A study of subclinical worm infestation in sheep: part III. The effect on wool production

1. The results of five experiments, comparing the wool production of worm free and infected sheep, are described. 2. Worm-free sheep produced (a) 12·0–38·8% higher total fleece weights and (b) 17·2–43·2% more clean, dry wool per unit area than infected sheep. None of the infestations was higher than occurs naturally in the field, but the greatest effects were associated with a low level of nutrition. 3. It is suggested that the precise effect of worm infestation on wool production will depend upon the age of the host when first infected, the size of the infestation and the rate of wool growth at the time when the infestation is at maximum.