It depends do you want to be a strictly equine vet or all around large animal vet?
        
                    
             
        
        
        
Well it extends 2,200 miles will that help?
        
             
        
        
        
Hey there,
Answer:
Van Helmont - He concluded that trees gain most of their mass by absorbing water
Priestley- He found out that plants release oxygen
Ingenhousz- He concluded that plants needs sunlight to produce oxygen. 
Hope this helps :D
<em>~Top♥</em>