Influence of different levels of dietary vitamin A on protein status in blood serum of lambs

Three groups of 10 weaned female lambs of average body weight 20-30 kg, were fed with hay and concentrates for a 99 day trial. The feed for groups I, II and III containd 10.000, 20.000 and 30.000 IU vitamin A/kg, respectively. Blood samples were taken on days 1,52 and 99 of the trial and the concentration of total proteins and their fractions were measured. At the beginning of the trial there no significant differences in the concentration of total proteins and their fractions among the groups. The increased quantity of vitamin A in the feed (20.OOO/U/kg) positively influenced the total protein concentration but the established increase was limited and further increase of dietary vitamin A was without effect. The increase of total protein occurred through an increase of alpha-and beta-globulin at the expense of albumin with stable b-globulin fractions. The decline of the A/G ratio was proportional to the increase of dietary vitamin A content.