Assessing seromuscular layer and serosa removal on intestinal permeability measurements in weaned piglet everted sac segments.

The integrity of the intestinal barrier is crucial for regulating the passage of pathogens and toxins, while facilitating nutrient absorption. The everted gut sac technique, an ex-vivo technique, can be used to study interventions on barrier function. This cost-effective approach utilizes relatively large gut segments to study specific intestinal regions. Typically, intact (non-stripped) intestinal segments are used, but their use may underestimate permeability due to the medial positioning of blood vessels relative to the seromuscular layer and serosa. However, removing these layers risks physical damage, resulting in an overestimation of intestinal permeability. Therefore, we investigated the impact of stripping jejunal segments on permeability to fluorescein isothiocyanate-dextran (FITC, 4 kDa) and tetramethylrhodamine isothiocyanate-dextran (TRITC, 40 kDa), and on the absorption of glucose, lysine, and methionine in jejunal segments from 80 piglets at 8 d postweaning. Piglets were subjected to either high or low sanitary housing conditions and diets provoking intestinal protein fermentation or not, expected to influence intestinal permeability. Stripping of the seromuscular layer and serosa increased the passage of 4 kDa FITC-dextran (stripped vs. non-stripped; 1.1 vs. 0.9 pmol/cm2/min, P < 0.001), glucose (40.0 vs. 19.1 pmol/cm2/min, P < 0.001), lysine (2.5 vs. 2.0 nmol/cm2/min, P < 0.001), and methionine (4.1 vs. 2.7 pmol/cm2/min, P < 0.001). As permeability increased, the differences in methionine passage between stripped and non-stripped intestinal segments also increased (slope = 1.30, P = 0.009). The coefficients of variation were comparable between stripped and non-stripped intestines (over all treatments, stripped vs. non-stripped 38% vs. 40%). Stripping, by isolating mucosal processes without introducing additional variation, is thus recommended for studies on intestinal permeability or absorption.

The intestinal barrier is vital for nutrient passage, while impeding pathogen and toxin translocation. The everted gut sac technique is used to study intestinal permeability, incubating an isolated, everted, intestinal segment filled with buffer solution in a medium containing the substances of interest. After incubation, the translocation of the substances into the created intestinal sac can be measured. Typically, intact intestinal segments are used, but under physiological conditions, nutrients do not need to pass the seromuscular layer and serosa to enter the blood flow. Therefore, removing these layers may be preferable, but, on the other hand, also risks physical damage. This study compared the use of non-stripped vs. stripped intestinal segments. Permeability to two markers (FITC-dextran, 4kDa and TRITC-dextran, 40 kDa), and absorption of glucose, lysine, and methionine were measured in non-stripped and stripped jejunal segments obtained from 80 piglets at 8 d postweaning. The piglets were housed under different hygiene and dietary conditions, which were anticipated to alter intestinal permeability. Stripping the seromuscular layer and serosa increased the passage of FITC-dextran, glucose, lysine, and methionine, without reducing assay precision due to physical damage. Thus, removal of the seromuscular layer and serosa is preferred for studying intestinal permeability or absorption.

Effect of adding soluble viscous fibers to diets containing coarse and finely ground insoluble fibers on digesta transit behavior and nutrient digestibility in broiler chickens.

This paper aimed to study the interactive effects of the addition of soluble arabinoxylans (AX) and the particle size (PS) of soybean hulls (SBH) on digesta mean retention time (MRT) and nutrient digestibility in broiler chickens. A total of 288 one-day old Ross 308 female chicks were assigned to 32 pens (9 birds/pen) and fed a commercial starter diet for 10 d. At 10 d of age, pens were assigned to 1 of 4 dietary treatments (8 pens/diet) containing 120 g/Kg coarse or fine SBH, with or without addition of 50 g/Kg of soluble wheat AX, substituting maize starch. Titanium dioxide (4 g/Kg) and cobalt-EDTA (1 g/Kg) were added as inert markers. Excreta were quantitatively collected from d 22 to 25. Gastrointestinal tract and digesta were collected on d 28, 29, or 30. Arabinoxylans reduced the weight of the gizzard relative to body weight (RW) by 0.07% units (P = 0.005), and increased ceca RW (0.28 vs. 0.34%, P < 0.001) and length (10.45 vs. 11.21 cm/Kg BW, P < 0.001). Arabinoxylans increased digesta MRT in the crop (solids/liquids: +12 min, P < 0.05), small intestine (solids/liquids: +17 min, P < 0.01), and hindgut (liquids: +77.5 min, P < 0.05); and reduced apparent ileal digestibility (AID) and apparent total tract retention (ATTR) of DM (-5.4 and -3.9%, P < 0.001, respectively) and starch (-1.35 and -0.7%, P < 0.001, respectively). Particle size of SBH only affected the ATTR of non-starch polysaccharides, presenting higher retention values with fine SBH (-4.3%-units, P = 0.034). The addition of AX reduced AID of N by 4.3%-units, only in presence of fine SBH (interaction, P < 0.05). In conclusion, arabinoxylans greatly influenced digestion in the chicken GIT, while PS of SBH had marginal effects. Arabinoxylans reduced AID of N only with fine SBH, suggesting coarse SBH counteracted AX effects on N digestion, speculatively by modifying digesta viscosity.

