Interferences on microbial inhibitor tests related to ivermectin treatment in lactating dairy goats.
This Research Communication reports interferences related to the administration of ivermectin in lactating dairy goats on the response of microbial tests for screening antibiotics in milk. Twenty-eight Murciano-Granadina goats, naturally infested with Sarcoptes scabiei var. caprae, were treated with a subcutaneous injection of ivermectin (200 µg/kg b.w.). To prevent re-infestation, a second dose was applied 7 d later. Individual milk samples were collected, daily, up to 15 d post-treatment. Milk samples were analysed by microbial inhibitor tests (BRT MRL, Delvotest SP-NT MCS and Eclipse 100) and ivermectin residues were quantified by HPLC. A large number of positive results were obtained for all microbial tests, especially on the first day after treatment (BRT MRL = 46·4%; Delvotest SP-NT MCS = 14·3%; and Eclipse 100 = 17·8%). However, the highest concentration of drug residues in milk (24·3 ng/ml) was detected on the tenth day after treatment, when positive outcomes were relatively lower (BRT MRL = 17·8%; Delvotest SP-NT MCS = 10·7%; and Eclipse 100 = 7·4%). Results herein suggest that factors related to the ivermectin treatment other than drug residues in milk, or alterations produced by the parasitic disease itself affecting the immune response of animals, could be the cause of false-positive results in microbial tests. It can be concluded that the application of ivermectin in dairy goats infested with sarcoptes mange during lactation produces persistent drug residues in milk, and could also cause false-positive results in microbial inhibitor tests for screening antibiotics.
Instituto de Ciencia y Tecnología Animal,Universitat Politècnica de València,Camino de Vera,s/n. 46022. Valencia,Spain.
Tamara
T
Romero
Instituto de Ciencia y Tecnología Animal,Universitat Politècnica de València,Camino de Vera,s/n. 46022. Valencia,Spain.
Vicente Javier
VJ
Moya
Instituto de Ciencia y Tecnología Animal,Universitat Politècnica de València,Camino de Vera,s/n. 46022. Valencia,Spain.
Nemesio
N
Fernández
Cátedra de Biofísica,Facultad de Ciencias Veterinarias,Universidad Nacional del Litoral. R.P.L.,Kreder. 3080. Esperanza,Argentina.
Rafael
R
Althaus
Institute for Agricultural and Fisheries Research,Technology and Food Science Unit (ILVO-T&V),Brusselsesteenweg 370,9090 Melle,Belgium.
Wim
W
Reybroeck
Instituto de Ciencia y Tecnología Animal,Universitat Politècnica de València,Camino de Vera,s/n. 46022. Valencia,Spain.
María Pilar
MP
Molina
D000818:Animals; D004350:Drug Residues / Q000032:analysis; D005189:False Positive Reactions; D005260:Female; D005506:Food Contamination / Q000032:analysis*; D015511:Goat Diseases / Q000188:drug therapy*; D006041:Goats; D007559:Ivermectin / Q000032:analysis* / Q000627:therapeutic use*; D007774:Lactation; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000737:chemistry*; D012532:Scabies / Q000188:drug therapy / Q000662:veterinary
D007559:Ivermectin
Goat milk; ivermectin; microbial inhibitor tests