Development Of Digestive Tract Research Articles

Light-modulated neural control of sphincter regulation in the evolution of through-gut

The development of a continuous digestive tract, or through-gut, represents a key milestone in bilaterian evolution. However, the regulatory mechanisms in ancient bilaterians (urbilaterians) are not well understood. Our study, using larval sea urchins as a model, reveals a sophisticated system that prevents the simultaneous opening of the pylorus and anus, entry and exit points of the gut. This regulation is influenced by external light, with blue light affecting the pylorus via serotonergic neurons and both blue and longer wavelengths controlling the anus through cholinergic and dopaminergic neurons. These findings provide new insights into the neural orchestration of sphincter control in a simplified through-gut, which includes the esophagus, stomach, and intestine. Here, we propose that the emergence of the earliest urbilaterian through-gut was accompanied by the evolution of neural systems regulating sphincters in response to light, shedding light on the functional regulation of primordial digestive systems.

Synbiotic inclusion effects on the quail’s (Coturnix coturnix japonica) performance and digestive tract development

Synbiotic inclusion effects on the quail’s (Coturnix coturnix japonica) performance and digestive tract development

Efficacy of maize differing in particle size in low-density protein diets fed to broilers from day 1 to 21 of age

ABSTRACT 1. This study evaluated the efficacy of maize differing in particle size in low-density protein diets on performance, the digestive tract and litter characteristics in broilers. Four dietary treatments; control commercial diet with a typical crude protein content 22.50% (CON); CON + 20% maize with particle size 350 µm (M350), crude protein 19.90%; CON + 20% maize with particle size 2600 µm (M2600), crude protein 19.90%; CON + 20% whole maize (WM), crude protein 19.90%, were fed ad libitum to broiler chicks up to 21 d of age. 2. No differences in body weight gain, feed intake and FCR were found between the WM and CON. WM increased body weight gain compared to M350 and M2600. M350, M2600 and WM increased (p = 0.004) gizzard relative weight compared with CON on day 14. Both WM and M2600 reduced (p = 0.001) gastric isthmus diameter on d 14 and 21 compared with CON and M350. 3. No differences were seen in mucosa for the Lamina propria and the extent of Tunica muscularis of gizzard on d 21 and ileum mucosal depth on d 14 between WM and CON diets. However, WM reduced villus-to-crypt ratio compared with CON on d 21. The M350 reduced (p < 0.05) gizzard digesta particle size compared with CON, M2600 and WM on d 14. 4. Both WM and M350 decreased (p < 0.05) nitrogen excretion compared to birds fed CON. Feeding WM increased nitrogen efficiency compared with M350 and M2600 diets, but was similar to birds fed CON. Feeding M350, M2600 or WM decreased (p < 0.05) litter moisture and footpad dermatitis (FPD) scores compared with results from birds fed CON. 5. Overall, diluting the protein level in broiler diets with whole maize appeared better than fine or coarse maize in terms of growth performance, digestive tract development, nitrogen excretion and litter parameters. This may lead to economic benefits by reducing grinding costs and dependence on rich protein resources contributing to sustainable meat production and food security.

Changes in Digestive Enzyme Activities during Larval Development of Spotted Seatrout (Cynoscion nebulosus)

The spotted seatrout (Cynoscion nebulosus)—an important commercial species—has a high potential for aquaculture in the Gulf of Mexico. To optimize its feeding during larval rearing, this study aims to evaluate the primary gastric (pepsin), intestinal (leucine aminopeptidase and alkaline phosphatase), and pancreatic (alkaline protease, trypsin, chymotrypsin, amylase, and lipase) enzyme activities from hatching to day 30. A multivariate analysis identified three digestive enzyme development stages during the spotted seatrout larval transformation. The first stage occurred between 1 (mean ± standard error (SE) = 1.73 ± 0.14 millimeter (mm) standard length (SL)) and 3 (2.14 ± 0.07 mm SL) days after hatching (DAH); a period of digestive stability showed the highest activity in amylase and bile salt-dependent lipase. The second stage (from 4 (2.53 ± 0.09 mm SL) to 20 (10.92 ± 0.51 mm SL) DAH) was a period of digestive transition, during which leucine aminopeptidase, chymotrypsin, and alkaline proteases were identified as the predominant enzymes from 4 to 5 DAH. In the third stage—a period of digestive stability—pepsin was the major enzyme that occurred between 25 (16.51 ± 0.81 mm SL) and 30 (25.91 ± 0.82 mm SL) DAH. These results indicate that the spotted seatrout larvae have a digestive system adapted to lipids and carbohydrates at the onset of feeding, with an immediate transition to protein digestion when exogenous feeding begins. Additionally, the digestive system of the spotted seatrout may be considered mature at 25 DAH. Further research is needed to elucidate the mechanisms of digestive tract development in the spotted seatrout larvae.