Amino acid supplementation counteracts negative effects of low protein diets on tail biting in pigs more than extra environmental enrichment.

Low protein (LP) diets may increase the occurrence of damaging behaviours, like tail biting, in pigs. We investigated the effect of supplementing a LP diet with indispensable amino acids (IAA) or environmental enrichment on tail biting. Undocked pigs (n = 48 groups of 12) received either a normal protein diet (NP), a LP, LP with supplemented IAA (LP+), or LP diet with extra environmental enrichment (LP-E+) during the starter, grower, and finisher phase. Performance, activity, behaviour, and body damage were recorded. LP and LP-E+ had a lower feed intake, growth, and gain-to-feed ratio, and were more active than NP and LP+ pigs. LP-E+ pigs interacted most often with enrichment materials, followed by LP, LP+, and NP pigs. LP pigs showed more tail biting than all other groups during the starter phase and the finisher phase (tendency) compared to NP and LP+ pigs. Thus, LP-E+ only reduced tail biting in the starter phase, whereas LP+ tended to do so throughout. Tail damage was more severe in LP pigs than in NP and LP+, with LP-E+ in between. In conclusion, IAA supplementation was more effective than extra environmental enrichment in countering the negative effects of a low protein diet on tail biting in pigs.

Review: The amazing gain-to-feed ratio of newly weaned piglets: sign of efficiency or deficiency?

Shortly after weaning, piglets generally eat dry feed poorly; but nevertheless, a phenomenal gain-to-feed ratio is achieved as they gain about as much weight as they eat (150-200 g/d). The high gain-to-feed ratio, though, cannot be explained by their nutrient intake or nutrient repartitioning. Analyses based on tissue composition and bio-electrical impedance data showed that newly weaned piglets lose fat, maintain protein, and gain large amounts of water because of edema. This edema, which may well contribute up to one kg of BW, seems to be triggered by refeeding syndrome. Refeeding syndrome in adult humans occurs when subjects fast for an extended period of time (weeks) that results in downshifts in metabolic activity and concomitant shedding of phosphate (PO4), magnesium (Mg), and potassium (K) in urine. If food is abruptly reintroduced, thus, resulting in strong insulin spikes, metabolism is triggered but hampered by a lack of PO4, Mg, K, and thiamine, causing hypophosphatemia, metabolic stress, and edema. In piglets, the same process appears to happen immediately after weaning but in hours rather than weeks, possibly linked to their high metabolic rate. Refeeding syndrome can be lethal in humans but does not appear to be directly lethal in piglets. Our attempts to prevent it through altered diet composition and/or controlled feeding programs have not resulted in better performance at the end of the nursery phase. A practical ramification of weaning-induced edema is that growth and gain-to-feed ratio data immediately after weaning should be interpreted with caution. In addition, diets arguably should be formulated to not strongly trigger insulin release, while high lysine levels are not needed as the gain is not based on protein accretion.

Functional and molecular profiling of fasted piglets reveals decreased energy metabolic function and cell proliferation in the small intestine.

