Can intestinal absorption of dietary protein be improved through early exposure to plant-based diet?

Effects of Oregano (Origanum vulgare) Essential Oil Supplementation on Growth Performance of Zebrafish (Danio rerio) Fed a High-Inclusion Soybean Meal Diet

Soybean meal (SBM) has become a common dietary replacement for fish meal (FM) in aquafeed. However, at high inclusions, SBM has been shown to have negative impacts presenting as reduced feed intake and intestinal inflammation. Medicinal plant extracts, namely essential oils, have been used to promote growth performance and immune response. The objective of this study was to investigate the potential therapeutic effects of oregano (Origanum vulgare) essential oil (OEO) inclusion on utilization of a high-inclusion SBM diet using zebrafish as a model. Five diets were used in this study: reference-FM-based diet, control-55.7% inclusion SBM diet, and three experimental SBM-based diets OEO1, OEO2, and OEO3 that were supplemented with 1%, 2%, or 3% of oregano oil, respectively. The FM group had overall better growth performance when compared with the other treatment groups; however, the OEO3 mean weight and feed conversion ratio were not significantly different from the FM group (p > 0.05) and were significantly improved compared with the SBM group (p < 0.05). Similarly, OEO2 total length was not significantly different from FM (p > 0.05) but significantly higher than the SBM group (p < 0.05). Expression of inflammation-related genes did not significantly differ between the OEO groups and the SBM-only group. However, the OEO2 and OEO3 groups displayed improved growth performance compared with the SBM group, suggesting that inclusion of OEO at or above 2% inclusion may help to alleviate common symptoms induced by a high-inclusion SBM diet.

Chronic social isolation affects feeding behavior of juvenile zebrafish (Danio rerio)

Many organisms exhibit social behaviors and are part of some scheme of social structure. Zebrafish are highly social, shoaling fish and therefore, social isolation may have notable impacts on their physiology and behavior. The objective of this study was to evaluate the effects of social isolation on feed intake, monoaminergic system related gene expression, and intestinal health of juvenile zebrafish fed a high-inclusion soybean meal based diet. At 20 days post-fertilization zebrafish were randomly assigned to chronic isolation (1 fish per 1.5 L tank) or social housing (6 fish per 9 L tank) with 18 tanks per treatment group (n = 18). Dividers were placed between all tanks to prevent visual cues between fish. Zebrafish were fed a commercial fishmeal based diet until 35 days post-fertilization and then fed the experimental high-inclusion soybean meal based diet until 50 days post-fertilization. At the end of the experiment (51 days post-fertilization), the mean total length, weight, and weight gain were not significantly different between treatment groups. Feed intake and feed conversion ratio were significantly higher in chronic isolation fish than in social housing fish. Expression of monoaminergic and appetite-related genes were not significantly different between groups. The chronic isolation group showed higher expression of the inflammatory gene il-1b, however, average intestinal villi width was significantly smaller and average length-to-width ratio was significantly higher in chronic isolation fish, suggesting morphological signs of inflammation were not present at the time of sampling. These results indicate that chronic isolation positively affects feed intake of juvenile zebrafish and suggest that isolation may be useful in promoting feed intake of less-palatable diets such as those based on soybean meal.

Dietary aflatoxins exposure, environmental enteropathy, and their relation with childhood stunting

Childhood stunting is a global phenomenon affecting more than 149 million children under the age of 5 worldwide. Exposure to aflatoxins (AFs) in utero, during breastfeeding, and consumption of contaminated food affect the gut microbiome, resulting in intestinal dysfunction and potentially contributing to stunting. This review explores the potential relationship between AF exposure, environmental enteropathy and childhood stunting. AFs bind to DNA, disrupt protein synthesis and elicit environmental enteropathy (EE). An EE alters the structure of intestinal epithelial cells, impairs nutrient uptake and leads to malabsorption. This article proposes possible intervention strategies for researchers and policymakers to reduce AF exposure, EE and childhood stunting, such as exposure reduction, the implementation of good agricultural practices, dietary diversification and improving environmental water sanitation and hygiene.

