Table 4.

Effects of different dietary CP levels on the reproductive organ and ovarian follicle development of laying ducks at the end of the trial (61 wk).

Variables	CP level (%)1					SEM	P-values
	17.5	16.5	15.5	14.5	13.5		ANOVA	Linear	Quadratic
Initial Body weight (kg)	1.48	1.47	1.49	1.48	1.49	0.005	0.801	0.601	0.763
Final Body weight (kg)	1.48	1.47	1.48	1.46	1.51	0.007	0.128	0.240	0.123
Liver weight (g)	49.7	50.5	49.8	52.3	45.8	0.954	0.308	0.393	0.260
Oviduct length (cm)	53.2	58.2	57.1	53.2	58.3	0.849	0.103	0.400	0.668
Oviduct weight (g)	57.5	54.1	54.6	52.8	53.3	0.672	0.212	0.041	0.076
Ovarian weight (g)	51.7a	52.3a	42.9a,b	39.7b	41.8a,b	1.561	0.012	0.002	0.006
Number of POF	4.83	5.08	5.25	4.83	4.67	0.122	0.604	0.507	0.312
Total POF weight (g)	42.0a,b	43.5a	36.2a,b	33.1a,b	31.4b	1.665	0.048	0.005	0.021
Mean POF weight (g)	8.63a	8.76a	6.92a	6.83b	6.72b	0.283	0.019	0.002	0.009
Number of SYF	11.6	10.4	9.58	6.67	7.92	0.643	0.104	0.012	0.039
Total SYF weight (g)	2.05a,b	2.44a	1.83a,b	1.30b	1.40a,b	0.137	0.036	0.009	0.031
Mean SYF weight (g)	0.190	0.213	0.199	0.177	0.190	0.009	0.826	0.584	0.807
Number of LWF	14.5	12.9	11.6	13.8	13.3	0.810	0.854	0.788	0.700
Total LWF weight (g)	0.768	0.818	0.723	0.848	0.748	0.046	0.927	0.970	0.979
Mean LWF weight (g)	0.051	0.067	0.065	0.059	0.059	0.002	0.063	0.588	0.068

^a,bMeans within a row with differing superscripts differ significantly (P < 0.05). Abbreviations: LWF, large white follicles; POF, preovulatory follicles; SYF, small yellow follicles.

¹Mean of 6 replicates (2 ducks per replicate) per treatment.