Abomasal infusion of ground corn and ammonium chloride in early-lactating Holstein-Friesian dairy cows to induce hindgut and metabolic acidosis

Next to rumen acidosis, other forms of acidosis may also affect lactational performance cows. Therefore, the effects hindgut induced via abomasal infusion ground corn, and metabolic NH4Cl, were studied in cows early lactation. Observations made on intake digestibility nutrients, lactation performance, energy N partitioning, blood acid-base status, fermentation characteristics. In a 6 × Latin square design, rumen-fistulated, second-lactation Holstein-Friesian dairy (48 ± 17 d milk) subjected 5 continuous infusions water as control, or solutions 2.5 mol NH4Cl/d, 5.0 3.0 kg corn/d, combination corn with either 2 NH4Cl levels, followed by rest. Treatment administered peristaltic pumps through lines attached cannula plug an line flexible disk (equipped holes allow digesta passage) secure its placement sulcus omasi. A total mixed ration consisting 70% grass silage 30% concentrate (on dry matter basis) was fed at 95% ad libitum individual The experiment conducted climate respiration chambers determine feed intake, balance. Abomasal affected status cows, but more strongly when corn. Metabolic (defined pH < 7.40, HCO3 concentration 25.0 mmol/L, negative base excess) observed corn/d + NH4Cl/d. associated decreased milk lactose content, body weight, retained protein, fecal excretion, increased urine tended decrease nutrients. Digestibility several nutrients likely result intake. resulted where from 6.86 without 6.00 regardless level. fermentation, evidenced volatile fatty acid concentrations. Hindgut except for starch, which increased, crude fat, not affected. No systemic inflammatory response observed, suggesting that epithelium severely acidic conditions barrier damage. yield, protein use efficiency, well reduced fat content excretion.