Feeding habits and ontogenic changes in digestive enzyme patterns in five freshwater teleosts

Morphofunctional analysis of the gastrointestinal tract of an annual killifish: In search of structural traits related to the annual life history

Annual killifishes have active and voracious rates in acquisition of food resources with display of behaviors that allow them to maintain high metabolic rates to deal with the harsh and unpredictable conditions prevalent in temporary pools where they inhabit. The objective of this research was to describe histologically and ultrastructurally, the digestive system of the annual killifish Millerichthys robustus to identify morphological traits related to its annual life history and digestive physiology. Also, we quantify food items along the intestine as a proxy for rates of digestion. Millerichthys has a short digestive system, associated with a carnivorous diet, with no evidence of a stomach. Instead, the presence of pharyngeal jaws with caniform teeth was documented, related to the breakdown of invertebrate exoskeletons, allowing prey fluids to be tasted by taste corpuscles related to selection of food items, and that digestive enzymes penetrate once in the intestine. The histological morphology of the intestine showed four different regions, associated with its digestive rates: (i) reception of food from the esophagus with intact pray; (ii) digestion with enzymes from the pancreas and liver/gallbladder of simple exoskeleton prey (Entognatha), and beginning of absorption; (iii) absorption of nutrients, and digestion of large-complex exoskeleton prey (Hexanauplia, Brachiopoda, and Ostracoda); and (iv) probable absorption of intact macromolecules. The second region of the intestine presented two anatomical loops and the highest thickness that may be related to reducing the speed of food transit, allowing for more efficient digestion given the large amount of food ingested by this species.

Neuropeptide Y receptor Y8b (npy8br) regulates feeding and digestion in Japanese medaka (Oryzias latipes) larvae: evidence from gene knockout

Neuropeptide Y receptor Y8 (NPY8R) is a fish-specific receptor with two subtypes, NPY8AR and NPY8BR. Changes in expression levels during physiological processes or in vivo regulation after ventricular injection suggest that NPY8BR plays an important role in feeding regulation; this has been found in only a few fish, at present. In order to better understand the physiological function of npy8br, especially in digestion, we used clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology to generate npy8br-/- Japanese medaka (Oryzias latipes). We found that the deletion of npy8br in medaka larvae affected their feeding and digestion ability, ultimately affecting their growth. Specifically, npy8br deficiency in medaka larvae resulted in decreased feed intake and decreased expression levels of orexigenic genes (npy and agrp). npy8br-/- medaka larvae fed for 10 d (10th day of feeding) still had incompletely digested brine shrimp (Artemia nauplii) in the digestive tract 8 h after feeding, the messenger RNA (mRNA) expression levels of digestion-related genes (amy, lpl, ctra, and ctrb) were significantly decreased, and the activity of amylase, trypsin, and lipase also significantly decreased. The deletion of npy8br in medaka larvae inhibited the growth and significantly decreased the expression of growth-related genes (gh and igf1). Hematoxylin and eosin (H&E) sections of intestinal tissue showed that npy8br-/- medaka larvae had damaged intestine, thinned intestinal wall, and shortened intestinal villi. So far, this is the first npy8br gene knockout model established in fish and the first demonstration that npy8br plays an important role in digestion.

Ontogeny of the digestive enzyme activity of the pikeperch (Sander lucioperca) under culture condition

The pikeperch (Sander lucioperca) is a species with a high potential for aquaculture and a valuable food with high market acceptance. The aim of the study was to evaluate the functional ontogeny of digestive enzyme of pikeperch from hatching to 45 days-post fertilization, 777 degree-day (DPF, dd) under culture condition. The average total length (TL) of larvae measured at hatching was 3.6 ± 0.4 mm (5 DPF; 67 dd) and at the end of experiment (45 DPF, 777 dd) was 27.1 ± 1.1 mm. The survival rate was 80-90% during the experiment period. Inhibition zimography reveals the presence of nine bands with proteolytic activity in the digestive tract of juvenile pikeperch. Zimography results during the ontogeny revealed that in larvae at 8 DPF (108 dd) and 13 DPF (189 dd), three bands were presented. The variations observed in the enzymatic activity reflected a high amount of total protease activity at 10 DPF (133.5 dd). Regarding pepsin, its activity was observed for the first time at 26 DPF (378.9 dd). Lipase activity remained constant from hatching to 26 DPF (378.9 dd). The highest amount of α-amylase activity was detected at 15 DPF (211.5 dd) and 45 DPF (777 dd). The low lipase enzyme activity suggested that live feeds with low lipid were more suitable than diets containing high lipid levels; larvae had also early capability to digest nutrient-dense diet that was high in protein. According to results the pikeperch larvae possess after the exogenous feeding, a functional digestive system with high activities that indicated the gradual development of the digestive system.

