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Cow Feeding Program Impacts Fetal Development During Late Pregnancy

Muscle development occurs at two different stages of pregnancy. In mid pregnancy, the initial development of the muscle cells builds the base for further muscle development in late pregnancy. The number of muscle cells cannot be changed.

Associated with muscle development is the ability of the animal to marble (develop internal fat). Marbling improves meat quality. When nutrients are limited at this time, the total amount of muscle development and marbling is reduced.

The cow develops colostrum in the last five to six weeks of pregnancy. Colostrum is the first milk that provides passive immunity to the calf. All nutrients are required to develop a high quality colostrum. Vitamin E can only be passed on to the calf through the colostrum. It is not transferred to the calf prior to calving.

A minimum of 9% protein is required in late pregnancy. If grazing late season on over mature pasture, or fed a poorer quality hay, long term calf performance is impacted. Calves born to cows that did not consume adequate protein were 15 to 25 pounds lighter at weaning and had a 35 to 40 pounds lighter carcass weight when slaughtered.

Heifer calves were also impacted by cows consuming a low protein ration in late pregnancy. These calves took longer to start cycling and had a 10 to 13% lower pregnancy rate compared to those receiving a higher protein ration.


Inadequate nutrition can be very subtle. Poor nutrition can impact animal performance, health, and reproduction. A lower average weaning weight, a 2 to 5 percent higher open cow rate, or calves having more health problems at birth or later in life. Many times, it is attributed to “well, it was just the year” and not taken as an indication that there may be problems with the feeding program.

Spending time to sample feeds and balance rations can improve animal performance, reduce veterinary and drug costs and have heavier calves to sell. An investment that can pay big dividends.


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