Zebrafish Feed Intake: A Systematic Review for Standardizing Feeding Management in Laboratory Conditions

Zebrafish are one of the most used animal models in biological research and a cost-effective alternative to rodents. Despite this, nutritional requirements and standardized feeding protocols have not yet been established for this species. This is important to avoid nutritional effects on experimental outcomes, and especially when zebrafish models are used in preclinical studies, as many diseases have nutritional confounding factors. A key aspect of zebrafish nutrition is related to feed intake, the amount of feed ingested by each fish daily. With the goal of standardizing feeding protocols among the zebrafish community, this paper systematically reviews the available data from 73 studies on zebrafish feed intake, feeding regimes (levels), and diet composition. Great variability was observed regarding diet composition, especially regarding crude protein (mean 44.98 ± 9.87%) and lipid content (9.91 ± 5.40%). Interestingly, the gross energy levels of the zebrafish diets were similar across the reviewed studies (20.39 ± 2.10 kilojoules/g of feed). In most of the reviewed papers, fish received a predetermined quantity of feed (feed supplied). The authors fed the fish according to the voluntary intake and then calculated feed intake (FI) in only 17 papers. From a quantitative point of view, FI was higher than when a fixed quantity (pre-defined) of feed was supplied. Also, the literature showed that many biotic and abiotic factors may affect zebrafish FI. Finally, based on the FI data gathered from the literature, a new feeding protocol is proposed. In summary, a daily feeding rate of 9-10% of body weight is proposed for larvae, whereas these values are equal to 6-8% for juveniles and 5% for adults when a dry feed with a proper protein and energy content is used.

Cottonseed Meal Protein Hydrolysate Improves the Growth Performance of Chinese Mitten Crab (Eriocheir sinensis) by Promoting the Muscle Growth and Molting Performance

Growth retardation and prolonged marketing cycle have been noticed in the practical aquaculture of Chinese mitten crab (Eriocheir sinensis) fed with artificial feed. Plant protein hydrolysates contain a large number of small peptides and free amino acids, which can improve the growth performance of aquatic animals. However, the potential mechanisms are still not well elucidated. In this research, the influences of cottonseed meal protein hydrolysate (CPH) on the growth, feed utilization, muscle growth, and molting performance were investigated in E. sinensis. A total of 240 crabs (mean body weight 37.32 ± 0.38 g) were individually randomly distributed to six diets supplemented with 0%, 0.2%, 0.4%, 0.8%, 1.6%, and 3.2% of CPH for 12 weeks. These findings indicated that the addition of CPH at 0.4% significantly increased the survival rate, body protein gain, apparent protein utilization, trypsin and pepsin activities, and the methyl farnesoate content. When the dose reached 0.8%, the weight growth ratio, meat yield, ecdysone concentration, and the transcription of the ecdysteroid receptor all significantly increased, while the transcriptions of both myostatin and molt-inhibiting hormone significantly decreased. When CPH was added at 1.6%-3.2%, the feed conversion ratio, body crude protein content, Na+/K+-ATPase activity, and the molting ratio were all significantly improved, while the opposite was true for the transcription of the transforming growth factor-β type I receptor. The investigation results indicated that when added above 0.4%, CPH could stimulate the growth performance of E. sinensis and promote the muscle growth and molting performance.

Pineapple waste in animal feed: A review of nutritional potential, impact and prospects

Pineapple is a commodity and economic fruit with a high market potential worldwide. Almost 60 % of the fresh pineapple, such as peels, pulp, crowns and leaves, are agricultural waste. It is noteworthy that the waste has a high concentration of crude fibre, proteins, ascorbic acid, sugars and moisture content. The pineapple waste utilisation in animal feed has recently drawn the attention of many investigators to enhance growth performance and concomitantly reduce environmental pollution. Its inclusion in animal feed varies according to the livestock, such as feed block, pelleted or directly used as a roughage source for ruminants. The pineapple waste is also fermented to enrich the nutrient content of poultry feed. To date, the inclusion of pineapple waste in animal feed is optimistic only not for livestock but also for farmed fish. Indeed, it is an ideal strategy to improve the feed supply to the farm. This paper aims to overview the source, nutritional composition, and application of pineapple waste in animal feed. The recent findings on its effect on animal growth performance, nutrition and disease control are discussed comprehensively and summarised. The review also covers its benefits, potential impacts on sustainable farming and future perspectives.

