Answer:
The benefit breeders get out of cows with greater muscle mass is that they can get almost 40% more edible meat from them.
Step-by-step explanation:
First of all, muscle mass in cattle is the source of meat to be consumed. Now, considering this. The greater the amount of muscle mass the bigger the amount of meat that the breeder can sell the cow for. In other words, more muscle mass means more profit. This could lead to up to 40% of the profit.