Influence of graded levels of maize distillers dried grains with solubles (mDDGS) on the performance, digestive tract development and carcass characteristics of broilers

Abstract The present study investigated the feeding value of maize distillers dried grains with solubles (mDDGS) for broiler chickens. As the first step, the nutrient composition, apparent metabolisable energy (AME) and apparent ileal amino acid digestibility of mDDGS were determined. These values were used to formulate iso-nutrient and isocaloric diets to evaluate the influence of graded levels of mDDGS on broiler performance, digestive tract development and carcass characteristics. Five maize-soybean based diets containing 0 or 5, 10, 15 and 20% of mDDGS, were formulated and cold-pelleted at 65 °C. Each diet was offered ad libitum to six replicates (eight birds per replicate cage) during starter (day 1–21) and finisher (day 22–35) phases. The mDDGS was analysed to contain (% dry matter (DM) basis): CP, 27.8; total non-starch polysaccharides, 28.6 and soluble non-starch polysaccharides, 5.6. The AME was determined to be 10.23 MJ/kg DM. The average ileal digestibility coefficient of indispensable AA was 0.826. The Inclusion of 20% mDDGS resulted in poorer (P &lt; 0.05) feed per gain (quadratic effect, P &lt; 0.05) during the starter period, but no negative effects (P &gt; 0.05) were observed finisher period and the overall production period (day 1–35). Feed intake and feed per gain (linear effect, P &lt; 0.05) decreased with increasing inclusions of mDDGS during finisher period and overall period. A tendency (P = 0.06) for linear improvement in excreta quality was observed with increasing inclusion levels of mDDGS. Relative digestive tract weights and carcass and breast meat yields were not influenced (P &gt; 0.05) by dietary treatments. A linear (P &lt; 0.05) decrease was observed for the relative lengths of jejunum, ileum and the small intestine. The results indicated that, when balanced for metabolisable energy and digestible amino acids, mDDGS can be incorporated into broiler starter and finisher diets up to 15 and 20%, respectively, with no adverse effects on live performance, carcass characteristics or excreta quality.

Rack1-mediated ferroptosis affects hindgut development in rats with anorectal malformations: Spatial transcriptome insights.

Anorectal malformation (ARM), a common congenital anomaly of the digestive tract, is a result of insufficient elongation of the urorectal septum. The cytoplasmic protein Receptor of Activated C-Kinase 1 (Rack1) is involved in embryonic neural development; however, its role in embryonic digestive tract development and ARM formation is unexplored. Our study explored the hindgut development and cell death mechanisms in ARM-affected rats using spatial transcriptome analysis. We induced ARM in rats by administering ethylenethiourea via gavage on gestational day (GD) 10. On GDs 14-16, embryos from both normal and ARM groups underwent spatial transcriptome sequencing, which identified key genes and signalling pathways. Rack1 exhibited significant interactions among differentially expressed genes on GDs 15 and 16. Reduced Rack1 expression in the ARM-affected hindgut, verified by Rack1 silencing in intestinal epithelial cells, led to increased P38 phosphorylation and activation of the MAPK signalling pathway. The suppression of this pathway downregulated Nqo1 and Gpx4 expression, resulting in elevated intracellular levels of ferrous ions, reactive oxygen species (ROS) and lipid peroxides. Downregulation of Gpx4 expression in the ARM hindgut, coupled with Rack1 co-localisation and consistent mitochondrial morphology, indicated ferroptosis. In summary, Rack1, acting as a hub gene, modulates ferrous ions, lipid peroxides, and ROS via the P38-MAPK/Nqo1/Gpx4 axis. This modulation induces ferroptosis in intestinal epithelial cells, potentially influencing hindgut development during ARM onset.

