Down-regulation of monocarboxylate transporter 1 (MCT1) gene expression in the colon of piglets is linked to bacterial protein fermentation and pro- inflammatory cytokine-mediated signalling

The present study investigated the influence of bacterial metabolites on monocarboxylate transporter 1 (MCT1) expression in pigs using in vivo, ex vivo and in vitro approaches. Piglets (n 24) were fed high-protein (26 %) or low- protein (18 %) diets with or without fermentable carbohydrates. Colonic digesta samples were analysed for a broad range of bacterial metabolites. The expression of MCT1, TNF-α, interferon γ (IFN-γ) and IL-8 was determined in colonic tissue. The expression of MCT1 was lower and of TNF-α and IL-8 was higher with high-protein diets (P< 0·05). MCT1 expression was positively correlated with l-lactate, whereas negatively correlated with NH3 and putrescine (P< 0·05). The expression of IL-8 and TNF-α was negatively correlated with l-lactate and positively correlated with NH3 and putrescine, whereas the expression of IFN-γ was positively correlated with histamine and 4-ethylphenol (P< 0·05). Subsequently, porcine colonic tissue and Caco-2 cells were incubated with Na-butyrate, NH4Cl or TNF-α as selected bacterial metabolites or mediators of inflammation. Colonic MCT1 expression was higher after incubation with Na-butyrate (P< 0·05) and lower after incubation with NH4Cl or TNF-α (P< 0·05). Incubation of Caco-2 cells with increasing concentrations of these metabolites confirmed the up-regulation of MCT1 expression by Na-butyrate (linear, P< 0·05) and down-regulation by TNF-α and NH4Cl (linear, P< 0·05). The high-protein diet decreased the expression of MCT1 in the colon of pigs, which appears to be linked to NH3- and TNF-α-mediated signalling

Estudio de la inclusión de la glicerina procedente de la elaboración de biodiesel en la alimentación de la especie porcina =Study of the inclusion of crude glycerin from biodiesel production in pig diets

El objetivo principal de esta Tesis Doctoral es evaluar la inclusión de la glicerina bruta procedente de la elaboración de biodiesel en la alimentación de la especie porcina. Con el fin de alcanzar este objetivo se diseñaron tres capítulos experimentales. En el capítulo uno se estudió el efecto de la adición de glicerina en la fabricación del pienso, así como su influencia sobre el rendimiento productivo y digestibilidad de los nutrientes en cerdos de crecimiento-cebo. Se formularon tres piensos con 0, 2.5 y 5% de glicerina bruta. El estudio de los efectos de la glicerina sobre el rendimiento productivo se realizó con 240 machos castrados, usando un programa de alimentación en dos fases (crecimiento y cebo). También se recogieron muestras de sangre para determinar las concentraciones de glucosa, fructosamina e IGF-1. Además, nueve cerdos machos fueron alojados en jaulas metabólicas para determinar los coeficientes de digestibilidad fecal, así como los balances de nitrógeno y minerales. En conclusión, la inclusión de glicerina antes de la granulación mejoró la eficiencia en la fabricación del pienso. La inclusión de hasta un 5% de glicerina bruta en el pienso de cerdos de crecimiento-cebo no tuvo efectos sobre el rendimiento productivo, metabolitos sanguíneos, digestibilidad de nutrientes y balance de nitrógeno. En el capítulo dos se determinó el efecto de la inclusión de glicerina sobre el rendimiento productivo, digestibilidad de los nutrientes y nivel de hormonas sanguíneas en cerdos de cruce de ibérico criados en régimen de explotación intensivo. Se usaron 80 cerdos cruzados (hembras ibéricas x machos Duroc) de ambos sexos durante un periodo de 101 días. Los niveles de inclusión de glicerina en el pienso fueron 0 y 10%. Los cerdos alimentados con glicerina tuvieron mayor ganancia media diaria y consumo medio diario que los del grupo control. La digestibilidad de los nutrientes no se vio afectada por la inclusión de glicerina. Sin embargo, se observó una tendencia para la grelina acilada, siendo mayor en los cerdos alimentados con glicerina. En conclusión, 100 g/kg de glicerina bruta pueden reemplazar parcialmente al trigo en el pienso de cerdos de cruce de ibérico sin afectar a la eficiencia del pienso ni a la digestibilidad de los nutrientes. En el capítulo tres, se evaluó el efecto de la adición de glicerina sobre los parámetros productivos de cerdas y camadas, y se determinaron las concentraciones plasmáticas de hormonas relacionadas con el metabolismo y la ingestión de pienso, en cerdas durante la gestación y la lactación. Sesenta y tres cerdas fueron asignadas aleatoriamente a uno de los tres tratamientos, que contenían 0, 3 o 6% de glicerina. Durante la gestación, no hubo efecto sobre ninguna variable de rendimiento, mientras que en lactación, las cerdas alimentadas con glicerina consumieron menos pienso. En la gestación, las cerdas alimentadas con glicerina mostraron menor nivel de grelina acilada y mayor nivel de leptina. En lactación, la adición de glicerina en el pienso no tuvo efecto sobre los niveles de ninguna de las hormonas medidas. Antes de la distribución del alimento, la concentración de grelina acilada estuvo positivamente correlacionada con el cortisol, tanto en gestación como en lactación. En conclusión, la inclusión de hasta un 6% de glicerina bruta en el pienso puede reemplazar parcialmente al maíz sin afectar el rendimiento de las cerdas en gestación, pero no en lactación. Nuestros resultados también sugieren la existencia de una relación entre la inclusión de glicerina en el pienso y los niveles sanguíneos de algunas hormonas reguladoras del apetito. The general aim of this PhD thesis was to evaluate the inclusion of crude glycerin from biodiesel production in pig diets. To achieve this objective, three experimental chapters were designed. In chapter one, we studied the effects of crude glycerin on pellet production efficiency and growth performance and digestibility in growing-finishing pigs. Three dietary treatments were created by addition of 0, 2.5 or 5% glycerin to diets. A performance trial was conducted with 240 barrows using a 2-phase feeding program. Also blood samples were collected to determine circulating glucose, fructosamine and IGF-1 concentrations. Additionally, nine male pigs were housed in metabolic cages to determine the coefficients of apparent fecal digestibility and nitrogen and mineral balances. In conclusion, adding crude glycerin to the diet before pelleting improved feed mill production efficiency. Up to 5% crude glycerin can be fed to growing-finishing pigs without affecting growth performance, blood metabolites, nutrient digestibility and nitrogen balance. In chapter two, we determined the effect of crude glycerin addition on the growth performance, nutrient digestibility, and blood hormone levels of Iberian crossbred pigs kept under intensive conditions. Eighty crossbred pigs (Iberian gilts Duroc boars) of both sexes were used over a period of 101. Treatments were arranged in a 2 × 2 factorial design, the factors being dietary treatment (control or 10% glycerin) and gender (barrow or gilt). Glycerin-fed pigs had higher average daily gain and average daily feed intake than pigs fed the control diet. Nutrient digestibility was not affected by dietary treatment. However, there was a tendency for acyl-ghrelin levels to be higher in glycerin-fed pigs. In conclusion, 100 g/kg of glycerin can partially replace wheat without affecting feed efficiency or nutrient digestibility in Iberian crossbred pigs. In chapter three, an experiment was conducted to evaluate the effect of dietary addition of crude glycerin on sow and litter performance, and to determine the plasmatic levels of hormones related to energy metabolism and feed intake in sows during gestation and lactation. Sixty three sows were assigned randomly to one of three dietary treatments, containing 0, 3 and 6% glycerin. During gestation, there was no effect of dietary treatment on any performance variable, while during lactation glycerin-fed sows consumed less feed than those fed the control diet. In gestation, sows fed glycerin showed lower and higher levels of acyl-ghrelin and leptin, respectively. In lactating sows, there were no differences between dietary treatments for any of the hormones measured. Before feeding, the acyl-ghrelin concentration was positively correlated with the cortisol during gestation and lactation. In conclusion, the inclusion of up to 6% crude glycerin in the diet can partially replace corn without affecting the performance of pregnant sows, but not during lactation. Our results also suggest a relationship between glycerin inclusion in the diet and the serum levels of some feed intake regulating hormones

