After a wet summer Manitoba cattle producers are faced with the reality of keeping animals healthy on less-than-ideal feed sources.
It’s possible, but Juanita Kopp, a provincial livestock specialist, says producers do need to be aware of the risks and take steps to manage them.
“This is one of the topics I get a lot of questions on,” Kopp said in a recent interview. “I know that there is mouldy feeds fed every year in this province, and generally, you might not see any issues, but the biggest issue you would see, would be losses in production.”
Mould growth can reduce the value of the feed and the productivity of livestock, because it makes the feed less palatable to cattle.
“Of course, if they don’t like to eat it you are going to have reduced intake and therefore lower production and growth,” Kopp said.
As mould spores grow they also destroy the vitamins in feed, particularly vitamins A, D, E and K. Growing spores also have the chance of producing harmful mycotoxins.
“Mycotoxin production can be developed in almost any feedstuff during the growing season, harvest and during storage,” Kopp said. “Grains tend to receive the most attention but byproduct feeds, protein concentrates, finished feeds, oilseeds, wet brewers grains, food waste and forages may also contain mycotoxins.”
As the mould or fungal species grow they metabolize and produce secondary metabolites, mycotoxins. These can be extremely potent and produce effects with even low levels of exposure, Kopp said.
“Many commonly detected mycotoxins are produced in the field prior to harvest, so there is not much you can do to prevent it. But, of course storage and harvesting at the appropriate moisture, especially with silages, can help to reduce mould production,” Kopp said.
Mycotoxins can cause mycotoxin poisoning in livestock, which represses the animal’s immune system and can cause lack of response to medications and failure of vaccine programs.
“Mycotoxins may also cause diarrhea, intestinal infections, reduced production, lower fertility, lethargy and increased morbidity. It can also impact the enzymes, how they are produced and how they function,” Kopp said. “With that we can see some suppression of the immune system, which predisposes our animals to diseases and may increase milk somatic cell count when looking at dairy cows.”
Mould growth will also exacerbate dust, which if inhaled can cause fungal pneumonia. Mouldy hay also presents a problem for producers, as the mould spores can be inhaled and cause farmer’s lung.
Mould requires oxygen, heat, moisture and nutrients in order to grow. Once moisture levels reach 15 per cent, mould has a chance to grow and it will grow most rapidly at the 24° to 32° mark.
“If we eliminate oxygen or moisture then we can maintain the feed for an extended period of time,” Kopp said.
If you have concerns over the level of mould in your feed, Kopp highly recommends getting a feed test in order to get a better understanding if it may be acceptable for use.
She adds, that determining if feed is still acceptable is a complex situation which requires a case-by-case analysis.
“Under 500,000 spores per gram is a relatively low count and should be acceptable for feed. When we get over a million spores per gram, that is when we start to discount the energy, so feed with caution,” Kopp said.
In most cases, the best thing to do with mouldy feed is to compost, dispose of, or dilute it with ‘clean’ feeds.
“Mixing with other ‘clean’ feed is probably the best way to go, but I would still observe the animals for any changes in behaviour,” Kopp said. “Cattle are generally less sensitive to the moulds and mycotoxins than pigs, horses and chickens because they can detoxify and transform to other metabolites that are less harmful, but they are nevertheless susceptible to the negative effects of mould and mycotoxins in feed.”
If you do plan to use contaminated feeds, Kopp says they are best fed to older replacement cattle or cows that are late in lactation.
“We want to limit the amounts of mouldy feeds to the more sensitive animals in our herd, that being pregnant cows or high-producing cattle in terms of dairy cattle, and younger calves, as they are a lot more sensitive to mould,” Kopp said.
Kopp recommends looking into the Prairie Diagnostics Service’s feed tests, which also offers mycotoxin and ergot toxin screens, or inquiring with your local Manitoba Agriculture office.