I taught blood trailing in the International Bowhunter Education Program (IBEP) as one of the chapters we taught. I used heavy condensed milk with dark red food coloring in a laboratory style squeeze bottle with long stem. It was a small 250 ml bottle. The blood trail was placed over 100-150 yds in woods. It worked fantastic and was quite realistic. The best part was the post discussion after going through the blood trailing exercise in classroom. The most interesting part of the discussion was how much "blood" did the deer lose based upon blood trail observation. The answers were all over the map! Pints to quarts! When I held up the bottle and it was still 1/2 full, class was always stunned. Then we discussed how much deer has to lose to go into trauma. I always felt this was prob the most informative chapter we taught since it provided perspective that can be retrieved mentally during future blood trailing. A "lot" of blood on ground is not as much as you think.