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Broodstock rearing is fundamental to produce high-quality offspring for aquaculture. However, reproduction requires large amounts of energy and nutrients, and physiological activities of digestive enzymes determine the absorption of energy and nutrients. However, the interaction between reproduction and digestive physiology is still unclear in sea cucumbers. In this study, we used laboratory experiments and field investigations to assess the variations of digestive physiology and digestive function in the sea cucumber Apostichopus japonicus during reproduction. Unexpectedly, activities of both amylase and trypsin were depressed in adult sea cucumbers during reproduction under both laboratory and field conditions. As a physiological consequence, digestive efficiencies of energy and organic matter decreased significantly during reproduction. Although reproductive output of sea cucumbers varied greatly between laboratory and wild conditions, reproductive effort had no effect on the activities of numerous digestive enzymes. Together, these data indicated that reproductive status induced digestive function decline in A. japonicus. Our study provided very important information about the reproductive biology of sea cucumbers that could be applied to broodstock rearing and conservation of this commercially important species. [ABSTRACT FROM AUTHOR]

Abstract Background The tigerfish (Hydrocynus forskahlii) is an important food fish in different regions of Africa. As such, interest in its performance and nutritional requirements as a potential candidate for aquaculture is increasing. Characterization of the morpho-histological features and functions of the gut provides valuable insights into the feeding physiology and digestive system of fish species. Result An investigation of the morpho-histological features of the gastrointestinal tract of H. forskahlii captured from Lake Albert was conducted over an eight-month period. The digestive tract of H. forskahlii is characterised by a short oesophagus, well-developed and distensible stomach and moderately long intestine. The oesophagus had a higher abundance of mucous-secreting goblet cells compared to other digestive tract tissues. The stomach had a bag-like shape for swallowing large prey and was distinguishable into the cardiac, fundic and pyloric regions. Both the cardiac and fundic regions of the stomach had numerous gastric glands, whereas the pyloric region had large compound folds consisting of pseudo-stratified columnar epithelium. Many goblet cells were also observed in the mid and posterior regions of the intestine. The relative length of the gut of the H. forskahlii was 1.27 ± 0.03 cm, and it had a total of 20–22 pyloric caeca. The liver was observed to be divided in lobules by a central vein contained within connective sheets. Irregular cords of hepatocytes were also visible throughout the parenchyma. Conclusions The histological features of the H. forskahlii gut observed in the present study are consistent with those of carnivorous and omnivorous fish.

Simple Summary: This study evaluated the effect of dietary supplementation with organic silicon on the growth performance, blood biochemistry, digestive enzymes, morphohistology, intestinal microbiota and stress resistance in juvenile hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus). It is concluded that organic silicon had no negative effects on the physiology and metabolism of the fish. The results showed that up to 50 mg·kg−1 of organic silicon can be applied to the diet of red Tilapia, improving digestive, metabolic and growth performance. The interactions between zootechnical performance, physiological digestive and metabolic capacity in hybrid red Tilapia still deserve further exploration. In recent decades, interest has been aroused worldwide in the use of silicon in nutrition; however, information on its effect on nutrition and metabolism of fish is limited. The objective of the research was to evaluate the effect of dietary supplementation with organic silicon on the growth performance, blood biochemistry, digestive enzymes, morphohistology and intestinal microbiota and stress resistance in hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus). Methodologically, six levels of organic silicon (DOS) [control (0), 10, 20, 30, 40 and 50 mg·kg−1] were used to feed juvenile fish (initial weight 7.51 ± 0.25 g) grown for eight weeks in 18 aquariums (15 fish/aquarium). The results indicated that growth performance showed differences (p < 0.05) for specific growth rate, feed conversion and survival. Triglycerides, cholesterol and glucose, transaminases and digestive enzymes were significantly influenced by DOS levels. The histological study confirmed that the administered diets did not cause damage and induced significant morphological changes in the proximal intestine. The 16S rRNA gene sequencing analysis of the gut microbiota showed a high diversity and richness of OTU/Chao-1, with Fusobacteria, Proteobacteria, Bacteroidetes and Acidobacteria predominating in the DOS treatments compared to the control (p < 0.05). Induction of hypoxia stress after the feeding period showed a significant relative survival rate of 83.33% in fish fed 50 mg·kg−1. It is concluded that the DOS treatments performed better than the control treatment in most of the variables analysed. DOS had no negative effects on the fish. The results showed that up to 50 mg·kg−1 DOS improved digestive, metabolic and growth performance in hybrid Tilapia. [ABSTRACT FROM AUTHOR]

Background: The tigerfish (Hydrocynus forskahlii) is an important food fish in different regions of Africa. As such, interest in its performance and nutritional requirements as a potential candidate for aquaculture is increasing. Characterization of the morpho-histological features and functions of the gut provides valuable insights into the feeding physiology and digestive system of fish species. Result: An investigation of the morpho-histological features of the gastrointestinal tract of H. forskahlii captured from Lake Albert was conducted over an eight-month period. The digestive tract of H. forskahlii is characterised by a short oesophagus, well-developed and distensible stomach and moderately long intestine. The oesophagus had a higher abundance of mucous-secreting goblet cells compared to other digestive tract tissues. The stomach had a bag-like shape for swallowing large prey and was distinguishable into the cardiac, fundic and pyloric regions. Both the cardiac and fundic regions of the stomach had numerous gastric glands, whereas the pyloric region had large compound folds consisting of pseudo-stratified columnar epithelium. Many goblet cells were also observed in the mid and posterior regions of the intestine. The relative length of the gut of the H. forskahlii was 1.27 ± 0.03 cm, and it had a total of 20–22 pyloric caeca. The liver was observed to be divided in lobules by a central vein contained within connective sheets. Irregular cords of hepatocytes were also visible throughout the parenchyma. Conclusions: The histological features of the H. forskahlii gut observed in the present study are consistent with those of carnivorous and omnivorous fish. [ABSTRACT FROM AUTHOR]

The effects of intermittent starvation on the growth, precocity, digestive enzyme activity, feeding, and body chemical composition of the juvenile Chinese mitten crab Eriocheir sinensis were investigated in two independent experiments. Crabs were reared individually during Experiment I and cultured in aggregate during Experiment II. Five treatments were tested in both experiments. Crabs in the control group (Group C) were fed continuously and, in Groups S3, S6, S10, and S15, were starved and then re-fed for 3, 6, 10, and 15 days, respectively. The precocity rate of Group C was significantly higher than that of the other groups. In Experiment I, the final mean body weight and the mean specific growth rate in dry matter of Groups C and S3 were significantly higher than those of the other groups. In Experiment II, the mean specific growth rate in body weight in Group C was similar to that of Groups S3, S6, and S10 but significantly higher than that of Group S15. Crabs in Groups S3, S6, and S10 compensated for starvation-induced growth depression after being re-fed, and compensatory growth was achieved via both higher feeding rate and improved feed efficiency. There was no significant difference in trypsin and alkaline phosphatase activity, while steapsin and amylase activity were significantly affected by the starvation period. There was no significant difference in dry matter, ash, and protein content among Groups C, S3, S6, and S10 in Experiment I. The results demonstrated that proper intermittent starvation was sufficient for reducing the precocity rate of cultured juvenile E. sinensis, and it is recommended that juvenile crabs be subjected to intermittent fasting for 6 to 10 days to maintain precocity rates at acceptable levels without inhibiting growth and yield. [ABSTRACT FROM AUTHOR]

