Parasitic infestations with worms and liver fluke cost the Australian livestock industry millions of dollars per annum. In the dairy cattle sector, the impacts are a result of reduced milk production, lower fertility, as well as the costs associated with control measures and treatments. Coinfections with worms and fluke have an additive effect on reducing milk production1. Read on to understand how this could be impacting the performance of your herd.
There are a few common gastrointestinal worms that can cause problems in dairy cattle, including small brown stomach worm, barber’s pole worm, nodule worm and small intestinal worm. The small brown stomach worm (Ostertagia ostertagi) is arguably the most significant. In young cattle it causes loss of appetite, weight loss and watery diarrhoea. In adult cattle, the signs are less obvious, as inhibited larvae induce a strong immune response diverting energy away from producing milk, which can result in a drop in milk production of up to 0.7 - 1.1kg/cow/day2. A national bulk milk tank survey of Australian dairies reported that 92% of all farms tested had small brown stomach worm burdens high enough to be causing production losses3.
Liver fluke (Fasciola hepatica) infects the liver and bile ducts of many mammals including cattle, sheep, and humans. It often goes undiagnosed in cattle because infected animals don’t always show obvious clinical signs. Young cattle are most susceptible to disease and may show signs of failure to thrive, jaundice, anaemia or even death in severe cases. In adult dairy cattle liver fluke can reduce milk production by approximately 4-30%, and also lower herd fertility4. The same national bulk milk tank survey of Australian dairies (referred to above) reported that 38% of all farms tested had moderate to high fluke burdens, indicating that significant milk production losses were likely3. Similarly, other studies have reported prevalence rates of 31-98% in Victoria and up to 50% in Queensland4.
Diagnosing worms and fluke in adult dairy cattle is challenging. Worm and fluke eggs may only be shed intermittently in small numbers, making faecal egg counts less reliable compared to young cattle. For small brown stomach worm, 92% of the Australian dairy herds tested had burdens indicative of production losses3. For fluke, there are specific tests available for blood, faecal or milk samples – seek advice from your local health advisor to plan an appropriate testing program for your herd.
Best practice management involves a combination of pasture management and strategic treatments. On most properties, ‘flukey’ pastures are isolated to certain areas on the farm where they can be managed or even fenced off in heavy fluke risk seasons6.
Strategic treatments at key times of the year should be timed to reduce the number of worms and liver fluke in cattle, as well as the number of larvae and fluke cysts on pastures. Depending on the severity of the problem in your area, two to four treatments may be required for annual management5. Treatments should align with seasonal variations in parasite populations and the lactation cycle of the herd.
There are many options available for treating worms and fluke, however, treatment of lactating dairy cattle is challenging because of milk withhold restrictions for many flukicide products, such as those containing triclabendazole. A treatment such as IVOMEC® Plus, containing ivermectin and clorsulon, is effective against adult and immature stages of small brown stomach worm as well as adult liver fluke and, with no milk withhold period, is an ideal choice during lactation.
With strategically timed treatments and pasture management, the impact of worm and liver fluke infection on your herd can be minimised to help protect milk production. Speak to your local animal health advisor to determine the most appropriate management plan for your area.
*See product label for full claim details and directions for use. IVOMEC® is a registered trademark of the Boehringer Ingelheim Group.