Determination of gastrointestinal tract colonization sites from feedlot cattle transiently shedding or super-shedding Escherichia coli O157:H7 at harvest.

AIMS: The objective of the study was to determine levels of Escherichia coli O157:H7 colonization in the gastrointestinal tract (GIT) of naturally shedding cattle shedding the pathogen at low- or super-shedder levels. METHODS AND RESULTS: Over 2 years, feedlot cattle were sampled multiple times for faecal shedding of E. coli O157:H7. Just prior to harvest (1-2 days), animals that were super-shedders (≥104  CFU per gram of faeces) were specifically identified, and based on the longer term screening data, pen cohorts that were low-shedders (years 1 and 2) or chronic-shedders (year 1) were also identified. At harvest, samples were collected from throughout the GIT, including the rectoanal junction (RAJ) for enumeration and enrichment of E. coli O157:H7. The mouth samples exhibited the greatest prevalence for the pathogen, and the abomasum and rumen exhibited the lowest prevalence (P < 0·05). Super-shedders had significantly greater prevalence for all GIT locations except the mouth and abomasum compared to low-shedders, but the super-shedders were the only animals with positive abomasum samples. Samples from the super-shedders were enumerable for most GIT locations, and the rectum and RAJ locations were the only locations that were significantly greater than other locations (P < 0·05). CONCLUSIONS: Across all animals naturally exposed to E. coli O157:H7, the risk of ingestion is high, but rumen and abomasum are potential barriers to passage. In super-shedders, the passage through the GIT was greater, allowing colonization in the rectum and at the RAJ. SIGNIFICANCE AND IMPACT OF THE STUDY: Escherichia coli O157:H7 low-shedding cattle had lower pathogen levels throughout the GIT, indicating intrinsic GIT factors to these cattle may reduce pathogen passage through the GIT, including the abomasum, and minimize risk of RAJ colonization.

Porcine single nucleotide polymorphisms and their functional effect: an update.

OBJECTIVE: To aid in the development of a comprehensive list of functional variants in the swine genome, single nucleotide polymorphisms (SNP) were identified from whole genome sequence of 240 pigs. Interim data from 72 animals in this study was published in 2017. This communication extends our previous work not only by utilizing genomic sequence from additional animals, but also by the use of the newly released Sscrofa 11.1 reference genome. RESULTS: A total of 26,850,263 high confidence SNP were identified, including 19,015,267 reported in our previously published results. Variation was detected in the coding sequence or untranslated regions (UTR) of 78% of the genes in the porcine genome: 1729 loss-of-function variants were predicted in 1162 genes, 12,686 genes contained 64,232 nonsynonymous variants, 250,403 variants were present in UTR of 15,739 genes, and 15,284 genes contained 90,939 synonymous variants. In total, approximately 316,000 SNP were classified as being of high to moderate impact (i.e. loss-of-function, nonsynonymous, or regulatory). These high to moderate impact SNP will be the focus of future genome-wide association studies.

Relationships between inflammation- and immunity-related transcript abundance in the rumen and jejunum of beef steers with divergent average daily gain.

The bovine rumen papillae are in contact with a wide array of microorganisms and the metabolites they produce, which may activate an inflammatory and/or immune response. Cytokines, chemokines and their receptor genes were tested for differential expression in the rumen and jejunum of beef steers with greater and lesser average daily body weight gain (ADG) near the average daily dry matter intake (DMI) for the population. Angus-sired steers (n = 16) were used to represent the greater (ADG = 2.2 ± 0.07 kg/day; DMI = 10.1 ± 0.05 kg/day) and lesser (ADG = 1.7 ± 0.05 kg/day; DMI = 10.1 ± 0.05 kg/day) ADG groups with eight steers each. Rumen epithelium and jejunum mucosal samples were collected at slaughter, and gene expression was evaluated using a commercially available qRT-PCR array containing 84 genes representing chemokines, cytokines and their receptors. None of the genes on the array were differentially expressed in the jejunum of the steers with greater vs. lesser ADG. However, in the rumen, two chemokine genes (CCL11, CXCL5) and one receptor gene (IL10RA) were detected as differentially expressed (P < 0.05). The genes IL1A, BMP2, CXCL12 and TNFSF13 also displayed trends for differential expression (P < 0.10). All of the genes identified were lower in transcript abundance in the greater ADG animals. Thus, greater ADG steers have a lesser inflammatory response in the rumen papillae, which may lead to a more efficient use of nutrients.

Differential gene expression in the duodenum, jejunum and ileum among crossbred beef steers with divergent gain and feed intake phenotypes.

