Effect of the Delivery Mode of Snail and Oyster Shells on Laying Hens’ Performance and Eggs Quality

Abstract

The effects of free choice-feeding of snail and oyster shells on eggs production and egg quality were assessed by using 72 ISA Brown hens of 60 weeks-old with an average laying rate of 83.3±3.59% at the beginning of the experiment. The hens were housed in Californian cages. They were divided into 4 dietary treatments based on oyster shell (Ob and Os) and snail shell (Sb and Ss). Hens in Ob and Sb treatments were fed with balanced diets containing oyster and snail shells, respectively. In Os and Ss dietary treatments, oyster and snail shells were delivered separately from the rest of the feed. Each diet was delivered to nine replicates cages of two hens each. The hens consumed significantly (P<0.05) more snail shell than oyster shell in the free choice-feeding. That feeding strategy significantly, decreased the eggshell thickness in hens fed oyster based-diets, but not in hens fed snail shell based-diets. It significantly reduced the efficiency (unit/egg) of metabolisable energy, crude protein and phosphorus. The free choice-feeding of both types of shells did not affect significantly the physical aspects of the internal and edible parts of eggs. In snail shell based-diets, the free choice-feeding appeared more convenient than balanced diet feeding to improve egg weight and to keep the laying rate and eggshell thickness