Meeting Magnesium Requirements of Forage-fed Cattle
Magnesium is an essential nutrient for all animals. Mild deficiencies can result in reduced feed intake, poor diet digestion, and bone abnormalities. More severe deficiencies can cause a serious metabolic disorder known as “Grass Tetany.” Providing a palatable magnesium supplement with high biological availability is an effective strategy for meeting magnesium requirements of grazing cattle.
Supplemental Sources Of Magnesium
An experiment was recently conducted at Kansas State University to evaluate magnesium oxide as a supplemental source of magnesium when fed in a dry supplement or when added to NGS-Mag 12 blocks from New Generation Supplements. Six steers averaging 675 lbs. were placed into metabolism crates equipped with urine collection funnels. A total of three treatments were used: CONTROL (no supplemental magnesium); MAGOX (magnesium oxide combined with ground corn and molasses); NGS-Mag 12 (NGS -Mag 12 block). Two steers were allocated to each of the three treatment groups. The study was repeated three times, exposing each animal to each of the three dietary treatments.
The identical source of magnesium oxide was used to make NGS-Mag 12 blocks and the MAGOX supplement. NGS-Mag 12 blocks contained 12% crude protein and 2% magnesium. The MAGOX supplement was a mixture of 15% molasses, 26% magnesium oxide, and 59% ground corn, and contained 14.4% magnesium. NGS-Mag 12 blocks were offered to cattle continuously.
The MAGOX supplement was fed in sufficient amounts to provide the identical level of magnesium provided by the NGS-Mag 12 blocks. All steers were fed free-choice brome hay (10.0% crude protein; 0.14% magnesium) for a 7-day adaptation period. Records of daily forage consumption, fecal output and urine output were maintained throughout a 4-day collection period.
Total urine output was measured at 6-hour intervals, and a sample of urine was retained from each interval for determination of magnesium concentration. Total feed intake and fecal output were determined at 24-hour intervals for the 4-day collection phase. Finally, a sample of blood was taken from each animal daily for determination of blood plasma magnesium concentrations.