Small intestine mass and cellularity were previously associated with cattle feed efficiency. The small intestine is responsible for the digestion of nutrients and absorption of fatty acids, amino acids and carbohydrates, and it contributes to the overall feed efficiency of cattle. The objective of this study was to evaluate transcriptome differences among the small intestine from cattle with divergent gain and feed intake. Animals most divergent from the bivariate mean in each of the four phenotypic Cartesian quadrants for gain × intake were selected, and the transcriptomes of duodenum, jejunum and ileum were evaluated. Gene expression analyses were performed comparing high gain vs. low gain animals, high intake vs. low intake animals and each of the phenotypic quadrants to all other groups. Genes differentially expressed within the high gain-low intake and low gain-high intake groups of animals included those involved in immune function and inflammation in all small intestine sections. The high gain-high intake group differed from the high gain-low intake group by immune response genes in all sections of the small intestine. In all sections of small intestine, animals with low gain-low intake displayed greater abundance of heat-shock genes compared to other groups. Several over-represented pathways were identified. These include the antigen-processing/presentation pathway in high gain animals and PPAR signaling, starch/sucrose metabolism, retinol metabolism and melatonin degradation pathways in the high intake animals. Genes with functions in immune response, inflammation, stress response, influenza pathogenesis and melatonin degradation pathways may have a relationship with gain and intake in beef steers.

Plasma concentrations of acyl-ghrelin are associated with average daily gain and feeding behavior in grow-finish pigs.

The objectives of this study were to determine the effect of sex, sire line, and litter size on concentrations of acyl-ghrelin and total ghrelin in plasma of grow-finish pigs and to understand the relationship of plasma concentrations of ghrelin with feeding behavior, average daily gain (ADG), and back fat in grow-finish swine. Yorkshire-Landrace crossbred dams were inseminated with semen from Yorkshire, Landrace, or Duroc sires. Within 24 h of birth, pigs were cross-fostered into litter sizes of normal (N; >12 pigs/litter) or small (S; ≤ 9 pigs/litter). At 8 wk of age, pigs (n = 240) were blocked by sire breed, sex, and litter size and assigned to pens (n = 6) containing commercial feeders modified with a system to monitor feeding behavior. Total time eating, number of daily meals, and duration of meals were recorded for each individual pig. Body weight was recorded every 4 wk. Back fat and loin eye area were recorded at the conclusion of the 12-wk feeding study. A blood sample was collected at week 7 of the study to quantify concentrations of acyl- and total ghrelin in plasma. Pigs from small litters weighed more (P < 0.05) and tended (P = 0.07) to be fatter than pigs from normal litters. Postnatal litter size did not affect ADG, feeding behavior, or concentrations of ghrelin in plasma during the grow-finish phase. Barrows spent more time eating (P < 0.001) than gilts, but the number of meals and concentrations of ghrelin did not differ with sex of the pig. Pigs from Duroc and Yorkshire sires had lesser (P < 0.0001) concentrations of acyl-ghrelin than pigs from Landrace sires, but plasma concentrations of total ghrelin were not affected by sire breed. Concentrations of acyl-ghrelin were positively correlated with the number of meals and negatively correlated with meal length and ADG (P < 0.05). A larger number of short-duration meals may indicate that pigs with greater concentrations of acyl-ghrelin consumed less total feed, which likely explains why they were leaner and grew more slowly. Acyl-ghrelin is involved in regulating feeding behavior in pigs, and measuring acyl-ghrelin is important when trying to understand the role of this hormone in swine physiology.

Lysozyme as an alternative to growth promoting antibiotics in swine production.

Lysozyme is a naturally occurring enzyme found in bodily secretions such as tears, saliva, and milk. It functions as an antimicrobial agent by cleaving the peptidoglycan component of bacterial cell walls, which leads to cell death. Antibiotics are also antimicrobials and have been fed at subtherapeutic levels to swine as growth promoters. These compounds benefit swine producers by minimizing production losses by increasing feed efficiency and decreasing susceptibility to bacterial infection and disease. This manuscript reviews the knowledge of the effects of lysozyme, as compared to traditional subtherapeutic antibiotics in swine feed, on pig performance and health. It is clear from decades of studies that antibiotic use in feeds increases pig performance, particularly in the nursery. Similarly, lysozyme, as a feed additive, increases growth and feed efficiency. While the mechanism by which antibiotics and lysozyme improve performance is not clearly understood, both of these feed additives improve gastrointestinal health, improve the metabolic profile, and alter the gastrointestinal bacteria ecology of swine. Therefore, lysozyme is a suitable alternative to growth-promoting subtherapeutic antibiotic use in swine feed.

Differences in transcript abundance of genes on BTA15 located within a region associated with gain in beef steers.

