Digestive Enzyme Gene Expression Research Articles

Transcriptome analysis reveal the effect of freshwater sediments containing 2,3,7,8-tetrachlorodibenzo-p-dioxin on the Macrobrachium rosenbergii hepatopancreas, intestine, and muscle

This research evaluated the hepatopancreas, intestine, and muscle transcriptome alternation of Macrobrachium rosenbergii, and to confirm the relative glycerophospholipid, cytochrome P450 system, and fatty acid metabolism gene expression in sediments containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) of 60 ng/sediment (g) and 700 ng/sediment (g) for 90 days of culture.Transcriptome analysis revealed that the TCDD sediment affected the hepatopancreatic metabolism of xenobiotics in M. rosenbergii via the cytochrome P450 system, drug metabolism-other enzymes, drug metabolism-cytochrome P450, chemical carcinogenesis, and lysosome function. Intestinal analysis also showed a similar phenomenon, but this finding was not observed in the muscle tissue.qPCR analysis indicated that the expression levels of APTG4, LPGAT1, ACHE, GPX4, ECHS1, ATP5B, FABP, and ACC in the hepatopancreatic and intestinal tissues decreased, but those in the muscle tissues did not.In summary, TCDD sediment induced tissue metabolism, especially in the hepatopancreas and intestine. TCDD sediment mainly affected the digestive enzyme gene expression with concentration. These results indicated that the presence of TCDD in the sediment played a major role in the hepatopancreatic and intestinal metabolism system of M. rosenbergii.

Effects of In-Ovo Glucose and Glutamine Treatment on Hatching Efficiency, Intestinal Histomorphology and Gene Expression of Digestive Enzymes in Broiler Chicks

The purpose of the present study was to identify the effects of in-ovo injection of glucose and glutamine on hatching efficiency, hatching weight, liver and residual yolk weights, intestinal histomorphology and gene expressions of digestive enzymes. On the 17th day of incubation, NaCl (0.9 %), glutamine (0.5 ml 10%), glucose (0.5 ml 0.25 g/ml), and glutamine+glucose (0.25 ml 10%+0.25 ml 0.25 g/ml) were injected into the amniotic sac. In-ovo injection of glucose, glutamine and glucose+glutamine significantly decreased hatching efficiency in glucose and glutamin+glucose groups (p<0.001). This treatment did not affect hatching weight, liver and residual yolk weight in any of the groups. When the intestinal histomorphology was evaluated, in-ovo injection was found to increase the villi height/crypt depth ratio, villus width and the number of goblet cells in the jejunum; whereas villi height, crypt depth, and tunica muscularis thickness were not significantly affected by the treatments. Moreover, the ileum histomorphology in general appear not to be affected by any of the treatments as well. In-ovo glutamine injection significantly increased Suc-Iso and mTOR gene expressions (p≤0.05) compared to the control group, whereas SGLT1 gene expression was statistically indifferent. At the end of the study, while in-ovo glucose and glutamine injection had an overall negative effect on the hatching efficiency in broiler chicks.

When digestive physiology doesn't match “diet”: Lumpenus sagitta (Stichaeidae) is an “omnivore” with a carnivorous gut

What an animal ingests and what it digests can be different. Thus, we examined the nutritional physiology of Lumpenus sagitta, a member of the family Stichaeidae, to better understand whether it could digest algal components like its better studied algivorous relatives. Although L. sagitta ingests considerable algal content, we found little evidence of algal digestion. This fish species has a short gut that doesn't show positive allometry with body size, low amylolytic activity that actually decreases as the fish grow, no ontogenetic changes in digestive enzyme gene expression, elevated N-acetyl-glucosaminidase activity (indicative of chitin breakdown), and an enteric microbial community that is consistent with carnivory and differs from members of its family that consume and digest algae. Hence, we are left concluding that L. sagitta is not capable of digesting the algae it consumes, and instead, are likely targeting epibionts on the algae itself, and other invertebrates consumed with the algae. Our study expands the coverage of dietary and digestive information for the family Stichaeidae, which is becoming a model for fish digestive physiology and genomics, and shows the power of moving beyond gut content analyses to better understand what an animal can actually digest and use metabolically.

Effects of dietary Clostridium autoethanogenum protein on the growth, disease resistance, intestinal digestion, immunity and microbiota structure of Litopenaeus vannamei reared at different water salinities.

