“An Open Winter”
by Chris Reinhardt, feedlot specialist
Lack of precipitation during the winter is a double edged sword: moisture is essential for spring grass to come on strong and for water sources to fill; frozen moisture blowing sideways at 35 mph is hard on both man and beast. So although we openly breathe a sigh of relief for every winter day without a blizzard that same lack of snow fall means one more rain we’ll need come spring.
But there is an additional potential hidden pitfall to lack of snow cover: Managerial Overconfidence. Just because we can see grass on the hillsides or crop aftermath in the fields where cows are grazing, doesn’t mean we can let those cows entirely fend for themselves.
The first reality is that, although cows are designed to utilize low quality forages, such as dormant grass and crop residues, they can make much better use of it with appropriate supplementation. For example, a 1,300 lb cow can eat roughly 20 lb of low quality (<7% crude protein) forage without supplementation, and digest roughly 50% of it for a net intake of 10 lb of total digestible nutrients (TDN). If we supplement those same cows with 3 lb of soybean meal or 4.5 lb of distiller’s grains daily, those same cows will consume 24 lb of forage and digest 55% of it for a net intake of 13.2 lb of TDN—that’s a 32% increase! There’s no free lunch in production agriculture, but the returns from protein supplementation on a low quality forage diet is as close as we can get.
The second thing to realize is that just because we can see grass and not a snow bank doesn’t mean that the cows aren’t fighting off the winter cold. For 1,300 lb cows with a good, dry, winter hair coat, the thermoneutral zone is about 30-32°F. That’s the wind chill temperature, not simply air temperature. For every 10° that the effective temperature (wind chill) drops below 32°, the cow’s energy needs increase by 10%. So if the effective temperature drops from 30° to 10°, and feed isn’t in excess, we’ll need to supply an additional 5 lbs of hay. If temperature drops from 30° to 10° below zero, we need to supply an additional 10 lbs of hay.
Finally, know what your cows weigh. Genetics have changed dramatically in the past 20-30 years; cows are bigger and heavier. The average cow in the Angus Association weighs about 1,350 lbs. So unless the bulls siring your replacement heifers have had lower than average yearling weight EPDs, your mature cows probably weight 1,300 lbs too. The downside of underestimating your cows’ weight is that for every 100 lbs you underestimate cow weight, you’ll underfeed the cows by about 1 lb of hay and 0.33 lbs of protein supplement. You’ll save on feed costs in the short run, but cow body condition will slowly slip downward, and cows will be undernourished at calving time, resulting in reduced calf health, greater number of days required to breed back, and reduced breed back percentage. Make a point to weigh a handful of cows at some point when they’re in good body condition. If they’re thin, add 100 lbs per cow to the scale weight to reflect what the cow’s target weight should be.
