Worm burden of cattle gastro-intestinal nematodes in farmed red deer.

Abstract

Due to the increase in anthelmintic resistance, new ways of controlling gastrointestinal nematodes (GIN) are being researched. Multispecies grazing in New Zealand could be an aid in reducing and controlling GIN, The aim of this study was to investigate the establishment rate of cattle GIN in deer. A mixed culture of cattle infective larvae were obtained from naturally infected cattle. A challenge dose was given intra-ruminally via stomach tube to cattle (n=5) and deer (n=5) containing Haemonchus contortus, Ostertagia ostertagi Trichostrongylus spp., and Cooperia spp.. The challenge dose was adjusted for the mean weight of the two hosts and was given at 0.4 ml/kg: consequently the cattle received 50 ml and the deer 15 ml. After four weeks the abomasums, small intestines and large intestines were collected. The worm burden was determined for each animal and organ. The worm burden Ostertagia ostertagi was significantly lower in the deer than in the cattle (1.9 per ml of challenge dose vs. 82.0/ml; p < 0.05). The worm burden Cooperia oncophora was also significantly lower in the deer than in the cattle (5.9/ml vs. 460.3/ml; p < 0.05). The worm burdens of Haemonchus contortus, Trichostrongylus axei and Trichostrongylus colubriformis were not significantly different in the deer than in the cattle (17.7/ml vs. 41.4/ml, 65.9/ml vs. 86.9/ml, and 0.6/ml vs. 1.6/ml, respectively). These findings indicate that the two most prevalent species in cattle in New Zealand O. ostertagi and C. oncophora are not a risk to establish a significant worm burden in deer after transmission from cattle. The burdens of H. contortus and T. axei in both hosts indicate they are as much a risk for deer as for cattle and may cross infect. There were too few C. punctata, T. colubriformis and C. curticei to make comparisons.