The aim of the present experiment was to investigate the effect of diets providing different concentrate: lucerne hay ratios on venous blood gas in Holstein steers. Holstein steers (initial body weight= 261±15 kg, n=30) were adapted to experimental diets for one week. Then, for 120 days, steers were fed 10 kg of DM of diets differing in concentrate (155 g CP kg-1 of DM; 30% maize, 34% barley, 8% soybean meal, 5% sugar beet pulp, 10% wheat bran, 12% cottonseed meal, 0.3% CaCO3, 0.5% mineral and vitamin premix, 0.2% salt) to alfalfa hay ratios as 60:40 (C60:A40) and 80:20 (C80:A20) in a completely randomized design. Animals were fed the experimental diets (ad lib) as total mixed ration twice daily at 0800 and 2000 h. At days 60 and 120 of the experimental period, blood samples were taken from jugular vein 4 h after the morning feeding. Samples were analyzed for venous blood gas by Automatic blood gas system (AVL 995, Switzerland). Data were analyzed as repeat measures using the PROMIX of SAS and the means compared by the Duncan test (P< 0.05). The results of the present study indicated that blood HCO3 - and PaCO2 were not significantly affected by time when steers were fed high concentrate diets. However, HCO3 - was significantly affected by time (p< 0.05). Therefore it was concluded that the increasing of concentrate from 60 to 80 % could not cause a mixed metabolic acidosis in our condition.

Keywords