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Nucleotide-rich yeast extract (YN) was investigated for effects on growth performance, jejunal physiology, and cecal microbial activity in Eimeria-challenged broiler chickens. A total of 360-day-old male chicks (Ross × Ross 708) were placed on floor pens and provided a corn–soybean meal-based diet without or with YN (500 g/MT; n = 12). On d 10, 6 replicates per diet were orally administered with 1 mL of E. acervulina and E. maxima sporulated oocysts and the rest (non-challenged control) were administered with 1 mL of distilled water. On d 15, 5 birds/pen were then necropsied for intestinal lesion scores, histomorphology and cecal digesta pH, short chain fatty acids (SCFA), and microbial community using Illumina Miseq platform. Supplemental YN improved (P = 0.01) Feed conversion ratio (FCR) during the prechallenge phase (d 0 to 10). In the postchallenge period (d 11 to 15), Eimeria depressed (P < 0.05) Body weight gain (BWG) relative to non-challenged birds, whereas YN-fed birds had a higher (P = 0.05) BWG compared to that of non-YN-fed birds. There was an interaction between YN and Eimeria on jejunal villi height (VH) (P = 0.001) and expression of cationic amino acid transporter 1(CAT1) (P = 0.04). Specifically, in the absence of Eimeria, YN-fed birds had a shorter VH (892 vs. 1,020 μm) relative to that of control but longer VH (533 vs. 447 μm) in the presence of Eimeria. With respect to CAT1, YN-fed birds had a higher (1.65 vs. 0.78) expression when subjected to Eimeria than when not challenged. Independently, Eimeria decreased (P < 0.01) the jejunal expression of maltase, Na glucose transporter 1 and occludin genes, ceca digesta abundance of genus Clostridium cluster XlVa and Oscillibacter but increased (P < 0.01) jejunal proliferating cell nuclear antigen and interleukin 10. Interaction between YN and Eimeria was observed for ceca digesta pH (P = 0.04) and total SCFA (P = 0.01) such that YN increased SCFA in the absence of Eimeria but reduced SCFA and increased pH in the presence of Eimeria. In summary, Eimeria impaired performance and gut function and shifted gut microbiome; YN improved performance independently, attenuated Eimeria damage on indices of gut function, and modulated cecal microbiome.

Breeding stress-resilient livestock is a potential strategy to help mitigate the negative effect of environmental and pathogenic stressors. The hypothalamic-pituitary-adrenal axis and immune system are activated during stress events and release mediators into the circulation that help restore physiological homeostasis. The purpose of this study was to assess a comprehensive set of circulatory mediators released in response to an acute immune stress challenge to identify candidate biomarkers that can be used for the selection of stress-resilient animals. Fifteen female lambs were stress challenged with an intravenous bolus of lipopolysaccharide (LPS; 400 ng/kg), and blood was collected from the jugular vein at 0, 2, 4, and 6 h after LPS challenge to identify and monitor candidate stress biomarkers; temperature was also recorded over time. Biomarker responses were evaluated with a repeated-measures model to compare time points with baseline values. As expected, all sheep had a monophasic febrile response to LPS challenge, and cortisol increased and returned to baseline by 6 h. The cytokines tumor necrosis factor-α, IL-6, IFN-γ (proinflammatory), and IL-10 (anti-inflammatory) increased, but only tumor necrosis factor-α returned to baseline during the monitoring period. The cytokines IL-1α, IL-1β, IL-17α (proinflammatory), and IL-4 (anti-inflammatory) did not respond to LPS challenge. All chemokines (CCL2, CCL3, CCL4, CXCL10, and IL-8) responded to LPS challenge; however, only CCL2, CCL3, CCL4, and CXCL10 increased over time, and only CCL3, CCL4, and CXCL10 returned to baseline during the monitoring period. MicroRNA (miR-145, miR-233, and miR-1246) also increased and remained elevated during the study. In summary, the LPS challenge induced a strong stress response in Rideau-Dorset sheep that could be monitored with a distinct profile of circulatory biomarkers.

Dairy producers disbudding calves with caustic paste are less likely to provide pain control than those using cautery. Little research has been conducted on pain control for this method and no studies have speifically examined calves under a week of age although producers will commonly apply this product at this time. The objective of this study was to evaluate the efficacy of local anesthesia and nonsteroidal anti-inflammatory drug (NSAID) analgesia in very young dairy calves disbudded with caustic paste., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2019

Adverse uterine environments experienced during fetal development can alter the projected growth pattern of various organs and systems of the body, leaving the offspring at an increased risk of metabolic disease. The thrifty phenotype hypothesis has been demonstrated as an alteration to the growth trajectory to improve the survival and reproductive fitness of the individual. However, when the intrauterine environment does not match the extrauterine environment problems can arise. With the increase in metabolic diseases in both Westernized and developing countries, it is becoming apparent that there is an environmental disconnect with the extrauterine environment. Therefore, the focus of this paper will be to explore the effects of maternal malnutrition on the offspring’s susceptibility to metabolic disorders such as obesity, cardiovascular disease, and diabetes with emphasis on programming of the neuroendocrine-immune system.

