Effects of a mannan-rich yeast cell wall-derived preparation on cecal concentrations and tissue prevalence of Salmonella Enteritidis in layer chickens

Salmonella Enteritidis (SE) has been the most common Salmonella serotype associated with foodborne infections in the last several years. Dietary applications of yeast-based preparations in feed have shown to reduce Salmonella colonization in chickens augmenting SE control strategies. This study was conducted to evaluate the effects of a mannan-rich yeast cell wall-derived preparation (Actigen^®) administered in feed at a rate of 400 g/ton on SE colonization in the cecum and internal organs of commercial layer chickens. Sixteen week-old layer pullets were orally challenged with a selected nalidixic acid resistant SE strain at a dose of 1.7×10^9 colony forming units (CFU) per bird. SE colonization was assessed by evaluating isolation rates from ovary and pooled liver/spleen samples as well as enumeration of SE in cecal pouches one week post-challenge. Recovery rates of SE from the ovaries of directly challenged birds receiving Actigen^® were significantly lower (P <0.02) than those in directly challenged birds fed an unsupplemented control diet. Recovery rates of SE from pooled liver/spleen samples were not significantly different between Actigen^®-treated pullets and controls (P = 0.22). Using direct plate count methods, cecal SE concentrations were 1 log₁₀ lower (P <0.001) in challenged pullets in the Actigen^®-supplemented group than in the challenged controls. The SE concentration distributions in the ceca were similar in groups testing positive and groups testing negative for SE in the ovaries and liver/spleens tissues. As a result, SE concentrations in the ceca could not be directly related to the occurrence or prevalence of SE in these tissues. In conclusion, Actigen^® supplementation appears to decrease the prevalence of SE in ovarian tissue and concentrations of SE in cecal contents and may be useful as a tool for reducing the risk of eggshell contamination and transovarian transmission of SE in eggs.

Zinc source modulates intestinal inflammation and intestinal integrity of broiler chickens challenged with coccidia and Clostridium perfringens

Two dietary sources of zinc (ZnSO4 or organic Zn) were tested in chickens challenged with coccidiosis (Co) or coccidiosis plus Clostridium perfringens (CoCPF). On day 14, the chickens were orally gavaged with ∼5,000 Eimeria maxima sporulated oocysts. On day 19, 20, and 21 chickens challenged with C. perfringens were given a broth culture containing 108 cfu of this bacterium. Productive performance parameters were determined at d 14, 21, and 28. On day 21, necrotic enteritis (NE) lesions were scored, and intestinal permeability was evaluated. Jejunum and cecal tonsils were collected for morphology and gene expression analysis. On day 21, organic Zn improved BW gain by 18.6% (P = 0.07), and FCR by 12% (P = 0.09) in CoCPF challenged chickens vs. birds fed ZnSO4. From 1 to 28, organic Zn increased BW gain (P = 0.02), and improved FCR (P = 0.03) vs. birds fed ZnSO4. At 21 d, NE lesions were only observed in CoCPF birds (P < 0.001), and mortality due to NE was only observed when CoCPF birds were fed ZnSO4 (P = 0.001). Organic Zn fed birds had increased villus height in the jejunum (P = 0.005) and decreased intestinal permeability (P = 0.01) vs. ZnSO4. In the jejunum, organic Zn fed birds showed a downregulation of expression of IL-8 (P = 0.02), and upregulation of IL-10 (P = 0.05) in CoCPF birds vs. ZnSO4- CoCPF birds. As main effect, birds supplemented with organic Zn had higher mRNA expression of TLR-2 (P = 0.02) and IgA (P = 0.01). In the cecal tonsils, organic Zn fed birds showed upregulation of iNOS (P = 0.008) in CoCPF birds vs. ZnSO4-CoCPF birds. Organic Zn supplementation reduced intestinal permeability and attenuated intestinal inflammation of broilers co-challenged with coccidia and C. perfringens.

Prepartal Energy Intake Alters Blood Polymorphonuclear Leukocyte Transcriptome During the Peripartal Period in Holstein Cows

In the dairy industry, cow health and farmer profits depend on the balance between diet (ie, nutrient composition, daily intake) and metabolism. This is especially true during the transition period, where dramatic physiological changes foster vulnerability to immunosuppression, negative energy balance, and clinical and subclinical disorders. Using an Agilent microarray platform, this study examined changes in the transcriptome of bovine polymorphonuclear leukocytes (PMNLs) due to prepartal dietary intake. Holstein cows were fed a high-straw, control-energy diet (CON; NE_L = 1.34 Mcal/kg) or overfed a moderate-energy diet (OVE; NE_L = 1.62 Mcal/kg) during the dry period. Blood for PMNL isolation and metabolite analysis was collected at −14 and +7 days relative to parturition. At an analysis of variance false discovery rate <0.05, energy intake (OVE vs CON) influenced 1806 genes. Dynamic Impact Approach bioinformatics analysis classified treatment effects on Kyoto Encyclopedia of Genes and Genomes pathways, including activated oxidative phosphorylation and biosynthesis of unsaturated fatty acids and inhibited RNA polymerase, proteasome, and toll-like receptor signaling pathway. This analysis indicates that processes critical for energy metabolism and cellular and immune function were affected with mixed results. However, overall interpretation of the transcriptome data agreed in part with literature documenting a potentially detrimental, chronic activation of PMNL in response to overfeeding. The widespread, transcriptome-level changes captured here confirm the importance of dietary energy adjustments around calving on the immune system.

