Jeff Mattocks, Poultry nutritionist on digestive grit

Jeff is a poultry nutritionist who’s spent three decades working with pastured poultry producers. He’s done more than anyone else to raise awareness about the need to feed your chickens digestive grit. Digestive grit is very different to shell grit. To see pictures of the kind of stones he’s talking about, check out his article in the September 2025 issue of Chook Journal, a fully digital experience available now on our website chookjournal.com.au In this conversation Jeff explains:  * How digestive grit (insoluble for mechanical digestion in the gizzard) is completely different to shell grit/oyster shell (soluble source of calcium) * That most soil types do not contain enough rocks and stones to supply chickens with the amount of right-size grit they need to consume every month * His lightbulb moment when he discovered the importance of digestive grit * The mechanism by which rocks and stones benefit chickens (and all poultry)  * How digestive grit protects against intestinal worms * Why some worms are normal and actually healthy in chickens (as is some coccidiosis) * What types of stones you can use to DIY digestive grit since there's no ready-made product sold in Australia * What size grit for what age chicken  * How to start baby chicks on grit