almost no side effects or residues. A formulation was developed by combining essential oils with antimicrobial properties to fight against pathogenic Vibrios, such as Vibrio harveyi and V. parahaemolyticus, in a hatchery environment. The anti-Vibrio formulation is a blend of Eucalyptus globulus, jasmine, and gardenia oils, designated as essential oil blend formulation (EOBF). The effective dose of EOBF was optimized on bacteria using TSA and on Vibrio using TCBS agar media. The optimized dose of 40 ppm EOBF was sprayed on the tank and culture area dry surfaces. The trial sites selected were the water filter tank, maturation tank, fry reservoir tank, quarantine and maturation tank, hatchery tank, spawning tank, rinsing tank, plankton tank, larvae rearing tank, packing tank, artemia tank, polychaetes (bucket and floor), squid (equipment and table), and freshwater tank of an experimental hatchery. The swab samples were collected after 3 hours, and a significant decrease in Vibrio, mostly green colonies, such as Vibrio harveyi and V. parahaemolyticus, was found after EOBF application. The obtained results showed that EOBF is an effective disinfectant against pathogenic Vibrios in shrimp hatcheries

Evaluation of the bactericidal effect of some disinfectants against E.coli and Salmonella isolated from poultry hatcheries

Poultry production considers one of the most important activities for economy and income in many countries . Proper management and hygiene in poultry hatchery mostly depend on efficient cleaning and sanitation of the hatchery environment and hatching eggs for production high quality newly hatched chicks . The aim of our study is to evaluate the effectiveness of some disinfectants (Aquavinol® 5%, Presept® 2.5%, Poviment® and MM8 ®) at various concentrations 1% , 1.5% and 2% at different contact times 30, 60, 90 and 120 minutes against E.coli and Salmonella which were isolated from the poultry hatcheries at a titer of 3×106/cm2. Our results showed that Aquavinol® 5% was the highest powerful disinfectant against these pathogens, followed by Presept® 2.5% and then Poviment® ,while MM8® was the weakest disinfectant at the same conditions. Our study concluded that the prevention & control of infections depend on the disinfectant of choice that must be applied with sufficient concentration at proper exposure time to achieve the best powerful effect on microorganisms with low costs.

Quantifying the effects of post-surgery recovery time on the migration dynamics and survival rates in the wild of acoustically tagged Atlantic Salmon Salmo salar smolts

BackgroundThe experimental effects of surgically implanting fish with acoustic transmitters are likely to have negative effects on survival and behaviour. Measuring the extent of these negative effects is important if we wish to extrapolate inferences from tagged animals to un-manipulated animals. In this study, we examine the effect of surgery and post-tagging recovery time on the survival and migration rate of acoustically tagged wild Atlantic Salmon (Salmo salar) smolts through freshwater, estuarine and ocean phases of migration. Four treatment groups were used: pre-smolt captured in the fall that overwintered in a hatchery and were tagged either 75 days prior to release (winter hatchery) or within 24 h prior to release (spring hatchery) and smolt captured during the spring smolt run, tagged 24 h prior to release and released during the day (day-released) or night (night-released).ResultsThe spring hatchery treatment group served as a reference treatment group such that recovery time (comparison to winter hatchery treatment) and hatchery effects (comparison to day-released and night-released treatments) could both be discerned. The hatchery effect increased migration rate, whereas short recovery times and captivity in a hatchery negatively affected survival. These effects were most pronounced within the first 5 days and/or 48 km downstream post-release, however, the residual recovery time effects appeared to persist during the transition from the estuary into salt water.ConclusionsEven with smolts originating from the wild and spending relatively little time within the hatchery environment, post-release survival was still negatively affected. Migration speed was faster for hatchery smolts, but is likely only due to their larger size. Recovery time effects were most prominent during the initial migration period in freshwater and again in the transition from the estuary to saltwater which may be due to added stress during these transitional zones. As surgery-related bias will likely never be completely removed from telemetry studies, it is important to quantify and account for these effects in situ when making inferences on the un-manipulated component of the population.

Efficacy of low-dose EarthTec® QZ treatment for the control of New Zealand mud snails Potamopyrgus antipodarum in a hatchery environment

Efficacy of low-dose EarthTec® QZ treatment for the control of New Zealand mud snails Potamopyrgus antipodarum in a hatchery environment

Does enriched rearing during early life affect sperm quality or skin colouration in the adult brown trout?

Enriched rearing has been demonstrated to shape the phenotype of hatchery-reared salmonids and improve their post-release survival in the wild, thus having an important applied value in conservation. However, it is unclear if rearing conditions or survival selection during the early life stages induce long-term fitness effects on adult phenotypes. Using a paired full-sib set-up, we investigated the influence of the environmental enrichment at the egg and fry stages on the milt quality and skin colouration of the adult brown trout (Salmo trutta L.). Overall, males had a higher number of skin spots than females. Notably, the total numbers of spots and black spots were significantly lower in fish raised in an enriched environment than in their full siblings reared in a conventional hatchery environment. However, neither sperm motility nor sperm swimming behaviour differed between full-sib males reared in different environments. Our results suggest that rearing method may shape the colouration of brown trout, either by ecological carry-over effects or by selective survival during the rearing process. This, in turn, indicates that ecological conditions at early life can have long-prevailing phenotypically plastic or microevolutionary effects on the adult traits of fish. These effects should be taken into consideration to better understand the ecological role of rearing methodology in salmonid conservation.