252 EFFECTS OF LOW CIRCULATING PROGESTERONE CONCENTRATIONS DURING EARLY DIESTRUS ON THE ENDOMETRIAL TRANSCRIPTOME OF THE MARE

Progestational-induced changes in endometrial gene expression that are essential for maintenance of pregnancy have been reported in several species. In the horse, serum progesterone (P4) concentrations are routinely measured to assess progestational support of pregnancy and low P4 is implicated as a cause of embryo loss; however, there is little information available concerning changes in the endometrial transcriptome associated with low peripheral P4 concentrations. The objectives of this study were to evaluate changes in the endometrial mRNA transcriptome at Day 12 of the oestrous cycle between mares with normal v. low P4 concentrations. Mares (n = 6) were randomly assigned to control (placebo) or treatment cycles (125 mg of cloprostenol IM on Days 0 through 3 postovulation), and subsequently mares underwent the opposite treatment after a rest cycle. Blood samples were collected daily from the jugular vein. P4 concentrations were measured via ELISA and expressed as area under the curve (AUC). Endometrial biopsies were collected at Day 12 postovulation, RNA was isolated, and the purity and integrity were assessed before RNA sequencing. Library preparation and subsequent nucleotide sequencing were performed according to Illumina protocols (TruSeq Stranded RNAseq Sample Prep kit; Illumina, San Diego, CA, USA). The libraries were quantified by quantitative PCR and sequenced on 2 lanes for 101 cycles from each end of the fragments on a HiSEqn 2000 using a TruSeq SBS sequencing kit version 3, generating an average of 27.3 × 106 stranded 100-bp paired-end reads per sample. The raw sequences (fastq) were analysed using CLC Genomics Workbench software (version 6.0). Trimmed and filtered reads were mapped to the equine reference genome (EquCab2.0) and quantified for nucleotide coordinates corresponding to Ensembl’s consensus gene models (www.ensembl.org). Gene expression analyses were performed using an empirical analysis of digital gene expression and a false discovery rate correction. Gene functions and pathways were analysed using Ingenuity® Pathway Analysis on the differentially expressed transcripts. For the control oestrous cycle, AUC for P4 was 94.7 ± 4.3 (mean ± standard error of the mean) v. 19.6 ± 1.0 ng day–1 per mL in treated cycles (P < 0.0001). Differential expression of 623 gene loci was identified. Of these, 381 were upregulated and 242 were downregulated in the low-P4 samples. Some of the functions and canonical pathways significantly altered included cholesterol biosynthesis and lipid metabolism and activation of oestrogen mediated S-phase entry, cyclins, and cell cycle: G1/S checkpoint regulation, oxidative phosphorylation, and apoptosis signaling. In conclusion, lower concentrations of P4 during the luteal phase resulted in substantially altered gene expression and significant changes for several cell-signalling pathways in the equine endometrium. This work was supported by the Albert G. Clay Endowment and the Mellon Postdoctoral fellowship.

Postpartal immunometabolic gene network expression and function in blood neutrophils are altered in response to prepartal energy intake and postpartal intramammary inflammatory challenge

