Post Hatch Research Articles

Influence of environmental enrichment on circulating white blood cell counts and behavior of female turkeys

Under commercial conditions turkeys are housed in large groups in poorly structured environments. This leads to stress and subsequently to pecking and cannibalism. Environmental enrichment is suggested to reduce stress and feather pecking, thus leading to an increase of the overall flock health. However, the effect of increasing age on the use of enrichment elements and on the behavior repertoire as well as its correlation with health parameters has scarcely been studied. Therefore, our objective was to investigate the influence of environmental enrichment on the behavioral repertoire and on health parameters of turkeys. In 3 consecutive trials, female turkeys were housed up to 12 wk either in an unstructured (control group) or enriched environment (EE group) featuring elevated plateaus at different levels (“turkey tree”). Behavior parameters, clinical health, and immune parameters were determined at selected time points. The percentage of birds using the turkey tree increased with age up to 55 to 77% at 22 to 30 d post hatch (dph). Thereafter, the number of birds located on the turkey tree decreased to 25 to 32% at 73 to 79 dph. Feather pecking and fighting was significantly lower in the EE group compared to the control group in 2 and 3 trials, respectively (P < 0.05). The integrity of feathers and integument, scored in the head/neck, wing, and tail regions was repeatedly better in the EE birds compared to control birds at most investigated time points (P < 0.05), suggesting a reduction in stress related aggression by the use of the turkey tree. Head pecking, running and flying activity, foraging, and preening were overall comparable between the EE and the control group (P > 0.05). Humoral immunity as determined by vaccination-induced anti-Newcastle disease virus antibody titers was not affected by the turkey tree use. The flow cytometric evaluation of blood monocyte and T-lymphocyte numbers showed no repeatable difference between control and EE groups. Interestingly, compared to the control groups, EE birds displayed significantly higher numbers of circulating MHC class II+ lymphocytes and lower numbers of thrombocytes at various time points compared to controls (P < 0.05). This study provides clear evidence that environmental enrichment with plateaus not only leads to an altered behavioral repertoire but also modifies some of the investigated immune parameters, implying that EE may have a modulatory effect on turkeys’ immunity and overall fitness. Further studies are needed to understand the correlation between behavior and health parameters in birds more closely.

Expression of long-chain polyunsaturated fatty acids biosynthesis genes during the early life-cycle stages of the tropical gar Atractosteus tropicus.

Long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA), including eicosapentaenoic acid (EPA, 20:5n-3), arachidonic acid (ARA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3), are essential in multiple physiological processes, especially during early development of vertebrates. LC-PUFA biosynthesis is achieved by two key families of enzymes, fatty acyl desaturases (Fads) and elongation of very long-chain fatty acid (Elovl). The present study determined the expression patterns of genes encoding desaturases (fads1 and fads2) and elongases (elovl2 and elovl5) involved in the LC-PUFA biosynthesis during early life-stages of the tropical gar Atractosteus tropicus. We further analyzed the fatty acid profiles during early development of A. tropicus to evaluate the impact of Fads and Elovl enzymatic activities. Specific oligonucleotides were designed from A. tropicus transcriptome to perform qPCR (quantitative polymerase chain reaction) on embryonic and larval stages, along with several organs (intestine, white muscle, brain, liver, heart, mesenteric adipose, kidney, gill, swim bladder, stomach, and spleen) collected from juvenile specimens. Fatty acid content of feeds and embryonic and larval stages were analyzed. Results show that fads1, fads2, elovl2 and elovl5 expression was detected from embryonic stages with expression peaks from day 15 post hatching, which could be related to transcriptional and dietary factors. Moreover, fads1, fads2 and elovl2 showed a higher expression in intestine, while elovl5 showed a higher expression in liver, suggesting that the tropical gar activates its LC-PUFA biosynthetic machinery to produce ARA, EPA and DHA to satisfy physiological demands at crucial developmental milestones during early development.

Effects of Monochromatic Lighting During Incubation and Vaccination on the Splenic Transcriptome Profiles of Chicken.

