Table 4.

Weight of the eggs (in g) produced by laying hens fed rations containing different concentrations of caffeine for 12 weeks.

Caffeine in diet	Experimental period
	4 weeks	8 weeks	12 weeks
0 (control)	66.2 ± 1.06	66.4 ± 1.14	64.3 ± 0.96a
150 ppm	65.0 ± 1.03	65.5 ± 0.92	64.1 ± 0.80a, b
300 ppm	64.1 ± 0.98	63.1 ± 0.82	64.1 ± 1.04a
450 ppm	64.2 ± 0.73	64.3 ± 1.09	60.5 ± 1.07b
p	n.s.	n.s.	<0.05

Data are shown as mean ± SEM.

^{a, b}Different letters in the same column show significant difference (p < 0.05, ANOVA followed by Tukey test).

n.s., non-significant.

n = 24.