To close or not to close?
"To close or not to close?" is one of those questions that many dairy producers are asking themselves as they walk through their dairy facilities. "Do I close the curtains and ridge vent or do I leave them open?" It seems to be fairly easy to figure out when this needs to be done on milking cow facilities because someone is generally working with these animals many hours out of the day and knows when they need to be closed. But what about youngstock and weaned calves; or a better question, "When do you close the air vents on calf huts and super huts?" There are several research papers and University trials that discuss ventilating calf barns whether they are group housing or individual stalls. This is not the case for ventilating individual and group calf hutches.
With all of the articles and documentation suggesting ventilation is the make or break point for successfully raising a calf to become a productive adult cow, it is easy to see that there is a great amount of detail that needs to take place in all livestock facilities for ventilation.
Typically, when discussing ventilation for calves, the goal is an optimal number of air exchanges per hour. The target for winter ventilation is four complete exchanges per hour. This can be done either mechanically or naturally. When working with calf hutches, natural ventilation is your only option.
Most important for winter ventilation in calf housing is to avoid drafts at all costs. Shoveling snow around the outside base of the calf hutch will eliminate any chance of a draft working underneath the bottom of the hutch. Many calf hut manufacturers include top and rear vents of some kind in their design. For most of the winter, the rear vent will be closed to prevent a draft; however, when it comes to the top vent, it is difficult to know when to completely close or to leave partially open. It is suggested to think of the top vent as a curtain on a freestall barn that needs to be opened and closed as the weather changes. On days when temperatures don't get much above zero and with subzero wind chills, it would be safe to leave the top vent completely closed to prevent cold air movement through the hutch. Days that warm up above 25 degrees Fahrenheit present the most challenges. It would be best to at least have the top vent one quarter or half way open to help with the air exchanges.
There is no clear recommendation for a specific vent position when a certain temperature is reached. The numbers of variables that are present on any given farm are countless. Some farms may have a large number of hutches and some of those may be more exposed to the wind than others. This will affect the amount of air allowed to move through the hutch. Others farms will be able to create a wind break that will allow for the hutches to be set up the same throughout.
Other factors that lead to successful calf raising in calf hutches include hygiene and the diet. There have been a number of research studies on hygiene that show cleaning the hutch between calves is beneficial and greatly reduces the exposure to bacteria, which should result in fewer calves needing treatment. Providing a high quality milk replacer or pasteurized waste milk with the proper amount of solids will ensure calves are receiving enough energy to maintain body temperature during extreme temperatures. This, in combination with a high quality starter that is highly palatable and does not contain a large amount of fines, will also help calves maintain an ideal rate of gain. It is also widely accepted that calf blankets go hand in hand with hutches as well as many other calf housing facilities in the winter.
Though there seems to be a large push to see many dairy calves raised in group housing, there will always be a need for individual calf housing of some form on many dairy farms. Hutches are still a very economical and effective way of raising high quality calves for today's and tomorrow's dairy farm.
Published in Dairy Star November 24, 2012