CORTISOL AS AN INDICATOR OF SEVERITY OF PARASITIC INFECTIONS OF HAEMONCHUS-CONTORTUS IN LAMBS (OVIS-ARIES)

Two experiments were conducted with lambs to examine the effects of ex perimental infections of Haemonchus contortus on circulating cortisol levels. In both experiments, naive lambs were divided into three group s based on inoculum doses of 0 (control), 2000 (low dose) and 20,000 ( high dose) infective larvae. In experiment 1, the lambs were sampled o nce daily from day 1 post-inoculation (p.i.) until day 39 p.i. Lambs f rom the high-dose group had significantly higher sustained levels of c ortisol throughout the course of the infection than either the low-dos e group or control lambs. In experiment 2, blood was sampled at 30-min intervals for 4 hr on day 21 p.i. The high-dose group also had highes t cortisol levels. The consequences of chronic stress and the resultan t elevated cortisol concentrations potentially could compromise animal health and animal well-being. Copyright (C) 1997 Elsevier Science Inc .