Using results from a previous GWAS, we chose to evaluate seven genes located within a 229Kb region on BTA15 for variation in RNA transcript abundance in a library of tissue samples that included adipose, liver, rumen papillae, spleen, muscle, and small intestine epithelial layers from the duodenum, ileum and jejunum collected from steers (n = 14) with positive and negative residual GN near mean dry matter intake (DMI). The genes evaluated were two olfactory receptor-like genes (LOC525033 and LOC618173), RRM1, STIM1, RHOG, PGAP2, and NUP98. The rumen papillae transcript abundance of RHOG was positively correlated with residual GN (P = 0.02) and ruminal STIM1 exhibited a trend towards an association with residual GN (P = 0.08). The transcript abundance of one olfactory receptor (LOC618173) in the ileum was also positively associated with residual GN (P = 0.02) and PGAP2 and LOC525033 in the ileum displayed trends for association with GN (P ≤ 0.1). To further evaluate the differential expression detected in the ileum and rumen of these animals, the transcript abundance of STIM1 and RHOG in the rumen and of PGAP2 and the olfactory receptors in the ileum were assessed in an additional group of 32 animals with divergent average daily gain (ADG) and average daily feed intake (ADFI) collected over two groups. The olfactory receptor, LOC525033, was not expressed in the ileum for the majority of these animals. Only RHOG showed a slight, but non-significant trend towards greater expression in animals with greater gain. We have detected differences in the transcript abundance of genes within this region in the rumen and ileum of animals selected for greater and less residual gain; however, we were unable to validate the expression of these genes in the larger group of cattle possibly due to the differences in phenotype or contemporary group.

Contributions of the maternal uterine environment and piglet genotype on weaning survivability potential: II. Piglet growth, lactation performance, milk composition, and piglet blood profiles during lactation following reciprocal embryo transfers between Meishan and White crossbred gilts.

Crossbreeding studies between Meishan (MS) and Large White (LW) pigs have illustrated that increased piglet growth before weaning is attributed to the maternal genotype of LW dams. The objective of this study was to determine the contributions of the maternal uterine environment (MUE), piglet genotype (PigG), piglet age (PA), and their interactions on piglet growth, lactation performance, milk composition, and piglet blood profiles during lactation following reciprocal embryo transfers between MS and White crossbred (WC) gilts. Twenty-five successful pregnancies were generated by embryo transfer in 2 farrowing years representing all MUE × PigG combinations: MS × MS (n = 4 litters), MS × WC (n = 7 litters), WC × MS (n = 7 litters), and WC × WC (n = 7 litters). At d 1 and 10 and at weaning, piglets (n = 147, n = 96, and n = 94, respectively) were weighed and blood samples were collected and measured for hematocrit, hemoglobin, glucose, nitrogen, NEFA, albumin, lactate, and cortisol. In addition, sows were manually milked from a medial mammary gland to determine milk composition. All data were analyzed by ANOVA using MIXED model procedures with the fixed effects of MUE, PigG, PA, and their interactions. Piglet weight was greater (P < 0.001) in piglets from WC dams compared to MS dams at d 10 and weaning but not at d 1. In addition, ADG were greater (P < 0.05) from piglets from WC dams compared to MS dams throughout lactation. However, milk composition was greater (P < 0.05) for GE and fat content from MS dams compared to WC dams, illustrating differences in milk quality between the breeds. There were significant MUE × PigG × PA interactions for hematocrit and hemoglobin levels in which greater (P < 0.001) levels were observed in MS piglets, irrespective of MUE, at d 1 of lactation and in MS piglets from MS dams at d 10 of lactation. Blood glucose was greater (P = 0.01) at d 1 in piglets from WC dams regardless of PigG but, at weaning, glucose was greater (P = 0.01) in WC piglets regardless of MUE. Serum NEFA levels were greater (P = 0.02) in piglets from MS dams throughout the lactation period. This study demonstrated that WC dams were superior to MS dams for piglet growth during lactation, in agreement with previous crossbreeding studies. However, blood components measured displayed complex interactions between the piglet and maternal breed, which signify possible mechanisms for improved preweaning survivability but slower lactational growth of MS piglets.

Effect of lysozyme or antibiotics on faecal zoonotic pathogens in nursery pigs.

