Bovine respiratory disease in dairy calves can have profound production and economic consequences in the short-term and even later in life. Early intervention is critical to reducing the short- and long-term effects of the disease. It’s important to understand sickness behaviors and respond quickly.
“Sickness behavior occurs in all mammals and is a coordinated set of responses to infection,” says Amy Stanton, calf-health researcher at the University of Guelph in Canada. “This includes people, such as when they get the flu.”
Stanton says we are still identifying how sickness behaviors are presented in cattle, but from other species we know they include:
- Decreased appetite. Is this subtle or pretty dramatic at the onset of sickness? It can be either. Decreased appetite in milk-fed calves alters depending if they are fed ad libitum or restricted. Early signs for ad libitum fed calves are more likely to be decreased appetite, while limit fed calves are less likely to try the milk feeder when they are not eligible to be fed.
- Decreased energy/lethargy. Calves are more likely to be lying down. (See “Encouragement to rise score” sidebar)
- Decreased thirst. Is this subtle or dramatic? This can be hard to detect without close monitoring.
- Apathy. For example, the calf doesn’t care about human interaction or the feed bucket being filled up.
- Energy conservation. “Short-lying,” with the head tucked into body, may be one indicator.
- •Depression. Indicators include poor coat quality, lowered head, apathy and dull eyes.
“All of these behaviors and clinical signs have been shown to increase the potential of surviving an infection without medical intervention,” Stanton notes. Some of these behaviors have been addressed in calves, but further research is needed.
In a study involving 800 individually housed calves between zero and eight weeks of age, “we looked at various measures which we suspected could help us identify sick animals based on sickness behavior,” Stanton explains. Stanton’s results included:
- “Statue standing” and holding the neck below the chest in calves less than 2 weeks of age was associated with lower average daily gain. This behavior is usually observed when animals have visceral pain. (See photo.)
- Lethargy. If calves have very little response or are slow to respond to a person’s entry into their space, this may be a sign of disease. An “encouragement to rise score” greater than 3 is associated with decreased average daily gain.
- Less willingness to approach. Besides having a natural curiosity, milk-fed calves associate people with food. If suddenly calves fail to display this behavior, astute calf-care personnel may pick up on subtle signs of inappetance or apathy.
Identify poor growth
Factors that can cause poor growth in a dairy calf include poor nutrition, bovine respiratory disease, stress, poor environment and more.
Identifying causes of poor growth is challenging since so many variables can affect it.
“Basically, we are looking for calves that are not performing as expected,” Stanton notes. “These are animals that, either due to increased energy demands due to disease or decreased appetite, are below the targeted weight gain. These animals are most likely to require some attention due to either the need for treatment or additional attention to increase their feed intake, especially calves during or shortly after the weaning process.”