In talking with dairy farmers, it is obvious that more and more farms are switching to group housing and group housing with automatic feeders for pre-weaning calf rearing. Aside from the labour benefits, farmers and calf-health experts point to better opportunities for calf socialization and the ease of distributing the calf’s milk or replacer ration over more meals as obvious benefits. A big concern though is whether group housing leads to a decrease in health.
Group housing has been around for long enough now that research on how well it works is being published regularly. Group housing has also been adopted in enough countries that we are getting research coming from various sources.
A few years ago, research on the health of calves raised in group housing in Ontario found that 23 % of calves were observed to have diarrhea and
17 % were observed to have pneumonia. That data was collected during four visits to 17 herds located near Guelph. Calves were considered to have pneumonia or diarrhea using a standard scoring method that was adapted from Dr. McGuirk’s Wisconsin scoring system. Without having information on the health of calves raised in individual housing, it is not possible to determine if health issues were different between the two management systems.
A study published this year on dairies in California also used a scoring system to determine whether calves had pneumonia. After visiting 100 farms, the researchers found that an average of about 7 % of individually housed calves had pneumonia compared to 15 % of group-housed calves. The groups were not large. They ranged from 2 to 30 calves with an average of 9 calves.
Another recent research study, this time on dairy farms on Quebec, was able to look at both individually housed and group housed calves too. The researchers used ultrasound of the chest as the means to diagnose pneumonia rather than a scoring system. By collecting health information over a year, the researchers were able to look at the impact of seasons on health, as well as on the impact of group versus individual housing. They found that calves were just about twice as likely to have pneumonia in winter (15%) compared to summer (8%). They also found that calves were about twice as likely to have pneumonia if they were group housed (20%) compared to individually housed (10%).
To try to separate the impact of housing and feeding strategy, researchers in the UK compared health of calves in group housing and fed free choice to calves that were housed individually but fed a controlled amount (3 litres twice daily). Even though they had access to more milk replacer, group-housed calves were almost 4 times more likely to get diarrhea and almost 6 times more likely to get pneumonia. The researchers proposed that being housed in a group increased the chances that calves would develop diarrhea. They also proposed that feeding from a common nipple in group housed calves likely contributed to the risk of pneumonia.
The findings from these studies seem to make it clear that group housing may represent a greater health risk to dairy calves. It may be possible to reduce some of this risk by adopting better disease prevention plans when switching to group housing.
It is also equally important that farmers recognize the increased risk to calf health when it comes to looking for sick calves too. Relying on how much a calf drank may not be the best approach. There are at least two calf health scoring systems that do a good job of helping care providers identify sick calves earlier. Using either of them won’t reduce the calf’s risk of getting sick but they may help ensure that calves are seen to be sick earlier so they can be treated sooner.
Dr. Robert Tremblay is a veterinarian for Boehringer-Ingelheim and lives near Guelph.