Methane emissions from sheep fed fermented or non-fermented total mixed ration containing whole-crop rice and rice bran

Animal Feed Science and Technology 157 (2010) 72–78

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Methane emissions from sheep fed fermented or non-fermented total mixed ration containing whole-crop rice and rice bran Yang Cao a,1 , Toshiyoshi Takahashi a,∗ , Ken-ich Horiguchi a , Norio Yoshida a , Yimin Cai b a b

Faculty of Agriculture, Yamagata University, Tsuruoka 1-23, Yamagata 997-8555, Japan Functional Feed Research Team, National Institute of Livestock and Grassland Science, Nasushiobara 768, Tochigi 329-2793, Japan

a r t i c l e

i n f o

Article history: Received 16 April 2009 Received in revised form 10 January 2010 Accepted 11 February 2010 Keywords: Digestibility Fermented total mixed ration Methane Ruminal fermentation Sheep Whole-crop rice

a b s t r a c t The effects of ensiling a total mixed ration (TMR) were compared to those of a control TMR whole-crop rice (WCR) ensiled separately and mixed with other ingredients before feeding. Nutritive value, nitrogen balance, ruminal fermentation and the methane production of sheep were evaluated. Four Suffolk sheep (49.5 ± 3.2 kg) were used in a 2 (treatment) × 2 (period) cross-over design experiment. Experimental treatments were control (not fermented) TMR and fermented TMR (FTMR). Each TMR contained WCR, a compound feed, a vitamin–mineral supplement, dried beet pulp and rice bran in a ratio of 300:250:15:135:300, respectively, on a dry matter basis. The lactic acid contents of the control TMR and FTMR were 5.5 and 73.4 g/kg, respectively. Apparent digestibility of crude protein, ether extract, acid detergent fibre and gross energy was higher for FTMR, which also had higher digestible crude protein and digestible energy concentrations than the control TMR. There were no differences in ruminal pH by TMR type before feeding or 4 h after feeding, although pH was higher (P=0.0039) in FTMR 2 h after feeding. Total volatile fatty acid and NH3 -N was higher and butyric acid was lower for FTMR 2 and 4 h after feeding, whereas propionic acid was higher only 2 h after feeding. FTMR decreased (P=0.0001) daily methane emissions and energy lost as methane production. These results show that FTMR increases digestibility and decreases ruminal methane emissions and energy loss compared to non-fermented TMR, and that the depression effect of FTMR on methane emission can contribute to the conversion of lactic acid to propionic acid in the rumen. © 2010 Elsevier B.V. All rights reserved.

1. Introduction Methane is an important greenhouse gas, and its release into the atmosphere is directly linked with animal agriculture, particularly ruminant production. The methane from the world population of ruminants contributes approximately 0.15 of the total atmospheric methane flux (Sahoo et al., 2000). Methane is produced as a result of the microbial fermentation of feed within the rumen, and production represents a loss in productive energy for an animal amounting to up to nearly 0.12 of total

Abbreviations: ADFom, acid detergent fibre expressed exclusive of residual ash; aNDFom, neutral detergent fibre assayed with a heat-stable amylase and expressed exclusive of residual ash; A/P ratio, acetate–propionate ratio; BW, body weight; CP, crude protein; DM, dry matter; EE, ether extract; FTMR, fermented total mixed ration; GE, gross energy; NFC, non-fibrous carbohydrate; OM, organic matter; RB, rice bran; TMR, total mixed ration; VFA, volatile fatty acid; WCR, whole-crop rice. ∗ Corresponding author. Present address: Faculty of Agriculture, Yamagata University, Tsuruoka 1-23, Yamagata 997-8555, Japan. Tel.: +81 0235 28 2827; fax: +81 0235 28 2827. E-mail address: [email protected] (T. Takahashi). 1 Present address: Functional Feed Research Team, National Institute of Livestock and Grassland Science, Nasushiobara 768, Tochigi 329-2793, Japan. 0377-8401/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.anifeedsci.2010.02.004

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Table 1 Chemical composition of concentrate feedstuffs and total mixed ration. WCR