Digestive Tract Development of Crossbreed Native Chickens due to Effect of Terminalia catappa Leaf (T. catappa L) Extract in Drinking Water

The purpose of the current study was to clarify the impact of drinking water extract from Terminalia catappa leaves on the development of the native chicken crossbreeds’ digestive systems. The study was set up with 4 treatments and 4 replications in a properly randomized design (5 bird for each replication). Water without Terminalia catappa leaf extract (T0), water with 3% of Terminalia catappa leaf extract for three days per week (T1), water with 3% of Terminalia catappa leaf extract for five days per week (T2), and water with 3% of Terminalia catappa extract for seven days per week (T3) were the study’s treatments (T3). Parameters observed are relative weight of digestive organs, length of digestive organs, and weight to length ratio of digestive organs. Results show that Terminalia catappa leaf extract in drinking water showed a significant effect in weight to length ratio of duodenum but had no effect in the other digestive organ. The use of Terminalia catappa leaf extract have a potensial effect to maintance digestive tract development.

Invited review: Total solids concentration in milk or milk replacer for dairy calves

Restricting milk or milk replacer (MR) fed to dairy calves to 10% of body weight at 12.5% total solids (TS) concentration is a common feeding strategy that promotes early weaning and lowers total feed costs for raising young calves. However, this strategy has been associated with inferior performance and compromised welfare. Because a restricted liquid nutrition plan limits calf growth due to limited supply of nutrients, research on increased supply of nutrients from liquid has shown improved growth, health, and welfare of calves. Nutrient supply may be increased by feeding larger amounts of milk or MR averaging 12.5% TS, or by increasing TS above the usual 12.5% TS by increasing MR TS concentration alone (TS+), or by increasing TS concentration and volume simultaneously (TSV+). The objective of this review is to discuss liquid nutrition plans with greater TS concentration in MR or in milk diets, considering the effects of such strategies on performance and digestive tract development before weaning and the future performance of dairy calves. This review will focus on liquid nutrition plans that are based on increased TS concentration (i.e., TS+ or TSV+); therefore, enhanced liquid nutrition plans based only on increased volumes will not be the discussed. Improved growth rates have been observed in calves fed TSV+ programs. However, reduced starter intake preweaning can also have negative effects on dry matter intake, average daily gain, and digestibility postweaning. Feeding a TS+ program may reduce impairment of starter intake and therefore have positive effects on performance, nutrient digestibility, and health. When considering an accelerated nutrition plan with TS+ or TSV+, it is important to consider osmolality of the liquid diet. Further studies are necessary to confirm this hypothesis and the cost-benefit of alternative liquid nutrition plans, as well as the optimal TS concentration of milk or MR fed to dairy calves.

Feeding concentrate with hay of different qualities modulates rumen histology, development of digestive tract as well as slaughter performance and meat quality of young dairy calves

ABSTRACT Concentrate-rich starter diets are commonly fed to dairy calves to stimulate growth performance. However, feeding high amounts of starter feed with low inclusion of forage fibre may jeopardise the development of the gastrointestinal tract (GIT). Moreover, studies investigating the effects of feeding on carcass and meat quality of young calves at rearing are rare. The objective of this research was to investigate the effect of hay quality and concentrate inclusion on the traits of GIT development, slaughter performance and veal quality of young dairy calves. The feeding trial covered the first 14 weeks of life. Seventeen male and three female Holstein calves (n = 20) were randomly allocated to four experimental groups, which received besides acidified whole milk different solid feeds: (1) 100% medium-quality hay (MQH), (2) 100% high-quality hay (HQH), (3) 30% medium-quality hay and 70% concentrate (MQH+C) and (4) 30% high-quality hay and 70% concentrate (HQH+C). The acidified whole milk was fed in the first 12 weeks of life, and calves had ad libitum access to solid feed and water from birth till slaughter. Calves were kept in individual boxes equipped with straw and slaughtered at the end of week 14. After slaughter, gut development traits, rumen histology, slaughter performance and meat quality were assessed. Overall, both concentrate inclusion and hay quality showed major effects on rumen histology and development of the GIT in dairy calves with minimal effects on most carcass cuts and meat quality traits. Concentrate-fed calves had significantly higher average daily gains, final body weights, blood amounts and proportions of organs from the circulatory and respiratory systems. Proportions of liver and kidneys were lowest in MQH-fed calves. The proportion of GIT was significantly lower in groups fed concentrates, but the weight of the reticulorumen was unaffected by solid feed. Concentrate feeding led to thicker keratin layer and epithelium as well as wider papillae in the rumen. Hay quality particularly affected the width of the papilla and epithelium thickness, while feeding hay without concentrate enhanced the thickness of submucosa and muscularis, as well as the size of parotid glands. In conclusion, the type of solid feed affects the development of the GIT with concentrate feeding holding the risk to induce keratinisation of rumen epithelium while enhancing performance and carcass traits.

