Location: Livestock Issues Research2010 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 the performance, health, and overall well-being of beef cattle and swine in production environments. For the swine studies in Objective 1, several experiments will be conducted to evaluate various parameters associated with the health and productivity of swine following dietary inclusion of various nutritional supplements that have the potential to enhance innate immunity. Blood samples will be collected for analysis of hormones associated with the stress response, as well as hormones associated with the proinflammatory response following an endotoxin challenge. For cattle studies in Objective 1, 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 either inoculated with infectious bovine rhinotracheitis virus (IBRV) to determine if the non-antibiotic supplements provided any immunological protection to a viral challenge, or exposed to endotoxin to evaluate whether or not these non-antibiotic supplements enhance innate immunity. Feed intake and body weight will be routine measurements. Blood samples will be collected for analysis of hormones associated with the stress response, the growth axis, as well as cytokines and acute phase proteins associated with the immune response. For Objective 2, the research will focus on determining the relationships among animal temperament, stress responsiveness, and immune function in cattle as they relate to livestock management practices such as weaning and transportation. This information will be used to develop alternative management practices that enhance immunity, productivity, and overall well-being. Initial studies will determine the effect of animal temperament on the innate immune response following an endotoxin challenge. Subsequent studies will evaluate the effect of temperament on the response to management practices such as transportation. We will also evaluate the effects of weaning strategies on the innate immune system of beef calves. In these studies, weaning-age calves from a single breed 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 the first studies, 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 endotoxin challenge. In the subsequent studies, we will assess the stress responsiveness following management practices such as transportation and weaning. Body weights, blood samples, and rectal temperatures will be routine parameters measured for these studies. Blood samples will be analyzed for stress hormones, as well as cytokines associated with the immune response.
3. Progress Report
Scientists within the Livestock Issues Research Unit were involved in six collaborative research projects during FY2010 that were associated with our project objectives. For Sub-Objective 1A, a study was conducted to evaluate the inclusion of orange peel/pulp byproduct in weaned pig diets as a means to reduce the detrimental effects associated with exposure to E. coli F18. Results from this study demonstrated that feeding a diet that contained 10% citrus pulp for 13 days completely reduced the incidence of fecal shedding of E. coli. Given the increased demand for and interest in alternatives to sub-therapeutic antibiotics in livestock production, the significance of this research was recognized by the scientific community and awarded the National Pork Board Research Innovation Award at the 2010 American Society of Animal Science Southern Section Meeting. For Sub-Objective 1B, a study was conducted to evaluate the effect of feeding live yeast, Saccharomyces cerevisiae, and/or its cell wall, to high-risk cattle coming into a feedlot. Results from this study demonstrated that supplementing the diet of incoming feedlot cattle with Saccharomyces cerevisiae for a period of 39 days not only improved the health of the cattle, but also improved their ability to combat an acute exposure to an endotoxin derived from E. coli. This study also demonstrated that inclusion of this yeast altered the microbiota in a manner that may be more conducive to beneficial bacteria. These studies have resulted in significant progress towards identifying alternatives to sub-therapeutic levels of antibiotics for inclusion in livestock feeds, which is an essential step towards securing the sustainability of livestock production in the U.S. For Objective 2, collaborative studies continued towards developing an appropriate live challenge model to evaluate the adaptive immunity in beef cattle, as well as studies directed at determining the relationships among animal temperament, stress responsiveness, and immune function in cattle. For the adaptive immunity research, two collaborative studies were conducted to evaluate the immune response to an infectious bovine rhinotracheitis viral challenge and to a mannheimia bacterial challenge. These studies provided significant information regarding the physiological and immune responses in cattle following these immune challenges. Continued research will utilize these models to evaluate the use of non-antibiotic alternatives to provide immune protection in beef cattle. For the animal temperament aspect of this objective, we demonstrated that calm and temperamental cattle have distinct physiological and immunological responses that may be linked to the previous studies demonstrating distinct stress responses in these animals. Results from these studies have provided essential information needed in order to develop alternative management practices to improve livestock production, health, and overall well-being.