Concentratea

VMSb

Beet pulp

Rice bran

Treatment Controlc

Nutrient composition Dry matter (DM; g/kg) Organic matter (g/kg DM) Crude protein (g/kg DM) Ether extract (g/kg DM) Non-fibrous carbohydrate (g/kg DM) Ash (g/kg DM) Acid detergent fibre (g/kg DM) Neutral detergent fibre (g/kg DM) Gross energy (MJ/kg DM) Fermentation profile pH Lactic acid (g/kg DM) Acetic acid (g/kg DM) Propionic acid (g/kg DM) Butyric acid (g/kg DM) NH3 -N (g/kg TNe ) Frieg’s mark V-score

FTMRd

456 879 102 26 161 121 343 590 181

899 916 206 32 305 84 168 373 189

910 886 217 31 232 114 157 406 184

907 949 84 70 337 51 256 521 185

903 876 168 242 174 124 103 291 225

687.6 908.0 145.7 73.6 263.6 92.0 209.9 425.1 19.5

± ± ± ± ± ± ± ± ±

0.31 0.35 0.47 0.24 2.25 0.35 1.64 1.32 0.26

444.7 897.6 150.1 94.2 192.7 102.4 217.1 460.6 19.8

± ± ± ± ± ± ± ± ±

0.85 0.17 0.28 0.23 3.35 0.17 0.86 1.46 0.11

– – – – – – – –

– – – – – – – –

– – – – – – – –

– – – – – – – –

– – – – – – – –

5.24 5.5 4.6 0.1 0.3 26.3

± ± ± ± ± ±

0.2 1.5 1.5 0.04 0.02 3.1 – –

3.97 73.4 9.9 0.1 0.3 54.3 100 96.2

± ± ± ± ± ± ± ±

0.1 4.6 2.3 0.02 0.02 3.7 0.0 1.8

a

Formula feed (“Koushi Ikusei Special Mash” made with 120 g/kg CP in fresh matter; Zenno, Tokyo, Japan). Commercial vitamin–mineral supplement product (vitamin A, 5,000,000 IU/kg; vitamin D3, 1,000,000 IU/kg; vitamin E, 2 g/kg; vitamin K3, 0.2 g/kg; vitamin B1, 0.5 g/kg; vitamin B2, 1 g/kg; vitamin B6, 0.1 g/kg; vitamin B12, 0.001 g/kg; nicotinic acid, 6 g/kg; choline chloride, 2 g/kg; calcium pantothenateD, 10 g/kg; Mn, 0.16 g/kg; Zn, 0.7 g/kg; Fe, 0.55 g/kg; Cu, 0.14 g/kg; I, 0.33 g/kg; Co, 0.04 g/kg; methionine, 1 g/kg; lidocaine hydrochloride, 0.5 g/kg; Snow Brand Seed, Iwate, Japan). c Non-fermented total mixed ration. d Fermented total mixed ration. e Total nitrogen. b

