In vitro digestion studies demonstrate large potential to gain more and quicker insights into the underlying mechanisms of feed additives, allowing the optimization of feed design. Unfortunately, current in vitro digestion models relevant for broiler chickens lack sufficient description in terms of protocols and standardisation used. Furthermore, no distinction is made between the different life phases of these animals (starter, grower, and finisher). Hence, our research aimed to establish adapted in vitro digestion conditions, corresponding to the 3 life phases in broilers, with specific focus on lipid digestion. The effect of 3 different bile salt concentrations of 2, 10, and 20 mM, and 3 different lipase activities of 5, 20, and 100 U/mL, on in vitro lipid digestion kinetics were evaluated using a full factorial design. These values were selected to represent starter, grower, and finisher birds, respectively. Our findings showed that the extent of lipid digestion was mainly influenced by lipase activity. The rate of lipid digestion was affected by an interplay between bile salt concentration and lipase activity, due to possible lipase inhibition at certain bile salt concentrations. Overall, this work resulted in 3 in vitro lipid digestion models representative for starter, grower, and finisher birds. In conclusion, this research showed the impact of adapted in vitro digestion conditions on lipid digestion kinetics and thus the need for these conditions relevant for each life phase of broilers.

This literature review evaluates the absorption of methionine (Met) sources such as 2-hydroxy-4-methylthiobutyric acid (HMTBa), its calcium salts (HMTBa-Ca), and DL-methionine (DL-Met) by focusing on the state of knowledge regarding the absorption mechanism, experimental methodology, and factors affecting their absorption. The 2 Met sources differ in mechanism and site of absorption due to differences in their chemical characteristics and enzymatic conversion. This review addresses diffusion- and transport-mediated absorption systems for amino acids and carboxylic compounds, best elucidated by in vitro, ex vivo, and in vivo experimental models. Opportunities and limitations in the use of radioisotopes to depict absorption sites as well as host and microbial metabolism are described. Physiological and environmental conditions that lead to changes in gut absorptive capacity and the impact of Met source absorption are also evaluated. This review concludes that any comparison between HMTBa and DL-Met should consider their different behaviors during the absorption phase. Hence, the chemical characteristics of these 2 molecules entail different absorption sites and mechanisms, from passive absorption in the case of HMTBa and HMTBa-Ca to active transporters for DL-Met, HMTBa, and HMTBa-Ca. In addition, the different conversion modes of these 2 molecules further differentiate their absorption modes. Considering these important differences, it is easier to understand the apparent divergence between the conclusions of existing publications. When comparing these 2 molecules, it is recommended to properly adapt to the conditions under which the absorption of Met sources is evaluated.

Due to diminishing fish meal (FM) supplies, superb protein (PRO) sources are needed for aquaculture, such as soy-based PRO. However, these can cause enteritis and even intestinal injury in fish when used at high proportions in feed. This research examines the effects of substituting soybean protein concentrate (SPC) for FM on the growth performance and intestinal balance of pearl gentian groupers and investigates the mechanism of SPC-induced enteritis. Experimental fish (n = 720) were fed 1 of 3 following diets: (1) a 50% FM diet (control), (2) a diet with 20% of the FM substituted with SPC (group SPC20), and (3) a 40% SPC-substituted diet (SPC40). Fish were fed for 10 wk iso-nitrogenous (50% PRO) and iso-lipidic (10% lipid) diets. Groups SPC20 and SPC40 showed significantly lower developmental performance and intestinal structures than control. Group SPC40 had significantly higher expressions of proinflammatory-related genes, such as interleukin 1β (IL1β), IL12, IL17 and tumor necrosis factor α and significantly lower expressions of anti-inflammatory-related genes, such as IL5, IL10 and transforming growth factor β1. Biochemical and 16S high-throughput sequencing showed that the abundance and functions of intestinal flora in group SPC40 were significantly affected (P < 0.05), and there were significant correlations between operational taxonomic unit abundance variations and inflammatory gene expressions at genus level (P < 0.05). The second- and third-generation full-length transcriptome sequence was used to analyze the mechanism of SPC-induced enteritis in pearl gentian groupers, which showed that enteritis induced by SPC may be caused by disturbances to intestinal immune function induced by an imbalance in intestinal nutrition and metabolism, such as the intestinal immunity network for IgA production pathway. However, it remains unclear as to which intestinal immune or nutritional imbalance is most important in enteritis development. This study provides a basis for further research into soy PRO-related enteritis in fish.

