Have you ever considered why your sheep have intestinal parasites present at the end of the winter period? Hypobiosis or inhibition is one possibility. This occurs when the parasites that have been ingested during the autumn entered a stage of arrested development. Thus, causing the parasite to stop development until the environmental conditions become more favourable. For more information on Hypobiosis, please visit our previous article ‘Hypobiosis – The Dormant Nematode’.
Mass emergence of parasites and the subsequent periparturient egg rise is seen with many parasites following the development of hypobiotic larvae over the winter period.
As mass emergence of parasites occurs when environmental conditions become more favourable it is normally seen during the spring. For this reason, it is sometimes called the spring rise and is an event that all sheep farmers should remain mindful of, especially during spring lambing.
Mass emergence results in high numbers of parasites. This subsequently results in a greater volume of parasitic eggs. These eggs can be found on grazing pastures and are largely responsible for the infections acquired by lambs during grazing, as they contaminate pasture for naïve lambs, initiating the cycle of infection. The infected lambs can then cause a further increase in pasture contamination, potentially leading to very high levels of pasture infectivity during late summer and autumn.
Mass emergence of parasites and the periparturient egg rise is a particular risk for sheep that are lambed on pasture for the above reason. The risks and effects of the periparturient egg rise is minimal to indoor raised lambs as the eggs are not deposited on to pastures, meaning sheep are not continuously ingesting new larvae.
How can you help to prevent periparturient egg rise?
Conducting a pastural larval count will identify any parasitic contamination of your pasture. Here at Ridgeway, we offer pasture larvae counts to help you determine the status of your pastures, therefore, allowing you to manage and minimise the risk to your flock in the lambing season. You can also identify parasite burdens within your flock with regular faecal egg counts. Please visit our website where you can find more details on the services we offer and how you can request a pasture larvae count or a faecal egg count: https://ridgewayresearch.co.uk/services/
References:
Cornell University (2023) Periparturient Egg Rise in Sheep and Goats. Available at: https://www.ccedelaware.org/2020/04/16/periparturient-egg-rise-in-sheep-and-goats/#:~:text=The%20phrase%20%E2%80%98periparturient%20egg%20rise%E2%80%99%20refers%20to%20the,and%20up%20to%208%20weeks%20after%20giving%20birth (Accessed: February 2023).
Dinesh Kumar, S., et al. (2022) ‘Dynamics of Gastrointestinal Parasitism in Sheep during Peri-parturient Period on Organized Farm’, Journal of Animal Research, 12(1), pp.39-45. DOI: 10.30954/2277-940X.01.2022.6
Hamer, K., et al. (2019) ‘The dynamics of ovine gastrointestinal nematode infections within ewe and lamb cohorts on three Scottish sheep farms’, Preventive Veterinary Medicine, 171, pp.1-10. DOI: https://doi.org/10.1016/j.prevetmed.2019.104752
Schoenian, S. (2012) ‘The periparturient egg rise’, American Consortium for Small Ruminant Parasite Control, December 2012. Available at: https://www.wormx.info/pper (Accessed: February 2023).