energy intake (Giger-Reverdin and Sauvant, 2000; Johnson et al., 2000). Diet composition and level of feed intake can have a major effect on methane production (Benchaar et al., 2001). Highly concentrated diets should reduce methane production (Fahey and Berger, 1988). Johnson and Johnson (1995) reported a methane energy loss of 0.06–0.07 gross energy intake when foragers were fed at the level of nutritional maintenance. Many studies have investigated how to inhibit methane production by ruminants to help address global climate change (Van Nevel and Demeyer, 1995; Kung et al., 1998; McGinn et al., 2004; Beauchemin and McGinn, 2006). The ideal methane inhibitor must be extremely specific, persistent, and long lasting; must not harm the animal; and must not leave behind residue in edible products (Van Nevel and Demeyer, 1996). The inhibition of methane production is normally accompanied by an increase in propionate production (Wolin, 1975), which uses hydrogen and lactic acid (Moss et al., 2000). Understanding the variability in enteric methane production related to diet is essential to decreasing uncertainty in greenhouse gas emission inventories and to identifying viable greenhouse gas reduction strategies. To date, the effect of a fermented total mixed ration (FTMR) on methane production in the rumen has not been investigated in vivo, although FTMR does lead to low methane production in vitro (Cao et al., 2009). The objectives of this experiment were to evaluate the effects of FTMR on digestibility, ruminal fermentation characteristics, methane emissions and energy loss in sheep. In particular, the study tested the hypothesis that FTMR (which is high in lactic acid) depresses methane emissions by converting lactic acid to propionic acid in the rumen. 2. Materials and methods Animal experiments were approved by the Committee of Animal Experimentation and were performed under the institutional guidelines for animal experiments of the Faculty of Agriculture, Yamagata University, Japan. 2.1. Preparation of whole-crop rice (WCR) silage and total mixed ration (TMR) WCR (Haenuki) was cultivated using conventional methods in a paddy field on an experimental farm at Yamagata University, harvested when fully ripe and cut to a length of 2 cm. TMR was prepared using compound feed (Kitanihon-kumiai Feed, Yamagata, Japan; Table 1), WCR, dried beet pulp (Zenno, Tokyo, Japan), a vitamin–mineral supplement (Snow Brand Seed, Iwate, Japan) and rice bran (RB; Yamagata University Farm, Yamagata, Japan). Experimental treatments were non-fermented TMR as control and FTMR ensiled in a silo for silage fermentation. The proportions of WCR, RB, feed concentrate, dried beet pulp and vitamin–mineral supplement were fixed at 300, 300, 250, 135 and 15 g/kg TMR dry matter (DM), respectively. FTMR was prepared as follows: WCR, RB, feed concentrate, dried beet pulp and vitamin–mineral supplement were mixed and added to lactic acid bacteria (Lactobacillus plantarum Chikuso-1; 5 mg/kg fresh TMR; Snow Brand Seed, Sapporo, Japan). This mix was then adjusted with water to a moisture

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content of 550 g/kg, and 100 kg was ensiled in a drum can silo 200 L in volume (Minikon-silo; KD-Service, Tokyo, Japan). Fresh TMR was produced by separating WCR from the other ingredients, ensiling it in a drum can silo alone and mixing it with other ingredients before feeding. Samples were stored outdoors (9–32 ◦ C) for 60 days, and identical proportions were fed to animals.

2.2. Feeding of animals and experimental design Four Suffolk sheep (49.5 ± 3.2 kg) were randomly divided into two groups (each with two sheep) and used in a 2 (treatment) × 2 (period) cross-over design experiment. Group 1 received the FTMR and group 2 received control TMR in period 1; group 1 received the control TMR and group 2 received FTMR in period 2. The sheep were individually housed in metabolic cages and fed diets at 20 g/kg body weight (BW) on a DM basis once daily at 09:00. The metabolisable energy maintenance level was set according to Nutrient Requirements of Sheep (NRC, 1985). Water was accessible at all times. A 14-day preliminary adjustment period was followed by a 5-day period during which all faeces and urine were collected to evaluate apparent digestibility and nitrogen balance. Ruminal fluid was sampled immediately before the morning feeding and at 2 and 4 h after feeding on day 19 of each period. Ruminal fluid pH was measured immediately, and samples were separated from feed articles through two layers of gauze. Samples were frozen (−20 ◦ C) for later analysis of volatile fatty acid (VFA) and NH3 -N.

2.3. Methane emission from expiratory gas Emission methane experiments were carried out on all sheep after each treatment and period. A 5-day total faeces and urine collection period was followed by a 2-day period (excluding the calibration time required for analysers) during which air was collected for a period of 24 h (from the 09:00 feeding to the next day’s 09:00 feeding). Expiratory gas was collected using a head hood-type respiration chamber (85 cm wide × 45 cm deep × 90 cm tall; Nishida et al., 2007), dehydration device, gas pump (85–95 L/min; JP-80 vacuum pump; Tokyo Deodorant, Tokyo, Japan), gas flow meter (N6 LPG; Aichi Tokei Denki, Nagoya, Japan), sampling bag (60 L) and vinyl hose (I.D., 20 mm). The chamber had a hinged door through which feed and water were provided, and a fan was installed to circulate air throughout the respiration chamber. Each end was fitted with additional individual chambers for dehydration; chambers were connected to the device by a hose. The dehydration device, which was connected to a gas pump by a hose, filtered moisture from the chamber air, and the gas pump moved the air from the chamber into a gas flow meter (via a hose) and at the same time helped provide fresh air into the chamber. The gas flow meter measured the total volume of air leaving the chamber for 24 h and was connected to a sampling bag by a hose fitted with a control valve so that the collected air sample was less than 60 L for 24 h. Four sampling bags of expiratory gas were collected and analysed for methane content.

