Dietary Nitrate: Effects on the health of weaning pigs and Antimicrobial activity on seven probiotic Bifidobacterium spp. strains

The potential role of nitrite as an antimicrobial substance in the stomach may be of some importance in the ecology of the gastrointestinal tract and in host physiology. It has been shown that nitrite, under the acidic conditions of the stomach, may kill gut pathogens like Salmonella enteritidis, Escherichia coli, Salmonella typhimurium, and Yersinia enterocolitica, whereas acid alone has only a bacteriostatic effect. An in vivo study was conducted in order to assess the effects of dietary nitrate on microbiota and on the health of the gut (particularly in the stomach and small intestine). 96 weaning pigs were fed a diet containing high nitrate levels (15 mg and 150 mg) and then challenged with Salmonella enterica serovar typhimurium. Differences in composition of the gut microbiota were assessed by analysing samples from the pigs: To date analysis of 48 pigs has been completed.. Preliminary results demonstrated no effect on the population densities of microbial groups either from the challenge or from nitrate intake. However, increasing the time from challenge decreased either the counts of LAB in the stomach and jejunum or of clostridia in the stomach. Bifidobacteria also decreased in the stomach contents as nitrate supplementation increased. Supplementing the feedstuff with high dietary nitrate intake and then challenging with Salmonella did not affect the gastric pH or the degree of ulceration in the pigs. The synergistic bactericidal effects of pH, nitrite and thiocyanate on seven probiotic Bifidobacterium spp. strains were also investigated in an in vitro study. The results of the in vitro study demonstrated that an inhibitory effect exists on the seven probiotic bifidobacteria investigated with an exposure longer than 2 hours and pH values < 5.0. Addition of thiocyanate also increased the susceptibility of the tested strains. In this in vitro study, the most resistant strains at all conditions were B. animalis subsp. lactis Ra 18 and P32 and B. choerinum Su 877, Su 837 and Su 891

Green manure and compost effects on n-p dynamics in mediterranean organic stockless systems

Stockless systems, where plant and animal production are uncoupled, represent a common condition in Mediterranean areas. In organic systems, soil fertility is mainly managed by green manures, whereas composts of plant origin represent suitable soil conditioners. The low P content of these materials, together with the shortage of animal waste availability, determine potential nutrient depletion overtime and, in calcareous soils, P mining conditions. In a two-year field experiment in Central Italy, the effect of green manure vetch (Vicia villosa) (GM+) was compared with a control left fallow (GM-), combined with P-based fertilizers (F) on organic maize (Zea mays). Yields and N-P dynamics were evaluated by direct measurements, nutrient balance and efficiency index. N balance was higher than in GM+ GM- (+71.8 and -23.6 kg N ha-1, respectively). P enriched compost with RP (rock-phosphate) (EP), showed significant improvement in P use efficiency (meanly +34%) than other treatments (unfertilized control (RP), not P enriched compost (NEP)) and P equilibrium in the short run. On the other hand, P-fertilizers and maize residues soil incorporation determined P surplus in a long perspective (up to +10 kg P ha-1). Results emphasize the possibility of P reintegration in stockless organic systems without animal wastes

EFFECTS OF COVER CROP MANAGEMENT AND COMPOST APPLICATION ON SOIL FERTILITY OF ORGANIC MELON

A field experiment was carried out in Central Italy on growing melon (Cucumis melo L.) after barley (Hordeum vulgare L.). Three different systems of cover crop termination (green manure, roller crimper and fallow, as control) were combined with three doses of compost (0, 15 and 30 t ha-1 d.m.) in a strip plot design. The main objective of the research was to evaluate their effects on organic melon production and on short and long term soil nitrogen (N) fertility. Marketable yield and quality and soil N availability along the melon cycle were determined and a simplified N budget calculated. Green manure (GM) treatment showed the highest total and marketable yield, followed by fallow (FA), while roller crimper (RC) was characterized by a significant lower yield respect to the other two treatments (45% and 62% of the marketable yield of GM and FA, respectively). On the other side, long term soil N fertility of GM and FA were characterized by N deficit unless combined with compost application at the dose of 15 t ha-1 d.m

Organic vs conventional stockless arable systems: a multidisciplinary approach to soil quality evaluation

Soil quality in Mediterranean conventional and organic stockless arable systems was assessed by a multidisciplinary approach. At the end of the first cycle of a 5-year crop rotation (2002–2006) in the Mediterranean Arable Systems Comparison Trial (MASCOT) long-term experiment, the effects of organic and conventional management systems were evaluated by using soil chemical, biochemical and biological parameters. Chemical and biochemical parameters linked to soil C cycle, arbuscular mycorrhizal fungi (AMF) and microarthropod communities were analysed according to a comparative approach. Results suggested a higher soil carbon sequestration in the organic respect to the conventional system, as shown by the values of total organic C (9.5 and 7.8 g kg1, for organic and conventional system, respectively) and potentially mineralisable C (277 and 254 mg kg1, for organic and conventional system, respectively). AMF population, AMF root colonisation and diversity of microarthropod population were slightly influenced by management system. On the other hand, mites/collembolans ratio was higher in conventionally than in organically managed soil (2.67 and 1.30, respectively), indicating as organic managed soils were more disturbed than conventional ones, probably as the consequence of the more frequent soil tillage performed for mechanical weeds control. The overall results demonstrated that, even in the short-term, the implementation of organically managed stockless systems in Mediterranean areas determined significant changes of some attributes for soil quality evaluation

