EFFECT OF DIETARY-SODIUM BICARBONATE AND SODIUM-BICARBONATE PLUS MAGNESIUM-OXIDE ON SILAGE INTAKE AND MILK-YIELD IN COWS

To study the effect of dietary sodium bicarbonate and sodium bicarbonate plus magnesium oxide on silage intake, milk yield and milk fat, twenty four lactating Friesian cows were allocated into three groups. The first group was treated with NaHCO3 (120 g/cow/day). The second group received NaHCO3 (120 g/cow/day) plus MgO (30 g/cow/day). The third was an untreated control group. The cows remained in feedloot and were fed with hay crop silage and corn silage, ensuring an intake of at least 10 kg of dry matter and concentrate according to milk yield, receiving 7.0, 7.9, and 7.9 kg of dry matter of concentrate in the control, the NaHCO3 and NaCHO3+MgO groups respectively. Silage intake was registered six times during 3 day periods. Each time, the difference between given and rejected silage was measured. The milk yield and milk fat were measured seven times every three weeks beginning on the first month of lactation. There was no significant effect on silage dry matter intake and milk fat with NaHCO3 nor NaHCO3+MgO but milk yield increased significantly (p < 0.05, 2.82 litres) in cows that received NaHCO3, remained aproximately constant in cows with NaHCO3+MgO (-0.35 litres) and decreased significantly (p < 0.05, -2.16 litres) in the control group.