Nematode parasites in young cattle: what role for unexpected species?

The parasite burden in young beef calves was investigated to determine the timing and prevalence of sheep parasites in mixed grazing systems. This study was conducted in two parts, firstly regular sampling of cohorts of calves from three farms over a year, and secondly surveying groups of calves prior to weaning across the upper north island of New Zealand. For both trials faecal samples were submitted to the laboratory where they were assessed for faecal egg count and cultured to determine parasite genus and species using microscopic and molecular methodologies. The results indicated that species normally associated with sheep were common and often present as a significant proportion (up to 80%) of the larvae recovered from faeces collected from calves prior to weaning. Of these the most common species were Cooperia curticei and Haemonchus contortus. H. contortus was very common and often as a significant proportion (≤70%) of the total larvae cultured. After calves had been weaned and administered first anthelmintic treatments these species largely disappeared from the faecal cultures. The implications of having sheep parasite species present when undertaking anthelmintic testing in-vitro and in-vivo in calves must be considered. Farmers and veterinarians may also be well advised to consider pre weaning calves as a possible source of contamination when developing their parasite/Haemonchus control plans for sheep.