By Lindsay Ferlito & Casey Havekes, Cornell Cooperative Extension North Country Regional Ag Team
Over the past year and a half, we’ve received several requests for calf barn ventilation support. Some of the most popular questions have been, “I’m thinking about building a new calf barn. What ventilation system works best?” Or, “I just built this calf barn but I’m having a ton of respiratory challenges. What is going on?” And last, “How can I retrofit this old facility to provide better ventilation for my calves?”
The simple yet complex response to all of these questions is that there is no ‘one size fits all’ approach. Unfortunately, due to the complexity of prevailing winds, the direction of barns, wind shadows, mechanics, and a variety of other variables, there are so many different moving parts when it comes to calf barn ventilation.
To begin addressing the incoming questions, we designed an exploratory research project that aimed to investigate a variety of different calf barn housing and ventilation systems across Northern New York. This research project was funded by the Northern New York Agricultural Development Program. One of the study objectives was to evaluate air flow and air exchanges through ‘fogging’ the facilities. The study enrolled 15 calf barns across northern NY. Many others have reached out through word of mouth and because of our outreach efforts. To try to capture some of the complexity and uniqueness of each calf barn, we compiled 5 of the most interesting case studies that arose because of our study and further troubleshooting efforts. The assessments and solutions described in this article are the result of a collaboration between participating farms, herd veterinarians, Cornell Cooperative Extension Dairy Specialists, Lindsay Ferlito and Casey Havekes, and PRO-DAIRY Strategic Farm Planning Specialist, Tim Terry.
Case Study #1
Facility Description: Calves are group housed and fed acidified milk ad libitum. There are positive pressure tubes above calves, as well as fans on one side of the barn.
Problem: The farm owner mentioned a high number of respiratory cases and high treatment rates which is consistent with the herd veterinarian’s higher than usual lung ultrasound scores.
Assessment: It was a hot breezy day and all side wall curtains were open. The overhead doors were open on each end of the barn. There was air moving in every direction with some circling in one corner of the barn. It appeared that there was too much going on at once with the fans and tubes running, the open side curtains and open overhead doors on each end of the barn.
We also noticed that the bins holding the acidified milk were blocking some of the air movement across the pen from the fans. This resulted in dead spots and pooling directly surrounding the feeding bins.
Solution: We came up with two potential solutions for this facility. One option involves removing the fans from the side wall and installing new fans in two rows about the calves (one row on each side of the center feed alley). The other option involves closing the overhead doors and cross-ventilating by adding a bank of fans to the side walls. A concern with the latter option is that the bins holding the acidified milk will block too much of the air and consequently the air quality will be poorer directly behind this area. The farm owners are still working through these action plans to assess which option will work best for them.
Case Study #2
Facility Description: Calves are group housed and fed with automated feeders. There is one tube above the calves.
Problem: The farm owner mentioned a high number of respiratory cases. Additionally, as you can see in Figure 2, there is bird netting below the tube which is potentially impairing air flow.
Assessment: It was a cool, fall day the day we did the assessment. On one side of the barn, the top curtain was all the way open and the bottom curtain was all the way closed. On the other side of the barn, both curtains were all the way open as well as the overhead end doors. After the fogging, we noticed that although the fog came through the tubes properly and reached calf level, the dust covering the bird netting could be impeding air flow through the tubes. We noticed that there was a dead spot around calf level towards the closed side curtain. Additionally, we saw that the closed curtain was ‘bulging’ out because air wanted to get through, despite the curtains being closed.
Solution: We recommend cleaning the bird netting or removing it entirely. We also recommended opening the bottom side curtain a minimum of 6 inches so that the air moving across the barn could get out and keep moving across at calf level.
Unless precipitation is entering the building or bedding is being blown off the pack, the curtains should remain open. If these recommendations do not improve ventilation during the summer months, we suggest considering adding two summer positive pressure tubes to supplement the natural ventilation.
Case Study #3
Facility Description: Group housed calves fed ad libitum acidified milk. There are several tubes above the calves, and curtains on the side walls.
