Both teeth and the digestive tract show adaptations that are commonly interpreted in the context of trophic guilds—faunivory, herbivory and omnivory. Teeth prepare food for the digestive tract, and ...dental evolution focuses on increasing durability and functionality; in particular, size reduction of plant particles is an important preparation for microbial fermentative digestion. In narratives of digestive adaptations, microbes are typically considered as service providers, facilitating digestion. That the majority of ‘herbivorous’ (and possibly ‘omnivorous’) mammals display adaptations to maximize microbes' use as prey—by harvesting the microbes multiplying in their guts—is less emphasized and not reflected in trophic labels. Harvesting of microbes occurs either via coprophagy after separation from indigestible material by a separation mechanism in the hindgut, or from a forestomach by a ‘washing mechanism’ that selectively removes fines, including microbes, to the lower digestive tract. The evolution of this washing mechanism as part of the microbe farming niche opened the opportunity for the evolution of another mechanism that links teeth and guts in an innovative way—the sorting and cleaning of not-yet-sufficiently-size-reduced food that is then re-submitted to repeated mastication (rumination), leading to unprecedented chewing and digestive efficiency.
This article is part of the theme issue ‘Food processing and nutritional assimilation in animals’.
A method to characterise rheological and microstructure features of whole digesta collected from pigs fed meat-containing western style diets is described. Digesta are shown to contain suspensions of ...meat fibre particles up to 300 μm in size which exhibit weak gel behaviour, have a dynamic viscosity higher than steady shear viscosity indicative of structural breakdown at the initiation of flow, and shear thinning behaviour under steady shear. The power law index approach is useful for capturing the overall features of rheological behaviour under both small (n*<0.3) and large deformation (typically 0.2 < n < 0.5) conditions. Values obtained for rheological parameters represent a balance between the digestion of structural components (meat particles and starch granules in this case) with the absorption of water along the small intestine, and result in the absence of any systematic pattern as a function of small intestinal site. Both primary rheological data (G′, G″, η, η*) and power law index parameters show a high level of variability between animals fed identical diets. This study provides a baseline from which to investigate the in vivo effects of hydrocolloids on the rheology of porcine digesta from diets representative of human meals.
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•Methodology for porcine small intestinal digesta characterisation developed.•Systematic changes observed in digesta microstructure during small intestinal transit.•Rheological properties reflect balance between digesta hydrolysis & net water uptake.•Large variations in modulus & viscosity values for genetically-similar animals fed same diet.
The reticulorumen (RR) fractional passage rate (kp; /h) of particles and solutes plays an important role in fiber digestion, methane production, and microbial yield. However, none of the available ...models for predicting RR kp consider individuals' characteristics of growing goats. The objective was to develop empirical models for predicting the RR kp of particles and solutes in growing goats. Our database involved 175 individual records of castrated males (n = 61), females (n = 57), and intact males (n = 57) growing Saanen goats fed ad libitum, 75% or 50% of ad libitum. Goats were slaughtered around 15, 22, 30, 37, or 45 kg BW. We used Akaike’s information criterion to select the best prediction models. We evaluated the predictive ability of these models using Lin’s concordance correlation coefficient (CCC) and RMSE of prediction (RMSPE) in a 4-fold cross-evaluation. The DM intake (DMI; kg/day), potentially digestible NDF intake (pdNDFI) level (g/kg BW), and RR wet pool size (kg) demonstrated similar importance in predicting RR kp of solutes (CCC = 0.59; RMSPE = 0.050 /h or 34.43%). However, when RR wet pool size was not included in the model, RR kp of solutes could still be precisely and accurately predicted using only DMI level (g/kg BW) (CCC = 0.47; RMSPE = 0.053 /h or 36.58%). The RR wet tissues and wet pool size (kg), NDF intake (NDFI) (kg/day), and indigestible NDFI (iNDFI):NDFI ratio were important predictors of RR kp of particles (CCC = 0.51; RMSPE = 0.0064 /h or 25.43 %). However, when RR wet tissues and wet pool size were not included in the model, iNDFI:NDFI ratio, NDFI level (g/kg BW), and RR kp of solutes presented greater importance in predicting RR kp of particles (CCC = 0.20; RMSPE = 0.0074 /h or 29.55%). Sex was not a significant predictor variable for the selected models. In summary, the RR kp of solutes was more dependent on feed intake level while the RR kp of particles was more dependent on diet composition and RR kp of solutes. Our models were precise and accurate for predicting RR kp of solutes (CCC = 0.57 and 0.47; RMSPE = 0.051 and 0.054 /h) and particles (CCC = 0.48 and 0.17; RMSPE = 0.0066 and 0.0076 /h) after cross-evaluation. This suggests that our models can be integrated into feeding systems with mechanistic approaches that simulate other reticulorumen functions, such as digestion, microbial growth, and methane emission.
