Effect of ryegrass hay and ryegrass silage, cut at two stages of development, on nutrient digestibility, nitrogen balance, and purine derivative excretion in growing sheep

Figures & data

Table 1. Chemical composition (g/kg DM) and protein fractions according to the Cornell Net Carbohydrate and Protein System (CNCPS) of ryegrass hay (H) and ryegrass silage (S) at two maturity stages (21 or 35 days) and a concentrate supplement (CS).

Item	H21	H35	S21	S35	CS^a
Dry matter^b(DM)	946	954	240	220	923
pH			4.0	4.1
Chemical composition
Ash	125	170	150	165	180
Organic matter	845	830	850	835	820
Crude protein	191	184	159	159	318
Fraction A, %^d	12.0	10.2	19.3	16.8	10.5
Fraction B1, %^d	8.2	5.5	13.4	10.2	3.5
Fraction B2, %^d	49.8	41.6	51.2	38.9	80.1
Fraction B3, %^d	17.0	17.5	13.8	15.3	4.2
Fraction C, %^d	13.0	25.1	8.0	13.1	1.7
Ether extract	25.0	20.0	20.0	15.0	28
NFC^c	121.0	52.0	179.0	150.0	336.0
Neutral detergent fibre	508	574	510	511	138
Acid detergent fibre	372	417	295	304	71
Acid detergent lignin	30	29	25	25	24
Volaty fatty acids (mol/100 mol)
Lactic acid			64	62
Acetic acid			11	12
Butiric acid			21	22
Lactate/acetate ratio			5.8:1	5.1:1

^aCS = Corn grain and soybean meal (30:70)

^bDM = expressed of fresh matter

^cNon-fibre carbohydrate (OM – CP – NDF – EE).

^dFraction A, non-protein nitrogen; B1 buffer-soluble protein; B2, buffer-insoluble, neutral detergent-soluble protein; B3, neutral detergent-insoluble, acid detergent-soluble protein, and C, acid detergent-insoluble protein.

Table 2. Growth performance, nutrient intake, and digestibility in lambs fed on ryegrass hay or ryegrass silage cut at 21 and 35 d.

	Hay		Silage			P-value
	H21	H35	S21	S35	SEM	Method	Cut	M × C
LW intake (kg)	21.9	23.0	22. 6	22.2	1.26	0.120	0.100	0.100
ADG (g/d)	132^ab	108^b	171^a	118^ab	10.0	0.110	0.009	0.008
MP intake (g/kg LW^0.75/d)	8.51^ab	7.15^b	10.0^a	7.67^ab	0.07	0.150	0.010	0.470
ME intake (kJ/kg LW^0.75/d)	1118^ab	983^b	1267^a	1035^ab	69.0	0.150	0.010	0.480
Feed coversion	8.2	8.4	5.1	6.8	0.87	0.008	0.100	0.110
DM intake (g/kg LW^0.75)
Forage	66.9	55.2	60.0	52.8	3.32	0.120	0.008	0.100
Total diet	89.5	77.8	82.6	75.4	3.34	0.120	0.009	0.110
DM Digestibility (g/kg DM)	614^ab	558^b	685^a	638^ab	21.1	0.008	0.043	0.046
OM intake (g/kg LW^0.75)
Forage	55.2	44.3	51.0	44.1	2.75	0.110	0.009	0.120
Total diet	82.8	70.9	77.4	70.2	4.01	0.110	0.047	0.100
OM digestibility (g/kg DM)	651^bc	596^c	732^a	699^ab	19.1	0.001	0.890	0.008
NDF intake (g/kg LW^0.75)
Forage	34.0^a	31.7^a	30.6^ab	26.9^b	1.81	0.001	0.110	0.100
Total diet	37.1^a	35.1^a	34.1^ab	30.2^b	1.80	0.001	0.110	0.130
NDF digestibility (g/kg DM)	672	657	652	614	24.4	0.120	0.108	0.109

^abcDifferent letters in the same row indicate a significant difference (P < 0.05).

SEM = Standard error mean; M = Method (silage vs. Hay), C = age at cut (21 or 35 days), M × D = interaction of the method with age. ADG = Average daily gain; FC = feed conversion (daily intake/ADG), ME intake = metabolisable energy intake and MP intake = metabolisable protein intake were calculated according to equations of Luo et al. (2004a).

LW: live-weight; NDF: Neutral detergent fibre.

Table 3. Nitrogen (N) balance (g/day) and concentration of purine derivatives (mmol/day) in urine in lambs fed on ryegrass hay or ryegrass silage cut at 21 and 35 d.

	Hay		Silage			P-value
	H21	H35	S21	S35	SEM	Method	Cut	M × C
N intake	27.6	25.9	28.2	24.9	1.45	0.110	0.100	0.120
N excretion
N faeces	9.3^a	9.1^a	6.7^b	6.6^b	0.40	0.009	0.110	0.008
N urine	7.2^b	9.8^ab	12.9^a	8.3^b	1.12	0.001	0.100	0.040
Balance	11.1	7.0	8.6	9.9	1.21	0.130	0.100	0.100
Allantoin	4.46^b	2.92^d	7.02^a	3.46^c	0.62	0.001	0.001	0.001
Uric acid	0.53^b	0.43^c	0.70^a	0.49^c	0.07	0.036	0.120	0.110
Total purine derivatives	5.01^b	3.03^d	7.91^a	3.95^c	0.67	0.001	0.001	0.001

^abcdDifferent letters in the same row indicate a significant difference (P < .05).

SEM = Standard error mean; M = method (Silage vs. Hay); C = age at cut (21 or 35 days); M × D = interaction of the method with age.

Table 4. In vitro gas production (mL gas/g DM) of ryegrass hay (H) and ryegrass silage (S) at two maturity stages (21 or 35 days).

	Hay		Silage			P-value
	H21	H35	S21	S35	SEM	Method	Cut	Method × Cut
b	179^d	130^e	167^d	166^d	9.19	0.12	0.04	0.03
c	0.035	0.028	0.039	0.038	0.002	0.10	0.11	0.10
Lag time	0.82	1.74	0.62	1.54	0.235	0.11	0.13	0.11
Gas 24 h	102.1	58.4	100	97.2	7.83	0.13	0.07	0.11
Gas 48 h	147.6^d	96.2^e	139^d	135^de	6.70	0.13	0.02	0.04
Gas 96 h	173^d	119^e	164^d	162^d	5.85	0.08	0.01	0.01
IVDMD	62.9^d	52.4^e	67.2^d	65.0^d	0.72	0.01	0.01	0.01
OMd	47.2^d	41.3^e	54.4^d	50.3^d	2.33	0.02	0.04	0.03
GY24	162	112	149	149	13.2	0.53	0.21	0.21
SCFA	0.449	0.255	0.442	0.427	0.03	0.13	0.07	0.12
MCP	584^d	498^e	628^d	607^d	9.51	0.01	0.01	0.04
RGP	276	228	244	249	10.5	0.71	0.19	0.11

^deDifferent letters in the same row indicate a significant difference (P < .05).

SEM = Standard error mean, IVDMD = Dry matter disappearance (mg/100 mg), OMd = Organic matter disappearance (mg/100 mg), RGP = Relative gas production (ml gas/g IVDMD96h); GY24 = gas yield at 24 h (ml gas/g IVDMD); SCFA = short chain fatty acids (mmol/g DM); MP = microbial protein production (mg/g DM); M = method (silage vs. hay), Cut = age at cut (21 or 35 days).

Data availability statement

Data and materials that support the results and analyses presented in this study are freely available upon request.