The influence of supplemental chromium (Cr) on plasma cortisol, urea, calcium and phosphorus concentration were investigated in grazing cattle in caloric stress situation during the breeding season. Thirty primiparous zebu cows with 380 to 385kg of body weight were assigned to the following treatments: 15 cows fed supplemental Cr and 15 cows without supplemental Cr (Control). The cows were grazing in Brachiaria brizantha pasture. Chromium was supplied as high-Cr yeast Sacharomices cerevisae (1gCr kg-1). Chromium was added to mineral premix to provide 0.017% of supplemental Cr. Blood samples were collected in three periods by jugular venipuncture in heparinized tubes. Plasma was analysed for phosphorus, calcium, urea and cortisol. Data were analysed as a randomised block design. Premix daily consumption was 72.92g in the supplemented cow (12.40mg Cr/animal/day) and 77.84g premix in the non supplemented cow (0.78mg Cr/animal/day) groups. The concentration of cortisol in Cr-supplemented group was lower than that in control treatment (2.11mg dl-1 vs. 3.29mg dl-1). Plasma phosphorus (6.36mg dl-1 vs. 3.56mg dl-1) and calcium (12.87mg dl-1 vs. 9.02mg dl-1) were higher in Cr-supplemented group in the first period but no differences were found between groups in other periods. There was no difference in urea level (17.13mg dl-1 vs 17.70mg dl-1) between supplemented and control group.
chromium; cortisol; urea; calcium; phosphorus; caloric stress
