Most beef cows expected to calve in the early spring will soon be in the last trimester of gestation, and this is an important time to check nutrition.

Dr. Christina Hayes, Ph.D., with Purina Mills, says in the publication Bovine Veterinarian that 75% of fetal growth occurs in the last trimester. Therefore, nutritional demands are highest in pregnant cows during that time.

To support the performance of cow and calf, these demands must be met. The term fetal programming is used to decide how nutrition and environment affect the fetus while in the uterus, and it has been shown that fetal programming has a lifetime influence on the growth, health, and reproductive success of the animal.

During the last three months of pregnancy, there is a significant increase in nutritional needs for protein, energy, vitamins, and minerals, and it is important to meet those needs.

As calving time approaches, the rapidly growing fetus goes through final lung development critical to their preparation for breathing air. Once the calf is born, muscle fiber number is largely established for the rest of their life. Nutritional deficiencies at this time can reduce muscle fiber number and can affect calf growth, performance, and feedlot efficiency.

Good quality forage is essential, but it is difficult to meet all nutritional requirements with forage alone during certain times of the year. Most cows calving during January and February will need to be supplemented.

Analyze your hay to figure out the type and amount of supplement you will need for your gestating cows. If your cows are calving later in the year, such as March to May, the early spring grass is usually not enough to support pregnant cows, and supplementation may still be required.