Zearalenone (ZEA), a mycotoxin produced mainly by fungi belonging to Fusarium species in foods and feeds, causes a serious hazard to humans and animals. Numerous studies have revealed that ingesting ZEA can disrupt the reproductive function and impair the reproductive process in animals. This experiment was to investigate the toxicological effect and the mechanism of ZEA exposure on reproduction in pigs during early stages of pregnancy. In the present study, we treated with 0 to 80 μmol/L ZEA for 12 or 24 h in trophoblast ectoderm (pTr) cells. The results showed that ZEA had significantly decreased cell proliferation (P < 0.05), which was accompanied by DNA damage-related cell cycle arrest at G2/M phase, activation of the apoptosis and endoplasmic reticulum (ER) stress, as well as impairment of barrier function (P < 0.05). Western blot analysis and transmission electron microscopy (TEM) showed that exposure to ZEA can activation of autophagy in pTr cells. Importantly, pretreatment with chloroquine (CQ) or 3-methyladenine (3-MA) led to increased apoptosis in pTr cells. Interestingly, pTr cells pretreated with 4-phenylbutyric acid (4-PBA), an inhibitor of ER stress, resulted in reduced cell death in pTr cells, indicating a critical role for ER stress in the activation of autophagy. In conclusion, these results reveal that ZEA-triggered ER stress is critical for the cell fate decision of pTr cells during early porcine embryonic development. Application of small molecules with ability of blocking ER stress might be ther apeutic option to reduce the deleterious effect of ZEA in pregnant animals.

Effects of antimicrobial peptides (AMP) added to diets on aquatic animal health and body function are influenced by multiple factors such as animal species, initial body weight, the dosage of AMP and feeding duration. However, there is limited knowledge on the relationship between these factors and the body function of aquatic animals. Here, we aimed to perform multiple meta-analyses to investigate the effects of dietary AMP on growth performance (feed conversion ratio [FCR], specific growth rate [SGR]), enzyme activity (superoxide dismutase activity [SOD], lysozyme activity [LSA]), disease resistance (cumulative survival rate [CSR], the expression of immune-related genes [GENE]) and the abundance of gut microbiota (MICRO) from a pool of empirical studies. Additionally, the dose-effect model was applied to determine the optimal AMP dose, initial body weight and feeding duration to maximize body function. To conduct the meta-analyses, we included 34 publications that estimated 705 effect sizes across 21 fish, 2 shrimp and 2 shellfish species. The results confirmed that the inclusion of AMP in the diet can significantly improve SGR, SOD, LSA, CSR and GENE and decrease FCR for aquatic animals. Interestingly, our findings implied a slight positive effect of AMP on MICRO albeit with a limited number of studies available on fish gut microbial communities. Although no significant linear or quadratic relationship was predicted by meta-regression, the dose-effect indicated that the optimal AMP doses for FCR, SGR, SOD and LSA were 707.5, 750.0, 1,050.0 and 937.5mg/kg, respectively. Taken together, fish with an initial body weight of 30g could be fed with a dose of 600 to 800mg/kg for 2 mo when AMP-supplemented diets were applied in aquaculture, which can effectively improve body function and health while lowering aquafeed costs. In addition, more studies should address fish gut microbiota to delimitate the influence of dietary AMP on MICRO in the future.