The small intestine requires energy to exert its important role in nutrient uptake and barrier function. Pigs are an important source of food and a model for humans. Young piglets and infants can suffer from periods of insufficient food intake. Whether this functionally affects the small intestinal epithelial cell (IEC) metabolic capacity and how this may be associated with an increased vulnerability to intestinal disease is unknown. We therefore performed a 48-h fasting intervention in young piglets. After feeding a standard weaning diet for 2 wk, 6-wk-old piglets (n = 16/group) were fasted for 48 h, and midjejunal IECs were collected upon euthanasia. Functional metabolism of isolated IECs was analyzed with the Seahorse XF analyzer and gene expression was assessed using RNA-sequencing. Fasting decreased the mitochondrial and glycolytic function of the IECs by 50% and 45%, respectively (P < 0.0001), signifying that overall metabolic function was decreased. The RNA-sequencing results corroborated our functional metabolic measurements, showing that particularly pathways related to mitochondrial energy production were decreased. Besides oxidative metabolic pathways, decreased cell-cycle progression pathways were most regulated in the fasted piglets, which were confirmed by 43% reduction of Ki67-stained cells (P < 0.05). Finally, the expression of barrier function genes was reduced upon fasting. In conclusion, we found that the decreased IEC energy metabolic function in response to fasting is supported by a decreased gene expression of mitochondrial pathways and is likely linked to the observed decreased intestinal cell proliferation and barrier function, providing insight into the vulnerability of piglets, and infants, to decreased food intake.NEW & NOTEWORTHY Fasting is identified as one of the underlying causes potentiating diarrhea development, both in piglets and humans. With this study, we demonstrate that fasting decreases the metabolism of intestinal epithelial cells, on a functional and transcriptional level. Transcriptional and histological data also show decreased intestinal cell proliferation. As such, fasting-induced intestinal energy shortage could contribute to intestinal dysfunction upon fasting.

Effects of Birthweight of Piglets in a Multi-Suckling System on Mortality, Growth Rate, Catch-Up Growth, Feed Intake and Behaviour.

Multi-suckling systems aim to improve animal welfare, but in these systems, a large variation is seen in piglet growth rate. Birthweight (BiW) plays an important role in explaining the variation in body weight (BW) gain of piglets. This study aims to investigate the relationships between BiW and piglet traits up to day 44 postpartum (p.p.). A total of 55 sows were used. The growth rate and mortality were assessed for all piglets. Feed and milk intake, behaviours, and skin lesions were assessed in four focal piglets per litter. Focal piglets were divided into four groups based on their BiW class (high BiW (HBiW) vs. low BiW (LBiW)) and growth rate class (fast vs. slow). Results showed that increased mortality was observed in piglets with a BiW below 1.1 kg. Birthweight was positively related with the number of sucklings (ß = 2.8 no./kg of BiW per 7.5 h), corresponding to milk intake (ß = 102 g/kg of BiW per day), and to a lesser extent, to the intake of sow feed (ß = 44 g/kg of BiW per day) in week 6. Birthweight was positively related with the number of skin lesions (ß = 4.3 no./kg of BiW) in week 4. We found no indications that fast-growing LBiW piglets differed from fast-growing HBiW piglets, however, fast-growing piglets of both HBiW and LBiW tended to eat more feed (485 ± 18 vs. 420 ± 17 g/day, p = 0.068), were present less often at teats of alien sows (1.1 ± 0.2 vs. 1.8 ± 0.3, p = 0.010), and had more skin lesions (9.0 ± 0.6 vs. 7.4 ± 0.4, p = 0.047), compared to slow growing piglets. Our study, thus, provides little insight into the traits that affect catchup growth in a multi-suckling environment but increases insight into the differences between fast-growing and slow-growing piglets, regardless of their birthweight class.

Effect of animal activity and air temperature on heat production, heart rate, and oxygen pulse in lactating Holstein cows.

A linear relationship between heart rate (HR) and oxygen consumption (VO2) has been reported in homeothermic animals, indicating that is possible to estimate heat production through HR measurements. This relationship may depend on the animal activity and environmental conditions. The main objective of the present study was to evaluate the effect of the air temperature and animal posture and activity on heat production and VO2 in relation to HR. In addition, as a secondary objective, the energy cost of eating and ruminating versus idling and standing versus lying down was determined. Twelve Holstein lactating cows were housed inside climate-controlled respiration chambers for 8 d, where the air temperature was gradually increased from 7 to 21°C during the night and from 16 to 30°C during the day with daily increments of 2°C for both daytime and nighttime. During the 8-d data collection period, HR and gaseous exchange measurements were performed, and animal posture and activity were recorded continuously. The oxygen pulse (O2P), which represents the amount of oxygen that is consumed by the cow per heartbeat, was calculated as the ratio between VO2 and HR. Results showed that heat production and VO2 were linearly and positively associated with HR, but this relationship largely varied between individual cows. Within the range tested, O2P was unaffected by temperature, but we detected a tendency for an interaction of O2P with the temperature range tested during the night versus during the day. This indicates that the effect of air temperature on O2P is nonlinear. Standing and eating slightly increased O2P (1.0 and 2.5%) compared with lying down and idling, respectively, whereas rumination increased O2P by 5.1% compared with idling. It was concluded that the potential bias introduced by these effects on the O2P for the application of the technique is limited. The energy cost of eating and ruminating over idling was 223 ± 11 and 45 ± 6 kJ/kg0.75 per day, respectively, whereas the energy cost of standing over lying down was 53 ± 6 kJ/kg0.75 per day. We concluded that O2P in dairy cows was slightly affected by both animal posture and activity, but remained unaffected by air temperature within 8 to 32°C. Nonlinearity of the relationship between the O2P and air temperature suggests that caution is required extrapolating O2P beyond the temperature range evaluated in our experiment.

