Isn’t that how these diseases are generated in the first place?
No, livestock diseases were a problem long before vaccination. In fact it’s been hypothesized that the reason Europeans killed off Native Americans with disease instead of the other way around is that European livestock spread so much disease that it meant Europeans carried and were immune to a wide variety of diseases.
As for why livestock diseases are so common, it’s probably due to the obvious - the cramped conditions, often in close contact with other animals. Think of the classic Chinese wet market with animals from many different places stacked in cages on top of each other with fluids flying all over. That’s the real bio weapons lab.
No, livestock diseases were a problem long before vaccination. In fact it’s been hypothesized that the reason Europeans killed off Native Americans with disease instead of the other way around is that European livestock spread so much disease that it meant Europeans carried and were immune to a wide variety of diseases.
As for why livestock diseases are so common, it’s probably due to the obvious - the cramped conditions, often in close contact with other animals. Think of the classic Chinese wet market with animals from many different places stacked in cages on top of each other with fluids flying all over. That’s the real bio weapons lab.