2009 Annual Report
1a.Objectives (from AD-416)
The long-term objective of this project is to enhance animal well-being and performance in swine and beef industry production environments. Over the next 5 years we will focus on the following objectives:
Objective 1: Identify non-antibiotic nutritional supplements that support and/or enhance immune function in weaned pigs and incoming feedlot cattle.
Objective 2: Determine the relationships among animal temperament, stress responsiveness, and immune function in cattle as related to livestock management practices, such as weaning and transportation, and utilize this information to develop alternative management practices that enhance immunity, productivity, and overall well-being.
1b.Approach (from AD-416)
Our research will focus on enhancing well-being and performance in beef and swine during periods of production known to be stressful. For Sub-objective 1A, several experiments will be conducted to evaluate various parameters associated with the well-being and productivity of swine challenged with Salmonella Typhimurium following dietary inclusion of either sub-therapeutic levels of antibiotics or various nutritional supplements. Blood samples will be collected for analysis of hormones associated with the stress response, as well as hormones associated with function of the somatotropic axis. Animals will be videotaped to evaluate various sickness behaviors. For Sub-objective 1B, cross-bred beef calves will be weaned at approximately 6 months of age and fed various non-antibiotic products as potential modulators of immunity. Calves will be provided either a medicated diet or a non-medicated concentrate ration containing a non-antibiotic supplement for 21 days. Calves will be inoculated with infectious bovine rhinotracheitis virus (IBRV) to determine if the non-antibiotic supplements provided any immunological protection. Feed intake and body weight will be determined weekly. Blood samples will be collected for analysis of hormones associated with the stress response, the growth response, as well as cytokines and acute phase proteins associated with the immune response. For Objective 2, we will focus initially on validation of an automated tracking system using the 'color' tracking method. Once this validation is complete, the ‘color’ tracking will be used to document the behavior of individual pigs following a Salmonella Typhimurium challenge. Pigs will be video recorded over a 5-day period to determine if the infected pig’s behavior can be distinguished from that of the non-infected pigs. Subsequent transmission and infection in other pigs will be monitored by testing for the presence of the bacteria in fecal samples. For Objective 3, the research will be divided into two separate studies. The first study will address the potential effect of temperament on the innate immune response, and the second study will address the potential effect of temperament on adaptive immunity. In both studies, weaning-age calves from a single breed type will be categorized as to their temperament (temperamental or calm) based upon an objective exit velocity (EV) scoring system. Exit velocities will be obtained by determining the rate at which calves exit the working chute and traverse a fixed distance (1.83 m). In Study 1, we will assess the innate immune response to an endotoxin challenge based upon temperament. Blood samples will be collected and serum analyzed for hormones associated with the stress response, as well as cytokines associated with the acute phase immune response following the LPS challenge. In Study 2, we will assess the adaptive immune response following inoculation with IBRV. Body weights, blood samples, and rectal temperatures will be collected post-challenge. Blood samples will be collected for analysis of hormones associated with the stress response, as well as cytokines associated with the adaptive immune response.
Scientists at the Livestock Issues Research Unit were involved in 8 collaborative research projects during FY2009, primarily associated with our project objectives 1A and 3. Specifically, associated with Sub-objective 1A, a collaborative study was conducted to evaluate a live yeast product on the innate immune response of weanling pigs to an endotoxin challenge. The data indicated that providing a live yeast product significantly decreased the mortality rate associated with the endotoxin challenge and altered important indices associated with the acute phase immune response. A second study evaluated the inclusion of orange peel/pulp byproduct in weaned pig diets as a means to reduce the detrimental effects associated with a live bacterial challenge. Data analysis on this study is forthcoming and should allow us to further refine our research direction with regard to this sub-objective. For Sub-Objective 1B, a collaborative study was conducted to elucidate the innate immune response associated with a viral challenge model in beef calves. The intent of this research was to define the most appropriate sampling period to evaluate differential responses to a viral challenge in beef calves based upon potential dietary modulation of this response. Data from this preliminary study warrants a reevaluation of our challenge model, and data analysis is forthcoming that will allow us to refine this model for future research projects. We are currently evaluating the first supplement as an immune system modulator in beef calves and have opted to utilize an endotoxin challenge in this first study due to the results obtained in our viral challenge studies. Completion of these two studies will allow us to fully meet our outlined milestones for FY2009. For Objective 2, an initial study was conducted to monitor weanling pig behavior following a live pathogen challenge. The results of this study highlighted the need for continued refinement of this process and provided valuable information that will be essential in the overall success of this research effort. Therefore, while we did meet our milestone for the year, the study highlighted important issues that need to be addressed before moving forward with this research. Associated with Objective 3, we continued with several collaborative efforts designed to evaluate the influence of temperament on the innate immune response in beef cattle. Coupled with this research endeavor, we also evaluated the influence of temperament on the animal's response to transportation, and also evaluated the potential for a sexually dimorphic innate immune response. To date, we have successfully profiled the proinflammatory cytokine response, the febrile response and sexually dimorphic immune responses in beef cattle associated with an endotoxin challenge. Additionally, with regard to the transportation studies, the data indicates that transportation is not as stressful as once thought, and other factors, such as handling, may significantly influence parameters typically used to identify stress responses in cattle.
Is transportation really stressful to cattle? A common perception is that transport of livestock for extensive periods is a stressful experience. Scientists from the Livestock Issues Research Unit in Lubbock, Texas, in collaboration with scientists from Texas A&M AgriLife and Mississippi State University had the insight to separate transportation into processing and handling phase and the movement phase. Their studies indicate that transportation for 8 hours is not a significant stressor in cattle. In fact, the data indicate that the processing and handling of cattle prior to being loaded on a trailer may be the major stressful aspect of the transportation process. This research will lead to a better understanding of the production components that are truly stressful to livestock, and is essential information needed to develop alternative management practices to improve livestock well-being.
Sex linked to the stress response and immune function in beef calves. Understanding health risk factors for cattle will enable more effective and efficient livestock management. Scientists within the Livestock Issues Research Unit in Lubbock, Texas, in collaboration with scientists from Texas A&M AgriLife and Mississippi State University, conducted an intensive study to determine if sex would influence how the animals responded to an immune challenge. This study clearly demonstrated that purebred Brahman bull and heifer calves respond differently to an immune challenge; heifer calves recovered more quickly than bull calves. These data demonstrate that sex may be an important factor for managing cattle health, productivity and well-being.
Feeding live yeast reduces death losses in young pigs. There is an increasing demand for and interest in alternatives to sub-therapeutic antibiotics in livestock production due to concerns over increased incidence of antibiotic-resistant pathogens. Collaborative studies by scientists from the Livestock Issues Research Unit in Lubbock, Texas, and the Canadian-based yeast company, Lallemand, Inc., demonstrated that supplementing the weaned pig's diet with a live yeast product for 14 days prior to being exposed to a bacterial challenge reduced the incidence of mortality and altered the innate immune response. Identifying alternatives to sub-therapeutic levels of antibiotics for inclusion in livestock feeds is an essential step towards securing the sustainability of livestock production in the U.S.