Swine Growth Research Articles

Friend or Foe? Impacts of Dietary Xylans, Xylooligosaccharides, and Xylanases on Intestinal Health and Growth Performance of Monogastric Animals.

Simple SummaryXylan is naturally present in typical feedstuffs fed to animals and has been shown to cause increased digesta viscosity reducing nutrient digestibility and growth. Xylooligosaccharides are sugar oligomers consisting of xylose units that can be extracted and purified from biomaterials for use as a prebiotic in monogastric feeds. Xylooligosaccharides can also be obtained from the hydrolysis of xylan either in the intestine of the animal or in-vitro through various techniques. The question of xylanase supplementation versus xylooligosaccharide supplementation as well as symbiosis of both on the intestinal health and performance of monogastric livestock is still up for debate. Xylanase inhibitors present in common cereal grains provide yet another obstacle to overcome and are found to be highly variable. As the fear of antibiotic resistance increases, novel approaches to improve growth performance and enhance intestinal health without the use of antibiotics also increase. The aim of this article is to review the structural difference and its impact on xylan in feeds, classification and the use of various xylanases, as well as the production and use of xylooligosaccharides for the physiological effects on intestinal health and growth performance of monogastric animals.This paper discusses the structural difference and role of xylan, procedures involved in the production of xylooligosaccharides (XOS), and their implementation into animal feeds. Xylan is non-starch polysaccharides that share a β-(1-4)-linked xylopyranose backbone as a common feature. Due to the myriad of residues that can be substituted on the polymers within the xylan family, more anti-nutritional factors are associated with certain types of xylan than others. XOS are sugar oligomers extracted from xylan-containing lignocellulosic materials, such as crop residues, wood, and herbaceous biomass, that possess prebiotic effects. XOS can also be produced in the intestine of monogastric animals to some extent when exogenous enzymes, such as xylanase, are added to the feed. Xylanase supplementation is a common practice within both swine and poultry production to reduce intestinal viscosity and improve digestive utilization of nutrients. The efficacy of xylanase supplementation varies widely due a number of factors, one of which being the presence of xylanase inhibitors present in common feedstuffs. The use of prebiotics in animal feeding is gaining popularity as producers look to accelerate growth rate, enhance intestinal health, and improve other production parameters in an attempt to provide a safe and sustainable food product. Available research on the impact of xylan, XOS, as well as xylanase on the growth and health of swine and poultry, is also summarized. The response to xylanase supplementation in swine and poultry feeds is highly variable and whether the benefits are a result of nutrient release from NSP, reduction in digesta viscosity, production of short chain xylooligosaccharides or a combination of these is still in question. XOS supplementation seems to benefit both swine and poultry at various stages of production, as well as varying levels of XOS purity and degree of polymerization; however, further research is needed to elucidate the ideal dosage, purity, and degree of polymerization needed to confer benefits on intestinal health and performance in each respective species.

246 Maternal Programming of the Piglet Microbiome from Birth to Weaning

Abstract The objective of this study was to investigate seeding of the piglet microbiome, in the context of maternal programming in pre/perinatal environments. Maternal programming refers to maternal factors that predetermine offspring development and health. We hypothesized that increased sanitation level in maternal environments affects development of piglet fecal and nasal microbiomes, and physiological performance. Six sows were allocated randomly to two treatment groups: farrowing stalls cleaned with (D; n = 3) or without (ND; n = 3) disinfectant. Swabs were collected from stall floors, drinkers and feeders, and from sows’ vaginal, rectal, oral and udder surfaces at d109 of gestation and the day before farrowing. Fecal and nasal swabs were collected from piglets at days: 0 (within 24h of birth), 7, 14, and 21 postpartum. Nine piglets were selected randomly from each sow (n = 27/treatment) for microbiome analyses. DNA was extracted from swabs and the V4 variable region of the 16srRNA bacterial gene was sequenced on the MiSeq platform. Sequence data were analyzed using DADA2 and various packages within the R statistical software. Although environmental microbiomes were different between D and ND stalls (PERMANOVA, R2 = 0.474, P = 0.031) after cleaning, no compositional differences were detected among any D or ND sow samples. However, at d0, ND compared with D piglets exhibited higher gut (Shannon’s H, P = 9.131e-08) and nasal (P = 6.164e-08) alpha diversity. ND piglets also displayed greater nasal bacterial diversity at d21 (P = 0.036), and different gut (R2 = 0.06–0.129, P = 0.001) and nasal (R2 = 0.136–0.196, P = 0.001) microbiome compositions across all timepoints. However, D piglets exhibited higher average birth (P = 3.773e-05) and weaning weights (P = 5.803e-06) compared to ND piglets. These results indicate that sanitation level during farrowing persistently alters swine microbiomes and growth performance.

