Ensuring the health and productivity of starter cattle is a complex challenge. One of the critical aspects of managing this is understanding and supporting their immune systems, especially during the stressful transition from pasture to backgrounder or feedlot. This article delves into the various stressors starter cattle face, the role of their immune systems in combating disease and the nutritional interventions that can enhance their immunity.
Starter cattle stressors make them more susceptible to disease challenges
Transitioning cattle from pasture to feedlot is a stressful time. Cattle undergo a change in diet and environment, are hauled, have feed and water withheld, and are commingled, vaccinated and implanted, among other things. Any of these may cause a disturbance in the rumen and severely disrupt the rumen microbial balance, reduce rumen bacterial populations and decrease rumen fermentative ability. These stressors can also cause clinical sickness; however, many calves may not exhibit any outward signs of illness. Still, you can be assured that, even if cattle do not appear sick, there is a performance loss associated with these stressors.
To reduce stress, avoid processing cattle immediately upon arrival. Some experts recommend waiting an hour for each hour spent on the trailer. However, some situations may call for a more extended delay. It’s best to consult with your veterinarian on your specific situation.
Depending on your animal handling techniques, people can also significantly add to stress or help prevent it. Efforts should be made to work calmly and minimize yelling, running and the use of electric prods. Cattle should be kept comfortable in a pen that protects them from the elements and is clean, dry and well-bedded. A sufficient supply of fresh water should also be available and located where it can be easily found. Long-stem grass hay should be available soon after arrival to get the rumen going again, while grain should be offered a bit later and at a slower rate.
Stronger immune systems better withstand disease challenges during stressful situations
The animal’s skin and epithelial tissues provide a barrier to keep pathogens outside the animal. If, however, viruses or bacteria get past that barrier, the immune system springs into action. The health of cattle benefits from both innate immunity and adaptive (acquired) immunity.
- Innate immunity is the first line of immune defense against a wide variety of pathogens. Responses of the innate immune system are “nonspecific” – meaning they do not distinguish between invaders. Instead, they respond to features common to many types of pathogens. Innate immunity provides fast-acting recognition and removal of pathogens. However, innate immunity is not specific to a particular organism, and if the pathogen survives or evades removal, the adaptive immune system steps in to assist.
- Adaptive immunity is targeted protection against specific disease-causing agents. Adaptive immunity works alongside innate immunity to protect against specific disease-causing agents. These include specific viruses and pathogenic bacteria. Adaptive immunity involves a “memory” of the pathogen and takes time to produce specific immune cells and antibodies to fight the infection. The adaptive immune system is what is being built when producers give specific vaccinations to cattle. Those vaccines are “educating” the immune system to be able to recognize and defend against a specific pathogen if it sees it in the future. However, in addition to being a bit slower, one downside of the adaptive system is that it draws more metabolic energy, which then takes available energy away from body maintenance, growth or other productive functions.
Ensuring that both the innate and acquired immune systems are on point and ready to respond quickly and robustly is the best defense against disease challenges. In most cases, this allows the animal to stay healthy and perform to its genetic potential. However, when the immune system is compromised, is slow to react or does not respond strongly enough, clinical sickness can occur.
Specific interventions to enhance calf immunity and withstand disease challenges
Not every animal’s immune system is created equal. The immune status of cattle is dependent on a number of factors. Cattle that have been on a higher plane of nutrition, with adequate energy, protein, mineral and vitamin supplementation, are generally going to have an immune system that is more robust. Likewise, cattle that have been previously vaccinated are going to have an acquired immune system that is better educated and ready to respond to specific challenges. Additionally, some postbiotic immune support products can be provided through the feed or in a drench that can help support the immune system, allowing it to respond more quickly and robustly when needed. These products are unique because they are not considered drugs, thus no Veterinary Feed Directive (VFD) is required. They can also be used in conjunction with antibiotics if desired.
Research conducted by Iowa State University, the USDA Agricultural Research Service (ARS) and other institutions has clearly shown the benefits of these products for priming the immune system and decreasing sickness behavior of cattle.
More specifically, a study was conducted at Iowa State to determine the effects of a postbiotic supplement on immune function and bovine respiratory syncytial virus (BRSV) infection in young calves. Results of this study indicated that calves consuming a postbiotic prior to and after an experimental insult of virus inhalation had fewer clinical signs of respiratory disease and less damage to their lungs (Figure 1). They also shed less of the BRSV, which may reduce the spread of the virus.
In closing, remember that all cattle endure some level of stress upon arrival at the feedyard or backgrounding facility. Efforts made toward reducing that stress and supporting the immune system will pay big dividends toward keeping cattle healthy and performing to their genetic potential. Utilizing tools such as postbiotic immune support products can aid in improving animal health and well-being while improving the odds of long-term sustainability and profitability for that operation.
References omitted but are available upon request by sending an email to an editor.
