Feeding beef cattle during the winter can be a challenging experience if being profitable is also one of your goals. Proper nutrition is a key component for a successful cow/calf operation. Cows go through many physiological changes during a year. The winter/early spring feeding period is one of the most critical times to provide adequate nutrition for the cow because of her needs at calving time.
Feed usually accounts for the single largest input cost associated with beef cattle. The winter feeding period generally becomes the largest portion of this cost. Stored feeds such as hay normally cost producers 3-5 times as much as grazing a summer pasture or stockpiled feed in a paddock, when cost is calculated. It's therefore critical to keep the amount of stored feed fed to an acceptable minimum so costs are kept under control, but you must still feed enough hay to meet the nutritional needs of the cow. We must maintain the cow's dietary needs if strong healthy calves are to be born in the spring and also get cows rebred in a timely manner to maintain acceptable calving intervals.
So, we quickly see how over feeding becomes costly, but don't ever forget that under nourished cows may be a disaster. Under nourished cows are ones not receiving enough nutrients from their feed. Notice I did not say, its cows not being fed enough hay. Cows can be under nourished even though they are eating all they can eat. Feeding the correct quantity of hay is important, but feeding the correct quality of the hay during each production stage is the key.
We often use the figures 2.5 - 3% of a cows body weight as the amount of dry matter (DM) a beef animal needs per day. So, a 1300 lb. cow would require approximately 33-39 lbs. of DM each day. Don't forget this is a DM calculation. To calculate the amount of hay we must actually feed we must account for the moisture in the hay. Most stored hay will be roughly 90% DM so we divide our 33-39 lbs. by 90% (.90) and get an as fed amount of 37-43lbs. of hay per day for our 1300 lb. cow.
Here's the catch. Doing these calculations still does not assure us the proper amounts of nutrients are being fed. Remember we said cows can starve eating all they could eat. Quality of hay must be accounted for to ensure the nutrients being fed are adequate. Poor quality hay has high percentages of non-digestible (neutral detergent fiber-NDF) material in it. Because of this a cow can not eat more than about 1.5% of her body weight in NDF. Poor quality forage does not pass through the rumen as quickly as high quality forage, hence the cow is full but still lacks the nutrients she needs to maintain productivity.