Internal parasites are often the #1 health issue producers face with ruminant herds such as cattle, sheep, and goats. It can cause economic loss in many segments of production. Infestations of internal parasites can cause low weight gain, reduced pregnancy rates, reduced weaning weights, reduced milk production, diarrhea, anemia, dull coats, immune suppression, and in severe cases death.
Dewormers are often used by producers to reduce parasite loads, the effectiveness of dewormers has been reduced over time due to increased resistance in the parasite populations. One tool that can be added to your toolbox to help fight internal parasites is implementing better grazing practices.
To know how to break the parasite cycle, first, you need to know how the cycle works. Animals consume food in this case grass containing the infective stage (typically L3 larvae) of the parasite. The larvae will then develop into adults which live in the abomasum and intestines of ruminants and begin producing eggs. The animal will shed eggs of the parasite in their manure. Those eggs will then hatch and the larvae will develop in the grazing system continuing the cycle.
Rotational Grazing – Rotational grazing is defined as “a grazing method that utilizes repeating periods of grazing and rest among two or more paddocks or pastures.” When our livestock are forced to graze the same pasture continuously, they will repeatedly return to desirable areas. These desirable areas typically have a heavier manure load and a lower grazing/stubble height. This leads to re-infecting themselves with more parasites. Frequent and severe grazing pressure also weakens forage plants leading to lower forage yield and increased weeds. Rotational grazing allows producers to control how short plants are grazed (stubble height), the length of time animals graze in a paddock, and the length of time in between grazing events.
Under ideal temperature and moisture conditions (warm and wet), parasites can go from egg to L3 in 3 to 4 days. Using a grazing rotation to stay ahead of this cycle is preferred. The key is to subdivide fields so that the animals have enough to eat for 4 to 5 days. Fields can be subdivided using temporary fencing or permanent fencing. These smaller areas allow animals to graze the forages that are present in the field more evenly. Rotate animals into a new field within five days to stay ahead of the parasite life cycle.
Photo – Dan Glenn (Deep Grass Graziers)
Photo – Dan Glenn (Deep Grass Graziers)
Grazing Heights – Leaving 2”-4” of plant/stubble height is recommended. When possible, leaving 4”-6” of stubble height is even better. By not allowing your animals to graze below this 2”-4” mark it will reduce the risk of animals ingesting larvae. Once larvae hatch, they travel up the blades of grass to increase the chance of being ingested. If you are unsure of how to adequately estimate grazing height, a grazing stick can be utilized. Contact your local county extension agent for a grazing stick.
Photo – H. Anderson
Multispecies Grazing– Sheep and Goats share a lot of the same internal parasites. Cattle and horses do not generally share the same gastrointestinal parasites as sheep and goats. This is where grazing them all in the same area can be beneficial. You can choose to graze them all together or have one species lead or follow another on the grazing area. Multispecies grazing can also lead to increased weed control in pastures since desired forage types can be different among cattle, sheep, and goats.
Photo – H. Anderson
Avoid Overstocking – Stocking rates are heavily based on grazing quality. A better-quality faster-growing forage can handle a higher stocking rate than a low-quality forage. When looking at different ruminant species and using cattle for comparison, you can graze 6-8 goats, or 5-6 sheep, per Cow. So, if your pasture stocking rate is one 1,000 lbs. cow per two acres you could sustain grazing 5-6 sheep on the same 2 acres of pasture. Calculating stocking rate can be found at this link here UGA Forage Team Is your stocking rate correct?
Managing your grazing is not going to be a fix-all for parasite control issues in livestock however, it can be a very effective tool in your overall system. Other tools such as chemical control and genetic selection should never be forgotten for managing parasites in your herd.