Objective: The Blackbanded Sunfish Enneacanthus chaetodon is a small centrarchid that is endemic to slow‐moving waters from New Jersey to central Florida, United States. The distribution of this species has been increasingly fragmented, primarily due to habitat degradation. The development of larval culture protocols is essential to produce this species for the aquarium trade and for potential restoration efforts. To streamline the production process, larvae should be transitioned from live feeds to inert diets as early as possible without sacrificing larval growth or survival. Methods: A developmental trial was conducted to determine the timing of digestive tract maturation, which indicates the ability of larvae to better digest inert microdiets (MDs). Blackbanded Sunfish larvae were sampled 12 times from 2 days posthatch (dph; notochord length [mean ± SD] = 4.38 ± 0.22 mm) to 50 dph (total length [TL] = 9.89 ± 1.64 mm) for subsequent analysis of digestive enzyme activity (via microplate assays) and digestive system morphology (via histology). A dietetics trial was conducted to determine the most appropriate commercial MD for this species at early life stages by testing the efficacy of three different MDs against a reference diet of brine shrimp Artemia nauplii. Lastly, a weaning trial was conducted to determine the earliest time point at which MDs should be introduced during the larval period. Result: Blackbanded Sunfish larvae transitioned from agastric to gastric digestion at approximately 40 dph (7.95 ± 0.86 mm TL), as determined by the presence of gastric glands and pepsin activity. In the dietetics trial, certain MDs yielded higher survival than others; however, all diets performed equally when considering the TL of the larvae. In the weaning trial, the highest survival was found when larvae were fed Artemia nauplii exclusively or when an MD was introduced at 48 dph (10.62 ± 1.88 mm TL). Conclusion: Larval Blackbanded Sunfish may require up to 48 days of live feeds before introducing MDs but can be successfully transitioned to MDs after 48 dph without significantly affecting survival or growth. Impact statementThe Blackbanded Sunfish, a species with threatened populations throughout its endemic range, can be successfully aquacultured to aid in potential population restoration initiatives or to supply fish for the aquarium trade. [ABSTRACT FROM AUTHOR]

Botanical based-insecticides are presently recognized to interfere behavioral and physiological performances of herbivorous insects. In the current study, the insecticidal properties of Pimpinella anisum, Foeniculum vulgare and Heracleum persicum essential oils (EOs), and their main component, trans-anethole, were studied on a destructive pest of mulberry leaves, Glyphodes pyloalis Walker. The effect of essential oils (EOs) on the larval feeding was evaluated by the leaf-dipping method and demonstrated the highest insecticidal and antifeedant activities of F. vulgare and H. persicum. Apart from negative effects on feeding indices, feeding treatment with the EOs significantly inhibited the activities of digestive enzymes and acetylcholinesterase (AChE). At nearly, all the tested compounds increased the activities of detoxifying and antioxidant enzymes. Thus, these EOs demonstrate potential as new control products to combat G. pyloalis, and they may function as an insecticide, antifeedant, or inhibitor of physiological performance. [ABSTRACT FROM AUTHOR]

Although all hystricomorph rodents have the colonic furrow or groove that is the anatomical prerequisite for a 'mucous trap' colonic separation mechanism linked to coprophagy or cecotrophy, the taxon that gives this group its name, the porcupines, have been claimed to not practice coprophagy. Absence of coprophagy has repeatedly been claimed for hystricomorph species in which it was later confirmed. Here, we report the observation of a characteristic posture—sitting on one hindleg, with the other hindleg lifted and the snout covering the anogenital region—that is the typical posture during coprophagy in other large hystricomorph rodents, in two zoo-managed Indian crested porcupines (Hystrix indica). Together with other circumstantial evidence, these observations are suggestive of coprophagy in porcupines, and support claims that it may be wise to assume all hystricomorph rodents can use this strategy. [ABSTRACT FROM AUTHOR]

In recent decades, interest has been aroused worldwide in the use of silicon in nutrition; however, information on its effect on nutrition and metabolism of fish is limited. The objective of the research was to evaluate the effect of dietary supplementation with organic silicon on the growth performance, blood biochemistry, digestive enzymes, morphohistology and intestinal microbiota and stress resistance in hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus). Methodologically, six levels of organic silicon (DOS) [control (0), 10, 20, 30, 40 and 50 mg·kg−1] were used to feed juvenile fish (initial weight 7.51 ± 0.25 g) grown for eight weeks in 18 aquariums (15 fish/aquarium). The results indicated that growth performance showed differences (p < 0.05) for specific growth rate, feed conversion and survival. Triglycerides, cholesterol and glucose, transaminases and digestive enzymes were significantly influenced by DOS levels. The histological study confirmed that the administered diets did not cause damage and induced significant morphological changes in the proximal intestine. The 16S rRNA gene sequencing analysis of the gut microbiota showed a high diversity and richness of OTU/Chao-1, with Fusobacteria, Proteobacteria, Bacteroidetes and Acidobacteria predominating in the DOS treatments compared to the control (p < 0.05). Induction of hypoxia stress after the feeding period showed a significant relative survival rate of 83.33% in fish fed 50 mg·kg−1. It is concluded that the DOS treatments performed better than the control treatment in most of the variables analysed. DOS had no negative effects on the fish. The results showed that up to 50 mg·kg−1 DOS improved digestive, metabolic and growth performance in hybrid Tilapia.

ABSTRACT: Radix rehmanniae preparata polysaccharide (RRPP) is recognized as the primary bioactive compound in Radix rehmanniae preparata and has been extensively utilized in traditional Chinese medicine and functional food due to its diverse biological activities. However, this study has yet to explore the application of RRPP as a feed additive in broilers. This study investigated the effects of dietary RRPP on growth performance, meat quality, and physiological responses of broiler chickens. Two hundred eighty-eight 1-day-old Cobb 500 male broilers were randomly assigned to the 4 experimental groups with 6 replications and 12 birds/replicate. The 4 groups were fed the basal diet supplemented with 4 concentrations of RRPP (0, 300, 600, and 900 mg/kg, respectively). All RRPP levels did not affect the growth performance of broilers during the starter period (1–21 d), while during the grower (22–35 d) and overall (1–35 d) periods, body weight gain, feed conversion ratio, and European production efficiency index were linearly improved (P < 0.05) by incorporating RRPP at 600 and 900 mg/kg. Carcass characteristics, relative weight and length of intestinal segments, and meat quality and tibia criteria were not affected by dietary incorporation of RRPP. Dietary RRPP led to a linear increase (P < 0.05) in serum alkaline phosphatase, potassium, calcium and sulfhydryl levels, while reducing concentrations of hydrogen peroxide, LDL, triglycerides and total cholesterol. The addition of RRPP decreased (P < 0.05) the pH of the ileum and cecum at 21 and 35 d of age while not changing in the remaining intestinal segments. Dietary RRPP at 600 and 900 mg/kg linearly and quadratically (P < 0.05) increased the tibia ash content in chicken at 21 and 35 d of age. In conclusion, dietary supplementation of RRPP improved broiler chicken's growth, gut physiology, and tibia ash content, particularly at 600 and 900 mg/kg.

