The periparturient egg rise (Shepherd’s Notebook)
(Editor’s note: Susan Schoenian is a sheep and goat specialist with the University of Maryland.)
The periparturient egg rise (PPER) is a natural phenomenon whereby the ewe/doe suffers a temporary loss of immunity (to parasites) around the time of lambing/kidding.
The result is an elevated fecal egg count, which serves as the primary source of infection for susceptible lambs/kids.
The impact is amplified if lambing/kidding coincides with hypobiotic (arrested) worms resuming their life cycle in the spring.
Though it varies by breed and other factors, the PPER can start as early as two weeks before parturition and last up until 8 weeks after.
Thirty days post-partum is typically the peak.
All sheep and goat producers need to have a strategy for managing the PPER.
Traditionally, it was recommended that all ewes/does be dewormed prior to (or around the time) of parturition.
This strategy worked well until the worms started developing resistance to the drugs.
As a result, it is now recommended that only animals that require treatment or would benefit most from treatment be dewormed.
This is called “targeted selective treatment.”
TST works so long as those animals needing treatment are accurately identified.
There are various criteria that can be used to make such determinations.
FAMACHA is commonly used to identify sheep/goats that need deworming.
In the case of the periparturient female, only ewes/does with FAMACHA scores of 4 or 5 usually need dewormed.
Sheep/goats with poor body condition are more susceptible to worm infection.
Periparturient ewes/does with body condition scores of 2 or less need dewormed.
Higher producing animals are usually more susceptible to worm infection.
High producing dairy goats (or sheep) or those freshening for the first time should be dewormed.
Ewes/does carrying or nursing three or more offspring should be dewormed.
First-time mothers, especially yearlings and/or those nursing twins or more will benefit from treatment.
When deworming, it is important to give an effective treatment.
Sometimes, a combination treatment (more than one drug at the same time) is needed.
In fact, combination treatments are now recommended for clinically-parasitized animals.
There are other strategies besides deworming that can be used to manage the PPER.
Increasing the protein content (above NRC requirements) of late gestation rations may negate the effects of the PPER.
By-pass protein is especially beneficial.
If ewes/does are kept in confinement or dry lot during the periparturient period, the effect of the PPER is minimal.
Lambing/kidding certain times of the year (winter, fall) will lessen the impact.
If lambing/kidding occurs on pasture or in the spring, the new product BioWorma can be fed to ewes/does to reduce contamination of pasture caused by elevated fecal egg counts.
Some breeds of sheep and goat are simply more resistant to internal parasites, including the periparturient egg rise.
In sheep, breeds of Caribbean origin or native to the southeastern United States are most resistant.
In goats, Myotonic, Kiko, and Spanish goats may be more resistant to worms than Boers.
If raising one of these breeds or crosses isn’t an option, selection within any breed can be successful. Parasite resistance is a moderately heritable trait, though periparturient FEC may be somewhat less heritable.
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