Abstract

A major factor in the reduction of growth in parasitized lambs is the depression in food intake by a mechanism not yet understood. Investigation of the pattern of eating has shown that parasitized lambs have a lower (35%) cumulative intake, especially within the first hour of feeding, which return to a control level on drenching. The importance of two factors which may moderate intake depression, the activity of ventromedial hypothalamus (VMH) and elevated cholecystokinin (CCK), were investigated. Four animals with intake depression (approximately 40% P<0.05) as a result of continuous infection with 4000 T.colubriformis per day for 12 weeks together with 4 control animals received, in a replicated latin square design 0, 1, 2 and 4ml i.v. of a compound (brotizolam) used to block the satiety effect at the VMH. Intake increased (P<0.05) within the first hour of feeding of both parasitized and control animals (approximately 2.6 and 1.9 times, respectively). Four similarly infected and 4 control lambs were given varying doses of a potent antagonist of peripheral CCK action without effect on food intake. These results suggest that depression of food intake in parasitized lambs appears to involve central satiety signals and not peripheral CCK.

DW, Bullock

Proceedings of the New Zealand Society of Animal Production, Volume 50, , 191-196, 1990