Abomasal infusion of corn starch and β-hydroxybutyrate in early-lactation Holstein-Friesian dairy cows to induce hindgut and metabolic acidosis

The objectives of this study were to induce hindgut and metabolic acidosis via abomasal infusion corn starch β-hydroxybutyrate (BHB), respectively, determine the effects these physiological states in early-lactation dairy cows. In a 6 × Latin square design, rumen-fistulated Holstein-Friesian cows (66 ± 18 d milk) subjected 5 continuous treatments followed by 2 rest. 3 factorial with levels BHB. infusions water as control, 1.5 kg starch/d, 3.0 8.0 mol BHB/d, starch/d + or BHB/d. A total mixed ration consisting 35.0% grass silage, 37.4% 27.6% concentrate (on dry matter basis) was fed at 90% ad libitum intake individual experiment conducted climate respiration chambers facilitate determination energy N balance. Fecal pH decreased each level infused into abomasum 6.49, 6.00, 5.15 0.0, 1.5, suggesting that induced infusion. No systemic inflammatory response observed permeability intestine epithelium not affected more acidic conditions. This associated digestibility nutrients, except for crude fat NDF, which affected. Induced did affect milk production composition balance, but increased efficiency. Abomasal BHB resulted compensated acidosis, characterized clear disturbance acid-base status (i.e., blood CO2, HCO3, base excess, tendency urinary pH), whereas remained within physiologically normal range. concentrations plasma, both well below critical threshold values subclinical ketosis. result abomasally BHB, retained body fat, response, intestinal permeability.