The shortage of fishmeal (FM) resources limits the healthy development of aquaculture. Developing new protein sources to replace FM in aquatic feeds is an effective measure to alleviate this situation. However, the application effect of new protein sources is greatly affected by water salinity, which is an important parameter of aquaculture. In this study, the growth, disease resistance, and intestinal digestion, immunity, and microbiota structure of Litopenaeus vannamei (initial weight: 0.38 ± 0.01 g) fed on Clostridium autoethanogenum protein (CAP) or not at three different water salinities (15 ‰, 30 ‰, and 45 ‰) were compared, aiming to explore the effects of dietary CAP on shrimp when suffering different salinity stresses. The results showed that the growth performance, feed utilization, and survival rate (SR) after pathogen challenge of L. vannamei could be significantly improved by dietary CAP when compared with the control at the same salinity and they were also significantly affected by salinity changes when L. vannamei was fed on the same protein source. With the increase in salinity, obvious upregulation was observed in the activities and gene expression of digestive enzymes both in L. vannamei fed on FM and CAP, with significantly higher levels in L. vannamei fed on CAP than in those fed on FM at the same salinity. Meanwhile, the expression levels of immune genes in the CAP group were significantly higher than those in the FM group at different salinities. The intestinal microbiota analysis showed that CAP could increase the relative abundance of beneficial bacteria and decrease the relative abundance of harmful bacteria in the intestine of L. vannamei at the phylum, family, and genus levels, and it was more affected by salinity changes when compared with FM. Besides, the changes in salinity and protein sources led to different changes in the intestinal microflora function of L. vannamei. In sum, this study indicated that CAP could improve the growth, disease resistance, digestive capacity, and intestinal microflora of L. vannamei with a much more intense immune response and enhance its ability to cope with salinity stress.

Zootechnical performance, biochemical composition and gene expression of digestive enzymes in Litopenaeus vannamei post‐larvae fed the nematode Panagrolaimus sp. ( NFS 24–5)

This study investigated the effect of different size ranges, densities and feeding frequencies of the nematode Panagrolaimus sp. strain NFS 24–5 on zootechnical performance, biochemical composition and digestive enzyme gene expression of Litopenaeus vannamei stage 1 (PL1) post-larvae. Trial 1 supplied large (LN) (800–1,200 μm) or small (SN) (200–800 μm) DHA-enriched nematodes twice daily, substituting non-enriched Artemia (control treatment) totally (100%) or partially (75%). Trial 2 only supplied LN once or thrice daily, replacing Artemia at 100% or 75%. Trial 1 larvae fed on LN (100LN and 75LN) showed similar zootechnical performance and biochemical composition to those reared with Artemia (100A). Supplying 100% SN negatively affected PL1 total length. LN contained twofold more arachidonic (ARA) and eicosapentaenoic acids than SN, and docosahexaenoic acid (DHA) was fivefold higher. Trial 2 obtained better zootechnical results with 75% Artemia substitution than 100%. Shrimp fatty acid profiles were similar in Trials 1 and 2. Post-larvae fed 100LN had twofold higher percentages of ARA and DHA compared with those from the control treatment. Amylase, lipase and chymotrypsin genes were over-expressed in PL1 fed 100LN once daily. Contrarily, amylase and trypsin genes were under-expressed in PL1 fed 100LN or 75LN thrice daily, evidencing a better nematode availability for shrimp. In conclusion, non-enriched Artemia can be partially or totally substituted by large DHA-enriched Panagrolaimus sp. during the larval stage of L. vannamei when the nematode is distributed twice daily.

The Discovery of Circadian Rhythm of Feeding Time on Digestive Enzymes Activity and Their Gene Expression in Sinonovacula constricta Within a Light/Dark Cycle