We investigated the effects of finely ground wheat bran on the nutrient digestibility, digesta passage rate, and gut microbiota structure in sows. A 3 × 3 Latin square design with 3 test periods and 3 experimental diets was used. Six non-pregnant sows (parity: 5 to 7) were randomly assigned to 3 experimental diets with 2 replicates per treatment in each period. Each period lasted 19 d (12 d for adaptation and 7 d for experiment). The experimental diets included (a) a basal corn and soybean meal diet (CON), (b) a basal diet with 20% coarse wheat bran (CWB; particle size: 605 μm), and (c) a basal diet with 20% fine wheat bran (FWB; particle size: 438 μm). The results demonstrated that the apparent total tract digestibility of neutral detergent fiber, acid detergent fiber and energy were reduced (P

Biotic interactions can modulate the responses of organisms to environmental stresses, including diet changes. Gut microbes have substantial effects on diverse ecological and evolutionary traits of their hosts, and microbial communities can be highly dynamic within and between individuals in space and time. Modulations of the gut microbiome composition and their potential role in the success of a species to maintain itself in a new environment have been poorly studied to date. Here we examine this question in a large wood-boring beetle Cacosceles newmannii (Cerambycidae), that was recently found thriving on a newly colonized host plant. Using 16S metabarcoding, we assessed the gut bacterial community composition of larvae collected in an infested field and in "common garden" conditions, fed under laboratory-controlled conditions on four either suspected or known hosts (sugarcane, tea tree, wattle, and eucalyptus). We analysed microbiome variation (i.e. diversity and differentiation), measured fitness-related larval growth, and studied host plant lignin and cellulose contents, since their degradation is especially challenging for wood-boring insects. We show that sugarcane seems to be a much more favourable host for larval growth. Bacterial diversity level was the highest in field-collected larvae, whereas lab-reared larvae fed on sugarcane showed a relatively low level of diversity but very specific bacterial variants. Bacterial communities were mainly dominated by Proteobacteria, but were significantly different between sugarcane-fed lab-reared larvae and any other hosts or field-collected larvae. We identified changes in the gut microbiome associated with different hosts over a short time frame, which support the hypothesis of a role of the microbiome in host switches. [ABSTRACT FROM AUTHOR]

Adopting a new diet is a significant evolutionary change, and can profoundly affect an animal's physiology, biochemistry, ecology and genome. To study this evolutionary transition, we investigated the physiology and genomics of digestion of a derived herbivorous fish, Cebidichthys violaceus. We sequenced and assembled its genome (N50 = 6.7 Mb) and digestive transcriptome, and revealed the molecular changes related to digestive enzymes (carbohydrases, proteases and lipases), finding abundant evidence of molecular adaptation. Specifically, two gene families experienced expansion in copy number and adaptive amino acid substitutions: amylase and carboxyl ester lipase (cel), which are involved in the digestion of carbohydrates and lipids, respectively. Both show elevated levels of gene expression and increased enzyme activity. Because carbohydrates are abundant in the prickleback's diet and lipids are rare, these findings suggest that such dietary specialization involves both exploiting abundant resources and scavenging rare ones, especially essential nutrients, like essential fatty acids.

To understand the drivers of variation in digestive performance and their effects on growth, we examined relationships among food consumption, digestive metabolism, food processing efficiency, and growth rate in juveniles of fast‐growing piscivore versus slow‐growing insectivore ecotypes of rainbow trout reared at satiation rations on the same diet (i.e., commercial food pellets). Relative to slow‐growing insectivores with lower basal metabolism, and despite a much larger maximum food ration, faster‐growing piscivores presented an unexpected pattern of higher digestive efficiency through a reduction in the absolute costs of postprandial metabolism coupled with shorter or similar gut residence time and higher assimilation efficiency. These results suggest that the increase in digestive metabolism following the ingestion of larger meals can be mitigated by displacing the costs of digestion from SDA to SMR. Reducing total digestion costs (SDA + SMR) while maintaining higher assimilation efficiency may be possible through potential adaptations including (1) increased intestinal absorption capacity; (2) economies of scale that shorten gut transit time with increasing ration level; or (3) a permanently larger digestive tract that increases maintenance costs but reduces the need for cyclic upregulation and associated overhead costs. [ABSTRACT FROM AUTHOR]

The populations of three members of the Neotropical silverside fish from the Poblana genus of the Atherinopsidae family (Poblana alchichica, P. letholepis, and P. squamata) are microendemic species restricted to the eastern basin of central Mexico, where each Poblana species is limited to each crater lake. The aim of this study was to characterize the potential differences in functionality and diversity of digestive proteases between three Poblana species as a likely result of physiological digestive adaptations over the speciation process. Adults of the three Poblana species were collected from three different crater lakes and the activity of digestive proteases and their functional characteristics under different pH and temperature conditions and the number and size of alkaline proteases were determined using biochemical and electrophoretic techniques. The three Poblana species showed acid protease activity and high chymotrypsin activity; likewise, the optimum pH was 8 for alkaline proteases and ranged between 2 and 3 for acid proteases. Alkaline proteases showed an optimum temperature peak at 60°C, while acid proteases showed two peaks (at 30°C and 60°C). The presence of aspartyl peptidases in all three species was confirmed using an inhibitor pepstatin A. The SDS-PAGE zymogram showed four activity bands with alkaline proteolytic activity (45.4, 39.0, 27.9, and 17.4 kDa) in P. alchichica, five bands (58.0, 45.4, 39.0, 27.9, and 17.4 kDa) in P. letholepis, and five bands (126.9, 69.7, 39.0, 27.9, and 17.4 kDa) in P. squamata. Therefore, the studied Poblana display slight differences in protease function and in the number of protease isoforms as a result of allopatric speciation processes and probably of diet selectivity. [ABSTRACT FROM AUTHOR]

Simple Summary: The marbled flounder (Pseudopleuronectes yokohamae) is a fish species with high commercial value in Korea and has been gaining attention as a new aquaculture target. To clarify the digestive physiology and feeding habits of the marbled flounder, this study conducted morphological, histological, and histochemical analyses of its digestive tract. In conclusion, the feeding habits of marbled flounder are close to those of carnivorous fish. In addition, we found that the marbled flounder has a stomach with a structure suitable for eating small amounts of hard food, and that most of its digestion takes place in the anterior intestine portion. Our study presents the histological and histochemical characteristics of the digestive tract of the marbled flounder, providing basic knowledge for both physiological and nutritional studies. This study investigated the morphological, histological, and histochemical characteristics of the digestive tract of the marbled flounder (Pseudopleuronectes yokohamae). The relative length of the gut of the marbled flounder digestive tract was 1.54 ± 0.10 (n = 20), and it had a simple stomach and 6–9 pyloric caeca. The mucosal folds of the marbled flounder digestive tract exhibited a general branched morphology. The thickness and mucosal fold length of the intestinal muscularis externa showed similar aspects in all areas. The thickness of the intestinal muscularis externa was the thickest in the posterior intestine portion, and the length of mucosal folds was the longest in the anterior intestine portion. It was indicated that food digested by gastric acid in the stomach moves to the anterior portion (including pyloric caeca) and mid portion of the intestine, ensuring effective stimulation of cholecystokinin (CCK)-producing cells. In addition, the distribution pattern of CCK-producing cells in the intestine was very similar to that of mucus-secreting goblet cells. The CCK-producing cells and goblet cells in the marbled flounder were well-adapted to promote optimal control of the digestive process. Based on the morphological and histochemical studies, it was concluded that the marbled flounder displays a digestive tract comparable to that of fish species with carnivorous habits. [ABSTRACT FROM AUTHOR]

