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Research: Coarse limestone – better eggs

Limestone particles need to be a certain size to affect laying performance and egg shell strength, according to recent research at the Institute of Animal Science in Czech Republic.

A total of 120 ISA Brown hens aged 24–36 weeks and 120 ISA Brown hens aged 56–68 weeks were used to study the influence of limestone particle size and the animal's age on laying performance and egg quality.

Two diets were used: a diet containing calcium carbonate in fine limestone particles (diet LF with limestone particles <0.5 mm), and a diet containing calcium carbonate in coarse limestone particles (diet LC with 91% of particles larger than 0.8 mm and smaller than 2.0 mm).

Results

Hen-day egg production was higher and egg weight lower in young hens than in old hens. No increase in the shell breaking strength was observed.

It can be concluded that LC with a particle size of 0.8–2.0 mm should be considered rather than fine ground limestone when formulating diets for laying hens both in the early and the late phase of production.

Age                24-36 weeks       56-58 weeks
Limestone size LF (fine) LC (coarse) LF LC
Eggs/day 87% 89.4% 73.5% 79.9%
 
Egg weight 62g 63g 67g 68g
Shell weight - +2g - +2g
Shell thickness - +4 μm - +8 μm
Shell Ca content - +2mg - +2mg
Albumen height - +0.2mm - +0.3mm
Haugh units - +0.8 - +0.2

The full research can be obtained from ScienceDirect.

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