Knowing the nutritional needs of cows helps producers cost effectively meet those needs. Over feeding 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 is available, the two primary nutritional requirements of cows are CP and Energy (in the form of TDN). In normal weather, there are three primary influences on the daily requirements of both:
- Mature Weight
- Level of Milk Production
- Stage of Production
Cow-calf operations should assess where their cow herd is now in the production cycle and be proactive in making management decisions regarding feeding and supplementation. The example below follows a 1,300 lb. 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:
CP = 1.64 lb. per day
TDN = 11 lb. per day
The same 1,300 pound cow in the final third of pregnancy needs:
CP = 1.84 lb. per day
TDN = 13.3 lb. per day
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 lb. cow will have increased nutritional requirements based on how much milk she is producing:
If giving 25 lb. of milk per day at peak lactation, she will need:
CP = 3.4 lb. per day
TDN = 19.3 lb. per day
If giving 35 pounds of milk per day, she will need:
CP = 4.2 pounds per day
TDN = 22.2 pounds per day
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 our nutritional program correctly plays a huge role in reproductive performance and cow productivity.
Reference: Nutritional Requirements of Beef Cattle. OSU Cooperative Extension Fact Sheet E-974
Mark Johnson, OSU Extension beef cattle breeding specialist, discusses how to calculate how much hay cattle producers will need in the winter on SunUpTV from Oct. 26, 2024 at