Health relevance of intestinal protein fermentation in young pigs

The physiological role of the gastrointestinal microbiota has become an important subject of nutrition research in pigs in the past years, and the importance of intestinal microbial activity in the etiology of disease is doubtless. This review summarizes the recent knowledge related to the microbial ecology of protein fermentation and the appearance of protein-derived metabolites along the pig intestine. The amount of fermentable protein depends on factors such as dietary protein concentration, protein digestibility due to secondary or tertiary structure, the interaction with dietary compounds or anti-nutritional factors, and the secretion of endogenous proteins into the gut lumen. High protein diets increase the luminal concentrations and epithelial exposure to putatively toxic metabolites and increase the risk for post-weaning diarrhea, but the mechanisms are not yet clarified. Although the use of fermentable carbohydrates to reduce harmful protein-derived metabolites in pigs is well-established, recent studies suggest that the inclusion of fermentable carbohydrates into diets with low protein digestibility or high dietary protein level may not ameliorate all negative effects with regard to epithelial response. Based on the current knowledge, the use of diets with low levels of high-quality protein may help to reduce the risk for intestinal disease in young pigs

Diets high in heat-treated soybean meal reduce the histamine-induced epithelial response in the colon of weaned piglets and increase epithelial catabolism of histamine.

We examined the influence of dietary fermentable protein (fCP) and fermentable carbohydrates (fCHO) on the colonic epithelial response to histamine in pigs. Thirty-two weaned piglets were fed 4 diets in a 2 × 2 factorial design with low fCP/low fCHO, low fCP/high fCHO, high fCP/low fCHO and high fCP/high fCHO. After 21-23 days, the pigs were killed and tissue from the proximal colon was stimulated with carbachol, histamine, PGE2 or sodium hydrogen sulphide in Ussing chambers. Changes in short-circuit current and tissue conductance were measured. Diamine oxidase, histamine N-methyltransferase, stem cell growth factor receptor, Fc-epsilon receptor I and cystic fibrosis transmembrane conductance regulator gene expression was determined. Activities of diamine oxidase and histamine N-methyltransferase and numbers of colonic mast cells were measured. The change in the short-circuit current in response to histamine was lower (P = 0.002) and tended to be lower for PGE2 (P = 0.053) in high fCP groups compared to low fCP groups, irrespective of fCHO. Additionally, the change in tissue conductance after the application of histamine was lower (P = 0.005) in the high fCP groups. The expression of histamine N-methyltransferase mRNA (P = 0.033) and the activities of diamine oxidase (P = 0.001) and histamine N-methyltransferase (P = 0.006) were higher with high fCP in comparison with low fCP. The expression of mast cell markers, stem cell growth factor receptor (P = 0.005) and Fc-epsilon receptor I (P = 0.049) was higher with high fCP diets compared to diets low in fCP, whereas the mast cell count did not differ between groups. The expression of the cystic fibrosis transmembrane conductance regulator was reduced (P = 0.001) with high fCP diets compared to low fCP diets. The lower epithelial response to histamine and PGE2 and elevated epithelial histamine inactivation suggests an adaptation to high fCP diets