Weaning – Part 2: The Ugly and The Good

– Kirsten Nickles, Graduate Research Associate and Anthony J. Parker, Associate Chair and Associate Professor. Department of Animal Sciences, Ohio State University

“The Ugly” – A stressful weaning experience negatively affects the growth rate and health status of feeder calves. Stressed calves become susceptible to pathogens and succumb to respiratory and gastrointestinal diseases during weaning (Campistol, 2010). Subjecting cattle to stressful periods such as weaning also impacts how society perceives the beef industry and the welfare standards currently implemented.

Modern consumers are becoming increasingly concerned with food animal agriculture and the production processes being utilized by producers (Olynk et al., 2010). Abruptly weaning calves onto a truck and into the marketing chain without conditioning the animals for the health and welfare challenges can be avoided with improved calf management.

The types of stressors endured by livestock at weaning can be divided into three distinct categories: psychological, physiological, and physical (Carroll and Forsberg, 2007). Exposure to new environments, restraint, and unfamiliar noise are psychological stressors. Physiological stressors are characterized as anything that causes deviation from homeostasis in the body such as not meeting nutrient requirements or disruptions to the endocrine system. Physical stressors are defined as anything causing harm to the animal such as injury, temperature stress, feed and water restriction, and disease (Carroll and Forsberg, 2007).

The goal at weaning should be to minimize a calf’s experience to multiple stressors at the same time. An important point to consider is that multiple stressors have a compounding effect on a calf’s behavior, tissue growth, metabolic, immune, endocrine, and reproductive systems (Price, 2013). It is well noted that a calf confronted with multiple stressors will have a weakened immune system. The calf may be unable to respond to pathogens in the same way as before the imposition of the stressors and will succumb to disease and potentially death. Multiple stressors become a catalyst for respiratory disease in feeder calves.

The USDA National Animal Health Monitoring System (2011) reports bovine respiratory disease (BRD) as the most common illness among calves entering the feedlot or stocker phase. Additionally, 97% of United States feedlots reported having cattle with BRD, and nearly 17% of all cattle on feed are affected with BRD (NAHMS, 2011). Since abrupt weaning is the most common weaning method in the United States, and only about 35% of small operations (1-49 cows), 60% of medium operations (50-199 cows), and 79% of large operations (200 or more cows) provide buyers with information about their calf health programs, it is common for calves to be vaccinated on arrival at the feedlot (NAHMS, 2017). It was also reported that over 60% of the producers that responded in the survey did not vaccinate their calves against respiratory disease before sale (APHIS, 2010).

Additionally, since most calves in the U.S. are abruptly weaned and immediately transported to the feedlot or stocker operation with unknown vaccination status, approximately 59% of feedlots will treat the entire lot of calves with antibiotics to help prevent an outbreak of respiratory disease (NAHMS, 2011). Treating the entire lot of calves with antibiotics is called metaphylaxis.  The use of metaphylaxis is more common with lighter weight calves (less than 700 pounds) compared with heavier cattle, however, 21.3% of cattle placed in feedlots were treated metaphylactically in the 2007 survey.

Vaccinations are a useful tool for the prevention of disease; however, vaccine efficacy is greatly reduced and can decrease dry matter intake and body weight gain when given to stressed calves at arrival to a feedlot (Blech et al., 1984). This reduced efficacy is because of the stress-induced immunosuppression that occurs in calves, and several research groups have reported that vaccination at arrival does not benefit and may even decrease health status of newly received calves (Martin et al., 1982; Perino et al., 1997; Richeson et al., 2009; Griffin et al., 2018; Schumaher et al., 2019). When calves are abruptly weaned and simultaneously subjected to numerous stressors, they are at greater risk for respiratory illness.

Additionally, when producers do not vaccinate for respiratory pathogens, and fail to disclose vaccination histories to buyers, the risk of failure in the feedlot increases. This then leads to increased vaccination on arrival and metaphylactic treatment of calves. There are other alternatives, however, to this ugliness that can result from multiple stressors at weaning. Calf conditioning programs are designed to minimize the novelty of future stressors and promote the health and resilience of calves.

Common “preconditioning” programs include an extended weaning period, coupled with a vaccination protocol, and in some programs a feeding regimen. In the marketplace longer weaned, preconditioned calves almost always sell for a premium price when compared to calves that have been abruptly weaned (CattleFax, 2021), and are unvaccinated. Next week we will take a look at several options for preconditioning calves and the reasoning behind various precondition practices.

“The Good” – The good news in the weaning narrative is that there are alternative weaning methods that have been scientifically tested and found to reduce the multitude of stressors placed on beef calves at weaning. For optimal welfare and productivity of our feeder calves, alternative weaning methods and vaccination protocols should be used rather than abrupt weaning. When calves are placed in a conditioning program, it decreases the number of stressors simultaneously placed on calves at weaning. Additionally, conditioning programs provide calves time to become accustomed to these stressors. This then eliminates the number of novel, stressful events that a calf endures when they travel to the next phase of production, as they have already experienced things like a new feed bunk and water system, for example.

To learn more about alternative weaning methods, read about Science based weaning methods for beef calves published in last week’s BEEF Letter. By selecting an alternative weaning method and enrolling calves in a preconditioning program in which they are weaned before being trucked, have received some sort of vaccination protocol, we will be giving calves their best chance at being healthy when they enter the feedlot. By weaning and vaccinating before transporting calves to the feedlot, calves will have a chance to mount an adequate immune response and be less stressed as they enter the next phase of production. This will improve all sectors of the industry and allow us to produce the best product possible for our consumers.