[1] Agricultural Acad, Agr Inst, Shumen 9700, Bulgaria
[2] Harper Adams Univ, Anim Sci Res Ctr, Agr & Environm Dept, Newport TF10 8NB, Shrops, Wales
[3] Trakia Univ, Med Fac, Social Med Hlth Management & Disaster Med, 11 Armeiska Str, Stara Zagora 6000, Bulgaria
[4] Trakia Univ, Med Fac, Dept Med Chem & Biochem, 11 Armeiska Str, Stara Zagora 6000, Bulgaria