Trichostrongylosis and wool growth. 1. Feed digestibility and mineral absorption in infected sheep

Subclinical infection of sheep with Trichostrongylus colubriformis resulted in reductions in the apparent digestibilities of nitrogen, organic matter, and dry matter; apparent digestibility of nitrogen was affected to the greatest extent. Net absorption of phosphorus was similar in infected and non-infected sheep, but calcium absorption in the infected sheep was only one tenth that of the non-infected controls. Wool growth was reduced by 17 per cent in the infected group, and those sheep that displayed resistance to the infection tended to grow less wool. The infected sheep produced 0.36 g wool per g nitrogen apparently absorbed, compared with 0.46 g wool per g nitrogen apparently absorbed by the non-infected sheep, which suggests that the depression of wool growth in infected sheep may be attributed to differences in their post-absorptive protein metabolism.