Lighting is a crucial environmental variable in poultry operations, but illumination during incubation is relatively understudied. The ability to stimulate development or immune performance using in ovo lighting is a promising approach for improving poultry health and welfare. This study investigated how monochromatic green light during incubation and vaccination method and timing affected chicken splenic gene expression patterns. We performed this study with 1,728 Hy-Line white layer eggs incubated under two light treatments during incubation: continuous dark and continuous green monochromatic light, over the entire incubation period. Half the eggs in each light treatment received in ovo vaccination, applied on embryonic day 18 (ED18). The remaining half were vaccinated by spraying on hatch day. After hatching, the light treatments followed the industry-standard lighting regimens. The study had six treatment groups with light–dark pairs for non-vaccinated, in ovo vaccinated, and post-hatch vaccinated. We assessed splenic gene expression at ED18 and at 7 days post-hatch (PH) in all the treatments. We isolated and sequenced 24 mRNA libraries on the Illumina platform, followed by bioinformatics and differential gene expression analyses. RNAseq analysis showed between 62 and 6,755 differentially expressed genes (DEGs) between comparisons, with the most prominent differences observed between ED and PH samples, followed by comparisons between vaccination methods. In contrast, light vs. dark treatments at ED showed limited effects on transcriptomic profiles. However, we observed a synergistic effect of lighting during incubation on post-hatch vaccination responses, with differentially expressed genes (DEGs) unique to the light treatment showing stimulation of cell proliferation with significance for immune activity (inferred from gene ontology terms). Gene ontology and pathway analysis indicated biological processes like cellular component organization or biogenesis, rhythmic process, developmental process, response to stimulus, and immune system processes were explained by the DEGs. While lighting is an important source of circadian stimulation, other controlled studies are required to clarify whether in ovo circadian entrainment plays a role in modulating immune responses.

The effect of delayed feeding post-hatch on caeca development in broiler chickens

ABSTRACT 1. Broiler chicks are frequently deprived of food up to 72 h due to uneven hatching rates, management procedures and transportation to farms. Little is known about the effect of delayed feeding due to extended hatching times on the early neonatal development of the caeca. Therefore, the objective of this study was to investigate the developmental changes and effects of a 48-h delay in feed access immediately post-hatch (PH) on the caeca. 2. After hatch, birds (Ross 708) were randomly divided into two treatment groups (n = 6 battery pen/treatment). One group (early fed; EF) received feed and water immediately after hatch, while the second group (late fed; LF) had access to water but had delayed access to feed for 48 h. Contents averaging across all regions of the caeca were collected for mRNA expression as well as for histological analysis at −48, 0, 4 h PH and then at 1, 2, 3, 4, 6, 8, 10, 12 and 14 days PH. 3. Expression of MCT-1 (a nutrient transporter), Cox7A2 (related to mitochondrial function) IgA, pIgR, and ChIL-8 (immune function) genes was affected by delayed access to feed that was dependent by the time PH. Expression of immune and gut barrier function-related genes (LEAP2 and MUC2, respectively) was increased in LF group. There was no effect of feed delay on expression of genes related to mitochondrial functions in the caeca, although developmental changes were observed (ATP5F1B, Cox4|1). Caecal mucus and muscle thickness were affected by delayed access to feed during caeca development. 4. The data suggested a limited effect of delayed feed access PH on the developmental changes in caecal functions. However, the caeca seemed to be relatively resistant to delayed access to feed early PH, with only a few genes affected.

Energy and phosphorus evaluation of poultry meal fed to broiler chickens using a regression method

Two experiments were conducted to determine energy (Exp. 1) and P (Exp. 2) utilization in poultry meal (PM) for broiler chickens. A total of 192 birds were allotted to 3 experimental diets in a randomized complete block design with BW as a blocking factor on d 15 and 16 post hatching in Exp. 1 and 2, respectively. Each diet was fed to 8 replicate cages with 8 birds per cage in both experiments. Initial BW of birds in Exp. 1 and 2 were 438 ± 76.9 g and 543 ± 50.2 g, respectively. Three corn-soybean meal-based diets were prepared to contain 0, 80, or 160 g/kg in Exp. 1 and 0, 50, or 100 g/kg in Exp. 2. In Exp. 1, the addition of PM to the reference diet linearly decreased (P < 0.01) the apparent ileal digestibility of DM and gross energy (GE), as well as the apparent total tract utilization (ATTU) of DM, GE, and N in diets; but did not affect the ileal digestible energy, ME, and MEn of diets. The ileal digestible energy, ME, and MEn of PM estimated by the regression method were 4,002, 3,756, and 3,430 kcal/kg DM, respectively, representing 58 to 68% of the GE in PM. In Exp. 2, graded concentration of PM in the reference diet linearly decreased (P < 0.05) ATTU of DM but linearly increased (P < 0.01) ATTU of P and quadratically increased ATTU of Ca in diets. The true ileal digestibility and true total tract utilization of P in PM estimated by the regression method were 77.5 and 79.0%, respectively. In conclusion, these results showed that inclusion of poultry meal in the diets of broiler chickens reduced the digestibility of GE but increased the utilization of P. The regression-estimated energy values and P digestibility of PM in the current studies may be used in diet formulation.