The major histocompatibility complex (MHC) class I and class II molecules bind selectively to different antigenic peptides and present peptides to T-cell receptors. In mice and humans, peptide binding affinity (low and high) to MHC II molecules influences T-helper 1/T-helper 2 responses by inducing distinctive cytokine expression. To examine the effects of peptide binding affinity to bovine MHC, the BoLA-DRB3*2703 allele, previously associated with mastitis in Canadian Holsteins, was extracted and purified from BoLA-DRB3*2703-transfected L929 cells. Self peptides (BoLA-DQ and bovine fibrinogen fragments) previously eluted from this allele and non-self peptides from the core region of ovalbumin (OVA), as well as VP2 and VP4 peptides from foot and mouth disease virus (FMDV) were used in competitive binding assays. Briefly, a self-peptide of BoLA-DQ with high binding affinity was biotinylated as the marker peptide to use in competitive binding with purified BoLA-DRB3*2703 molecules in the presence of various concentrations of competing peptides. Binding was detected using Western blotting and enhanced chemiluminescence. Binding affinity determined as IC50 (concentration of competing peptides required to inhibit 50% binding), ranged from 26 to >320 :M. Two OVA peptides (OVA 323-335, OVA 323-339) and one FMDV peptide (VP-4) bound with relatively high affinity; 26.92, 72.22 and 46.46 :M respectively. OVA peptides, 316-327 and 325-336, bound weakly (>320 :M) to BoLA-DRB3*2703, while OVA 322-332 and VP-2 did not bind to this allele. Presence of glutamic acid, isoleucine, and asparagine at positions 333-335 appeared to partly influence peptide binding, but accurate prediction of binding will require computer scoring algorithms to scan protein sources of putative peptide ligands. Additionally, T-cells from a BoLA-DRB3*2703 homozygous cow were stimulated in vitro and cell proliferation was determined using the above peptides and transfected L929 cells as antigen presenting cells. OVA peptides, but not VP-4, with high binding affinities were able to induce significant T-cell proliferation. T-cell cytokine (IFN-3 and IL-4) production following stimulation with these peptides is currently under investigation. (Texte intégral)

An immune response (IR) index to identify dairy cows with high (H) and low (L) antibody-mediated immune responses (AMIR) had been previously devised. High AMIR associated with decreased mastitis and improved response to vaccination. Measurement of cell-mediated immune response (CMIR) was not included in the index; therefore various antigen/adjuvant combinations were evaluated as inducers of DTH as indicators of CMIR to be added to the IR-index. The Bacillus Calmette Guèrin (BCG) induced/purified protein derivative (PPD) ellicited tuberculin skin test is a reliable measure of DTH; however, its use to identify livestock with high CMIR may be confounded due to previous exposure to Mycobacteria tuberculosis. DTH to BCG/PPD was therefore compared with that induced by Mycobacteria phlei (a saprophyte) and its derivative phlein as the test antigen. Adjuvants tested included Freund=s Complete Adjuvant (FCA), non-ulcerative Freund=s adjuvant (NUFA), complete NUFA and Mycobacteria phlei cell wall extract (MCWE). Reaction to PHA mitogen was also evaluated. Experimentally induced antibody response to OVA was evaluated with DTH in each treatment group of 5 cows. Results indicated that BCG/PPD and M. phlei/phlein treatments induced similar DTH with peak reactions at - 48 hours after intradermal antigen injection and that there was substantial variation in DTH between cows. Antibody response to OVA was also similar. Cows could be ranked for both AMIR and CMIR. The NUFA and MCWE treatments induced fewer granulomas than FCA or cNUFA. The change in skin thickness response to PHA peaked at 6 hours, had leukocyte infiltration similar to other treatments, but significantly fewer lymphocytes, based on skin biopsies taken from DTH test sites. It was generally concluded that M. phlei/phlein and BCG/PPD induced similar DTH, but that cross reaction to PPD was evident following induction of DTH using M. phlei making it a less than ideal alternative for testing livestock. To detect possible genetic differences between H and L, RNA from blood lymphocytes of cows with the highest and lowest IR ranks above were reverse transcribed. Typically, 8-10 :g of Qiagen purified total RNA was used in a 40:1 RT reaction volume. RNA from H and L cows were fluorescently labeled with different colour fluors (Cyanine 3 and 5). Each 40:1 labeling reaction generated sufficient cDNA to probe 1 array. A Human 1.7kD microarray (Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ca) containing 1700 known genes was utilized. Initial results indicate that the expression of over 200 genes, including, STAT1, natural killer cell enhancing factor A, cathepsin S precursor, leukocyte surface antigen CD53, immunoglobulin J chain, and zinc finger proteins, differ between H and L. Evaluation of a larger number of cattle classified as H or L immune responders is required to construct accurate genetic profiles. (Texte intégral)