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Proliferative enteropathy (PE) is characterized by diarrhea and reduced weight gains in growing pigs and intestinal hemorrhage in finishers. Vaccination, antibiotic medication, and improved hygiene can control PE, but their efficacy depends upon the epidemiology of PE. This study monitored the timing and severity of PE in 84 commercial pens across seven treatments, including disinfection, vaccination, no treatment, medication with olaquindox (50, 25 and 12.5 ppm), and combined disinfection and vaccination. Vaccination with or without lime disinfection suppressed clinical signs of PE and reduced the number of excreted L. intracellularis relative to untreated pigs housed in cleaned or cleaned and disinfected pens between 9 and 17 weeks of age. Continuous olaquindox mediation to 17 weeks of age prevented L. intracellularis infection, leaving finisher pigs naïve. These finisher pigs suffered an outbreak of hemorrhagic enteropathy with significant reductions in weight gain, feed intake, and mortalities of 4.6%. Over the 13 week grow/finish period, vaccinated pigs housed in disinfected pens showed significantly higher weight gain and feed intake relative to all other treatments, equating to a weight gain difference of between 3.6 and 3.9 kg per pig. Monitoring the immune response and fecal excretion of L. intracellularis in pens of pigs enabled effective PE control strategies to be evaluated on the farm.

The aim of this study was to investigate the effects of sex and dietary lecithin on growth performance, meat quality, muscle collagen content and gene expression of key genes involved in collagen synthesis in finisher pigs. A total of 256 pigs (Large White × Landrace) were allotted to a 2 × 2 factorial arrangement involving sex (gilt or immunocastrated [IC] male) and dietary treatment (0 or 5 g/kg of dietary lecithin). All diets were formulated to contain 4.6% tallow with relatively high total fat of 6.3%. After 5 weeks of dietary treatment, pigs were slaughtered and Longissimus dorsi muscle was obtained for evaluation of meat quality and collagen content. Rectus abdominis muscle was analysed for gene expression of key genes involved in collagen synthesis namely, type I (α1) procollagen (COL1A1), type III (α1) procollagen (COL3A1), α-subunit of prolyl 4-hydroxylase (P4H), lysyl oxidase and metalloproteinase-1 (MMP-1). The results showed that lecithin improved feed efficiency of all pigs (P 0.05). Lecithin also had no effect on meat compression, shear force, collagen content and gene expression (P > 0.05). Immunocastrated male had higher growth rate and increased COL1A1 expression than gilts. However, sex had no effect on fat depth at the P2 site (65 mm from the midline over the last rib), collagen content and expression of other genes (P > 0.05). In conclusion, lecithin improved feed efficiency in finishing pigs without impacting pork quality. Thus, inclusion of lecithin in diets containing high amount of tallow during the summer period could be beneficial. Keywords: Fat, Feed efficiency, Lecithin, Meat quality, Pigs

The purpose of this study was to investigate the effect of dietary lecithin on skeletal muscle gene expression of collagen precursors and enzymes involved in collagen synthesis and degradation. Finisher gilts with an average start weight of 55.9 ± 2.22 kg were fed diets containing either 0, 4, 20 or 80 g/kg soybean lecithin prior to harvest for six weeks and the rectus abdominis muscle gene expression profile was analyzed by quantitative real-time PCR. Lecithin treatment down-regulated Type I (α1) procollagen (COL1A1) and Type III (α1) procollagen (COL3A1) mRNA expression ( p < 0.05, respectively), indicating a decrease in the precursors for collagen synthesis. The α-subunit of prolyl 4-hydroxylase (P4H) mRNA expression also tended to be down-regulated ( p = 0.056), indicating a decrease in collagen synthesis. Decreased matrix metalloproteinase-1 (MMP-1) mRNA expression may reflect a positive regulatory response to the reduced collagen synthesis in muscle from the pigs fed lecithin ( p = 0.035). Lecithin had no effect on tissue inhibitor metalloproteinase-1 (TIMP-1), matrix metalloproteinase-13 (MMP-13) and lysyl oxidase mRNA expression. In conclusion, lecithin down-regulated COL1A1 and COL3A1 as well as tended to down-regulate α-subunit P4H expression. However, determination of muscle collagen content and solubility are required to support the gene functions.