Nutritional evaluation of wet brewers’ grains as substitute for common vetch in ensiled total mixed ration

Figures & data

Table 1. Chemical compositions of ingredients used in total mixed ration.

Items^a	Wet brewers’ grains	Common vetch	Oat	Hulless barley straw	Mixed concentrate^b
Dry matter (g kg^−1 FW)	241	281	503	969	909
Crude protein (g kg^−1 DM)	286	185	86.5	42.1	154
aNDFom (g kg^−1 DM)	537	523	440	660	280
ADFom (g kg^−1 DM)	280	129	249	189	151
Ether extract (g kg^−1 DM)	71.4	63.0	76.9	53.9	59.0
Ash (g kg^−1 DM)	36.6	72.2	48.8	63.2	106
Water-soluble carbohydrates (g kg^−1 DM)	65.7	83.8	144	44.8	109
Buffering capacity (mEq kg^−1 DM)	148	336	195	44.0	171
Non-fibrous carbohydrate (g kg^−1 DM)	69.8	157	348	181	401

^aFW: fresh weight; DM: dry matter; mEq: milligram equivalent; aNDFom: neutral detergent fibre assayed with a heat stable amylase and expressed exclusive of residual ash; ADFom: acid detergent fibre expressed exclusive of residual ash.

^bMixed concentrate: 7.5% crack corn, 20% rape cake meal, 20% cotton seed, 27.5% distillers dried grains with solubles, 20% wheat bran, 5% vitamin-mineral.

Table 2. Ingredient proportions, chemical and microbial compositions of total mixed ration substrates.

Items^A	Wet brewers’ grain proportions^B				SEM	p Value^C
	Control	10%B	20%B	30%B		T	L	Q
Ingredient composition (%FW)
Wet brewers’ grains	0	10	20	30	–	–	–	–
Common vetch	45	35	25	15	–	–	–	–
Oat	15	15	15	15	–	–	–	–
Hulless barley straw	10	10	10	10	–	–	–	–
Mixed concentrate	30	30	30	30	–	–	–	–
Chemical composition (g kg^-1 DM)
Dry matter (g kg^-1 FW)	571^a	567^ab	563^ab	559^b	1.74	0.052	0.009	0.998
Crude protein	133^d	137^c	141^b	144^a	1.34	<0.001	<0.001	0.841
Water soluble carbohydrates	97.2	96.5	95.8	95.0	0.52	0.527	0.160	0.932
aNDFom	419	419	419	420	2.23	0.999	0.933	0.918
ADFom	165	172	179	181	3.49	0.414	0.116	0.767
Ether Extract	61.4	61.7	62.1	63.0	0.50	0.749	0.315	0.795
Ash	83.9	82.5	81.0	78.1	1.20	0.410	0.115	0.764
Non-fibrous carbohydrate	303	300	297	295	1.69	0.427	0.116	0.976
Buffering capacity (mEq kg^-1 DM)	189^a	180^b	171^c	162^d	3.17	<0.001	<0.001	0.962
TDN (%DM)	71.1	70.6	70.1	70.0	0.24	0.373	0.101	0.758
Microbial populations (log cfu g^-1 FW)
Lactic acid bacteria	4.97	5.03	5.12	5.10	0.14	0.985	0.739	0.899
Aerobic bacteria	6.61	6.56	6.52	6.59	0.08	0.986	0.906	0.751
Yeast	7.13	7.15	7.26	7.24	0.08	0.934	0.586	0.911

^a–dMeans within a row without a common superscript differ (p < .05).

^ADM: dry matter; FW: fresh weight; aNDFom: neutral detergent fibre assayed with a heat stable amylase and expressed exclusive of residual ash; ADFom: acid detergent fibre expressed exclusive of residual ash; mEq: milligram equivalent; TDN: total digestible nutrients; log: decimal logarithm; cfu: colony-forming units.

^BControl: no wet brewers’ grains; 10%B: 10% wet brewers’ grains of FW; 20%B: 20% wet brewers’ grains of FW; 30%B: 30% wet brewers’ grains of FW.

^CT: effect of wet brewers’ grains proportions; L: linear effect of wet brewers’ grains proportions; Q: quadratic effect of wet brewers’ grains proportions; SEM: standard error of the mean.

