By Ragnarok.Sekundes 2013-01-31 07:15:29			
			
						
                     
                 
                Base is 5 per feed, every level above your skill is +1.
So 86 synth will give 6 per feed at 80 skill while an 90 would give 10 but since 5 is as low as it will go, even a item that requires only 15 will still give 5 per feed.  It's quite noticeable when you're leveling.  Get skill up, amount reduces by 1.
Er slight correction, it's too early ^^;