The Wonders of Wool for Calf Warmth
Raising calves in northern Wisconsin is not for the faint of heart. But custom calf raisers Sherry Arnold, partner at Busse’s Barron Acres, says winter is actually the most productive time of the year for 2,700-2,800 preweaned calves they have on feed at any given time.
“If calves have fresh air and are warm, dry, and well-fed, they can handle winter just fine,” shared Arnold. “Wisconsin winters are harsh, but in the summer, we have to fight flies, heat stress, and higher pathogen challenges. We reliably have our best rate of gain in the winter months.”
Arnold’s “secret weapon” in keeping calves warm is consistent use of calf jackets for about half the year, starting in November – but not just any calf jackets. The only jackets she will use are made of 70% wool.
“I believe strongly in the benefits of calf jackets, and I’ve tried virtually every material available, including ThinsulateTM, fleece, and quilted fabrics,” said Arnold. “I’ve never found anything that can match the properties of the wool jackets, which we’ve been using for more than 20 years.”
She said there’s no better source than Mother Nature for a material that naturally protects animals, and grows with them. Busse’s Barron Acres custom raises about 14,000 calves annually from 19 different dairies, and in the winter, every calf gets a wool jacket the day it arrives, which usually is within a day or two of birth.
“We’ve tried different timing configurations with the jackets, like using them for only 4 weeks. But it really made little sense to stress a month-old calf like that in the middle of winter,” Arnold stated. “So as long as the weather is cold, we leave them on for the full 8 weeks while the calves are on milk. Unlike other fabrics, wool will stretch as the calf grows, so we never have to worry about the jackets confining them or causing sores.”
Wool also “breathes” with the animal, and has moisture-wicking properties that other fabrics don’t. Arnold said it can be dangerous to put other calf jackets on damp or wet calves, but wool actually will draw the moisture out of the calf’s haircoat and dissipate it while the calf stays warm. And in warm weather swings, condensation under some jackets can be a concern, but not with wool.
Arnold also appreciates the design of her preferred brand, Woolover calf jackets, because it provides about 30% more animal coverage than others. “This jacket covers the heart and lungs, which are the critical areas we want to protect,” she noted.
A few years ago, Arnold conducted a trial to measure the impact of the jackets on calf performance. Her study of 100 bull calves showed that the addition of the wool jackets resulted in an increase in average daily gain of about .78 pounds per head, or approximately 47 pounds per head total by weaning.
“Because the jackets help the calves retain their body heat, they can convert calories into gain instead of just staying warm. We can justify the cost of a jacket for every calf based on the gain advantage alone,” noted Arnold. “And that doesn’t even take into account the savings in animal performance, drug costs, and labor that we would incur with sick calves. One shot of antibiotic can cost almost as much as a single calf jacket.”
The Busse crew disposes of jackets that are worn for a full 8 weeks, but if they are only worn for half a season in the spring, they do launder and store them for another wearing. They’ve found the best cleaning method is power-washing them with hot water, then hanging them to fully dry.
Those used jackets may be stretched a bit from calf growth. Arnold said they will be the first ones used in the fall, when a bit of a loose fit is not as critical. “But in the dead of winter, I want a snug-fitting jacket on every calf,” she declared.
In its winter offense strategy, Busse’s Barron Acres also feeds a fat supplement in addition to its standard milk replacer ration, and is generous with straw bedding for calves, all of which are reared in outdoor hutches. Their fastidious efforts consistently produce average daily gains of 1.4-1.8 pounds. This allows them to easily achieve their goal of doubling every calf’s birth weight by weaning, while achieving an impressive annual mortality rate of just 4-6%, which includes voluntary culls.
Because the wool jackets are made in New Zealand, timely supply was sometimes a challenge for Busse’s Barron Acres, which uses about 5,000 jackets annually. For that reason, the farm is now an agent/warehousing site for the manufacturer, but makes no margin on the products. “I think we’re the largest single user in the U.S.,” said Arnold. “Becoming an agent allows us to have a huge container and a ready supply on hand at all times.
“It’s so much more rewarding to raise healthy calves, and there is growing research that shows how calfhood health relates to longevity and productivity in the milking herd,” she added. “Using wool calf jackets is one of our fundamental tools for returning healthy, productive calves back to our clients.”
