Effects of dietary fat saturation on fatty acid composition and gene transcription in different tissues of Iberian pigs

The effect of two diets, respectively enriched with SFA (S) and PUFA (P), on FA tissue composition and gene expression was studied in fattened Iberian pigs. The FA composition of adipose, muscular and liver tissues was affected by dietary treatment. S group showed higher MUFA and MUFA/SFA ratio and lower PUFA and n-6/n-3 ratio than P group in all analyzed tissues. In muscle and liver the extracted lipids were separated into neutral lipids and polar lipid fractions which showed significantly different responses to the dietary treatment, especially in liver where no significant effect of diet was observed in NL fraction. The expression of six candidate genes related to lipogenesis and FA oxidation was analyzed by qPCR. In liver, stearoyl CoA desaturase (SCD), acetyl CoA carboxylase alpha (ACACA) and malic enzyme 1 (ME1) genes showed higher expression in S group. SCD, ACACA, ME1, and fatty acid synthase (FASN) gene expression levels showed a wide variation across the tested tissues, with much higher expression levels observed in adipose tissue than other tissues. Tissue FA profile and gene expression results support the deposition of dietary FA, the lipogenic effect of dietary saturated fat in liver and the employment of saturated dietary fat for endogenous synthesis of MUFA in all the analyzed tissues.

Evolution of oxidative/nitrosative stress biomarkers during an open-field vaccination procedure in sheep: effect of melatonin

Melatonin has been shown to exert immunomodularory properties with broad application in veterinary medicine. In previous work we have described that subcutaneous coadministration of melatonin to seeps vaccinated against two stumps of A1 and C strains of Dichelobacter nodosus enhanced both the antibody titer and serum IgG levels to A1 and C strains of D. nodosus compared to vaccinated animals not treated with melatonin. Following a similar protocol here we have investigated the effect of a higher dose of melatonin (36mg/animal) in the improvement of the immune response and in the possible oxidative/nitrosative stress produced during the immunization protocol. Our results show that footrot vaccine application induced nitrosative but not oxidative stress at 42 days post-vaccination, which was neutralized by melatonin administration. On the other hand, melatonin improved the immune response with respect to our previous data increasing the time of permanence of antibodies in serum, opening new perspectives for melatonin as prophylactic drug.

The use of melatonin as a vaccine agent

Molecules with immunomodulatory properties determine the magnitude and quality of immune responses specific for the coadministered antigen. Melatonin is considered a biological-response modifier of the immune system with broad application in veterinary medicine. In seasonally-breeding animals, the indolamine is able to improve reproductive performance. With the purpose of expanding new advantageous roles for melatonin, we investigated the effect of subcutaneous slow-release melatonin implants in the humoral response after a vaccination. We reported here a new feature of melatonin as an adjuvant-like system towards Dichelobacter nodosus (A1 and C serotypes)--the bacterium which cause ovine footrot--the most important cause of lameness in sheep. Antibody titres determined by both agglutination and ELISA techniques were substantially higher and were sustained for a longer duration than non-implanted animals. Remarkably, the effect of melatonin was completely dependent on the presence of aluminium hydroxide. The finding that melatonin enhances a defined immune response in vivo opens new perspectives for the improvement of Th2-biased immune responses by alum adjuvants.

Effectiveness of different adjuvants in stimulating Dichelobacter nodosus antibody in sheep vaccinated against ovine footrot

This research consists of an evaluation of the effectiveness of different substances administered as adjuvants in the stimulation of humoral immune response induced by the vaccine composed of strains A1, A2 and C of Dichelobacter nodosus. To do this, a total of 120 Merino sheep were vaccinated and revaccinated. These sheep were selected from a farm located in the region of Extremadura (Spain), and they were divided into 12 groups of 10 animals each. An additional group with 10 sheep was used as control. The immune response (titre of antibodies) was determined by agglutination tests and ELISA. The most pronounced immune response was obtained by the use of Freund's incomplete adjuvant and aluminium hydroxide as adjuvants.

Aetiology of ovine footrot in the Portuguese region of Alto Alentejo

In this work, we found it appropriate to carry out a study directed towards isolating and identifying the entailed microorganisms which trigger off footrot in sheep, placing special emphasis on the serotipification of the different Dichelobacter nodosus species. With this goal in mind four flocks from the Portuguese region of 'Alto Alentejo' were selected, all of them had one common feature: their main health problem was ovine footrot. We also set out to determine the elastolitic capacity of isolated strict-anaerobic bacteria, in order to be able to clarify the direct involvement of these microorganisms in the outbreak of this infectious process.

Comparison of erythromycin and oxytetracycline for the treatment of ovine footrot

A microbiological study of 25 cases of ovine footrot was performed. Cultures belonging to Dichelobacter nodosus were isolated in 48% of the sampled animals. The sensitivity of the 99 strict anaerobic bacterial isolates to 5 antibiotics (penicillin G, amoxycillin, spiramycin, erythromycin and oxytetracycline) was studied. The percentage of resistant cultures was in all cases higher than 30%. The efficacy of erythromycin and oxytetracycline in the treatment of ovine footrot was studied. To conduct this test, an intramuscular injection was applied, of one antimicrobial or the other, at the beginning of the treatment. The tolerance of animals to the antimicrobials, the success rate of treatment and the severity of lameness were evaluated. The percentage of animals cured within 15 days was around 75%. In contrast, only 44% improvement was achieved in the lameness. No differences were found between the two antimicrobials in the above indices.