2.4. Chemical analysis The FTMR and faeces were dried in a forced draft oven at 60 ◦ C for 48 h and ground on a sample mill (Foss Tecator; Akutalstuku, Tokyo, Japan) to pass through a 2-mm screen. DM, crude protein (CP), ether extract (EE) and ash were analysed according to methods 934.01, 976.05, 920.39 and 942.05, respectively, of the Association of Official Analytical Chemists (AOAC, 1990). Neutral detergent fibre (aNDFom) and acid detergent fibre (ADFom) were analysed according to Van Soest et al. (1991). Heat-stable amylase and sodium sulphite were used in the NDF procedure, and the results were expressed without residual ash. Non-fibrous carbohydrate (NFC) was calculated as follows: NFC = 100 − CP − NDF − EE − ash (NRC, 2001). Gross energy (GE) was determined using an automatic bomb calorimeter (OSK 150; Ogawa Sampling, Tokyo, Japan). Urinary N was determined using the Kjeldahl procedure described by the AOAC (1990). The fermentation products of the FTMR were determined using cold-water extracts. Wet FTMR (50 g) was homogenised with 200 mL sterilised distilled water and stored at 4 ◦ C overnight (Cai et al., 1999). The pH was measured using a glass electrode pH meter (Horiba D-21; Horiba, Kyoto, Japan). Lactic acid and NH3 -N were analysed according to Takahashi et al. (2005). The VFA was steam-distilled and measured qualitatively and quantitatively using a gas chromatographer (G-5000A; Hitachi, Tokyo, Japan) equipped with a thermal conductivity detector and a G-5000 stainless column (3 mm × 2 m; Unisole F-200; GL Science, Tokyo, Japan). The analytical conditions were as follows: column oven temperature, 140 ◦ C; injector temperature, 210 ◦ C; detector temperature, 250 ◦ C. To assess FTMR quality, we calculated Frieg’s marks (an evaluation method that relies on the ratio of the organic acid composition) and V-scores (an evaluation method that relies on the distribution point calculated from acetic acid, butyric acid and NH3 -N; Takahashi et al., 2005). The pH, VFA and NH3 -N concentrations in ruminal fluid samples were measured using the same methods as for the FTMR filtrates. Gas samples were analysed (Horiguchi and Takahashi, 2001) for methane using a gas chromatographer (G-5000A; Hitachi). The analytical conditions were as follows: G-5000 stainless column (molecular sieves 60–80, 3 mm × 2 m; Nishio, Tokyo, Japan); column oven temperature, 80 ◦ C; injector temperature, 100 ◦ C; detector temperature, 110 ◦ C.

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Table 2 Nutrient digestibility, nutrient content and nitrogen balance in the total mixed ration fed to wethers. Item

Treatment Control

Apparent digestibility Dry matter Organic matter Crude protein Ether extract Non-fibrous carbohydrate Acid detergent fibre Neutral detergent fibre Gross energy

0.656 0.711 0.648 0.789 0.925 0.491 0.586 0.709

Nutrient content Digestible crude protein (g/kg DM) Digestible energy (MJ/kg DM)

94.0 13.8

Nitrogen balance (g/day) Nitrogen intake Faecal excretion of nitrogen Urinary excretion of nitrogen Nitrogen retention Allantoin

23.34 8.21 9.76 5.38 1.69

a

SEM

P-value

0.0094 0.0084 0.0075 0.0114 0.0086 0.0186 0.0110 0.0083

0.0518 0.0650 0.0023 0.0282 0.4268 0.0741 0.0043 0.0334

1.00 0.01

0.0004 0.0133

0.81 0.20 0.45 0.47 0.17

0.6105 0.0081 0.0185 0.6823 0.7527

a

FTMR

0.689 0.738 0.704 0.840 0.913 0.549 0.655 0.742 105.0 14.6 23.98 7.08 11.81 5.09 1.61

Fermented total mixed ration.

