Changes in bacterial population of gastrointestinal tract of weaned pigs fed with different additives.

This study aimed to provide novel insights into the gastrointestinal microbial diversity from different gastrointestinal locations in weaning piglets using PCR-restriction fragment length polymorphism (PCR-RFLP). Additionally, the effect of different feed additives was analyzed. Thirty-two piglets were fed with four different diets: a control group and three enriched diets, with avilamycin, sodium butyrate, and a plant extract mixture. Digesta samples were collected from eight different gastrointestinal segments of each animal and the bacterial population was analysed by a PCR-RFLP technique that uses 16S rDNA gene sequences. Bacterial diversity was assessed by calculating the number of bands and the Shannon-Weaver index. Dendrograms were constructed to estimate the similarity of bacterial populations. A higher bacterial diversity was detected in large intestine compared to small intestine. Among diets, the most relevant microbial diversity differences were found between sodium butyrate and plant extract mixture. Proximal jejunum, ileum, and proximal colon were identified as those segments that could be representative of microbial diversity in pig gut. Results indicate that PCR-RFLP technique allowed detecting modifications on the gastrointestinal microbial ecology in pigs fed with different additives, such as increased biodiversity by sodium butyrate in feed.

Effect of marbofloxacin on Haemophilus parasuis nasal carriage.

Haemophilus parasuis is a colonizer of the upper respiratory tract and the causative agent of Glässer's disease in swine. This study focused on the nasal carriage of H. parasuis after treatment with marbofloxacin. Three marbofloxacin treatments (three doses of 2mg/kg body weight [bw] every 24h, two doses of 4 mg/kg bw every 48 h and 8 mg/kg bw in one single shot) were used and all of them reduce significantly (p<0.05) the nasal carriage of H. parasuis as compared to control animals. Moreover, H. parasuis was not detected in the nasal cavities of piglets after administering the highest dose. The effect of a dose of 8 mg marbofloxacin/kg bw in one shot was further studied in a farm with clinical cases of Glässer's disease using a longitudinal study. Statistically significant reduction of nasal carriage of H. parasuis was detected during the first week after treatment in comparison with the control group. However, a clear relationship between the minimum inhibitory concentration (MIC) of the different strains, their putative virulence or the treatment group (antibiotic or control) from which they were isolated was not detected. Finally, the effect induced by the antibiotic treatment on the bacterial strains seemed to be transitory, since diverse H. parasuis strains (with high and low marbofloxacin MICs) were observed 7 days after finishing the treatment.