Four diets with different sodium bicarbonate concentrations
were formulated to have þ150, þ250, þ400, and
þ500 DCAD levels with measured concentrations of þ155,
þ289, þ410, and þ491 meq/kg, respectively (Table 1).
Diets were calculated based on the difference of milliequivalent
of cations (NaþK) and anions (ClþS) per kg of DM. Diets
were separately prepared, according to each treatment, and
offered as total mixed ration composed of 60% concentrate,
and 40% roughage, based on requirements described by NRC
(2001). After an acclimation period of 14 days, cow BW was
measured, and the 72-day experimental phase started, which
was composed of four 18-day periods, in a Latin square
design. Each period consisted of 16 days of diet adaptation
and 2 days of data collection. Cows were fed ad libitum twice
daily (07:00 and 15:00) and orts, which were adjusted for a
desired amount of approximately 10%, were daily collected
and sampled for further DMI calculations. At the end of each
18-day period, cow BW was measured for diet adjustment.
Water was also provided ad libitum. Corn silage and concentrate
were sampled weekly for DM, which was obtained by
drying in an oven at 105 1C for 16 h, and ash determination by
incinerating the samples in a muffle furnace at 550 1C for 4 h
as outlined in AOAC (2000)