Table 3. Chemical and microbial composition of ensiled total mixed ration after 70 days of ensiling.

Items^A	Wet brewers’ grain proportions^B								SEM	p Value^C
	Control		10%B		20%B		30%B			T	L	Q
Fermentation characteristics (g kg^-1 DM)
pH	4.65^a	4.44^b		4.35^c		4.32^c		0.04		<0.001	<0.001	0.002
Lactic acid	77.4^b	86.1^a		83.7^a		85.4^a		2.58		0.044	0.502	0.053
Acetic acid	14.7	14.5		13.2		12.4		0.44		0.212	0.051	0.745
Lactic acid/acetic acid	5.25^b	5.94^a		6.37^a		6.86^a		0.22		0.009	0.005	0.104
Propionic acid	3.91^a	2.85^b		3.03^b		3.24^b		0.14		0.010	0.040	0.005
Butyric acid	1.68^a	0.94^b		1.06^b		1.02^b		0.10		<0.001	0.062	0.001
VFAs	20.3^a	18.2^ab		17.6^ab		16.9^b		0.54		0.126	0.030	0.461
Ethanol	8.44^b	8.81^b		10.4^a		13.4^a		0.72		0.024	0.005	0.213
Water soluble carbohydrates	24.5^d	34.8^c		42.5^b		48.1^a		2.73		<0.001	<0.001	0.096
NH3-N (g kg^-1 TN)	97.2^a	86.3^b		78.9^c		76.0^c		2.76		0.003	0.001	0.202
Chemical compositions (g kg^-1 DM)
Dry matter (g kg^-1 FW)	558	550		550		538		3.29		0.191	0.052	0.740
DM recovery (g kg^-1 FW)	912^b	924^a		927^a		931^a		2.39		0.003	0.001	0.118
Crude protein	135	144		146		147		2.72		0.444	0.160	0.501
Ash	87.3	69.7		81.7		75.1		3.06		0.194	0.342	0.342
Ether extract	77.8^b	74.1^b		79.6^b		87.6^a		1.68		<0.001	<0.001	<0.001
aNDFom	545	584		562		552		6.17		0.526	0.985	0.230
ADFom	187	188		178		195		7.18		0.904	0.856	0.643
Non-fibrous carbohydrate	155	131		131		139		7.52		0.857	0.651	0.497
TDN (%DM)	69.6	69.5		70.2		69.0		0.50		0.901	0.839	0.652
Microbial populations (log cfu g^-1 FW)
Lactic acid bacteria	7.79	7.59		7.62		7.70		0.07		0.779	0.739	0.372
Aerobic bacteria	6.95	5.96		6.55		6.31		0.17		0.203	0.346	0.244
Yeast	6.12	5.89		5.90		5.95		0.05		0.255	0.227	0.124

^a–dMeans within a row without a common superscript differ (p < .05).

^ADM: dry matter; FW: fresh weight; VFAs: volatile fatty acids; NH₃-N: ammonia nitrogen; TN: total nitrogen; aNDFom: neutral detergent fibre assayed with a heat stable amylase and expressed exclusive of residual ash; ADFom: acid detergent fibre expressed exclusive of residual ash; mEq: milligram equivalent; TDN: total digestible nutrients; log: decimal logarithm; cfu: colony-forming units.

^BControl: no wet brewers’ grains; 10%B: 10% wet brewers’ grains of FW; 20%B: 20% wet brewers’ grains of FW; 30%B: 30% wet brewers’ grains of FW.

^CT: effect of wet brewers’ grains proportions; L: linear effect of wet brewers’ grains proportions; Q: quadratic effect of wet brewers’ grains proportions; SEM: standard error of the mean.

Table 4. Chemical compositions of four ensiled total mixed ration (ETMR) after exposure to air.