Enzymatic, skeletal, and histological ontogeny of shi drum (Umbrina cirrosa) larvae under intensive culture conditions

This study was conducted to investigate the structural and ontogenetic development of the skeletal system and digestive tract histologically and enzymatically in larvae of shi drum (U. cirrosa) under intensive rearing conditions until 40 days after hatching (DAH). Among digestive enzymes, amylase was detected at 0.89 ± 0.12 mU mg protein^-1 on the first hatching day. The specific activities of trypsin and lipase were detected simultaneously with mouth opening on 3 DAH with 28.47 ± 3.52 and 2.8 ± 0.32 mU mg protein^-1, respectively. In addition, pepsin was found for the first time at 0.88 ± 0.21 mU mg protein^-1 on 15 DAH in association with stomach formation and increased sharply up to 40 DAH. In the structural development of the skeletal system, the development of the caudal fin in larvae was morphologically associated with the flexion of the notochord. It was observed that the shape of the fin and spine, which reached 40 DAH, became similar to the adult shape. Histologically, 3 DAH, the mouth and anus were opened. The formation of the primitive stomach was observed at the end of the seventh day-the pyloric sphincter formed between 13 and 18 days. A functional stomach was seen on the 15th DAH. Therefore, U. cirrosa is believed to have critical aquaculture potential that can be cultured under intensive conditions. The developmental profile of skeletal, enzymatic, and histological ontogeny observed in U. cirrosa is similar to that described for other sciaenid species.

Effects of autochthonous strains mixture on gut microbiota and metabolic profile in cobia (Rachycentron canadum)

The fish immune system is a topic or subject that offers a unique understanding of defensive system evolution in vertebrate heredity. While gut microbiota plays several roles in fish: well-being, promoting health and growth, resistance to bacterial invasion, regulation of energy absorption, and lipid metabolism. However, studies on fish gut microbiota face practical challenges due to the large number of fish varieties, fluctuating environmental conditions, and differences in feeding habits. This study was carried out to evaluate the impacts of supplemented three autochthonous strains, Bacillus sp. RCS1, Pantoea agglomerans RCS2, and Bacillus cereus RCS3 mixture diet on cobia fish (Rachycentron canadum). Also, chromatography, mass spectrometry and high throughput sequencing were combined to explore composition and metabolite profile of gut microbiota in juvenile cobia fed with supplemented diet. In the trial group, juvenile cobia received diets supplemented with 1 × 10¹² CFU mL^-1 autochthonous strains for ten weeks and a control diet without supplementation. Juvenile cobia receiving diets supplementation exhibited significantly improved growth than those without additives (control). Haematological indices, such as red blood cells, white blood cells, corpuscular haemoglobin concentration, mean corpuscular volume, haemoglobin, and mean corpuscular haemoglobin, were higher in the supplemented group. Similarly, digestive enzymes (trypsin, lipase, amylase, pepsin and cellulose, activities) activities were higher in supplemented diet with an indigenous isolates mixture. Serum biochemical parameters albumin, globulin, and total protein were significantly higher, while triglyceride, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and cholesterol showed no significant difference. On the other hand, glucose was significantly (P < 0.05) higher in the group without supplementation. On gene expression in the midgut, Immunoglobulin, Colony-stimulating factor receptor 1, major histocompatibility complex 1 were up-regulated by native isolates while T cell receptor beta, and Major histocompatibility complex 2 showed no significant difference. Gut bacterial composition was altered in fish receiving supplemented diet with autochthonous strains. Metabolomics also revealed that some metabolic pathways were considerably enriched in fish fed with supplemented diet; pathway analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment revealed that differentially expressed metabolites were involved in galactose metabolism, tryptophan metabolism, carbohydrate digestion and absorption, purine metabolism, and ABC transporters. Functional analysis of bacterial community showed that differences in enriched metabolic pathways generally comprised carbohydrate and its metabolites, nucleotide and its metabolites, amino acid and its metabolites, heterocyclic compounds, and tryptamines, cholines, pigments. The current investigation results showed that autochthonous strains mixture has significantly enhanced the growth, survival, and innate and adaptive immunities of juvenile cobia.