Longitudinal study of Salmonella infection in four Italian farrow-to finish swine herds

A longitudinal study of Salmonella enterica infection was carried out in 4 Italian farrow-to-finish swine herds. In each herd 5 litters were randomly selected and in each litter 6 piglets ear tagged. Thus, on each farm 30 pigs were included in the study. Individual blood samples were collected for serologic examination at weaning from all piglets and in the same day from all sows 1n the farrowing unit. Piglets were bled again at approximately 60, 90, 150, 210 and 270 days of life with the last blood sample collected at slaughtering. In one herd, in which the duration of productive cycle was about 12 months, the last blood samples was collected at 350 days of life. 5 pen pooled faecal samples were collected from each herd for bacteriological examination with the same time schedule of blood samples. At slaughtering mesenteric lymph nodes were collected from each ear tagged pig. Sera-prevalence (cutoff S/P ratio 0,25) in sows varied from 93,8% to 100%. In all herds sera-prevalence in piglets showed a similar profile with complete decline of maternal antibodies at day 60 and clear sera-conversion between day 90 and day 150. The peak of sera-prevalence was observed between day 210 and day 270. Sera-prevalence at slaughtering varied from 66% to 100%. Salmonella was isolated from faecal samples in 3 out of 4 herds. No Salmonella was isolated from mesenteric lymph nodes at slaughter in 2 herds. Culture prevalence from mesenteric lymph nodes in the other herds was respectively 3,3% and 30%. This longitudinal study provides original information about epidemiological dynamics of Salmonella enterica infection in Italian swine herds in consideration of the typical longer fattening cycles

Rainfall effect on grass and <i>Lotus glaber mill</i>. mineral composition from Magdalena district

Los excesos hídricos incrementan la absorción de Fe por el forraje y éste puede reducir la captación de Cu y Zn. En el partido de Magdalena en los años donde aumentó el régimen de lluvias se registraron mayores prevalencias de hipocuprosis bovina. El objetivo del presente trabajo es establecer los cambios provocados por el exceso hídrico del suelo sobre la composición mineral del forraje. En doce establecimientos del partido de Magdalena, entre marzo y diciembre de 1997, se tomaron 76 muestras pareadas de Lotus glaber Mill (= Lotus tenuis Waldst. et Kit. ex Wild.) y gramíneas durante períodos secos y húmedos. Las muestras se sometieron a digestión ácida y se determinó el contenido de Cu, Fe, Mn y Zn por espectrofotometría de absorción atómica y el de S por titulación con arsenazo III. Los datos se analizaron mediante test de T y análisis de varianza. El contenido de Fe aumentó significativamente durante los períodos húmedos: 579 vs 206 ppm en L. glaber y 858 vs 104 ppm en gramíneas. El L. glaber presentó mayores concentraciones de Cu y Zn que las gramíneas. El contenido de Cu aumentó significativamente en las gramíneas durante el período húmedo y en el L. glaber no se modificó. El Mn aumentó significativamente en el L. glaber durante el período húmedo.Water excess increases forage Fe absorption, and in turn, Fe can reduce both Cu and Zn uptake by roots. It is known that Cu deficiency prevalence in cattle is higher when annual rainfall in Magdalena district is heavier. Our objective is to assess the changes in forage mineral composition caused by water excess in soil. Seventy six samples of Lotus glaber Mill. (= Lotus tenuis Waldst. et Kit. ex Wild.) and accompanying grass were taken, during dry and wet periods, in 12 beef breeding farms from Magdalena district, from march through December 1997. Samples were acid digested, and Cu, Fe, Mn and Zn concentration was measured by atomic absorption, whereas S content was measured by Arsenaze III tritration. Data were analyzed by T test and variance (p < 0.05). Iron concentration increased during wet periods: 579 vs 206 ppm for L. glaber and 858 vs 104 for grass samples (p: <0.05). L. glaber samples had higher Cu and Zn contents than grass samples. Copper concentration increased in grass samples (p < 0.05). Manganese concentration increased in L. glaber samples during wet periods (p < 0.05).Facultad de Ciencias Veterinaria

Identification of immunogenic candidate for new serological tests for Brucella melitensis by a proteomic approach.

Background: The diagnosis of brucellosis by serological tests is based on antigen suspensions derived from smooth lipopolysaccharide extracts, which can give false-positive results linked to cross-reactivity with other Gram-negative microorganisms, especially Yersinia enterocolitica O:9 and Escherichia coli O157:H7. Objective: The objective of the present study was the characterization by proteomic analysis of specific immunogenic proteins not associated with smooth lipopolysaccharide to improve the diagnostic tests used in the ovine brucellosis eradication programs. Methods: The serum from a sheep positive to Brucella melitensis was treated to eliminate all antibodies against such lipopolysaccharides and highlight the reaction towards the immunoreactive proteins in western blotting. Results: The immunoreactive bands were identified by nLC-MS/MS, and through bioinformatics tools, it was possible to select 12 potential candidates as protein antigens specific for Brucella melitensis. Conclusion: The detection of new antigens not subjected to cross-reactivity with other Gram-negative microorganisms can offer additional tools for the serological diagnosis of such diseases