Best management practices for group housing of preweaned dairy calves
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- Colostrum management
- Consistency and cleanliness of the milk diet
- Daily milk allowance
- Keep group size as small as possible
- Stocking density
In recent years the Midwest has seen an increase in interest by some producers in adopting group housing systems for preweaned dairy calves. Options for milk delivery systems for group-housed calves include computerized feeders, mob (hand) feeding of fresh milk, or free choice acidified milk. Group housing systems offer certain potential benefits including increased flexibility of labor (though not necessarily labor savings), ease of delivery of milk, and allowing calves more opportunity to exercise and socialize. However, producers should also be aware that comingling preweaned dairy calves in groups will increase the opportunity for disease transmission, thereby significantly increasing the risk for illness and mortality.
Baby calves, like human infants, have functional but immature immune systems that are not immediately prepared to fend off infectious disease challenges. Diseases can be avoided or limited if we can minimize exposure to infectious agents while increasing immune resistance so that calves can more successfully prevent and/or more quickly recover from an infection. So why is disease risk increased in group-housed preweaned calves as compared to calves housed individually (e.g. hutches)? Put simply, it is because we are breaking a basic rule of biosecurity; by putting calves in groups we are now allowing direct contact between calves. If even one calf in the group is ill and shedding an infectious agent at that time, depending on the nature of the pathogen, this can now be easily transmitted to every other calf through nose-to-nose contact, aerosol transmission, or through contact with a contaminated environment or surfaces (e.g. contaminated bedding, waterers, or a shared nipple).
Producers interested in adopting group housing systems should carefully weigh the potential advantages and disadvantages before making the decision on whether or not these systems are right for the dairy. This will include some consideration of their goals and priorities for the calf rearing program (e.g. goals for growth, goals for health, etc.). Producers already using group housing systems should implement management strategies designed to mitigate disease risk. The rest of this article will discuss best management practices when using group housing systems for preweaned dairy calves. Some of these recommendations are universal, meaning that they apply to any kind of housing system, while others are specific to group housing situations.
A good colostrum management program is the first cornerstone of any successful youngstock program. This can be monitored through periodic evaluation of serum total protein concentrations in one to seven-day-old calves. Producers can visit with their herd veterinarian about setting up a monitoring program.
Consistency and cleanliness of the milk diet
Whether feeding milk replacer or whole milk, the consistency and cleanliness of this diet are very important to the calves.
- Consistency and level of total solids (TS) in milk can be estimated and monitored using a brix refractometer (Goal: TS between 12.5 and 13.5%, never exceeding 15%. No more than a 1% fluctuation in TS should occur from meal to meal).
- Cleanliness of milk or milk replacer can be monitored by doing periodic cultures of milk (Goal: Total plate count < 20,000 cfu/mL). Note that some computerized feeding systems may not ‘self clean’ very well, so ongoing monitoring of the cleaning and sanitation procedures, cleanliness of the milk and frequent replacement of the feeding hoses is recommended.
- Milk temperature should be between 95 and 105° F when delivered to calves.
Daily milk allowance
A high plane of nutrition supports growth as well as a strong immune system. Producers are encouraged to feed at least 20% of the weight of the calf (approximately 8 liters per day for a Holstein calf) of a high-quality milk replacer or whole milk. If using a computerized feeder, meal allowances should be ≥ 2L per meal and the daily milk allowance should be ≥ 8L per day.
Do not use an excessively long delay in the ramp up period to reach this peak milk allowance, as this is associated with increased disease risk. A reasonable goal is to be offering calves the full/peak daily allowance by 5 to 7 days of age. A majority of studies indicate that producers will be paid back for this increased investment in milk allowance through healthier calves, improved growth, and improved milk production in the adult cow.
Keep group sizes as small as possible
Studies show increased disease rates when calves are housed in larger groups (greater than 7 to 8 calves per group) as compared to calves housed in smaller groups or housed individually. If producers want to capture the benefits of socialization while minimizing disease risk, pair housing (2 calves per pen) might be an option to consider.
Overcrowding is a significant risk for higher disease rates. It is currently recommended that there be at least 40 ft2 per calf.
Use an all-in all-out system for assembling groups of calves, then emptying and cleaning/sanitizing the pen after the group is weaned. If this is not possible, keep the distribution of ages as narrow as possible, with no more than a 1-week difference in ages among all calves in the group. By having calves of a similar age/size, there will be less risk of bigger calves outcompeting smaller calves, and there will be reduced risk for a disease being passed from older to younger calves, as is frequently seen in continuous flow systems.
Delay introduction to the group until 12 to 14 days of age
Studies report benefits to backgrounding the calf in an individual pen for 12 to 14 days prior to introduction to the group. If introduced at an older age, the calf is quicker to catch on to the new feeding system and will be more able to compete with group mates. One study also reported reduced respiratory disease in calves introduced after 12 days of age. Furthermore, by backgrounding calves for 12 to 14 days you will, by default, reduce your group size and stocking density, which will be a benefit to all.
Excellent air quality is a must for any housing system, both to reduce pathogen burden and to remove moisture.
Clean, dry and comfortable are the hallmarks of a good bedding program. Deep straw to allow nesting and provide insulation is strongly recommended in the winter. Slatted floor systems (or no bedding) are discouraged for calves as this can predispose to chilling, is uncomfortable (calves spend more time standing/less time lying down), and can lead to sometimes permanent joint injuries, infection and lameness.
Daily examination of calves
Conduct daily examination of calves for early detection, diagnosis and treatment of disease. Computerized feeding systems are designed to assist producers in finding suspected sick calves by using software algorithms that monitor for changes in feeding behaviors such as daily milk intake (L/day) or drinking speed (mL/min).
However, research suggests that these algorithms are not always sensitive and may miss detecting many sick calves. As such, while the computer may be an ‘aid’, do not rely solely on the computer to indicate whether a calf is potentially sick. It is important that a trained person evaluate calves daily for signs of illness, as early detection and appropriate diagnosis and treatment will result in a better case outcome.
For more information, please contact Dr. Sandra Godden from the University of Minnesota's College of Veterinary Medicine at 612-625-8177 or by email at email@example.com.