Evaluation of parasite resistance to commonly used commercial anthelmintics in meat goats on humid subtropical pasture

Anthelmintic-resistant gastrointestinal nematode parasites are a threat to small ruminant industry sustainability. Meat goat does were administered one of four anthelmintics orally (ivermectin (n = 18), moxidectin (n = 18), levamisole hydrochloride (n = 17), or albendazole (n = 19)) or water (n = 18). Fecal samples were collected pretreatment and 12 days post-treatment. Fecal egg counts (FEC) were determined by the modified McMaster technique. The FEC reduction percentages (FECR%) were calculated using three equations. Log transformed FEC means were analyzed by treatment, sire breed of doe, and doe age. Sire breed affected (P \u3c 0.05) pretreatment FEC, but not post-treatment FEC (P = 0.12). Pretreatment FEC did not differ (P = 0.21) by treatment group. Posttreatment FEC varied (P \u3c 0.05) by treatment. Anthelmintic resistance determinations were based on FECR% falling below 90% or 80%, dependent on equation applied. Resistance was detected to all four anthelmintics using each equation. These results suggest the need for alternative methods of internal parasite control in goats