AIMS: The objective of this study was to determine the effect of lysozyme and antibiotics on zoonotic pathogen shedding in faeces from nursery pigs housed without and with an indirect disease challenge. METHODS AND RESULTS: Two replicates of approximately 650 pigs each were weaned and randomly assigned to one of 24 pens in either a nursery room that had been fully disinfected or a nursery room left unclean. Pigs were randomly assigned to control diet (Control), control diet + antibiotics (Antibiotic; chlortetracycline and tiamulin), or control diet + lysozyme (Lysozyme; 100 mg kg(-1) diet). Rectal swab samples were collected on day 0 and 28 of treatment, and enriched and cultured for Campylobacter spp. and shiga-toxigenic Escherichia coli (STEC). Enrichments from rectal swab samples also were analysed for presence of enterohaemorrhagic E. coli (EHEC) virulence genes (hlyA, eae, stx1 and stx2). Room hygiene had little effect on day 28 results. Percentage of samples culture positive for Campylobacter spp. was lowest for lysozyme diets (P < 0·01), but similar for control and antibiotic diets (43·2, 83·7, and 84·8 respectively). Diet had little effect on the EHEC virulence genes hlyA or eae (P > 0·1), but there was a tendency for fewer samples positive for stx1/stx2 in antibiotic or lysozyme diet groups (P < 0·07) compared to control diet (1·2, 2·1 and 5·8% respectively). Salmonella spp. and specific STEC types tested were rarely detected in the study. CONCLUSIONS: In nursery swine, room hygiene had little effect on pathogen shedding. Dietary chlortetracycline and tiamulin did not reduce pathogen shedding but dietary lysozyme reduced faecal shedding of Campylobacter. SIGNIFICANCE AND IMPACT OF THE STUDY: Lysozyme can effectively replace antibiotics in the diet of nursery swine and can be effective for pathogen control.

Lysozyme as an alternative to antibiotics improves performance in nursery pigs during an indirect immune challenge.

Lysozyme is a 1,4-ß-N-acetylmuramidase that has antimicrobial properties. The objective of this study was to determine the effect of lysozyme and antibiotics on growth performance and immune response during an indirect immune challenge. Two replicates of 600 pigs each were weaned from the sow at 26 d of age, blocked by litter and sex, and then randomly assigned to 1 of 24 pens in either a nursery room that had been fully disinfected or a nursery room left unclean since the previous group of pigs. Within a room, pigs were randomly assigned to either control diets (2 phase nursery regime), control diets + antibiotics (chlortetracycline/tiamulin hydrogen fumarate), or control diets + lysozyme (100 mg/kg diet). Pig weights and feed disappearance were measured and blood was collected on d 0, 14, and 28 of treatment. A group of 20 pigs were killed at 24 d of age for initial body composition analysis and 10 pigs of median weight were killed per diet room combination for body composition analysis after 28 d of treatment. Control + antibiotics and control + lysozyme-fed pigs grew at a faster rate for the 28-d study compared to control pigs (318 ± 14,320 ± 15 vs. 288 ± 15 g/d, respectively; P < 0.05), regardless of nursery environment (P > 0.05). The indirect immune challenge did not alter growth performance from d 0 to 14 of treatment but decreased ADG from d 14 to 28 of the study (415 ± 15 vs. 445 ± 13 g/d ;: P < 0.05). Feed intake was not altered by the nursery environment (P > 0.61) or dietary treatments (P > 0.10), but feed efficiency was worsened by the indirect immune challenge (P < 0.05) and improved by both control + antibiotics and control + lysozyme diets (P < 0.01). The immune challenge did not alter nutrient accretion (P > 0.25), but both control + antibiotics and control + lysozyme pigs had decreased accretion of whole-body lipid (P < 0.01) and increased accretion of protein (P < 0.09). Blood levels of tumor necrosis factor-α (TNF-α; P < 0.01), haptoglobin (P < 0.09), and C-reactive protein (CRP; P < 0.01) were higher due to the indirect immune challenge compared to pigs reared in the clean nursery (P < 0.05). In addition, pigs consuming antibiotics or lysozyme had lower TNF-α, haptoglobin, and CRP compared to control pigs, regardless of nursery environment (P < 0.04). Thus, lysozyme is a suitable alternative to antibiotics in swine nursery diets, and lysozyme ameliorates the effects of a chronic indirect immune challenge.

DNA polymorphisms and transcript abundance of PRKAG2 and phosphorylated AMP-activated protein kinase in the rumen are associated with gain and feed intake in beef steers.

Beef steers with variation in feed efficiency phenotypes were evaluated previously on a high-density SNP panel. Ten markers from rs110125325-rs41652818 on bovine chromosome 4 were associated with average daily gain (ADG). To identify the gene(s) in this 1.2-Mb region responsible for variation in ADG, genotyping with 157 additional markers was performed. Several markers (n = 41) were nominally associated with ADG, and three of these, including the only marker to withstand Bonferroni correction, were located within the protein kinase, AMP-activated, gamma 2 non-catalytic subunit (PRKAG2) gene. An additional population of cross-bred steers (n = 406) was genotyped for validation. One marker located within the PRKAG2 loci approached a significant association with gain. To evaluate PRKAG2 for differences in transcript abundance, we measured expression in the liver, muscle, rumen and intestine from steers (n = 32) with extreme feed efficiency phenotypes collected over two seasons. No differences in PRKAG2 transcript abundance were detected in small intestine, liver or muscle. Correlation between gene expression level of PRKAG2 in rumen and average daily feed intake (ADFI) was detected in both seasons (P < 0.05); however, the direction differed by season. Lastly, we evaluated AMP-activated protein kinase (AMPK), of which PRKAG2 is a subunit, for differences among ADG and ADFI and found that the phosphorylated form of AMPK was associated with ADFI in the rumen. These data suggest that PRKAG2 and its mature protein, AMPK, are involved in feed efficiency traits in beef steers. This is the first evidence to suggest that rumen AMPK may be contributing to ADFI in cattle.

