High quality feeding translates into lower or no vet bills later! I'm not feeding goats, but household dogs, but consistently feeding an organic diet of human-grade hamburger, organic quinoa, vegetables, apples, pressure-cooked chicken feet, plus Dinovite (organic canine supplement), my 14-year old lab mix and 7-year old corgi mix are in robust health. Just had full vet work-up on both (mainly to verify my feeding program) and both sailed through with perfect values for blood, urine, fecal and physical exam. My vet is a Traditional Chinese Vet Med practice so no unnecessary vaccinations or prescription drugs either. This feeding regime works out to about $1/day per dog, but golly, are they happy and healthy! So it is worth the extra effort/expense to feed your animals well.

From what I recall about mangel beets is that they were a common livestock feed years ago but the farmer had to grind them up and mix them with other feed to make them palatable to their animals. There must be some nutrition that they were targeting by using them but as you found out, the beets must not be very palatable to them. Grinding up beets sounds like too much work to me, especially when we can get trace minerals from other sources.