The content of Hb and the hematocrit value in blood and the total proteins, urea, glucose, free fatty acids, Na, K, Ca, Mg, Pa, Fe, Fe-binding capacity, Cu and Zn in the blood plasma of Warmblood horses during feeding with oat-hay or barley-hay rations over a period of 9 months

4 horses (Group A) received an oat-hay ration, through 9 months running, while 3 horses (Group B) were fed a barley-hay ration over the same period of time. Blood samples were collected and examined in 4-week intervals. All values considered, no differences were found to exist between the 2 groups with regard to Hb and haematocrit in blood as well as to protein, glucose, sodium, potassium, magnesium, iron fixation capacity, copper, and zinc in blood plasma. The urea level in plasma of Group A was higher than that in Group B, values being 5.76 +/- 0.64 mmol/l and 5.14 +/- 0.72 mmol/l. The same applied to free fatty acids, values being 150 +/- 83 mumols/l in Group A and 95 +/- 42 mumols/l in Group B. Calcium was 3.10 +/- 0.27 mmol/l in Group A and 2.92 +/- 0.26 mmol/l in Group B, while the A-B difference in inorganic phosphorus amounted to 1.62 +/- 0.65 against 1.99 +/- 0.77 mmol/l. Group A was inferior to Group B also with regard to iron in plasma, values being 28.6 +/- 2.42 mumols/l against 32.8 +/- 4.62 mumol/l. Causes underlying these differences are discussed in some detail.