Screening of Microbes Associated With Swine Growth and Fat Deposition Traits Across the Intestinal Tract.

Pigs, as one of the most common livestock species worldwide, are expected to have a fast growth rate and lower subcutaneous fatness but higher intramuscular fat (“marbling meat”). Nowadays, it is believed that not only host genetics but also its gut microbiomes can modulate farm animal phenotypes, however, many of the mechanisms remain elusive. We measured the body weight (BW), average daily gain (ADG), backfat thickness (BFT), and intramuscular fatness (IMF) of 91 Enshi pigs at 260 days of age, then genotyped each one individually using a 50K single nucleotide polymorphism array and performed 16S ribosomal RNA gene sequencing on 455 microbial samples from the jejunum, ileum, cecum, colon, and rectum. The microbial diversity showed notable spatial variation across the entire intestinal tract, with the cecum and colon having the highest α-diversity. The cecal and colonic microbiotas made greater contributions to BW and ADG and accounted for 22–37% of the phenotypic variance. The jejunal and cecal microbiotas contributed more (13–31%) to the BFT and IMF than the other segments. Finally, from cecum, colon, and jejunum, we identified eight microbial taxa that were significantly correlated with the target traits. The genera Alloprevotella and Ruminococcaceae UCG-005 were highly positively correlated with BW and ADG. The genera Prevotellaceae UCG-001 and Alistipes in the cecum and Clostridium sensu stricto 1 in the jejunum were highly positively correlated with BFT and IMF. The genera Stenotrophomonas, Sphaerochaeta, and Desulfovibrio were negatively associated with the mentioned traits. These findings could aid in developing strategies for manipulating the gut microbiota to alter production performance in pigs.

A standardized model to study effects of varying 24-h colostrum dose on postnatal growth and development.

Survival, feed efficiency, growth, and fertility of swine are dependent on colostrum intake in the first 24 h after birth. This study determined the effects of three doses of a homogeneous colostrum sample on 24-h body weight, rectal temperature (RT), immunocrit, and growth and survival to postnatal day (PND) 7. Three female piglets were selected from eight litters (n = 24 piglets) at birth, removed from their litter, and bottle-fed 10% (COL10, n = 8), 15% (COL15, n = 8), or 20% (COL20, n = 8) colostrum based on birth weight over 12 bottle feedings every 2 h. At 24 h, piglets were weighed, RT recorded, and blood was collected to measure immunocrit. Piglets were returned to the litter of origin, and weight was measured daily until PND 7. Colostrum dose had an overall effect on weight gain at 24 h, RT, immunocrit, and growth to PND 7 (P < 0.05). Piglets in the 20% BrW colostrum group had greater weight gain, RT, and immunocrit at 24 h than COL10 piglets (P < 0.05), but these variables were not different between COL15 and the other treatments. Despite no difference in average daily gain after being returned to their litters, the greater weight (P < 0.05) in COL20 compared to COL10 and COL15 was sustained over 7 d. Seven piglets in each treatment survived to PND 7. This model using standardized doses of a homogeneous colostrum sample enables controlled studies aimed at understanding the role of 24-h colostrum intake on piglet development.

Replacing dietary antibiotics with 0.20% l-glutamine and synbiotics following weaning and transport in pigs.

