159 The effect of multispecies swards on parasite faecal egg counts of grazing lambs

Abstract

Abstract Multispecies swards (MSS) for ruminants are increasing in popularity in temperate regions. The objective of this study was to evaluate the effect of MSS containing grasses, legumes and herbs on lambs faecal egg counts (FEC) compared to a perennial ryegrass monoculture. Over two years (2015 and 2016) lambs (n = 60 per year, n = 120 in total per treatment) grazed one of four sward types. The treatments were: perennial ryegrass only (PRG), perennial grass and white clover (PRGWC), six species sward (perennial ryegrass, timothy, plantain, chicory, white and red clover; 6S) and nine species (9S) additional to the 6S were cocksfoot, greater birdsfoot trefoil and yarrow. Feces samples were collected fortnightly commencing when lambs were six weeks old and FEC were determined by the modified McMaster procedure for quantifying Nematodirus and Trichostrongylus eggs. All lambs were treated with anthelmintic at 12 weeks of age and subsequent anthelmintic treatments were administered when a threshold of 400 egg per gram (epg) was reached. The statistical analysis used was a repeated measures model in PROC MIXED of SAS. Nematodirus FEC did not differ with treatment (P > 0.05). Trichostrongylus FEC was influenced by sward type (P < 0.05), the lambs grazing the PRG sward displaying higher FEC, while the lambs grazing the 9S sward displaying lower FEC compared to other treatments. The lambs offered PRG required fewer days in reach the 400 epg threshold compared to the other treatments (P < 0.05) that did not differ. The repeatability of FEC from one date to the next date was 21.54% and 11.85% for Nematodirus and Trichostrongylus respectively, being considered low. The correlation between FEC (Nematodirus) and ADG (weaning-slaughter) was positive (0.1377), but FEC (Trichostrongylus) and ADG correlation was negative (-0.1084). These results suggest that lambs offered the 9S treatment had lower FEC of Trichostrongylus eggs compared to PRG.