It’s easy to access, non-invasive, and could provide a window into the health status and welfare of calves. What is it? Believe it or not: saliva.
Animal scientists are researching the telegraphing abilities of saliva in various animal species, including calves. By analyzing its chemical properties, saliva – and changes in its composition over time – can signal stress, inflammation, immune response, and sometimes the presence of disease-causing pathogens.
A recent study by Hungarian researchers measured the cortisol levels in saliva of newborn calves. They found that the levels went up precipitously for all calves immediately after birth, signifying that birth and acclimation to the post-birth environment are highly stressful for calves.
Most significantly, calves that experienced dystocia exhibited much higher salivary cortisol concentrations compared to calves with a normal birth, likely due to prolonged parturition and/or forced extraction.
Another study conducted is Spain also looked at chemical markers in saliva to monitor systemic oxidative stress and compensating antioxidants. They found that when calves were weaned and commingled into larger groups, oxidant molecules increased, which in turn triggered an increase in antioxidants.
This information is valuable from a research perspective because saliva can be sampled using a non-invasive method to assess animal welfare and health, avoiding more painful, time-consuming, and invasive procedures such as blood and tissue sampling. Saliva sampling is noted to be fast, accurate, and cost-effective, and for these reasons can be performed very frequently.
At a more practical level, saliva samples could help determine less-stressful methods of managing and transporting calves. In the future, automated saliva sampling also could possibly trigger alerts for calves on the front side of a disease challenge like pneumonia, or adult cows in the early stages of lameness or metritis, as a few examples.
Saliva also could serve as a tool to determine the best timing for management practices like administering vaccines. If calves are found to be in a state of high oxidative stress based on a simple saliva test, vaccination could be delayed until those levels come down.
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