Problem: Farm owner has observed high respiratory issues and high treatment rates. One of the side walls also requires maintenance and as a result the curtain must stay up on that side of the barn to prevent calves from getting loose. Several of the tubes also require maintenance and are not functioning.
Assessment: The day of the assessment was hot with very little wind. Fogging demonstrated pretty good airflow and exchange in most of the barn except for the pen that had curtains blocking the wall. The fog stayed in that area for over 15 minutes (the objective is for the fog to clear within 1-2 minutes to achieve proper air exchanges for summer conditions.
Solution: We recommend the farm fixes the side wall so the curtain can be lowered in order to achieve proper air exchanges in that section of the barn. We speculate they can get closer to the recommended 40-60 air exchanges/hour for summertime by having all the tubes running. As a result, we also recommended the broken tubes be fixed, and all tubes be cleaned so they can run as designed.
Case Study #4
Facility Description: Calves are group housed and fed acidified milk ad libitum. The barn utilizes neutral and positive pressure for ventilation. This system incorporates a bank of fans behind the wall with the hole cutouts, pictured to the right (inlet side). There is an identical wall on the opposite side of the barn with a bank of fans behind it (outlet side). One side pushes air through the holes while the other side pulls air out through the holes and exhausts it out of the building.
Problem: The farm owner questioned whether the system was truly doing what it’s suppose to do. The farm owner also mentioned that at times, the end doors stay open and questioned whether that was having a negative impact on the efficacy of the ventilation system.
Assessment: The day of the assessment was hot and breezy. We fogged the barn once with the end doors open and then again with the end doors closed. When the end doors were open, the prevailing wind counteracted the air coming through the inlet holes and basically pushed it back out through the open curtains. As a result, it was obvious that the fog did not move properly across the pens. When we fogged the barn with the end door closed, air movement was better. However, there was still dead spots and inadequate air exchanges for summer.
Solution: We recommend installing more fans in the inlet side to help push more air through and increase air exchanges. We also recommend keeping the end doors closed so that the ventilation system can properly do its job without interference from prevailing winds.
Case Study #5
Facility Description: Calves are individually housed. The barn relies on natural ventilation. There are side wall curtains and 3 chimney exhaust fans.
Problem: Very high treatment rates and respiratory cases. There is also a second calf barn directly behind this barn that is used to house older, weaned calves. This barn creates a wind shadow for the barn housing the younger animals. The barn prevents fresh air from getting to the calves. This area also gets very cold in the winter making it especially difficult to ventilate it appropriately.
Assessment: The day of the assessment was a cool, breezy, fall day. Ventilation felt adequate, although we previously went on a very hot, summer day and felt that there was little to no air movement. Our assessment discovered winter ventilation is likely adequate, however, there is not sufficient air flow coming into the barn to meet summer ventilation requirements. This is largely influenced by the new barn creating a wind shadow and preventing air flow into the barn.
Solution: We recommend designing tubes to supplement summer ventilation. Two tubes will hang above each bank of calves and they will be turned off during the winter. This will help the facility achieve the recommended air exchanges for summer. Owners should also consider housing younger calves in the new facility – prevailing winds will carry from younger to older.
Also, the cropping rotation will have to consider physically smaller crops in the adjacent field. Larger crops plus the existing knoll upwind from the facility creates a wind shadow.
There are so many factors to consider when troubleshooting calf ventilation systems. Here are a few important takeaways from previous research and our case studies:
- Summer Ventilation requires 40-60 air exchanges per hour and winter ventilation requires 4 air exchanges per hour.
- Naturally, we want to open everything up on hot summer days. However, it may not be the best idea if you’re ventilation system is designed to have the barn closed up.
- Air will always take the path of least resistance. Keep this in mind if you have structures and equipment in the barn that could impede air flow.
Finally, you don’t have to tackle calf barn ventilation alone. Regardless of where you are reading this from, reach out to your local Extension agents, your herd veterinarian, or a trusted calf advisor to get started if you need help troubleshooting your ventilation system.
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