The effects of Capn1 gene inactivation on skeletal muscle growth, development, and atrophy, and the compensatory role of other proteolytic systems.

Myofibrillar protein turnover is a key component of muscle growth and degeneration, requiring proteolytic enzymes to degrade the skeletal muscle proteins. The objective of this study was to investigate the role of the calpain proteolytic system in muscle growth development using µ-calpain knockout (KO) mice in comparison with control wild-type (WT) mice, and evaluate the subsequent effects of silencing this gene on other proteolytic systems. No differences in muscle development between genotypes were observed during the early stages of growth due to the up regulation of other proteolytic systems. The KO mice showed significantly greater m-calpain protein abundance (P < 0.01) and activity (P < 0.001), and greater caspase 3/7 activity (P < 0.05). At 30 wk of age, KO mice showed increased protein:DNA (P < 0.05) and RNA:DNA ratios (P < 0.01), greater protein content (P < 0.01) at the expense of lipid deposition (P < 0.05), and an increase in size and number of fast-twitch glycolytic muscle fibers (P < 0.05), suggesting that KO mice exhibit an increased capacity to accumulate and maintain protein in their skeletal muscle. Also, expression of proteins associated with muscle regeneration (neural cell adhesion molecule and myoD) were both reduced in the mature KO mice (P < 0.05 and P < 0.01, respectively), indicating less muscle regeneration and, therefore, less muscle damage. These findings indicate the concerted action of proteolytic systems to ensure muscle protein homeostasis in vivo. Furthermore, these data contribute to the existing evidence of the importance of the calpain system's involvement in muscle growth, development, and atrophy. Collectively, these data suggest that there are opportunities to target the calpain system to promote the growth and/or restoration of skeletal muscle mass.

Lysozyme as an alternative to antibiotics improves growth performance and small intestinal morphology in nursery pigs.

Lysozyme is a 1,4-ß-N-acetylmuramidase that has antimicrobial properties. The objective of this experiment was to determine if lysozyme in nursery diets improved growth performance and gastrointestinal health of pigs weaned from the sow at 24 d of age. Two replicates of 96 pigs (192 total; 96 males, 96 females) were weaned from the sow at 24 d of age, blocked by BW and gender, and then assigned to 1 of 24 pens (4 pigs/pen). Each block was randomly assigned 1 of 3 dietary treatments for 28 d: control (two 14-d phases), control + antibiotics (carbadox/copper sulfate), or control + lysozyme (100 mg/kg diet). Pigs were weighed and blood sampled on d 0, 14, and 28 of treatment. Blood was analyzed for plasma urea nitrogen (PUN) and IgA. At 28 d, pigs were killed, and samples of jejunum and ileum were collected and fixed for intestinal morphology measurements. An additional jejunum sample was taken from the 12 pigs with the median BW per treatment to determine transepithelial electrical resistance (TER). Pigs consuming antibiotics or lysozyme grew at a faster rate than control pigs (0.433 ± 0.009 and 0.421 ± 0.008 vs. 0.398 ± 0.008 kg/d, respectively; P < 0.03), which resulted in heavier ending BW (20.00 ± 0.31, 19.8 ± 0.29, and 18.83 ± 0.32 kg, respectively; P < 0.03). Feed intake was not different (P > 0.48), but G:F was improved in pigs consuming antibiotics or lysozyme (0.756 ± 0.014, 0.750 ± 0.021, and 0.695 ± 0.019 kg/kg; P < 0.05). Immunoglobulin A (P < 0.03) and PUN (P < 0.01) increased during the experiment, regardless of dietary treatment (P > 0.48). Dietary treatment did not affect TER (P > 0.37), but gilts had lower TER compared with barrows (P < 0.04). No differences in villi height or crypt depth were observed in the ileum (P > 0.53). However, jejunum villi height was increased and crypt depth was decreased in pigs consuming antibiotics or lysozyme (P < 0.001), resulting in an increased villi height:crypt depth of 72% (P < 0.001). Thus, we concluded that lysozyme is a suitable alternative to carbadox/copper sulfate diets fed to pigs weaned from the sow at 24 d of age.

Effects of antimicrobials fed as dietary growth promoters on faecal shedding of Campylobacter, Salmonella and shiga-toxin producing Escherichia coli in swine.

