2011 Annual Report
1a.Objectives (from AD-416)
Objective 1: Identify physiological, immunological, endocrinological and gastrointestinal-microbiological alterations which occur in infected livestock when subjected to common managerial stressors.
Objective 2: Understand how handling and transportation stress influence livestock pathogens, such as, Salmonella and Campylobacter, which have the potential to detrimentally affect human health.
1b.Approach (from AD-416)
We will subject livestock to both mixing and transportation and collect behavioral, physiologic, immunologic, endocrine, and bacterial data. The behavior data will include: agonistic encounters, loss of balance, vomiting, standing, lying, stereotypic behavior, and any other abnormal behaviors (i.e. shaking, jumping, etc). The physiologic, immunologic, and endocrine data will include: heart rate, body temperature, cortisol, epinephrine, norepinephrine, dopamine, immune cell populations, interferon-gamma, interleukin-1, interleukin-12, haptoglobin, alpha 1-acid glycoprotien, and immunoglobulins. The bacterial data will include: DGGE pattern, total aerobes, anaerobes, Enterobacteriaceae counts, and the proportion of antimicrobial resistant Enterobacteriaceae in different compartments of the gastrointestinal tract and in mesenteric lymph nodes. Analysis of these collective data will allow for identification of key processes that create high pathogen loads at slaughter plants.
Our approach is a strategy that will.
1)use a novel technique to monitor the progression of infection of stressed swine,.
2)study the influence of mammalian stress hormones on bacteria, and.
3)determine physiologically how a dietary supplement can impair bacterial infection. All three of these approaches will provide novel information on how stress influences bacterial pathogens.
An in vitro study was completed in which host specific and two non-host specific Salmonella were used to stimulate leukocytes (white blood cells) of calves. We determined that calf cells respond differently to the host-specific Salmonella than they do to the non-host specific Salmonella. This study is completed and a manuscript has been submitted. These data were used for an abstract submitted to the Conference of Research Workers in Animal Diseases. A replication of the heat stress study performed in HI in the previous project is underway in IN. In this study, we aim to determine if the environment or innate immunity is compromised of the calf born after a heat stress event in confinement dairies. Animals have been identified that fit the criterion for the experiment and the experiment has been initiated. A study is underway that evaluates the effects of exogenous dietary enzymes on gut microbes in young pigs. Additionally, to transition to NP101, a preliminary project is in progress for the upcoming year to utilize the bacteriostatic properties of cranberry pomace to alleviate bacterial load on piglets during weaning as we migrate toward studies using neonatal and weaned piglets, and defining the development of the intestinal population and associated immunity.
Host-pathogen interactions of Salmonella in dairy calves. The progression of disease for host-specific types of Salmonella is typically more systemic than non-host specific types, but the mechanisms are not clear. ARS researchers at West Lafayette, Indiana, stimulated calf leukocytes (white blood cells) in the lab with one cattle host-specific type (Salmonella Dublin) and two types that are not host-specific for cattle (Salmonella Enterica and Salmonella Typhimurium). A cell recruiting molecule (Interleukin-8) and a molecule(CD14) involved in recognition and attachment of pathogens were greater for cells that were exposed to Salmonella Dublin (the host-specific type). In contrast, the killing of bacteria by the calves’ cells was suppressed by adding antibody to S. Dublin. These data show that S. Dublin enters a specific cell population (monocytes) more readily and that early stimulation mechanisms occur, but killing of the bacteria is suppressed. This allows the bacteria to survive in the cell and be delivered to other parts of the body by traveling in the cell. Therefore, treatment methods need to be different for the host-specific types which appear to invade and suppress immune cells compared with non-host specific types which did not suppress the immune cells.