In the energy-balanced example, what is the final percentage composition of grain mix A in the total ration?

• A. 60% A and 40% B
• B. 40% A and 60% B
• C. 45% A and 55% B
• D. 55% A and 45% B

Answer: (D)

Energy balance in feed formulation means adjusting the proportions of feeds with different energy densities so the total energy of the ration exactly matches the target. Think of x as the fraction of grain mix A in the total mix. If E_A and E_B are the energy densities of A and B, the final energy per unit of the ration is x·E_A + (1 − x)·E_B. To meet the energy requirement E_req, you set x·E_A + (1 − x)·E_B = E_req and solve for x: x = (E_req − E_B) / (E_A − E_B). Since grain A provides more energy per unit than grain B, the solution will fall between 0 and 1 and tilt toward A when the target energy sits closer to A’s energy density. In this example, solving gives x = 0.55, so the final mix is 55% grain mix A and 45% grain mix B. This arrangement hits the energy target exactly without overfeeding or underfeeding energy; a higher share of A would overshoot, and a lower share wouldn’t reach the requirement.