Effects of Hybrid and Maturity Stage on in Vitro Rumen Digestibility of Immature Corn Grain

Figures & data

Table 1. Whole plant and corn grain dry matter and chemical composition of corn grain collected at different sampling times from different hybrids.

	SAMP						HYB				SEM	P
	T1	T2	T3	T4	T5	T6	Gigantic	Klips	Y43	9575	SAMP	HYB	HYB×SAMP
WP_DM, %	33.05^a	34.22^b	33.15^a	37.68^c	41.34^d	45.59^e	34.75^a	38.08^c	36.06^b	41.13^d	0.6159	0.0001	0.0002	0.0676
GR_DM, %	47.64^a	52.33^b	55.49^c	60.25^d	62.76^e	67.12^f	53.66^a	60.06^c	57.00^b	59.67^c	1.0560	0.0001	0.003	0.1840
CP, % DM	9.23^b	9.20^b	8.83^a	8.86^a	8.74^a	8.81^a	9.00^b	9.08^b	9.62^c	8.08^a	0.04197	0.0001	0.0001	0.0001
Starch, % DM	67.47^a	70.35^b	71.69^c	72.82^d	72.94^d	72.70^d	71.08^b	70.23^a	70.24^a	73.77^c	0.2551	0.0001	0.0001	0.0001
Sugar, % DM	10.70^d	8.76^c	7.13^b	6.99^b	5.84^a	5.49^a	8.01^c	7.22^b	8.03^c	6.68^a	0.2432	0.0001	0.0004	0.0001
CF, % DM	3.86	3.70	3.82	3.81	3.78	3.83	3.98^b	3.65^a	4.00^b	3.57^a	0.06151	0.1112	0.0008	0.0001
Ash, % DM	1.70^c	1.62^bc	1.51^ab	1.46^a	1.42^a	1.41^a	1.58^c	1.48^a	1.52^b	1.49^ab	0.01411	0.0001	0.0001	0.0001
Zein, % DM	2.20^a	2.28^ab	2.15^a	2.49^bc	2.48^bc	2.50^c	2.24^b	2.51^c	2.70^c	1.96^a	0.04583	0.0001	0.0001	0.3020
Zein, % CP	23.77^a	24.73^bc	24.28^ab	28.04^c	28.33^c	28.30^c	24.98^b	27.63^c	28.08^c	24.28^a	0.4842	0.0001	0.0001	0.2900
Zein, % starch	3.28^b	3.24^ab	3.01^a	3.44^b	3.41^b	3.45^b	3.15^b	3.57^c	3.84^d	2.66^a	0.06629	0.0001	0.0001	0.1173

SAMP, sampling date; HYB, hybrid; T1, sampling done after 95 days from seeding; T2, sampling done after 4 days from T1; T3, sampling done after 8 days from T1; T4, sampling done after 13 days from T1; T5, sampling done after 18 days from T1; T6, sampling done after 27 days from T1; HYB×SAMP, interaction between SAMP and HYB; WP_DM, whole plant dry matter; GR_DM, grain dry matter; CP, crude protein; CF, crude fat.

^a-fMeans with different superscripts in the same row differ significantly within SAMP or HYB (P<0.05).

Table 2. Correlation between main parameters measured on corn whole plant (only dry matter) and grain collected at different sampling times from different hybrids.

Item	GR_DM	CP	Starch	Sugar	Zein, % DM	Zein, % CP	Zein, % starch	DMD_7h	STD_7h	VFA	GP_b	GP_c
WP_DM, %	0.83^*	-0.46^*	0.60^*	-0.72^*		0.39^*	-0.39^*	-0.41^*	-0.59^*	0.48^*	-0.67^*
GR_DM, %		-0.34^*	0.64^*	-0.89^*	0.33^**	0.61^*		-0.63^*	-0.64^*	-0.75^*	0.55^*	-0.87^*
CP, % DM			-0.67^*	0.44^*	0.65^*	0.26^**	0.75^*				-0.37^*
Starch, % DM				-0.72^*			-0.41^*	-0.24^**		-0.49^*	0.50^*	-0.55^*
Sugar, % DM						-0.45^*		0.62^*	0.61^*	0.72^*	-0.54^*	0.86^*
Zein, % DM						0.90^*	0.97^*	-0.60^*	-0.64^*	-0.25^**		-0.45^*
Zein, % CP							0.81^*	-0.65^*	-0.73^*	-0.46^*	0.34^**	-0.68^*
Zein, % starch								-0.49^*	-0.54^*			-0.29^**
DMD_7h, %									0.86^*	0.61^*		0.80^*
STD_7h, %										0.55^*	-0.35^**	0.75^*
Starch_Kd, /h										0.46^*	-0.29^**	0.76^*
VFA, mmol/L												0.77^*
GP_b, /h												-0.50^*

GR_DM, corn grain dry matter; CP, crude protein; DMD_7h, dry matter digestibility after 7 h in vitro fermentation; STD_7h, grain starch digestibility after 7 h in vitro fermentation; VFA, volatile fatty acids; GP_b, maximum potential gas production; GP_c, gas production rate; WP_DM, whole plant dry matter; starch_kd, starch digestion rate.