The circadian rhythm has a great impact on the growth, metabolism and development of animals, but little is known about the circadian rhythm of marine bivalves. Understanding of the feeding rhythm is of great significance to increase the yield of razor clam Sinonovacula constricta, an economically important bivalve mollusk. The aim of this experiment was to study the effects of circadian rhythm of feeding time on digestive enzymes activities and their gene expression in S. constricta within a light (ZT8-ZT20)/dark (ZT20-ZT8) cycle. The present results showed that circadian rhythm of feeding rate (FR) was highly associated with digestive enzyme activities and relative expression of their genes. The highest values of FR were basically observed in the night from ZT0-ZT2 and ZT6-ZT8, which were significantly higher than those values in the daytime from ZT12-ZT14 and ZT18-ZT20 (P < 0.05). The digestive enzymes activities displayed the highest values at ZT2 and ZT8, and the lowest at ZT14 and ZT20. Among them, cellulase and pepsin were found to have significantly different activities (P < 0.05), rather than amylase and lipase. Notably, the relative expression of digestive enzyme genes shared the similar pattern with the activities of digestive enzymes. The highest values of relative gene expression of amylase (AMY), lipase (LIP), cellulase (CEL), and pepsin (PEP) were found at ZT2 and ZT8 in the night, while the lowest values were found at ZT14 during the day. It is therefore suggested that the biological clock may regulate the process from feeding to digestion. Furthermore, it might be better to feed at night to reduce cultivating cost and increase economic benefits in the farming industry of S. constricta.

Ontogeny and diurnal patterns of molecular gene expression and activity of digestive enzymes in developing greater amberjack

The greater amberjack, Seriola dumerili, is a fast-growing pelagic teleost with great interest for the diversification of farmed marine fish species in the Mediterranean region. Aiming to advance the optimization of feeding during the early stage of this species, this study examines the ontogeny of digestive function using molecular and biochemical approaches. Gene expression of digestive enzyme precursors and the enzymatic activity have been determined during the first 51 days post hatching (dph) and during the diurnal period of 19 dph larvae reared in semi-intensive conditions. The expression of pancreatic proteases precursors (try3, ctra and ctrb1) increased from first-feeding, while gastric chitinase (chia1), gastric protease (pga3) and proton pump (atp4a2) after 10 dph. The expression of pancreatic lipases (cel1, cel2 and cel3) peaked between 6 and 10 dph, phospholipase A2 (pla2g1b) rose only after 25 dph, while α-amylase (amy2a) increased mainly from 20 dph. The trypsin activity was more evident from first-feeding to 25 dph and chymotrypsin activity from this day onwards. Acidic chitinase and pepsin activity appeared, respectively, at 16 and 30. The activity of 7C-like lipase was evident from first-feeding but as 4C-like lipase significantly increased from 15 dph, while amylase peaked from 6 to 22 dph. Aminopeptidase and alkaline phosphatase activities started at 20 dph indicating the functional maturation of brush border of the enterocytes. The daily pattern analysis showed a food anticipatory strategy in the expression of proteases related genes. Lipases activity was more evident during the morning hours, followed by amylase, and by alkaline proteases in the afternoon. Results, also, suggested an alternation in the activity of chymotrypsin and trypsin. These ontogenetic patterns are concordant with a carnivorous marine teleost.

Molecular aspects of lipid metabolism in the midgut gland of the brown shrimp Crangon crangon.

The brown shrimp, Crangon crangon, is well adapted to the variable environmental conditions in the southern North Sea. It is very abundant, has high reproduction rates, and holds a key position in coastal ecosystems. This species has very low lipid deposits in the midgut gland, suggesting that the main function of the midgut gland is metabolic turnover rather than energy storage. Based on seasonal gene expression studies and established transcriptome data, we investigated key components of lipid metabolic pathways. Gene expression of triacylglycerol lipase, phospholipase, and fatty acid desaturase were analyzed and compared with that of other digestive enzymes involved in lipid, carbohydrate, and protein catabolism. Our results suggest that gene expression of digestive enzymes involved in lipid metabolism is modulated by the lipid content in the midgut gland and is related to food availability. Brown shrimp seem to be capable of using cellular phospholipids during periods of food paucity but high energetic (lipid) requirements. Two of three isoforms of fatty acid binding proteins (FABPs) from the midgut gland involved in fatty acid transport showed specific mutations of the binding site. We hypothesize that the mutations in FABPs and deficiencies in anabolic pathways limit lipid storage capacities in the midgut gland of C. crangon. In turn, food utilization, including lipid catabolism, has to be efficient to fulfill the energetic requirements of brown shrimp.