EFFECT OF DIFFERENT ADMINISTRATION METHODS OF VITAMIN AD3E TO HATCHING EGGS AND SUPPLEMENT IT WITH DRINKING WATER ON HATCHABILITY TRAITS AND POST HATCH PERFORMANCE AND BIOCHEMICAL PARAMETER OF BROILER

This study was conducted at the Badi Hatchery and poultry house / department of animal production / College of Agriculture engineering science/ University of Duhok. The aim of study was to investigate the effect of different administration methods of vitamin AD3E to hatching eggs on hatchability and post hatch productive performance and some physiological parameter of broiler. A total of one thousand and two hundred fifty (1250) hatched eggs were distributed into five groups each groups 250 eggs. The experimental treatments were as the follow: T1 (Control), T2 (sham control)(injected with 0.1 ml normal saline), T3 (injected with 0.1 ml of vitamin AD3E dissolved in 5 ml of vitamin in 1 ml of water) T4 (Spraying vitamin AD3E 1 ml /L water), T5 (Dipping vitamin AD3E 1 ml /L water). During the rearing period, each treatment divided into 2 group of replications, (5 replication) for each group that is from one treatment exactly. First 5 five replications (R1-R5) for each treatment given different doses of vitamin at different rearing age via drinking water and other 5 five replications (R6-R10) were drink normal water throughout the rearing period which is at least 5 weeks. Weekly Live body weight, body weight gain, feed consumption, feed conversion ratio, mortality percentage, Production index were recorded, (Total protein, glucose and cholesterol), blood serum titer for testing the immunity of chicken against diseases Newcastle (ND) and Gumboro, infectious bronchitis (IB). The overall data shows the following results: - In hatching stage there were significant affect in chick weight and chick to egg ratio and in rearing stage live body weight, body weight gain, feed conversion ratio, production index, serum glucose, Newcastle Gambaro and infectious bronchitis disease.

Changes in gill and air-breathing organ characteristics during the transition from water- to air-breathing in juvenile Arapaima gigas.

The obligate air-breathing Amazonian fish, Arapaima gigas, hatch as water-breathing larvae but with development, they modify their swim bladder to an air-breathing organ (ABO) while reducing their gill filaments to avoid oxygen loss. Here, we show that significant changes already take place between 4 weeks (1.6 g) and 11 weeks (5 g) post hatch, with a reduction in gill lamellar surface area, increase in gill diffusion distance, and proliferation of the parenchyma in the ABO. By using a variety of methods, we quantified the surface area and diffusion distances of the gills and skin, and the swim bladder volume and anatomical complexity from hatch to 11-week-old juveniles. In addition, we identified the presence of two ionocyte types in the gills and show how these change with development. Until 1.6 g, A. gigas possess only the H+ -excreting/Na+ -absorbing type, while 5-g fish and adults have an additional ionocyte which likely absorbs H+ and Cl- and excretes HCO3- . The ionocyte density on the gill filaments increased with age and is likely a compensatory mechanism for maintaining ion transport while reducing gill surface area. In the transition from water- to air-breathing, A. gigas likely employs a trimodal respiration utilizing gills, skin, and ABO and thus avoid a respiratory-ion regulatory compromise at the gills.