AIMS: To determine whether antimicrobials commonly used in swine diets affect zoonotic pathogen shedding in faeces. METHODS AND RESULTS: Barrows (n = 160) were sorted into two treatments at 10 weeks of age (week 0 of the study), and fed growing, grow finishing and finishing diets in 4-week feeding periods. For each feeding phase, diets were prepared without (A-) and with (A+) dietary antimicrobials (chlortetracycline, 0-8 week; bacitracin, 9-12 week) typical of the United States. At week 0, 4, 8, 9, 10 and 12 of the study, faecal swabs or grabs were collected for analyses. Campylobacter spp. was absent at week 0, but prevalence increased over time with most isolates being identified as Campylobacter coli. When chlortetracycline was used in A+ diets (week 4 and 8), prevalence for Campylobacter spp., pathogenic Escherichia coli O26 and stx genes was lower in faeces. On week 12 after the shift to bacitracin, Campylobacter spp. and stx genes were higher in faeces from piglets fed A+ diet. Pathogenic E. coli serogroups O103 and O145 were isolated throughout the study and their prevalence did not differ due to diet. Pathogenic E. coli serogroups O111 and O121 were never found in the piglets, and Salmonella spp. prevalence was low. CONCLUSIONS: In production swine, growing diets with chlortetracycline may have reduced pathogen shedding compared with the A-growing diets, whereas finishing diets with bacitracin may have increased pathogen shedding compared with the A-finishing diet. SIGNIFICANCE AND IMPACT OF THE STUDY: Inclusion of antimicrobials in the diet can affect zoonotic pathogen shedding in faeces of swine.

Contributions of the maternal uterine environment and piglet genotype on weaning survivability potential: I. Development of neonatal piglets after reciprocal embryo transfers between Meishan and White crossbred gilts.

In commercial pigs, the greatest susceptibility for pre-weaning mortality occurs in low birth-weight piglets. Despite their overall decreased birth weight, Meishan (MS) piglets have decreased pre-weaning mortality rates compared with contemporary Western breeds. The objective of the current study was to determine the contributions of the maternal uterine environment, piglet genotype, and their interaction on the development of neonatal piglets pertaining to pre-weaning survivability using reciprocal embryo transfer between MS and White crossbred (WC) pigs. Twenty-five successful pregnancies were produced from 2 farrowing seasons, generating litters of maternal uterine environment (MUE) by piglet genotype (PigG) combinations; MS × MS (n = 4 litters), MS × WC (n = 7 litters), WC × MS (n = 7 litters), and WC × WC (n = 7 litters). At approximately 24 h of age (Day 1), piglets (n = 173) were weighed and a blood sample was taken. Hematocrit, hemoglobin, glucose, plasma urea nitrogen, albumin, NEFA, lactate, and cortisol were measured in all blood samples. Representative piglets (n = 46) from each litter were harvested and body measurements (i.e., organ weights, tissue glycogen content, and body composition) were determined. Piglet data were analyzed by ANOVA using MIXED model procedures. Both MUE (P < 0.001) and PigG (P < 0.01) affected piglet BW, illustrating that piglets gestated in WC gilts were heavier than piglets gestated in MS gilts, and WC piglets were heavier than MS piglets. Serum albumin concentrations were increased (P < 0.05) in MS piglets compared with WC piglets, indicating greater liver maturity. Significant MUE × PigG interactions were observed for hematocrit and hemoglobin, in which the greatest concentrations were observed in MS piglets gestated in MS and WC gilts, and the lowest concentrations were observed in WC piglets gestated in WC gilts, demonstrating increased oxygen-carrying capability. The percentage of fat and nitrogen, as well as the GE of the body, were greater (P < 0.05) in MS piglets, indicating greater energy stores. Liver, bicep femoris, and LM glycogen concentrations were greater (P < 0.01) in WC piglets compared with MS piglets, demonstrating increased glycogen catabolism in MS piglets. This study demonstrated limited interactions between the maternal uterine environment and piglet genotype on weaning survivability potential, suggesting that the MS piglet is a viable model for pre-weaning survivability.

Granulated lysozyme as an alternative to antibiotics improves growth performance and small intestinal morphology of 10-day-old pigs.