Simple Summary: Beluga and sevruga are two highly valuable sturgeon species from the Acipenseride family in Iran. In recent years, research has been focused on commercial rearing of these species. A very important aspect in the sturgeon farming industry is the development of formulated compound diets for promoting growth. However, the ability of fish to digest compound diets is mostly related to the existence of the digestive enzymes in different parts of the gastrointestinal tract. In gastric species, protein digestion is conducted along the gastrointestinal tract by several proteases such as pepsin, trypsin, and chymotrypsin. Trypsin, as an alkaline protease, is able to hydrolyze protein residues and peptides to release free amino acids and small peptides for intestinal absorption; therefore, the activity of trypsin has been widely used as a valuable indicator of digestive capacity in fish. In this work, we aimed to characterize trypsin from beluga and sevruga for the first time. The results of our study show that the physicochemical and biochemical properties of trypsin from beluga and sevruga were in agreement with data reported in bony fish and may be considered a preliminary step to design in vitro tests for the assessment of protein digestibility in these primitive species. This work aimed to determine the physicochemical and biochemical properties of trypsin from beluga Huso huso and sevruga Acipenser stellatus, two highly valuable sturgeon species. According to the results obtained from the methods of casein-zymogram and inhibitory activity staining, the molecular weight of trypsin for sevruga and beluga was 27.5 and 29.5 kDa, respectively. Optimum pH and temperature values for both trypsins were recorded at 8.5 and 55 °C by BAPNA (a specific substrate), respectively. The stability of both trypsins was well-preserved at pH values from 6.0 to 11.0 and temperatures up to 50 °C. TLCK and SBTI, two specific trypsin inhibitors, showed a significant inhibitory effect on the enzymatic activity of both trypsins (p < 0.05). The enzyme activity was significantly increased in the presence of Ca+2 and surfactants and decreased by oxidizing agents, Cu+2, Zn+2, and Co+2 (p < 0.05). However, univalent ions Na+ and K+ did not show any significant effect on the activity of both trypsins (p > 0.05). The results of our study show that the properties of trypsin from beluga and sevruga are in agreement with data reported in bony fish and can contribute to the clear understanding of trypsin activity in these primitive species. [ABSTRACT FROM AUTHOR]

Optimally foraging animals should minimise time spent foraging in order to perform other fitness-enhancing activities. The ruminants' more efficient digestive system, requiring lower volumes of forage, is predicted to provide an advantage over hindgut fermenters with respect to foraging effort, but this may be offset by their need for higher quality forage. We contrasted the activity of two similarly-sized, syntopic grazers, black wildebeest (Connochaetes gnou), a ruminant, and Cape mountain zebra (Equus zebra zebra), a hindgut fermenter, using camera trap data and tested the volume-requirement and the nutrient-driven hypotheses, seasonally. Zebra and wildebeest activity varied seasonally, potentially due to differences in resource availability. In winter, a greater proportion of wildebeest were recorded grazing relative to zebra, supporting the nutrient-driven hypothesis, whilst the inverse occurred (although not significantly) in summer, supporting the volume-requirement hypothesis. Seasonal variation in resources may provide temporal foraging trade-offs of benefits for ruminants and hindgut fermenters. [ABSTRACT FROM AUTHOR]

ABSTRACT: Changle goose in Fujian, China is a rare genetic resource and in urgent need to be protected. Understanding the characteristics of digestive physiology and spatial variation of gastrointestinal microbiota is crucial for developing nutritional intervention strategies to improve intestinal health and production performance of goose. Hence, histomorphological assay was used for observing development status of proventriculus, jejunum, and cecum in 70-day-old Changle geese, whereas digesta from 6 alimentary canal locations (crop, proventriculus, gizzard, jejunum, cecum, and rectum) were collected for 16S rRNA gene sequencing and short chain fatty acids (SCFAs) quantitative analysis. The histomorphological observation indicated that the jejunum and cecum of Changle goose were well developed. The alpha diversity analysis revealed that, except rectum, microbiota in other noncecum sections were in high diversity as cecum. The Nonmetric MultiDimensional Scaling (NMDS) analysis showed that microbial community of proventriculus, gizzard, and jejunum formed a cluster, which distinctly discrete with the microbiota of the other gastrointestinal locations. Additionally, the proportions of Proteobacteria, Bacteroidota, and Campilobacterota at the phylum level and Lactobacillus, Streptococcus, Helicobacter, and Subdoligranulum at the genus level exhibited tremendous alternations among different gastrointestinal locations. The characteristic bacterial composition in each section was further disclosed by analyzing the core and feature Amplicon Sequence Variants (ASVs) and SCFAs pattern. Importantly, 7 body-weight-associated ASVs and 2 cecum-development-related ASVs were identified via correlation analysis. In a whole, our findings provided the first insights into the specialized digestive physiology of Changle geese and distinctive regional distribution of gastrointestinal microbiota, which laid the important foundation for improving growth performance through microbiota manipulation in geese.

Simple Summary: Diversification of cultured fish species is one key measure to promote the sustainable development of marine aquaculture. Mullets (Mugilidae) present great potential due to their eurythermal, euryhaline, and low-trophic nature. However, there are many similar mullet species, and their physiological differences and optimal culture conditions are quite unknown, mainly when reared under intensive systems. In this sense, increasing the knowledge about changes in their digestive biochemistry related to feeding strategies is essential for a sustainable and cost-effective culture of these species. For these reasons, the present study aimed to characterize the digestive biochemistry of two mullet species (Chelon labrosus and Liza aurata) and to evaluate how it is affected when fish are fed using two different feeding frequencies: one or three times per day. In addition, changes in the potential bioavailability of nutrients determined by the two feeding patterns were assessed using digestive simulations performed in vitro. The results demonstrated the convenience of a feeding pattern of three meals per day instead of one. Moreover, the results evidenced that although Chelon labrosus and Liza aurata are species placed in a similar trophic level, their digestive response to feeding patterns, as well as body composition, present differences when fish are reared under the same conditions. This suggests that such interspecific variation must be considered when fish are reared under intensive conditions. Mullets (Mugilidae) present significant potential for sustainable aquaculture diversification due to their eurythermal, euryhaline, and low-trophic nature. However, the physiological differences and optimal cultured conditions among the diverse mullet species are quite unknown. For these reasons, the present study aimed to address two main objectives: (1) to characterize the differences in digestive biochemistry, somatic indexes, and body composition between two mullet species (Liza aurata and Chelon labrosus); and (2) to evaluate the interactions of two different feeding frequencies (one against three meals per day) on the above-mentioned parameters, and also on the potential bioavailability of nutrients determined using in vitro assays. The results evidenced higher protease and amylase activities for Chelon labrosus than for Liza aurata, while the latter species presented a higher percentage of eviscerated weight and muscle lipids. Furthermore, the results from in vitro assays supported the higher enzyme activity of Chelon labrosus by an observed increase in the release of amino acids and reducing sugars measured for this species. Regarding feeding patterns, the results of the in vitro assays simulating enzyme: substrate (E:S) ratios corresponding to one or three meals per day point to a clear increase of nutrient bioavailability when the daily ration is split into several meals. The present results improve the physiological knowledge of mullet species and define criteria to develop better management protocols by producers. [ABSTRACT FROM AUTHOR]

