Nematode egg counts during the first postpartum month is a useful tool for milk production prediction in grazing Holstein cows

MEJIA, ME; PERRI, AF; LICOFF, N; MIGLIERINA, M; BECU-VILLALOBOS, D; ORNSTEIN, A; ISABEL MARIA LACAU

Buenos Aires

Congreso; 23rd World Association for the Advancement of Veterinary Parasitology Congress; 2011

WAAVP y AAPAVET

The onset of anthelmintic drugs resistance in cattle makes essential to design alternative control strategies with integrated approaches including parasite burden and production parameters. It is critical to identify target animals to be treated, and times of treatment, avoiding massive drug use. To this respect a study comparing three nematode infection diagnostic methods for milk production prediction in dairy cows was performed. Grazing cows from the Experimental School of Inchausti, 25 de Mayo, Buenos Aires, Argentina (35°36’ S, 60°32’ W) that calved in a year (N=150) were individually sampled for rectal feces, coccigeal blood and milk during their first month after calving. Nematode eggs (EPG) were counted in feces by the Mc Master method adapted by INTA. Pepsinogen (P) was measured in serum by the colorimetric method of Ross et al. and expressed as Tyrosine mU/ml. Anti Ostertagia antibodies concentration was evaluated in milk by the Svanova ELISA kit and Optical density ratio (ODR) calculated according to manufacturer instructions. Individual daily milk production was recorded by means of the Alpro-Milking computarized system and lactation curves were performed for each cow. Cut-off levels were established for each measured nematode parameter to separate cows in two groups (with high or low parasite indexes) for each method. Monthly milk yield was compared between groups by two way ANOVA for repeated sampling and total milk production was compared by t-Test for each diagnostic method. Only when cows were separated by the EPG method (EPG = = 0 vs EPG > 0) a difference in total milk production was found (P < 0.05), and productivity differed during the first five month of lactation (P < 0.05).  Milk production from groups of cows separated by Anti-Ostertagia levels in milk expressed as ODR (ODR <= 0.5 vs ODR > 0.5), or by serum pepsinogen expressed as Tyrosine units (Tyr < = 1000 vs Tyr > 1000) did not differed. We conclude that EPG counting during early lactation in grazing dairy Holstein cows may be a useful tool to identify the animals susceptible to have impaired production due to nematode burden.