Dietary antibiotic use has been limited in swine production due to concerns regarding antibiotic resistance. However, this may negatively impact the health, productivity, and welfare of pigs. Therefore, the study objective was to determine if combining dietary synbiotics and 0.20% l-glutamine would improve pig growth performance and intestinal health following weaning and transport when compared with traditionally used dietary antibiotics. Because previous research indicates that l-glutamine improves swine growth performance and synbiotics reduce enterogenic bacteria, it was hypothesized that supplementing diets with 0.20% l-glutamine (GLN) and synbiotics (SYN; 3 strains of Lactobacillus [1.2 × 10^9 cfu/g of strain/pig/d] + β-glucan [0.01 g/pig/d] + fructooligosaccharide [0.01 g/pig/d]) would have an additive effect and improve pig performance and intestinal health over that of dietary antibiotics. Mixed-sex pigs (N = 226; 5.86 ± 0.11 kg body weight [BW]) were weaned (19.4 ± 0.2 d of age) and transported for 12 h in central Indiana. Pigs were blocked by BW and allotted to one of two dietary treatments (5 to 6 pigs per pen): antibiotics (positive control [PC]; chlortetracycline [441 ppm] + tiamulin [38.5 ppm]), no antibiotics (negative control [NC]), GLN, SYN, or the NC diet with both the GLN and SYN additives (GLN + SYN) fed for 14 d. From day 14 post-weaning to the end of the grow-finish period, all pigs were provided common antibiotic-free diets. Data were analyzed using PROC GLIMMIX and PROC MIXED in SAS 9.4. Overall, haptoglobin was greater (P = 0.03; 216%) in NC pigs compared with PC pigs. On day 13, GLN and PC pigs tended to have reduced (P = 0.07; 75.2% and 67.3%, respectively) haptoglobin compared with NC pigs. On day 34, the jejunal goblet cell count per villi and per millimeter tended to be greater (P < 0.08; 71.4% and 62.9%, respectively) in SYN pigs compared with all other dietary treatments. Overall, jejunal mucosa tumor necrosis factor-alpha (TNFα) gene expression tended to be greater (P = 0.09; 40.0%) in NC pigs compared with PC pigs on day 34. On day 34, jejunal mucosa TNFα gene expression tended to be greater (P = 0.09; 33.3%, 41.2%, and 60.0%, respectively) in GLN pigs compared with SYN, GLN + SYN, and PC pigs. Although it was determined that some metrics of pig health were improved by the addition of GLN and SYN (i.e., haptoglobin and goblet cell count), overall, there were very few differences detected between dietary treatments and this may be related to the stress load incurred by the pigs.

The presence of tetracyclines and sulfonamides in swine feeds and feces: dependence on the antibiotic type and swine growth stages.

Swine farms are one of the important sources of antibiotics in the environment. In this study, 42 samples of compound feed and feces of swine collected at different growth stages from intensive farms were evaluated for the occurrence and concentrations of three tetracyclines (TCs, namely oxytetracycline, chlortetracycline, and doxycycline) and three sulfonamides (SAs, namely sulfadiazine, sulfadimidine, and sulfamethoxazole). To check for other additional sources of antibiotic administration, ratios (R) of the measured and the predicted levels of each antibiotic excreted via feces were also estimated. Our results showed that the maximum concentration of TCs was 376,210μgkg-1 and 541,020μgkg-1 in the feeds and feces, respectively, both for oxytetracycline. In contrast, the highest concentration of SAs were 16.98μgkg-1 for sulfadimidine in the feeds and 14.70μgkg-1 for sulfadiazine in the feces. The concentrations of ΣTCs (sum of the three tetracyclines) in swine feeds and feces were found to be 1-4 orders of magnitude higher than those of ΣSAs (sum of the three sulfonamides). Approximately 36% of the R values were found to be greater than one, indicating other sources of administration such as injection and/or oral administration (via drinking water) may also contribute to the presence of antibiotics in feces. Most of the higher R values were found in starter pigs, which were generally administrated with antibiotics by multiple routes to prevent disease and promote swine growth. Our study suggests that comprehensive measures may be undertaken to control antibiotic use in intensive swine farms.