Lysozyme is a 1,4-ß-N-acetylmuramidase that has antimicrobial properties. The objective of this experiment was to determine the effect of a purified granulated lysozyme, compared with antibiotics, on growth performance, small intestinal morphology, and Campylobacter shedding in 10-d-old pigs. Forty-eight pigs (n = 16 per treatment), with an initial BW of 4.0 ± 0.1 kg (P > 0.40), were weaned at 10 d of age, blocked by litter and sex, and assigned to pens (8 pigs/pen). Each block was randomly assigned to consume 1 of 3 liquid dietary treatments for 14 d: a control diet, the control diet + lysozyme (100 mg/kg of diet), or the control diet + antibiotics (neomycin and oxytetracycline, 16 mg/kg of diet). Pigs were weighed and blood was sampled on d 0, 7, and 14. Blood was analyzed for plasma urea N and IgA. After 14 d of treatment, pigs were killed and samples of the jejunum and ileum were collected and fixed to measure villus height and crypt depth. Rectal swabs were taken on d 0, 7, and 14 of treatment, and samples of ileal and cecal contents were taken at d 14 of treatment to determine the presence of Campylobacter. Pigs consuming lysozyme and antibiotics gained BW at a faster rate than did control pigs over the course of the study (402 ± 12 and 422 ± 14 g/d, respectively, vs. 364 ± 14 g/d; P < 0.02), resulting in heavier ending BW (9.9 ± 0.3, 9.9 ± 0.3, and 9.0 ± 0.2 kg for pigs in the lysozyme, antibiotic, and control groups, respectively; P < 0.03). Immunoglobulin A decreased and plasma urea N increased over the course of the study (P < 0.1), regardless of dietary treatment (P > 0.6). Crypt depth was increased in pigs fed lysozyme- and antibiotic-treated diets, compared with pigs fed the control diet, in both the jejunum (60.0 ± 2.8 and 62.2 ± 3.0 µm, respectively, vs. 50.7 ± 3.1 µm; P < 0.03) and ileum (76.0 ± 7.5 and 72.2 ± 5.0 µm, respectively, vs. 52.4 ± 3.5 µm; P < 0.02). Villus height did not differ in the jejunum (P > 0.2) but was increased in the ileum of pigs consuming the lysozyme- and antibiotic-treated diets, compared with pigs fed the control diet (312 ± 20 and 314 ± 10 µm, respectively, vs. 263 ± 15 µm; P < 0.4). Small intestinal total mucosa and mucosal protein concentrations, as well as disaccharidase-specific activities, were not altered by lysozyme or antibiotics (P > 0.05). Campylobacter was detected in 27% of control samples but in only 5% of samples from pigs fed antibiotics and 8% of samples from pigs fed lysozyme (P < 0.01). Thus, granulated lysozyme is a suitable alternative to antibiotics for 10-d-old pigs consuming manufactured liquid diets.

A low-fat liquid diet increases protein accretion and alters cellular signaling for protein synthesis in 10-day-old pigs.

Previous research showed that neonatal pigs respond to decreases in energy density of liquid diets with increased feed intake, resulting in similar performance to pigs fed a more energy-dense diet. The objective of this experiment was to determine whether a high- (25%, HF) or low-fat (2%, LF) liquid diet would affect nutrient accretion rate and select proteins involved in energy homeostasis and protein synthesis in early weaned pigs. Ninety-six pigs, with an initial BW of 3,637 +/- 85 g, were weaned from the sow at 10 d of age and utilized in a randomized complete block design. Pigs were blocked by BW and then assigned to pens (8 pigs/pen). Diets were formulated to provide a constant AA:ME ratio and were fed for 10 d. Pigs were killed at 10, 15, and 20 d of age, at which time blood and LM were collected, and carcasses were prepared for body composition analysis. Blood was analyzed for plasma urea nitrogen (PUN) and NEFA. Longissimus dorsi was analyzed via western immunoblot for mammalian target of rapamycin (mTOR) and adenosine 5' monophosphate-activated protein kinase (AMPK) phosphorylation. Pigs gained 347 +/- 11 g/d, which resulted in an ending BW of 6,858 +/- 135 g, regardless of dietary treatment (P > 0.49). Pigs fed the LF diet consumed 25% more milk than pigs fed the HF diet (2,853 +/- 86 vs. 2,269 +/- 79 g dry feed.pen(-1).d(-1); P < 0.01), which resulted in similar calculated ME intakes between dietary treatments (9.9 +/- 0.2 vs. 10.5 +/- 0.2 Mcal.pen(-1).d(-1); P > 0.5). Feed conversion (G:F) was 24% greater in HF-fed compared with LF-fed pigs (P < 0.01). Circulating NEFA (40 +/- 14 vs. 138 +/- 21 microEq/L; P < 0.01) and PUN (3.0 +/- 0.6 vs. 17.7 +/- 0.8 mM; P < 0.01) concentrations were less in LF pigs compared with HF pigs after 10 d of dietary treatments. Pigs consuming the LF diet had a 21% increase in protein accretion (50.5 +/- 2.8 vs. 61.2 +/- 2.8 g/d; P < 0.04) and a 71% reduced lipid accretion rate (28.8 +/- 2.0 vs. 8.3 +/- 2.3 g/d; P < 0.001). Phosphorylation of AMPK was 29% less (P < 0.03) in LF pigs compared with HF pigs, whereas mTOR phosphorylation was increased by 37% in LF pigs (P < 0.01). We conclude that feeding a LF liquid diet to pigs weaned from the sow at 10 d of age increases feed intake to regulate energy intake while maintaining growth performance. In addition, 10-d-old pigs consuming a liquid LF diet have increased protein deposition by a mechanism mediated through AMPK and mTOR.

