Improving Egg Shell Strength During Late Production Period of Hens Fed Diets Supplemented with Different Vitamin D Forms and Levels

Abstract

EGG SHELL breakage causes an economic loss for egg producer, where 3% of the eggs laid produced with cracked shells or broken. This experiment was carried out to improve eggshell quality of eggs produced from aged chickens. Golden Montazah chickens that reached 11 month of age with average weight 1.45kg were randomly divided into nine groups . Groups one, two and three fed on control basal diets with zero levels of hydroxycholecaliferol (25-OHD3) and three levels from vitamin D3 (VD3) (2500, 3750 and 5000 IU) respectively, groups four, five and six fed on 0.04 mg∕kg of hydroxycholecaliferol (25-OHD3) and three levels from vitamin D3 (VD3) (2500, 3750 and 5000 IU) respectively, groups seven, eight and nine fed on 0.08 mg∕kg of hydroxycholecaliferol (25-OHD3) and three levels from vitamin D3 (VD3) (2500, 3750 and 5000 IU), respectively. The effect of supplemented layers diet with different forms and levels of vitamin D on mechanical, ultrastructure and chemical properties of eggshell during a late laying stage were tested. The results indicated that supplementing layer diets with 0.8 mg/kg hydroxycholecalciferol improved eggshell strength and ultrastructure of eggshell; moreover increased calcium contains eggshell and longer effective thickness (palsied layer) at the late stage of laying hens. The increasing total content of VD forms up to 0.13375 mg/kg diet causes an increase in the total amount of shell mass-produced by the hen, nevertheless other shell parameters didn’t adversely affect. In contrast, increasing the total content of VD sources mg/kg diet than the previous limit did not attain desirable achievement. The results recommend that adding 25 hydroxycholecalciferol at 0.8 mg/kg to avoid the deteriorating quality of eggshells at late ages of laying hens and avoid loss economic due to poor eggshell quality.