This study investigated intestinal oxidative damage caused by F18⁺ Escherichia coli and its amelioration with antibacterial bacitracin fed to nursery pigs. Thirty-six weaned pigs (6.31 ± 0.08 kg BW) were allotted in a randomized complete block design. Treatments were: NC, not challenged/not treated; PC, challenged (F18⁺ E. coli at 5.2 × 10⁹ CFU)/not treated; AGP challenged (F18⁺ E. coli at 5.2 × 10⁹ CFU)/treated with bacitracin (30 g/t). Overall, PC reduced (p < 0.05) average daily gain (ADG), gain to feed ratio (G:F), villus height, and villus height to crypt depth ratio (VH:CD), whereas AGP increased (p < 0.05) ADG, and G:F. PC increased (p < 0.05) fecal score, F18⁺ E. coli in feces, and protein carbonyl in jejunal mucosa. AGP reduced (p < 0.05) fecal score and F18⁺ E. coli in jejunal mucosa. PC reduced (p < 0.05) Prevotella stercorea populations in jejunal mucosa, whereas AGP increased (p < 0.05) Phascolarctobacterium succinatutens and reduced (p < 0.05) Mitsuokella jalaludinii populations in feces. Collectively, F18⁺ E. coli challenge increased fecal score and disrupted the microbiota composition, harming intestinal health by increasing oxidative stress, and damaging the intestinal epithelium, ultimately impairing growth performance. Dietary bacitracin reduced reduced F18⁺ E. coli populations and the oxidative damages they cause, thereby improving intestinal health and the growth performance of nursery pigs.

Muscle growth and repair rely on two main mechanisms – myonuclear accretion and subsequent protein accumulation. Altering the ability of muscle resident stem cells (satellite cells) to progress through their myogenic lineage can have a profound effect on lifetime muscle growth and repair. The use of the histone deacetylase (HDAC) inhibitor, butyrate, has had positive outcomes on the in vitro promotion of satellite cell myogenesis. In animal models, the use of butyrate has had promising results in treating myopathic conditions as well as improving growth efficiency, but the impact of dietary butyrate on satellite cells and muscle growth has not been elucidated. We investigated the impact of tributyrin, a butyrate prodrug, on satellite cell activity and muscle growth in a piglet model. Satellite cells from tributyrin‐treated piglets had altered myogenic potential, and piglets receiving tributyrin had a ~40% increase in DNA:protein ratio after 21 days, indicating the potential for enhanced muscle growth. To assess muscle growth potential, piglets were supplemented tributyrin (0.5%) during either the neonatal phase (d1–d21) and/or the nursery phase (d21–d58) in a 2 × 2 factorial design. Piglets who received tributyrin during the neonatal phase had improved growth performance at the end of the study and had a ~10% larger loin eye area and muscle fiber cross‐sectional area. Tributyrin treatment in the nursery phase alone did not have a significant effect on muscle growth or feed efficiency. These findings suggest that tributyrin is a potent promoter of muscle growth via altered satellite cell myogenesis.

Background: Dietary calcium and phosphorus are required for bone and muscle development. Deficiencies of these macrominerals reduce bone mineral and muscle accretion potentially via alterations of mesenchymal stem cell (MSC) and satellite cell (SC) activities. Objectives: With increasing interest in the role of early-life events on lifetime health outcomes, we aimed to elucidate the impact of dietary calcium and phosphorus, from deficiency through excess, on MSC and SC characteristics during neonatal development. Methods: Neonatal pigs [30 females, 1-d-old, 1.46 +/- 0.04 kg body weight (BW)] were fed milk replacers for 16 d that were isonitrogenous and isocaloric with a consistent ratio of calcium to phosphorus, but either 25% deficient (calcium: 0.78%; phosphorus: 0.60%; CaPD), adequate (calcium: 1.08%; phosphorus: 0.84%; CaPA), or 25% in excess (calcium: 1.38%; phosphorus: 1.08%; CaPE) of calcium and phosphorus requirements based on sow-milk composition and extrapolation from NRC requirements for older pigs. BW and feed intake were recorded daily. Blood was collected for serum phosphorus, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF23) determination. Humeri were collected for MSC isolation and radii/ulnae bone were collected for analysis. Longissimus dorsi muscle was collected for SC isolation and analysis. Results: Therewas 4.6% increase in bone ash percentage in CaPE-versus CaPD-fed pigs (P < 0.05). In vivo proliferation indicated a 41.3% increase in MSCs in CaPA compared with CaPD and a 19% increase in SCs in CaPA compared with both CaPE and CaPD. MSCs from CaPD had 2- to 5-fold greater expression of peroxisome proliferator-activated receptor. (PPAR.), fatty acid-binding protein 4 (FABP4), and lipoprotein lipase (LPL) but lower osteocalcin (BGLAP) and fibronectin (FN1) expression than CaPA (P < 0.05). SCs from CaPD-fed pigs had 19% lower in vivo proliferation than in CaPA-fed pigs. Conclusions: These findings demonstrated that feeding a diet marginally deficient in calcium and phosphorus to neonatal pigs had a great impact on bone development, MSC, and SC characteristics. These dietary deficiencies may program future bone health and muscle development by altering MSC and SC activities.