The effect of over-feeding energy prepartum on blood polymorphonuclear neutrophil (PMN) response remains unclear. Cows fed controlled (CON; 1.34Mcal/kg of dry matter) or excess energy (OVE; 1.62Mcal/kg dry matter) during the dry period (~45d before expected calving date) received an intramammary (IM) challenge with Escherichia coli lipopolysaccharide (LPS) during the postpartal period to determine the effects of IM LPS and prepartal diet on the expression of key genes associated with immunometabolic response in blood PMN. Feed intake and daily milk yield were recorded throughout the study period. At 7d in milk (DIM), all cows received LPS (200µg) into 1 rear mammary quarter. Blood PMN were isolated at 7, 14, and 30 DIM, as well as before (0h) and after (12h) IM LPS challenge for gene expression analysis using quantitative real time PCR. Phagocytosis capabilities in vitro were assessed at 7, 14, and 30 DIM. Data were analyzed using the MIXED procedure of SAS with repeated measures. No differences in feed intake and milk yield were observed between OVE- and CON-fed cows. As expected, IM LPS challenge altered the expression of genes associated with the immune response (e.g., 1.9- and 1.8-fold for SELL and TLR2, respectively), metabolism (e.g., 1.8- and -1.8-fold for LDHA and SLC2A1, respectively), and transcription (e.g., 1.1- and 1.7-fold for NCOR1 and PPARD, respectively). At 12h postchallenge, an upregulation of TLR2 (1.8-fold), HIF1A (1.9-fold), and NFKB1 (1.5-fold) was observed for OVE rather than CON. At 7 DIM, S100A9 tended (2.2-fold) to be upregulated for OVE rather than CON. At 14 DIM, OVE resulted in lower PMN phagocytosis and an upregulation of NCOR2 (1.6-fold) and RXRA (1.9-fold) compared with CON-fed cows. At 30 DIM, an upregulation of MPO (3.5-fold) and PLA2G4A (1.5-fold) and a tendency for RXRA (1.7-fold) was observed for OVE- rather than CON-fed cows. Our results suggest that IM LPS challenge altered gene expression associated with metabolism in PMN and that OVE impaired PMN phagocytosis and increased the expression of immunometabolic genes after IM LPS challenge and during the postpartal period. The current study provides new linkages among prepartal feed energy intake, metabolism, and immune response of blood PMN and risk of disease during early lactation.

Comparison of gene expression profiles of the jejunum of broilers supplemented with a yeast cell wall-derived mannan oligosaccharide versus bacitractin methylene disalicylate

1. The addition of yeast cell wall (YCW) mannan fractions or low concentrations of antibiotics to the diet of broilers positively affects gut health by improving intestinal cell morphology and improves feed efficiency and performance; however the exact mechanisms are unclear. Based on these production responses, the objective of this study was to compare the effects of supplementing YCW and bacitracin methylene disalicylate (BMD) in the diet on mRNA levels in the jejunum of 6-week-old broilers. 2. Dietary treatments were a maize-soya control diet and the control diet with the addition of YCW or BMD. Birds (n = 7) from each dietary treatment were randomly selected and killed at d 42. Whole jejunum (with serosa) samples were collected for RNA isolation. Gene expression analysis was performed using the AffymetrixGeneChip Chicken Genome Array (Santa Clara, CA, USA). 3. Supplementation with YCW resulted in 928 genes that were significantly changed (456 down-regulated, 472 up-regulated) and supplementation with BMD resulted in 857 genes that significantly changed (408 down-regulated, 449 up-regulated). In addition, 316 genes were significantly changed by both YCW and BMD (146 down-regulated, 170 up-regulated). 4. BMD increased the expression of genes involved in lipid and carbohydrate metabolism and decreased expression of genes associated with T-helper cell pathways. Gene expression profiles from birds fed on diets containing YCW showed changes on a genomic level that correspond to slower gut cell turnover and therefore increased energy preservation for growth. 5. In conclusion, supplementation with BMD or YCW had similar influences on the number of differentially expressed genes in the jejunum. Biological functions common to both YCW and BMD with positive activation scores included antiviral response and antimicrobial response. Genes that were affected by BMD or YCW classified into both different and common biological functions and pathways related to improved metabolism and health in the jejunum.

Corium tissue expression of genes associated with inflammation, oxidative stress, and keratin formation in relation to lameness in dairy cows

Objectives were to (1) determine the feasibility of performing hoof biopsies without impairing locomotion; (2) evaluate the feasibility of using biopsied tissue for quantitative PCR; and (3) compare relative gene expression among claws for several target genes. Biopsies were performed on 6 Holstein cows, yielding 4 tissue specimens per cow from front leg, right limb, and medial claw (claw position 3); rear leg, left limb, and lateral claw (claw position 5); and rear leg, right limb, medial claw (claw position 7). Cows were monitored for lameness daily for 7 d post-biopsy and then weekly for 8 wk. Histopathological analysis confirmed that tissue collected was from between the stratum corneum and dermis. Biopsied tissue was used for RNA extraction, including evaluation of yield and purity. The profile by claw position of 19 genes with key functions in cell differentiation, proliferation, inflammation, and keratin formation was assessed via quantitative reverse transcription-PCR. Other than transient disturbances in locomotion score in some cows during 2 to 4 d post-biopsy, no signs of pain, locomotion impairment, or clinical lameness were observed post-biopsy. Total RNA yields averaged 259.7±100, 447.8±288, and 496.4±118 μg/mg of tissue for claw positions 3, 5, and 7, respectively. The biopsy procedure was successful for obtaining corium for gene expression. Among 5 keratin proteins analyzed, only keratin 5 was expressed. Transcripts related to inflammation and oxidative stress (STAT3, MYD88, SOD2, and TLR4) were among the more abundant in corium tissue, but expression did not differ between claws. Biotinidase (BTD) expression was greater in claw 3 versus claw 5, whereas the ligand-activated nuclear receptor retinoic acid receptor-α (RXRA) was greater in claws 3 + 5 compared with claw 7. Overall, results from this pilot study revealed modest differences at the transcriptome level, suggesting that biotin availability and lipid metabolism differ between claw positions, whereas inflammation and oxidative stress seem to play an important role across claws. More comprehensive studies of the hoof transcriptome are required to improve our understanding of the mechanisms that link environmental and dietary factors to development of lameness.