Feeding regimes affected the circadian rhythms of pancreatic digestive enzymes and somatic growth in flathead grey mullet (Mugil cephalus) fry

The effect of different feeding regimes on the circadian rhythms of pancreatic digestive enzyme activities was evaluated in Mugil cephalus fry weighting 0.34 ± 0.01 g. Feeding regimes (feeding ration = 3% stocked biomass) differed on the number of meals offered per day: one, two and ten meals per day (R1, R2 and R3, respectively). The number of meals per day affected somatic growth; in particular, fry from the R3 group (0.80 ± 0.01 g) grew better than their congeners from R2 (0.70 ± 0.01 g) and R1 (0.63 ± 0.01 g) groups (P < 0.05). Feeding behaviour was modulated by the feeding regime, being the maximal gut fullness values found just after meal distribution in R1 and R2 groups, whereas this trend was not observed when feed was offered continuously during light hours (R3). Fry from R1 and R2 groups showed hyperphagia as they tended to store in their gut as much as possible feed particles to be later digested due to the limited daily meals. This strategy negatively affected feed digestion due to inappropriate enzyme to substrate ratio, changes in digestive enzyme activities and chyme transit times, which ultimately impaired growth performance. Enzyme activities were modulated by the number of meals, the more frequent the meals offered, the lower enzyme activities, supporting the hypothesis that digestive function is adapted to obtain a maximum benefit of the ingested nutrients. Present results showed that feeding grey mullet fry continuously during day light hours optimized feed digestion and promoted fry growth.

Effects of probiotics on digestive enzymes of fish (finfish and shellfish); status and prospects: a mini review

Digestive enzymes are found in the digestive tract of animals which assist in the breakdown of larger food molecules into more easily absorbed particles that can then be used by the body. The ability of fish to break down a diet is highly dependent on the availability of suitable digestive enzymes which mediate specific degradation pathways and on both the physical and chemical nature of food. Probiotics are known to produce helpful enzymes that aid in digestion and protect the gastrointestinal tract (GIT) of animals. When applied appropriately, probiotics improve intestinal microbial balance which also improves digestive enzyme activities, food absorption, and decrease pathogenic issues in the GIT. They work hand-in-hand with the digestive enzymes in the GIT of animals as supplements thereby improvings nutrition. This in turn leads to higher feed efficiency and growth as well as the prevention of antinutritional factors present in the ingredients, intestinal disorders, and pre-digestion. This review seeks to present summaries of the results of research findings on the application of probiotics on the activities of digestive enzymes including amylase, lipase, and protease. Further, this review points out gaps in available literature and suggests ideas that could be explored in further investigations to better understand and enhance the activities of these digestive enzymes to increase feed and nutrient utilization and the production of aquaculture species.

Characterization and comparison of the digestive physiology of two scombrids, Katsuwonus pelamis and Sarda sarda, in the Gulf of Cádiz

Fish and other marine animals have a unique and intimate interaction with their surrounding environment. Diet type or trophic level play significant roles in modulating species digestive physiology. However, little is known about how the trophic niche influences digestive activity and gut microbiota in scombrids species. The aim of the present study was to analyse and describe the digestive physiology of the skipjack tuna (Katsuwonus pelamis) and the Atlantic bonito (Sarda sarda) as bioindicator of the feeding ecology and trophic niche for both species in the Gulf of Cádiz (Spain). For that, fish proximate composition, pH of digestive organs and digestive enzymes activity levels were analysed in 10 individuals of each species to gain insight into the digestive physiological adaptations of the two species of scombrids. In addition, intestinal microbiota composition was determined for the skipjack tuna. The integration of the results suggested a clear trophic niche segregation between both species. Stomach pH was associated in both species with infrequent feeding events. Body proximate composition and digestive lipases activity patterns pointed to a high predominance of lipids in the Atlantic bonito diet, suggesting oily fish as main prey. On the other hand, results supported the skipjack tuna as a highly opportunistic feeder with a more varied diet, including fish but also crustaceans as preys. The gut microbial community in the latter species is dominated by Firmicutes and Tenericutes at phylum level, and by Mycoplasma, Blautia and Dorea at genus level. The present study contributes to advance the knowledge on the feeding behaviour and physiology diversity in fish species as a result of adaptation to a particular habitat.

