The effect of Brachiaria brizantha cultivars on host-parasite-environment interactions in sheep naturally infected with gastrointestinal nematodes

Abstract

The objective was to evaluate the effect of different cultivars of Brachiaria brizantha on the dynamics and concentration of the larval stages of gastrointestinal nematodes in the soil and forage strata, as well as their effects on the performance of naturally infected lambs. Overall, 48 90-day-old lambs with an initial weight of 19.04 ± 0.96 kg were observed. Moreover, a randomised block factorial design with four cultivars of Brachiaria brizantha (Marandu, Xaraé s, Piatã and Paiaguá s grasses) under intermittent stocking (with a pre-grazing canopy height of 40 cm and post-grazing canopy height of 20 cm) for two grazing cycles was used. The following variables were analysed: faecal egg counting, faecal culture, mean corpuscular volume, FAMACHA © score, weight and body condition score, the recovery of larvae from pasture and soil samples, nutritional value and the production and structural components of forage. Lambs grazing Marandu grass demonstrated the highest level of nematode infection (P < 0.05). However, the nutritional value did not differ between cultivars. Marandu grass had the highest pasture density (P < 0.05), while Paiaguá s grass had the highest percentage of dead material (P < 0.05). The various genera of gastrointestinal nematodes found in the faecal cultures, regardless of the cultivars, include Haemonchus (92.01%), Trichostrongylus (4.55%), Strongyloides (3.06%) and Oesophagostomum (0.37%). Lambs grazing Xaraé s grass had the lowest body weight (P < 0.05). Furthermore, larvae concentrations were highest in Marandu and Paiaguá s pastures; infective Haemonchus and Trichostrongylus larvae were recovered from pasture and soil samples. The different cultivars of Brachiaria brizantha produce diverse and relevant microclimatic conditions to contaminate soil, pastures and animals. Animal performance was not compromised despite the Marandu and Paiaguá s cultivars having the highest levels of contamination and infection. Based on parasitological aspects, the Brachiaria brizantha cultivars Xaraé s and

Extruded urea levels in lamb supplementation in rainy tropical savanna conditions: the triad host-gastrointestinal nematodes-environment

“…Among the genera observed in coprocultures, Haemonchus and Trichostrongylus were the most frequent, corroborating several studies (Roberto et al, 2020;Gurgel et al, 2020;Roberto et al, 2018;Hoste et al, 2016). These two genera are the main gastrointestinal parasites of sheep, a cosmopolitan habit, due to the biological peculiarities of each one (including feeding method and reproduction rate); its epidemiological characteristics; their pathophysiological effects and the development of anthelmintic resistance (Hoste et al, 2016), which makes them a global concern for veterinary parasitology and ruminant production in pasture.…”

“…For the recovery of the larvae of the NGIs in the pastures, ve random samples were collected per paddock, in the early morning, with the aid of a square of 0.50 m 2 and cut close to the ground. The samples were placed in plastic bags, identi ed and processed according to the modi ed method by Quadros et al, (2012) and described by Roberto et al, (2020), in order to recover the larvae from the pasture. All larvae present in the nal sample content were counted and classi ed into larval stages L1/L2 and infective larvae (L3) and these were identi ed according to genera by their morphological characteristics (Keith, 1953).…”

“…Soil collections were carried out simultaneously with pasture collections, with the same number of samples and below the clumps collected in the paddocks, at a depth of 0-5 cm, with the aid of a gardening shovel. The recovery of larvae from the soil was carried out using the methodology described by Roberto et al, (2020). The quanti cation and identi cation of larvae were performed according to the methodology described by Keith (1953).…”

“…However, the microclimate formed by forages is of great importance for the development and survival of the different larval forms, as well as the eggs of the NGIs. The feces, soil and plant components behave as a reservoir and main means for the ingestion of infective larvae (Roberto et al, 2020).…”