EFFECT OF IN OVO INJECTION OF 25 HYDROXYCHOLECALCIFEROL DURING EMBRYONIC DEVELOPMENT ON BROILERS PERFORMANCE, BONE STRUCTURE AND SOME BLOOD PARAMETERS

This study was conducted to investigate the effect of in ovo injection of vitamin D3 during different embryogenesis periods on post hatch productive performance, some blood parameters, bone growth and jejunum and tibia bone histology of Hubbard chicks. A total number of 500 eggs with average weight of 65 g were obtained from a commercial broiler breeder flock (Hubbard) at 55 weeks of age. Eggs were divided into five groups of 100 eggs in four replicates, 25 eggs each. The first one was served as negative control group (un-injected), while the second and third groups were used as sham control which were injected with (0.1 ml sterile wateregg) into air cell at day 7and 14, respectively (SE7, SE14). The Fourth and Fifth groups were injected with a dose of 0.1 ml vit.D3 (Containing 500 IU) into air cell at day 7 and 14 of incubation period respectively (DE7, DE14). The present findings revealed that chicks hatched from eggs injected with vit. D3 has significantly better productive performance (higher LBW and BWG, less FI and better FCR) than control and sham groups. Plasma level of PTH, Ca, P, ALK-P and ACP were significantly increased with in ovo injection with vit. D3. Also, Tibia weight, length and width were significantly increased for the in ovo injected with vit.D3. Femur weight, length and width were insignificantly increased for the in ovo injection with vit.D3. Shank length was significantly increased for the in ovo injection with vit.D3, while shank width was insignificantly increased compared with the control and sham groups. Furthermore, the histological structure of bone was enhanced with in ovo injection with vit. D3 either at 7 or 14 days of incubation period. In conclusion from the present study shows that in ovo injection with a dose of 0.1 ml vit.D3 (Containing 500 IU) in Hubbard broiler chicks at 7th or 14th day of incubation period enhanced productive performance, blood parameters, bone development and histological structure.

The spleen of Sonali chicken: morphohistology and biometric analysis at post hatching ages

Although Sonali chicken is introduced to the poultry industry of Bangladesh during 1999-2000 and after that playing a pivotal role in national economy, no literature is available regarding histomorphometry of spleen of Sonali chicken. As spleen is a key component of chicken’s defense mechanism, the study was designed to investigate the age related development of spleen of Sonali chicken, i.e, morphohistology and biometry at several postnatal stages. The investigation was carried out on 25 healthy Sonali chickens representing different ages at after hacting days 1, 14, 28, 42, and 56 (n=5). After ethically sacrifice (cervical subluxation method), spleen was collected and subjected for both macro and microscopic examinations. Haematoxylin and Eosin stain was done for the later. Morphologically, spleen was found lying dorsally at the right side of the abdominal cavity. It was oval or rounded organ, reddish brown in color. The gross morphometric observations (average weight, organ index, length, width and thickness) found significantly increasing throughout the tenure (p&lt;0.001). In microscopic study, no trabeculae and identifying marginal zone was recorded in the splenic parenchyma of Sonali chicken. And a component of white pulp (lymphatic nodules) appeared at day 14 onward. This study gives an insight about the age correlated development of spleen of Sonali chicken at different age intervals which advance our knowledge and leads an array for further immunization researches about immunological activities and molecular detection of spleen, which would be impossible without learning the basic anatomy.&#x0D; Asian J. Med. Biol. Res. March 2021, 7(1): 69-75

Beta alanine effects immediately pre- and post hatch on chick quality, carcass yield and meat quality in broilers

First, this study aimed to evaluate the effects on hatchability of in ovo supplementation of beta alanine (βA). Second, it assessed the effects on performance, meat quality and serum constituents of broiler chickens of βA injection in ovo and of supplementation with βA in feed for the first seven days after hatching. For this purpose, 960 fertilized broiler chicken eggs were distributed to hatchery trays in four treatment groups with six replicates on day 17 of incubation. The treatment groups consisted of eggs that were not injected (T1; negative control), injected with sterile solution with 0.9% salt (T2; positive control), injected with in ovo 1% βA solution (T3), and not injected, but with chicks were fed 1% βA for the first seven days after hatching (T4). Upon hatching, chicks from T1, T2, and T3 were fed commercial starter feed. All treatments were assessed with six replicates of 28 birds (14 females and 14 males) throughout the grow-out period. As a result of this study, T3 increased hatchability, yolk-free hatching weight and chick quality, and decreased yolk weight and feed access time at hatch. Both T3 and T4 improved carcass yield and meat quality, and T3 increased serum total antioxidant status at 42 days afer hatching. The results demonstrated that in ovo βA feeding improved hatching characteristics, and βA administration in ovo or in feed improved carcass yield and meat quality without affecting growth performance.