The onset of piscivory in a freshwater fish species: analysis of behavioural and physiological traits

The onset of piscivory in fish, resulting in a shift from zooplankton or invertebrate to fish prey, was studied on pikeperch (Sander lucioperca) larvae displaying and not displaying piscivorous behaviour at different ages (23, 30, 37, 44 and 52 days post-hatching) using behavioural (attack, capture and swimming activity), morphological (allometry) and digestive enzymatic (trypsin, α-amylase and pepsin) analyses. The shift from zooplanktonic food items (Artemia nauplii) to a piscivorous diet did not occur at the same time for all individuals within the same cohort. Predation tests, conducted under controlled conditions (20°C; ad libitum feeding), showed that some larvae attacked fish prey as early as the age of 3 weeks [11.0 ± 1.3 mm total length (TL)], whereas others did not start until the age of 6 weeks (16.6 ± 1.9 mm TL). Piscivorous individuals were bigger, with larger heads, longer tails, higher acid protease and lower alkaline protease activities, than non-piscivorous conspecifics. In conclusion, high interindividual variability in morphological and digestive system developments linked to the development of predatory abilities could induce cannibalism in fish.

Ontogeny of Expression and Activity of Digestive Enzymes and Establishment of gh/igf1 Axis in the Omnivorous Fish Chelon labrosus

Simple Summary

Thick-lipped grey mullet (Chelon labrosus) feeds on the lowest trophic levels during adult stages, for which it is considered a viable candidate for an economically and environmentally sustainable aquaculture. Similar to most of marine fish species, C. labrosus produce a large number of eggs, leading to morphologically and anatomically larvae that are not completely mature and have to pass through substantial differentiation and development in their functional systems to acquire adult features. Therefore, the study of the development of digestive tract and of the growth regulation can provide useful information to adapt the feeding protocols and rearing conditions to the physiological requirements at each stage. This work aimed to evaluate the early ontogeny of key digestive enzymes and somatotropic factors at biochemical and/or transcriptional levels. Our results evidenced that maturation of the digestive system and acquisition of the adult mode of digestion occurs around 60 to 70 days post hatch (dph), when starch or other low-cost carbohydrate-based compounds could be used in formulated diets at increasing levels. Furthermore, our results implied an independent expression of the studied somatotropic genes during the first 40 dph and establishment of a functional growth hormone/insulin-like growth factor 1 axis from 50 dph onward.

Abstract

Thick-lipped grey mullet (Chelon labrosus) is a candidate for sustainable aquaculture due to its omnivorous/detritivorous feeding habit. This work aimed to evaluate its digestive and growth potentials from larval to early juvenile stages. To attain these objectives the activity of key digestive enzymes was measured from three until 90 days post hatch (dph). Expression of genes involved in digestion of proteins (try2, ctr, pga2, and atp4a), carbohydrates (amy2a), and lipids (cel and pla2g1b), together with two somatotropic factors (gh and igf1) were also quantified. No chymotrypsin or pepsin activities were detected. While specific activity of trypsin and lipase were high during the first 30 dph and declined afterward, amylase activity was low until 57 dph and increased significantly beyond that point. Expression of try2, ctr, amy2a, and cel increased continuously along development, and showed a peak at the end of metamorphosis. Expression of pla2g1b, pga2 and atp4a increased until the middle of metamorphosis and decreased afterwars. Most of these trends contrast the usual patterns in carnivorous species and highlight the transition from larvae, with high protein requirements, to post-larvae/juvenile stages, with omnivorous/detritivorous feeding preferences. Somatotropic genes, gh and igf1, showed approximately inverse expression patterns, suggesting the establishment of the Gh/Igf1 axis from 50 dph.