The presently reported study was aimed to determine the effects of graded levels of dietary pink oyster mushroom (Pleurotus djamor) meal (POMM), in growth, feed efficiency, protein utilization, digestive enzymes activities, and whole-body proximate composition of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), fingerlings (0.3 ± 0.01 g). The experimental design included a control diet (POMM0) formulated with soybean meal, as the main protein source, and four diets designed with increasing levels of POMM: 25% (POMM25); 50% (POMM50); 75% (POMM75); and 100% (POMM100). Experimental diets were administered to 420 fish, randomly distributed in 15, 100-L tanks. The feeding experiment lasted 45 days. Diets and the final whole body were submitted to a proximate composition analysis. Growth, feed efficiency, protein utilization, and digestive enzyme activities were assessed. Compared to POMM0 and POMM25, weight gain (WG), and specific growth rate (SGR), significantly (P < 0.05) decreased in fish that were fed POMM50, POMM75, and POMM100%. Feed conversion ratio (FCR), protein efficiency ratio (PER), and survival rate (SR) were not significantly affected by experimental diets. Daily feed intake (DFI), and daily protein intake (DPI), decreased as POMM increased in diets. Compared to POMM0 experimental group, condition factor (K), showed a significantly higher value in fish that were fed POMM50, and POMM100 experimental diets. Crude fiber of the final whole body of POMM100 resulted in significantly higher (P < 0.05) compared to that shown in fish fed the rest of the experimental diets. Acid and alkaline proteases, trypsin, chymotrypsin, leucine aminopeptidase, and amylase of Nile tilapia fingerlings, were not significantly affected by experimental diets. Compared to fish fed POMM0 and POMM25 diets, experimental fish fed POMM50, POMM75, and POMM100 showed a reduction in lipase activity. In conclusion, a POMM level higher than 25% affects growth and lipase activity. While a POMM level higher than 50% affects fiber content in a whole body of the final fish. [ABSTRACT FROM AUTHOR]

Flying lemurs are able to glide using a thin membrane of skin (patagium) connected to their limbs, body, and part of tails. The Malayan flying lemur (Galeopterus variegatus) is endemic to Southeast Asia. Previous information on food habits of this species has been anecdotal, and few studies on their dietary composition have been conducted. From the information of sibling species, we predicted that the Malayan flying lemurs to be folivorous. We firstly tried a quantitative analysis of the dietary compositions of the Malayan flying lemurs together with food availability in West Java, Indonesia, throughout the year. The Malayan flying lemurs seasonally changed foods: leaves from December to July largely overlapping with the rainy season (October–June) and fruits from August to November largely overlapping with the dry season (July–September). When fruits were abundant, the proportions of fruits in the feces increased while proportions of leaves in the feces decreased, or the flying lemur shifted their foods from leaves to fruits. In this period, tree leaves were abundant, which did not explain the decrease in the feces. This implies that the flying lemurs fed on tree leaves in the majority of the year but they shifted to fruits when they were abundant though leaves were also abundant. The abrupt changes in the dietary composition of the flying lemurs were different from those of the sympatric folivorous primate, Javan lutung (Trachypithecus auratus), for which dietary composition showed a gradual change from leaves to fruits. Such inter-specific differences would be caused by differences in body sizes and/or digestive physiology. [ABSTRACT FROM AUTHOR]

The toxicity of a tea saponin (TS) was investigated on mortality, digestive system, detoxifying and antioxidant enzymes of Ephestia kuehniella Zeller. The larvae were fed on a diet containing different concentrations of TS (5, 10, 20, 40, and 80 mg/mL) to determine the lethal dose and the lethal exposure time. The LC50 of TS was calculated as 28 mg/mL while the LT5 value was found to be 4.14 days following the bioassay experiment. The activities of all enzymes except for lipase decreased in the TS-fed larvae, while the activities of general esterase and glutathione S-transferases as the detoxification enzymes significantly increased contradictory. Moreover, the larvae fed on TS demonstrated the higher activities of antioxidant enzymes including superoxide dismutase, peroxidase, and catalase in addition to the content of malondialdehyde. These findings indicated the significant toxic effects of TS on inhibition of digestive activities and induction of antioxidant enzymes which developed our knowledge on physiological disruptions due to TS treatment. [ABSTRACT FROM AUTHOR]

Sieve analyses of hindgut contents of horses as well as observations in horses where plastic markers had been applied to a caecal cannula suggested that there may be a discrimination by particle size in the passage or retention of digesta. Here, we performed a similar experiment with five caecum‐cannulated horses (562 ± 31 kg) fed a constant amount (6.81 kg dry matter/day) of grass hay. Passage markers representing the liquid (Co‐EDTA) as well as the particulate digesta phase (Yb—undefined; Cr mordanted fibre 1−2 mm; Ce‐mordanted fibre 8 mm) were given as a pulse‐dose into the cannula to measure their mean retention times (MRT). The MRTs were compared by repeated‐measurements analysis of variance. The MRT in the hindgut was 22.2 ± 2.4 h for Co, 25.0 ± 3.4 h for Yb, 26.2 ± 1.6 h for Cr and 26.3 ± 1.5 h for Ce. Whereas differences between the particle marker MRTs were not significant (padj. > 0.05), significant differences were observed between the solute marker Co and each of the particle markers Cr and Ce (padj. < 0.009). The results confirm the well‐known significant, albeit small, difference in MRT in horses between the fluid and the particle digesta phase, and corroborate another recent study that used a combination of whole, marked hay and individual marker analysis in different particle size fractions of the faeces, which also did not detect a selective retention of any particle size class. [ABSTRACT FROM AUTHOR]

In investigations of differences between ruminant species feeding on browse or grass, it is often unclear whether observed differences are animal‐ or forage‐specific. Ruminant species have been classified as 'moose‐type', with little rumen content stratification, or 'cattle‐type' with a distinct rumen contents stratification, including a gas layer. To which extent putative differences in forestomach motility are involved in these patterns is unknown. Using sonography, we investigated the frequency of reticular contractions and the stratification of rumen contents in goats fed exclusively on grass hay (n = 6) or dried browse (n = 5) directly after feeding, and after another 6 and 12 h with no access to feed. The frequency of reticular contractions decreased from immediately after feeding (1.8 ± 0.3 min−1) to 6 h afterwards (1.2 ± 0.2 min−1) and then remained constant, with no difference between diets. A gas dome became more visible over time, but neither its incidence nor its extent differed between diets. The results are in accord with classifying goats as 'cattle‐type' in terms of their digestive physiology, and they add to a growing body of evidence that differences in digestive physiology between ruminant species are more due to species characteristics than different kinds of ingested forages. [ABSTRACT FROM AUTHOR]

Spodoptera littoralis (Boisd) is a worldwide pest of economic importance for agricultural crops. We investigated nutritional efficiency and digestive enzyme activity of S. littoralis on various mung bean cultivars, including Parto, Simite1, Simite2, VC6173A, VC3960, VC6368 and VC6371. Furthermore, various biochemical traits of mung bean cultivars, including protein, starch, total phenolic and flavonoid content, were measured to investigate their relationships with nutritional physiology of S. littoralis. The nutritional indices, as well as proteolytic and amylolytic activities of S. littoralis were significantly affected by feeding of the pest on various mung bean cultivars. Larvae reared on VC6371 exhibited the highest efficiency of conversion of digested food, while the lowest was recorded in those fed on Simite2. Spodoptera littoralis larvae fed on the Simite1 cultivar exhibited the lowest relative growth rate, while those reared on Simite2 were characterized by the lowest efficiency of conversion of ingested food. The highest proteolytic activity of sixth‐instar larvae was on VC6371, while the lowest activity was on VC3960, Simite1 and Simite2 cultivars. Amylolytic activity was the lowest in those larvae fed on VC6368 and VC6371 cultivars, while the highest activity occurred in larvae reared on Simite2. Significant variation in phytochemical contents was quantified among tested mung bean cultivars. Moreover, significant correlations were found between the nutritional indices and digestive enzyme activities of S. littoralis with biochemical properties of the cultivars. Our results suggest that VC6371 is a suitable cultivar for S littoralis, while Simite2 and Simite1 cultivars are less suitable and may be useful selections to minimize damage caused by this pest. [ABSTRACT FROM AUTHOR]