Provision of black soldier fly larvae (Hermetia illucens) in different ways benefits broiler welfare and performance, with largest effects of scattering live larvae.

Including black soldier fly larvae (BSFL) in broiler diets has the potential to benefit broiler welfare and increase production performance, but the effects of dietary BSFL likely depend on the way BSFL are provided. In this study we aimed to discern the effects of different BSFL forms and provisioning methods by providing male broilers with no BSFL (CON), processed BSFL meal and oil incorporated in the feed pellets (INC-F), dried BSFL in the feeder on top of the feed (D-F), or dried or live BSFL scattered through the pen (D-S and L-S, respectively), and evaluating various indicators of broiler welfare and production performance. In all dietary BSFL treatments 8% of the total dietary dry matter content was replaced with BSFL. Dried and live larvae were provided in four equal daily portions at 08:00, 11:00, 14:00, and 17:00. Compared to a diet without BSFL, scattering dried or live larvae through the pen increased active behaviors, though only live larvae increased the time broilers spent standing. Broilers in the D-F, D-S and L-S treatments had higher average daily body weight gain during some periods, and they had higher final weights, despite L-S broilers having a lower total dry matter intake than CON broilers. Furthermore, the dry matter conversion ratio of INC-F, D-S and L-S broilers was reduced. At the end of the rearing period, pens in all dietary BSFL treatments had better litter quality than CON pens. Furthermore, food pad dermatitis was less severe for INC-F and D-S broilers than for CON broilers, and for L-S broilers than for broilers in all other treatments, and hock burn severity was less for L-S than for CON broilers. Broiler lameness, cleanliness, plasma natural antibody titers, and whole blood serotonin were not influenced by dietary BSFL treatment. Feather corticosterone concentrations were affected by treatment, though without any significant post-hoc differences. Our results indicate that BSFL meal and oil, and dried and live BSFL are all promising feed ingredients for broilers as they all benefit some aspects of broiler welfare and production performance. Scattering BSFL through the pen results in more welfare benefits than providing BSFL in the feeder, with live BSFL having the most beneficial effects on broiler welfare.

Galacto-oligosaccharides alleviate lung inflammation by inhibiting NLRP3 inflammasome activation in vivo and in vitro.

INTRODUCTION: The lack of effective anti-inflammatory therapies for pneumonia represents a challenge for identifying new alternatives. Non-digestible galacto-oligosaccharides (GOS) are attractive candidates due to their anti-inflammatory and immunomodulatory effects both locally and systemically. OBJECTIVES: The anti-inflammatory properties of GOS were investigated in calves with lung infections and in calf primary bronchial epithelial cells (PBECs) and human lung epithelial cells (A549). To delineate the mechanism, the potential capacity of GOS to inhibit the NLR family pyrin domain containing 3 (NLRP3) inflammasome has been investigated. METHODS: GOS were administrated orally to calves with naturally occurring lung infections during early life or used as pretreatments in cell cultures exposed to M. haemolytica, lipopolysaccharides (LPS), leukotoxin or ATP. The cell composition, cytokine/chemokine concentrations, and M. haemolytica-LPS lgG levels in broncho-alveolar lavage fluid (BALF) and blood were investigated, while the M. haemolytica positivity in BALF and bronchial mucosa was detected in vivo. Key markers of NLRP3 inflammasome activation were measured in vivo and in vitro. RESULTS: GOS reduced M. haemolytica positivity and M. haemolytica-LPS lgG levels in calves with lung infections. Regulation of immune function and suppression of inflammatory response by GOS is related to the inhibition of NLRP3 inflammasome as observed in bronchial mucosal tissue of infected calves. The M. haemolytica-induced IL-1ß production in PBECs was lowered by GOS, which was associated with NLRP3 inflammasome inhibition caused by the decreased reactive oxygen species and ATP production. GOS inhibited leukotoxin-induced ATP production in PBECs. The LPS- and ATP-induced NLRP3 inflammasome activation in PBECs and A549 cells was suppressed by GOS. CONCLUSION: GOS exert anti-inflammatory properties by inhibiting the NLRP3 inflammasome activation in vitro and in vivo, suggesting a potential role for GOS in the prevention of lung infections.

