Harvesting stages and additives affect fermentation characteristics, nutritional value, and animal preference for silages from Andropogon (Andropogon gayanus) grass

Figures & data

Table 1. Treatment layout

	Grass	Harvesting stages	AD
No			Molasses	Urea
1	Andropogon	Vegetative	-	-
2	“	“	+	-
3	“	“	-	+
4	“	“	+	+
5	“	Boot	-	-
6	“	“	+	-
7	“	“	-	+
8	“	“	+	+
9	“	Full bloom	-	-
10	“	“	+	-
11	“	“	-	+
12	“	“	+	+

No= Number, HS = harvesting stage, AD = Additives, VEG = Vegetative stage, BT = Boot stage, FB = Full bloom stage, without additive (-), with additive (+, 0.6% urea or 4% molasses) and both urea (0.6%) and molasses (4%) additive (+,+)

Table 2. Description of the scales used as indices of silage quality assessment

Scores	Smell	Color	Texture	Moldiness
1 Bad	Rancid and musty smell/pungent/	Dark/deep brown	Slimy	Highly moldy
2 Moderate	Irritative/offensive; alcohol/acidic	Brown/Medium	Slightly viscous /slimy	Medium
3 Good	Light acidic (pleasant)	Brown yellow	Medium(loose and soft, firm)	Slightly moldy
4 Excellent	Pleasant and sweet- acidic (very pleasant)	Light/green yellow/Olive green	Loose and soft, Firm	Without mold

Source: Ososanya and Olorunnisomo (2015).

Table 3. Nutrient composition (% DM) of the grass at different harvesting stages before ensiling

	Andropogon grass harvesting stage
	Vegetative	Boot	Full bloom
	Mean ± SE	Mean ± SE	Mean ± SE
DM (%)	25.06 ± 0.89^c	30.55 ± 0.63^b	37.14 ± 0.87^a
CP	9.56 ± 0.32^a	7.31 ± 0.05^b	4.80 ± 0.43^c
Ash	8.70 ± 0.01^a	6.59 ± 0.12^b	6.52 ± 0.06^b
NDF	70.00 ± 0.06^a	68.87 ± 0.30^b	67.40 ± 0.24^c
ADF	42.25 ± 0.15^c	44.17 ± 0.09^b	52.08 ± 0.57^a
ADL	5.57 ± 0.05^b	6.10 ± 0.03^b	9.86 ± 0.30^a

Treatments mean with different letters in a row are significantly different (P < 0.05). SE = Standard error, VEG = Vegetative, BT = Boot, FB = Full bloom, CP = crude protein, NDF = Neutral detergent fiber, ADF = Acid Detergent fiber, ADL = Acid Detergent lignin

Table 4. Andropogon grass silage physio-chemical properties in a different stage of harvest and additives

Parameter	HS	AD						P Value
		WO	WM	WU	WUM	**Mean	SE	HS	AD	HS*AD
Smell^a	VEG	4.00^a	4.00^a	2.67^bc	4.00^a	3.67^a	0.16	0.00	0.00	0.00
	BT	4.00^a	3.00^b	2.00^cd	4.00^a	3.25^b
	FB	1.00^e	2.33^bcd	1.00^e	1.67^de	1.50^c
	**Mean	3.00^a	3.11^a	1.89^b	3.22^a
Color^a	VEG	3.00^b	3.00^b	4.00^a	4.00^a	3.50^a	0.96	0.00	0.00	0.00
	BT	2.00^c	3.00^b	4.00^a	3.00^b	3.00^b
	FB	1.00^d	1.67^c	1.00^d	1.00^d	1.17^c
	**Mean	2.00^c	2.56^b	3.00^a	2.67^b
Texture^a	VEG	2.67	3.33	3.33	3.33	3.17^b	0.16	0.00	0.29	0.40
	BT	4.00	4.00	4.00	4.00	4.00^a
	FB	2.00	2.67	2.00	1.67	2.08^c
	**Mean	2.89	3.11	3.33	3.00
Moldiness^a	VEG	2.67	4.00	4.00	4.00	3.67^a	0.15	0.00	0.005	0.11
	BT	2.33	3.33	3.33	2.67	2.92^b
	FB	1.00	1.00	1.00	1.00	1.00^c
	**Mean	2.00^b	2.78^a	2.78^a	2.56^a
pH^b	VEG	5.55^abc	4.31^ef	5.73^ab	5.51^abc	5.27^b	0.11	0.00	0.00	0.009
	BT	4.77^de	4.10^f	5.07^cd	4.98^cd	4.72^c
	FB	5.81^ab	5.08^ba	5.98^a	5.35^bc	5.54^a
	*Mean	5.37^b	4.48^c	5.59^a	5.27^b

Means of interaction with different superscript letters in the same row and column for each parameter differ (P< 0.05); **, * = main factor mean value; ascore (1- bad; 2-moderate; 3-good; 4-excellent), WO= without additives; WM= with 4% molasses; WU= with 0.6% urea; WUM= with urea 0.6% and 4% molasses; VEG= vegetative stage; BT= boot stage; FB= full bloom stage; SE= standard error; bpH= silage pH in measured values; AD = Additives; HS = Harvesting stage.