Composition of the microbial communities in the gastrointestinal tract of perch (Perca fluviatilis L. 1758) and cestodes parasitizing the perch digestive tract

Using the approach of sequencing the V3-V4 region of the 16S rRNA gene, we have analysed the bacterial diversity associated with the distinct compartments of the gastrointestinal tract of perch (Perca fluviatilis) and cestodes (Proteocephalus sp.) parasitizing their digestive tract. The dominant microbiota associated with cestodes (Proteocephalus sp.) was represented by bacteria from the genera Serratia, Pseudomonas and Mycoplasma. By comparing the associated microbiota of perch and cestodes, a clear difference in bacterial composition and diversity was revealed between the community from the stomach content and other parts of the gastrointestinal tract of fish. Microbiota associated with cestodes was not significantly different in comparison with microbiota of different subcompartments of perch (mucosa and content of intestine and pyloric caeca) (ADONIS, p > .05) excluding microbiota of stomach content (ADONIS, p ≤ .05). PICRUSt-based functional assessments of the microbial communities of perch and cestodes indicated that they mainly linked in terms of metabolism and environmental information processing and could play an important role in the nutrition and health of host.

Activity of proteolytic enzymes in the intestine of bream Abramis brama infected with cestodes Caryophyllaeus laticeps (Cestoda, Caryophyllidea)

Adaptive mechanisms underlying the long-term existence of intestinal parasites in their enzymatically hostile environment are still poorly understood, particularly with regard to fish cestodes. The study describes the activity distribution of proteolytic enzymes along the gut of the bream Abramis brama infected with intestinal cestodes Caryophyllaeus laticeps and characterizes the capacity of these worms to inhibit host proteinase activity. Mucosal proteolytic activity was mainly presented by serine proteinases. The research revealed an insignificant increase in total proteolytic activity from anterior and middle to posterior part of the gut accompanied with changes in proportions of various proteinase subclasses along the intestine. The trypsin (but not chymotrypsin) activity in the posterior section was significantly higher than in the mid-section. Both the incubation medium of the worms and their extract had a significant inhibitory effect on mucosal proteolytic activity and commercial trypsin samples. In both instances, the effect was comparable with that of a synthetic serine protease inhibitor, PMSF. SDS-PAGE electrophoregrams of the incubation medium of C. laticeps and its extract revealed three common protein bands, with apparent molecular masses from 19 to 47 kDa, possibly responsible for the worms' inhibitory capacities. According to casein-zymography performed, the target host proteinases for a putative cestode inhibitor (inhibitors) have an approximate molecular weight of 28-53 kDa. A comparative test with the extracts from three other cestodes showed that each of them can suppress the proteolytic activity of the bream mucosa. The level of inhibitory activity was found to increase with protein content in the extracts of these tapeworms.

A review on the application of Bacillus as probiotics in aquaculture

Probiotics use in aquaculture has gained attention as microbial candidates to maintain the health and the well-being of many aquaculture animals. Among the many microbial candidates, probiotic Bacillus has sporulation capacity that makes them survive harsh environmental conditions, are non-pathogenic and non-toxic when fed to fish, and can produce antimicrobial substances making them more suitable candidates compared to other probiotics. In this review, we discussed the necessity of using the probiotic Bacillus in sustainable aquaculture as a good alternative to improve feed utilization, stress response, immune response and disease resistance, maintenance of tissue integrity, and as well improvement of water quality for sustainable aquaculture. Therefore the findings of current researches about the effects of Bacillus application to improve the culture of aquatic animals for future research and development of Bacillus application in aquaculture have been summarised.

Comprehensive approach to restoring urban recreational reservoirs. Part 2 - Use of zooplankton as indicators for the ecological quality assessment

The presented research is part of the LIFE project ("EH-REK" LIFE08 ENV/PL/000517) on innovative restoration methods for small urban impoundments in the city of Łódź (Poland). The objective was to evaluate the usefulness of zooplankton as a biological quality element, when assessing the effectiveness of restoration efforts in three urban reservoirs and a one pond. The fifth unrestored pond was used as an example of the progressive eutrophication of an urban ecosystem. Studies were conducted during two periods: before (2010-2012) and after (2013-2016) restoration. A selection of zooplankton indices, including the rotifer trophic state index (TSI_ROT), was used. The influence of the supplying river resulted in the negligible responses of biological parameters to the restoration efforts in the Upper Arturówek (UA) reservoir, which is the first in cascade of reservoirs. However, clear symptoms of water quality improvements were observed in the other two reservoirs (the Middle Arturówek, MA; the Lower Arturówek, LA) and in the Bzura-17 (B17) pond. After restoration, the contribution of species indicative of high trophic levels decreased in these ecosystems. The TSI_ROT was strongly positively correlated with the trophic state index based on chlorophyll a, and both parameters significantly decreased in the MA, LA and B17. In the unrestored pond (B11), the successive increase in the concentrations of chemical parameters indicated progressing eutrophication. Interestingly, since 2013, the TSI_ROT values clearly decreased in B11, but the strong negative correlation between ammonium concentration and rotifer density indicated that the reduced TSI_ROT values didn't result from improvements in water quality; rather, they resulted from the increases in pollution and the associated harmful impacts on Rotifera. In conclusion, the TSI_ROT can be a useful tool for assessing the ecological quality of small urban ecosystems; however, the use of biological indices must be supported by also monitoring physicochemical parameters.