2.5. Calculations and statistical analysis Energy lost as methane was calculated as the total methane produced in litres per day at standard temperature and pressure × 9.45 × 4.184 kJ/L (Brouwer, 1965). Digestion, ruminal VFA, and methane emission data were analysed using PROC MIXED (SAS, 2003) appropriate for a 2 × 2 cross-over design experiment. The model had fixed effects for diet, period and sequence group and animal within sequence group as random variables. Differences amongst means were considered statistically significant at P<0.05, and differences at 0.05
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Table 3 pH volatile fatty acid (VFA) and ammonia-N of rumen fluid of sheep fed total mixed ration. Hours after feeding

Treatment Control

pH

0 2 4

Total VFA (mM)

0 2 4

55.5 88.4 87.4

Acetic acid (mmol/mol)

0 2 4

Propionic acid (mmol/mol)

P-value

FTMR

0.09 0.06 0.11

0.5760 0.0039 0.1751

59.2 127.2 116.2

3.2 7.9 7.4

0.4675 0.0134 0.0386

478.7 531.7 516.3

506.8 546.1 550.9

8.3 24.6 11.0

0.0761 0.6944 0.0714

0 2 4

337.9 370.5 380.2

316.4 392.4 383.3

19.8 5.4 12.1

0.5045 0.0296 0.8621

Isobutyric acid (mmol/mol)

0 2 4

34.6 4.3 4.3

27.7 4.1 4.9

10.5 0.7 1.0

0.6548 0.9035 0.7111

Butyric acid (mmol/mol)

0 2 4

144.0 138.9 151.2

144.2 86.6 97.5

9.4 7.3 12.4

0.9863 0.0042 0.0255

Isovaleric acid (mmol/mol)

0 2 4

54.9 13.1 9.4

51.1 28.9 21.5

3.7 7.0 4.9

0.5237 0.1626 0.1511

Valeric acid (mmol/mol)

0 2 4

13.8 11.5 10.5

13.7 16.1 14.3

1.0 3.5 1.2

0.9324 0.4248 0.0755

A/Pb

0 2 4

0.11 0.12 0.05

0.2363 0.6828 0.3028

NH3 -N (mg/L)

0 2 4

a b

7.28 6.71 6.64

SEM a

1.43 1.47 1.36 56.4 87.7 59.3

7.20 6.33 6.40

1.64 1.40 1.44 50.9 183.3 162.0

4.2 15.8 16.8

0.4000 0.0055 0.0071

Fermented total mixed ration. Acetic acid/propionic acid ratio.

before feeding, it was lower in FTMR 2 and 4 h after feeding (P=0.0042 and P=0.0255, respectively). Isovaleric acid, valeric acid and the acetate–propionate ratio (A/P ratio) were not affected by dietary TMR. NH3 -N concentration did not differ between the two TMR types before feeding, but it was higher in FTMR 2 and 4 h after feeding. 3.5. Energy intake and methane emission There was no difference in daily GE intake between the two TMR types (Table 4). Compared to the control, FTMR decreased daily methane emission by 10 L per sheep, by 9.84 L per kg DM intake, by 17.26 L per kg digestible DM and by 0.54 L per kg metabolic BW. FTMR also decreased the amount of daily energy lost as methane by 396 kJ per sheep, by 21.3 kJ per kg metabolic BW and by 20.9 J per kJ GE intake. 4. Discussion The main losses in low-DM silages are associated with the fermentation process and effluent loss (Hameleers et al., 1999). In the present experiment, DM content was lower in FTMR than in the control because moisture was higher in the FTMR. The addition of lactic acid bacteria may have contributed to low pH, high lactic acid content and high Frieg’s marks and V-scores, indicating that the FTMR was of good quality. This is consistent with a previous study (Shioya, 2008) showing that FTMR can have low pH, high lactic acid content and low butyric acid levels. As only WCR was ensiled, the control had small amounts of organic acids (i.e., lactic acid, acetic acid, propionic acid and butyric acid) and NH3 -N. Shioya (2008) reported that the DM intake for FTMR was higher than for fresh TMR (i.e., non-fermented TMR). In the present experiment, FTMR had more EE and aNDFom but less NFC than the control; at the same time, there were increases in the apparent digestibility of CP, EE, aNDFom and GE. This is consistent with a recent report that the digestibility of aNDFom increased as aNDFom increased and NFC decreased in TMR made with cassava (Kanjanapruthipong and Buatong, 2004). In

