Things You'll Need
- Cattle
- Protein blocks
Instructions
Calculating Protein Needs
Figure out your herd's size and condition. Jane Parish of Mississippi State University says a cow's need for crude protein--measured as the protein in their feed plus the non-protein nitrogen--increases when they're nursing, putting on weight or recovering from giving birth; young, growing calves have particularly high needs. The more milk a cow gives or the more it grows, the more protein it will need; the book "Nutrient Requirements of Dairy Cattle" says maximum milk output occurs when crude protein is 23 percent of the cow's "dry matter intake."
Calculate the protein needs of your cow based on a table of nutrient requirements such as the one put out by North Dakota State University. The tables cover cows of different weights, different uses--beef cows and milk producers--and stages of life. For example, a 1,200 pound cow, four months after calving, giving 15 pounds of milk a day, would need 26.5 pounds of dry matter each day, and 8.6 percent of that should be crude protein--about 2.279 pounds or 1,033 grams
Calculate the amount of crude protein in whatever feed they're eating now. Ask your supplier for the nitrogen content, then multiply that by 6.25 to get the crude protein content. This figure is based on the amount of nitrogen found in a given quantity of protein.
Figure out how much extra protein your cow will need, and that will tell you the protein block requirement. The Australian government says that to provide 150 to 300 grams of protein to one cow per day would take a 250 to 500 gram block of 62 percent crude-protein content.