Molecular programming of the hepatic lipid metabolism via a parental high carbohydrate and low protein diet in rainbow trout

It is now recognised that parental diets could alter their offspring metabolism, concept known as nutritional programming. For agronomic purposes, it has been previously proposed that programming could be employed as a strategy to prepare individual for future nutritional challenges. Concerning cultured fish that belong to high trophic level, plant-derived carbohydrates are a possible substitute for the traditional protein-rich fishmeal in broodstock diet, lowering thus the dietary protein-to-carbohydrate ratio (HC/LP nutrition). However, in mammals, numerous studies have previously demonstrated that parental HC/LP nutrition negatively affects their offspring in the long term. Therefore, the question of possible adaptation to plant-based diets, via parental nutrition, should be explored. First, the maternal HC/LP nutrition induced a global DNA hypomethylation in the liver of their offspring. Interestingly at the gene expression level, the effects brought by the maternal and paternal HC/LP nutrition cumulated in the liver, as indicated by the altered transcriptome. The paternal HC/LP nutrition significantly enhanced cholesterol synthesis at the transcriptomic level. Furthermore, hepatic genes involved in long-chain polyunsaturated fatty acids were significantly increased by the parental HC/LP nutrition, affecting thus both hepatic and muscle fatty acid profiles. Overall, the present study demonstrated that lipid metabolism could be modulated via a parental nutrition in rainbow trout, and that such modulations have consequences on their progeny phenotypes.

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

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

Effects of applying nutritional programming at different early stages of Largemouth bass (Micropterus salmoides, Lacepède) development on growth and dietary plant protein utilization

Plant protein (PP) utilization in fish is limited due to lower digestibility compared to fishmeal (FM) and the presence of antinutritional factors. Its utilization can be improved by nutritional programming (NP), a method wherein a fish is provided a nutritional stimulus early in life which can alter their physiology. NP has been shown to be effective but methods of applying NP are varied and have been applied at different stages of development with different outcomes. To find the optimal timeframe to perform NP in fish early stages Largemouth bass (Micropterus salmoides, Lacepède) were nutritionally programmed at three different ages in early development. In this study bass were programmed with: (1) live food enriched with soybean meal (SBM) from 6 to 15 days post-hatch (dph) (NPL), (2) SBM-based formulated diet from 16 to 25 dph (NPD1) and (3) formulated SBM-diet from 26 to 35 dph (NPD2). After programming, each group was fed FM-diet before being refed SBM-diet from 100 to 172 dph. A positive control (PC) was fed FM-diet throughout. Final average body weight of PC was significantly higher than NPD1 and NPD2 but did not significantly differ from NPL. Overall NPL showed much improved growth and utilization of PP compared to NPD1 and was similar to growth achieved by PC. This study showed an optimum window of time exists wherein NP of Largemouth bass yields the best impact on growth in the larval stage and later in life when fed SBM-diet. Programming should be performed right after mouth opening using enriched live food and can result in growth similar to non-programmed fish fed FM-based diet. Programming effects similar to that of the live food approach can be achieved with formulated diet, however it is crucial that Largemouth bass are of a proper age and sufficiently developed when programmed with dry food or severe impacts on growth can occur.

Does Exposure of Broodstock to Dietary Soybean Meal Affect Its Utilization in the Offspring of Zebrafish (Danio rerio)?

Simple Summary

Replacement of fishmeal in fish diets with plant protein has been an ongoing challenge. High-quality plant protein concentrates are widely used since their digestibility can be comparable to fishmeal. However, their price can exceed the cost of marine raw materials. Progress with utilization of lower-quality plant protein sources has been made but a number of concerns must be overcome to maintain acceptable growth rates at high fishmeal substitution levels. Nutritional programming represents a promising approach to offset the negative effects of dietary plant protein through its exposure in early life. We tested an unconventional programming strategy by exposing parental zebrafish to soybean meal diet to improve dietary soybean meal utilization in progeny fish. The study observed a strong trend showing better growth performance between progeny zebrafish fed soybean meal diet that originated from broodstock exposed to soybean meal as opposed to progeny fish fed soybean meal diet that originated from fishmeal diet fed broodstock. However, the study found no changes in the richness, diversity, or composition of gut microbial communities associated with progeny fish from fishmeal or soybean meal fed broodstock. Hence, the mechanism behind nutritional programming does not seem to be associated with modified gut microbiome.

