Each hen requires around 4 grams of calcium a day, in order to get the 2 grams needed for one egg shell. In human terms, this is the equivalent of about 1.5kg of calcium per day (for a 70kg person), which is as much as you’d find in 1,500 litres of milk! This is one of the many reasons that a proper diet is so important for laying hens. EGG SHELL STRENGTH The egg shell is made primarily from calcium carbonate, known as “nature’s ceramic”, which is the same hard substance found in chalk, limestone and coral. Hens need a lot of calcium to produce strong egg shells. PART 1 A GOOD EGG NEEDS A GOOD SHELL, NOT JUST TO HOLD IT TOGETHER, BUT ALSO TO PROTECT IT FROM BACTERIA AND CONTAMINANTS. AN INTRODUCTION TO OUR FEATHERED FRIENDS 12 | THE CHOOK BOOK