Horse is a vertebrate. Vertebrates are animals that are characterized by the possession of a backbone or spinal column. Vertebrates include mammals, birds, reptiles, amphibians, and fishes. All vertebrates have a basic body plan consisting of a stiff rod (vertebral column), with a hollow tube of nervous tissue (spinal cord) on top of it and the gastrointestinal tract under it.
Only a little amount of energy as 10% is transferred to the next trophic level. This is called 10% rule. So, in this case as the energy available at the secondary trophic level is 50 kilocalories and 10% of it is transferred into the tertiary level so it would be 5 kilocalories.
