عبدالله رمضانی قرا

A ten-week trial was carried out to determine the effect of different levels of nano-calcium carbonate (NCC) on egg production performance and egg quality. A completely randomized experiment was designed comprising 6 treatments, each with 4 replicates of 5 hens. Groups 1 and 2 were fed diets containing 8.06% and 6.045% calcium carbonate (CC) as positive and negative control respectively. Groups 3, 4, 5 and 6 received diets with 4.03% CC plus 2.015, 1.01, 0.252 and 0.126% NCC respectively. Egg production at 32 wks of age was significantly reduced by the lowest dietary supplementation with NCC (T6) (P<0.05). However, dietary treatments had no significant effect on egg weight, egg mass and FCR (P>0.05). The lowest egg shape index was recorded for the birds fed T6 at 31 and 33 wks of age (P<0.05). Hens fed T6 had the lowest egg specific gravity at 29 wks of age compared to those fed other diets. However, the lowest egg specific gravity at 33 wks of age be-longed to the birds which received T3. Dietary treatments had no effect on the Haugh unit. Hens on T6 had the highest yolk color at 33 wks of age compared to those receiving other treatments (P<0.05). It was concluded that it is possible to utilize NCC at the level of 0.252 to 2.015% instead of 4.03% CC in laying hen diets. However, longer term studies are suggested to determine the potential of nano-calcium carbonate, as a new calcium source, on egg production performance and egg quality in laying hens.