Mycotoxins have been shown to be detrimental to animal health. In most species, young animals are more sensitive than mature animals to the effects of mycotoxins. However, dairy cattle may be the exception to the rule, says Duarte Diaz, ruminant research manager at Novus International. Due to the intense demands of lactation and the large quantities of feed consumed by lactating cattle, it may be possible that calves and heifers are slightly more resistant to mycotoxins than lactating cows, says Diaz. But don't discount mycotoxins; they should always be considered a causative factor when unidentified problems exist in calves. Some of the common clinical signs associated with a mycotoxicosis in both young and adult cattle include intermittent diarrhea, sometimes with bloody or dark manure, reduced feed intake, feed refusal unthriftiness, rough hair coat, undernourished appearance, subnormal production, increased abortions or embryonic mortalities, silent heats, irregular estrous cycles, expression of estrus in pregnant cows, and decreased conception rates. Mycotoxins should be considered as a causative factor in calves and heifers when animals are underperforming and/or are unhealthy.

Read Diaz's paper from the 2010 Dairy Calf and Heifer Conference.