This study compared two collection methods (CMs) to obtain ileal content from broiler chickens to determine apparent ileal amino acid digestibility coefficients (AIAAD). CM1 consisted of collecting ...the digesta by gently squeezing the ileum, while in CM2, the ileal digesta was flushed with distilled water. A total of 130 one-day-old male chicks were randomly distributed among 10 cages, using five replicate cages per CM. Birds were fed ad libitum with a standard starter diet from 0 to 18 d of age. At 18d, the diet switched to a corn-based semi-purified diet with 0.5% titanium dioxide (TiO2) as the indigestible marker. At 21d, birds were euthanized, and ileal digesta was collected using one of the two CMs. Bird performance was monitored; feed and lyophilized ileum content samples were analyzed to determine amino acids (AAs) and Ti content to determine AIAAD. A two-sided T-test and an F-test two-sided were performed to determine differences among the CMs’ means and variances, respectively. All significant differences were considered at a P-value < 0.05. Bird performance was similar for both groups throughout the experiment (P > 0.05). No significant differences between CMs were observed in the AIAAD coefficients for any of the amino acids analyzed (P < 0.05). The variances were significantly different for 6 AA (Iso, Lys, Thr, Ala, Asp, Glu; P < 0.05). In addition, four AAs approach significance (Leu, Met, Val, Pro; P < 0.1). The numeric values of the AAs variances were consistently higher when the sample was obtained using CM1. Squeezing may increase variability by enhancing endogenous losses like sloughed cells and mucin, underestimating digestibility in some samples. Using CM2 (flushing with distilled water) would provide more consistent and uniform results. This approach not only diminishes the likelihood of errors but also contributes to the standardization of methodologies applied in digestibility trials within the poultry research field.
To better understand salmon GI tract microbial community dynamics in relation to diet, a feeding trial was performed utilising diets with different proportions of fish meal, protein, lipid and energy ...levels. Salmon gut dysfunction has been associated with the occurrence of casts, or an empty hind gut. A categorical scoring system describing expressed digesta consistency was evaluated in relation to GI tract community structure. Faster growing fish generally had lower faecal scores while the diet cohorts showed minor differences in faecal score though the overall lowest scores were observed with a low protein, low energy diet. The GI tract bacterial communities were highly dynamic over time with the low protein, low energy diet associated with the most divergent community structure. This included transiently increased abundance of anaerobic (Bacteroidia and Clostridia) during January and February, and facultatively anaerobic (lactic acid bacteria) taxa from February onwards. The digesta had enriched populations of these groups in relation to faecal cast samples. The majority of samples (60–86 %) across all diet cohorts were eventually dominated by the genus Aliivibrio. The results suggest that an interaction between time of sampling and diet is most strongly related to community structure. Digesta categorization revealed microbes involved with metabolism of diet components change progressively over time and could be a useful system to assess feeding responses.
