Se. Scheideler, EGGSHELL CALCIUM EFFECTS ON EGG QUALITY AND CA DIGESTIBILITY IN FIRST-CYCLE OR 3RD-CYCLE LAYING HENS, Journal of applied poultry research, 7(1), 1998, pp. 69-74
Dried eggshell products from two egg breaker plants were compared to v
arious sources (limestone and oyster shell) and combinations of fine-
and large-particle calcium in two age groups of laying hens: third-cyc
le Babcock B300 and first cycle DeKalb Deltas. Particle size measureme
nts of the two dried eggshell products indicate a size pattern similar
to fine- or medium-particle limestone. The amount of large (> 4.0 mm)
particles found in the eggshell products were minimal, less than 5%.
Dried eggshell as the sole calcium source compared to combinations of
limestone and oyster shell showed no significant effect on feed intake
, egg production, or egg weight in the first-cycle hens. Rate of egg p
roduction was decreased in one of the eggshell treatments in the older
third-cycle hens without any change in feed consumption or egg weight
. Egg specific gravity decreased more in older hens fed the eggshell a
nd fine-particle limestone calcium sources. Egg specific gravity was i
mproved when the diet included large-particle calcium from either lime
stone or oyster shell. Dietary calcium digestibility was greatest for
the fine limestone and ground eggshell treatment groups. Calcium from
eggshells is highly available to support egg production in laying hens
but should be combined with a large-particle calcium source to suppor
t optimal eggshell quality.