Transcriptome Analysis Reveals Potential Genes Involved in Digestive Enzyme Function in a Mudflat Crab Helice tientsinensis

The mudflat crab (Helice tientsinensis) is one of the most common crabs along the coast of China, and it is one of the important commercial species in Chinese aquaculture. However, unlike other consumed crabs, which are omnivores or carnivores, H. tientsinensis is a primarily herbivorous crab. Studies have rarely been conducted on the expression of digestive enzyme genes and their role in regulating digestive capacity in this crab. Here, we applied the Illumina platform to sequence and de novo assembled a H. tientsinensis transcriptome dataset using mRNA from the hepatopancreas. A total of 50,730,758 clean reads were obtained and 399,653 unigenes were assembled. Among these unigenes, 36,221 unigenes had signifificant hits in the NR protein database. These unigenes were predicted to encode 127 carbohydrases, 107 peptidases and 9 lipases. We observed that the glucanases and amylases were most closely related to those found in other Decapoda species. RT-qPCR analysis showed that the expression of 6 digestive enzyme genes was higher in the hepatopancreas than those in other parts of the body. It is the first time to report various digestive enzyme genes in H. tientsinensis and to provide a better understanding about the physiological adaptation to primarily herbivorous diet.

Expression of Digestive Enzyme Genes in the Digestive Tract of the Two-spotted Cricket During Starvation

Expression of Digestive Enzyme Genes in the Digestive Tract of the Two-spotted Cricket During Starvation

Comparative transcriptome analysis reveals the expression and characterization of digestive enzyme genes in the hepatopancreas of the Chinese mitten crab

The Chinese mitten crab Eriocheir japonica sinensis is one of the most common aquaculture species cultivated in China. The crab is an omnivore, and its hepatopancreas absorbs and stores nutrients. The aim of this study was to elucidate the expressions of the digestive enzyme genes and determine their respective roles in regulating digestive capacity in E. j. sinensis. We sequenced the hepatopancreatic transcriptomes of crabs fed a meat diet (MD), a vegetarian diet (VD), or a mixed diet (MV) and compared the gene expression patterns of these three groups of crabs. A total of 305,887 unigenes were obtained, of which 8747, 10,963, and 8877 were significantly differentially expressed in the comparisons between the MD and MV, VD and MV, and MD and VD diets, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) database-based enrichment analysis revealed that the differentially expressed gene (DEG) responses in the hepatopancreases to the MD mainly involved the “pancreatic secretion,” “glutathione metabolism,” “sphingolipid metabolism,” “fatty acid metabolism,” and “glycerolipid metabolism pathways.” DEG responses to the VD based on KEGG analysis mainly involved the “galactose metabolism,” “starch and sucrose metabolism,” and “fructose and mannose metabolism” pathways. The key digestive enzymes, including trypsin, β-glucosidase, chitinase, and triacylglycerol lipase, were identified. Our results further our understanding of crustacean hepatopancreatic functions during food digestion and provide resources for further studies regarding the molecular basis of omnivorous diets in crustaceans.

Effects of low protein diets with amino acids supplementation on biochemical and faeces parameters in weaned piglets

Effects of low protein diets with amino acids supplementation on biochemical and faeces parameters in weaned piglets

Gene expression, enzyme activity and performance of Nile tilapia larvae fed with diets of different CP levels

Protein is the most costly nutrient in fish feed, and while diets offered in the early stages of development typically have high levels of CP, they do not always correspond to the real requirements of the animals. Thus, research that seeks to learn the true nutritional requirements of fish is fundamental to improving commercial fish culture. The present study evaluated the protein requirements of Nile tilapia (Oreochromis niloticus) under larviculture. Fish performance, gene expression for digestive enzymes and their enzymatic activity and stress response to air exposure were analyzed. Four experimental diets differing in CP level were formulated: 30%, 36%, 42% and 48%. Fish larvae were fed the experimental diets during development and sampled 10, 20 and 30 days after the beginning of the experiment for performance, gene expression and enzymatic activity. At sampling time 30, stress resistance was also evaluated by means of an air exposure test. At sampling time 10, CP levels between 36% and 48% could be used for a better performance. During this period, pepsinogen expression was greater for 30% CP, intermediate for 42% and lower for 36% and 48%. After this initial period, diets of between 30% and 42% CP are recommended for better performance. At sampling time 20, gene expression for digestive enzymes and their enzymatic activity were similar for all diets tested. At sampling time 30, the diet of 42% CP induced both greater pepsinogen expression and pepsin activity. Survival after the air exposure test after 30 days of feeding was influenced by CP level in the diet, with the highest survival being for fish fed with 36% CP. Taken together, the present results demonstrate that dietary CP influences digestive enzyme gene expression and activity, and suggest that the best CP levels for Nile tilapia larviculture vary depending on larval stage.