As food transits the gastrointestinal tract, food structures are disrupted and nutrients are absorbed across the gut barrier. In the past decade, great efforts have focused on the creation of a ...consensus gastrointestinal digestion protocol (i.e., INFOGEST method) to mimic digestion in the upper gut. However, to better determine the fate of food components, it is also critical to mimic food absorption in vitro. This is usually performed by treating polarized epithelial cells (i.e., differentiated Caco-2 monolayers) with food digesta. This food digesta contains digestive enzymes and bile salts, and if following the INFOGEST protocol, at concentrations that although physiologically relevant are harmful to cells. The lack of a harmonized protocol on how to prepare the food digesta samples for downstream Caco-2 studies creates challenges in comparing inter laboratory results. This article aims to critically review the current detoxification practices, highlight potential routes and their limitations, and recommend common approaches to ensure food digesta is biocompatible with Caco-2 monolayers. Our ultimate aim is to agree a harmonized consensus protocol or framework for in vitro studies focused on the absorption of food components across the intestinal barrier.
Global population is rising, leading to higher demand for meat and concerns on the environmental and economic impacts of conventional feedstuffs like corn and soybean meal. Recently there has been a ...shift towards more sustainable feedstuffs such as Spirulina (Limnospira platensis) due to its nutritional value and ability to be produced locally. Consumer awareness prompts shifts towards outdoor poultry production but presents environmental challenges due to climate change. The naked neck (Na) gene, which reduces feather coverage, and enhances growth under adverse conditions offers a possible solution for improved welfare and efficiency. This study aims to investigate the impact of a diet with 15% Spirulina inclusion on growth performance, carcass traits, and meat quality of 2 slow-growth broiler strains: naked neck (NN) and fully feathered (FF). Forty, 1-day-old male broilers, 20 per strain, were randomly assigned to either a control or a diet containing 15% Spirulina, housed individually in cages and fed ad libitum for 84 d. Growth, carcass, and meat traits were evaluated. Results indicated that animals fed a control diet generally outperformed those fed a Spirulina diet in final body weight (BW), average daily gain (ADG), feed intake (FI), and feed conversion rate (FCR) (P < 0.001). Additionally, Spirulina incorporation led to an increase in the length of the gastrointestinal tract and digesta viscosity in the duodenum plus jejunum (P < 0.05). Although there were no significant differences in breast muscle yield between dietary groups, SP-fed broilers had higher yellowness (*b) values in meat (P < 0.05). Except for the decrease in water holding capacity (WHC) observed in the NN group animals (P < 0.05), there were no significant differences between the strains for the remaining meat quality traits (P > 0.05). The 15% Spirulina inclusion increased the concentrations of n-3 polyunsaturated fatty acids (PUFA) (P < 0.0001) in breast meat and decreased (P < 0.0001) nutritional ratios. Overall, under thermoneutral conditions, animals from the NN strain showed negative effects on growth parameters. Spirulina inclusion improved certain aspects of breast meat quality, particularly fatty acid content.
The mean retention times (MRT) of solute or particles in the gastrointestinal tract and the forestomach (FS) are crucial determinants of digestive physiology in herbivores. Besides ruminants, ...camelids are the only herbivores that have evolved rumination as an obligatory physiological process consisting of repeated mastication of large food particles, which requires a particle sorting mechanism in the FS. Differences between camelids and ruminants have hardly been investigated so far. In this study we measured MRTs of solute and differently sized particles (2, 10, and 20 mm) and the ratio of large-to-small particle MRT, i.e. the selectivity factors (SF
10/2mm
, SF
20/2mm
, SF
20/10mm
), in three camelid species: alpacas (
Vicugna pacos
), llamas (
Llama glama
), and Bactrian camels (
Camelus bactrianus
). The camelid data were compared with literature data from ruminants and non-ruminant foregut fermenters (NRFF). Camelids and ruminants both had higher SF
10/2mm
FS than NRFF, suggesting convergence in the function of the FS sorting mechanism in contrast to NRFF, in which such a sorting mechanism is absent. The SF
20/10mm
FS did not differ between ruminants and camelids, indicating that there is a particle size threshold of about 1 cm in both suborders above which particle retention is not increased. Camelids did not differ from ruminants in MRT
2mm
FS, MRT
solute
FS, and the ratio MRT
2mm
FS/MRT
solute
FS, but they were more similar to ‘cattle-’ than to ‘moose-type’ ruminants. Camelids had higher SF
10/2mm
FS and higher SF
20/2mm
FS than ruminants, indicating a potentially slower particle sorting in camelids than in ruminants, with larger particles being retained longer in relation to small particles.
