Every time I warm my GM up for yogurt, separating, whatever, it gets very goaty. This is fresh milk that tasted great when cold. Is this normal, or do I have a retarded goat/milk? I don't really like goaty yogurt. :sigh
The only thing I can think of is that the goaty taste is due to a contamination, the heating up incubates them to an amount that you can taste, if the milk sits in the fridge for a week it'll probably be goaty as well.
I've never had goaty milk, but I have had musty but only when I heated up the milk, changed the feed, and that solved the problem.
So I would just trouble shoot, is the buck running with the does? If so separate them and see if the milk is better. Are you washing the udder really well? Dirt/dust can cling at times. Warm soapy water, on the inside of the does legs, all over their udder and belly works well for me, followed by a teat dip at the end of each milking. Maybe there's milk stone on the pail,or pot, a good dairy soap or vinegar soak should do the job. These are just ideas I'm throwing out there.
When making yogurt and cheese, goatiness can ensue if your milk is more than a couple days old. Our Obers' milk starts to get goaty after about two weeks, but our La Manchas (which have higher butterfat, and therefore a stronger flavor) and my mom's NDs get goaty after a week.
No offence meant here but goaty tasting milk can most often be traced to unsanitary handling. People will usually blame the buck or something else first but that is usually not the case. Try washing the goat well and especially your hands before each milking and be sure to brush under the belly so that the dust, dirt and straw or hair doesn't fall into the milk. A filter will remove the debri but not the bacteria. Children seem to have more foreign objects in their milk bucket than adults do. Each foreign object that falls into the milk is bringing bacteria with it. This is true also of the dust that you are not seeing. The bacteria breaks down the milk releasing the goaty flavor.
Again - this is not meant to be an accusation but a suggestion as to where to look first.