Location: Livestock Issues Research2012 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:
Livestock Issues Research Unit scientists conducted five studies associated with the project objectives during FY12. For Sub-objective 1B, three final studies were conducted to evaluate non-antibiotic supplements as a means to enhance health and performance in beef cattle. The first study evaluated the health and performance benefits of adding citrus pulp in the diets of cattle. Results demonstrated that including citrus pulp in the diet can alter the physiological and acute phase response of newly received feedlot heifers to an immune challenge. However, inclusion of citrus pulp at levels of 10% or greater may hinder feedlot performance. The second study evaluated the inclusion of yeast cell wall in the diet of feedlot heifers. Results revealed that adding yeast cell wall in the diet of feedlot heifers reduced the negative effects associated with an immune challenge, and enhanced energy metabolism during the immune challenge. Addition of yeast cell wall to the diet also appeared to enhance performance, especially during periods of heat stress. The third study evaluated a commercially available feed additive (i.e., OmniGen-AF) typically used to treat hemorrhagic bowel syndrome in dairy cattle as a potential immune enhancer in beef calves. Results indicated that OmniGen-AF primed the immune system of the calves in a manner that expedited the recovery from an immune challenge. The data also indicated that OmniGen-AF altered the metabolic response during the immune challenge by increasing available glucose and reducing the need to mobilize energy via tissue breakdown. These studies, coupled with our previous research, conclusively demonstrate that providing non-antibiotic alternatives to high-risk feedlot cattle can improve performance, health, and overall well-being. All data have been analyzed for these studies, results have been presented at scientific meetings, and manuscripts are being prepared for publication. For Objective 2, two final studies were conducted evaluating the influence of transportation on the feeding behavior of newly weaned beef calves and the influence of gestational stress on subsequent offspring. The major finding from the first study was that transportation duration, 6 versus 24 hours, did not affect the amount of time it took for calves to consume enough feed to meet net energy for maintenance requirements. In the second study, the influence of gestational stress on performance, health, and well-being of beef calves was studied. All calves in this study have been born, and researchers have collected birth weights, gestation lengths, and blood samples within 24 hours of birth. Data will be collected from these calves until weaning, at which time researchers will evaluate the influence of gestational stress on growth, immune system function, and other endocrine parameters. Preliminary results reveal that pregnant cows partially acclimate to repeated stressors, and that animal temperament and the transportation process influence the physiological responses to stress. Final data on the calves, an essential data set with regard to the development of specific management practices for cattle, will be collected in FY13.
1. Too much citrus in the diet can reduce cattle growth. Citrus pulp and peel are by-products from citrus production that have been commonly used as relatively low-cost, nutritional feedstuffs for ruminants. Previous research showed that feeding citrus pulp and peel can actually decrease pathogens such as E. coli O157:H7 and Salmonella typhimurium in swine and sheep. Scientists from the Livestock Issues Research Unit in Lubbock, Texas, teamed up with scientists from Texas Tech University, Mississippi State University, and ARS' Food and Feed Safety Research Unit in College Station, Texas, for a cattle study to evaluate the potential health and performance benefits of including citrus pulp in the diets of calves as they enter the feedlot. Results demonstrated that including citrus pulp in the diet can improve both the physiological and acute phase response of newly received feedlot heifers to an acute immune challenge. However, there appears to be a palatability issue such that dry matter intake is reduced and growth performance is negatively impacted when citrus pulp pellets are included in the diet at levels of 10% or greater.
2. Yeast supplementation for heat stress and cattle health. Alternative methodologies that enhance immunity and subsequent health of calves entering a feedlot have the potential to decrease costs associated with medication usage and the loss of gain associated with illness, and are consequently in high demand. Recent research at the Livestock Issues Research Unit in Lubbock, Texas, has focused on the potential of yeast products as a non-antibiotic alternative feed supplement that can improve productivity during several periods of cattle production, specifically by enhancing immune function and improving overall health. In a further study, scientists teamed up with scientists from Texas Tech University and Lesaffre Feed Additives, Milwaukee, Wisconsin, to determine the effect of yeast supplementation on performance during a period of heat stress. Results indicated that supplementing yeast products during a period of heat stress improved feed intake and gain without jeopardizing the health of the cattle. Additionally, yeast supplementation appeared to enhance the overall health status of the cattle which resulted in a reduced immune response when cattle were exposed to endotoxin. Collectively, our studies suggest that yeast products may be a viable feed supplement for cattle entering the feedlot in order to reduce the negative effects of illness on productivity while at the feedlot.