Heritability and genome-wide association of swine gut microbiome features with growth and fatness parameters

Despite recent efforts to characterize longitudinal variation in the swine gut microbiome, the extent to which a host’s genome impacts the composition of its gut microbiome is not yet well understood in pigs. The objectives of this study were: i) to identify pig gut microbiome features associated with growth and fatness, ii) to estimate the heritability of those features, and, iii) to conduct a genome-wide association study exploring the relationship between those features and single nucleotide polymorphisms (SNP) in the pig genome. A total of 1,028 pigs were characterized. Animals were genotyped with the Illumina PorcineSNP60 Beadchip. Microbiome samples from fecal swabs were obtained at weaning (Wean), at mid-test during the growth trial (MidTest), and at the end of the growth trial (OffTest). Average daily gain was calculated from birth to week 14 of the growth trial, from weaning to week 14, from week 14 to week 22, and from week 14 to harvest. Backfat and loin depth were also measured at weeks 14 and 22. Heritability estimates (±SE) of Operational Taxonomic Units ranged from 0.025 (±0.0002) to 0.139 (±0.003), from 0.029 (±0.003) to 0.289 (±0.004), and from 0.025 (±0.003) to 0.545 (±0.034) at Wean, MidTest, and OffTest, respectively. Several SNP were significantly associated with taxa at the three time points. These SNP were located in genomic regions containing a total of 68 genes. This study provides new evidence linking gut microbiome composition with growth and carcass traits in swine, while also identifying putative host genetic markers associated with significant differences in the abundance of several prevalent microbiome features.

Application of meta‐analysis towards understanding the effect of adding a methionine hydroxy analogue in the diet on growth performance and feed utilization of fish and shrimp

AbstractMethionine hydroxy analogue (MHA) has been widely used and shows positive effects on growth in poultry, swine, ruminant and aquatic animals. Nevertheless, the utilization efficiency of methionine hydroxy analogue remains controversial considering the wide variation in effects across studies, feeding parameters and environmental culture conditions. Meta‐analysis can quantify the effect of adding MHA on animal performance. Here, we analysed the effect of MHA‐supplemented diets on the final weight (FW), per cent weight gain (WG), protein efficiency ratio (PER), feed conversion ratio (FCR) and feed efficiency (FE) in common, diverse aquaculture taxa. To conduct the meta‐analyses, twenty‐three published studies were included that accounted for 249 effect sizes estimated across eight fish and one shrimp species. The effect size (measured as the standardized mean difference; Hedges’ g) of response parameters between MHA level in a diet formulation and an MHA‐less control condition was calculated. Based on these results, adding MHA in the diet can significantly improve FW, WG, PER, and FE and decrease FCR for fish rather than shrimp. Using meta‐regression analysis, there was a significant quadratic linear relationship between MHA addition and effect size for FW (P = 0.002 for MHA, P = 0.042 for MHA2), and significant linear relationships between MHA addition and effect size for WG (P = 0.0005) and FCR (P = 0.002). There was no significant relationship, linear or non‐linear, between the MHA addition and effect size for FE (P = 0.985) and PER (P = 0.461). In all, when properly dosed in diets, MHA can significantly improve aquaculture production for fish.

Effect of a dual enteric and respiratory pathogen challenge on swine growth, efficiency, carcass composition, and pork quality1.

The objective of this study was to determine the influence of a dual respiratory and enteric pathogen challenge on growth performance, carcass composition, and pork quality of high and low feed efficient pigs. Pigs divergently selected for low and high residual feed intake (RFI, ~68 kg) from the 11th generation of Iowa State University RFI project were used to represent high and low feed efficiency. To elicit a dual pathogen challenge, half of the pigs (n = 12/line) were inoculated with Mycoplasma hyopneumoniae (Mh) and Lawsonia intracellularis (MhLI) on days post-inoculation (dpi) 0. Pigs in a separate room of the barn were not inoculated and used as controls (n = 12/RFI line). Pigs were weighed and feed intake was recorded to calculate ADG, ADFI, and G:F for the acclimation period (period 1: dpi -21 to 0), during peak infection (period 2: dpi 0 to 42), and during the remaining growth period to reach market weight (period 3: dpi 42 to harvest). At ~125 kg, pigs were harvested using standard commercial procedures. Carcasses were evaluated for composition (weight, fat free lean, loin eye area, 10th rib fat depth) and meat quality (pH decline, temperature decline, Hunter L, a, and b, subjective color and marbling, star probe, drip loss, cook loss, proximate composition, and desmin degradation). Challenged pigs had lesser ADFI than controls during period 2 (P < 0.05), but had greater ADG and G:F during period 3 (P < 0.05). Selection for feed efficiency did not result in a differential response to MhLI (P > 0.05). Loin chops from the less feed efficient, high RFI pigs, had greater drip loss, greater cook loss, lesser moisture content, greater Hunter L values, and greater Hunter b values (P < 0.05) than loin chops from low RFI pigs. Infection status did not significantly affect carcass composition or pork quality traits (P > 0.05). These results indicate that a MhLI challenge early in growth did not significantly affect ultimate carcass composition or meat quality traits. Selection for greater feed efficiency in pigs did not affect their response to pathogenic challenge.