In silico modelling of protein digestion: A case study on solid/liquid and blended meals.

We present a dynamic, semi-mechanistic, compartmental protein digestion model to study the kinetics of protein digestion. The digestive system is described as a series of eight compartments: one for the stomach, one for the duodenum, two for the jejunum and four for the ileum. The digestive processes are described by a set of zero or first order differential equations. The model considers ingestion of a meal, secretion of gastric and pancreatic juices, protein hydrolysis, grinding, transit and amino acid absorption. The model was used to simulate protein digestion of a meal composed of a solid and a liquid phase or one where both phases are blended into a homogeneous phase. Luminal volumes and pH of gastric and duodenal contents were estimated for both meals. Further, gastric emptying is described as a function of the energy density of the bolus, instead of the more common mass action approach.

Assessing the Effectiveness of Providing Live Black Soldier Fly Larvae (Hermetia illucens) to Ease the Weaning Transition of Piglets.

Weaning is a stressful event for piglets, involving substantial changes to their nutritional and social environment. Providing edible enrichment around weaning may ease the weaning transition by increasing pre-weaning feed intake and improving post-weaning performance, health, behavior, and affective state. In this study, we investigated the effects of providing live black soldier fly larvae (BSFL) as edible enrichment pre- and/or post-weaning. Pre-weaning, piglets received either only creep feed (Pre-C, n = 14 litters) or creep feed and live BSFL (Pre-L, n = 15 litters) ad libitum, and post-weaning piglets either had no access to live BSFL (Post-C, n = 24 pens) or they could rotate tubes that released BSFL (Post-L, n = 24 pens) at levels up to 20% of their expected daily dry matter intake, resulting in treatments CC, CL, LC, and LL. No interaction between pre- and post-weaning treatment was found for any of the measured parameters. Before weaning, Pre-L piglets preferred to interact with larvae over creep feed, and Pre-C piglets interacted more with creep feed than Pre-L piglets. Total time spent on feed-directed behaviors did not differ. Continuous larvae provisioning increased caecum length and proximal stomach digesta pH, while it decreased the passage of glucose and fluorescein isothiocyanate through the colon wall on d3 post-weaning (CC vs. LL, n = 12 piglets/treatment). Post-weaning diarrhea and final body weight were not affected by treatment. After weaning, Pre-C piglets tended to eat more and grew marginally faster than Pre-L piglets. Post-C piglets spent more time eating and had a higher feed intake post-weaning than Post-L piglets. Based on home-pen behavioral observations, Post-L piglets actively explored and ate the larvae. Post-C piglets spent more time on exploring the environment and nosing pen mates, and they spent more time on manipulating pen mates on d8 and played more on d8 & 15 compared to Post-L piglets. Piglet responses to a novel environment and an attention bias test on d4 & 5 post-weaning were not influenced by larvae provisioning. In conclusion, pre-weaning larvae provisioning did not improve pre-weaning feed intake and post-weaning performance, however post-weaning larvae provisioning did benefit piglet behavior as less manipulation of pen mates was observed.

Galacto-oligosaccharides as an anti-bacterial and anti-invasive agent in lung infections.

Emerging antimicrobial resistance in infections asks for novel intervention strategies. Galacto-oligosaccharides (GOS) might be attractive alternatives to antibiotics due to their anti-inflammatory and anti-adhesive properties. Mannheimia haemolytica is one of the major Pasteurellaceae associated with bovine lung infections. Using M. haemolytica, we demonstrated that GOS have the capacity to reduce bacterial viability and can be used as adjuvant to improve antibiotic efficacy. Using M. haemolytica-treated primary bronchial epithelial cells (PBECs) of calves, we identified the anti-adhesive and anti-invasive activities of GOS. The observed inhibition of cytokine/chemokine release and the prevention of airway epithelial barrier dysfunction in M. haemolytica-treated PBECs by GOS might be related to the downregulation of "toll-like receptor 4/nuclear factor-κB" pathway and the anti-invasive and anti-adhesive properties of GOS. Particularly, GOS lowered lipopolysaccharides- but not flagellin-induced cytokine/chemokine release in calf and human airway epithelial cells. Finally, we performed in vivo experiments in calves and demonstrated for the first time that intranasal application of GOS can relieve lung infections/inflammation and lower M. haemolytica positivity in the lungs without affecting clinical performance. These findings not only shed light on the anti-inflammatory mechanisms of GOS during lung infections, but GOS might also be a promising anti-bacterial agent for preventing (lung) infections.

