Farmscape Article 2935  August 15, 2008

Manitoba swine producers are being advised to exercise additional vigilance this year to avoid the potential consequences  of feeding mycotoxin infected feed grains.

Fusarium head blight is a fungal infection that affects primarily cereal crops, most notably wheat. Weather conditions ideal for the development of the disease were prevalent this year during the most vulnerable stage of crop development resulting in widespread infection of red spring wheat crops in Manitoba.

Widespread Presence of Fusarium Identified
“A lot of the wheat crops are starting to show a lot of fusarium mainly due to the moist conditions we had at flowering,” observes Manitoba Agriculture Food and Rural Initiatives (MAFRI) farm production advisor for southwestern Manitoba Lionel Kaskiw.
“When you look at the head of the wheat it actually has white areas in it which basically are not going to produce viable seed or good quality seed. We’re seeing it pretty much in every wheat field.”

Kaskiw suggests it’s hard to find a field in his region that isn’t infected because conditions were perfect for its development. He expects fusarium to be one of the yield reducers this year.

Fusarium Infected Grain Potentially Toxic to Swine
Fusarium contaminated grain is of particular concern to swine producers. Fusarium graminearum, one of the species common in Manitoba, produces a number of mycotoxins. Deoxynivalenol, or DON, when included in swine rations, tends to cause feed refusal resulting in slower growth. When eaten by pregnant gilts or sows, reproductive performance can be affected. The mycotoxin, Zearalenone (ZEA) is responsible for a range of breeding and reproductive problems including infertility or abortion.

Toxin Mimics Naturally Occurring Hormone
Robyn Harte, a business development specialist swine with MAFRI, explains Zearalenone mimics estrogen.
“This mimicked estrogen can bind with receptor sites and it can interfere with things like return to estrus. If exposure happens while the sow or gilt is pregnant they can have a greater degree of still births so it acts in this negative way by mimicking naturally occurring hormones.”

Harte says, in the case of gilts in the development barn, levels as low as three to five parts per million of Zearalenone can cause the onset of an early estrus without any actual estrus. In sows levels as low as five to ten parts per million will cause reduced litter sizes, you’ll see pseudo-pregnancies, so they won’t actually be pregnant. Animals that are pregnant will produce a reduced number of piglets and you’ll also see a reduction in the weight of each piglet so litter rates are going to be lower. When levels approach 30 to 60 parts per million you see  more in the way of abortions.

Harte adds boars are also negatively affected at that 30 to 60 parts per million range. You see a reduction in the quality of sperm, more abnormal sperm and a loss of libido or eagerness to breed.

Harte notes, for the grower finisher, you’ll see things like rectal and vaginal prolapses and reduced performance. They won’t feel well so they won’t want to eat, so your average daily gains will be negatively impacted as well.

Problems this Year Contrast Previous Years
Concerns over fusarium had recently become somewhat dormant.
“In the last couple of years by the end of June, the beginning of July the tap shut off and we weren’t getting much moisture,” says Kaskiw.
He says that worked in our favor because the disease required moist humid conditions to infect the plants so, the last couple of years, a lot of the fields were doing very well.

“We’re getting back to where we were getting moisture during the flowering time and filling and we’re going to be seeing more concerns about fusarium and probably more talk about fusarium resistant varieties.”
Although we are seeing more fusarium this year than the past couple of years, Kaskiw doesn’t consider the situation to be a disaster.
“I think this year is kind of a check year to show us the disease is out there and can cause a bit of damage.”

Fusarium Presence Not a Guarantee of Toxins
The presence of fusarium in a field doesn’t necessarily mean the grain will become contaminated by mycotoxins or even that yields will be wiped out.
“One of the things about fusarium, it’s going to depend on how early it affects the plant. A lot of times, if it affects the plant early, a lot of those seeds won’t make it into the sample so the levels found in the sample might be low enough that it won’t cause any great discounts.”

Harte recommends mitigating the inclusion of mycotoxins in swine rations any way possible, including sourcing non contaminated grain or grains with very low levels of contamination. She also encourages dilution, mixing contaminated grains with clean grains.
She notes absorbents also will ease the effect of consuming contaminated feed. The absorbent renders the toxins inactive blocking absorption.

Vigilance Recommended
Above all, Harte calls for vigilance.
“If they’re starting to have feed refusal, if you’re starting to have longer weaned to breeding intervals, take a look at your grain and your inclusion rates and perhaps decrease the inclusion rates of the contaminated feedstuffs because it can create a serious negative impact on your production.”
She stresses, “It’s always better to act before it becomes a real problem than after the fact so vigilance would really be my personal recommendation.”

Staff Farmscape.Ca