The use of microarrays to define functionally-related genes that are differentially expressed in the cycling pig uterus

In swine and other livestock, the uterine endometrium exhibits dramatic morphological and secretory changes throughout the oestrous cycle and during pregnancy. Such physiological changes are a reflection of extremely complex interactions between gene products (RNA and protein). The recent development of genomics and proteomics methods, as well as associated bioinformatics tools, has provided the means to begin characterising such interactions. Indeed, the analysis of the transcriptome and proteome of cells and tissues now comprises a new field of study known as 'systems biology'. Currently, the most powerful technique available to the systems biologist is the microarray. These platforms represent oligonucleotide or cDNA fragments spotted in a specified high-density pattern on a solid support. Hybridisation of fluorescently-tagged cDNAs from different tissue sources permits the measurement of thousands of RNAs in parallel. The method permits the identification of genes that are present at different amounts between the two tissues and, more importantly, it permits the identification of groups of genes (clusters) that are expressed in comparable patterns. Results from a recent expression profiling experiment are described. The goal of the profiling experiment was to define genes that are differentially expressed in endometrium during the oestrous cycle. The experiment used an in-house cDNA microarray with >14,000 distinct cDNAs cloned from reproductive tissues. Total RNAs from cyclic endometrium (Days 0, 3, 6, 10, 12, 14 and 18 post-oestrus) were reverse transcribed into cDNAs, labelled with fluorescent dye and hybridised to the arrays along with cDNAs derived from a reference RNA pool. A total of 4,827 genes were found to differ significantly at some time during the oestrous cycle. Clustering methods were able to define numerous groups of similarly expressed genes. These data will help to define the complex patterns of endometrial genes acting in concert to create the environments required for fertilisation, embryo growth and conceptus development in swine.

Madin-Darby canine kidney cell sialic acid receptor modulation induced by culture medium conditions: Implications for the isolation of influenza A virus.

BackgroundThe influenza A virus (IAV) binds to α‐2,3‐ and α‐2,6‐linked sialic acid (SA) receptors expressed by Madin‐Darby canine kidney (MDCK) cells. The receptor distribution may therefore be important in regulating IAV propagation. Serum‐free medium (SFM) avoids variability in conventional culture medium containing fetal bovine serum (FBS), which can have variable composition and may contain endotoxins. However, little is known about the distribution of SA receptors on cells maintained in SFM.ObjectivesWe assessed the influence of culture media on MDCK cell SA receptor distribution along with the effect of SA receptor distribution on IAV recovery. We hypothesized that SFM would increase the proportion of α‐2,6‐linked SA receptors present and alter isolate recovery.MethodsMadin‐Darby canine kidney cells were cultured in medium containing FBS and two SFMs. Cell surface distribution of α‐2,6‐ and α‐2,3‐linked receptors was determined using flow cytometry. Recovery of swine‐ and avian‐lineage IAVs from MDCK cells maintained in each medium was quantified as TCID50.ResultsMadin‐Darby canine kidney cells cultured in UltraMDCK SFM expressed both SA receptors and supported the growth of both swine‐ and avian‐lineage IAVs. Cells maintained in other medium inconsistently expressed each receptor and the avian IAV grew to lower titers in cells cultured with FBS.ConclusionsMedium conditions altered the distribution of SA receptors present on MDCK cells and affected IAV recovery. Culture in UltraMDCK SFM resulted in cells expressing both receptors and IAVs grew to higher titers than in the other culture condition, indicating that this medium may be useful for culturing IAV from multiple species.

