Helminth parasites of economic importance in cattle in New Zealand

Abstract

New Zealand farmers are currently spending about $27.9 million/yr on anthelmintics to control helminth parasites in cattle. Productivity trials carried out over the last 30 years show that the benefit-cost ratio of an effective drench programme is likely to be high, particularly in young animals in their first year, which tend to be very susceptible to infection. In New Zealand, cattle have been recorded as the definitive host of at least 27 nematode species, two trematode species, and one (possibly two) cestode species. Of these, three gastrointestinal nematode species/species complexes, Ostertagia ostertagi/O. lyrata, Trichostrongylus axei, and Cooperia oncophora/C. surnabada are generally considered to be of greatest and most widespread economic importance. In New Zealand, as overseas, bovine ostertagiosis occurs in two clinical forms, referred to as Type I and Type II. Type I ostertagiosis is the normal form of the disease seen in weaner cattle, while Type II ostertagiosis results from the rapid maturation of large burdens of arrested fourth stage larvae of Ostertagia spp., which can accumulate in the stomach wall of yearling and older cattle. While some of the nematode species that have been recorded from cattle were simply incidental infections resulting from cross transmission from different host species (particularly sheep), one species complex, Ostertagia leptospicularis/ kolchida, which is normally considered to be a cervid parasite, is known to cycle readily in young cattle and has been implicated in clinical disease. The liver fluke Fasciola hepatica can be economically significant in cattle under certain local conditions but, while its distribution has increased markedly over the last 20 years, it is still generally considered to be a relatively minor problem in the national sense.

The effect of rotational grazing by either calves, cows, lambs or ewes on the removal of herbage contaminated with gastro‐intestinal parasite larvae around cattle faecal pats

“…We found a similar L 3 reduction for our autumn pats. Our large autumn L 3 peak is typical in New Zealand, with temperatures good for L 3 development and sufficient rainfall for migration onto pasture (Bisset 1994). This allowed one grazing to eliminate the majority of L 3 , but concentrations at the subsequent grazing were still high enough to affect calf performance.…”

Genetic line comparisons and genetic parameters for endoparasite infections and test-day milk production traits

“…A challenge for the farm management in organic farming systems is that medical anthelminthic treatments for adult cattle are strongly restricted. Moreover, an increasing resistance of sheep and cattle nematodes against anthelmintics has been observed (Bisset, 1994;Moll et al, 2000;McMahon et al, 2013).…”

Sire effects on antibodies to nematode parasites in grazing dairy cows

“…Controlling nematode parasites can lead to improved milk production in New Zealand dairy cows (Bisset 1994). The obvious cost of nematode parasitism is in the anthelmintic treatments used (c. NZ$14 million annually; Nielsen 1997), but the real cost also includes the lost production from subclinical parasitism, as quantified in milking cows by Bisset et al (1987a,b).…”

“…Fortunately, this situation has not progressed as far on New Zealand dairy or beef farms (Vermunt et al 1995;McKenna 1996), but there is the potential for drench resistance in cattle, with the expansion of dairy bull beef production (Bisset 1994;McKenna 1996), and with farmers being encouraged to drench in-calf or lactating dairy cows through access to anthelmintic products with nil withholding time.…”

“…The obvious cost of nematode parasitism is in the anthelmintic treatments used (c. NZ$14 million annually; Nielsen 1997), but the real cost also includes the lost production from subclinical parasitism, as quantified in milking cows by Bisset et al (1987a,b). In calves the effects have been quantified in terms of growth rates (Bisset 1994), but the most important effects in calves are likely to be seen in terms of their subsequent milk production, either directly or as a result of failing to conceive.…”