Gene expression of digestive enzymes during the initial ontogeny of Mexican snook Centropomus poeyi

Mexican snook ( Centropomus poeyi ) is one of the most important commercial species in Southeast Mexico, which has been overexploited by fisheries. For this reason, some recent studies related to its culture have been done. However, the basic biological knowledge of the digestive physiology is still unknown. In this study, the gene expression of trypsin, (TRY), bile-salt dependent lipase (BAL), amylase (AMY), and cytosolic non-specific dipeptidase (CNP) was investigated during the larval period from embryo (0 days after hatching, DAH), eleuteroembryo (1 DAH) until 25 DAH using RTq-PCR approach and was normalized with the elongation factor 1-α gene (EF1-α). TRY gene expression showed the maximum peak at 17 DAH; meanwhile, BAL gene expression showed variations during larviculture, however, three peaks were observed at 10, 17 and 25 DAH, which appears to correspond to changes in live food supply (rotifers and Artemia nauplii). AMY gene expression was low detected from hatching onwards and showed a slight peak at 10 DAH when larvae were fed with Artemia nauplii. Finally, CNP gene expression had presented three peaks at 2 DAH (yolksac absorption), 19 and 23 DAH when larvae were fed with Artemia nauplii. We conclude that C. poeyi larvae showed early and high digestive enzyme expressions, especially TRY, which indicate that could be possible to start the weaning process at 25 DAH, which could be shorter compared than other Centropomid species.

Comparison of Some Relative Gene Expressions in the Yolk Sac Membrane and Small Intestine of the Embryos in the Layer Hybrid and Pure Breeds

Pure breeds are important due to the fact that they adapt well to poor husbandry conditions. However, gene expression of digestive enzymes and nutrient transporters of pure breeds and layer hybrids have not been studied yet. Therefore, this study was directed to detect the gene expression of digestive enzymes and nutrient transporters in the yolk sac membrane and small intestine of the embryos in layer hybrid and pure breeds. A total of 354 hatching eggs were collected from 29 wk old Denizli, Gerze and Lohman White (LW) breeder flocks. Twelve eggs from each genotype were selected at embryonic day 19 (E19) and day 21 (E21). APN, SI, PepT1, EAAT3, CAT1, B0AT, SGLT1 and GLUT5 mRNA expressions were evaluated in the yolk sac membrane (YSM) and small intestine of the embryos from different genotypes. Expressions of APN and EAAT3 in the small intestine of Denizli embryo were upregulated from E19 to E21. B0AT, PepT1 and SGLT1 expressions were upregulated in the small intestine of pure breed and layer hybrid embryos with increasing embryonic age. SI expression in the small intestine of the LW embryos was upregulated from E19 to E21. APN, B0AT and EAAT3 expressions in the YSM of Denizli embryos were dowregulated from E19 to E21. EAAT3 and SGLT1 expressions in the YSM of Gerze embryos were upregulated at E21 and compared to E19. Taken together, our results indicate that genotype and embryonic age influenced the expression of digestive enzymes and nutrient transporter genes in the small intestine and YSM of embryos.

Induced PTF1a expression in pancreatic ductal adenocarcinoma cells activates acinar gene networks, reduces tumorigenic properties, and sensitizes cells to gemcitabine treatment.