58 Feed, feeding levels, and tissue analytics of vitamins: Observations from the field

Abstract Targeted vitamin inclusion rates within swine diets are typically at levels 2–7 times that of the known published requirements. These increased rates are mainly looked at as an “insurance policy” since very little vitamin research has been conducted in the last two decades and swine growth rates and reproductive traits have increased substantially during this same time. When production issues such as broken bones, downer animals, or sudden deaths occur, vitamin analysis is commonly done on feed, serum, or tissue samples. This discussion will shed light on observations around vitamin analytics that include variation due concentration within product, lab-to-lab variation, and within lab variation. In addition to discrepancies found in feed, serum and liver sample vitamin analytics do not seem to present a clear picture. Across multiple phases of production, these analysis consistently fall well below what would be considered to be reference values that are reported by diagnostic labs. This occurs not only in sick animals but also in animals that appear to be in perfect health and are consuming adequate levels of feed. In order to determine the impact of vitamin supplementation on performance and serum/tissue vitamin status, five trials across sows, nursery, and grow-finish swine were conducted. The goal of these trials is not to determine the various vitamin requirements, but to begin the conversation in order to help establish new reference values that are applicable to today’s genetics, vitamin supplementation levels, and rearing environments. Hopefully this presentation will lead to further questions and discussions within the industry regarding level of vitamin supplementation and the subsequent impacts on performance and serum/tissue vitamin status.

83 Lifelong dynamics of the swine gut microbiome: from birth to market

Abstract Despite the recent advances in the swine gut microbiomes during different growth stages, a comprehensive longitudinal study of the lifelong dynamics of the swine gut microbiome is lacking. To fill this gap of knowledge, we selected seventeen piglets (PIC29*380) that were born on the same date from three sows. We collected a total of 274 rectal swabs during lactation (d 0, 11, 20), nursery (d 27, 33, 41, 50, 61), growing (d 76, 90, 104, 116), and finishing (d 130, 146, 159, and 174) stages. Samples were extracted using the Powersoil DNA isolation kit (Qiagen, Hilden, Germany) and sequenced with an Illumina Miseq sequencer targeting the V4 region of the 16 S rRNA gene. Sequences were analyzed with the Deblur algorithm in the QIIME2 package. In general, alpha diversity including community richness (e.g., number of observed features, Chao1) and diversity (e.g., Shannon Index) showed an overall trend of increasing from lactation to the finishing stage (P &lt; 0.01). Gradual and significant changes in community structures were also observed along the four growth stages (ANOSIM, R = 0.66; P &lt; 0.01). Non-parametric permutational multivariate analysis of variance shows that main factors driving the lifelong community dynamics included age and diet. Seventeen phylum members were discovered in the lifelong pig gut microbiome with Firmicutes and Bacteroidetes being the most abundant phyla. LEfSe analysis revealed 63 bacterial features that are stage specific. By using a regressing tree based Random Forest model we identified five bacterial features that are associated with swine growth performance including features 26 (Turicibacteraceae Turicibacter), 27 (Clostridium butyricum), 18 (Clostridiaceae), 19 (Clostridium perfringens) and 4 (Clostridiaceae). Characterization of the lifelong dynamics of 17 healthy pigs from birth to market provides a foundation for gut microbiome studies focusing on swine development, health and growth performance.

Predicting Growth and Carcass Traits in Swine Using Microbiome Data and Machine Learning Algorithms

In this paper, we evaluated the power of microbiome measures taken at three time points over the growth test period (weaning, 15 and 22 weeks) to foretell growth and carcass traits in 1039 individuals of a line of crossbred pigs. We measured prediction accuracy as the correlation between actual and predicted phenotypes in a five-fold cross-validation setting. Phenotypic traits measured included live weight measures and carcass composition obtained during the trial as well as at slaughter. We employed a null model excluding microbiome information as a baseline to assess the increase in prediction accuracy stemming from the inclusion of operational taxonomic units (OTU) as predictors. We further contrasted performance of models from the Bayesian alphabet (Bayesian Lasso) as well machine learning approaches (Random Forest and Gradient Boosting) and semi-parametric kernel models (Reproducing Kernel Hilbert space). In most cases, prediction accuracy increased significantly with the inclusion of microbiome data. Accuracy was more substantial with the inclusion of microbiome information taken at weeks 15 and 22, with values ranging from approximately 0.30 for loin traits to more than 0.50 for back fat. Conversely, microbiome composition at weaning resulted in most cases in marginal gains of prediction accuracy, suggesting that later measures might be more useful to include in predictive models. Model choice affected predictions marginally with no clear winner for any model/trait/time point. We, therefore, suggest average prediction across models as a robust strategy in fitting microbiome information. In conclusion, microbiome composition can effectively be used as a predictor of growth and composition traits, particularly for fatness traits. The inclusion of OTU predictors could potentially be used to promote fast growth of individuals while limiting fat accumulation. Early microbiome measures might not be good predictors of growth and OTU information might be best collected at later life stages. Future research should focus on the inclusion of both microbiome as well as host genome information in predictions, as well as the interaction between the two. Furthermore, the influence of the microbiome on feed efficiency as well as carcass and meat quality should be investigated.