Food processing and consumption by herbivores are affected differently by the availability of forage quality and quantity per unit of time. This demonstrates the "Allometric response concept", and it is considered a significant determinant in habitat use for foraging by grazers. The relevance of this approach has comprehensively been applied to herbivores of different body sizes, but little is known about its demonstration to explain patch use in herbivores with different digestive physiology and body size. We explain the use of patches by grazing herbivores of different digestive physiology and body sizes, Hippopotamus amphibius (hippopotamus, mega non-ruminant) and cattle (ruminant), by integrating foraging relationship herbivores. We analysed the significant relationships between species dropping densities and environmental variables across forty-eight 100 m×100 m plots in Bui National Park, Ghana, during the wet and dry seasons. We found that both species utilised areas closer to the river in the wet season, but the H. amphibius foraged further away from the river during the dry season. Sward height also determined patch use by both species, with the H. amphibius utilising shorter swards than the cattle. Considering the quality of food resources, the study revealed that patch selection of ruminants (cattle) was significantly influenced by nitrogen content. In contrast, acidic detergent fibre content was positively related to non-ruminant species (H. amphibius). The high seasonal effect of sward height and food quality on patch use is primarily due to the species digestive physiology and body size of hippopotamus and cattle at the Bui National Park. [ABSTRACT FROM AUTHOR]

Abstract Quantitative differences in calcium and phosphorus metabolism between domestic species exist and can be visualised using data on calcium and phosphorus intake and faecal excretion. The parameter for analysing the results was defined as Δ = dietary calcium/phosphorus (Ca/P) ratio – faecal Ca/P ratio. In previous studies, hindgut fermenters had significantly higher Δ values than ruminants (sheep, cattle, goats), which was explained by the high calcium digestibilities in hindgut fermenters in contrast to highly efficient phosphorus recycling in ruminants. The first hypothesis of the present study was that different types of ruminants (grazer, browser, intermediate feeder) would show differences in Δ as a proxy for quantitative calcium and phosphorus metabolism. The second hypothesis was that camelids as functional, but not taxonomic ruminants would show Δ values similar to ruminants. We used herbivorous zoo animals (17 species, hindgut and foregut fermenters), which were kept on their regular diet without variation for 1 week. Then, faecal samples were obtained from the individual animals. Feed items and faecal samples were analysed for calcium and phosphorus, and dietary and faecal Ca/P ratios as well as Δ were calculated. A comparison of the species groups (one‐way ANOVA on ranks, p

Simple Summary: During metabolizable energy evaluation for feedstuffs, the feedstuffs being tested are usually incorporated into a standard diet. High levels of substitution of the test feedstuff into the standard diet inevitably result in changes to the chemical profile of the newly composited diet. Such changes may result in very high levels of fiber, protein, or other components, but the effects of such changes on growth performance, gut health, or nutrient transport in the intestine are usually not investigated. In the current study, the inclusion of low-protein soybean meal, wheat bran, soy hull, corn gluten feed, or rice bran resulted in increased soluble and insoluble fibers as well as protein content of the final diet depending on feedstuff incorporated into the standard diet. The chemical changes also resulted in, relative to the standard diet, enhanced or depressed weight gain, nutrient utilization, nutrient transporter mRNA, and profile of cecal short-chain fatty acids. Therefore, it is important to consider the gut health influence of test feedstuffs in test diets for metabolizable energy experiments. The current study was conducted to investigate the influence of short-term feeding of test diets during metabolizable energy assays on growth performance, nutrient utilization, jejunal histomorphology, cecal short-chain fatty acids, and nutrient transporters in broilers. One hundred twenty-six broiler chickens were assigned to six treatments, each with seven replicates. Experimental diets were fed between days 14 and 21. Treatments included a corn–soybean meal reference diet and five test diets with low-protein soybean meal (LPSBM), wheat bran, soy hull, corn gluten feed, or rice bran. Birds were weighed on days 14 and 21; excreta, cecal content, and jejunal tissues were collected on day 21. Seven-day weight gain was highest (p < 0.01) for birds receiving the reference diet or LPSBM, whereas FCR was lowest (p < 0.05) for birds receiving the soy hull diet. Cecal acetate and total short-chain fatty acids were higher (p < 0.05) for wheat bran compared with the soy hull test diet. Jejunal villi were longer (p < 0.05) for chickens receiving the reference diet or LPSBM test diet. Glucose transporter (GLUT1) mRNA was greater (p < 0.05) in broilers receiving rice bran compared with soy hull test diets. Therefore, when reporting energy assays, it is important that indicators of animal growth or gut health be included to help contextualize energy utilization. [ABSTRACT FROM AUTHOR]

To reveal direct effects of various protein sources on digestive physiology of red seabream, Pagrus major (38.5 ± 0.4 g), six different protein sources of fishmeal (FM), soybean meal (SBM), corn gluten meal (CGM), soy protein concentrate (SPC), poultry by-product meal (PBM), and poultry-feather meal (PFM) were orally administered to fish (2 mg protein/g body weight) and sampled at 1.5 h and 3 h after administration. Gallbladder weight of fish administered FM, PBM, and PFM decreased after administration (p < 0.0001), while no difference was observed in the other ingredients compared to a non-protein sham control group, indicating that animal protein sources could more strongly stimulate bile secretion than plant protein sources in red seabream. Trypsin and chymotrypsin activity in the intestinal content markedly increased by the FM, SBM, and PFM administration (p < 0.0001). Lipase and amylase activity was also increased by FM and SBM but also by CGM for lipase and by PBM and PFM for amylase (p < 0.0001). These indicate that stimulation effect of the secretion of digestive enzymes is largely different among the protein sources. This might be due to the absorptive capacity of the protein source since intestinal absorption parameter genes (anpep, cpa, ggt1, and atp1a2) also increased by the FM, SBM, PBM or PFM (p < 0.05). In addition to the secretion levels of bile and digestive enzymes, gene expression levels of bile related genes (cyp7a1, cyp8b1, and shp) and digestion-regulating genes (casr and cck) were increased by the FM, SBM, PFM, and/or PBM administration, suggesting that animal proteins and SBM could be potent digestive stimulants compared to CGM and SPC. This study first revealed that single protein sources directly influence digestive enzyme secretion and bile secretion in fish. Information about the direct effect of each single source on digestive physiology could help to design feed formulation with less fishmeal. [ABSTRACT FROM AUTHOR]

The gut microbiome plays a vital role in health and wellbeing of animals, and an increasing number of studies are investigating microbiome changes in wild and managed populations to improve conservation and welfare. The short-beaked echidna (Tachyglossus aculeatus) is an iconic Australian species, the most widespread native mammal, and commonly held in zoos. Echidnas are cryptic animals, and much is still unknown about many aspects of their biology. Furthermore, some wild echidna populations are under threat, while echidnas held in captivity can have severe gastric health problems. Here, we used citizen science and zoos to collect echidna scats from across Australia to perform the largest gut microbiome study on any native Australian animal. Using 16S rRNA gene metabarcoding of scat samples, we characterised and compared the gut microbiomes of echidnas in wild (n = 159) and managed (n = 44) populations, which were fed four different diets. Wild echidna samples were highly variable, yet commonly dominated by soil and plant-fermenting bacteria, while echidnas in captivity were dominated by gut commensals and plant-fermenting bacteria, suggesting plant matter may play a significant role in echidna diet. This work demonstrates significant differences between zoo held and wild echidnas, as well as managed animals on different diets, revealing that diet is important in shaping the gut microbiomes in echidnas. This first analysis of echidna gut microbiome highlights extensive microbial diversity in wild echidnas and changes in microbiome composition in managed populations. This is a first step towards using microbiome analysis to better understand diet, gastrointestinal biology, and improve management in these iconic animals. [ABSTRACT FROM AUTHOR]

