Why do younger animals use energy more efficientlySolutionMo

Why do younger animals use energy more efficiently?

Solution

Most significant factor for more efficient food conversion in younger animals is composition of body mass. As animal grows older and heavier, amount and percentage of total fat in body increases. Since more energy is required to deposit one gram of fat than same amount of protein, gain per unit feed decreases (less efficient energy utilization) as animal grows older.

Note: Though protein mass also increases with age it decreases as a percentage of total body composition.