The effects of dietary additives on faecal levels of Lactobacillus spp., coliforms, and Escherichia coli, and faecal prevalence of Salmonella spp. and Campylobacter spp. in US production nursery swine.

AIMS: In the United States, carbadox and copper sulfate are growth promoters commonly used in combination in nursery swine diets. Our aim was to determine how selected dietary additives affect selected bacterial populations and pathogens in nursery swine, and compare to larch extract, which contains potential antibacterial activities. METHODS AND RESULTS: Piglets were weaned and sorted into one of the four treatments: (i) basal diet without antimicrobials; (ii) basal diet with carbadox + copper sulfate; (iii) basal diet + 1000 ppm larch extract; or (iv) basal diet + 2000 ppm larch extract. Diets were fed for a 4-week period after weaning. In both trials, the carbadox + copper sulfate group consumed more feed over the 4-week period relative to the other three diet groups (P < 0.05), but did not gain significantly more weight. Faecal shedding of Salmonella spp. was not affected by dietary supplement in either trial, but faecal shedding of Campylobacter spp. was the lowest for the carbadox + copper sulfate diet. In faecal samples collected at the end of each trial, Lactobacillus spp. cell counts for the basal and larch extract diets were nearly 1.0 log(10) g(-1) faeces greater (P < 0.05) than the carbadox + copper sulfate group, whereas the coliforms and Escherichia coli were nearly 1.0 log(10) g(-1) faeces lower (P < 0.05). CONCLUSIONS: Compared to basal fed animals, supplementation with carbadox + copper sulfate significantly altered faecal E. coli, coliform bacteria and Lactobacillus spp. Larch extract has no benefit up to 0.2% of diet in regard to pathogen shedding, whereas carbadox + copper sulfate decreased faecal shedding of Campylobacter spp. SIGNIFICANCE AND IMPACT OF THE STUDY: Current swine management practices in the United States may be beneficial to managing Campylobacter spp. shedding in nursery swine, but also result in significant changes in the resident gastrointestinal microflora.

Pigs weaned from the sow at 10 days of age respond to dietary energy source of manufactured liquid diets and exogenous porcine somatotropin.

Previous research indicates that the neonatal pig does not alter feed intake in response to changes in the energy density of manufactured liquid diets. Also, the limited response of IGF-I to exogenous porcine ST (pST) previously observed in young pigs may be influenced by the source of dietary energy. Our objectives were to 1) determine the effect of a high-fat (HF; 25% fat and 4,639 kcal/kg ME; DM basis) or low-fat (LF; 2% fat and 3,481 kcal/kg ME; DM basis) manufactured liquid diet on pig performance; and 2) determine whether the limited response to exogenous pST in young pigs depends on the source of dietary energy. Two replicates of 60 pigs (n = 120; barrows and gilts distributed evenly), with an initial BW of 4,207 +/- 51 g, were weaned from the sow at 10 d of age and used in a randomized complete block design. Pigs were assigned by BW to one of six pens. Diets were formulated to provide a constant lysine:ME ratio and were fed on a pen basis for a duration of 9 d. On d 5, barrows and gilts within a pen were assigned randomly to receive either 0 or 120 microg of pST.kg BW(-1).d(-1) for 4 d. Pigs gained 336 +/- 9 g/d, which resulted in an ending BW of 7,228 +/- 120 g, regardless of dietary treatment (P > 0.15). Pigs fed the LF diet consumed 17% more DM per pen daily than pigs fed the HF diet (2,777 +/- 67 vs. 2,376 +/- 67 g/d, P < 0.01), but calculated ME intake did not differ between dietary treatments (P > 0.20). The G:F was 24% greater in HF- than in LF-fed pigs (P < 0.01). Plasma urea N concentrations were higher in the HF-fed pigs (11.0 +/- 0.6 mg/dL) than in pigs fed the LF diet (6.2 +/- 0.6 mg/dL; P < 0.05). Treatment with pST increased circulating IGF-I (P < 0.01) and decreased PUN (P < 0.01) concentration 32 and 25%, respectively, regardless of dietary treatment (P > 0.30). Circulating leptin averaged 1.8 +/- 0.1 ng/mL and was not affected by dietary treatment (P > 0.35) or pST (P > 0.40). These results suggest that the ST/IGF axis is responsive in the young pig and the increase in circulating IGF-I and growth is independent of the source of dietary energy. Also, young pigs respond to a lower energy density liquid diet with increased feed intake, without altering growth performance, apparently utilizing a mechanism other than circulating leptin.