Effects of Haemonchus Contortus in Pen-fed versus Paddock Sheep as Determined by Plasma Cortisol and Insulin-like Growth Factor 1

A reduction in live weight occurred in the pen-fed sheep until they became accustomed to the lucerne pellets. In the pen-fed sheep, but not in the paddock sheep, the effects of a sub-clinical infection of H. contortus were observed to cause a significant but transient decrease in plasma insulin-like growth factor 1 (IGF-1). The reduced plasma IGF-1 concentrations suggest that a further decline in nutritional status occurs in infected sheep, already suffering some nutritional deprivation due to diet alteration.