New research at the Atlantic Veterinary College at the University of Prince Edward Island reveals that adult dairy cattle carry significant internal parasite loads — significant enough to warrant treatment.

Although long thought to be more of a concern for first-calf heifers on pasture, this study found that parasites afflict adult cows too, even those in confinement situations. The researchers discovered that adult animals studied carried a significant load of Ostertagia. This was true for Canadian cattle, as well as those in replicated experiments in Virginia and Minnesota.

Treatment with deworming products resulted in an average increase of 2 pounds of milk per day. However, cows that carried a heavier parasite burden responded with more milk — some greater than 6 pounds per day.