What's all that residue on Lydia's hand?

Here is Lydia trying to show how dirty one's hands can get from rectal palpation. Thank heavens for those gloves! Despite the claim that these gloves can last a veterinarian through 200 cows without breaking, mine broke immediately after my first cow. How's that? Anyway it's really tiring to have to hold out your arm that is covered with shit, away from you so that you don't soil your overalls ( and have less to wash later on). Seriously, cow dung isn't so bad after all, other than the fact that it's a little too runny for my "taste" hehe.