INVESTIGADORES
FERNANDEZ Alicia Silvina
congresos y reuniones científicas
Título:
Epidemiological study of gastrointestinal nematodes in sheep under organic and conventional production systems in Canada
Autor/es:
MEDEROS, AMÉRICA; FERNÁNDEZ, ALICIA SILVINA; PEREGRINE, ANDREW; KELTON, DAVID; MENZIES, PAULA; VANLEEUWEN, JOHN; LEBOEUF, ANNE; MARTIN, RALPH
Reunión:
Simposio; 12th Symposium of the International Society for Veterinary Epidemiology and Economics (ISVEE); 2009
Resumen:
A Longitudinal study from May 2006 ? March 2007 was conducted on 23 farms in Ontario and 8 farms in Quebec purposively selected (8 certified organic (CO), 16 non-certified organic (NCO) and 7 conventional (C)). On each farm, 10 ewes and 10 female lambs were randomly selected. Monthly visits were undertaken during the grazing season, with two visits in winter. For each visit, fecal samples were taken from individual animals, and pasture samples were obtained from the paddocks during the grazing season. Body condition score (BCS), dag score (DS) and fecal consistency score (FCS) were also recorded for each sheep. Fecal egg counts (FEC) in eggs per gram (EPG) and infective larvae identification (L3) from feces and pasture were performed. Summary statistics were calculated, and using log EPG a multilevel mixed linear regression analysis was fit using SAS 9.1. Other covariates included deworming, temperature, rainfall, and manure application, with random variables for farm effects and repeated sheep measures. Results: The mean FECs were 181 EPG for ewes and 509 for lambs in Ontario, and 351 and 147 for ewes and lambs in Quebec. The month with the highest mean EPG was May for ewes (218) and August for lambs (514) in Ontario, and June for ewes (754) and July for lambs (1187) in Quebec. The mean EPGs for the different types of farming were 94, 287 and 235 for ewes under CO, NCO and C, while for lambs; they were 295, 521 and 417, respectively. From the coprocultures, the nematode species that predominated was Teladorsagia spp (50%), followed by Haemonchus spp (19%). Infective larvae recovered from pasture were highest during June-July (998 L3/KgDM) and September (520 L3/KgDM). In the final model, province, month of sampling, temperature, deworming, age, and BCS (P