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Extension > Agriculture > Dairy Extension > Calves and heifers > Give them some A.I.R.

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Give them some A.I.R.

Jim Paulson, Extension Educator-Dairy

July 9, 2011

Take Home Messages:

In recent years, use of automated calf feeding systems for pre-weaned calves has increased. However, challenges have arisen with respiratory problems in some housing systems. The question is: Are there more problems with calves fed with an automated calf feeding system? Respiratory infections have always been a problem for pre-weaned calves raised in confinement. This problem led to widespread use of calf hutches but even with better ventilation using hutches, we still observe respiratory problems.

Typically, we think of cleanliness with regards to clean pails, clean water, clean nipples, clean calving pens, and clean feed. But, clean air (i.e. ventilation) must also be considered. Think of ventilation or air as A.I.R. Adequate, Incoming and Removal. This can be a challenge in naturally ventilated buildings that rely on outside air currents, side openings, and convection air currents within a building. Calves, being small, do not generate a lot of body heat, which limits convection air currents. Thus, there is very little mixing of air in a building and potentially minimal exchange of air from the building, leading to buildup of ammonia and humidity.

Calves must be kept comfortable. There are two keys to calf comfort: soft and dry bed, and ventilation. Calves will spend 75% or more of their time lying down (18 hours or more per day). For maximum lying time, calves need bedding depth for nesting and for moisture to soak away. Nesting is crucial in cold temperatures to conserve body heat. Calves have a large body surface to body weight ratio and are low in body fat, so are prone to lose body heat in colder temperatures, especially if they are wet.

Wet bedding brings another potential problem: production of ammonia at the bedding surface, from the combination of urine, manure and bedding. Ammonia levels above 5ppm at the calf nose level are harmful. Potentially, this problem is greater if calves are consuming greater amounts of liquid daily. Typically, calves fed by an automatic feeder are fed greater amounts of liquid and solids per animal per day. Free choice consumption of water increases with greater solids intake. Additional water for calves fed an accelerated milk replacer is critical for this reason. A high percentage of water consumed returns to the calf environment either as urination, respiration and a little as perspiration. When a calf is young and only drinking milk, it is estimated 80% of liquid consumed will be excreted as urine. When a calf begins to consume dry grain and hay, a greater proportion of water is excreted in the feces and less in the urine. Water restriction at this time will increase the concentration of urine. If access to water is severely restricted, calves will decrease dry matter intake to reduce water needed for fecal output to maintain a minimum urine volume.

Areas around the feeder and water fountain are usually wetter and prone to ammonia production. It is critical to have adequate amounts of bedding and more than 30 sq. ft. of space/calf. Although the amount of bedding used will vary between farms, an average of one pound of shavings/calf/day has been reported. This is insufficient to absorb the amount of urine produced. The type of base will affect bedding needs as well. Many successful calf raisers will initially put down 20-25lbs of bedding or combination of bedding per calf, whether in hutches or group pens, and follow with 2-3lbs of new bedding per day. These amounts provide a good base of bedding to soak up liquid, and provide insulation and nesting ability in cold weather.

What kind of bedding is best? There are a wide variety of bedding materials; some have greater water absorbing potential than others, which influences the amount needed (see table) However, the amount used is more important than the specific material used. Wet or dirty knees, hocks or legs indicate insufficient amounts or not bedding often enough. In cold weather, use straw alone or in combination with shavings to allow for nesting.

Successful calf raising can be accomplished whether it be in hutches, individual pens or in group pens with automated feeder systems. Success is dependent on achieving high performance of many variables. Critical among these are sufficient bedding amounts to eliminate heat loss in cold weather; preventing excess ammonia production in wet bedding; air exchange rates to remove humidity, ammonia, and odor; and nutrition for growth.

Water Absorption of Bedding Materials

Pounds of water absorbed per 100 lb of dry bedding

  Top quality pine 250
  Run-of-the-mill hardwood 150
Wood shavings  
  Top quality pine 300
  Run-of-the-mill hardwood 150
Wood chips  
  Top quality pine 300
  Run-of-the-mill hardwood 150
Tree bark (dry, fine) 250
Wheat Straw  
  Long 220
  Chopped 295
Oat straw  
  Long 280
  Chopped 375
Oat hulls 200
Corn stover (shredded) 250
Corncobs (crushed or ground) 210
Barley straw 210
Hay (mature, chopped) 300

Adapted from Antoniewicz. 2006. (2)
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