Elaborate on “milk is just filtered blood”, because the breast is not a kidney. This doesn’t jive with what I’ve learned about physiology. Lactocytes synthesize milk proteins such as lactalbumin and casein, they aren’t filtered out of the bloodstream.
I’d argue eggs aren’t chicken periods either, it’s not their endometrial lining.
Being no expert in the field at all, I'll post links that seem to contradict each other. In some circles, people seem to agree that basically all bodily fluids are either blood or a filtered derivative of blood. Others say this is not the case...
“Substitute X for Y” meaning removing Y and adding X is super weird to me. I always have to use a conscious effort not to interpret that as removing X and adding Y.