The bovine respiratory disease complex (BRD), sometimes called shipping fever or pneumonia, is an economically-important disease and a leading cause of death loss in beef cattle in North America. Survey data from the National Animal Health Monitoring Service in 2011 suggests that respiratory disease accounts for 29.1% of all calf death losses in the United States. BRD is manifested as a complex of several types of infection with specific causative organisms, clinical signs and related economic impacts. Organisms known to cause BRD include infectious bovine rhinotracheitis (IBR) virus, bovine viral diarrhea (BVD) virus, bovine respiratory syncytial virus (BRSV) and parainfluenza type 3 (PI3) virus. Bacterial agents such as Mannheimia haemolytica, Pasteurella multocida, Haemophillus somnus and mycoplasma are also contributing factors.
Amount of exposure, pathogen virulence and host immune factors all influence risks associated with BRD. The incidence of BRD in calves can be affected by passive immunity received from colostrum and environmental factors such as weather, temperature and humidity. Age, gender, nutritional status, genetics and other factors also affect the incidence of BRD. Vaccination programs, antibiotics and management are key factors in protecting herds and keeping them healthy.
Beef Cow Nutrition and Calf Health
Feeding beef cows to gain maximum profitability can be a challenge. Feed costs are typically the highest input costs in a cow/calf operation. There is a tendency to try to achieve maximum profitability through the use of the cheapest feeds available. This can be a route to quick profits; however, it is rarely a long-term solution. Restriction of certain nutrients through the use of poor-quality feeds can decrease weight gains, reproductive performance and even calf health. Studies have mainly focused on protein, energy, macro- and micro-nutrients and their effects on production and health. Ensuring the requirements for energy, protein, macro- and micro-nutrients are being met is crucial in maintaining reproductive performance of cows and producing healthy calves. Inadequate cow nutrition is related to calf morbidity and mortality. There are critical times in fetal development in which nutritional conditions can affect neonatal health and growth of the calf as well as susceptibility to disease later in life.
Nutrition and Immunity
Nutrition of the pregnant cow can affect the amount of innate immunity passed to the calf through the dam’s colostrum (first milk). Proteins consist of amino acids, which are the foundation for enzymes, antibodies and other functional proteins of the immune system. Antibodies passively transferred to the calf immediately after birth are crucially important in protecting baby calves from disease challenges. Very few studies have looked at the effect of restricted protein diets fed to pregnant cows on immune function of calves.