Shannon Williams, University of Idaho extension educator, says producers need to know nutritional value of the feed (fall pasture, hay, etc.).
“The important thing is to meet the cow’s nutritional demands so she can keep lactating and continue to have good body condition so she can rebreed on schedule. The fall-calving cow has to breed back during a tough time of year, if you have cold winters,” she says.
You don’t want a cow to come up open because your feeds didn’t quite meet her needs. In a mild climate, feeding fall-calving cows can be much easier than in a cold climate where you must address the challenges of cold stress – providing additional calories so cows can maintain body heat.
“There may be some benefits with a supplement for those calves, as well,” says Williams. This could help provide the extra nutrition calves need for keeping warm in cold weather and take some pressure off the cow for providing it all with milk.
A creep area for the calves or a portable creep when rotating fall-winter pastures should be constructed in a way to keep the feed clean and dry or calves won’t eat it. You need a plan for how you’ll feed those calves, and it needs to be cost-effective.
“You may need to supplement the cows, depending on quality of fall pasture or the hay, and this may mean taking samples for testing.” Most grasses drop dramatically in nutrient levels (especially protein) as they mature and go dormant. Orchardgrass, for instance, may drop from 16 percent protein to 8 percent.
Not all pastures have adequate nutrition for lactating cows at that time of year. Mature native pastures have different nutrient levels than dormant, mature tame grasses, and both may be lower quality than an energy-dense forage like ryegrass or a pasture containing a high proportion of legumes.
“If you seeded a pasture with energy-dense forages or legumes a few seasons ago, it may change over time – due to soils or management. A pasture may have been 50 percent alfalfa a few years ago, and now, it’s down to 10 percent and mostly grass,” says Williams.
“If grazing sudangrass, watch for frost and prussic acid poisoning. If it’s new seeding or resprouted grain with lots of pigweed, be aware of risk for nitrates,” she says.
“Feeding fall-calving cows is not much more complicated than feeding spring-calving cows, but in the fall, it’s the end of the growing season, and you may have to contend with snow, frost and cold weather,” says Williams.
Nutrient needs for lactating cows vary with breed and the individual – whether you have heavy-milking cows or average-milking cows. “As you get farther into winter, it will also make a difference whether cows have adequate shelter and windbreaks.”
Dr. Bart Lardner of University of Saskatchewan always asks ranchers if they can evaluate the cost of putting energy and protein in front of that lactating cow after she calves. Nutritional requirements largely depend on what the winter-feeding program is based on.
He reminds ranchers that a cow has a 100-day “critical period” during her production year. “This includes the 30 days before she calves and 70 days after she calves. This is when we need to pay attention to energy and protein,” he says.
“A lot depends on the forages and how the herd is managed. Many producers are innovative these days. Some still use a lot of harvested feeds, such as various types of hay in bale form in a drylot pen, but many producers use extensive grazing practices. They may be using stockpiled perennials or windrowed annual cereals or bale grazing,” says Lardner.
“Depending on the forage source, we may have to provide supplements. The type of supplement needed depends on where you are. Much of the research in the U.S. shows that protein supplementation is needed, because many forages’ areas are deficient in protein during winter, and we need to feed the rumen bugs.” These rumen microbes need adequate protein to break down the fiber in forage and create energy, heat, etc. during this type of digestion.
“Protein supplementation in a moderate climate is important. In a colder climate, however, with subzero temperatures and deep snow, we find energy deficiency is also a big issue. So we look at supplementation strategies that provide adequate energy as well as protein during those critical days,” Lardner explains.
These cows must be fed a higher quality type of hay or a supplement that contains more energy. The needs for more energy and/or protein might be met just by feeding alfalfa hay, but you have to look at the cost of the hay and/or supplement.
Producers have to find feeds that are cost-effective. “Look around your local area and see what kinds of supplement possibilities are available – for protein and energy. If the cows need more energy, you’d want something that would be similar to barley grain or corn grain.
There is a lot of distiller grain byproduct available, and sometimes it will pencil in a bit lower if you are close to a plant. If not, this type of supplement is out of the question because of the high cost of hauling it very far,” says Lardner. 
PHOTO: Dried distillers grains can make a good supplement for cows if it is cost-effective. Photo by David Bohnert.
Heather Thomas is a freelance writer based in Idaho.
Why calve in the fall?
When you actually calve will be a factor; there are differences in what people consider fall calving. Some calve in September, some calve October or November, and a few calve in August and call it fall calving. Some years, fall calving may be ideal if fall rains stimulate regrowth and there’s green pasture for lactating cows before they start into winter, but other years, the fall and early winter pastures may be dry and lacking in nutrients.
Calving season may be dictated by what works best in your situation. “Some ranchers using public land are calving in the fall, grazing public range pastures with dry cows (weaning calves in spring or early summer before turning out on the range) then bringing cows home in the fall to calve on green pastures or aftermath or regrowth in their hayfields,” says Williams.
One rancher in her region brings cows home off the range in August because of hunting pressure on their allotment – cattle scattered and disrupted by hunters. They changed from spring calving to early fall calving so they could run dry cows on range, bring them home in August to calve, coming off the range before early fall hunts begin.
Each producer must figure out what works best for their own operation, regarding calving season, feeding pregnant and lactating cows, etc. Determining feed costs and expenses compared with what calves are bringing should be part of the picture.
“The rancher who decided to calve in August is giving up a few pounds of weaning weight, but those calves have done well. The reduced labor [calving in August rather than late winter or early spring when cows must be in a barn to calve] is another factor that made fall calving attractive.”
There are pros and cons for every situation. Weigh advantages, disadvantages; feed values and feed costs should be known for your operation. Fall calving often works if the cows can have cost-effective, adequate nutrition for lactation.
It hinges on what you can feed, whether it is adequate and if you’ll need to supplement (and whether the supplement is cost-effective) – and monitoring body condition. Some cows might drop out of a fall-calving program because they are not genetically feed efficient for this kind of situation and don’t breed back.