This study investigated the morphological, histological, and histochemical characteristics of the digestive tract of the marbled flounder (Pseudopleuronectes yokohamae). The relative length of the gut of the marbled flounder digestive tract was 1.54 ± 0.10 (n = 20), and it had a simple stomach and 6–9 pyloric caeca. The mucosal folds of the marbled flounder digestive tract exhibited a general branched morphology. The thickness and mucosal fold length of the intestinal muscularis externa showed similar aspects in all areas. The thickness of the intestinal muscularis externa was the thickest in the posterior intestine portion, and the length of mucosal folds was the longest in the anterior intestine portion. It was indicated that food digested by gastric acid in the stomach moves to the anterior portion (including pyloric caeca) and mid portion of the intestine, ensuring effective stimulation of cholecystokinin (CCK)-producing cells. In addition, the distribution pattern of CCK-producing cells in the intestine was very similar to that of mucus-secreting goblet cells. The CCK-producing cells and goblet cells in the marbled flounder were well-adapted to promote optimal control of the digestive process. Based on the morphological and histochemical studies, it was concluded that the marbled flounder displays a digestive tract comparable to that of fish species with carnivorous habits.

This work aimed to determine the physicochemical and biochemical properties of trypsin from beluga Huso huso and sevruga Acipenser stellatus, two highly valuable sturgeon species. According to the results obtained from the methods of casein-zymogram and inhibitory activity staining, the molecular weight of trypsin for sevruga and beluga was 27.5 and 29.5 kDa, respectively. Optimum pH and temperature values for both trypsins were recorded at 8.5 and 55 °C by BAPNA (a specific substrate), respectively. The stability of both trypsins was well-preserved at pH values from 6.0 to 11.0 and temperatures up to 50 °C. TLCK and SBTI, two specific trypsin inhibitors, showed a significant inhibitory effect on the enzymatic activity of both trypsins (p < 0.05). The enzyme activity was significantly increased in the presence of Ca+2 and surfactants and decreased by oxidizing agents, Cu+2, Zn+2, and Co+2 (p < 0.05). However, univalent ions Na+ and K+ did not show any significant effect on the activity of both trypsins (p > 0.05). The results of our study show that the properties of trypsin from beluga and sevruga are in agreement with data reported in bony fish and can contribute to the clear understanding of trypsin activity in these primitive species.

Fibre content and its effect on chyme viscosity are associated with changes in the digestive system of humans and pigs. It is unclear if fibre content and viscosity affect digestive function independently or interactively. We evaluated apparent ileal digestibility (AID) of nutrients and intestinal function in thirty-six ileal-cannulated barrows fed for 29 d either maize–soyabean meal (MSBM) or high-fibre MSBM + 30 % distillers dried grains with solubles (MSBM + DDGS) modified to three levels of viscosity by adding 5 % non-viscous cellulose (CEL), 6·5 % medium-viscous carboxymethylcellulose (MCMC) or 6·5 % high-viscous CMC (HCMC). Digesta were collected on days 27 and 28 and intestinal samples on day 29. Feeding CMC, regardless of fibre content, increased viscosity of whole digesta (P = 0·003) and digesta supernatant (P < 0·0001) compared with CEL. Feeding MSBM + DDGS or CMC decreased AID of DM (P = 0·003; P < 0·0001) and crude protein (P = 0·02; P < 0·0001) compared with MSBM or CEL. Feeding CMC regardless of fibre content increased jejunal crypt depth (P = 0·02) and ileal goblet cell area (P = 0·004) compared with CEL. Adding DDGS or CMC did not affect villus height and gene expression of jejunal monosaccharide and amino acid transporters. Feeding HCMC, regardless of fibre content, elevated amylase activity by 46 and 50 % in jejunal (P = 0·03) and ileal digesta (P = 0·01) compared with CEL. In summary, diets with increased viscosity decreased nutrient digestibility and induced intestinal changes that were independent of the amount of fibre fed. [ABSTRACT FROM AUTHOR]

Quantitative differences in calcium and phosphorus metabolism between domestic species exist and can be visualised using data on calcium and phosphorus intake and faecal excretion. The parameter for analysing the results was defined as Δ = dietary calcium/phosphorus (Ca/P) ratio – faecal Ca/P ratio. In previous studies, hindgut fermenters had significantly higher Δ values than ruminants (sheep, cattle, goats), which was explained by the high calcium digestibilities in hindgut fermenters in contrast to highly efficient phosphorus recycling in ruminants. The first hypothesis of the present study was that different types of ruminants (grazer, browser, intermediate feeder) would show differences in Δ as a proxy for quantitative calcium and phosphorus metabolism. The second hypothesis was that camelids as functional, but not taxonomic ruminants would show Δ values similar to ruminants. We used herbivorous zoo animals (17 species, hindgut and foregut fermenters), which were kept on their regular diet without variation for 1 week. Then, faecal samples were obtained from the individual animals. Feed items and faecal samples were analysed for calcium and phosphorus, and dietary and faecal Ca/P ratios as well as Δ were calculated. A comparison of the species groups (one‐way ANOVA on ranks, p < 0.05) showed that zoo hindgut fermenters had significantly higher Δ values (0.67 ± 0.34) than camelids and zoo ruminants (–1.07 ± 0.35 and –1.87 ± 1.56). There was no significant difference between camelids, grazers (–1.49 ± 1.31), browsers (–1.63 ± 0.88) and intermediate feeders (–2.11 ± 1.76). The ruminant species from this study had markedly lower Δ than domestic ruminants from literature data. Especially intermediate feeders had low Δ, possibly due to more efficient phosphorus recycling than the domestic ruminants. [ABSTRACT FROM AUTHOR]

Chymotrypsin in crustaceans is an enzyme whose importance has not been fully recognized over time, despite being a fundamental component in the digestion of proteins in their food. Enzymes are basic catalytic components of cellular metabolism; of great diversity classified according to the function they exert (hydrolysis, oxidation-reduction, synthesis, isomerization, among others). Chymotrypsin belongs to the hydrolyses, which catalyzes the breaking of peptide bonds adjacent to the carboxyl groups of the aromatic amino acids tryptophan, tyrosine and phenylalanine. Since the 1980s there have been few studies related to this enzyme in crustaceans, concentrating a third of these (13 studies) in the last five years. Therefore, the paper aims to present a review about the existing information on these enzymes in crustaceans from a general perspective, helping to identify areas of opportunity to expand the knowledge of their function and properties in these invertebrates, as well such as the ecological, ethological, management, feeding and nutrition implications of aquaculture. [ABSTRACT FROM AUTHOR]

A total of 72 male Ross 308 broilers were reared to day 34 on a standard wheat and soy-based diet and then offered one of the four semisynthetic experimental diets, comprising two different soybean meal sources either without or with exogenous protease (treatments therefore offered in a 2*2 factorial arrangement). Each experimental diet was fed to 18 individually housed birds from 34 to 37 D after which ileal digesta were collected and digestibility coefficients were calculated. The two soybean meal sources were found to be nutritionally divergent (P