3. Taking baby for a ride, before it's born. We have previously reported that, contrary to popular opinion, transportation in and of itself does not appear to negatively impact the health, productivity, and overall well-being of yearling cattle, and that cattle are most stressed during handling and loading, rather than during transportation itself. However, information pertaining to the long-term consequences of exposing fetal calves to the transportation process is limited. Therefore, scientists from the Livestock Issues Research Unit in Lubbock, Texas, the Texas AgriLife Research Center in Overton, Texas, Mississippi State University, and Texas A&M University conducted a collaborative study to evaluate the influence of gestational stress on the subsequent performance, health, and well-being of beef calves. To induce the gestational stress, pregnant cows were transported for 2 hours at 60, 80, 100, 120, and 140 days of gestation. To date, all calves in this study have been born, and researchers have collected birth weights, gestation lengths, and blood samples for immune function and endocrine measurements within 24 hours of birth. For the cows, the results revealed that pregnant cows partially acclimate to repeated exposure to a stressor over time, and that both animal temperament and the transportation process influence the physiological responses to stress in gestating cows. Additional information and samples will be collected from these calves until weaning, at which time the calves will be allocated to various other studies designed to evaluate the influence of gestational stress on growth performance, immune system function, and various other endocrine parameters. This information will be extremely valuable to cattle producers with regard to the transportation of pregnant cattle.
4. The longer the ride, the greater the appetite. While we have previously demonstrated that transportation does not necessarily cause stress in cattle, the time spent without food and water during the transportation process could have a significant impact on subsequent health and performance. To gain a better understanding of how the transportation process influences these parameters in cattle, researchers from the Livestock Issues Research Unit in Lubbock, Texas, teamed with scientists from Texas AgriLife Research in Overton, Texas, Mississippi State University, and the Samuel Roberts Noble Foundation to evaluate the effects of abrupt weaning followed by transportation on feeding behavior of beef calves. As expected, the results from this study indicated that calves that were transported for a longer duration (approximately 24 hours) lost more weight than those calves hauled for a shorter duration (approximately 6 hours). However, calves hauled for the longer duration began consuming feed more rapidly after being transported compared to calves transported for a shorter duration. Interestingly, there was no effect of transportation duration on the amount of time it took for calves to consume enough feed to meet net energy for maintenance requirements, thus suggesting that regardless of the duration of transport the net effect on growth performance was not different between the two groups. This information will be useful to beef producers as they strive to develop management practices to improve health and performance of calves coming into the feedlots.
5. Feed additives help dairy and beef cattle. OmniGen-AF is a proprietary commercial product containing yeast, B-complex vitamins, and other GRAS (Generally Recognized As Safe) ingredients that have been used in the dairy industry for several years as a feed supplement and documented to augment immune function. Scientists from the Livestock Issues Research Unit in Lubbock, Texas, speculated that feeding this supplement to beef cattle would potentially boost immune competence. Therefore, a collaborative study was conducted with scientists from the Texas AgriLife Research Center in Overton, Texas, Mississippi State University, and Prince Agri Products, Quincy, Illinois, to evaluate the potential benefit of feeding OmniGen-AF to beef heifers prior to being exposed to transportation followed by a subsequent immune challenge. Results from this study indicated that this supplement primed the immune system of the calves in a manner that expedited the acute phase response to an endotoxin challenge, thus allowing them to recover quicker than the non-supplemented calves. The data also indicated that OmniGen-AF supplementation altered the metabolic response during the immune challenge by increasing available glucose prior to the challenge and reducing the need for these calves to mobilize energy through lipolysis and proteolysis. This study, coupled with our previous research in this area, conclusively demonstrates that providing non-antibiotic alternatives to high-risk feedlot cattle can improve performance, health, and overall well-being. Given the public's interest in eliminating feed grade antibiotics from cattle feedlots, this research is a significant step towards identifying potential alternatives that are economically feasible and will provide immune protection.
6. What energy source is best for the immune system? In a previous collaborative study, scientists from the Livestock Issues Research Unit in Lubbock, Texas, and Texas AgriLife Research revealed that high-strung or "crazy" cattle are metabolically different from calmer cattle. In fact, we found that "crazy" cattle use a different energy source compared with calmer cattle, even when their health is in jeopardy. To further elucidate the intricate connection between metabolites and the innate immune response, scientists from the Livestock Issues Research Unit in Lubbock, Texas, teamed with scientists from Mississippi State University to determine if increasing energy availability via an intravenous lipid infusion or bolus glucose injection would alter the innate immune response following exposure to an endotoxin. Results from this study suggest that increasing circulating concentrations of non-esterified fatty acids may modulate the innate immune response in cattle, and that the concentrations of non-esterified fatty acids previously observed in temperamental cattle may be responsible for the altered innate immune response reported in these cattle following an immune challenge. To our knowledge, these are the first data to demonstrate this particular metabolic/immune system connect in cattle.
Schwertner, L., Galyean, M., Hulbert, L.E., Carroll, J.A., Ballou, M. 2011. Effects of dietary source and intake of energy on immune competence and the response to an infectious bovine rhinotracheitis virus (IBRV) challenge in cattle. Livestock Science. 141(2-3):259-266.