Have You Checked Your Deworming Protocols?

Published on Thu, 10/15/2020 - 10:45am

 Have You Checked Your Deworming Protocols?

 By Jaclyn Krymowski.

 Internal parasites are an unseen, silent enemy present on every dairy around the globe. They are a fact of life for every animal exposed to the outdoor elements, but thanks to our human interactions and domestication we’ve been able to create environments that greatly mitigate them. But don’t get too comfortable in thinking you’re always as on top of this game as you may think.

Parasites tend to be more correlated with pasture-centric settings such as beef cattle or organic dairies. But they are still present in confinement facilities as well. Parasitic loads, even in subclinical numbers, still pack a powerful punch in production by reducing milk output and efficiency. Treatment and prevention are simple and effective, but these protocols must be part of the management strategy.

It starts with testing
It doesn’t matter what animal you’re deworming; the experts always preach the importance of sampling and testing. Even if you and your vet have worked out a seasonal deworming strategy, there is benefit checking for residual eggs and parasitic load even after anthelmintic treatment. This should be the go-to first step in your annual or seasonal deworming protocol.

In The Fecal Examination: A Link in Food Animal Practice, an article in The Compendium – Food Animal Parasitology, Drs. Donald H. Bliss and William G. Kvasnicka cite the Modified Wisconsin Sugar Flotation Method as being the sole on-farm fecal exam sufficient for identifying parasitic eggs in dairy cattle. Other fecal exam techniques used in small animals and even sheep are unreliable for bovines. The benefit of this is float is not only can it be used in the traditional sense, to identify worm load and the types, it can also detect small amounts of eggs that may remain even after the initial deworming. Another benefit of this float is that it can be done anywhere, requiring very few inexpensive tools and only two main ingredients – hot water and sugar.
Once the float has been conducted, you can examine with a microscope. Some operations train employees to do this on-site, saving on vet bills.

On-farm testing not only gives you a pulse on the parasitic load of the herd at any given time, but also of individuals. Certain animals will always be more susceptible than others, meaning they will always carry a larger wormload and shedding to their herdmates. These may require more frequent deworming treatment, or in extreme cases culling all together.

Follow a routine
How you craft a schedule to go with your protocols will be reflective of your management style. Those in a traditional confinement set up will have a schedule than one that is extensively pasture based.

The transition period is tied up with a multitude of things on the dairy’s “to-do list” for each individual animal. In the midst of changing up the diet, giving any pre-fresh shots, hoof trimmings and other things, deworming should also be somewhere on the list. Or, preferably, doing a fecal test to see what your deworming needs are.

If you are using a dairy-friendly dewormer with no withdrawal period, you could easily opt to treat either late in lactation just before the dry-off period all the way through the pre-fresh period. Whatever you do, keep it consistent so you can go through and treat by group at a certain stage in the lactation or transition and no one gets overlooked.

Heifers don’t really need to worry about parasitic issues until weaning. However, prevention should still start early with something as simple as a starter grain treated with a coccidiostat. But as heifers move into weaned life and are exploring more, interacting with herdmates and eating hay, grass and/or silage, they are introduced to a whole host of parasites.

In a confinement setting, a single treatment in the weaned pen could very well suffice through first calving. On pasture, the exposure to worms is significantly more prominent.

Wormload on a particular pasture can vary significantly depending on rainfall, humidity and season among other things. It is usually recommended to deworm at initial turnout, sometime later, and again when you take them off pasture. But a routine alone isn’t enough, you must incorporate knowledge of your pasture, grass management, visual inspection and fecal testing when necessary.

Pasture rotation can be used to prevent grass from getting too short where animals will be forced to graze low, closest to more larvae and eggs. It will also keep them grazing too close to fresh manure, a ground zero for larvae and eggs. You should also avoid putting young heifers on pasture recently occupied by mature cows who will just have shed a fresh batch of eggs for infestation.

Something of interest to organic and other pasture-based dairies are grazing forages with anthelmintic properties. Dr. Ann Wells, in her white paper Integrated Parasite Management for Organic Dairy Cattle, noted “herbal leys” or pastures up made of specific forages known to discourage and reduce parasites is an idea developed mostly for sheep and goat producers, but it can work for large ruminants as well. Certain plants, she noted, with either condensed tannins or sesquiterpenes have shown a negative effect on internal parasite populations, as seen in plants such as chicory. More research in this area is needed, but strategic seeding of some plants such as chicory may become part of a farm’s whole worming program.

Don’t get too familiar
If your veterinarian is familiar with the parasitic issues you tend to face, he or she can likely prescribe a go-to dewormer. However, some caution is needed when it comes to utilizing a “regular” dewormer for your cattle. While not quite as pressing of an issue as in certain species (such as goats), resistance to anthelmintic is not unheard of in cattle.

Your veterinarian should be involved in deciding on a dewormer, especially one you intend to use for an extended period of time. Wormers no longer working should be discontinued immediately and replaced with another product. Testing may reveal some individuals can go without any deworming treatment for some period of time.

On well-managed dairies, parasites are seldom a serious concern. But to maintain that status, the best managers are aware of the microscopic activity happening on a herd-wide scale. Stay vigilant, work with your entire animal health team and your deworming protocol is sure to get results.