Effect of IOF and its interaction with post-hatch feeding procedure on hatchability, some organs development and post-hatch performance in broiler chickens.

Under commercial conditions, chickens are fasted for the first 36 to 72h post-hatch. Delayed access to feed and water causes delayed development of the intestinal tract and retarded performance. This study focused on the chick's life as affected by in ovo feeding (IOF) and the animal's interaction with the feeding procedure. The birds in a factorial arrangement (2 × 3) were placed into six treatment groups in a completely randomised design. The treatment groups differed in feed procedure, 6h [early feeding (EF)] or 36h [common feeding (CF)] post-hatch, with or without IOF with beta-hydroxy-beta-methyl butyrate (HMB) or calcium gluconate (CG) in a saline solution, and were examined for hatchability and performance parameters until 24h post-hatch. In addition, physical and histological characteristics of breast, jejunum and serum indices in 14 days post-hatch and performance criteria until 35 days of age were recorded. On day 17 of the incubation period, eggs were subjected to the IOF procedure. One mL of sterile IOF solution including 0.1% HMB or 0.4% CG dissolved in 5% saline solution was injected into the eggs. Results showed that IOF groups had lower (p < 0.05) FCR than the control group. The highest mortality rate was noted in the control-CF group. The lowest myofibril density was related to the HMB-CF group. Myofibril periphery, area and diameter for the HMB-CF group were larger (p < 0.05) than those of the other groups. Results indicated that injection of HMB increased hatchability by almost 15%. The IOF of HMB improved the digestive tract and breast muscle development and improved FCR.

Case report: Novel homozygous HPGD variant leads to primary hypertrophic osteoarthropathy with intussusception and acro-osteolysis in a Chinese family.

To perform molecular genetic analysis of a patient diagnosed with primary hypertrophic osteoarthropathy (PHO) with malnourishment, intussusception, and acro-osteolysis. At the age of 7 years, a boy born to a consanguineous couple was diagnosed with PHO attributed to delayed closure of the cranial suture, eczema, clubbing of fingers, and swelling of the knee and ankle. Clinical characteristics and follow-up data for 3 years were collected and analyzed. Trio whole-exome sequencing (WES) and copy number variant sequencing were used to screen for causative genetic variants. Candidate variants of the patient and his parents were confirmed by Sanger sequencing. When he was 7 years old, trio WES found that he had biallelic novel variants c.498 + 1G > A, inherited from his parents, in the HPGD gene. The patient was markedly malnourished. Ultrasonography and computed tomography showed intussusception with a gradual expansion of the duodenum, localized intestinal wall thickening, and acro-osteolysis. Cross-sectional blood tests showed that the patient had continuously decreased levels of serum 25-hydroxy vitamin D and serum ferritin at the age of 7and 10 years. PHO due to HPGD defects is rare in pediatric patients, and finding homozygous novel c.498 + 1G > A has expanded the spectrum of causative variants of HPGD and provided a clue for genotype-phenotype correlation analysis. Similar to mouse model results, human HPGD deficiency may also cause abnormal digestive tract development, and related secondary vitamin D deficiency and acro-osteolysis should be considered in HPGD-related PHO.

An integrated transcriptome and microbial community analysis reveals potential mechanisms for increased immune responses when replacing silybum marianum meal with soybean meal in growing lambs.

