Don’t Count on Cold to Kill Parasites

Despite the harsh winter, make managing parasites a priority this spring
Record-breaking snowfall and extremely cold temperatures have cow/calf producers excited for spring and all things that go with it: lush, green pastures; growing calves; and healthy cows. While winter may have taken its toll on many things, resilient parasites have proven to survive even the coldest of winters.
Ridding pastures of parasites is not simple during a long winter — they simply overwinter in cattle or pastures. In fact, studies demonstrate that infective larvae were able to survive on pastures during winter months.1,2
“If parasites didn’t survive the winter, we would never have summer parasites to worry about,” said Gary Sides, PhD, Zoetis Cattle Technical Services. “It is important for producers from all geographies to implement a spring deworming program to help give cows a chance to rebound from the tough winter, be productive during calving and, ultimately, be ready for the next breeding season.”
Controlling parasites in cattle is not just beneficial for an animal’s immune system3 — there are performance advantages as well. It’s estimated that internal parasites cost the cattle industry about $3 billion each year in lost weight gains, poor feed conversion and increased disease.4 Since parasites also can suppress appetites and limit absorption of nutrients5 — ultimately reducing feed efficiency and gain — it’s important to have a deworming plan in place this spring.
“Coming off of a long winter, cows are in tougher shape and do not have any spare nutrients to fight off parasites,” Dr. Sides explained. “Spring is the most critical season in the cow’s life, and with cattle prices at all-time highs, we need to take advantage of every opportunity to keep them in shape, including deworming at branding or turnout.”
Internal parasites, such as Ostertagia ostertagi or the brown stomach worm, can cause significant losses because of their impact on an animal’s health, reproduction, growth and productivity. For cows, it’s important to maintain good body condition and keep them ready for the next breeding season. For calves, every deworming offers the opportunity for significant improvement in productivity.6
“Parasites require grass and cattle to complete their life cycle,” Dr. Sides continued. “Therefore, you can be almost certain that cattle on grass are infected with parasites. Many different internal parasites can cause problems, but the brown stomach worm may be the most damaging internal parasite in cattle.
To help protect cattle against economically harmful parasites such as the brown stomach worm, Dr. Sides recommends using a broad-spectrum dewormer. DECTOMAX® 1% Injectable or DECTOMAX Pour-On control Ostertagia ostertagi infections and protect from reinfection for up to 21 days and is safe for use in pregnant cows, newborn calves and bulls. In the Gulf States and West Coast where liver flukes are a concern, VALBAZEN® provides comprehensive protection against the most damaging parasites.
“Fighting parasites that have overwintered on pastures is a simple, low-cost process and something every cow/calf producer should take advantage of during branding or turnout,” Dr. Sides explained. “By combining effective products with the expertise of their local veterinarians, producers can easily develop an effective parasite control program that best suits their herd and geography.”
DECTOMAX Injectable has a 35-day pre-slaughter withdrawal period. DECTOMAX Pour-On has a 45-day pre-slaughter withdrawal period. Do not use in female dairy cattle 20 months of age or older. Do not use in calves to be processed for veal.  DECTOMAX has been developed specifically for cattle and swine. Use in dogs may result in fatalities.
Cattle must not be slaughtered within 27 days after the last treatment with VALBAZEN.  Do not use in female dairy cattle of breeding age. Do not administer to female cattle during the first 45 days of pregnancy or for 45 days after removal of bulls.
About Zoetis
Zoetis (zō-EH-tis) is the leading animal health company, dedicated to supporting its customers and their businesses. Building on more than 60 years of experience in animal health, Zoetis discovers, develops, manufactures and markets veterinary vaccines and medicines, complemented by diagnostic products and genetic tests and supported by a range of services. In 2013, the company generated annual revenues of $4.6 billion. With approximately 9,800 employees worldwide at the beginning of 2014, Zoetis has a local presence in approximately 70 countries, including 28 manufacturing facilities in 11 countries. Its products serve veterinarians, livestock producers and people who raise and care for farm and companion animals in 120 countries. For more information, visit
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1 Tritschler, J. Internal Parasite Control in Grazing Ruminants. Virginia State University. Available at: Accessed March 18, 2014.
2 Smith, HJ and Archibald, R. On the Survival of Overwintering Bovine Gastrointestinal Nematode Larvae During the Subsequent Grazing Season. Can J Comp Med. Jan 1969; 33(1): 44–47. Available at: Accessed March 18, 2014.
3 Gasbarre LC, Rew RS. Immune response in nematode infected cattle following Dectomax® treatment. June 2002.
4 Bagley C, Healey MC, Hansen D. Beef Cattle Handbook: Internal parasites in cattle. Available at: Accessed March 9, 2014.
5 Corwin RM, Randle RF. Common internal parasites of cattle. Available at: Accessed March 9, 2014.
6 Smith RA, Rogers KC, Huse S, et al. Pasture deworming and (or) subsequent feedlot deworming with fenbendazole. I. Effects on grazing performance, feedlot performance and carcass traits of yearling steers. Bovine Practitioner 2000;34(2):104-114.



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