November 16, 2015

Dairy herds facing significant mycotoxin risk this winter: AB Vista

With the corn harvest delayed across much of the UK this autumn, the threat of mycotoxins could get even higher than usual, Dr Derek McIlmoyle, AB Vista's technical director for Great Britain and Ireland, warned.

Combined with higher risk of sub-acute ruminal acidosis (SARA) from low dry matter, acidic grass silages and increased feeding of cheap cereals, dairy herds could be facing a 'perfect storm' of mycotoxin risk this winter.

"SARA significantly increases the threat posed by mycotoxins by reducing rumen microbes' ability to deactivate certain mycotoxins and easing mycotoxin passage into the blood by damaging the rumen wall," Dr McIlmoyle explained.

"Corn silages are highly susceptible to mycotoxin contamination, particularly from the Fusarium moulds that grow on the crop pre-harvest. With harvest delayed this year, there's been a much greater opportunity for mould growth and mycotoxin production."

A 2014-15 survey across the south west of England found that even in a 'normal' year, 90% of corn samples tested positive for mycotoxins, with those containing the extremely damaging deoxynivalenol (DON) and 54% of samples contaminated with zearalenone (ZON).

According to Dr McIlmoyle, the impact on cows can be substantial, including reduced milk yield and quality, declining body condition, poor fertility and rising health issues like lameness and mastitis.

"If a problem is suspected, it's often more cost-effective to simply feed a ruminant-specific mycotoxin de-activator and monitor the response, rather than go to the expense of testing forage samples," Dr McIlmoyle added.

"A 2-3 litre/cow/day improvement within 3-4 weeks of adding a de-activator like Ultrasorb is indicative that the mycotoxin load was hurting performance."