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The reduction of antimicrobial resistance is a major challenge for the scientific community. In a few decades, infections by resistant bacteria are forecasted to be the main cause of death in the world. The withdrawal of antibiotics as growth promoters and their preventive use in animal production is essential to avoid these resistances, but this may impair productivity and health due to the increase in gut inflammation. This reduction in productivity aggravates the problem of increasing meat demand in developing countries and limits the availability of raw materials. Probiotics are promising products to address this challenge due to their beneficial effects on microbiota composition, mucosal barrier integrity, and immune system to control inflammation. Although many modes of action have been demonstrated, the scientific community is not able to describe the specific effects that a probiotic should induce on the host to maximize both productivity and animal health. First, it may be necessary to define what are the innate immune pathways acting in the gut that optimize productivity and health and to then investigate which probiotic strain is able to induce the specific effect needed. This review describes several gaps in the knowledge of host-microbiota-pathogen interaction and the related mechanisms involved in the inflammatory response not demonstrated yet in poultry.

Objective: This study aimed to explore the effects of spray-dried porcine plasma (SDPP) in pre-starter feed of piglets on performance, fecal consistency, gut integrity biomarkers, and gene expression patterns related to intestinal function.Methods: Ninety piglets (18 pens; 5 pigs/pen; 8.16±1.29 kg initial body weight) were offered pre-starter feed with either soy protein concentrate (control) or SDPP for 14 d postweaning, and a common commercial starter feed between 14 and 35 d. Pigs’ performance was recorded at 0, 7, 14 and 35 d of trial and their fecal consistency was assessed on the first 2 weeks. At 7 d, one piglet per pen (18 in total) was sampled for blood, intestinal mucosa, and bile. Blood serum calprotectin and citrulline and bile sIgA were quantified with ELISA, and gene expression in the mucosa from ileum, jejunum, and caecum was analyzed with high-throughput microfluidic technology.Results: Relative to control, SDPP improved feed intake (215 vs 280 g/d; p<0.05), weight gain (133 vs. 205 g/d; p<0.05) and gain-to-feed ratio (0.61 vs. 0.74; p<0.05) between d 0 to 7. Serum calprotectin and citrulline, and bile sIgA at d 7 were not affected. Piglets fed SDPP had higher expressions of IL-1β (p = 0.033) in jejunal mucosa, and of IL-1β (p = 0.018), IL-8/CXCL8 (p = 0.010), GBP1 (p = 0.014) and TGF-β1 (p = 0.015) in ileal mucosa, at 7 d post-weaning. No effects on fecal scores were observed.Conclusion: It is concluded that the administration of SDPP during the pre-starter phase improves piglet’s performance during the first week post-weaning. These SDPP associated benefits appear to have been achieved through the modulation of gut homeostasis, potentially involving the regulation of inflammatory factors in the small intestinal mucosa.

The mushroom industry generates by-products often classified as waste, making waste management a significant concern. To address this challenge and meet the growing demand for alternative protein sources in aquafeeds, this study evaluated the in vitro and in vivo digestibility of mushroom meals derived from three commercially cultivated species: Agaricus bisporus (AB), Lentinula edodes (LE), and Pleurotus ostreatus (PO) in rainbow trout ( Oncorhynchus mykiss ), as well as key performance indicators associated to growth, feed efficiency and body condition. In vitro digestibility was evaluated using semi-permeable membrane bioreactors by measuring liberated amino acids, while in vivo digestibility coefficients (ADCs) and key performance indicator (KPI) analyses were determined by feeding O. mykiss with diets containing AB, LE and PO meals for 42 days. Results showed that AB meal had similar in vitro digestibility to fish meal ( p > 0.05), while LE and PO displayed intermediate and lowest digestibility values, respectively. Conversely, the in vivo ADCs of LE and PO meals was similar to the control ( p > 0.05), whereas AB meal showed the lowest ADCs. Growth performance, somatic indices, blood biochemistry, whole-body composition, and digestive enzyme activities of O. mykiss were unaffected by AB, LE and PO diets ( p > 0.05), but hepatic carbohydrate content and vacuolization increased in LE fed group ( p < 0.05). Overall, although the digestibility of the three meals differed in vitro and in vivo , their crude protein ADC values were high (diet: > 90%; ingredient: > 77%) and did not compromise O. mykiss growth or feed efficiency. Thus, mushroom by-products may serve as alternative protein ingredients for aquafeeds.

Phosphorous is essential for many metabolic functions and the constitution of bones. Poultry have limited ability to use phosphorous from diets, which is mainly excreted and causes environmental concern. For this reason, diets are commonly supplemented with inorganic phosphorus and phytases. It has been suggested that chickens can adapt to an early nutrient restriction by increasing its efficiency of utilization, an adaptation that has been defined as nutritional conditioning. The aim of this study was to investigate a strategy of phosphorous nutritional conditioning by feeding low phosphorous diets during the first week of life as a strategy to improve the efficiency of phosphorous utilization later in life. To test this, 600 male broiler chickens were fed either a standard (control group) or a phosphorous-deficient diet (conditioned group) during the first week of life. Later in life, the effect of conditioning was tested using standard or P-deficient diets during the finishing phase (21–43 d). Conditioning did not affect overall performance, despite finding evidence for reduced relative phosphorous excretion between days 19 to 21, increased duodenal gene expression for the phosphorous transporter SLC34A2 at day 30 (−6% and +17%, respectively), and tendencies for improved phosphorous digestibility (+7%) and tibia mineralization (+6%) at the end of the trial. It is concluded that phosphorous nutritional conditioning early in life can increase subsequent dietary phosphorous utilization and bone mineralization in poultry, although it may not be able to counteract severe phosphorous deficiencies. Further research is required to assess the extent to which phosphorous supplementation in post-conditioning diets may be reduced with this strategy without compromising performance.