Occurrence and contamination profiles of antibiotic resistance genes from swine manure to receiving environments in Guangdong Province southern China

Livestock farms are commonly regarded as the main sources of antibiotic resistance genes (ARGs), emerging pollutants with potential implications for human health, in the environment. This study investigated the occurrence and contamination profiles of nine ARGs of three types from swine manure to receiving environments (soil and water) in Guangdong Province, southern China. All ARGs occurred in 100% of swine manure samples. Moreover, the absolute concentration of total ARGs varied from 3.01 × 108 to 7.18 × 1014 copies/g, which was significantly higher than that in wastewater and manured soil (p < 0.05). Regarding the distribution characteristics of ARGs in swine manure, wastewater and manured soil, the tetracycline resistance gene tetO was predominant. ARGs in swine manure were relatively stable among swine growth periods after the nursery period. The ARG concentration did not differ significantly between manured and unmanured soil (p > 0.05). However, the number of ARGs (ermB, qnrS, acc(6′)-Ib, tetM, tetO and tetQ) decreased but were not eliminated by wastewater treatment components (p < 0.05). Based on correlation analysis, the tetracycline resistance genes tetQ and tetW in swine manure and the macrolide resistance genes ermB and ermF in wastewater were more easily spread than were other ARGs onto soil when the substances were applied as fertilizers. Therefore, effective removal and a standard permissible environmental level of ARGs should be established to control the risk of spreading ARGs in the environment.

Serial Optical Coherence Tomography at Baseline, 7 Days, and 1, 3, 6 and 12 Months After Bioresorbable Scaffold Implantation in a Growing Porcine Model

Little is known about serial changes in lumen and device dimensions after bioresorbable scaffold implantation in a growing animal model. Methods and Results: ABSORB (n=14) or bare metal stents (ICROS amg [Abbott Vascular, Santa Clara, CA, USA], Winsen-Luhe, Germany; n=15) were implanted in the coronary arteries of domestic swine (a hybrid of Finnish-Norwegian Landrace swine) weighing 30-35 kg. Angiography and optical coherence tomography (OCT) were performed immediately after implantation and repeated at 7 days, 1, 3, 6 and 12 months after the index procedure. One month after implantation, mean lumen area decreased relative to baseline in both groups (relative area change from baseline, -41.4±15.6% for ABSORB vs. -20.9±18.6% for ICROS) while mean device area decreased only in the ABSORB group (relative area change: -11.1±9.4% vs. +0.14±7.95%, respectively). At 12 months, mean lumen area increased relative to baseline in both groups (relative area change from baseline, +55.6±22.4% vs. +32.3±83.6%, respectively) in accordance with the swine growth weighing up to 260-300 kg. Mean device area in the ICROS group remained stable whereas that in the ABSORB group began to increase between 3 and 6 months along with the vessel growth (relative area change: +107.8±25.7% vs. +0.14±7.95%). In the growing porcine model, ABSORB was associated with greater extent of recoil 1 month after implantation compared with ICROS but demonstrated substantial adaptability to vessel growth in late phase.

Swine growth physiology

Swine growth physiology

Transfer of Deoxynivalenol (DON) through Placenta, Colostrum and Milk from Sows to Their Offspring during Late Gestation and Lactation.

