Which of the following factors influences net energy requirements for pregnancy in beef cattle?

The stage of gestation is a crucial factor influencing net energy requirements for pregnancy in beef cattle because energy demands change significantly throughout the gestation period. During early gestation, the energy needs are relatively low; however, as the pregnancy progresses into the later stages, the developing fetus requires more nutrients for growth and development. This increased demand for energy particularly peaks in the last trimester when the majority of fetal growth occurs.

In contrast, while age of the cow, body condition score, and dry matter intake certainly play roles in overall nutritional management and can affect the efficiency of energy utilization, they do not directly account for the specific variations in energy requirements that correspond to different stages of pregnancy. Therefore, focusing on the stage of gestation provides the most direct understanding of how energy needs fluctuate during pregnancy.