AIRDRIE, Alta. – Cows need to fit their environment, which is why females grazing in Arizona are different from those seen in Alberta.
Costs go up if cows do not fit the environment, a Cargill beef consultant and grazing specialist told a recent winter feeding seminar sponsored by the Foothills Forage Association.
Bryan McMurry said grazing is the cheapest way to maintain cows, but additional feed is needed to carry them through the winter, especially in Western Canada where there is the risk of extreme weather.
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“Quality determines how much she will eat,” he said. “What she can do and what she will do can be two different things.”
It takes longer for rumen microbes to break down the necessary nutrients in a poorer quality feed. As a result, cows spend more time ruminating and less time grazing.
“She will try to eat her dry matter requirements when grazing. If quality is sufficient, she will eat and then lay down to ruminate.”
He said the average cow tries to do that twice a day.
“The best thing about high quality is you can feed less than she can eat.”
Producers need to understand cow nutrition requirements from weaning to calving to reduce costs and fill nutrient gaps.
The most important nutrients are energy and protein. Cows can receive less than National Research Council recommendations, as long as quality is high. They will eat more poor to average feed to fill themselves up, but they may not be deriving enough of the necessary nutrients for proper maintenance, gestation and health.
The baseline dry matter requirement is two percent of total body weight, but many producers underestimate cows’ weight. Bigger cows have higher feed requirements, depending on the stage of production.
Crude protein requirements for a dry cow that has just weaned a calf are almost half that of a lactating cow. Energy and mineral requirements will also drop but not as much as protein needs.
Energy and protein requirements are relatively flat in the first three months of the dry period, but they increase as the last trimester of pregnancy approaches because of the need to feed the fetus and start producing milk.
“The most critical period for a dairy cow is not when she is lactating, but the 60 days before she calves,” McMurry said.
Beef cows do not have to be managed as precisely, but producers need to be aware of increased feed requirements in the last 60 days.
He recommended blending low quality with better feedstuffs to get cows through a hard winter. Producers should offer the poorer quality feed first.
A feed inventory in the fall is a good place to start. Producers should know what is available, whether it is dormant standing forage, silage, haylage or hay, grain such as barley, corn or wheat or byproducts such as dried distillers grain.
They then need to test the feed for a nutrient inventory, which provides a percentage of nutrient values of what is present as compared to the cow’s requirements. It does not have to be as precise as a feedlot diet.
Supplements are needed if crude protein is less than seven percent. They are flexible and can be offered three times a week to meet requirements. Look for the cheapest, most palatable and safest supplements.
Rumen microbes need the nitrogen found in protein. Cows cannot use energy in the diet if the microbes are not working efficiently to process it.
Cows can get through winter with grass hay, but as the season wears on they could lose condition at a time when they need more nutrition to grow the calf.
Most fetal growth occurs in the last two months, which means cows that aren’t fed enough will give birth to weak, lightweight calves with greater susceptibility to scours.
“In the last two months, she just can’t overcome our lack of management,” McMurry said.
It is a good idea to check body condition score at pregnancy checking time.
Many producers try to fatten up cows in the fall and let them drop weight during the season for calving at a condition score of four or five. On a scale of one to nine, four to five is moderate sized with no ribs showing.
Cattle with low body condition scores are more likely to be open.
Cows that calve in a condition score of three or four have difficulty exhibiting their first heat by 80 days after calving. Cows that calve with a score of five or six tend to go into heat by 55 days after calving, which means they have a better opportunity to maintain a 365 day calving interval.
Cows that calve at a score of seven with considerable flesh and fat have a short postpartum interval, but it is not economical to feed cows to that level.
As well, animals may receive adequate energy but still suffer from mineral deficiencies.
“There are no pastures that I have seen an analysis of anywhere in North America that did not require mineral supplementation,” McMurry said.
These may be deficient in some macro and many micro minerals, so supplements such as selenium, manganese, zinc and copper are needed. Selenium is deficient nearly everywhere on the continent.
“There may be no energy deficiency, but the mineral deficiency is huge,” he said.
Producers should add minerals to the diet and make sure cows eat it. Minerals can be blended with feed or offered free choice.