Silybum marianum meal is a by-product that remains silymarin complex and is perceived as a potential-protein source. The potential and its mechanism of silybum marianum meal as a protein supplement in ruminants were evaluated by testing the growth performance, biochemical parameters, cytokine levels, gut transcriptome and microbial community profiles. Forty-two male Hulunbeier growing lambs (aged about 3-month-old; averaged body weight of 21.55 kg) were randomly divided into the CON (with 10% soybean meal) and SIL groups (with 10% silybum marianum meal). There was no significant difference in growth performance, feed intakes, or serum biochemical parameters between CON and SIL. The serum levels of IL-1β, TNF-α, TGF-β, HGF, and VEGF were all increased (p < 0.05) in the SIL group as compared with the CON group. Transcriptome gene set enrichment analysis (GSEA) revealed that the core genes in the rumen from SIL group were enriched with fructose and mannose metabolism, while the core genes in the ileum were enriched for three biological process, including digestive tract development, positive regulation of MAPK cascade, and regulation of I-kappaB kinase/NF-kappaB signaling. The 16S rDNA results showed that the relative abundance of Bacteroidetes, Firmicutes, Synergistetes, and Verrucomicrobia in the rumen from SIL group was significantly higher than that in CON group (p < 0.05), whereas Proteobacteria was significantly lower than that in CON group (p < 0.05). The LEfSe analysis showed that the genera Pyramidobacter, Saccharofermentans, Anaerovibrio, Oscillibacter and Barnesiella were enriched in the rumen from SIL group, whereas Sharpea was enriched in the CON group (LDA > 2). In the ileum, there were no significant differences in the phylum-level classification of microbes observed. At the genus level, the relative abundances of Bifidobacterium and Ruminococcus in the ileum from SIL group were significantly higher than that in the CON group (p < 0.05), whereas the relative abundance of Clostridium_XI was lower (p < 0.05). Correlation analysis showed that Clostridium_XI was negatively correlated with VEGF, TGF-β, TNF-α and HGF (p < 0.05). Core genes BMP4 and CD4 were negatively correlated with Clostridium_XI (p < 0.05). Our results indicated that supplementing silybum marianum meal as a replacement for soybean meal resulted in increased cytokines production without affecting growth performance in growing lambs, and the enrichment of immune-related genes and altered microbial community in the ileum were contributed to the increased immune responses.

Effects of curcumin on the growth performance, apparent nutrient digestibility, intestinal morphology, digestive enzyme activity, and antioxidant capacity of meat rabbits

The purpose of this study was to investigate the effect of curcumin on the growth performance, slaughter performance, apparent nutrient digestibility, intestinal morphology, and digestive enzyme activity of meat rabbits. One hundred and sixty healthy weaned meat rabbits were randomly divided into four groups (forty replicates per group and one rabbit per replicate). The control group was fed a basal diet and the test groups (T1, T2 and T3) were fed diets supplemented with 50, 100 and 150 g/t curcumin in the basal diet, respectively. The study lasted for 28 days, including a pre-feeding period of 7 days and a formal trial period of 21 days. The results showed that diets supplemented with curcumin significantly increased rabbits’ body weight gain and average daily feed intake; Apparent digestibility of energy, crude protein, crude fat, crude fibre, NDF and ADF; Jejunal villus height, the ratio of villus height to crypt depth; The activities of amylase and lipase in jejunal and caecal digesta and cellulase in caecal digesta; Caecal mucosal thickness, eviscerated dressing percentage, and dorsal and abdominal hair thickness (p < .05). Diets supplemented with curcumin significantly decreased rabbits’ feed to gain ratio, jejunal crypt depth and thickness of the intestinal wall (p < .05). In conclusion, curcumin is a kind of valuable feed additive, which can improve the nutrient digestibility, growth performance, slaughter ratio and fur development of meat rabbits by improving digestive tract development and digestive enzyme activity. The appropriate dosage in the meat rabbit diet is 100 g/t. HIGHLIGHTS Dietary supplementation of curcumin improved the growth performance, gastrointestinal digestive enzyme activities and slaughter performance of meat rabbits. Dietary supplementation of curcumin increased the antioxidant capacity of meat rabbits. Curcumin could be used as a new kind of feed additive for meat rabbits.