This study was to determine the effects of riboflavin deficiency (RD) on intestinal development, jejunum mucosa proteome, cecal short-chain fatty acids (SCFA) profiling, and cecal microbial diversity and community of starter Pekin ducks. Male white Pekin ducks (1 d old, n = 240) were allocated into 2 groups, with 12 replicates and 10 birds per replicate in each group. For 21 d, all ducks had ad libitum access to either an RD or a riboflavin adequate (control, CON) diet, formulated by supplementing a basal diet with 0 or 10 mg riboflavin per kg of diet, respectively. Compared to the CON group, growth retardation, high mortality, and poor riboflavin status were observed in the RD group. Furthermore, RD reduced the villus height and the ratio of villus height to crypt depth of jejunum and ileum (P < 0.05), indicating morphological alterations of the small intestine. In addition, dietary RD enhanced relative cecum weight and decreased cecal SCFA concentrations (P < 0.05), including propionate, isobutyrate, butyrate, and isovalerate. The jejunum mucosa proteomics showed that 208 proteins were upregulated and 229 proteins were downregulated in the RD group compared to those in the CON group. Among these, RD mainly suppressed intestinal absorption and energy generation processes such as glycolysis and gluconeogenesis, fatty acid beta oxidation, tricarboxylic acid cycle, and oxidative phosphorylation, leading to impaired ATP generation. In addition, RD decreased the community richness and diversity of the bacterial community in the cecum of ducks. Specifically, RD reduced the abundance of butyrateproducing bacteria in the cecum (P < 0.05), such as Eubacterium coprostanoligenes, Prevotella and Faecalibacterium. Dietary RD resulted in growth depression and intestinal hypofunction of Pekin ducks, which could be associated with impaired intestinal absorption and energy generation processes in intestinal mucosa, as well as gut microbiota dysbiosis. These findings contribute to our understanding of the mechanisms of intestinal hypofunction due to RD.

The effects of age, body weight (BW), and backfat thickness (BF) of replacement gilts at first estrus and first mating on their subsequent reproductive performance and retention of their first 2 parities as sows was evaluated. A total of 3,025 Danish replacement gilts were categorized by farm (allocated to 4 farms), cross combination, age, BW and BF at first estrus and first mating, estrous cycle number at first mating, and flush feeding before first mating. The result shows that all the factors mentioned above were significantly associated with reproductive performance and retention rates of the first 2 parities. Farm 3 had more piglets born alive per litter (BA) (P < 0.05). Farms 3 and 4 had more healthy piglets per litter (HP) (P < 0.05). Farm 4 had the most piglets weaned per litter (PW) (P < 0.05). Landrace × Landrace × Yorkshire (L × L × Y) replacement gilts had the most total piglets born per litter (TB), BA, HP, PW and a higher retention rate of the 2 parities than Landrace × Yorkshire (L × Y) replacement gilts (P < 0.05). In addition, flush feeding before first mating had the most TB, BA, HP, PW, and a higher retention rate of the 2 parities than no flush feeding (P < 0.05). Because the effects of replacement gilts rearing parameters on reproductive performance traits differed, we used 100 replacement gilts as a unit and the total number of weaned piglets from the first 2 parities as a new index. Replacement gilts undergoing their first estrus between 180 and 210 d of age at 115 to 124.9 kg BW and 14 to 15 mm BF had significantly higher reproductive indexes for their first 2 parities per 100 replacement gilts. Replacement gilts that mated between 210 and 230 d of age at 140 to 149.9 kg BW and 15 to 16 mm BF had optimal reproductive indexes. These results provide a new insight into the complex relationships among these reproductive performance traits and may help guide successful management of replacement gilts as a pivotal starting point for future fertility and longevity of rearing herds.

Lysine is one of the essential amino acids and plays a vital role in the growth, development and health of pigs. Blood lysine concentration is a direct indication of lysine status; however, current methods can not satisfy the demands for rapid and on-site lysine concentration measurement of swine serum. Here, we developed blue-emissive nitrogen-doped carbon dots as a fluorescence probe for the determination of lysine with high fluorescence quantum yield, stability, sensitivity and specificity. The carbon dots were entrapped within hydrogel microstructures to fabricate microfluidic chips for rapid assay for lysine quantification. We further developed an imaging attachment to integrate the microfluidic chip and a smartphone into a portable point-of-care testing platform. This platform requires only 3 μL sample and has a linear detection range of 25 to 300 μmol/L with a limit of detection less than 16 μmol/L, which covers the normal range of lysine concentration in swine serum. We tested lysine concentration in swine serum using this platform with high accuracy, low sample consumption, and within 3 min. Together, these results may provide a rapid and portable platform for dynamic monitoring of swine lysine status and contribute to precise feed formula modulation with low-protein diet strategy.