Pancreatic acinar cells synthesize, package, and secrete digestive enzymes into the duodenum to aid in nutrient absorption and meet metabolic demands. When exposed to cellular stresses and insults, acinar cells undergo a dedifferentiation process termed acinar–ductal metaplasia (ADM). ADM lesions with oncogenic mutations eventually give rise to pancreatic ductal adenocarcinoma (PDAC). In healthy pancreata, the basic helix‐loop‐helix (bHLH) factors MIST1 and PTF1a coordinate an acinar‐specific transcription network that maintains the highly developed differentiation status of the cells, protecting the pancreas from undergoing a transformative process. However, when MIST1 and PTF1a gene expression is silenced, cells are more prone to progress to PDAC. In this study, we tested whether induced MIST1 or PTF1a expression in PDAC cells could (i) re‐establish the transcriptional program of differentiated acinar cells and (ii) simultaneously reduce tumor cell properties. As predicted, PTF1a induced gene expression of digestive enzymes and acinar‐specific transcription factors, while MIST1 induced gene expression of vesicle trafficking molecules as well as activation of unfolded protein response components, all of which are essential to handle the high protein production load that is characteristic of acinar cells. Importantly, induction of PTF1a in PDAC also influenced cancer‐associated properties, leading to a decrease in cell proliferation, cancer stem cell numbers, and repression of key ATP‐binding cassette efflux transporters resulting in heightened sensitivity to gemcitabine. Thus, activation of pancreatic bHLH transcription factors rescues the acinar gene program and decreases tumorigenic properties in pancreatic cancer cells, offering unique opportunities to develop novel therapeutic intervention strategies for this deadly disease.

Influence of low protein diets on gene expression of digestive enzymes and hormone secretion in the gastrointestinal tract of young weaned piglets

To investigate dietary protein level effects on digestive mechanisms, weaned piglets were fed for 45 d with diets containing 20%, 17%, or 14% crude protein (CP) supplemented to meet requirements for essential amino acids. This article describes the influence of dietary protein on gastrointestinal hormones and expression of an array of digestive enzymes in the gastrointestinal tract and pancreas. Results indicated that there were no significant differences in expression of enzymes involved in carbohydrate digestion, except for maltase in the duodenum. In the jejunum, amylase expression in pigs fed 20% CP was much higher than that in pigs fed other diets (P<0.05) and maltase expression in those fed 17% CP was higher than that in other treatments (P<0.05). Although there were no remarkable differences in expression of aminopeptidase in the small intestine or carboxypeptidase in the pancreas (P>0.05), there was a trend towards higher expression of various proteases in pigs fed 17% CP. The duodenal expression of enteropeptidase in diets with 14% and 17% CP was significantly higher than that with 20% CP (P<0.05), but treatment differences did not existed in jejunum (P>0.05). The expression of GPR93 as a nutrient-responsive G protein-coupled receptor in 14% and 17% CP diets was significantly higher than that in 20% CP diet in the small intestine (P<0.05). The expressions of genes for pancreatic enzymes, lipase and elastase, were significantly higher in pigs fed diets with low CP, while similar trends occurred for carboxypeptidase, chymotrypsin and amylase. Conversely, the gastric expressions of pepsinogen A and progastricsin were lower with the 17% CP diet. Differences between treatments were found in the gastric antral contents of cholecystokinin and somatostatin: both increased in pigs fed 17% CP, accompanied by decreased content of motilin, which was also seen in plasma concentrations. These patterns were not reflected in duodenal contents. In general, 17% dietary CP was beneficial to the digestion of nutrient substance in the gastrointestinal tract.

Dietary lipid requirements of larval genetically improved farmed tilapia,Oreochromis niloticus(L.), and effects on growth performance, expression of digestive enzyme genes, and immune response

The present study was performed to investigate the effects of dietary lipid level on growth performance, antioxidant defense, and mRNA levels of digestive enzymes and immune genes in larval genetically improved farmed tilapia (Oreochromis niloticus). The results show that larvae fed lipid levels of 4–11.5% had greater weight gain (WG), feed efficiency, protein efficiency ratio and survival than larvae fed the other dietary lipid levels (P < 0.05). No difference whole-body crude protein, ash or moisture contents were found between treatments (P > 0.05) but lipid contents increased as dietary lipid level was increased. The 8% and 11.5% dietary lipid levels had stimulatory effects on trypsin mRNA level compared with those of larvae fed the 15% and 18.5% lipid diets. Intestinal and liver amylase mRNA levels decreased in larvae fed the 18.5% lipid diet, following the decrease in dietary starch. Analysis of the secondary curve equation for WG indicated that the optimal dietary lipid level in larval tilapia was 8.56%. In addition, the 4–11.5% lipid levels improved superoxide dismutase and glutathione peroxidase activities and increased mRNA levels of heat shock protein70, hepcidin antimicrobial peptide-1, and C-type lysozyme in the liver of larvae (P < 0.05). A 192-h Streptococcus iniae challenge study was conducted after the 35-day feeding trial, and the results showed that post-challenge mortality of larvae fed the 11.5% lipid level was the lowest and enhanced the immune activities.