Diet and other environmental factors shape the bacterial communities of fish gut in an eutrophic lake

AIMS

The aim of this work was to study the gut microbial diversity from eight species of wild fish with different feeding habits, digestive physiology (gastric vs agastric) and provide comparative structural analysis of the microbial communities within their environment (food items, water, sediments and macrophytes).

METHODS AND RESULTS

The microbiota of fish gut and their prey items were studied using next generation high-throughput sequencing of the 16S ribosomal RNA genes. A scatter plot based on PCoA scores demonstrated the microbiota formed three groups: (i) stomach and intestinal mucosa (IM), (ii) stomach and intestinal content (IC), and (iii) prey and environment. Comparisons using ANOSIM showed significant differences among IC of omnivorous, zoobenthivorous, zooplanktivorous-piscivorous fishes (P ≤ 0·1). No significant difference was detected for mucosa from the same groups (P > 0·1).

CONCLUSIONS

Neither the interspecies differences in fish diet nor their phylogenetic position had any effect on the microbiome of the IM, but diet did influence the composition of the microbiota of the IC.

SIGNIFICANCE AND IMPACT OF THE STUDY

The data demonstrate that fish harboured specific groups of bacteria that do not completely reflect the microbiota of the environment or prey.

Composition of gastrointestinal content, protease and lipase activities in summer and winter of four freshwater siluriforms (Teleostei: Actinopterygii) with two different feeding habits

The aim of this study was to determine the composition of gastrointestinal content and protease and lipase activities in summer and winter as well as to evaluate the relationship between digestive enzyme activity and centesimal composition of gastrointestinal content and feeding habits of two omnivorous species, Rhamdiaquelen (Quoy &amp; Gaimard, 1824) and Pimelodusmaculatus (LaCèpede, 1803), and of two detritivorous species, Loricariichthysanus (Valenciennes, 1835) and Hypostomuscommersoni (Valenciennes, 1836). The activities of pepsin, trypsin, chymotrypsin, and lipase, and the levels of proteins and lipids in the gastrointestinal tract, were evaluated. The enzyme activities were not related to the centesimal composition of gastrointestinal content or feeding habits. This finding could be associated with the variations of nutrient availability over time in the environment, as was observed in the centesimal composition of food ingested by the fish in summer and winter. The analyzed enzymes exhibited a constitutive character in these species; that is, the digestive enzymes are always available in the gastrointestinal tract to digest any food that the fish may find as an adaptation to better utilize the nutrients available in the environment in winter and summer.

Influence of time, storage temperature and freeze/thaw cycles on the activity of digestive enzymes from gilthead sea bream (Sparus aurata)

In this study, we tested the effects of long-term storage (2 years) at -20 °C and short-term storage (several hours) in ice and freeze/thaw cycles on the activities of pancreatic, gastric and intestinal (brush border and cytosolic) digestive enzymes in a teleost fish species. The results revealed a significant lose in activity of pancreatic (trypsin, chymotrypsin, total alkaline proteases and α-amylase) and intestinal cytosolic (leucine-alanine peptidase) enzymes between 140 and 270 days of storage at -20 °C, whereas in contrast, the activity of all the assayed brush border enzymes remained constant during the first 2 years of storage at -20 °C. During short-term storage conditions, the most stable enzymes assayed were those of the enterocytes of the brush border, which did not show any change in activity after being held for 5 h in ice. Five freezing and thawing cycles did not affect the activity of the intestinal brush border enzymes and the cytosolic ones, whereas the activity of trypsin, α-amylase and bile-salt-activated lipase was significantly affected by the number of freezing and thawing cycles. No changes in pepsin activity were found in samples exposed to 1 and 2 freezing and thawing cycles.