Eats Shoots and Leaves

I've always tried to place my apostrophes correctly and do get rather annoyed with a misplaced or missing punctuation mark. I'm having a dilemma which has occurred upon writing the feeding chart. Is it goats' milk or goat's milk? The apostrophe before the 's' implies that it is the milk from one goat, which I'm sure isn't the case, so it should be surely goats' milk indicating that the goats from which the milk came were plural. I will have totally lost my teenagers at this point and they will tell me to get a life. Any like minded individuals are recommended to read Lynne Truss's book 'Eats shoots and Leaves'.