Prawn Shell Chitosan Has Anti-Obesogenic Properties, Influencing Both Nutrient Digestibility and Microbial Populations in a Pig Model.

The potential of natural products to prevent obesity have been investigated, with evidence to suggest that chitosan has anti-obesity effects. The current experiment investigated the anti-obesity potential of prawn shell derived chitosan on a range of variables relevant to obesity in a pig model. The two dietary treatment groups included in this 63 day study were: T1) basal diet and T2) basal diet plus 1000 ppm chitosan (n = 20 gilts per group (70 ± 0.90 kg). The parameter categories which were assessed included: performance, nutrient digestibility, serum leptin concentrations, nutrient transporter and digestive enzyme gene expression and gut microbial populations. Pigs offered chitosan had reduced feed intake and final body weight (P< 0.001), lower ileal digestibility of dry matter (DM), gross energy (GE) (P< 0.05) and reduced coefficient of apparent total tract digestibility (CATTD) of gross energy and nitrogen (P<0.05) when compared to the basal group. Fatty acid binding protein 2 (FABP2) gene expression was down-regulated in pigs offered chitosan (P = 0.05) relative to the basal diet. Serum leptin concentrations increased (P< 0.05) in animals offered the chitosan diet compared to pigs offered the basal diet. Fatness traits, back-fat depth (mm), fat content (kg), were significantly reduced while lean meat (%) was increased (P<0.05) in chitosan supplemented pigs. Pigs offered chitosan had decreased numbers of Firmicutes in the colon (P <0.05), and Lactobacillus spp. in both the caecum (P <0.05) and colon (P <0.001). Bifidobacteria populations were increased in the caecum of animals offered the chitosan diet (P <0.05). In conclusion, these findings suggest that prawn shell chitosan has potent anti-obesity/body weight control effects which are mediated through multiple biological systems in vivo.

Low-protein diets affect ileal amino acid digestibility and gene expression of digestive enzymes in growing and finishing pigs.

The objective of this study was to evaluate effects of dietary crude protein (CP) intake on ileal amino acid digestibilities and expression of genes for digestive enzymes in growing and finishing pigs. In Experiment 1, 18 growing pigs (average initial BW = 36.5 kg) were assigned randomly into one of three treatments (n = 6/treatment group) representing normal (18 % CP), low (15 % CP), and very low (12 % CP) protein intake. In Experiment 2, 18 finishing pigs (average initial BW = 62.3 kg) were allotted randomly into one of three treatments (n = 6/treatment group), representing normal (16 % CP), low (13 % CP) and very low (10 % CP) protein intake. In both experiments, diets with low and very low CP were supplemented with crystalline amino acids to achieve equal content of standardized ileal digestible Lys, Met, Thr, and Trp, and were provided to pigs ad libitum. Daily feed intake, BW, and feed/gain ratios were determined. At the end of each experiment, all pigs were slaughtered to collect pancreas, small-intestine samples, and terminal ileal chymes. Samples were used for determining expression of genes for digestive enzymes and ileal amino acid digestibilities. Growing pigs fed the 12 % CP and 15 % CP diets had lower final body weight (P < 0.01) and ADG (P < 0.0001) when compared with pigs fed the 18 % dietary CP diet. Growing pigs fed with the 12 % CP diet showed higher digestibilities for CP (P < 0.05), DM (P < 0.05), Lys (P < 0.0001), Met (P < 0.01), Cys (P < 0.01), Thr (P < 0.01), Trp (P < 0.05), Val (P < 0.05), Phe (P < 0.05), Ala (P < 0.05), Cys (P < 0.01), and Gly (P < 0.05) than those fed the 18 % CP diet. Finishing pigs fed the 16 % CP diet had a higher (P < 0.01) final body weight than those fed the 10 % CP diet. mRNA levels for digestive enzymes (trypsinogen, chymotrypsin B, and dipeptidases-II and III) differed among the three groups of pigs (P < 0.05), and no difference was noted in the genes expression between control group and lower CP group. These results indicated that a reduction of dietary CP by a six-percentage value limited the growth performance of growing-finishing pigs and that a low-protein diet supplemented with deficient amino acids could reduce the excretion of nitrogen into the environment without affecting weight gain.