There are a number of different factors that determine the daily intake of a cow. The primary factors are cow weight, forage or diet quality, and stage of production. Cows that weigh 1,300 pounds will consume more on a daily basis compare to lighter weight cow that weighs 1,100 pounds. In addition, cows that are lactating will consume more feed than cows that are not lactating.

The better the quality of the forage, the more that forage the cows will consume. Cows will consume daily about 1.8% of their body weight of a poor quality forage, 2% of their body weight of a medium quality forage, and about 2.3% to 2.5% of their body weight of a high qulaity forage on a dry matter basis. Add about 0.2% to each of the numbers for a cow that is lactating.

Daily feed intake of cows on a dry matter basis consuming forages of differing quality when they are either gestating or lactating. When forage quality is low (52% TDN or less) and cows are not lactating, they will consume 1.8% of their weight on a dry matter basis. If the forage quality is average (TDN content between 52% and 59%), non-lactating cows will consume about 2.0% of their body weight daily on a dry matter basis of this forage. As an example, if the forage were 55% TDN and lactating cows on the average weigh 1,200 pounds, then it could be estimated that they would eat 28 (1200 pounds x 0.023) pounds of hay daily on a dry matter basis. If the hay were 88% dry matter, on an “as-fed” basis, cows would eat about 32 (28 pounds/.88) pounds daily. If there were 200 head of cows in the herd, it would take about 3.2 ton of this hay per day [(200 head x 32 lb/hd/da)/2000lb] not accounting for any waste. To take the use of feed intake one more step, the 1,200 pound cow the first 90 days post-calving, producing 20 pounds of milk at peak milk production needs to consume 2.7 pounds of protein daily on a dry matter basis (nutrient requirements are on a dry matter basis). If the hay is 8.0% crude protein and the cow consume 28 pounds of hay dry matter, she will eat 2.24 pounds of protein (28 pounds x 0.08). This hay after calving will need to be spiked with some protein post calving to meet the protein requirement. Likewise, if she needs 16.0 pounds of TDN daily, then 28 pounds of a forage that is 55% TDN yields 15.4 pounds of TDN consumed. This forage will need to be spiked with some energy. A small amount of a good quality alfalfa would likely fit the needs. If other feeds are needed, knowing this will allow time to shop around for the “best buy” of a supplement that fits the needs of the feeding program. It is interesting that a 1,200 lactating cow can eat 30 pounds per day dry matter of silage and if the silage is 35% dry matter, on an “as-fed” basis she could eat about 86 pounds daily. That’s a lot of silage, but remember the silage is 65% water. In addition, because corn silage is about 70% TDN, cows will not need a “full-feed” of corn silage to meet their energy requirement.