Kudzu (Pueraria montana var. lobata) age variability effects on total and nutrient-specific in situ rumen degradation

Figures & data

Table 1. Near-infrared reflectance spectroscopy (NIR) chemical composition of early (ES) and late season (LS) kudzu leaves incubated in experimental fistulated bovine during in situ rumen degradation study periods (DM basis).

Analysis	ES	LS
DM, %	88.2	88.5
CP, %	30.5	26.7
Available protein, %	28.9	24.9
ADF, %	18.4	26.2
NDF, %	27.3	45.7
Lignin, %	4.40	6.3
NEm, Mcal kg^−1	1.80	1.23
NEg, Mcal kg^−1	1.19	0.68
Ca, %	1.54	1.74
P, %	0.43	0.28
Mg, %	0.35	0.39
K, %	2.05	2.05
S, %	0.34	0.39
Cl, %	0.45	0.55
Lysine, %	1.55	1.25
Methionine, %	0.48	0.40

Table 2. Near-infrared reflectance spectroscopy (NIR) chemical composition of early (ES) and late season (LS) mixed grass hay fed to experimental fistulated bovine during in situ rumen degradation study periods (DM basis).

Analysis	ES	LS
DM, %	93.00	93.60
CP, %	11.40	14.00
ADF, %	40.60	39.50
NDF, %	63.70	63.60
Lignin, %	4.20	4.00
NEm, Mcal kg^−1	1.19	1.30
NEg, Mcal kg^−1	0.64	0.73
Ca, %	0.42	0.49
P, %	0.29	0.49
Mg, %	0.17	0.33
K, %	2.04	2.48
S, %	0.19	0.25
Cl, %	0.45	1.43
Lysine, %	0.40	0.49
Methionine, %	0.15	0.18

Table 3. Composition of free-choice vitamin and mineral supplement provided to experimental fistulated bovine during in situ rumen degradation study periods.

Ca, %	13.5
P, %	8.0
NaCl, %	13.5
Mg, %	4.0
K, %	0.1
Cu, ppm	2000
Mn, ppm	6000
Se, ppm	52.8
Zn, ppm	6000
Vitamin A, IU kg^−1	715,000
Vitamin D3, IU kg^−1	165,000
Vitamin E, IU kg^−1	880

Figure 1. Total in situ rumen dry matter disappearance (DMD) of early season (ES) and late season (LS) kudzu. *Indicates significant seasonal effect at a given incubation time (P < .05).

Figure 2. Total in situ rumen neutral detergent fibre (NDF) disappearance of early season (ES) and late season (LS) kudzu. *Indicates significant seasonal effect at a given incubation time (P < .05).

Figure 3. Total in situ rumen acid detergent fibre (ADF) disappearance of early season (ES) and late season (LS) kudzu. *Indicates significant seasonal effect at a given incubation time (P < .05).

Figure 4. Total in situ rumen crude protein (CP) disappearance of early season (ES) and late season (LS) kudzu. *Indicates significant seasonal effect at a given incubation time (P < .05).

Table 4. Kudzu age by in situ incubation time interaction effects for DM, NDF, ADF, and CP disappearance.

	In situ disappearance (%)
Inc. time (h)	DM	NDF	ADF	CP
0.25	NS	NS	NS	NS
1	NS	NS	NS	NS
12	*	*	*	*
24	*	NS	NS	*
36	*	NS	NS	NS
48	*	NS	*	NS
72	*	NS	NS	NS

Note: NS = no significance.

*Significant age by incubation time interaction (P < .05).

Table 5. Estimated nonlinear model parameter values of early (ES) and late season (LS) kudzu DM, NDF, ADF, and CP disappearance from a traditional fitting technique as influenced by in situ rumen fluid incubation time.

Component	Parameter	ES	LS
DM	D 0	70.21^a	54.99^b
	kd	0.10	0.11
	L	−0.38^a	0.65^b
	U	12.59^a	20.06^b
NDF	D 0	35.09	36.34
	kd	0.18	0.10
	L	4.20	5.69
	U	10.01^a	13.73^b
ADF	D 0	32.13	28.15
	kd	0.04	0.05
	L	4.3	6.4
	U	38.12	34.69
CP	D 0	40.18^a	35.12^b
	kd	0.04	0.03
	L	0.34^a	1.45^b
	U	20.16^a	30.3^b

^a D ₀ and U represent the digestible and indigestible fractions (% DM), respectively; k_d is the rate of digestion (% DM h⁻¹), L is the lag time (h) and t is the incubation time period (h).

^bLetters separate means based on P < .05 level by pair-wise comparison.