She said it's tricky to estimate hay and fiber intake. So she estimates each cow's grazed forage intake on the basis of the cow's size. Stored feed can then be adjusted to get maximum dry matter intake from grazing. She said it is really trial and error based on the cow's production, condition, and overall health. Vitamin and mineral intake must be watched carefully in grazed herds, she said, especially calcium and phosphorus.
Grazed herds tend to be short on calcium in the spring when they are on lush cereals.
Tina tests forage and monitors the cows' body condition to determine rations for herds that use supplemental grazing. Rye samples are taken from a field just as they are grazed. To simulate a cow's grazing, she tears off the plants by hand at the same height the cows graze. On the Horn's own farm, rye tested from 27 percent to over 30 percent protein last March. Cow condition should never be neglected at any stage, she said.