Differences in how individuals cope with stressful conditions (e.g. novel/unfamiliar environment, social isolation and increases in human contact) can explain the variability in data collection from nutrient digestibility trials. We used the collared peccary (Pecari tajacu), which is under process of domestication and shows high individual behavioral distinctiveness in reactions toward humans, to test the hypothesis that behavioral differences play a role in nutrient digestibility. We assessed the individual behavioral traits of 24 adult male collared peccaries using both the ‘behavioral coding’ and the ‘subjective ratings’ approaches. For the behavioral coding assessment, we recorded the hourly frequency of behaviors potentially indicative of stress during the 30-day habituation period to the experimental housing conditions. The subjective ratings were performed based on the individuals’ reactions to three short-term challenge tests (novel environment, novel object and threat from a capture net) over a period of 56 days. During the last 26 days, the collared peccaries were fed diets either high (n = 12) or low (n = 12) in dietary fiber levels, and we determined the total tract apparent digestibility of nutrients. The individual subjective ratings showed consistency in the correlated measures of ‘relaxedness’, ‘quietness’ and ‘satisfaction’ across the three challenge tests, which were combined to produce z score ratings of one derived variable (‘calmness’). Individual frequency of BPIS/h and calmness scores were negatively correlated and both predicted the total tract digestibility of acid detergent fiber (ADF), which ranged from 0.41 to 0.79. The greater the calmness z scores (i.e. calmer individuals), the greater the total tract digestibility of ADF. In contrast, the higher the frequency of BPIS/h, the lower the total tract digestibility of ADF. Therefore, our results provide evidence that by selecting calmer collared peccaries, there will be an increase in their capacity to digest dietary fiber.

Mullets (Mugilidae) present significant potential for sustainable aquaculture diversification due to their eurythermal, euryhaline, and low-trophic nature. However, the physiological differences and optimal cultured conditions among the diverse mullet species are quite unknown. For these reasons, the present study aimed to address two main objectives: (1) to characterize the differences in digestive biochemistry, somatic indexes, and body composition between two mullet species (Liza aurata and Chelon labrosus); and (2) to evaluate the interactions of two different feeding frequencies (one against three meals per day) on the above-mentioned parameters, and also on the potential bioavailability of nutrients determined using in vitro assays. The results evidenced higher protease and amylase activities for Chelon labrosus than for Liza aurata, while the latter species presented a higher percentage of eviscerated weight and muscle lipids. Furthermore, the results from in vitro assays supported the higher enzyme activity of Chelon labrosus by an observed increase in the release of amino acids and reducing sugars measured for this species. Regarding feeding patterns, the results of the in vitro assays simulating enzyme: substrate (E:S) ratios corresponding to one or three meals per day point to a clear increase of nutrient bioavailability when the daily ration is split into several meals. The present results improve the physiological knowledge of mullet species and define criteria to develop better management protocols by producers.

In the present study, the digestive enzyme activity during larval development in L. peru reared under intensive culture conditions was evaluated. The results revealed that L. peru larvae have the necessary enzymes to digest proteins, lipids and carbohydrates when nutritional reserves have been depleted at the onset of the exogenous feeding at 3 days after hatching (DAH) or 78 degree‐days (DD). The activities of the digestive enzymes follow patterns similar to those previously reported in other related species. As in other marine fish larvae, the amylase specific activity decreased during larval development of L. peru. At 25 DAH (650 DD), the specific activities of lipase, alkaline phosphatase and acid phosphatase declined, while the specific activities of pepsin, trypsin and chymotrypsin increased. In contrast, the individual activity of all enzymes steadily increased with development. The time required to reach the maximum activity varies, suggesting a relative importance of different digestive enzymes during the different developmental stages of the digestive tract. In our study, the highest activity was reached by amylase at Stage I and early Stage II (3–11 DAH or 78–286 DD), by lipase and both acid and alkaline phosphatases at the end of Stage II (18–22 DAH or 468–572 DD), and by trypsin, chymotrypsin and acid protease at Stage III (25 DAH or 650 DD). This study provides new data on the digestive physiology of larval L. peru that are particularly pertinent to early weaning and nutritional physiology, and that may be useful in the larval culture of this species. [ABSTRACT FROM AUTHOR]

The current study was conducted to investigate the influence of short-term feeding of test diets during metabolizable energy assays on growth performance, nutrient utilization, jejunal histomorphology, cecal short-chain fatty acids, and nutrient transporters in broilers. One hundred twenty-six broiler chickens were assigned to six treatments, each with seven replicates. Experimental diets were fed between days 14 and 21. Treatments included a corn–soybean meal reference diet and five test diets with low-protein soybean meal (LPSBM), wheat bran, soy hull, corn gluten feed, or rice bran. Birds were weighed on days 14 and 21; excreta, cecal content, and jejunal tissues were collected on day 21. Seven-day weight gain was highest (p < 0.01) for birds receiving the reference diet or LPSBM, whereas FCR was lowest (p < 0.05) for birds receiving the soy hull diet. Cecal acetate and total short-chain fatty acids were higher (p < 0.05) for wheat bran compared with the soy hull test diet. Jejunal villi were longer (p < 0.05) for chickens receiving the reference diet or LPSBM test diet. Glucose transporter (GLUT1) mRNA was greater (p < 0.05) in broilers receiving rice bran compared with soy hull test diets. Therefore, when reporting energy assays, it is important that indicators of animal growth or gut health be included to help contextualize energy utilization.

Tropical gar, Atractosteus tropicus Gill, 1863, is an ancient freshwater fish that is commercially cultivated in southern Mexico. Currently, there is a specific diet for its culture; however, the addition of probiotics has not been investigated. The objective of this study was to evaluate the supplementation of live yeast Debaryomyces hansenii for A. tropicus juveniles on growth, productive parameters, survival, somatic index, digestive enzyme activity, and immune system gene expressions (interleukin 10, il-10, Transforming growth factor ß1, tgf-ß1, and ß2 microglobulin, b2m). Three experimental diets increased the dose of live yeast (0.5, 1.0, and 1.5%; 1014, 1015, and 1016 CFU g diet-1, respectively) and a control diet (CD; without yeast) were designed. Daily weight gain and specific growth rate were higher in fish fed with CD and 0.5% D. hansenii. High activities of trypsin, chymotrypsin LAP, and α-amylase, as well as overexpression of il-10 in the spleen, were detected in fish feed 0.5% D. hansenii. The inclusion of D. hansenii had no positive effect on aquaculture for A. tropicus, lower doses should be tested to optimize the diet. [ABSTRACT FROM AUTHOR]

Avian herbivores face the exceptional challenge of digesting recalcitrant plant material while under the selective pressure to reduce gut mass as an adaptation for flight. One mechanism by which avian herbivores may overcome this challenge is to maintain high activities of intestinal enzymes that facilitate the digestion and absorption of nutrients. However, previous studies in herbivorous animals provide equivocal evidence as to how activities of digestive enzymes may be adapted to herbivorous diets. For example, "rate-maximizing" herbivores generally exhibit rapid digesta transit times and high activities of digestive enzymes. Conversely, "yield-maximizing" herbivores utilize long gut retention times and express lower activities of digestive enzymes. Here, we investigated the activities of digestive enzymes (maltase, sucrase, aminopeptidase-N) in the guts of herbivorous grouse (Aves: Tetraoninae) and compared them to activities measured in several other avian species. We found that several grouse species exhibit activities of enzymes that are dramatically lower than those measured in other birds. We propose that grouse may use a "yield-maximizing" strategy of digestion, which is characterized by relatively long gut retention times and generally lower enzyme activities. These low activities of intestinal digestive enzyme could have ecological and evolutionary consequences, as grouse regularly consume plants with compounds known to inhibit digestive enzymes. However, more comprehensive studies on passage rates, digestibility, and microbial contributions will be necessary to understand the full process of digestion in herbivorous birds. [ABSTRACT FROM AUTHOR]