Are OBFA Minerals Suitable for Livestock Feeding?

In the early 1960s one of my dairy clients called me about a couple of problems he was having. Two of his heifers in late pregnancy had aborted calves about two weeks early. The calves survived but both heifers died. I recommended he take one to the Veterinary Diagnosttc Lab at the University of Missouri for an autopsy. The diagnosis came back "starvation” which really didn’t fit the circumstances on the farm. This shed little light on the problem so the actual cause was still a mystery.

Carl was also concerned that his animals were eating an unusual amount of minerals. He was feeding a ‘one-bag-fits-all’ (OBFA) mixed dairy mineral and they were eating all he would put out for them.

A feed store next to my Vet office sold products made the Morea Company of Crete, NE. Their main product was a feed supplement made from molasses. They also promoted a cafeteria style mineral program. Carl decided to try this new system.

The 12 compartment mineral feeder, on skids, was positioned in his cow lot, and he began loading it with the separate minerals. The cows watched him as he carried two 25# bags of minerals into the lot and emptied them into the feeder. When he entered again with another two bags, the cattle suddenly ran up, tore one of the bags from his hands and ate the entire contents of one of the bags. The main ingredient in that bag was zinc. Over the next week his cattle ate another bag of zinc and small amount of some of the other mineral. No more heifers aborted, the animals quit eating the OBFA minerals, and overall herd health improved. 

What was happening here? The previous season had not been the best crop year and the animals' preference for zinc indicated their feed was low in zinc. — this increased their appetite for zinc. — the OBFA mineral had a minimal amount of zinc, but was high in Calcium. — Calcium ties up zinc. (See Mineral Wheel) . Thus the excess calcium in every bite of mineral they ate increased the mineral imbalance and adversely affected the metabolic processes in the animals. The young heifers, pregnant and still growing, were the most vulnerable and suffered the earliest and most drastic symptoms.

In actuality, the herd was being force-fed excessive amounts of calcium which affected the absorption and utilization of other essential minerals. (See Mineral Wheel).

I suspect that if the exact same type and amount of minerals in this OBFA mix had been separated out and fed separately the animals would have adjusted for their own needs and no problems would have occurred.

This incident, from over 50 years ago, was the beginning of my education in mineral nutrition. It epitomizes the many pitfalls of feeding OBFA minerals. Since that time, I have never questioned the intrinsic nutritional wisdom that animals exhibit when given proper choices

Doc Sez: The goal of any mineral program should be to achieve balanced mineral adequacy for each individual with no excesses.