Abstract

Nutritional programming (NP) is a concept in which early nutritional events alter the physiology of an animal and its response to different dietary regimes later in life. The objective of this study was to determine if NP via broodstock with dietary plant protein (PP) has any effect on the gut microbiome of the progeny fish and whether this modified gut microbiome leads to better utilization of PP diet. The experiment consisted of four different treatments as follows: (1) progeny that received FM diet obtained from fishmeal (FM)-fed broodstock (FMBS-FM, +control); (2) progeny that received PP diet obtained from FM-fed parents (FMBS-PP); (3) progeny that received PP diet obtained from “nutritionally programmed” parents (PPBS-PP; −control); and (4) progeny that received FM diet obtained from “nutritionally programmed” parents (PPBS-FM). Zebrafish was used as a model species. This study found that parental programming seems to have some positive effect on dietary PP utilization in progeny. However, the influence of NP with PP through broodstock on gut microbiota of the offspring fish was not detected.

Feeding Rate and Protein Quality Differentially Affect Growth and Feeding Efficiency Response Variables of Zebrafish (Danio rerio)

Manipulating feeding rate and protein quality may improve growth and feeding efficiency of cultured species. However, whether feeding rate, protein quality, or their interaction has a greater effect on growth and feeding efficiency response variables is unknown. To determine whether feeding rate and protein quality individually or interactively affect growth and feeding efficiency, juvenile Zebrafish (Danio rerio) were either offered nutritionally similar diet consisting of either menhaden fishmeal protein or a 100% replacement of fishmeal with soybean meal-based protein restrictively or to satiation. Total length, weight, feed intake, and feed conversion ratio (FCR) were measured throughout the duration of the study. Protein quality and feeding rate individually and interactively affected feed intake and FCR: Zebrafish offered feed to satiation had higher growth and FCR than those fed restrictively, and Zebrafish fed soybean meal-based diet showed lower growth and higher FCR and feed intake compared to those fed fishmeal-based diet, although magnitude of response depended on feeding rate. These findings likely indicate lower digestibility of soybean meal or the presence of antinutritional factors in soybean meal that led to impaired nutrient absorption of fish offered soybean meal-based diet. Differences in measured response variables between protein qualities and feeding rates highlight the importance of determining interactive effects in nutritional studies.

Co-interventions with Clostridium butyricum and soluble dietary fiber targeting the gut microbiota improve MAFLD via the Acly/Nrf2/NF-κB signaling pathway

Purpose: The pathogenesis of metabolic associated fatty liver disease (MAFLD) is complex. Lipid metabolic disorder, chronic inflammation, and oxidative stress are the core events for MAFLD. Dietary intervention is an important treatment strategy for preventing the onset and progression of MAFLD. Clostridium butyricum (CB) and soluble dietary fiber (SDF) are often considered beneficial for health. We explored how two microbiota-targeted interventions (SDF and CB) influence the hepatic immune system, oxidative stress, and lipid metabolism in MAFLD mice. Methods: To explore the role of SDF and CB in MAFLD, we generated MAFLD mouse models by feeding C57BL/6 mice with a high-fat diet (HFD). After 8 weeks of intervention, we measured immune cell function, lipid metabolism, and oxidative stress levels in the livers of mice. Results: Single intervention with SDF or CB was not effective in improving MAFLD; however, co-interventions with SDF and CB increased microbiota diversity and decreased inflammation, oxidative stress, and lipid synthesis. Moreover, we determined that co-intervention with SDF and CB mediated fatty acid oxidation by activating the Acly/Nrf2/NF-κB signaling pathway. Most importantly, co-intervention exerted anti-inflammatory effects by inhibiting the differentiation of macrophages into pro-inflammatory M1 macrophages. Conclusion: This study show that co-intervention with SDF and CB can improve MAFLD, and co-intervention with  SDF and CB are suggested to be potential gut microbiota modulators and therapeutic substances for MAFLD.

