The Athens Canadian Random Bred (ACRB) heritage broiler breed, which has not been selectively bred since the 1950s, is a point of comparison to the modern-day broiler and could highlight potential genetic-derived differences in immune responses. To observe the modern and heritage birds’ immune responses in action, the innate immune ligand CpG oligonucleotides were administered at multiple time points through the birds’ lives from the day after hatch to day 35 post-hatch. This study allowed for the observation of changes in metabolic and immune signaling in response to repeated injections of a known Toll-like receptor (TLR) ligand, CpG. Jejunum and cecal tonsil samples at multiple time points during grow out were collected and used for kinome array analysis to measure kinase activity in immunometabolic signaling pathways in the gut tissue. In addition cytokine gene expression was measured in these tissues. The modern birds’ response to the treatment was more innate and showed evidence of metabolic energy shift. The heritage birds’ response to the treatment was adaptive, with metabolic changes indicative of a well-regulated response. Overall, the results from this study suggest that modern broiler chickens do not adequately balance resources between growth and immune responses during an immune challenge, and this deficit is most evident around the 2-week post-hatch time point. This is a critical time for these birds, as their muscle deposition continues to accelerate, and they are vulnerable to disease challenges. Ideally, future work can clarify the reason for this response discrepancy in the modern broiler and therapeutic interventions to rescue this phenotype could be elucidated.

Inducing inflammation in response to pathogen infection is known to be an energy-intensive process. An extended state of inflammation in production animals can be detrimental to performance parameters. Here, we compare two doses of a microencapsulated thymol-based feed additive blend and two different antibiotics in the context of a Salmonella Enterica subsp. Enterica serovar Enteritidis (SE) challenge. A total of 500, day-old, straight run chicks (Ross 708) were placed in floor pens (50 chicks/pen) and assigned to 5 groups with 2 replicates each. The groups were all fed with basal diets, without supplementation (Control) or supplemented with: tylosin at 25 g/MT (Tylosin); neomycin sulfate at 100 g/MT (Neomycin); or a microencapsulated thymol-based blend of botanicals at inclusions of 500 g/MT (Blend 500) or 1000 g/MT (Blend 1000). All the pens were orally challenged at day 4 with SE at 10⁵ CFU/bird. At 7, 14, 21, and 35-days post hatch, ten animals from each pen were weighed and euthanized in order to culture enumerate SE in the ceca and determine SE prevalence in the liver. Gene based prevalence, gene expression, and kinome analysis were performed on jejunum samples collected at day 35. The higher dose of the tested botanical, Blend 1000, showed a statistically significant increase in final body weight relative to the other groups, indicating an energy benefit for this group. The Blend 1000 also showed a reduction in protein phosphorylation that corresponds to reduced inflammatory status that was unique compared to Blend 500 and the antibiotics. These birds also showed a clearance of orally inoculated SE demonstrating that reduced inflammation can benefit the broiler chicken in clearance of bacteria while maintaining growth.

Salmonella in gut habitats have traditionally been thought to conserve energy for growth via fermentation. However, recent reports indicate that ingested Salmonella can stimulate host-derived nitrate accumulation in the mucosal microenvironment, thereby enabling growth through nitrate respiration. Sodium tungstate is an effective treatment that inhibits the growth of certain nitrate-respiring bacteria, including Escherichia coli, Paracoccus and Proteus, when cultured under gut simulating conditions or within the gut of experimentally treated mice. This inhibitory effect is hypothesized to occur by inactivation of molybdenum-containing enzymes required for nitrate metabolism. Information is lacking on whether tungstate can inhibit the growth of Salmonella, particularly in the presence of culturable gut microbiota. Therefore, the objectives of this study were to evaluate the effects of sodium tungstate on Salmonella during pure culture or when cultured with freshly collected bovine rumen microbiota and to assess its impact on fermentation as well as nitrate and nitrite metabolism within the rumen microbial cultures. Our results indicate that 50 mM sodium tungstate treatment, whether alone or in combination with 5 mM nitrate, markedly increased the growth of Salmonella serovars Newport, Dublin and Typhimurium during pure culture. Moreover, during in vitro incubation, increased growth of experimentally inoculated S. Newport as well as wildtype E. coli and lactic acid bacteria was observed with ruminal microbiota treated with 100 mM tungstate when compared to non-tungstate-treated controls. Effects of tungstate on nitrate and nitrite metabolism were as expected during pure and mixed culture. When cultured with reduced tungsten rather than tungstate, the latter being bound to four oxygen atoms, an inhibitory effect on the growth of S. Newport was observed and effects on nitrate and nitrite metabolism were consistent with those observed with tungstate. These results suggest that, under conditions used in the present experiments, tungstate may have served as a source of oxygen for respiration above that achieved with nitrate alone. While this hypothesis has yet to be proven, it is supported by an adverse effect of tungstate, whether alone or in combination with 5 mM nitrate, on methane and volatile fatty acid production by the ruminal microbiota when compared to untreated or nitrate-only-treated microbiota.

While the genetic similarities between vertebrates have been remarked on with each new complete genome sequenced, the physiological and phenotypic differences between agricultural species remain clear even to the casual observer. As one moves along the path of molecular biology, from DNA to RNA to protein, the distinctions between species increase. The separation between species further increases when the active sites of protein are considered. Phenotype is dictated by gene expression patterns, response to environmental stimuli, epigenetic alterations, protein translation, protein folding and interactions, post-translational modifications, and a host of other mechanisms. Post-translational modifications that mediate cellular signaling cascades and cellular response to stimuli are predominantly facilitated by protein kinases. Studying the changes in protein kinase activity is as close as we can come to studying phenotype and remain at a molecular level. Intracellular metabolic responses, specifically, depend on these kinase switches and are often transcriptionally independent; an organism must respond to the availability of nutrients and does not have time to engage the transcription and translation machinery to take up and consume sources of energy. Meanwhile the immune system often initiates responses through gene expression changes. Thus, studying kinase activity allows us to study metabolism alongside gene expression dependent responses such as most immune responses. Over many years of studying poultry in the context of foodborne pathogens, especially Salmonella species, a few kinase dependent pathways and energy sensors have emerged as critical to resistance or susceptibility. The central immunometabolic signaling hubs, such as PI3K-AKT-mTOR, have been shown to be part of the immunometabolic physiological responses key to resistance or susceptibility in chickens. Salmonella infections have a significant impact on kinases in these signaling hubs, while the most promising interventions modulate these hubs. Directing breeding selection criteria or feed additive interventions to these hubs and critical activating/deactivating control points is a promising approach in controlling these foodborne pathogens in poultry.