True phosphorus digestibility of cottonseed meal and rice husk supplemented with microbial phytase in broiler chickens

This research aimed to determine effects of phytase in cottonseed meal (CM) and rice husk (RH) based diets on true phosphorus digestibility (TPD) by broiler chickens. Two studies were conducted with 576 one-day-old broiler chickens using regression analysis to determine the TPD in these diets and the response to phytase supplementation. Six semi-purified diets were formulated to contain 150 g, 300 g, and 450 g each of CM/kg (experiment 1) and RH/kg (experiment 2) with phytase supplied at 0 and 1000 units/kg. Titanium dioxide was added to the diets at the rate of 5 g/kg as an indigestible maker. A total of 288 broiler chickens in each study were weighed and allotted to the six diets with six replicates of eight birds in a randomized complete block design. The birds were fed the experimental diets until day 26 post hatch. The coefficients of true phosphorus retention (TPR) were 0.8 for CM and 0.78 for RH without phytase; 0.93 for CM and 0.92 for RH with phytase. True phosphorus digestibility was 0.82 for CM and 0.75 for RH without phytase; and 0.95 for CM and 0.92 for RH with phytase. Phytase supplementation resulted in 13.27 and 17.94 % increases in TPD; and 12.29 and 13.61 % increases in TPR by birds fed the CM and RH diets, respectively. Phytase supplementation of CM and RH based diets increased TPD and improved total TPR and true ileal phosphorus digestibility in broiler chickens.

Induced breeding and larval rearing of vermiculated spinefoot, Siganus vermiculatus (Valenciennes, 1835) in indoor conditions

Vermiculated spinefoot, Siganus vermiculatus has been reported to be one of the fastest growing species among genus Siganus. Even though it breeds in captivity, commercial level hatchery production is yet to be achieved. In the present study, mature brooders of S. vermiculatus (female weighing 400 g and male weighing 385 g) were induced to breed in captivity and the larvae were reared to metamorphosis. Fishes (55 nos., 150 g–700 g) were collected from the wild and reared in marine cages using formulated floating pellets as feed. Among the mature fishes brought to the hatchery, a female having an average ova diameter of 440 μm and a running male were induced with two intramuscular injections of human chorionic gonadotropin (hCG) at the rate of 500 IU/ fish and 200 IU/ fish respectively in a spawning tank. Spawning occurred on the day after the full moon, between 20- and 21 h after the second injection. Fecundity was estimated as 1.85 lakhs with 68–71% of viable eggs and hatching rate of 73–85%. Green water systems with microalgae, Nannochloropsis salina and Isochrysis galbana at a concentration of 2–3 × 106 cells mL−1 and 2–3 × 105 cells mL−1 were used in tanks (1000L) for egg incubation and larval rearing respectively. Copepod, Parvocalanus crassirostris (T1) and enriched rotifer, Brachionus rotundiformis (S-type) (T2) were tested as first feed for newly hatched larvae. The fertilised eggs (0.57 ± 0.02 mm) hatched out between 24 and 25 h and the newly hatched larvae measured 1.92 ± 0.08 mm in total length with a transparent yolk sac (0.63 ± 0.04 mm) and an oil globule (0.23 ± 0.02 mm). Mouth gape of 89.03 ± 9.4 μm was observed after 42 h post hatch. The use of copepod, P. crassirostris as the first feed helped in successful rearing of the larvae to metamorphosis and an improved survival rate (4.5%–12%). Metamorphosis was completed within 35–37 dph, during which post larvae with vermiculated body pattern measured 25.2–28.4 mm in length and 0.28–0.30 g in weight. Enriched rotifers (5–37 dph), copepodites (10–20 dph), umbrella stage of Artemia (18–24 dph), artificial pellet feeds (21–37 dph) and enriched Artemia nauplii (29–37 dph) were also used during various stages of larviculture. The present study is the first report of induced breeding of S. vermiculatus during full moon phase of lunar cycle. The results of the present study also demonstrate a protocol for successful rearing of larvae to metamorphosis with P. crassirostris nauplii as first feed.

