Beware salvaging weather-stressed and damaged crops for feed as nitrate accumulation could have dire health consequences for ruminant livestock, experts say.
“Stress such as drought or hail can cause a plant to accumulate nitrates,” explains Trevor Lennox, Saskatchewan Agriculture’s range management extension specialist.
Hail and dry, windy conditions have recently caused crop damage in parts of Saskatchewan and Alberta.
Alberta Ag reports that recent hail storms in the province severely damaged crops, but they could still have value as a feed source.
Caution, however, should be exercised when salvaging damaged oilseed, cereal or hay crops, the department warns.
Ruminants
Normally, rumen animals like cattle, sheep and goats convert the nitrates in forage to nitrite, which is then converted to ammonia and used by rumen microbes to make protein, Manitoba Agriculture explains.
But when nitrate converts to nitrite faster than nitrite converts to ammonia, nitrite accumulates and is absorbed into the bloodstream. There, it binds to hemoglobin and thereby reduces the oxygen carrying capacity of the blood and puts animals at risk of suffocation.
“You’ll see a lot of laboured breathing, going off feed,” says University of Saskatchewan professor Bart Lardner.
Not all ruminants are at equal risk, and cattle face the greatest threat.
Nitrate poisoning can also have serious repercussions for unborn calves.
Prevention
Barry Yaremcio, Alberta’s beef and forage specialist says nitrate concentrations peak about four days after plant injury, and if the plants recover and begin growing again, nitrate levels can return to normal 12 to 14 days later.
Farmers who suspect nitrates in their feed source can send a feed sample to a feed testing lab, and for around $20, they’ll identify any potential issues, Sask Ag’s Lennox says.
“If a feed test should indicate high nitrates, in most cases the feed can still be used, but will need to be mixed with another feed source to reduce the nitrate concentration,” Lennox says. “This should be done in consultation with a livestock nutritionist.”
Also, if a feed is made into silage, the ensiling process can help reduce nitrate levels in the feed, Lennox adds.
Source : fcc