A beef heifer that is close to parturition is down and won't get up, with a fetus that is alive and a recent change from grain to roughage. What should be done first?

In the scenario of a beef heifer that is down and won't get up close to parturition, with a live fetus and a recent dietary change from grain to roughage, checking calcium and phosphorus (Ca/P) levels is the first appropriate action to take.

This animal is likely experiencing hypocalcemia, often referred to as milk fever, which is common in lactating cows and can occur just prior to calving. The shift from grain to roughage may have influenced her calcium and phosphorus levels, particularly if she was not receiving adequate minerals before the sudden dietary change. Low levels of calcium can lead to muscle weakness and the inability to rise.

By checking her Ca/P levels, you can determine if the heifer is indeed hypocalcemic. If the levels are low, you can administer appropriate calcium supplementation, which would be a critical step in her recovery and ability to stand. This approach addresses a potential underlying metabolic disorder rather than simply providing symptomatic treatment or altering her diet again before assessing her immediate nutritional needs.