Answer:
10%
Explanation:
We use the energy pyramid to figure this out:
.01% - A pex Predators
0.1% - Tertiary Consumers
1% - Secondary Consumers
10% - Primary Consumers
100% - Primary Producers
Cows are primary consumers, as they eat grass and hay (which are primary producers). So however much they eat of grass and hay, you multiply by 10% to get the total amount of energy that the cow gets.