Xylan alleviates dietary fiber deprivation-induced dysbiosis by selectively promoting Bifidobacterium pseudocatenulatum in pigs.

BACKGROUND: Low dietary fiber intake has been shown to disturb the gut microbiome community, damage the mucus barrier, and promote pathogen susceptibility. However, little is known about the temporal response of the gut microbiome to dietary fiber deprivation and the recovery induced by dietary fiber inclusion in pigs. OBJECTIVE: In the present study, temporal responses of ileal and fecal microbiota to dietary fiber deprivation were profiled using an ileum cannulated growing pig model. In addition, the potential of dietary-resistant starch, ß-glucan, and xylan to alleviate gut dysbiosis throughout the gastrointestinal tract, as well as its possible mechanisms were investigated. METHODS: Six cannulated growing pigs were fed a fiber deprivation diet for 35 days. Ileal digesta and feces were collected at days 0, 7, 21, and 35 for 16S rRNA sequencing and short-chain fatty acid (SCFA) determination. Another twenty-four healthy growing pigs were assigned to one of four dietary treatments including (1) fiber-free diet, (2) resistant starch diet, (3) ß-glucan diet, and (4) xylan diet. These twenty-four pigs were fed a corresponding diet for 35 days and slaughtered. Gut microbiome and SCFA concentration were profiled along the gastrointestinal tract. RESULTS: Dietary fiber deprivation-induced consistent microbiota extinction, mainly Bifidobacterium and Lactobacillus, and decreased SCFA concentrations in both ileum and feces. The community structure partially recovered at day 35 compared with baseline while SCFA concentrations remained low. Xylan supplementation alleviated gut dysbiosis by selectively promoting Bifidobacterium pseudocatenulatum within the large intestine. SCFA concentration increased significantly after xylan supplementation and exhibited a positive association with B. pseudocatenulatum abundance. An elevated abundance of xylan degradation-related enzyme genes was also observed in the gut microbiome after xylan supplementation. In vitro growth assay further verified the xylan utilization capacity of B. pseudocatenulatum. CONCLUSIONS: Dietary fiber deprivation could induce probiotic extinction and loss of the SCFA production while potential pathogen was promoted. Xylan intervention could partially restore dietary fiber deprivation-induced gut dysbiosis through selectively promoting B. pseudocatenulatum and therefore normalizing the gut environment. These findings collectively provide evidence that dietary fiber-driven microbiota metabolism bridges the interplay between microbiome and gut health. Video abstract.

Anti-Inflammatory Properties of Fructo-Oligosaccharides in a Calf Lung Infection Model and in Mannheimia haemolytica-Infected Airway Epithelial Cells.

Emerging antimicrobial-resistant pathogens highlight the importance of developing novel interventions. Here, we investigated the anti-inflammatory properties of Fructo-oligosaccharides (FOS) in calf lung infections and in airway epithelial cells stimulated with pathogens, and/or bacterial components. During a natural exposure, 100 male calves were fed milk replacer with or without FOS for 8 weeks. Then, immune parameters and cytokine/chemokine levels in the bronchoalveolar lavage fluid (BALF) and blood were measured, and clinical scores were investigated. Calf primary bronchial epithelial cells (PBECs) and human airway epithelial cells (A549) were treated with Mannheimia haemolytica, lipopolysaccharides (LPS), and/or flagellin, with or without FOS pretreatment. Thereafter, the cytokine/chemokine levels and epithelial barrier function were examined. Relative to the control (naturally occurring lung infections), FOS-fed calves had greater macrophage numbers in BALF and lower interleukin (IL)-8, IL-6, and IL-1ß concentrations in the BALF and blood. However, FOS did not affect the clinical scores. At slaughter, FOS-fed calves had a lower severity of lung lesions compared to the control. Ex vivo, FOS prevented M. haemolytica-induced epithelial barrier dysfunction. Moreover, FOS reduced M. haemolytica- and flagellin-induced (but not LPS-induced) IL-8, TNF-α, and IL-6 release in PBECs and A549 cells. Overall, FOS had anti-inflammatory properties during the natural incidence of lung infections but had no effects on clinical symptoms.

Butyrate Alters Pyruvate Flux and Induces Lipid Accumulation in Cultured Colonocytes.

