Roundworms May Be Weighing Down Your Beef Herd 

Assess the risk of internal parasites in your pasture to improve weaning weights and reproductive performance 


DULUTH, Ga.— Roundworm populations cause a great deal of irritation to a cow’s stomach, often leading to suppressed appetite, reduced feed intake and a negative impact on overall herd performance.1


“Internal parasites are not as top-of-mind as external parasites, likely because they leave no visible impacts,” said Joe Gillespie, DVM, Boehringer Ingelheim. “However, roundworms can significantly impact herd profitability, and are more prevalent than many producers may realize.”


The need to control internal parasites will exist for as long as cattle are grazing pastures. The following considerations can help producers assess the risk of parasites and determine an appropriate deworming protocol for their beef herd: 


1. Location

Parasite risk level can vary, depending on your farm’s geographical location. In the northern part of the United States, cattle on grass are typically exposed to internal parasites such as roundworms during the spring and summer, with external parasites like lice surfacing during the winter months. However, southern areas are often at greater risk of larger parasite populations, and are where internal parasites may be found in pastures for eight to nine months out of the year.


2. Weather

The weather will continually influence parasite populations, as it directly impacts pasture growth. In drier conditions, it’s more difficult for larvae to move up and down on the grass blade. This means that parasites are less likely to be ingested by cattle, because they stay near the ground or may be stuck in a dry fecal pad.


Consistent rainfall encourages faster-growing pastures, and allows for continuous re-exposure to larvae throughout the grazing season. “From year to year, the quality of grass and moisture levels changes,” stated Dr. Gillespie. “Green pastures and moisture both provide an excellent opportunity for cattle to be exposed to parasite larvae in the grass.”


Producers are encouraged to consider the amount of precipitation received each year and adapt deworming protocols with their veterinarian accordingly.


3. Type of Operation

“Although cow-calf and yearling operations have the highest risk levels for parasite populations, all beef herds can benefit from a strategic deworming program,” said Dr. Gillespie. “Using quality deworming products will pay off for producers, because it decreases inefficiencies caused by internal parasites, and increases the likelihood of cattle reaching their profit potential.” 


In a recent study on a cow-calf operation over a two-year period, there was a 12% improvement in reproductive performance for cows that were free of roundworms. In addition, calves of treated cows had an average weaning weight of over 40 pounds more than the non-treated group.2


“Deworming is an absolute requirement, as things can really go wrong when there’s a heavy worm load,” asserted Jim Seaton, DVM, Seaton Vet Clinic, Denison, Iowa. “When clients deworm properly, they save money in the long run.”


An effective deworming program will start by eliminating the adult worms in the system, rendering them unable to shed eggs into the environment and establish a cycle of pasture reinfestation.


“If we’re deworming early on and can keep animals on pasture longer, we’re going to see a bigger return on our investment, and calves will do better in the feedlot,” added Dr. Seaton.


Dr. Gillespie recommends administering a long-lasting injectable dewormer in the spring or early summer, and following up with a quality topical dewormer as cattle come off pasture in the fall.


“Every beef herd is unique, and the timing of product administration will significantly impact the success of a deworming program,” concluded Dr. Gillespie. “Remember to work with a veterinarian to establish a cost-effective deworming program for your herd.” 


Source: Boehringer Ingelheim