Table 5. Nutrient composition (% DM) of Andropogon silage

Constituent	HS	AD						P-value
		WO	WM	WU	WUM	**Mean	SE	HS	AD	HS*AD
DM (%)	VEG	23.50	24.05	21.80	24.82	23.54^c	0.83	0.00	0.19	0.42
	BT	27.45	29.59	29.15	29.28	28.86^b
	FB	34.38	34.40	33.90	34.50	34.28^a
	*Mean	28.44	29.35	28.27	29.52
CP	VEG	8.91^ab	9.13^ab	9.38^ab	10.13^a	9.38^a	0.27	0.00	0.00	0.00
	BT	6.36^de	9.62^ab	8.58^bc	7.42^cd	7.99^b
	FB	5.36^ef	4.44^f	5.34^ef	5.32^ef	5.11^c
	*Mean	6.87^b	7.73^a	7.76^a	7.62^a
Ash	VEG	7.64^b	8.54^a	7.57^b	7.66^b	7.85^b	0.11	0.00	0.00	0.00
	BT	7.32^b	8.27^a	6.30^c	8.65^a	7.63^c
	FB	7.24^b	8.55^a	8.69^a	8.61^a	8.27^a
	*Mean	7.40^b	8.45^a	7.52^b	8.30^a
NDF	VEG	55.00^d	55.10^d	54.50^d	56.60^cd	55.27^c	0.61	0.00	0.00	0.00
	BT	60.30^b	59.70^bc	60.40^b	58.50^bc	59.73^b
	FB	68.41^a	65.51^a	61.00^b	61.03^b	63.69^a
	*Mean	61.23^a	60.10^ab	58.63^c	58.72^bc
ADF	VEG	35.48^g	45.82^c	42.02^e	43.49^d	41.70^b	0.25	0.00	0.00	0.00
	BT	42.61^de	35.50^g	31.35^h	40.33^f	37.45^c
	FB	54.25^a	45.47^c	54.05^a	48.03^b	50.45^a
	*Mean	44.12^a	42.26^b	42.47^b	43.95^a
ADL	VEG	5.38^c	5.41^c	5.26^c	5.22^c	5.32^c	0.33	0.00	0.21	0.00
	BT	6.53^bc	6.60^bc	7.82^ab	8.56^a	7.38^b
	FB	9.06^a	9.09^a	9.05^a	8.02^ab	8.82^a
	*Mean	6.99	7.03	7.37	7.28

Means of interaction with HS and AD type with different superscript letters in the same column and rows differ (P<0.05); **, * = indicates the main factors mean value, DM= dry matter of silage; CP= crude protein; NDF/ADF = Neutral/Acid detergent fiber; ADL= acid detergent lignin; WO= without Additives; WM= with molasses; WU = with urea; WUM= urea (0.6%) + Molasses (4%); SE.= standard error; VEG= vegetative stage; BT= Boot stage and FB= full bloom stage, AD = Additives, HS= Harvesting stage.

Table 6. The chemical composition (% DM basis) of the boot stage with different additives of Andropogon silage offered during preference and apparent digestibility study

Constitute	Treatment
	WO	WM	WU	WUM	SE
DM (%)	27.45^b	29.59^a	29.15^a	29.28^a	0.13
CP	6.36^c	9.62^a	9.94^a	7.42^b	0.27
Ash	7.32^b	8.27^a	6.30^c	8.65^a	0.15
NDF	60.30	59.70	60.40	58.50	0.92
ADF	42.61^a	35.50^c	31.35^d	40.33^b	0.22
ADL	6.53	6.60	7.82	8.56	0.54

WO = without additive, WM = with 4% molasses, WU = with 0.6% urea, WUM = with 0.6 urea and 4% molasses; SE = standard error, means with a different superscript in a row are statistically different at P<0.05.

Table 7. Preference and apparent digestibility of Andropogon silage at the boot stage of harvest

		Treatments
Experiments	Items	WO	WM	WU	WUM	SE
Preference of silage	^aDM intake (g/day/goats)	90.37^c	274.17^a	74.01^c	202.30^b	10.85
	RPI (%)	33.19^c	100.00^a	27.49^c	74.15^b	2.31
	Preference ranking	3	1	4	2
Apparent Digestibility	^bDM intake (g)	633.77^ab	762.87^a	503.06^b	655.79^a	44.19
	DMI/BW (%)	2.60^ab	3.13^a	2.07^b	2.67^a	0.17
	Digestibility (%)
	DM	49.21^c	63.19^a	61.65^a	55.39^b	1.02
	OM	49.85^c	63.79^a	63.26^a	56.29^b	1.00
	CP	50.42^c	73.10^a	74.44^a	57.92^b	0.90
	NDF	40.84^d	55.46^b	61.12^a	47.59^d	1.14
	ADF	48.00	50.15	43.78	46.99	2.72

Means within a row without a common superscript are significantly different (p<0.05); ADF=acid detergent fiber; CP=crude protein; DM =dry matter; NDF=neutral detergent fiber; OM=organic matter; s.e.m.=standard error of mean; WO= without additive; WM= 4% molasses; WU= 0.6% urea; WUM= 0.6% urea and 4% molasses; BW = Body weight, SE= standard Error; RIP= Relative Palatability Index

^aDM intake = cafeteria base of the four treatment DM intake per goat;

^bDM intake = DM intake per goat per treatment

Figure 1. Pearson correlation coefficients of Andropogon grass silage physical, chemical characteristics and, silage fermentation quality.

Figure 2. Biplot graph of principal component analysis for physical characteristics, fermentative, and chemical composition measures of silage harvested at different stages and treated with molasses and urea additives, NDF: neutral detergent fiber, ADF: acid detergent fiber. ADL: acid detergent lignin. Dim: Dimensionality Reduction. 1–12: the treatment number in Table 1.

Ososanya, T. O., & Olorunnisomo, O. A. (2015). Silage characteristics and preference of sheep for wet brewer’s grain ensiled with maize cob. Livestock Research for Rural Development, 27(1). http://www.lrrd.org/lrrd27/1/osos27012.htm

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