This article on the importance of oyster shell and grit for waterfowl is being republished from Acorn Hollow Bantams website with permission from Lou Horton.
Keepers of domestic waterfowl in particular have a greater tendency than keepers of land fowl do to forget that their birds have gizzards and that those gizzards play a vital role in their bird’s digestive process. One of the tradeoffs that birds make in their basic design is that they have a less extensive (and therefore lighter) digestive system. The gizzard allows the bird to use hard minerals kept in the gizzard to grind up the grains that make up a good proportion of their diets. It is interesting to note that the gizzards of species of ducks that subsist primarily on fish are typically smaller than those of species like the Mallard, which is the ancestor of all of our domestic ducks with the exception of the Muscovy.
My point here is that the gizzard is a vital tool that the domestic duck uses in digestion, but I fear that keepers often lose track of the fact that the gizzard must contain tiny rocks (for lack of a better term) in order to be effective. I suppose that we got that way because in the past, we have usually kept our ducks outside where they picked up what they needed without any help whatsoever. Times change, however, and some waterfowl raisers keep their birds in buildings or in raised pens for purposes of security and/or sanitation. Some young ducks probably never actually touch the ground during much of their lives. Those birds depend upon their keepers to give them access to the grit they require to aid in digesting their food. That generally means supplying them with the commercial product used by chicken raisers – granite grit.
What happens if one does not supply grit to birds that have no access to it in other forms? Those birds simply do not digest their feed as efficiently as they would otherwise. Are they more susceptible to crop impaction? Perhaps. Certainly they have a more difficult time getting the needed nutritional value out of their feed without the ability to break it down properly.
The other mineral that the keeper should supply for breeding birds is calcium. Calcium is required for the formation of the egg shells and normally is supplied in the form of ground up oyster shell. Do not rely on brands of breeder feed that claim that calcium is included in the feed. For the minimal costs involved, a small can of oyster shell in each pen of breeding birds is an obvious bargain.
One important thing to keep in mind about oyster shell is that it should only be supplied during the breeding season, starting a couple of weeks before one expects the first eggs. The consumption of excess calcium when the females are not laying can result in kidney damage so remove the oyster shell once the breeding season ends.
Oyster shell and grit for waterfowl By Lou Horton