Johnston & Jeff Hen Size Oyster Shell 25kgA constant supply of oystershell grit should be made available to your poultry birds, as it contains essential minerals and trace elements that help prevent the bird producing soft or poor quality eggshells. Its slow solubility also provides a steady calcium level, resulting in less bone breakage, improved feed conversion and healthier birds. Johnston & Jeffs Hen Size Oystershell Grit sits at 4 7mm in size, making it the perfect size for your poultry.