Assessment of PIT tag retention, growth and post-tagging survival in juvenile lumpfish, Cyclopterus lumpus

BackgroundPassive integrated transponder (PIT) tags are used to study the movement and behaviour in populations of a wide variety of fish species and for a number of different applications from fisheries to aquaculture. Before embarking on long-term studies, it is important to collect information on both short- and medium-term survival and tag retention for the species in question. In this study, 90 juvenile lumpfish (10–20 g, 30 fish per replicate tank) were implanted with 12.5-mm FDX PIT tags.ResultsTag retention, growth rates and survival were compared to those of fish subjected to handling only (90 fish, 30 per replicate tank). Overall survival was 100% during the 28-day monitoring period, and tag retention was 99%.ConclusionsResults indicate that retention rates of 12.5-mm PIT tags in juvenile lumpfish are high, and there is no significant effect on growth rates or survival in a hatchery environment.

Composition and Function of Chicken Gut Microbiota.

Simple SummaryChickens evolved for millions of years to be hatched in a nest in contact with an adult hen. However, current commercial production of chickens is based on hatching chicks in a clean hatchery environment in the absence of adult hens. The ancestors of domestic chickens inhabited a living environment different from that used for current commercial production. Currently, the lifespan of broilers is around 5 weeks, the lifespan of egg layers is around one year while chickens can live for 15–20 years. This means that studies on chicken–microbiota interactions are of specific importance. The intestinal tract of commercially hatched chicks is gradually colonised from environmental sources only, however, if the chicks are provided experimentally with microbiota from a hen they can be colonised by adult-type microbiota from the very first days of life and become resistant to infections with pathogenic Escherichia coli, Clostridium perfringens, or Salmonella. Because of such specificities in the interactions of chickens with their gut microbiota, current knowledge in this area is critically presented in this review.Studies analyzing the composition of gut microbiota are quite common at present, mainly due to the rapid development of DNA sequencing technologies within the last decade. This is valid also for chickens and their gut microbiota. However, chickens represent a specific model for host–microbiota interactions since contact between parents and offspring has been completely interrupted in domesticated chickens. Nearly all studies describe microbiota of chicks from hatcheries and these chickens are considered as references and controls. In reality, such chickens represent an extreme experimental group since control chicks should be, by nature, hatched in nests in contact with the parent hen. Not properly realising this fact and utilising only 16S rRNA sequencing results means that many conclusions are of questionable biological relevance. The specifics of chicken-related gut microbiota are therefore stressed in this review together with current knowledge of the biological role of selected microbiota members. These microbiota members are then evaluated for their intended use as a form of next-generation probiotics.

Genotype by environment interaction for shell length in Mytilus galloprovincialis

Several drawbacks have emerged on the welfare status of shellfishes grown intensively in natural estuaries, such as density-dependent competition, overexploitation, low growth, and harmful algae blooming episodes (HAB), which anticipate profound socioeconomic consequences. The improvement of body size would hitchhike other growth surrogates and is a natural solution to increase productivity and circumvent HAB by shortening the production cycle. Such improvement in aquaculture depends on the existence of genotypic variation in quantitative traits. Namely, heritability plays a predictive role in the study of metric characters because it measures the resemblance between the phenotypic value and the breeding value. The aim of this study was to estimate variance components and interaction phenomena on shell length of the quasi-sessile marine invertebrate M. galloprovincialis grown in a Hatchery Environment Nucleus (HEN) and replicated in a Production Environment (PDE). A large amount of additive variation for shell length exists in M. galloprovincialis which broad-sense heritability after the animal model was higher in the richer production environment (h¯2AM_PDE = 0.643 ± 0.066) than in the hatchery environment (h¯2AM_HEN = 0.606 ± 0.127). The stability of the phenotypic variation (Vp) observed in HEN, suggests the increasing weight of the non-additive genetic variance which makes h2 increase with age. The reaction norm showed a reduced phenotypic variance in PDE as a byproduct of a change in scale as well as in ranking due to the presence of Genetic by Environment Interaction (GEI). Therefore, quantitative parameters recorded in the farm (HEN) should not be employed to extrapolate potential growth in the production field (PDE). Provided that selection accuracy depends on both, Family by Environment Interaction (FEI) and GEI, evaluation in the breeding nucleus entailed a global 5.35% gain overestimation (∆G= + 3.74 mm in shell length) on the expected phenotypic gain in PDE of the directional L lines constructed. Correction for accuracy and genetic correlation indicates that a selective breeding program for directional selection could yield a 9% (6 mm in shell length) gain in the first generation at PDE what could allow to attain a significant production cycle shortening in few generations of selection.