Butyrate is considered the primary energy source of colonocytes and has received wide attention due to its unique health benefits. Insight into the mechanistic effects of butyrate on cellular and metabolic function relies mainly on research in in-vitro-cultured cells. However, cells in culture differ from those in vivo in terms of metabolic phenotype and nutrient availability. For translation, it is therefore important to understand the impact of different nutrients on the effects of butyrate. We investigated the metabolic consequences of butyrate exposure under various culturing conditions, with a focus on the interaction between butyrate and glucose. To investigate whether the effects of butyrate were different between cells with high and low mitochondrial capacity, we cultured HT29 cells under either low- (0.5 mM) or high- (25 mM) glucose conditions. Low-glucose culturing increased the mitochondrial capacity of HT29 cells compared to high-glucose (25 mM) cultured HT29 cells. Long-term exposure to butyrate did not alter mitochondrial bioenergetics, but it decreased glycolytic function, regardless of glucose availability. In addition, both high- and low-glucose-grown HT29 cells showed increased lipid droplet accumulation following long-term butyrate exposure. Acute exposure of cultured cells (HT29 and Caco-2) to butyrate increased their oxygen consumption rate (OCR). A simultaneous decrease in extracellular acidification rate (ECAR) was observed. Furthermore, in the absence of glucose, OCR did not increase in response to butyrate. These results lead us to believe that butyrate itself was not responsible for the observed increase in OCR, but, instead, butyrate stimulated pyruvate flux into mitochondria. Indeed, blocking of the mitochondrial pyruvate carrier prevented a butyrate-induced increase in oxygen consumption. Taken together, our results indicate that butyrate itself is not oxidized in cultured cells but instead alters pyruvate flux and induces lipid accumulation.

Providing live black soldier fly larvae (Hermetia illucens) improves welfare while maintaining performance of piglets post-weaning.

During weaning, piglets experience concurrent social, physical, and nutritional stressors. Consequently, piglets often have poor feed intake and display increased oral manipulative behaviours post-weaning, indicative of compromised welfare. Black soldier fly larvae (BSFL) possess many attractive properties for pigs and could therefore function as effective edible enrichment, potentially alleviating weaning stress by facilitating exploration and promoting feed intake. In this study, pairs of piglets received a small amount of either live BSFL or wood shavings (8 pens/treatment) scattered throughout the pen twice a day for 11 days after weaning. Home-pen behaviour was scored by instantaneous scan sampling on day 2, 5 and 8, and behavioural responses to a novel environment and novel object were scored on day 10/11. Performance-related parameters were observed regularly. Larvae provisioning increased floor-directed exploration and decreased object-directed exploration, pig-directed oral manipulation, fighting and eating of pellets, and reduced neophobia towards a novel object. Pellet intake was significantly decreased by BSFL provisioning during day 4-11 post-weaning, although feed and net energy intake including BSFL never differed between treatments. BSFL provisioning did not influence piglet growth, feed efficiency, energy efficiency, and faecal consistency. To conclude, live BSFL provisioning positively affected post-weaning piglet behaviour while maintaining performance.

Effect of solid feed level and types of roughage on passage kinetics of milk replacer, concentrate, and roughage in veal calves.