Items^1	Days after unloading	Wet brewers’ grain proportions^2				Day mean	SEM	p Value^3			p Value for contrasts^4
		Control	10%B	20%B	30%B			T	D	T × D	L	Q
pH	0	4.65	4.44	4.35	4.32	4.44	0.01	<0.001	0.008	0.445	<0.001	<0.001
	6	4.71	4.44	4.41	4.37	4.48
	9	4.72	4.48	4.40	4.38	4.50
	14	4.69	4.54	4.46	4.36	4.51
	ETMR mean	4.69^A	4.48^B	4.41^C	4.36^D
Lactic acid (g kg^-1 DM)	0	77.4	96.1	83.7	85.4	85.7	1.58	<0.001	0.026	0.062	0.007	0.002
	6	74.3	104	103	98.9	94.9
	9	76.1	118	103	96.4	98.4
	14	81.7	97.4	72.0	101	87.9
	ETMR mean	77.4^C	104^A	90.4^B	95.3^AB
Water soluble carbohydrates (g kg^-1 DM)	0	24.5	34.8	42.5	48.1	37.5^a	0.61	0.011	<0.001	<0.001	0.008	0.034
	6	22.0	18.4	20.9	23.4	21.2^b
	9	20.5	15.1	15.6	14.6	16.5^b
	14	24.1	18.5	13.4	23.8	19.9^b
	ETMR mean	22.8	21.7	23.1	27.5
NH3-N (g kg^-1 TN)	0	97.2	86.3	78.9	76.0	84.6	1.77	0.024	0.683	0.592	0.005	0.194
	6	82.6	82.3	81.3	70.3	79.1
	9	88.7	80.6	83.8	83.3	84.1
	14	99.5	78.9	68.3	80.5	81.8
	ETMR mean	92.0^A	82.0^B	78.1^B	77.5^B
Ethanol (g kg^-1 DM)	0	8.44	8.82	10.4	13.4	10.3^a	0.15	<0.001	<0.001	0.031	<0.001	0.365
	6	0.87	0.76	2.67	3.28	1.89^b
	9	0.21	2.35	1.80	2.48	1.71^b
	14	0.33	0.86	0.63	1.54	0.84^b
	ETMR mean	2.46	3.20	3.88	5.17
VFAs (g kg^-1 DM)	0	20.3	18.2	17.6	16.9	18.3^ab	0.36	0.015	0.053	0.263	0.113	0.007
	6	19.5	17.9	19.1	18.4	18.7^ab
	9	21.3	18.2	19.3	18.5	19.3^a
	14	19.8	13.3	13.6	19.3	16.5^b
	ETMR mean	20.2^A	16.9^B	17.4^B	18.3^AB

^A-CMeans within a row without a common superscript differ (p < .05); ^a-bMeans within a line without a common superscript differ (p < .05).

¹ETMR: ensiled total mixed ration; DM: dry matter; VFAs: volatile fatty acids; NH₃-N: ammonia nitrogen; TN: total nitrogen.

²Control: no wet brewers’ grains; 10%B: 10% wet brewers’ grains of FW; 20%B: 20% wet brewers’ grains of FW; 30%B: 30% wet brewers’ grains of FW.

³T: effect of wet brewers’ grains proportions; D: effect of exposure days; T x D: effect of interaction between WBG proportions and exposure days; SEM: standard error of the mean.

⁴L: linear effect of wet brewers’ grains proportions; Q: quadratic effect of wet brewers’ grains proportions.

Table 5. Microbial compositions of four ensiled total mixed ration (ETMR) after exposure to air.

Items^1	Days after unloading	Wet brewers’ grain proportions^2				Day mean	SEM	p Value^3			p Value for contrasts^4
		Control	10%B	20%B	30%B			T	D	T × D	L	Q
Lactic acid bacteria (log cfu g^-1 FW)	0	7.79	7.59	7.62	7.70	7.68^b	0.04	0.079	<0.001	0.015	0.021	0.390
	6	7.48	7.09	6.92	6.71	7.05^c
	9	7.26	7.57	7.46	7.62	7.48^b
	14	8.12	8.07	8.35	7.39	7.98^a
	ETMR mean	7.66	7.58	7.59	7.36
Aerobic bacteria (log cfu g^-1 FW)	0	6.95	5.96	6.55	6.31	6.44	0.08	0.013	0.059	0.015	0.006		0.053
	6	6.71	7.00	6.38	6.03	6.53
	9	5.62	6.78	5.74	5.85	6.00
	14	6.79	6.62	7.09	5.46	6.49
	ETMR mean	6.52^A	6.59^A	6.44^A	5.91^B
Yeasts (log cfu g^-1 FW)	0	6.12	5.89	5.90	5.95	5.97^a	0.06	0.013	0.005	0.135	0.142		0.012
	6	5.77	6.29	5.84	5.90	5.95^a
	9	4.83	6.06	5.44	5.60	5.48^b
	14	4.75	5.70	5.90	5.43	5.45^b
	ETMR mean	5.37^B	5.99^A	5.77^AB	5.72^AB