Satellite cells (SC) are a population of muscle resident stem cells that are responsible for postnatal muscle growth and repair. With investigation into the genomic regulation of SC fate, the role of the epigenome in governing SC myogenesis is becoming clearer. Histone deacetylase (HDAC) inhibitors have been demonstrated to be effective at enhancing the myogenic program of SC, but their role in altering the epigenetic landscape of SC remains undetermined. Our objective was to determine how an HDAC inhibitor, butyrate, promotes myogenic differentiation. SC from tributyrin treated neonatal piglets showed a decrease relative to SC from control animals in the expression of enhance of zeste homologue-2 (EZH2), a chromatin modifier, ex vivo. Chromatin Immunoprecipitation-Sequencing (ChIP-Seq) analysis of SC isolated from tributyrin treated pigs showed a global reduction of the tri-methylation of lysine 27 of histone H3 (H3K27me3) repressive chromatin mark. To determine if reductions in EZH2 was the primary mechanism through which butyrate affects SC behavior, SC were transfected with siRNA targeting EZH2, treated with 0.5 mM butyrate, or both. Treatment with butyrate reduced paired-box-7 (Pax7) and myogenic differentiation-1 (MyoD) gene expression, while siRNA caused reductions in EZH2 had no effect on their expression. EZH2 depletion did result in an increase in differentiating SC, but not in myotube hypertrophy. These results indicate that while EZH2 reduction may force myogenic differentiation, butyrate may operate through a parallel mechanism to enhance the myogenic program.

Although concerns over the environmental impact of excess P in the excreta from pig production and governmental regulations have driven research toward reducing dietary supplementation of P to swine diets for over a decade, recent dramatic increases in feed costs have further motivated researchers to identify means to further reduce dietary P supplementation. We have demonstrated that genetic background impacts P utilization in young pigs and have identified genetic polymorphisms in several target genes related to mineral utilization. In this study, we examined the impact of a SNP in the calcitonin receptor gene (CALCR) on P utilization in growing pigs. In Exp. 1, 36 gilts representing the 3 genotypes identified by this CALCR SNP (11, 12, and 22) were fed a P-adequate (PA) or a marginally P-deficient (approximately 20% less available P; PD) diet for 14 wk. As expected, P deficiency reduced plasma P concentration, bone strength, and mineral content (P < 0.05). However, the dietary P deficiency was mild enough to not affect the growth performance of these pigs. A genotype × dietary P interaction (P < 0.05) was observed in measures of bone integrity and mineral content, with the greatest reduction in bone strength and mineral content due to dietary P deficiency being associated with the allele 1. In Exp. 2, 168 pigs from a control line and low residual feed intake (RFI) line were genotyped for the CALCR SNP and fed a PA diet. As expected, pigs from the low RFI line consumed less feed but also gained less BW when compared with the control line (P < 0.05). Although ADFI did not differ between genotypes, pigs having the 11 genotype gained less BW (P < 0.05) than pigs having the 12 or 22 genotypes. Pigs of the 11 and 12 genotypes had bones that tolerated greater load when compared with animals having the 22 genotype (P < 0.05). A similar trend was observed in bone modulus and ash % (P < 0.10). These data are supportive of the association of this CALCR SNP with bone integrity and its response to dietary P restriction. Although the allele 1 is associated with greater bone integrity and mineral content during adequate P nutrition, it is also associated with the greatest loss in bone integrity and mineral content in response to dietary P restriction. Understanding the underlying genetic mechanisms that regulate P utilization may lead to novel strategies to produce more environmentally friendly pigs.

This study investigated the intestinal oxidative damages caused by F18⁺Escherichia coli and its amelioration with an antibacterial bacitracin fed to nursery pigs. Thirty-six weaned pigs (6.31 ± 0.08 kg BW) were allotted in RCBD. Treatments were: NC, not challenged/not treated; PC, challenged (F18⁺E. coli at 5.2 × 10⁹ CFU)/not treated; AGP, challenged (F18⁺E. coli at 5.2 × 10⁹ CFU)/treated with bacitracin (30 g/t). The F18⁺E. coli was orally inoculated to pigs on challenged treatments at d 7. The unchallenged pigs received an oral dose of sterile saline solution. The fecal score was recorded daily. Body weight and feed intake were recorded weekly. On d 14 and 28, fecal and blood samples were collected. On d 28, all pigs were euthanized to collect intestinal samples. F18⁺E. coli counting, microbiota composition, and intestinal health variables were analyzed. Data were analyzed using the mixed procedure on SAS 9.4. Overall, PC reduced (P < 0.05) ADG (353 to 282 g), G:F (0.71 to 0.55), villus height (527 to 394 µm), and VH:CD (2.22 to 1.58), whereas AGP increased (P < 0.05) ADG (298 to 344 g), and G:F (0.55 to 0.61). PC increased (P < 0.05) fecal score from d 7 to 14 (3.0 to 4.6), from 14 to 21 (2.8 to 3.9), and from d 21 to 28 (2.5 to 3.2); increased F18⁺E. coli (5.9 to 7.5 log DNA) in feces at d 14, and protein carbonyl (2.15 to 3.61 nmol/mg protein) in jejunal mucosa. AGP reduced (P < 0.05) fecal score from d 7 to 14 (4.6 to 4.0) and from d 14 to 21 (3.9 to 3.4) and reduced F18⁺E. coli (4.3 to 3.9 log DNA) in jejunal mucosa. PC reduced (P < 0.05) Prevotella stercorea (5.1 to 1.5%) population in jejunal mucosa, whereas AGP increased (P < 0.05) Phascolarctobacterium succinatutens (3.0 to 10.0%) and reduced (P < 0.05) Mitsuokella jalaludinii (8.7 to 2.0%) populations in feces. Collectively, F18⁺E. coli challenge increased fecal score and disrupted the microbiota composition, harming intestinal health by increasing oxidative stress and damaging the intestinal epithelium, ultimately impairing growth performance. Dietary bacitracin reduced oxidative damages caused by F18+ E. coli thereby protecting intestinal health by reducing F18⁺E. coli population in jejunal mucosa and fecal score, consequently improving the growth performance of nursery pigs.