. 2020 Aug 12;99(11):5792–5801. doi: 10.1016/j.psj.2020.06.082

Table 4.

Effect of dietary Ca and available P levels and phytase on eggshell quality traits of single-comb White Leghorn hens from 68 to 78 wk of age.¹^,²

Weeks of age	Pre-experimental period	Experimental period
Weeks of age	68	70	72	74	76	78
Eggshell breaking strength, kgF
PC	3.41^a,b	3.77^a	3.68	3.40^a,b	3.37^a	3.58^a
NC1	3.41^a,b	3.68^a	3.55	3.10^b	3.20^a,b	3.50^a,b
NC2	3.21^b	2.76^b	3.44	3.09^b	2.83^b	3.02^b
NC1 + BSP	3.73^a	3.86^a	3.91	3.46^a,b	3.68^a	3.70^a
NC2 + BSP	3.87^a	3.50^a	3.80	3.67^a	3.40^a	3.77^a
Pooled SEM	0.200	--------------------------0.180-------------------------
P-value
Diet	0.134
Diet × Age		--------------------------0.001-------------------------
Specific gravity
PC	1.082	1.084^a	1.082^a	1.082	1.082^a	1.080^a
NC1	1.081	1.081^a,b	1.079^a,b	1.081	1.082^a	1.081^a
NC2	1.080	1.078^b	1.078^b	1.080	1.077^b	1.076^b
NC1 + BSP	1.082	1.083^a	1.081^a,b	1.081	1.082^a	1.080^a
NC2 + BSP	1.081	1.084^a	1.081^a,b	1.083	1.082^a	1.080^a
Pooled SEM	0.001	--------------------------0.006-------------------------
P-value
Diet	0.720
Diet × Age		--------------------------0.009-------------------------

^{a, b}Treatment means with no common superscript within each column for each measure differ significantly (P ≤ 0.05).

Treatment means for eggshell breaking strength and specific gravity at each week of age were calculated with 20 replicates.

PC, positive control (nutrient-adequate diet with 3.5% Ca and 0.35% available P), NC1, negative control 1 (the PC reduced in Ca and available P by 0.187 and 0.159% of the diet, respectively); NC2, negative control 2 (the PC reduced in Ca and available P by 0.231 and 0.275% of the diet, respectively); and NC1 + BSP and NC2 + BSP, the NC diets supplemented with Buttiauxella sp. phytase at 600 FTU/kg.