1. Oranges, more than a vitamin C source for young pigs. There is an increasing demand for and interest in alternatives to feeding low levels of antibiotics in livestock production systems due to concerns over increased incidences of antibiotic-resistant pathogens. In fact, there has been a recent call for voluntary elimination of the use of low level antibiotics in livestock production in the U.S. A collaborative study by scientists from the Livestock Issues Research Unit in Lubbock, Texas, and the Food and Feed Safety Research Unit in College Station, Texas, demonstrated that feeding a diet that contained 10% citrus pulp for 13 days eliminated the presence of E. coli in the feces of pigs. Supplementation of citrus pulp could potentially be used to enhance growth in weaned pigs by suppressing chronic and acute pathogenic challenges without the use of low levels of antibiotics. Identifying alternatives to antibiotics for inclusion in livestock feeds is an essential step towards securing the sustainability of livestock production in the U.S.
2. Yeast, not just for baking anymore. As with other livestock production systems, there is an increasing concern over the potential link between feeding low levels of antibiotics in cattle feedlots and the incidence of antibiotic-resistant bacteria that affect human health. In an effort to identify potential alternatives to antibiotics, scientists from the Livestock Issues Research Unit in Lubbock, Texas, teamed up with scientists from Texas Tech University and Lesaffre Feed Additives, Milwaukee, Wisconsin, to evaluate the effect of feeding the cell wall of yeast to feedlot cattle that are at a higher risk for becoming sick. The researchers demonstrated that supplementing the diet of incoming feedlot cattle with Saccharomyces cerevisiae and/or its cell wall not only improved the health of the cattle, but also improved their ability to combat exposure to the toxin from E. coli bacteria. Additionally, inclusion of this yeast altered the population of bacteria species within the intestine in a manner that suggested that the yeast may have caused an increase in beneficial bacteria. Identifying alternatives to low levels of antibiotics for inclusion in livestock feeds is an essential step towards securing the sustainability of livestock production in the U.S.
3. Not growing? Could it be a viral thing? Scientists have known for many years that sick animals don't grow to their full potential. In a collaborative study with scientists from the Livestock Issues Research Unit in Lubbock, Texas, and Mississippi State University, researchers demonstrated that even a relatively mild infectious bovine rhinotracheitis viral challenge in beef steers alters the growth hormones in these animals. In fact, the study revealed alterations in the hormones that control growth, even in the absence of detectable increases in the blood of chemical messengers that are associated with regulation of the immune system. Therefore, it appears that even a mild viral infection can have significant impact on the potential growth and performance of cattle.
4. What does fat have to do with it? In a collaborative study with scientists from the Livestock Issues Research Unit in Lubbock, Texas, and Mississippi State University, researchers demonstrated that the amount of intramuscular fat, fat located between muscles, may affect the immune response of cattle. In this particular study, the researchers evaluated the ability of Angus heifers from Mississippi State University that had been genetically selected for high and low levels of intramuscular fat deposits to combat the unfavorable effects from a toxin produced from E. coli bacteria. The study revealed that heifers lacking the genetic markers for intramuscular fat deposition had an altered immune response compared to those heifers that had a greater number of genetic markers for intramuscular fat deposition. While it is still a bit premature to determine the overall impact of this research, there does indeed appear to be a link between the amount of intramuscular fat and an animal's ability to mount an immune response.
5. Bad attitude? Maybe that’s not all bad! For several years scientists from Texas A&M AgriLife and Mississippi State University have been investigating the influence of cattle temperament on various production parameters and stress responses. More recently, scientists from the Livestock Issues Research Unit in Lubbock, Texas, have joined this collaborative effort to determine if an animal's temperament influenced its ability to handle management practices such as being transported, or its ability to cope with a bacterial infection. These studies have clearly indicated that calm and temperamental cattle have distinct physiological and immunological responses. Interestingly, the temperamental cattle seem to be more resistant to a toxin produced by E. coli bacteria, displaying less sign of clinical illness and recovering more rapidly. While handling temperamental cattle in production systems poses various challenges, there are clearly beneficial characteristics of these animals that could possibly be exploited to improve disease resistance and the associated morbidity and mortality that are significant economic burdens for the beef industry. This research will undoubtedly lead to a better understanding of variations in beef cattle production and will be essential information needed to develop alternative management practices to improve livestock production, health, and overall well-being.
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