Mares nursing fillies

Question
Lynne my name is John and I just traded two mares with fillies on there side.. One is three weeks old the other four weeks old.. The mare of the three week old has a hurt leg from stone hoff I believe is what the vet said but her milk bag does not look like she is producing alot of milk comparing her to the mare with the four week old mare.. I just noticed this today and the filly looks healthy but is there any thing I can do and how to check and see if she is making milk.. I know the gentleman who I got the horses from was giving the mare penaciline shots for the infection would this maybe also cause a problem with her not producing enough if any milk?? Thanks for the help John Pearce

Answer
Dear John

If the filly is an appropriate weight and looks healthy you are probably OK. The size of a mares bag is not in direct proportion to how much milk her offspring is getting.  The filly's condition is a much better indicator. If in doubt, you can always set up a creep feeder; but be careful not to over do that.  Some individuals are more likely to develop epiphysitis than others.  Creep feeding too much protein is a major contributor to this problem.  From what you have told me, I would be more worried about the mare's injured leg. What did you vet propose doing about that?