Effects of a new multielement buffer on production, ruminal environment, and blood minerals of lactating dairy cows.

Twelve multiparous Holstein cows were used to evaluate the capacity of a multielement compound consisting mainly of northupite and sylvite to alleviate low milk fat percent. Possible mechanisms of action were assessed. Cows were arranged in a 4 X 4 Latin square design replicated three times. Basal diet was 55% concentrate:45% forage fed ad libitum. Dietary treatments were control, NaHCO3 at 1% of diet DM, and multielement buffer at 1 and 3% of diet DM. Feed intake and milk production were similar for all treatments. Milk fat percentages for the four treatments were 2.97, 3.21, 3.43, and 3.67%, respectively. A shift toward a higher molar percent of ruminal acetate and a lower molar percent of valerate appeared to coincide with changes in milk fat percentage. Milk protein percentage also was increased by supplemental multielement buffer. Ruminal fluid acidity was reduced by NaHCO3 and multielement buffer. Extent of in situ digestion of forage DM and cellulose was improved when cows consumed a buffering agent. Rate of corn silage digestion tended toward improvement. As mineral buffer was consumed, concentrations of Mg and K increased in ruminal fluid and blood. As dietary Na intake increased, ruminal and plasma Cl concentrations were depressed and plasma S and Ca were elevated.