Dairy heifers need some fresh air
Fresh air is something we sometimes take for granted out in the country. We give considerable thought and effort to making sure our milk replacer program is right or our pasteurizer is working correctly, but perhaps we should think more about the quality of air in our calf and heifer facilities.
Ammonia (NH3) is a good marker for other noxious gases, including hydrogen sulfide (H2S), methane (CH4) and carbon dioxide (CO2). In other words, when ammonia levels are elevated, it’s a good chance the concentrations of these other gases are high as well.
Ammonia can potentially affect calf health and growth. The duration of exposure, the concentration of air ammonia, and the presence of other aerial pollutants, such as carbon dioxide (CO2), bacteria, and bedding particles, may negatively impact heifer performance. That’s likely because these pollutants cause inflammation, which has been shown to decrease feed efficiency.
The key challenge is to manage bedding moisture when environmental temperatures are elevated and when barn airflow rates are compromised. Weaned heifers in the 200-to-300-pound range present a greater challenge as they still require significant amounts of bedding to keep warm and produce considerably more urine and feces than pre-weaned heifers.
It is also difficult to manage air quality in barns that house both pre-weaned and older heifers. Increased airflow may be necessary for the older animals since their pens likely have higher concentrations of ammonia and other gases. However, the increased airflow may create too much of a draft for young calves. Work with a ventilation specialist to design a ventilation system that best fits your facilities.
Where does air ammonia come from?
Nitrogen in manure can be converted to ammonia through bacterial degradation. Concentrations tend to be greatest above the bedding and in the wettest part of the pen, and generally peak during warm and humid times of the year.
How can air ammonia be measured?
Estimates of air ammonia can be measured with simple-to-use test strips (shown in photos) or more sophisticated sampling and detection equipment. Learn more in this Vita Plus technical bulletin.
How much air ammonia is normal?
It’s difficult to pinpoint the “normal” ammonia concentration for calf or heifer barns. University of Wisconsin researchers (Lago et al., 2006) measured average air ammonia concentration of 2.2 ppm, with a range of 0 to 4.0 ppm, in naturally ventilated calf barns. Similarly, researchers in Germany (Seedorf and Hartung, 1999) reported 3 to 7 ppm air ammonia in calf barns.
According to Urbain et al., 1994, the safe threshold for air ammonia for dairy calves is 15 to 20 ppm. Calf health is significantly impacted at this concentration. However, field experience indicates that calf performance can be impacted at much lower levels. Therefore, one goal is to keep air ammonia concentrations below 5 ppm.
What impact does high ammonia have on nursery calves?
Data directly measuring air ammonia impact on calf growth and health is difficult to find. In growing pigs, increasing air ammonia of 10, 50, 100, and 150 ppm had significant adverse effects on feed intake and average daily gain (Stombaugh et al., 1969). Korean researchers reported a significant decrease in feed efficiency and lying time in growing pigs (Choi et al., 2011). Hamilton et al., 1996 reported increased risk for Pasturella multicodi respiratory infection in swine when air ammonia exceeded 5 ppm.
What can I do if my barn air ammonia is greater than 5 ppm?
- Increase the air exchange rate.
- Manage curtains and turn on fans as the environment dictates.
- Provide adequate bedding to absorb moisture and remove wet and soiled bedding frequently.
- Increase drainage under bedding by using porous materials or drains.
- Increase drainage from water fountains and automated calf feeders by adding drains and sloping floors toward drains.
- Decrease stocking density and avoid overcrowding.
- Move older heifers out of the nursery.
- Evaluate dietary protein intake. Feeding protein amounts that closely reflect maintenance and growth requirements will decrease fecal and urine nitrogen output.
- Design heifer facilities that allow for easy cleaning and minimal constraints to natural airflow (design with low sidewalls).
In summary, air quality is an important component of successful nursery calf facilities as well as heifer facilities. It is likely a bigger challenge to manage – and perhaps neglected more often – in transition heifer and heifer growing facilities as these animals produce more urine and manure. Use ammonia test strips as one tool to evaluate air quality and then make informed decisions regarding ventilation, bedding, stocking density, and dietary protein.
About the author: Dr. Noah Litherland is the Vita Plus dairy youngstock technical specialist. he grew up on a diversified livestock farm in central Illinois and was active in 4-H and FFA as a youth. He earned his bachelor’s, master’s and Ph.D. from the University of Illinois, focusing on dairy cattle nutritional physiology. He worked as a dairy extension specialist at Oklahoma State University from 2006 to 2008 and then as a dairy nutritionist at the University of Minnesota until 2014. At Minnesota, Litherland served as the faculty supervisor of dairy research on the St. Paul campus.