Analysis of MC4R polymorphism in Italian Large White and Italian Duroc pigs: association with carcass traits.

The melanocortin-4 receptor (MC4R) gene codes for a G protein transmembrane receptor playing an important role in energy homeostasis control. In pig a single nucleotide polymorphism c.1426G>A has been identified and associated to average daily gain, feed intake and fatness traits but a lack of agreement on the effects of the gene on carcass traits in different breeds comes out from many studies. In the present study the c.1426G>A polymorphism is analysed in two Italian pig breeds, Large White and Duroc to study the association of the MC4R gene with some carcass traits. The results show that the c.1426G>A polymorphism affects daily gain, feed conversion ratio and ham weight in both breeds, lean cuts in the Italian Duroc and backfat thickness in the Italian Large White. The presence of MC4R mRNA transcript in different porcine tissues was analysed.

Feed supplemented with 3 different antibiotics improved food intake and decreased the activation of the humoral immune response in healthy weaned pigs but had differing effects on intestinal microbiota.

The aim of this study was to determine the effects of 3 antibiotics used for pulmonary pathologies added in the feed of weaned pigs on growth performance, commensal microbiota, and immune response. At weaning, a total of 72 pigs were randomly assigned by BW and litter to 1 of the following diets: control (typical weaning diet), control + 400 mg of tilmicosin/kg, control + 600 mg of amoxicillin/kg, and control + 300 mg of doxycycline/kg. Individually penned pigs were slaughtered after 3 wk (12 pigs/treatment) or 4 wk (6 pigs/treatment). During the fourth week, all pigs received the control diet to test the residual effect of the antimicrobial supplementation. The antibiotic supplementation increased growth and feed intake during the first week (P < 0.01) and over the first 3 wk combined (P < 0.05). Gain-to-feed ratio tended to improve during the first week (P = 0.076) by the antibiotics compared with the control. Among the antibiotic treatments, no difference was observed in ADG and feed intake, which were also unchanged by the diet in the fourth week. The fecal enterobacteria counts were increased by amoxicillin on d 14 and 21 (P < 0.05 and 0.01, respectively) and were decreased by tilmicosin (P < 0.001) compared with the control. Amoxicillin decreased lactic acid bacteria (P < 0.01) counts compared with the control. The antibiotic supplementation tended to decrease total bacteria variability in the jejunum (Shannon index, P = 0.091) compared with the control. The antibiotic treatment decreased the mean total serum IgM concentration (P = 0.016) after 3 wk and did not change the mucosal histomorphometry of the small intestine. For tilmicosin, the observed positive action on piglet performance and feed intake can originate by the decreased costs of immune activation determined by the action on intestinal microbiota. For amoxicillin and doxycycline, the observation on intestinal and fecal microbiota seems to be not sufficient to explain their growth-promoting effect.

Effect of high oral doses of nitrate on salivary recirculation of nitrates and nitrites and on bacterial diversity in the saliva of young pigs.

Ingested nitrate is absorbed in the small intestine, recirculated into the saliva and reduced to nitrite by oral bacteria. In pigs receiving a moderate dietary addition of nitrate, the recirculation into the saliva is modest, so we aimed to assess the effect of higher nitrate doses to find out how the animal reacts to this new situation and to evaluate if a higher nitrate level could enhance the nitrate reduction process, improving the nitrite production Trial 1. Six piglets received 100 g of a commercial diet with 2.45% KNO(3) . In relation to baseline values, nitrate in blood serum and saliva increased 15 times, and declined after 6 h vs. 2 h. Salivary nitrite increased seven times after the addition and declined after 6 h vs. 2 h. Trial 2. Six piglets were fed a diet with or without 1.22% KNO(3) for 2 weeks. Salivary nitrate and nitrite increased with the addition of KNO3: nitrate increased from d0 to the end of the trial, nitrite increased 15 times after 1 week, but decreased after 2 weeks to 4.5-fold the control. After 2 weeks, nitrate reduced Shan diversity index of salivary microbiota. The present results indicate that the long exposure to high quantities of nitrates impairs the oral reduction of nitrate to nitrite and engenders a reduction of the mouth's microbiota diversity.