a1 Department of Zoology, University of Edinburgh.
From the study of the worm egg output of nearly fifteen hundred sheep on many hill farms in Scotland it has been shown that:-
(i) Worm egg output in ewes and gimmers is lowest in early winter and highest in spring and early summer; this is followed by a marked decrease towards the winter months.
(ii) Generally in ewe hoggs the worm egg output is the same as that in older sheep, but shows greater variability; on occasion the spring peak may be absent.
(iii) The level of worm egg output of hoggs is generally higher than that of older sheep, and in this respect gimmers tend to fall between hoggs and ewes.
(iv) Weather conditions may have an influence on the height and duration of the spring peak of worm egg production.