Faculty of Veterinary Medicine University of Zagreb
Abstract
This study investigated the effect of an antiparasitic ivermectin (IVM) drug on the endocrine reproductive hormones of twenty healthy adult 250-350 kg Baladi cows that were 4-7 years of age. The cows were divided into two groups (n = 10 each). The first was a control group injected with physiological saline; the second group was treated with the recommended therapeutic dose of IVM (0.2 mg/kg, s/c) one day after parturition. Blood samples were taken on the 1st, 15th, 30th and 90th day after IVM treatment. The results revealed that IVM injection at one day after parturition delayed estrous for up to 3 months (absence of estrous signs and rectal palpation revealed no ovarian structures). IVM significantly (P<0.05) decreased serum follicular stimulating hormone (FSH), luteinizing hormone (LH) and estradiol for up to 3 months. In addition, IVM significantly (P<0.05) increased serum progesterone, prolactin and cortisol for up to 3 months. Further, IVM caused unobservable changes in serum testosterone and sex hormones binding globulin. Serum calcium levels significantly increased on the 1st day of IVM injection, while serum phosphorus significantly decreased on the15th and 30th day of IVM injection. It was concluded that IVM delayed estrous in cows for three months via disturbances in the female reproductive hormones and calcium/phosphorus homeostasis. Therefore, it is recommended that IVM should not be injected directly after parturition. Furthermore, the increased calcium after IVM indicates that an overdose of IVM should not be counteracted by calcium therapy; instead, any other antiallergic preparation could be used.Kod 20 zdravih i odraslih krava baladi pasmine, čija se tjelesna masa kretala od 250 do 350 kg, a dob od 4 do 7 godina, istražen je učinak antiparazitika ivermektina (IVM) na spolne hormone. Krave su bile podijeljene u dvije skupine (10 u svakoj skupini). Prvoj, kontrolnoj skupini bila je prvog dana nakon teljenja ubrizgana fiziološka otopina soli natrijeva klorida, a drugoj preporučena terapijska doza ivermektina (0,2 mg/kg, s/c). Uzorci krvi bili su prikupljeni 1., 15., 30. i 90. dana nakon primjene ivermektina. Rezultati su pokazali da je njegova primjena dan nakon teljenja dovela do odgode estrusa u trajanju do 3 mjeseca (izostali znakovi estrusa i strukture pri rektalnoj palpaciji jajnika). U razdoblju od 3 mjeseca došlo je do signifikantnog (P<0,05) sniženja razine folikulostimulirajućeg hormona (FSH), luteinizirajućeg hormona (LH) i estradiola u serumu. U istom razdoblju ivermektin je uzrokovao signifikantan (P<0,05) porast serumskog progesterona, prolaktina i kortizola, te slabo uočljive promjene razine serumskog testosterona i globulina koji veže spolne hormone. Razina kalcija u serumu značajno je porasla 1. dana, dok je razina fosfora u serumu signifikantno pala 15. i 30. dana od primjene ivermektina. Zaključeno je da ivermektin odgađa estrus kod krava u trajanju od 3 mjeseca putem narušavanja ravnoteže spolnih hormona odnosno poremećaja homeostaze kalcija i fosfora. Zbog toga se ne preporučuje njegovo davanje netom nakon teljenja. Nadalje, povišena razina kalcija nakon njegove prekomjerne primjene ne bi se smjela suzbijati davanjem kalcija, već upotrebom drugih antialergijskih pripravaka