The use of dipeptide supplementation as a means of mitigating the negative effects of dietary soybean meal on Zebrafish Danio rerio

Soybean meal (SBM) inclusion in aquaculture diets has been found to negatively affect growth and induce intestinal inflammation in fish. The objective of this study was to determine the effect of health-promoting dipeptide supplementation into SBM-based feeds on growth performance, intestinal health, and muscle free amino acid composition, an indicator of dietary amino acid availability, in a zebrafish model. There were five treatment groups in this study. The first group ((+) Control) received a fishmeal-based diet. The second group ((-) Control) received SBM-based diet. The last three groups (Ala-Glu, Car, and Ans) were fed SBM-based diets, supplemented with alanyl-glutamine, carnosine, and anserine respectively. The Ala-Glu and Car groups experienced a significantly higher weight gain than the (-) Control group, weighing 35.38% and 33.96% more, respectively at the conclusion of the study. There were no significant differences in gene expression among the groups, but Ala-Glu had the highest expression of both nutrient absorption genes measured, PepT1 and fabp2. Ala-Glu had significantly longer intestinal villi, and a significantly higher villus length-to-width ratio than the (-) Control group. The Car group had a significantly higher post-prandial tissue concentration of lysine, compared to the (-) Control group. The increase in villus surface area and expression of nutrient absorption genes represent an improvement in intestinal absorptive capacity in the Ala-Glu group. The results from this study provide support for the use of alanyl-glutamine and carnosine supplementation as a means of improving growth performance of zebrafish fed with a high level SBM-based diet.

The use of live food as a vehicle of soybean meal for nutritional programming of largemouth bass Micropterus salmoides

Nutritional Programming (NP) has been studied as a means of improving dietary plant protein (PP) utilization in different fish species. This study investigated the use of enriched live feed as a vehicle for NP in larval fish. The objective of this study was to determine the effect of NP induced during the larval stage via PP-enriched live feed on: (1) growth performance; (2) expression of genes associated with inflammation and any morphological changes in the intestine; and (3) muscle free amino acid composition in largemouth bass (Micropterus salmoides) during its later life stages. Two diets were used in this study, a fish meal (FM)-based diet, and a soybean mean (SBM)-based diet, serving as the PP diet. There were 4 groups in this study. The two control groups, ( +) Control and (-) Control, were not programmed and received the FM-diet and SBM-diet, respectively throughout the whole trial after the live feed stage (27-122 days post hatch (dph). The next group, programmed, was programmed with SBM-enriched Artemia nauplii during the live feed stage (4-26 dph) and challenged with the SBM-diet during the final stage of the study (79-122 dph). The final group, non-programmed, did not receive any programming and, was challenged with the SBM-diet during the final stage of the study. The programmed group experienced a significantly higher (%) weight gain during the PP-Challenge than the non-programmed group. In addition, the live feed programming resulted in significantly longer distal villi, and a higher villi length to width ratio, compared to the non-programmed group. No significant effects on free amino acid composition and gene expression were observed between the programmed and non-programmed group, except for an increased post-prandial concentration of free proline in the programmed group. The results of this study support use of live feed as a vehicle for nutritional programming and improving the growth performance of largemouth bass fed with a SBM-based diet.

Nutritional Programming with Dietary Soybean Meal and Its Effect on Gut Microbiota in Zebrafish (Danio rerio)

Nutritional programming (NP) is considered a promising approach that can counteract the negative effects of dietary plant protein (PP) by introducing PP to fish in the early developmental stages. Therefore the objective of our study was to assess the effect of NP on PP utilization and the gut microbiome in zebrafish Danio rerio. The study included four treatment groups: (1) a positive control group that received a fishmeal (FM) diet throughout the entire trial (+ control); (2) a negative control group that received PP diet throughout the entire trial (- control); (3) an NP group that received dietary PP during the larval stage followed by FM-based diet during the juvenile stage and PP diet again during a PP challenge in the grow-out phase (NP-PP); and (4) an FM-group that received FM-based diet during the larval and juvenile stages and was challenged with a PP diet during the grow-out phase (NP-FM). During the PP challenge, the NP-PP group achieved the highest weight gain compared to the (-) control and NP-FM groups. The relative abundance of certain phyla such as Chloroflexi, Planctomycetes, and Bacteroidetes presented higher values in some groups at early juvenile stage. The fish gut microbiome also presented differences throughout the study.