Supplying adequate nutrition to the cow is critical during the 60 days prior to calving and immediately after calving.
“Beef cattle can turn high fiber forages and food by-product residuals into protein food at a very effective rate,” says John Comerford, Pennsylvania State University professor emiritus of animal science, in a recent extension article. “For the cow herd, there is seldom a period during the year when the cow cannot meet her nutritional needs with reasonable quality grass, hay or stored forages. The exception for these nutritional needs is for the 60 days prior to calving and immediately after calving.”
Why Is There a Nutritional Challenge Prior To and After Calving?
Comford explains there are three major reasons why cows are challenged prior to and right after calving:
- The initiation of lactation
- The return to a fertile reproductive state
- The production of colostrum
He adds the cow’s age has an impact on these factors, and younger cows have more critical nutritional needs.
Lawton Stewart, University of Georgia (UGA) assistant dean for extension, and Uttam Saha, UGA Agricultural & Environmental Services Lab (AESL) program coordinator, explain there are three nutritional questions producers should consider as calving season approaches — depending on forage availability and quality.
- Does restricting feed in the last trimester decrease calf birth weights?
- Do you need more protein to go with hay?
- Are you underestimating crude protein and overestimating energy?
Does Restricting Feed in the Last Trimester Decrease Calf Birth Weights?
Stewart and Saha say yes, feed restriction will decrease birth weights. The problem is that birth weight is not the only thing it will affect.
Recent research has focused on fetal programming. Fetal programming is the concept that maternal stimuli or insults during fetal development have long-term effects on the offspring.
One of the most critical aspects of fetal programming involves the adequate nutrition, or lack thereof, of the dam. Research has shown minimal impact on calf birth weights; however, the restricted nutrition during the last trimester decreased weaning weights, finishing weights and hot carcass weights.
Additionally, research from Nebraska indicates heifers from nutritionally restricted cows reached puberty 14 days later than those with proper nutrition.
Do You Need More Protein to Go with Your Hay?
Stewart and Saha say possibly, however, protein is only half of the equation.
From April 1 to Oct. 1 of 2025, 773 bermudagrass hay samples were submitted to the UGA lab. The mean crude protein (CP) and energy (TDN) value was 11.1% and 55.7%, respectively. The illustration above represents the CP and TDN requirements of a brood cow throughout the production year. As cows enter the final trimester, their CP requirement is exceeded by the average bermudagrass sample, but the energy requirement falls short. More importantly, as they calve, enter peak lactation and the breeding season, the CP requirement is met, but the TDN falls tremendously short.
Do Producers Underestimate Crude Protein and Overestimate Energy?
Stewart and Saha say there is a tendency for producers to underestimate crude protein and overestimate energy.
“The cheapest money you will ever spend in a beef cattle operation is a forage test, guaranteed,” Saha says.
He explains a great illustration of this happened recently during the UGA Master Cattlemen’s Program. As part of the program, a free forage test was offered to participants along with a survey to estimate what producers thought the quality of the hay was prior to testing. This survey showed 83% of producers were underestimating the protein of their hay compared to the actual. This would result in purchasing a protein supplement when not needed.
For energy, 50% overestimated the level, resulting in depriving needed energy during late gestation and early lactation. In addition to the previously discussed fetal programming issues, this could also cause delayed breeding.
An example of overestimation of energy is illustrated the example above. The overestimation could likely result in breeding being delayed 42 days. The resulting loss in weaning weight could easily reach 80 lb., leading to an approximate $280 decrease in value per calf.
“Through forage testing, the producer would know to feed 4 lb./day of a supplement such as corn gluten feed. Based on a 25-cow herd, this could easily return $6,325 above cost. That is a no-brainer,” Saha explains.
Brood cow nutrition is a crucial part of a beef cattle operation. Between fetal programming and maintaining the proper calving interval, it is imperative for producers to pay close attention to the nutrients available in their forages, and if they meet the requirements of their herd.
Your Next Read:
Ensuring Quality and Nutrition: Three Easy Steps For Forage Analysis
9 Tips to Ensure Calving Season Success
Your Calving Prep Starts Here: The Essential Checklist
