Is it really the case that urine and snake blood are nutritious?

Neither nutritious: These are 2 misconceptions. There is nothing in urine that can remotely be helpful in urine. Diabetic urine may contain sugar, but who would want to consume a diabetics urine for the sugar?. Some people spill protein in their urine but normal diets are the recommended source for protein. I suggest a piece of rare steak rather than snake's blood, it is cheaper & far easier to come by.

No: In fact snake urine and blood could contain salmonella. Furthermore, more often than not snake urine may be mixed with other components like must or fecal material. Don't use either.