Deoxynivalenol (DON) contamination of feed may result in reduced growth, feed refusal, immunosuppression, and health problems in swine. Piglets can be exposed to DON via placenta before birth and via milk during lactation. The extent of early-life exposure of piglets to DON is, however, not fully known. This study was therefore aimed at investigating DON uptake in sows fed with naturally contaminated diets, DON transfer across placenta during late gestation, and transfer of DON to piglets via colostrum and milk. Forty-four crossbred sows were evaluated from day 93 ± 1 of gestation until weaning of piglets and fed with feed made from naturally DON-contaminated oats at three concentration levels: (1) control (DON < 0.2 mg/kg), (2) DON level 1 (1.4 mg DON/kg), and (3) DON level 2 (1.7 mg DON/kg). The transfer of DON to the piglets was evaluated in 15 sows, with repeated sampling of blood and milk from the sows and blood samples from five piglets of each litter. The piglet/sow plasma DON ratio and milk/plasma (M/P) DON ratio in sows were calculated to estimate the degree of transfer. Piglet/sow plasma ratios were 2.14 at birth, 2.30 within 12–36 h after parturition, 0.08 on day 7, 0.16 on day 21, and 0.20 at weaning. M/P ratios were 0.92, 1.11, 0.94, 1.21, and 0.90, respectively. The results indicate that DON is efficiently transferred across placenta and into milk. However, the low piglet/sow plasma ratios at mid-lactation to weaning indicate that the piglets were most strongly exposed to DON in early life, despite the high M/P ratios and efficient secretion of DON in milk throughout the entire lactation.

BOARD-INVITED REVIEW: Arginine nutrition and metabolism in growing, gestating, and lactating swine.

Arginine (Arg) has traditionally not been considered as a deficient nutrient in diets for gestating or lactating swine due to the assumption that these animals can synthesize sufficient amounts of Arg to meet their physiological needs. The lack of full knowledge about Arg nutrition has contributed to suboptimal efficiency of pork production. Over the past 25 yr, there has been growing interest in Arg metabolism in the pig, which is an agriculturally important species and a useful model for studying human biology. Arginine is a highly abundant amino acid in tissues of pigs, a major amino acid in allantoic fluid, and a key regulator of gene expression, cell signaling, and antioxidative reactions. Emerging evidence suggests that dietary supplementation with 0.5% to 1% Arg maintains gut health and prevents intestinal dysfunction in weanling piglets, while enhancing their growth performance and survival. Also, the inclusion of 1% Arg in diets is required to maximize skeletal muscle accretion and feed efficiency in growing pigs, whereas dietary supplementation with 1% Arg reduces muscle loss in endotoxin-challenged pigs. Furthermore, supplementing 0.83% Arg to corn- and soybean meal-based diets promotes embryonic/fetal survival in swine and milk production by lactating sows. Thus, an adequate amount of dietary Arg as a quantitatively major nutrient is necessary to support maximum growth, lactation, and reproduction performance of swine. These results also have important implications for improving the nutrition and health of humans and other animals.

L-Glutamate nutrition and metabolism in swine.

L-Glutamate (Glu) has traditionally not been considered as a nutrient needed in diets for humans and other animals (including swine) due to the unsubstantiated assumption that animals can synthesize sufficient amounts of Glu to meet their needs. The lack of knowledge about Glu nutrition has contributed to suboptimal efficiency of global livestock production. Over the past 25years, there has been growing interest in Glu metabolism in the pig, which is an agriculturally important species and also a useful model for studying human biology. Because of analytical advances in its analysis, Glu is now known to be a highly abundant free amino acid in milk and intracellular fluid, a major constituent of food and tissue proteins, and a key regulator of gene expression, cell signaling, and anti-oxidative reactions. Emerging evidence shows that dietary supplementation with 2% Glu maintains gut health and prevents intestinal dysfunction in weanling piglets, while enhancing their growth performance and survival. In addition, the inclusion of 2% Glu is required for dietary arginine to maximize the growth performance and feed efficiency in growing pigs, whereas dietary supplementation with 2% Glu reduces the loss of skeletal muscle mass in endotoxin-challenged pigs. Furthermore, supplementing 2% Glu to a corn- and soybean-meal-based diet promotes milk production by lactating sows. Thus, an adequate amount of dietary Glu as a quantitatively major nutrient is necessary to support maximum growth, development, and production performance of swine. These results also have important implications for improving the nutrition and health of humans and other animals.