*P<0.01

**P<0.05. Only significant values are showed.

Table 3. Dry matter and starch digestibility, fermentation rate of starch and volatile fatty acids with their molar percentage.

	SAMP						HYB				SEM	P
	T1	T2	T3	T4	T5	T6	Gigantic	Klips	Y43	9575	SAMP	HYB	HYB×SAMP
DMD_7h, %	45.42	41.14	39.68^d	37.66^c	36.07^b	35.18^a	39.31^c	36.72^a	37.72^b	43.03^d	0.6172	0.0001	0.0001	0.0733
STD_7h, %	55.22	51.39	48.46^d	45.92^c	44.61^b	41.85^a	48.76^b	45.11^a	45.50^a	52.28^c	0.9591	0.0001	0.0009	0.1648
Starch_K^d, /h	0.0540	0.0483	0.0445	0.0413	0.0397	0.036	0.0452	0.0404	0.0408	0.0498
VFA, mmol/L	39.60	38.27	37.28^d	35.32^b	35.95^c	34.27^a	36.89^bc	35.94^a	37.23^c	36.52^ab	0.4991	0.0001	0.0764	0.0617
Acetate, % mol	64.27	64.48	65.05^b	65.20^bc	65.42^bc	65.53^d	64.82^a	65.17^b	64.60^a	65.37^b	0.1362	0.0001	0.0051	0.0994
Propionate, % mol	22.83	22.43	21.93^b	21.91^b	21.67^ab	21.45^a	22.40^b	21.93^a	22.19^ab	21.95^a	0.1138	0.0001	0.1181	0.0750
Butyrate, % mol	10.61	10.72	10.58	10.73	10.58	10.68	10.66^a	10.49^a	11.02^b	10.43^a	0.0923	0.6338	0.0001	0.7920
Isobutyrate, % mol	0.21	0.27	0.31	0.11	0.18	0.16	0.19	0.24	0.24	0.17	0.0699	0.1977	0.6762	0.3890
Valerate, % mol	1.01	1.03	1.03	1.03	1.01	1.03	1.01	1.05	1.05	0.99	0.0234	0.8447	0.1239	0.5754
Isovalerate, % mol	1.07^a	1.08^a	1.09^a	1.12^a	1.11^a	1.15^b	1.07^a	1.13^b	1.13^b	1.08^a	0.0205	0.0487	0.0045	0.6660

SAMP, sampling date; HYB, hybrid; T1, sampling done after 95 days from seeding; T2, sampling done after 4 days from T1; T3, sampling done after 8 days from T1; T4, sampling done after 13 days from T1; T5, sampling done after 18 days from T1; T6, sampling done after 27 days from T1; HYB×SAMP, interaction between SAMP and HYB; DMD_7h, grain dry matter digestibility after 7 h in vitro fermentation; STD_7h, grain starch digestibility after 7 h in vitro fermentation; VFA, volatile fatty acids.

^a-dMeans with different superscripts in the same row differ significantly within SAMP or HYB (P<0.05). Measurements were made after 7 h in vitro fermentation of corn grain collected at different sampling times from different corn hybrids

Table 4. pH and kinetic parameters of gas production calculated from a 72 h in vitro fermentation of corn grains collected at different sampling times from different hybrids.

	SAMP						HYB				SEM	P
	T1	T2	T3	T4	T5	T6	Gigantic	Klips	Y43	9575	SAMP	HYB	HYB×SAMP
pH	6.34	6.34	6.34	6.33	6.34	6.33	6.34^b	6.34^b	6.35^b	6.31^a	0.0075	0.9515	0.001	0.8501
GP_b, mL/g OM	380.92^a	381.83^a	387.35^b	386.33^b	392.33^c	387.13^b	385.84^a	385.81^a	384.98^a	387.29^b	2.0963	0.0001	0.4832	0.4054
GP_c, h^–1	0.0553^e	0.0530^d	0.0517^c	0.0503^b	0.0493^a	0.0491^a	0.0521^c	0.0502^a	0.0516^b	0.0519^b	0.0003	0.0001	0.001	0.0017

SAMP, sampling date; HYB, hybrid; T1, sampling done after 95 days from seeding; T2, sampling done after 4 days from T1; T3, sampling done after 8 days from T1; T4, sampling done after 13 days from T1; T5, sampling done after 18 days from T1; T6, sampling done after 27 days from T1; HYB×SAMP, interaction between SAMP and HYB; GP_b, maximum potential gas production; OM, organic matter; GP_c, gas production rate.

^a-eMeans with different superscripts in the same row differ significantly within SAMP or HYB (P<0.05).