The effect of multi-strain probiotics as feed additives on performance, immunity, expression of nutrient transporter genes and gut morphometry in broiler chickens.

ObjectiveThis study was conducted to investigate the effects of dietary multi-strain probiotic (MSP) (Bacillus coagulans Unique IS2 + Bacillus subtillis UBBS14 + Saccharomyces boulardii Unique 28) on performance, gut morphology and expression of nutrient transporter related genes in broiler chickens.MethodsA total of 256 (4×8×8) day-old CARIBRO Vishal commercial broiler chicks of uniform body weight were randomly distributed into four treatments with 8 replicates each and having eight chicks in each replicate. Four dietary treatments were T1 (negative control-basal diet), T2 (positive control-antibiotic bacitracin methylene disalicylate at 20 mg/kg diet), T3 (MSP at 107 colony-forming unit [CFU]/g feed), and T4 (MSP at 108 CFU/g feed).ResultsDuring 3 to 6 weeks and 0 to 6 weeks, the body weight gain increased significantly (p<0.05) in T3 and T4 groups. The feed intake significantly (p<0.05) reduced from T1 to T3 during 0 to 3 weeks and the feed conversion ratio also significantly (p<0.05) improved in T3 and T4 during 0 to 6 weeks. The humoral and cell mediated immune response and the weight of immune organs were also significantly (p<0.05) improved in T3 and T4. However, significant (p<0.05) dietary effects were observed on intestinal histo-morphometry of ileum in T3 followed by T4 and T2. At 14 d post hatch, the relative gene expression of glucose transporter (GLUT5), sodium-dependent glucose transporter (SGLT1) and peptide transporter (PepT1) showed a significant (p<0.05) up-regulating pattern in T2, T3, and T4. Whereas, at 21 d post hatch, the gene expression of SGLT1 and PepT1 was significantly (p<0.05) down-regulated in MSP supplemented treatments T3 and T4.ConclusionThe supplementation of MSP at 107 CFU/g diet showed significant effects with improved performance, immune response, gut morphology and expression of nutrient transporter genes. Thus, the MSP could be a suitable alternative to antibiotic growth promoters in chicken diets.

Arterial wall thickening normalizes arterial wall tension with growth in American alligators, Alligator mississippiensis.

Arterial wall tension increases with luminal radius and arterial pressure. Hence, as body mass (Mb) increases, associated increases in radius induces larger tension. Thus, it could be predicted that high tension would increase the potential for rupture of the arterial wall. Studies on mammals have focused on systemic arteries and have shown that arterial wall thickness increases with Mb and normalizes tension. Reptiles are good models to study scaling because some species exhibit large body size range associated with growth, thus, allowing for ontogenetic comparisons. We used post hatch American alligators, Alligator mississippiensis, ranging from 0.12 to 6.80kg (~ 60-fold) to investigate how both the right aortic arch (RAo) and the left pulmonary artery (LPA) change with Mb. We tested two possibilities: (i) wall thickness increases with Mb and normalizes wall tension, such that stress (stress = tension/thickness) remains unchanged; (ii) collagen content scales with Mb and increases arterial strength. We measured heart rate and systolic and mean pressures from both systemic and pulmonary circulations in anesthetized animals. Once stabilized alligators were injected with adrenaline to induce a physiologically relevant increase in pressure. Heart rate decreased and systemic pressures increased with Mb; pulmonary pressures remained unchanged. Both the RAo and LPA were fixed under physiological hydrostatic pressures and displayed larger radius, wall tension and thickness as Mb increased, thus, stress was independent from Mb; relative collagen content was unchanged. We conclude that increased wall thickness normalizes tension and reduces the chances of arterial walls rupturing in large alligators.

