The immune responsiveness of Romney sheep selected for resistance or susceptibility to gastrointestinal nematodes: lymphocyte blastogenic activity, eosinophilia and total white blood cell counts

artiodactyla bovidae disease resistance eosinophils ganado genetica genetics granulocitos granulocyte granulocytes immune response livestock nematoda ovin ovinos resistencia a la enfermedad rumiante ruminant ruminants sheep trichostrongylidae trichostrongylus colubriformis