Evaluation of venous blood gas analysis in milk fedcalves at different period of livestock cycle.

The acid-base balance and blood gases are essential tools in evaluating metabolism in calves. However the relationship between blood gas parameters, diet andgrowth should be further investigated. The aim of this study was to evaluate changes in acid-base status, blood gas and electrolyte parameters at different periods in veal calves livestock cycle. Ninety-six healthy cross breeding calves were enrolled in a farm in North-East Italy. Milk formula without NaHCO3 was administered during the first 40 days; 3 gr/L of NaHCO3 was administrated in milk replacer between 40-100 days; 5 gr/L of NaHCO3 was administrated in milk replacer between 100-150 days. Blood sampling were carried out from jugular vein at 1 day (t1), 60 days (t2) and 150 days (t3). Blood gas analysis was performed and pH, pCO2, pO2, HCO3, Base excess (BEecf), Ca++, Na+, K+ and lactate were analysed. One-way ANOVA and Tukey-Kramer post-hoc test were performed to assess differences between the blood gas parameters at the different periods. The main differences in blood parameters levels during the livestock cycle concerned pH, BEecf and HCO3. pH and BEecf mean values were normal in all periods according to reference ranges 7.35-7.45 and 1-11.8 mmol/l, respectively. pH mean value was statistically lowerin t1(7.41 ± 0.02) than in t2 (7.43 ± 0.03) and t3 (7.44 ± 0.02). BEecf mean values were statistically different in t1 (5.90 ± 2.15 mmol/l), t2 (8.47 ± 2.94 mmol/l) andt3 (10.67 ± 3.12 mmol/l). As regards HCO3 a significant effect was found between periods. Levels of HCO3 were in the normal range (28.1 – 33.7 mmol/l) in t1 (30.28 ± 1.97 mmol/l) and t2 (32.65 ± 3.02 mmol/l) but higher values were recorded in t3 (34.62 ± 5.12 mmol/l). The mean values of the other parameters were not statistically different between the periods. Our results indicate that only small variations on blood gas parameters can be found at different moments of breeding. Moreover the administration of NaHCO3 during breeding cycle doesn’t unbalance the normal levels of pH, but could affect levels of HCO3 and BEecf in venousblood.