Age-related changes in the shell gland and duodenum in relation to shell quality and bone strength in commercial laying hen hybrids

Table 2 Eggshell quality measurements from two layer hybrids

	LSL and LB					Statistical significance (P value)
	29 week (n = 46)	49 week (n = 46)	70 week (n = 40)	LB (n = 62)	LSL (n = 70)	Age	Hybrid	Age* Hybrid
Shell deformation test (µm)^c	60 ± 1.2^b	76 ± 2.3^a	80 ± 1.9^a	70 ± 1.6	73 ± 1.5	0.0003	0.5	0.4
Shell breaking strength (g)^c	4678 ± 91^a	4098 ± 91^b	4122 ± 124^b	4465 ± 85^a	4171 ± 77^b	0.0001	0.02	0.2
Shell weight (g)^c	5.70 ± 0.06^a	5.58 ± 0.07^b	5.85 ± 0.09^ab	5.76 ± 0.06	5.67 ± 0.05	0.02	0.3	0.8
Shell thickness incl. membrane (mm)^d	0.392 ± 0.0039^a	0.380 ± 0.0048^a	0.373 ± 0.0092^b	0.389 ± 0.0038	0.383 ± 0.0034	0.0003	0.9	0.8
Shell thickness excl. membrane (mm)^d	0.360 ± 0.0039^a	0.346 ± 0.0050^b	0.349 ± 0.0089^ab	0.360 ± 0.0039	0.352 ± 0.0035	0.03	0.5	0.3

Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) at three different ages (21, 49, 70 weeks) during the production period. Mean ± standard error. Values without a superscript or with the same letter (^a or ^b) do not differ significantly (P > 0.05)
^cEgg weight included as a covariate in analysis of shell deformation, shell breaking strength and shell weight
^dShell weight included as a covariate in analysis of shell thickness including and excluding membrane

ISSN: 1751-0147