The author(s) declare that financial support was received for the research and/or publication of this article. ZN received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 945413 and from the Universitat Rovira i Virgili (URV) and the Institute of Agrifood Research and Technology (IRTA).

Phosphorus (P) is an essential mineral for growing piglets, which is poorly accessible in vegetable feedstuffs as it is stored as phytates. Thus, phytase supplementation is essential to increase P availability. Two experiments were conducted to evaluate a novel 6-phytase (EC 3.1.3.26) in weaned pigs fed low-P diets. In each experiment, one hundred and twenty piglets were fed a positive control (PC; adequate in Ca and P), a negative control (NC; limiting in Ca and P), or NC supplemented with 125, 250, or 500 FTU/kg of phytase (NC125, NC250, and NC500, respectively). P content was lower in diets of Experiment 1 than diets of Experiment 2. In Experiment 1, piglets offered PC or phytase diets had higher growth and efficiency compared with NC diets. In Experiment 2, similar effects were obtained, but the effects were less significant. In both experiments, P and Ca ATTD and bone density were significantly increased with phytase supplementation. Moreover, PC and NC500 had higher P concentrations and lower alkaline phosphatase activity in plasma than NC. To conclude, supplementation with the new 6-phytase at doses up to 500 FTU/kg enhanced P utilization, growth performance, and bone density in piglets fed P-limiting diets.

The present study aimed to investigate the effect of age, breed, and sex of broilers, as well as a probiotic or phytobiotic product on mucosal morphology, bacterial metabolites, and immune traits in the ileum of broilers. A total of 2,880 one-day-old male and female broiler chicks from two breeds (Ross308® and Cobb500®) were randomly assigned to 72 pens. Broilers were offered a wheat-soybean diet without (CO), or with either a probiotic (PO; 2.4 × 109 CFU/kg of Bacillus subtilis DSM32324 and DSM32325 and B. amyloliquefaciens DSM25840) or a phytobiotic (PY; grape extract, 165 ppm procyanidin and 585 ppm polyphenols of the diet) product. The trial was conducted with a 3 × 2 × 2 factorial arrangement of diet, breed, and sex in a completely randomized design (6 replicate-pens per treatment). At day 7, 21, and 35, one chicken per pen was slaughtered for collecting ileal tissue to evaluate of histomorphology and mRNA expression, as well as ileal digesta to measure bacterial metabolites. Data were subjected to ANOVA (the main factors; age, diet, breed, and sex) and Four-Way ANOVA (interactions) using GLM procedure. Overall, the concentration of acetate and total short chain fatty acids reached the peak and lactate decreased to its lowest on day 21, but their concentrations at day 7 and 35 were similar (p > 0.05). Spermine, spermidine, and ammonia decreased after day 7, while putrescine and cadaverine increased after day 21 (p < 0.05). mRNA expression of cytokines, mucin 2 (MUC2) and claudin 5 (CLDN5) was similar; increased from day 7 to 21 and decreased afterward (p < 0.05). Villus height, crypt depth and villus surface area increased with age (p < 0.05). Acidic goblet cells (GC) number and density increased after day 21 (p < 0.05). Ross broilers showed higher D-lactate concentration and IFN-γ expression, while Cobb broilers had greater IL-4, IL-6 and TNF-α expression and higher total GC number (p < 0.05). Female displayed higher villus height and GC number and density (mixed and total GC) than male (p < 0.05). The effect of dietary treatment was not found on any investigated variables (p > 0.05). In conclusion, aging of broilers affected ileal histomorphology, cytokine expression, and barrier integrity, as well as bacterial activity. These observed impacts could be attributed to host-microbiota interaction and the direct effects of bacterial metabolites on intestinal cells and immune system.

We report the immunogenicity of three dendrimeric peptide vaccine candidates for classical swine fever virus (CSFV). Each dendrimeric construct contained four copies of a B-cell epitope from the E2 glycoprotein of CSFV [construct 1: E2 (694–712); 2: E2 (712–727); 3: E2 (829–842)] joined to a T-cell epitope from the NS3 protein (residues 1446–1460). Intramuscular immunization of domestic pigs with the different constructs significantly reduced the clinical score after lethal challenge with CSFV. In contrast, control pigs developed severe clinical signs of the disease. All pigs vaccinated with construct 1, containing a B-cell epitope from the E2 B–C domain, developed an antibody response that recognized not only the original dendrimeric immunogen but also its constituting E2 epitope in linear form, albeit no neutralizing antibodies were detected prior to viral challenge. Two of these pigs were partially protected, which associated with the induction of IFN-γ producing cells and of neutralizing antibodies upon challenge. Interestingly, the serological response elicited by construct 1 lacked antibodies to E2 A domain, used as infection markers. The dendrimeric approach could therefore provide a basis for the development of CSFV marker (DIVA) vaccines, and contribute to a better understanding of the immune responses against CSFV.