| Abstract | Vitamin A (retinol) i β-karoten bitni su mikronutrijenti kod teladi jer njihova dovoljna koncentracija u organizmu povećava postotak preživjele teladi. Koncentracija retinola i karotenoida u plazmi teladi se promjenom hrane povisuje ili snizuje, stoga je cilj ovog istraživanja bio utvrditi promjene u koncentraciji vitamina A i β-karotena u plazmi i hrani teladi do 42. dana starosti. Pokus je proveden na 12 teladi s farme visokomliječnih krava „Kapelna“ hranjene istim izoroteinskim i izoenergetskim obrocima. Krv je vađena na dan rođenja, nakon uzimanja kolostruma, te 3., 21., i 42. dana starosti, a istih dana uzeti su uzorci kolostruma, mlijeka, mliječne zamjenice i starter smjese kojima je telad hranjena. β-karoten i retinol su iz uzoraka ekstrahirani heksan i kvantitativno određeni HPLC metodom obrnute faze. Koncentracije β-karotena i retinola u kolostrumu su u prosjeku iznosile 73 i 137,3 μg/dL, u prijelaznom mlijeku 9,5 i 27,9 μg/dL, mliječnoj zamjenici 5,2 i 6μg/dL, dok je njihov sadržaj u starteru bio 16,4 i 57μg/g ST. Koncentracije β-karotena i retinola u plazmi prvog dana su u prosjeku iznosile 14,3 i 9μg/dL, trećeg dana 4,9 i 7,3μg/dL, 21. dana 7,4 i 8,4 μg/dL i 42. dana 3,9 i 9,8 μg/dL. Koncentracija β-karotena i retinola u hrani utjecala je na koncentraciju β-karotena i retinola u plazmi. Najvišu koncentraciju vitamina A sadržavao je kolostrum pa je i najviša koncentracija bila u plazmi tek rođene teladi. Telad s najnižom koncentracijom vitamina A u plazmi uginula je tijekom pokusnog razdoblja. |
| Abstract (english) | Vitamin A (retinol) and β-carotene are important micronutrients in calves since their adequate concentration in organism increases their survivability chances. Retinol and β-carotene concentrations in plasma of calves vary with the change of diet, and therefore, this study aimed to determine variations of vitamin A and β-carotene concentrations in plasma of calves up to 42 days of age. The animal trial was conducted on 12 calves at high milk production dairy farm „Kapelna“ fed the same isoprotein and isoenergetic diets. Blood samples were taken on the first (after calves drank colostrum), third, 21st and 42nd day of calves age, and at the same days, samples of diets (colostrum, milk, milk replacers, and starter feed mix) fed to calves were also taken. β-carotene and retinol were extracted with hexane from all samples and quantified using reverse phase HPLC method. Concentrations of β-carotene and retinol in colostrum were on average 73 and 137.3 μg/dL, in milk 9.5 and 27.9 μg/dL, milk replacer 5.2 and 6 μg/dL, while their content in starter mix was 16.4 and 57 μg/g DM, respectively. Concentrations of β-carotene and retinol in plasma of new-born calves were 14.3 and 9 μg/dL, on the third day of age 4.9 and 7.3μg/dL, on 21st day 7.,4 and 8.4 μg/dL and on 42nd day 3.9 and 9.8 μg/dL, respectively. β-carotene and retinol concentrations in the diet affected their respective concentrations in blood plasma of calves. Colostrum had the highest concentration of vitamin A and thus the highest concentration was in new-born calves. Calves with the lowest vitamin A concentration in plasma died before end of the trial. |