Survival, Growth, and Development in the Early Stages of the Tropical Gar Atractosteus tropicus: Developmental Critical Windows and the Influence of Temperature, Salinity, and Oxygen Availability

Alterations in fish developmental trajectories occur in response to genetic and environmental changes, especially during sensitive periods of development (critical windows). Embryos and larvae of Atractosteus tropicus were used as a model to study fish survival, growth, and development as a function of temperature (28 °C control, 33 °C, and 36 °C), salinity (0.0 ppt control, 4.0 ppt, and 6.0 ppt), and air saturation (control ~95% air saturation, hypoxia ~30% air saturation, and hyperoxia ~117% air saturation) during three developmental periods: (1) fertilization to hatch, (2) day 1 to day 6 post hatch (dph), and (3) 7 to 12 dph. Elevated temperature, hypoxia, and hyperoxia decreased survival during incubation, and salinity at 2 and 3 dph. Growth increased in embryos incubated at elevated temperature, at higher salinity, and in hyperoxia but decreased in hypoxia. Changes in development occurred as alterations in the timing of hatching, yolk depletion, acceptance of exogenous feeding, free swimming, and snout shape change, especially at high temperature and hypoxia. Our results suggest identifiable critical windows of development in the early ontogeny of A. tropicus and contribute to the knowledge of fish larval ecology and the interactions of individuals × stressors × time of exposure.

Quality considerations and malformation surveillance in a marine stocking program

Marine enhancement programs can be helpful for the conservation of important species. Many variables are considered in managing a marine enhancement program, and external fish quality prior to release should be one of them. Quality assessment aids in understanding the influence of rearing variables, limits a recognizable cultured fish phenotype, and maximizes the success of the conservation program by emulating the survivorship potential of wild stocks. We rear white seabass, Atractoscion nobilis, for stock enhancement and developed a semiquantitative assessment and control program to document and reduce the incidence of abnormal physical attributes prior to their release. Clearing and staining techniques were used to define normal processes of ossification, and wild fish surveys were performed to understand variability in natural stock morphology. In the hatchery, A. nobilis were examined in lots of 125 fish cohort –1 at 50 and 80 d post hatch of their development. Specimens evaluated were normal or classified as having malformations involving the bone or cartilage (13 categories) ranked 1–3, mild to severe. Malformations that were unique or differed substantially from wild A. nobilis specimens were culled from the cultured cohort as part of a quality control process prior to release. The most common malformations involved the head region, which accounted for 98% of all hard tissue malformations. Malformations of the jaws accounted for 30% of observed malformations and lower jaw prognathism was the most common observation. This program has proven useful for identifying malformations and minimizing the release of affected cultured marine fish.

Multi-stressor Effects of Ultraviolet Light, Temperature, and Salinity on Louisiana Sweet Crude Oil Toxicity in Larval Estuarine Organisms.

When oil is spilled into the environment its toxicity is affected by abiotic conditions. The cumulative and interactive stressors of chemical contaminants and environmental factors are especially relevant in estuaries where tidal fluctuations cause wide variability in salinity, temperature, and ultraviolet (UV) light penetration, which is an important modifying factor for polycyclic aromatic hydrocarbon (PAH) toxicity. Characterizing the interactions of multiple stressors on oil toxicity will improve prediction of environmental impacts under various spill scenarios. This study examined changes in crude oil toxicity with temperature, salinity, and UV light. Oil exposures included high-energy, water-accommodated fractions (HEWAFs) and thin oil sheens. Larval (24-48h post hatch) estuarine species representing different trophic levels and habitats were evaluated. Mean 96h LC50 values for oil prepared as a HEWAF and tested under standard conditions (20 ppt, 25°C, No-UV) were 62.5µg/L tPAH50 (mud snails), 198.5µg/L (grass shrimp), and 774.5µg/L (sheepshead minnows). Thin oil sheen 96h LC50 values were 5.3µg/L tPAH50 (mud snails), 14.7µg/L (grass shrimp), and 22.0µg/L (sheepshead minnows) under standard conditions. UV light significantly increased the toxicity of oil in all species tested. Oil toxicity also was greater under elevated temperature and lower salinity. Multi-stressor (oil combined with either increased temperature, decreased salinity, or both) LC50 values were reduced to 3µg/L tPAH50 for HEWAFs and < 1.0µg/L tPAH50 for thin oil sheens. Environmental conditions at the time of an oil spill will significantly influence oil toxicity and organismal response and should be taken into consideration in toxicity testing and oil spill damage assessments.