Colibacillosis caused by avian pathogenic Escherichia coli (APEC) is a very prevalent disease in poultry farms in China. The exploration of effective non-antibiotic substances is of great significance for the control of APEC infections. This experiment evaluated the efficacy of coated essential oil and organic acid (EOA) supplementation to prevent E. coli O78 infection in _broiler chickens. A total of 288 one-day-old male broiler chicks were randomly distributed into 4 groups with 6 replicates per group. Chickens were fed a diet either supplemented with EOA (500 mg/kg feed) or not, and either uninfected or infected with E. coli O78 intratracheally. Results showed that E. coli O78 infection reduced body weight gain, increased mortality and the ratio of feed to gain along with cecal and liver E. coli load, damaged gut mucosa, induced local and systemic inflammation, and altered cecal microbial composition, diversity and function (P < 0.05). Supplemental EOA improved feed conversion efficiency, lowered gross lesion scores and cecal E. coli population, enhanced intestinal goblet cells and serum IgG concentration, and tended to decrease serum IL-12 production (P < 0.05). Essential oil and organic acid addition downregulated IFN-γ mRNA, tended to decrease mucin-2 mRNA levels while upregulating IL-10 mRNA, and tended to increase ZO-1 gene expression in the jejuna of infected birds at 7 d after E. coli O78 challenge (P < 0.05). The 16S rRNA gene sequencing indicated that both EOA addition and E. coli O78 challenge altered the diversity and composition of the cecal microbiota community. Furthermore, infected birds fed EOA showed decreased Bacteroidetes and genus Lactobacillus abundance compared with the infected control. LEfSe analysis showed that Firmicutes, Ruminococcaceae, Clostridiales, Clostridia, Lactobacillus, Lactobacilaceae, and cc-115 were enriched in the non-infected but EOA-treated group (P < 0.05). Collectively, dietary EOA supplementation could mildly alleviate E. coli-induced gut injury and inflammation.

This study was to investigate time-course effects of different types of dietary fiber on the energy values, fecal microbiota and short-chain fatty acid (SCFA) concentration in growing pigs. A total of 24 barrows (initial body weight, 19.8 ± 0.5kg) were assigned to 4 dietary treatments based on body weight (BW) in a completely randomized design, including a basal diet (CON) and 3 fiber-rich diets replacing corn, soybean meal and soybean oil in the CON diet with 20% sugar beet pulp (SBP), defatted rice bran (DFRB) or soybean hull (SBH), respectively. Fresh feces were sampled on d 7, 14 and 21, followed by 5 d total feces and urine collections. The results showed that there were no differences in DE and ME between any of the fiber ingredients on d 7, 14 or 21. However, fiber inclusion decreased the DE and ME of the diet (P < 0.05) regardless of the time effect. Principal coordinate analysis (PCoA) revealed distinctly different microbial communities on the DFRB diet and SBH diet across different times (P < 0.05) and the fecal microbiota of the 4 diet groups demonstrated notably distinct clusters at each time point (P < 0.05). With adaptation time increased from 7 to 21 d, cellulose-degrading bacteria and SCFA-producing bacteria (e.g., Ruminococcaceae_UCG-014, Rikenellaceae_RC9_gut_group and Bifidobacterium) increased in the fiber inclusion diets, and pathogenic genera (e.g., Streptococcus and Selenomonas) were increased in the basal diet (P < 0.05). Furthermore, the gut microbiota of growing pigs adapted more easily and quickly to the SBP diet compared to the DFRB diet, as reflected by the concentration of propionate, butyrate, isovalerate and total SCFA which increased with time for growing pigs fed the DFRB diet (P < 0.05). Collectively, our results indicated at least 7 d adaptation was required to evaluate the energy values of fiber-rich ingredients, as the hindgut microbiota of growing pigs may need more time to adapt to a high fiber diet, especially for insoluble dietary fiber.