This study aimed (1) to provide estimates of total mean retention times of milk replacer (MR), concentrates, and roughage in veal calves fed a mixed diet; (2) to determine the effect of level and type of solid feed (SF) on passage kinetics of MR, concentrates, and roughages in veal calves; and (3) to compare passage kinetics in veal calves using the fecal excretion curves of indigestible markers and a noninvasive 13C tracer breath test approach to determine whether the latter technique can serve as an alternative. At the start of the trial, 48 Holstein-Friesian calves (6 wk of age; 68 ± 7.7 kg of body weight; BW) were assigned to 1 of 4 dietary treatments (for statistical analysis, only 39 calf observations were used). Three treatments contained chopped wheat straw as roughage in the SF mixture in a concentrate:roughage ratio of 90:10 (dry matter basis). The SF level was 20 g/kg of metabolic BW per day (low straw), 30 g/kg of metabolic BW per day (middle straw), or 40 g/kg of metabolic BW per day (high straw). The fourth treatment (high hay) contained long perennial ryegrass hay as roughage in the SF mixture in a concentrate:roughage ratio of 70:30 (dry matter basis, at 40 g/kg of metabolic BW per day). The quantity of MR was fixed for the high straw treatment, whereas the amount of MR for the other treatments during the adaptation period was adjusted based on a pair gain strategy (i.e., exchanging ration components but keeping similar net energy). At the end of the adaptation period, calves ranged from 12 to 15 wk of age with an average BW of 123 ± 8.6 kg. Passage kinetics of concentrates were estimated by measuring 13C enrichment excess of CO2 in breath from a pulsed-dose of [1-13C]octanoate. Passage kinetics of roughage, concentrates, and MR were also estimated using fecal excretion curves obtained after ingestion of chromium-mordanted roughage, Yb2O3, and Co-EDTA, respectively. We conclude that [1-13C]octanoate cannot serve as a measure for oro-duodenal transit of concentrates because of unrealistic estimates. Based on the fecal excretion curves, we concluded that the total mean retention time of MR (i.e., time to peak; the moment that the excretion curve reaches peak concentration) was, on average, 12.4 h, and that the passage kinetics of MR was not affected by the level or type of SF. The mean retention time of concentrates was shorter (21.4 h) than that of both straw (59.1 h) and hay (36.8 h), and was not affected by the level or type of SF. Also, the mean retention time of the slowest compartment (i.e., the rumen) was shorter for concentrates (39.6 h) than that of straw (110.0 h) and hay (59.2 h). Contrary, the passage of roughage was affected by level and type of SF. Long hay increased time to peak by 22.3 h and decreased ruminal mean retention time by 50.8 h relative to chopped straw, indicating that the passage rate of long hay is faster than that of chopped straw. We conclude that the level and type of SF only affects the passage kinetics of roughage and not that of MR and concentrates.

Black soldier fly reared on pig manure: Bioconversion efficiencies, nutrients in the residual material, greenhouse gas and ammonia emissions.

There is an increased interest for using insects, such as the black soldier fly, to treat surplus manure and upcycle nutrients into the food system. Understanding the influence that BSFL have on nutrient flows and nutrient losses during manure bioconversion is key for sustainability assessments. Here we quantified and compared nutrient balances, nutrient levels in residual materials and emissions of greenhouse gases and ammonia between manure incubated with black soldier fly larvae (BSFL) and manure without BSFL, during a 9-day experimental period. We obtained high analytical recoveries, ranging between 95 and 103%. We found that of the pig manure supplied, 12.5% of dry matter (DM), 13% of carbon, 25% of nitrogen, 14% of energy, 8.5% of phosphorus and 9% of potassium was stored in BSFL body mass. When BSFL were present, more carbon dioxide (247 vs 148 g/kg of DM manure) and ammonia-nitrogen (7 vs 4.5 g/kg of DM manure) emitted than when larvae were absent. Methane, which was the main contributor to greenhouse gas emissions, was produced at the same levels (1.3 vs 1.1 g/kg of DM manure) in both treatments, indicating the main role that manure microbial methane emissions play. Nitrous oxide was negligible in both treatments. The uptake of nutrients by the larvae and the higher carbon dioxide and ammonia emissions modified the nutrient composition of the residual material substantially relative to the fresh manure. Our study provides a reliable basis to quantify the environmental impact of using BSFL in future life cycle assessments.

ASAS-NANP symposium: digestion kinetics in pigs: the next step in feed evaluation and a ready-to-use modeling exercise.

Growing importance of upcycling agricultural by-products, food waste, and food processing by-products through livestock production strongly increased the variation in the nutritional quality of feed ingredients. Traditionally, feed ingredients are evaluated based on their measured extent of digestion. Awareness increases that in addition to the extent, the kinetics of digestion affects the metabolic fate of nutrients after absorption. Together with a growing body of evidence of complex interactions occurring within the lumen of the digestive tract, this urges the need of developing new approaches for feed evaluation. In a recently developed approach, we propose combining in vitro and in silico methods for feed ingredient evaluation. First steps in the development of such a systems were made by (1) evaluating in vitro the digestion potential of feed ingredients, regarding this as true ingredient properties and (2) predicting in silico the digestive processes like digesta transit, nutrient hydrolysis and absorption using dynamic, mechanistic modeling. This approach allows to evaluate to what extent the digestion potential of each ingredient is exploited in the digestive tract. Future efforts should focus on modeling digesta physicochemical properties and transit, applying in vitro digestion kinetic data of feed ingredients in mechanistic models, and generating reliable in vivo data on nutrient absorption kinetics across feed ingredients. The dynamic modeling approach is illustrated by a description of a modeling exercise that can be used for teaching purposes in digestive physiology or animal nutrition courses. A complete set of equations is provided as an on-line supplement, and can be built in modeling software that is freely available. Alternatively, the model can be constructed using any modeling software that enables the use of numerical integration methods.