Effect of supplementing magnesium oxide or brucite on plasma magnesium, rumen pH, rumen protozoa and plasma glucose levels in dairy goats

Abstract

This study determined the effect of supplementing magnesium oxide (MgO) or brucite on plasma magnesium, rumen pH, rumen protozoa and plasma glucose levels in dairy goats. Fifteen Alpine goats were used and assigned to three treatments: control (CON) = Rolled corn, cottonseed hulls, soybean meal, molasses, alfalfa hay and calcium carbonate; MgO = CON + 0.5 % MgO; and brucite = CON + 2 % brucite. The study lasted for 16 days with 10 days for diet adaptation and 6 days for sample collection. Samples of blood, urine, feces, milk, and ruminal fluid were taken. Concentration of magnesium in plasma from brucite was 22.3 % higher compared to the control. In addition, MgO and brucite had higher Mg values in feces (28.9 % and 95.5 %, respectively) and urine (58.3 % and 45 %, respectively). Brucite decreased rumen pH, ruminal protozoan population and dry matter intake compared to other treatments. Milk production and milk fat and protein were not affected by Mg treatments, but blood glucose was increased with MgO. Overall, results showed that at least in a relatively short-term, MgO can be used in goat diets as compared to the control treatment and brucite, kept dry matter intake without reducing rumen pH and rumen protozoa.