Many of the herds showed some clean samples and some highly infected. Worm loads among cattle sampled ran as high as 600 eggs per gram of sample. You would think problem animals could easily be identified. The quickest tipoff would be cows with a lack of body condition and rough hair coats, which would result in poorer milking cows and poorer doing, less thrifty calves. The cycle is simple Cattle with adult infestations shed eggs in their manure.
Eggs develop into larvae.
Favorable moisture and temperature in lush grass spread these larvae to grazing cattle and the cycle starts all over again. The larvae must be ingested to complete the cycle. Worms are like weeds Cattle seldom become clinically sick from worm infestations. But a severely infested animal will more quickly exhibit other disease signs when stressed. The most likely loss is the extra production you never see.