Effects of Dietary Sodium and Chloride on Slaughter Performance, Digestive Tract Development and Tibia Mineralization of Geese

This study evaluated the slaughter performance, digestive tract development and tibia mineralization effects of sodium (Na) and chloride (Cl) on geese. Four hundred and thirty-four male geese at 29 days were randomly assigned into nine groups with six replicates (eight in each). The experiment employed a 3 × 3 factorial design, with two instances each of three Na levels (0.10%, 0.15%, and 0.20%) and three Cl levels (0.15%, 0.20%, and 0.25%). All experimental birds were husbanded for 42 days. Dietary Na and Cl levels and their interactions (Na ×Cl) had no significant effect on the slaughter, breast, thigh, abdominal fat yield, and digestive tract index of geese (p > 0.05). However, dietary Na and Cl level significantly affected the crypt depth of the jejunum and tibial development. Variations in Na and Cl levels had a significant interaction on the crypt depth of jejunal (p < 0.05), 0.20% Na × 0.25% Cl had a minor crypt depth. Dietary variations in Na and Cl significantly affected the tibial strength, and there was a significant interaction between them (p < 0.05). When Na and Cl were at their maximum (0.20% Na and 0.25% Cl), the strength of the tibia was the lowest. In addition, a single factor (Na or Cl) had no effect (p > 0.05), but its interaction significantly affected the calcium (Ca) content of bone (p < 0.05). When the Na and Cl levels were 0.15% and 0.15%, respectively, the Ca content in bone was the highest. These results suggest that dietary Na and Cl had interactive effects on geese, especially in the development of the tibia. High dietary Na and Cl levels adversely influenced the tibia and intestinal crypt morphology. Therefore, we do not advocate supplementing too much Na or Cl in the diet. Combined with our previous results, for 29-70-day-old geese, it is recommended that dietary Na and Cl levels should be 0.10% and 0.15%, respectively.

Growth performance, carcass characteristics, serum biochemistry and digestive tract development in broiler chickens fed with chitosan oligosaccharide

Growth performance, carcass characteristics, serum biochemistry and digestive tract development in broiler chickens fed with chitosan oligosaccharide

Ontogenetic Development of Digestive Tract and Enzymes Activity in Hatchery-reared Pink Ear Emperor, Lethrinus lentjan Larvae

Ontogenetic development of the digestive tract and associated organs of Lethrinus lentjan larvae were learned by observing changes in external morphology, histology, and enzymatic changes from hatchling to 40-day post-hatching (dph). Ontogenetic development of the L. lentjan digestive system can be divided into three major stages; the first stage from hatching of larvae to complete absorption of yolk-sac, which ends on 2 dph, the second stage from 3 to 15 dph i.e., from exogenous feeding to the formation of the gastric gland and third stage till completion of metamorphosis (35 dph). Pyloric caeca were developed after 20 dph, which was formed entirely by 27 dph. Enzymatic activities of amylase, lipase, trypsin and chymotrypsin were detected before the onset of exogenous feeding and pepsin was detected from 19 dph onwards in L. lentjan. So considering both histology of digestive tract and enzyme development, weaning of L. lentjan larvae to artificial diet can be practiced after 19-20 dph coinciding with the formation of pyloric caeca and production of pepsin enzyme for better digestibility and consequently better growth and survival. The present study can be expended as a reference guide to understand the digestive tract development and successful hatchery rearing of other economically important marine fishes.

The Effects of Plant Protein-Enriched Live Food on Larval Zebrafish Growth and the Status of Its Digestive Tract Development.

Live food is necessary for the proper development of zebrafish larvae, providing nutrition in a form that is easily digestible and available to the larvae. Live food is commonly enriched to increase the dietary content of certain nutrients. However, little research has been done on protein-based enrichments, especially those of plant origin. This study sought to examine how different quality protein enrichments affected the composition of live food as well as growth and digestive tract development of larval zebrafish, Danio rerio. Larval zebrafish were fed from 3 to 22 days posthatch (dph) with one of six live food (rotifers Brachionus plicatilis and Artemia spp.) treatments: (1) live food with no enrichment (starved; control); (2) live food enriched with commercially used Spirulina spp. algae; (3) live food enriched with soybean meal (SBM); (4) live feed enriched with soy protein concentrate (SPC); (5) live feed enriched with a fishmeal hydrolysate; and (6) live feed enriched with intact fishmeal (FM). Proximate composition of live food was significantly affected by enrichment, in particular, protein content of rotifers was significantly increased by enrichment with SBM. Zebrafish fed SBM-enriched live food showed longer total body length than all other groups, except SPC. Zebrafish in the SBM group also showed increased gene expression of chymotrypsin in the intestine, possibly indicating improved intestinal development and extracellular digestion, which likely contributed to improved growth. Conversely, zebrafish fed hydrolysate-enriched live food showed reduced gene expression of alkaline phosphatase, possibly indicating a less developed intestinal tract, correlating with reduced growth compared to SBM group. Overall, plant protein was shown to be a promising source of live food enrichment for improving larval zebrafish growth.

