Effect of growing forage legumes on the migration and survival in the pasture of gastrointestinal nematodes of sheep

Abstract

In order to identify types of forage that inhibit pasture contamination, an evaluation was performed of the effect of the forage legumes Trifolium repens (white clover), Trifolium pratense (red clover) and Lotus corniculatus (bird's-foot-trefoil) on the survival and migration of infective larvae (L3) of gastrointestinal nematodes (GIN) of sheep. An experimental area of 441 m2 was divided into four blocks, subdivided into areas of 1.20 × 1.20 in which the three forage legumes were separately overseeded. After growth of the forage in each subdivision, experimental units were established that were later artificially contaminated with sheep faeces containing GIN eggs. Between October and December 2018, pasture, faecal and soil samples were collected on four occasions during weeks 1, 2, 4 and 8 after the deposition of faeces. In week 6, the forage legumes in all the experimental units were mown to simulate grazing. The number of L3 was quantified to determine their survival in the pasture, faeces and soil. In addition, the horizontal migration of L3 was measured at two distances from the faecal pellets (10 and 30 cm), as well as their vertical migration at two heights of the plant stems, that is, lower half and upper half. Larvae vertical migration was affected by the forage species (P < 0.001), in that bird's-foot-trefoil contained fewer larvae in the upper stratum. Bird's-foot-trefoil restricted the migration of L3 to the upper stratum of the plant, which could potentially decrease the risk of infection by intestinal nematodes in grazing sheep.

Understanding Animal-Plant-Parasite Interactions to Improve the Management of Gastrointestinal Nematodes in Grazing Ruminants

“…The pasture infectivity seems greatly determined by rainfall with high L3 levels in autumn-winter that decreases towards summer [143]. Similar results were obtained in summer in a coastal area in southern Brazil [112,153]. Another rotational system, cited in Sweden, consisted of separate 2 ha-paddocks with a grazing period of approximately 20 weeks [163,164].…”

“…Additionally, the forage and legume species may also influence the ingestion of L3 by animals, which offers a potential tool for reducing contact with the parasite. Garcia-Méndez, et al [153] compared the vertical and horizontal migration of L3 of gastrointestinal nematodes in sheep across three legume species: white clover (Trifolium repens), red clover (T. pratense), and bird's-foot-trefoil (Lotus corniculatus), finding that smaller numbers of L3 were recovered from the upper stratum of the third plant species. Others [154] showed that, depending on the season, the forage species may be either a limiting or facilitating factor of L3 vertical migration.…”

“…Rotational systems with small paddocks minimise the chance of animals coming into contact with fresh faeces, which lowers the risk of contamination, as the time the animals stay in the area is shorter than the time required for the hatched eggs to reach the L3 stage. Allowing adequate rest time for the paddock after grazing and promoting L3 desiccation through exposure to solar radiation can help prevent dung from becoming reservoirs of L3 and reduce paddock contamination [112,137,153].…”

Age‐specific impacts of vegetation functional traits on gastrointestinal nematode parasite burdens in a large herbivore

“…This could be addressed in future using a combination of small‐scale, short‐term studies investigating the effect of plant species on pasture larvae counts in the field and models capable of extrapolating such data to estimate landscape‐level exposure over longer time periods (e.g. Garcia‐Méndez et al, 2022 ; Rose et al, 2015 ). The effect of PC1 is consistent with high‐quality grazing areas being more heavily used by sheep and thus higher strongyle burdens in lambs.…”

Guide to advances in the control of gastrointestinal roundworms in sheep

“…As these plants have a higher protein concentration and often higher levels of trace elements than grass, it may be that some of their effect is nutritional. Also, plant structure may inhibit larval migration, reducing larval ingestion (Garcia‐Mendez and others 2022). These plants may be used in single species stands, to provide high quality, clean grazing for lambs to graze as part of a rotation, or at a particular time of year (eg, after weaning).…”