Since poultry have no teeth they have evolved to peck grit which helps to grind their food in the gizzard. Flint grit should always be available (in a separate container to the feed) so the birds can help themselves.
As well as flint grit, oystershell and limestone grit are also commonly fed. These are a source of calcium to provide strong shells. Heygates feeds have sufficient added limestone for birds which are fed ad-lib pellets or meal but it is recommended that flint grit is always available.
A supply of flint grit is important in helping to prevent Impaction problems (see below).
The easiest way to make sure all the grit requirements are met is to have mixed poultry grit accessible to your birds. This product is a mixture of flint grit, limestone grit and oystershell grit.
Gizzard and Crop Impaction
Mortality due to crop and gizzard impaction has become more common, particularly in the spring, as the number of free range hens as increased in recent years. Impaction has historically been more of a problem with intensively reared fattening birds which may gorge themselves on food without drinking enough.
Impaction occurs when the crop or gizzard fills up with long material which cannot be processed. This is usually long grass but can be other foreign material such as string. A common early symptom is lethargic birds which do not thrive and mortality rates are high as treatment is difficult.
Preventative measures include making sure that there is a constant supply of grit, keeping grass short and ensuring that there are sufficient drinkers.