Comparison of three methods for gastrointestinal nematode diagnosis determination in grazing dairy cattle in relation to milk production

摘要: Abstract Development of resistance to anthelmintic drugs has motivated the search for diagnostic methods identify animals targeted selective treatments. We compared three diagnosis nematode infection in relation milk production a fully grazing dairy herd 150 cows humid Pampa (Argentina). Animals had feces, blood and sampled during first postpartum month EPG, pepsinogen anti- Ostertagia antibody determination, respectively. With results obtained two groups cows, divided high low parasite burden, were conformed each method, was then between groups. When separated by EPG method (EPG = 0 ( N  = 106) vs. EPG > 0  = 44)) difference nearly 800 l per cow lactation found P  1000) or (ODR ≤ 0.5 ODR > 0.5) did not differ. Interestingly, proportion group differed yielded significantly more index using Pepsinogen method. No correlations indexes determined different methods. High burden estimation may be ascribed system, all year round, sampling time, at beginning with negative energy balance depressed immunity. The fact that born reared outside, on pasture continuous larvae exposure, also account obtained. In conclusion, counting useful tool impairment induced adult cows. treatment only EPG-positive recently calved would improve production, while reducing pressure population development resistance.