Phytase supplementation in broiler diets is a common practice to improve phosphorus (P) availability and to reduce P loss by excretion. An enhanced P availability, and its concomitant supplementation ...with calcium (Ca), can affect the structure of the microbial community in the digestive tract of broiler chickens. Here, we aim to distinguish the effects of mineral P, Ca, and phytase on the composition of microbial communities present in the content and the mucosa layer of the gastrointestinal tract (GIT) of broiler chickens. Significant differences were observed between digesta and mucosa samples for the GIT sections studied (
= 0.001). The analyses of 56 individual birds showed a high microbial composition variability within the replicates of the same diet. The average similarity within replicates of digesta and mucosa samples across all diets ranged from 29 to 82% in crop, 19-49% in ileum, and 17-39% in caeca. Broilers fed with a diet only supplemented with Ca had the lowest body weight gain and feed conversion values while diets supplemented with P showed the best performance results. An effect of each diet on crop mucosa samples was observed, however, similar results were not obtained from digesta samples. Microbial communities colonizing the ileum mucosa samples were affected by P supplementation. Caeca-derived samples showed the highest microbial diversity when compared to the other GIT sections and the most prominent phylotypes were related to genus
and
, known for their influence on gut health and as butyrate producers. Lower microbial diversity in crop digesta was linked to lower growth performance of birds fed with a diet only supplemented with Ca. Each diet affected microbial communities within individual sections, however, no diet showed a comprehensive effect across all GIT sections, which can primarily be attributed to the great variability among replicates. The substantial community differences between digesta and mucosa derived samples indicate that both habitats have to be considered when the influence of diet on the gut microbiota, broiler growth performance, and animal health is investigated.
► Cotyledon cell wall of navy beans imposes restrictions on gelatinization. ► Cotyledon cells restrict free access of enzymes during in vitro digestion. ► High pressure treatment increases starch ...hydrolysis in cooked beans. ► Storage of cooked beans reduces whereas re-heating increases starch hydrolysis. ► Study may help to enhance the nutritional value of carbohydrates present in beans.
Studies on the physico-chemical, microstructural characteristics and in vitro (under simulated gastric and small intestine conditions) starch digestibility of navy beans were carried out. The microstructure of raw and cooked beans observed through scanning electron microscopy (SEM) showed the presence of hexagonal or angular shaped cotyledon cells (50–100μm size) containing starch granules with a size ranging between 10 and 50μm. The extent of starch hydrolysis (%) after 120min of in vitro gastro-intestinal digestion differed between whole navy beans (∼60%) and milled bean flour and bean starch (85–90%) after they were cooked under similar conditions. Starch hydrolysis (%) increased significantly when the cotyledon cells in the cooked whole navy beans were disrupted using high pressure treatment (French press). The storage of freshly cooked whole beans resulted in a lower (40–45%) starch hydrolysis whereas re-heating increased the same to 70–80% during in vitro small intestinal digestion. The SEM pictures of cooked navy bean digesta after different intervals of in vitro gastric and small intestinal digestion showed that the cotyledon cell structure is maintained well throughout the digestion period. However cotyledon cells appear shrunken and developed wrinkles during in vitro digestion. Particle size analysis of cooked bean paste taken before and after the in vitro gastro-intestinal digestion showed similar particle size distributions.
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