Why would you think that? Larger animals are usually much more energy efficient for various reasons - less surface area to radiate heat, and economies of scale with larger organs.
I believe you, but I'm very surprised. That has larger animals almost universally less efficient than smaller animals, which is the exact opposite of the expected efficiency due to Kleiber's law: https://en.wikipedia.org/wiki/Kleiber%27s_law
>a cat, having a mass 100 times that of a mouse, will have a metabolism roughly 32 times greater than that of a mouse.
And yet this is saying that a mice sized animal should be expected to have the same, or perhaps even better Feed conversion ratio than a cat sized animal.
The larger livestock will usually have a much longer lifespan. It has to keep its flesh heated above ambient for that entire lifespan. If Mouse A lives 100x longer and puts on the same weight and achieves the same stature as Mouse B, it's spent ~100x as much energy getting to the same physiological place as Mouse B.
Cows are slaughtered at 80 weeks while chickens are slaughtered at 6 - 8 weeks. That extra order of magnitude of basal metabolic rate is where the energy gets consumed.
Not really. There's a basic thermodynamic inefficiency as organisms get larger, and consume farther away from the energy source, in this that being the sun.
