By Mark Johnson, Oklahoma State University Extension

As we near the winter months and the time of year when feeding harvested forage becomes the norm, we address the topic of daily nutritional requirements of the cowherd. Grazing and feed expenses account for about 42% – 52% of the input cost of a cow-calf operation. Knowing the nutritional needs of cows helps producers cost effectively meet their needs. Overfeeding or underfeeding both rob the profit potential from cow-calf operations. During the normal production cycle cows should gain some weight/body condition during the dry stages and lose some weight/body condition while nursing a calf. With that in mind, having cows at a BCS 5 – 6 going into calving season is optimum. This means that cows are in good shape and have ample energy reserves to draw upon when the “spike” in Crude Protein (CP) and energy (TDN) requirements occur post-calving as the cow begins lactation. Cows need to be in good shape at the beginning of calving season to reduce the rebreeding interval and stay on schedule to breed, calve and raise a calf to weaning each 12 months.

Assuming an ample supply of good quality water and an adequate vitamin/mineral supplementation program, the two primary nutritional requirements of cows are CP and TDN. In normal weather, there are three primary influences on the daily requirements of both:

1 – Mature Weight

2 – Level of Milk Production

3 – Stage of Production

Where cows are now in the production cycle and when they will start calving should be considered when making management decisions regarding feeding. The example below follows a 1,300-pound cow through a normal production cycle during the middle trimester of pregnancy, the final trimester of pregnancy, and the first 90 days post-calving based on her level of milk production.

During the middle third of pregnancy, the 1,300-pound mature cow needs:

The same 1,300-pound cow in the final third of pregnancy needs:

The increased nutritional needs reflect not only the cow’s maintenance requirements but also the increased growth and development of the fetus as calving draws near.

After calving, during the first 90 days of lactation, the same 1,300-pound cow will have increased nutritional requirements based on how much milk she is producing:

            If giving 25 pounds of milk per day at peak lactation, she will need:

If giving 35 pounds of milk per day, she will need:

In summary, the same cow has a dramatic rise and fall in protein and energy needs over the normal production cycle. Knowing these requirements is essential to cost effective feeding of the cow herd. Managing a nutritional program correctly plays a huge role in reproductive performance.