Endokrine i metaboličke promjene u mliječnih krava tijekom peripartalnog razdoblja uzrokovane dodatkom vitamina E i cinka u prehrani

The objective of this study was to measure the effect of vitamin E (Vit-E) and zinc (Zn) supplements on endocrine and metabolic changes in peripartum cows. Thirty-two crossbred (Holstein Friesian×Tharparkar) cows were selected 60 days before the expected date of calving. The cows were arbitrary allocated into 4 groups (n = 8), namely: the control, T1, T2, and T3. The feeding schedule was similar in all the groups except that in T1, T2, and T3 60 mg Zn/kg DM, 1000 IU Vit-E and 60 mg/kg + 1000 IU Zn + Vit-E were additionally added, respectively, from day 60 pre-calving to day 60 post-calving. Blood samples were taken on days 60, 45, 30, 15, and 7 before and after the expected day of calving and on the day of calving. Before calving, the cows showed a decrease in plasma leptin, insulin, glucose, Vit-E, and Zn levels, and an increase in plasma non-esterified fatty acid level. However, increases in plasma leptin, insulin, glucose, Vit-E, and Zn and a decrease of plasma non-esterified fatty acid were observed after calving. After calving, group T3 had higher (P<0.05) plasma leptin, insulin, and glucose concentrations than all the other groups. Plasma Vit-E levels were higher (P<0.05) in groups T2 and T3; however, the Zn level was higher (P<0.05) in groups T1 and T2. Milk yield was observed to be higher (P<0.05) in T3 than in the control and groups T1 and T2. The reduction in leptin, insulin, glucose, Vit-E, and Zn during peripartum was ameliorated by Vit-E and Zn supplementationCilj ovoga istraživanja bio je izmjeriti učinak vitamina E i cinka (Zn) na endokrine i metaboličke promjene u krava tijekom peripartalnog razdoblja. U istraživanje su uključene 32 krave, križanke (Holstein-Friesian × Tharparkar), 60 dana prije očekivanog teljenja. Krave su nasumce podijeljene u četiri skupine (n = 8): kontrolnu skupinu, T1, T2 i T3. Hranidbeni je protokol bio sličan u svim skupinama, osim što je skupinama T1, T2 i T3 dodano 60 mg Zn/kg suhe tvari, 1000 i. j. vitamina E te 60 mg/kg + 1000 i. j. Zn + vitamin E, pojedinačno, od 60. dana prije teljenja do 60. dana poslije teljenja. Krv je uzeta 60., 45., 30., 15. i 7. dan prije očekivanog teljenja, na dan teljenja te 60., 45., 30., 15. i 7. dan poslije teljenja. Prije teljenja krave su pokazale smanjenje razine leptina, inzulina, glukoze, vitamina E i cinka te povećanje razine neesterificirane masne kiseline u plazmi. Nakon teljenja razine leptina, inzulina, glukoze, vitamina E i cinka porasle su, a razina neesterificirane masne kiseline u plazmi bila je snižena. Nakon teljenja skupina T3 imala je povišene vrijednosti (P<0,01) leptina, inzulina i glukoze u odnosu na ostale skupine. Razina vitamina E u plazmi bila je veća (P<0,01) u skupinama T2 i T3; razina cinka bila je veća u skupinama T1 i T2. U skupini T3 opažena je viša (P