^A-BMeans within a row without a common superscript differ (p < .05); ^a-cMeans within a line without a common superscript differ (p < .05).

¹ETMR: ensiled total mixed ration; FW: fresh weight; log: decimal logarithm; cfu: colony-forming units.

²Control: no wet brewers’ grains; 10%B: 10% wet brewers’ grains of FW; 20%B: 20% wet brewers’ grains of FW; 30%B: 30% wet brewers’ grains of FW.

³T: effect of wet brewers’ grains proportions; D: effect of exposure days; T × D: effect of interaction between WBG proportions and exposure days; SEM: standard error of the mean.

⁴L: linear effect of wet brewers’ grains proportions; Q: quadratic effect of wet brewers’ grains proportions.

Figure 1. Changes of temperature of ensiled total mixed ration during aerobic exposure. Control, no wet brewers’ grains (WBG); 10%B, 10% WBG of fresh weight (FW); 20%B, 20% WBG of FW; 30%B, 30% WBG of FW. AT, ambient temperature; AT + 2, ambient temperature plus 2 °C.

Table 6. In vitro gas production kinetics and digestibility, and available energy of ensiled total mixed ration after 70 days of ensiling.

Items^A	Wet brewers’ grain proportions^B				SEM	p Value^C
	Control	10%B	20%B	30%B		T	L	Q
In vitro digestibility
IVDMD (%)	61.1	58.6	60.3	56.2	0.90	0.241	0.119	0.620
IVNDFD (%)	54.3	52.8	54.5	50.4	0.86	0.335	0.217	0.437
OMD (%)	77.7^a	74.9^ab	74.3^ab	72.4^b	0.68	0.015	0.003	0.653
SCFA (mmol g^–1 DM)	7.37^a	7.04^ab	6.95^ab	6.71^b	0.08	0.015	0.003	0.661
MCP (mg g^-1 DM):	464	447	465	428	8.70	0.438	0.281	0.600
Available energy
ME (MJ kg^−1 DM)	11.3^a	10.9^ab	10.8^ab	10.5^b	0.10	0.016	0.003	0.656
NEL (MJ kg^−1 DM)	6.99^a	6.70^ab	6.63^ab	6.43^b	0.07	0.016	0.003	0.648
Gas production kinetics
GP72 (mL)	99.4^a	93.3^ab	94.2^ab	91.7^b	1.11	0.045	0.015	0.298
Potential gas production (mL)	116	84.2	96.1	90.0	5.62	0.235	0.210	0.237
Gas production rate constant (mL h^−1)	0.049^a	0.048^ab	0.037^ab	0.030^b	0.003	0.036	0.007	0.474
Half time (h)	2.97^a	2.74^ab	2.90^ab	2.64^b	0.05	0.037	0.029	0.871
AGPR (mL h^-1)	20.2^a	14.5^ab	12.9^ab	9.40^b	1.33	0.004	0.001	0.365

^a–bMeans within a row without a common superscript differ (p < .05).

^A DM: dry matter; FW: fresh weight; IVDMD: in vitro dry matter digestibility; IVNDFD: in vitro NDF degradability; OMD: organic matter digestibility; SCFA: short chain fatty acid; MCP: microbial crude protein; ME: metabolisable energy; NE_L: net energy for lactation; AGPR: the average gas production rate.

^B Control: no wet brewers’ grains; 10%B: 10% wet brewers’ grains of FW; 20%B: 20% wet brewers’ grains of FW; 30%B: 30% wet brewers’ grains of FW.

^C T: effect of wet brewers’ grains proportions; L: linear effect of wet brewers’ grains proportions; Q: quadratic effect of wet brewers’ grains proportions; SEM: standard error of the mean.