Characterizing the gastrointestinal development and digestive enzyme ontogeny of larval Amphiprion ocellaris

Clownfish (Amphiprion ocellaris) are the most recognizable and popular marine aquarium fish and are a key commodity for marine ornamental fish producers. Although these fish have been raised in captivity for decades, producers are still experiencing issues regarding larval survival, reliance on live feeds, and post-larval deformities. To improve the culture process, the ontogeny of larval development and digestive capacity should be elucidated. The morphological development, digestive enzyme ontogeny, and digestive tract development of A. ocellaris was examined in a 16-day trial. Standard microplate assays were conducted to quantify the activity of trypsin, lipase, and acid protease enzymes from 24 h before hatching to 15 days post hatch (DPH). Histology was used to visualize morphological changes in the digestive tract throughout the larval period. At hatching, A. ocellaris has functional eyes, an open mouth, and a coiled, differentiated digestive tract. Trypsin and lipase activities were detectable before hatching and increased significantly later in the larval period. Gastric gland formation was observed at 6 DPH, with stomach functionality occurring between 7 and 9 DPH, indicated by gastric gland proliferation and an increase in acid protease activity. The results from this study may be used to inform weaning protocols to maximize larval growth and survival while minimizing the use of costly live feeds.

Distribution, Biology and Ontogeny of Indian River Shad (Tenualosa ilisha)

The distribution, biology and ontogenic development of the Indian River Shad (Tenualosa ilisha) compared with some other fishes compile in this review. The distribution in the inland waters of Bangladesh, stock/race, movement and migration pattern, size and sex ratio, age of reproduction, maturity and fecundity and ontogenic development of the mouth, digestive tract and accessory gland of T. ilisha discussed in this article. The life cycle of a fish starts after fertilization, but the mouth and digestive tract development start after hatching. Yolk sac larvae (3.83 ± 0.57 mm SL), pre flexion larvae (8.07 ± 1.83 mm SL), flexion larvae (11.50 ± 1.55 mm SL), post flexion larvae (14.72 ± 1.70 mm SL), and juvenile (18.75 ± 3.02 mm SL) were separated into five groups based on morphological characteristics. At the yolk sac stage, the mouth was closed, however at the pre-flexion stage, the larval mouth gape varied between 177 ± 25 and 367 ± 47 µm. The ranges were 241 ± 31 and 497 ± 59 µm, for the flexion stage, 307 ± 38 and 621 ± 74 µm for the post-flexion stage, and 393 ± 61 and 788 ± 119 µm for the early juvenile stage. Development of the digestive tract is complete at the juvenile stage of this species.

Morphological changes in the digestive tract of the Chinese soft-shelled turtle (Pelodiscus sinensis) during embryonic development

ABSTRACT The digestive tract development of the Pelodiscus sinensis embryo is described through the observation of the embryonic morphology on hematoxylin and eosin stained tissue sections. During the first 9 days of embryonic development, the anterior intestine of the embryo divides into the oral cavity, pharyngeal cavity, esophagus, stomach, and small intestine, while the caudal intestine differentiates into the cloaca, the anterior and caudal tubes of the large intestine. Between days 10–24, the wall of the digestive tract forms a two-layer structure consisting of mucosa and submucosa. The endoderm evolves into epithelial tissue in each part of the digestive tract, the mesoderm goes from a dense cluster of cells to looser mesenchymal tissue then divides into loose connective tissue, mesothelium, and muscle tissue. There is no clear temporal boundary between development of mesenchymal tissue and the early loose connective tissue, which is a gradual process.