Adipose tissue depots of Holstein cows are immune responsive: inflammatory gene expression in vitro

The transcriptional response of adipose tissue depots with respect to their immune responsiveness in dairy cows remains largely unknown. Thus, we examined mRNA expression and responsiveness of subcutaneous (SUB) and mesenteric (MES) adipose tissue from nonpregnant dairy cows to a short-term (2 h), in vitro lipopolysaccharide (LPS) challenge (20 microg/mL in physiological saline). Abundance of mRNA for tumor necrosis factor-alpha (TNFA), interleukin-6 (IL6), serum amyloid A3 (SAA3), toll-like receptor 4 (TLR4), monocyte chemoattractant protein-1 (CCL2), and RANTES/chemokine C-C motif ligand 5 (CCL5) were analyzed using quantitative polymerase chain reaction (PCR) from tissue samples collected at slaughter from 5 nonpregnant/nonlactating Holstein cows. Prior to LPS challenge, SAA3 mRNA abundance was greater in MES than SUB tissue. Regardless of depot site, LPS led to greater mRNA abundance of TNFA and IL6 and was more pronounced for IL6 in MES. We also observed a marked increased in expression of CCL2, CCL5, TLR4, IL6, and TNFA in both MES and SUB during the 2-h incubation with saline alone (ie, the control). Because mRNA expression of the apoptotic markers B-cell CLL/lymphoma 2 (BCL2) and tumor protein p53 (TP53) did not differ during the 2-h incubation, it is less likely that the response to saline was a result of increased rate of cell death during incubation. Analysis using semiquantitative PCR of the 16s rRNA gene in cDNA from tissue explants revealed the presence of bacteria likely arising from contamination during sample collection. Furthermore, surfactant medium from about 50% of explant cultures had viable aerobic bacteria without differences between treatments or tissue samples. Thus, the presence of bacteria could partly explain the large increase in inflammatory-related genes after 2-h incubation with saline. The higher SAA3 expression in MES suggests that this acute-phase protein has a role in lipid metabolism and/or transport during an immune challenge. Overall, results provided evidence that adipose depots of dairy cows are capable of synthesizing chemokines and are immune responsive when exposed to inflammatory conditions that can arise from a pathogenic insult or during and soon after parturition.

Internal controls for quantitative polymerase chain reaction of swine mammary glands during pregnancy and lactation

High-throughput microarray analysis is an efficient means of obtaining a genome-wide view of transcript profiles across physiological states. However, quantitative PCR (qPCR) remains the chosen method for high-precision mRNA abundance analysis. Essential for reliability of qPCR data is normalization using appropriate internal control genes (ICG), which is now, more than ever before, a fundamental step for accurate gene expression profiling. We mined mammary tissue microarray data on >13,000 genes at -34, -14, 0, 7, 14, 21, and 28 d relative to parturition in 27 crossbred primiparous gilts to identify suitable ICG. Initial analysis revealed TBK1, PCSK2, PTBP1, API5, VAPB, QTRT1, TRIM41, TMEM24, PPP2R5B, and AP1S1 as the most stable genes (sample/reference = 1 +/- 0.2). We also included 9 genes previously identified as ICG in bovine mammary tissue. Gene network analysis of the 19 genes identified AP1S1, API5, MTG1, VAPB, TRIM41, MRPL39, and RPS15A as having no known co-regulation. In addition, UXT and ACTB were added to this list, and mRNA abundance of these 9 genes was measured by qPCR. Expression of all 9 of these genes was decreased markedly during lactation. In a previous study with bovine mammary tissue, mRNA of stably expressed genes decreased during lactation due to a dilution effect brought about by large increases in expression of highly abundant genes. To verify this effect, highly abundant mammary genes such as CSN1S2, SCD, FABP3, and LTF were evaluated by qPCR. The tested ICG had a negative correlation with these genes, demonstrating a dilution effect in the porcine mammary tissue. Gene stability analysis identified API5, VABP, and MRPL39 as the most stable ICG in porcine mammary tissue and indicated that the use of those 3 genes was most appropriate for calculating a normalization factor. Overall, results underscore the importance of proper validation of internal controls for qPCR and highlight the limitations of using absence of time effects as the criteria for selection of appropriate ICG. Further, we showed that use of the same ICG from one organism might not be suitable for qPCR normalization in other species.