An ‘omics approach to investigate the growth effects of environmentally relevant concentrations of guanylurea exposure on Japanese medaka (Oryzias latipes)

Metformin is a widely prescribed pharmaceutical used in the treatment of numerous human health disorders, including Type 2 Diabetes, and as a results of its widespread use, metformin is thought to be the most prevalent pharmaceutical in the aquatic environment by weight. The removal of metformin during the water treatment process is directly related to the formation of its primary degradation product, guanylurea, generally present at higher concentrations in surface waters relative to metformin. Growth effects observed in 28-day early life stage (ELS) Japanese medaka exposed to guanylurea were found to be similar to growth effects in 28-day ELS medaka exposed to metformin; however, effect concentrations were orders of magnitude below those of metformin. The present study uses a multi-omics approach to investigate potential mechanisms by which low-level, 1 ng · L−1 nominal, guanylurea exposure may lead to altered growth in 28-day post hatch medaka via shotgun metabolomics and proteomics and qPCR. Specifically, analyses show 6 altered metabolites, 66 altered proteins and 2 altered genes. Collectively, metabolomics, proteomics, and gene expression data (using qPCR) indicate that developmental exposure to guanylurea exposure alters a number of important pathways related to the overall health of ELS fish, including biomolecule metabolism, cellular energetics, nervous system function/development, cellular communication and structure, and detoxification of reactive oxygen species, among others. To our knowledge, this is the first study to both report the molecular level effects of guanylurea on non-target aquatic organisms, and to relate molecular-level changes to whole organism effects.

Global tissue transcriptomic analysis to improve genome annotation and unravel skin pigmentation in goldfish

Goldfish is an ornamental fish with diverse phenotypes. However, the limited genomic resources of goldfish hamper our understanding of the genetic basis for its phenotypic diversity. To provide enriched genomic resources and infer possible mechanisms underlying skin pigmentation, we performed a large-scale transcriptomic sequencing on 13 adult goldfish tissues, larvae at one- and three-days post hatch, and skin tissues with four different color pigmentation. A total of 25.52 Gb and 149.80 Gb clean data were obtained using the PacBio and Illumina platforms, respectively. Onto the goldfish reference genome, we mapped 137,674 non-redundant transcripts, of which 5.54% was known isoforms and 78.53% was novel isoforms of the reference genes, and the remaining 21,926 isoforms are novel isoforms of additional new genes. Both skin-specific and color-specific transcriptomic analyses showed that several significantly enriched genes were known to be involved in melanogenesis, tyrosine metabolism, PPAR signaling pathway, folate biosynthesis metabolism and so on. Thirteen differentially expressed genes across different color skins were associated with melanogenesis and pteridine synthesis including mitf, ednrb, mc1r, tyr, mlph and gch1, and xanthophore differentiation such as pax7, slc2a11 and slc2a15. These transcriptomic data revealed pathways involved in goldfish pigmentation and improved the gene annotation of the reference genome.

Otolith-based approaches indicate strong effects of environmental variation on growth of a Critically Endangered estuarine fish

In estuaries, fluctuating environmental conditions exact strenuous physiological demands on the fishes that inhabit these oft-impacted areas, including the Critically Endangered delta smeltHypomesus transpacificusin California (USA). Using an archive of otoliths spanning 2011-2019, we examined how growth rates of wild subadult delta smelt vary ontogenetically, regionally, and in relation to variation in the physical environment during late-summer and fall in the upper San Francisco Estuary. Recent growth rates were quantified using otolith increment analysis and modeled as functions of both intrinsic (age) and extrinsic (temperature, salinity, clarity, and region) factors using a suite of generalized additive models. Age explained 60% of the variation in log10-transformed growth rates, which peaked at 50-80 d post hatch. Overall, age-adjusted growth rates declined at temperatures &gt;20°C, increased with practical salinity values of 0-4, and exhibited interactive patterns with water clarity. Growth rates appeared highest in the West and Central Delta, and lowest in the North Delta, also corresponding with patterns in environmental conditions. Here, we provide new evidence for how vital rates of wild delta smelt vary spatially and in relation to abiotic environmental variation. Such otolith-based growth reconstructions often provide the first direct look at how the vital rates of wild fish respond to environmental variationin situ, and how future changes are likely to affect the dynamics of wild populations.