First report on anticoccidial drug resistance in Eimeria species of broilers from Kashmir, a North-Western Himalayan region.

Abstract

This study represents the first report on anticoccidial drug resistance in Eimeria species infecting broiler chickens in Kashmir, North India, a region with unique temperate climatic conditions conducive to oocyst survival. A mixed population of field strains of Eimeria spp. from poultry farms in Kashmir Valley was evaluated to assess the current anticoccidial resistance status following World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines. The oocyst inoculum comprised of seven Eimeria species identified morphologically, of which five (E. acervulina, E. maxima, E. mitis, E. praecox and E. tenella) were confirmed molecularly using the ITS-1 rDNA marker. Forty, One-day-old Cobb-strain broilers, were randomly divided into four groups (n = 10 each): Group I (infected + amprolium treated), Group II (infected + sulphaquinoxaline treated), Group III (infected untreated control) and Group IV (uninfected control). Drug efficacy was determined by calculating the percentage global index (%GI) based on weight gain, feed conversion ratio, lesion score, oocyst index and mortality. The %GI values were 58.15 for sulphaquinoxaline-treated group and 56.86 for amprolium-treated group, indicating partial resistance, defined here as a moderate loss of drug efficacy without complete treatment failure. Morpho-Molecular analysis identified five Eimeria species in pre-treatment samples and detected the continued presence of four Eimeria species post-treatment, indicating potential emerging drug resistance. Phylogenetic analysis of ITS-1 sequences showed a close genetic affinity of local isolates with reference Eimeria strains deposited in GenBank and notably, this is the first report of ITS-1 sequences for E. praecox from Kashmir. In conclusion, the study provides the first molecularly supported evidence of anticoccidial resistance in broilers from Kashmir and underscores the need for routine monitoring, rotational use of anticoccidials and the adoption of integrated parasite control strategies to safeguard poultry productivity in the region.