Housing is an ideal time to treat cattle for parasites and this can make a significant difference to productivity levels. So says Boehringer Ingelheim Animal Health vet Sioned Timothy, who met with Rachael Porter to explain that parasitic infections are one of the most common reasons for poor performance and economic loss in cattle farming, even in the absence of clinical disease.
Reduced feed intake, weight gain and impaired fertility can be attributed to a parasitic burden in growing cattle. And in replacement heifers the impact of parasites can extend into their first lactation, with reduced milk production.
“Sustainable parasite control strategies are increasingly important for the production of healthy heifers,” says Sioned. “Appropriate treatments will help to ensure that they grow quickly, to their full genetic potential.”
To achieve an average age at first calving of 24 months, heifers must reach approximately 60 per cent of mature weight by 14 months of age. This requires an average daily weight gain of between 0.7kg and 0.8kg from weaning and bulling.
“Heifers have high nutrient requirements as they grow and prepare for calving, and a heavy parasite burden will draw on these resources,” she adds. “This will reduce the nutrients available for growth and slow the time the heifers take to reach their mature weight and become ready to conceive.”
In strategically-wormed heifers, studies have shown increased mammary development and earlier onset of puberty, compared to untreated animals. “So monitoring heifer performance and diagnosing parasitic infections is important,” says Sioned.
Before considering which anthelmintic treatment to use, she adds that it is worth considering the performance of the stock during the grazing season, and how it compared with expectations or targets. “Growth rates of young stock in their first and second grazing season are useful indicators of effective parasite control.”
She explains that losses in liveweight gain due to poor parasite control during a heifer’s first grazing season will not be recouped during the second year at grass. “Affected animals will not catch up, and this will impact on their ability to meet important growth milestones, which could result in an increased age at first calving. Monitoring growth rates throughout the year will help to identify individuals that may require anthelmintic treatment.”
Removing parasites such as gutworms and liver fluke at housing will help to ensure heifers are turned out parasite-free in the spring. This helps to reduce pasture contamination at turnout, thereby lessening parasitic infection in the next grazing season.
A targeted approach to parasite treatments at housing increases the sustainability of anthelmintic control and reduces the selection for resistant parasites.
“For this approach to be effective, producers must be able to identify individual cattle that are likely to have a parasite burden. This can be achieved through weight records and targets, or diagnostic testing, such as faecal egg counts,” says Sioned.
“Alternatively, a strategic approach should identify groups of cattle for treatment based on a number of risk factors, including farm history, grazing practice during the summer, anthelmintic treatments while at grass, and any clinical signs of disease.” And the type of parasites likely to be present at housing should also guide anthelmintic product selection.
“While the important gutworm species, Ostertagia ostertagi and Cooperia oncophora, are often both present at this time of year, their sensitivity to anthelmintics does vary – so ask your animal health advisor for guidance,” she says.
Some combination treatments offer convenience by enabling the removal of a wider range of parasites, such as gutworms and liver fluke.
“Resistance to the flukicide triclabendazole is an emerging issue in the sheep and cattle industries. So care should be taken to preserve it for use in sheep, where there is no other alternative for treatment of acute fluke disease.”
Alternative treatments for fluke in cattle include those containing closantel, clorsulon or nitroxynil. These treatments may need repeating at the appropriate time after the initial housing dose to ensure that all juvenile and adult fluke are removed and cattle are turned out fluke free.
Dairy cows and heifers in calf have more restricted options for liver fluke control due to milk withdrawal periods. Advice should be taken from an animal health advisor.
Finally, consider external parasites such as mites and lice, and ensure your chosen housing treatment provides adequate control. Warm cattle sheds can provide the ideal environment for the multiplication and spread of these parasites which cause itching and welfare issues, and can contribute to reduced performance through stress.