Testing your feed should top your to-do list this fall and winter.
“Get that crop tested,” said Bart Lardner, a University of Saskatchewan professor who holds a research chair in cow-calf and forage systems.
“Know what you’re starting with and know what you’re dealing with in terms of energy density, protein density, and anti-quality factors like nitrates.”
Drought-stressed plants accumulate nitrates, and high levels can be toxic — even deadly — to ruminants such as cattle. So knowing the level of nitrates in your feed is a good place to start, Lardner said during a Beef Cattle Research Council webinar on July 29.
“Nitrates are on everybody’s minds during a drought,” he said. “With the drought situation, the plants are accumulating nitrates, so it would be wise to know the level of nutrients and anti-quality factors from a feed test.”
Generally, nitrate issues appear in annual forage sources such as oats and barley, and those levels can be tested while the crop is still standing.
“You just go out, walk through that field, grab 20 or 25 samples, composite that into a sample bag, and then send it off,” said Lardner, adding a representative sample is a must.
“Throughout that field, the level of nitrates are going to vary tremendously. So what you’re doing when you’re taking a sample is you’re doing your best to try and get an adequate level of the density of those nitrates.”
And if the sample comes back at levels between 0.5 and 1.0 per cent nitrate, you’ll need to monitor and manage the ration to reduce the risk of nitrate poisoning.
“If you’re feeding something and then go to a high-nitrate diet, it’s a shock,” said Lardner. “So certainly allow that adaptation period — seven to 10 days — and increase that level of high-nitrate feed over that time period.”
The best way to do that is to reduce the amount of high-nitrate feed in the ration to one-third (and no more than half).
“Dilute, dilute, dilute,” said Lardner. “If you can dilute it with some supplemental fibrous-type forage, whether it’s straight hay or rolling out some straw, that would certainly allow you to stretch it out.”
But there’s a balancing act when incorporating higher levels of straw into a ration, said John McKinnon, beef industry research chair at the University of Saskatchewan.
“The biggest factor you have to remember is that straw is a high-fibre, poorly digestible feedstuff,” McKinnon said during the webinar. “It’s low in protein. It’s low in energy. It’s low in minerals. It’s low in vitamins.
“So whenever you’re going to feed a straw-based diet, you always have to remember that you have to supplement additional nutrients with it.”
When it comes to straw, McKinnon typically feeds between 1.25 to 1.5 per cent of the animal’s body weight.
“So if we look at a 1,400 pound cow, for example, that’s probably anywhere around 18 to 21 pounds of straw. In terms of her total intake, she’s probably around two and 2.25 per cent of body weight — anywhere between 28 to 32 pounds of total ration.”
To make up the difference between the roughly 20 pounds of straw and the roughly 30 pounds of total intake, you’ll need to supplement for protein and energy — and “that’s primarily going to be grain.”
“When you’re feeding that amount of straw, you have to start looking at feeding 10 to 12 pounds of barley and perhaps a little bit of protein with it as well,” said McKinnon. “You have to make sure that straw is going to be adequately fermented in the rumen.”
That will be particularly important this year, he added.
“When you start to look at wintering beef cows, their diet is primarily forage on a regular basis, and when we’re into a situation like we’re dealing with potentially this fall where a lot of these forage supplies are going to be in short supply, we’re going to have to feed more grain to compensate for that lack of forage,” he said, adding that will increase the risk of digestive problems.
Again, it will be important to transition cattle slowly to a diet that’s higher in grain to avoid that, he said.
“When you start feeding that level of grain, you have to start to think about the fact that you’re almost feeding a feedlot ration at that point and there’s going to be issues adapting those cows to that level of grain feeding,” said McKinnon.
“The potential for acidosis is there, so you want to make sure those cattle are brought up on that high grain on a gradual basis.”
But ultimately, the ration you feed will need to be tailored to your cattle to get the best performance out of them, and that’s where feed testing comes in.
“There’s a wide variety of feed products out there, and you need to know the nutrient content of the products you’re dealing with,” said McKinnon. “Once you know that, you really need to look at the different classes of cattle that you’re feeding and the performance expectations that you have for them.”
The Beef Cattle Research Council has an online tool for evaluating feed testing results to determine if the feed is adequate as is or if it needs to be supplemented. To use the tool or to learn more about feed testing, visit www.beefresearch.ca and search ‘feed test results.’
For more content related to drought management visit The Dry Times, where you can find a collection of stories from our family of publications as well as links to external resources to support your decisions through these difficult times.