Q.
What is the periparturient egg rise?
A.
The periparturient egg rise (PPER) is a natural phenomenon whereby ewes/does suffer a temporary reduction in immunity to gastro-intestinal parasites around the time of lambing/kidding. The result is an increase in fecal egg counts which serves as the primary source of infection for grazing offspring. The reason for the pariparturient egg rise is not completely understood, but it is believed to be the result of both hormonal and nutritional factors. It occurs from two weeks before parturition up to 8 weeks after. Thirty days post-partum seems to be most common.
All sheep/goat producers should have a strategy for dealing with the periparturient egg rise. Traditionally, it was recommended that ewes/does be dewormed in the last month of pregancy. For convenience, many producers dewormed ewes/does right after birthing, while they were in the jugs. Due to the widespread development of drug resistant worms, it is now recommended that not all ewes/does be dewormed, but instead the principles of targeted selective treatment be applied. Target selective treatment is when you only deworm those that require treatment or would benefit from treatment. Leaving some females untreated preserves refugia (drug-susceptible worms).
Deworming is still an effective strategy for the periparturient period, but using the principles of targeted selective treatment, only ewes/does meeting certain critera would be dewormed prior to or at the time of parturition. Ewes/does with FAMACHA© scores of 4 or greater should be dewormed. Ewes/does with body condition scores of 2 or less should be dewormed. Ewes/does with 3 or more offspring should be dewormed. Yearlings and first time moms/fresheners should be dewormed. High producing dairy goats should be dewormed. Females that don't meet one or more of these criteria should be left untreated.
Levamisole (Prohibit®, Leva-Med®) should probably not be given to pregnant does, as there are claims of abortion. The albendazole (Valbazen®) label warns against its use in the first 45 days of pregnancy. When ewe/does are dewormed prior to parturition, they should be gently handled and not handled too close to their due dates.
Lambing/kidding at certain times of the year will lessen the magnitude of the periparturient egg rise. In most climates, this would be winter or fall. Ewes/does birthing in the spring are impacted most by the periparturient egg rise, since this is also when hypobiotic worms are resuming their life cycles.
Another way to reduce the impact of the periparturient egg rise is to increase the level of protein in the late gestation diet. Research has shown this to reduce fecal egg counts in pregnant ewes. By-pass protein seems to be especially beneficial. By-pass protein is protein that "escapes" the rumen and is digested further down the digestive tract. All feedstuffs have some by-pass protein. You can check nutrient composition tables to see which feedstuffs have higher percentages of by-pass protein.
Feeding forages with condensed tannins (e.g., sericea lespedeza) has been shown to reduce the periparturient egg rise in ewes/does. Sericea lespedeza is a warm season legume that grows in lesser quality soils. Unfortunately, sericea lespedeza is considered invasive in some states.
BioWorma® can be fed to ewe/does during the periparturient period to reduce the infection of pastures. BioWorma® is a nutritional supplement that contains a worm-killing fungus (Duddingtonia flagrans). While having no effect in the animal, the fungus traps and kills roundworm larvae in the manure, greatly reducing infection of pastures with worm larvae. Clinically parasitized animals would still require deworming
Keeping periparturient ewes/does in confinement (zero grazing) is an effective strategy for managing the periparturient egg rise. This is common with ewe/does that birth during the winter months, but can be done any time of the year. Parasites do not survive well in bedding or on slats. Sheep/goats don't generally get infected with worm parasites in confinement. The opposite is true for coccidia, and similar to worm parasites, ewe/does will have higher oocyst counts during the periparturient period. They are the source of infection for their offspring. This is why many producers feed a coccidiostat to ewes/does during late gestation. Feed a coccidiostat to pregnant females requires extra label drug use.
Selection is a longer term strategy for reducing the impact of the periparturient egg rise. Collecting fecal egg count data on periparturient females has been proposed as an alternative to collecting samples from growing animals. Adults (especially sheep) are better able to cope with the negative effects of parasitism. The heritability of periparturient fecal egg count (in ewes) is considered to be low to moderate. The magnitude of the periparturient egg rise is less in more resistant breeds.
5/28/21
Additional resources
Periparturient egg rise -Best Management Practices (wormx.info)
Periparturient Egg Rise Video | PowerPoint slides