Impacts of Limestone Multi-particle Size on Production Performance, Egg Shell Quality, and Egg Quality in Laying Hens

This experiment was conducted to evaluate the effects of single or multi-particle size limestone on the egg shell quality, egg production, egg quality and feed intake in laying hens. A total of 280 laying hens (ISA brown) were used in this 10-wk trial. Laying hens were randomly assigned to 4 treatments with 14 replications per treatment and 5 adjacent cages as a replication (hens were caged individually). The experimental treatments were: i) L, basal diet+10% large particle limestone; ii) LS1, basal diet+8% large particle limestone+2% small particle limestone; iii) LS2, basal diet+6% large particle limestone+4% small particle limestone; iv) S, basal diet+10% small particle limestone. The egg production was unaffected by dietary treatments. The egg weight in S treatment was lighter than other treatments (p<0.05). The egg specific gravity in S treatment was lower than other treatments (p<0.05). The eggshell strength and eggshell thickness in S treatment were decreased when compared with other dietary treatments (p<0.05). The laying hens in LS1 and LS2 treatment had a higher average feed intake than the other two treatments (p<0.05). Collectively，the dietary multi-particle size limestone supplementation could be as efficient as large particle size limestone.