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Table 4 Daily energy intake and methane emission of sheep fed total mixed ration. Treatment

Gross energy (GE) intake kJ kJ/kg of BW0.75 Methane emission L L/kg of DMIb L/kg of DDMc L/kg of BW0.75 Methane energy kJ kJ/kg of BW0.75 J/kJ of GE intake a b c

Control

FTMR

19559.2 1038.1

19810.4 1045.3

39.84 39.87 60.87 2.12 1576.4 83.8 80.8

SEM

P-value

672.3 1.0

0.8058 0.6433

a

29.84 30.03 43.61 1.58 1180.8 62.5 59.9

0.82 1.29 2.10 0.10 32.6 2.3 2.6

0.0001 0.0017 0.0012 0.0007 0.0001 0.0007 0.0013

Fermented total mixed ration. Dry matter intake. Digestible dry matter.

addition, FTMR had more digestible crude protein and digestible energy and led to less faecal excretion of nitrogen but more urinary excretion of nitrogen. There is an inverse relationship between ruminal pH and gas production from fermentation (Waghorn, 1991), and Erfle et al. (1982) found that ruminal pH varied from greater than 5 to less than 7 as VFA production decreased from 80 to 50 mmol/day. In the present experiment, ruminal pH in sheep fed FTMR was always within the normal range, although it was lower for FTMR 2 h after feeding (P=0.0039). FTMR had higher total VFA 2 and 4 h after feeding (P=0.0134 and 0.0386, respectively), which indicates that consuming fermentable carbohydrates leads to a marked postprandial increase in ruminal VFA and decrease in pH. This is in line with reports by Nocek (1997) and Chaucheyras-Durand et al. (2008). Similar to total VFA, the molar concentrations of acetic acid and propionic acid in both the control and FTMR also increased from before feeding to 2 and 4 h after feeding. This might have happened because, after feeding, the NFC, feed concentrate or effective fibre may have been degraded by bacteria into propionic acid, thereby decreasing ruminal pH and the A/P ratio. We suppose that, at the same time, lactic acid from either the FTMR or bacterial fermentation in the rumen might have used hydrogen from the fermentation reaction to further increase the amount of propionic acid. The present study shows that consumption of FTMR instead of non-fermented TMR increases ruminal propionic acid but decreases ruminal butyric acid 2 and 4 h after feeding. Similar to total VFA, NH3 -N concentrations in the control and in FTMR increased 2 h after feeding and tended to decline between 2 and 4 h after feeding. NH3 -N production was higher 2 and 4 h after feeding in FTMR than in the control, possibly because of its higher CP digestibility. In addition, Kanjanapruthipong and Buatong (2004) reported that acetic acid, propionic acid, the A/P ratio and fibre digestibility all increase with an increasing content of non-forage aNDFom from cassava residues. Not only did the FTMR increase digestibility, it also decreased ruminal methane emission. There are two known mechanisms for the conversion of lactic acid or pyruvic acid to propionic acid (Leng, 1970). When lactic acid is secondarily fermented in the rumen by lactate-utilising bacteria such as Megasphaera elsdenii, Selenomonas ruminantium and Veillonella parvula, propionate is generally produced (Dawson et al., 1997; Russell and Wallace, 1997). This can reduce methanogenesis because electrons are used during propionate formation. If hydrogen is then used to convert lactic acid to propionic acid in the rumen (Moss et al., 2000), the hydrogen will decrease, which in turn will inhibit the conversion of hydrogen and CO2 to methane. Russell (1998) reported that over a pH range of 5.3–6.5, methane production is highly correlated with A/P ratio. In the present experiment, ruminal pH ranged from 6.33 to 6.40 after feeding with FTMR, whereas the A/P ratio after feeding decreased compared to before feeding. Although the A/P ratio did not differ between the two treatments, sheep fed FTMR had higher amounts of ruminal propionic acid at 2 h after feeding than those fed the control TMR. Thus, we suspect that the higher lactic acid content of the FTMR diet may have led to the production of propionic acid and, accordingly, lowered methane production; however, without monitoring emissions from the diet itself, it is impossible to make any overall conclusions about the effect of methane emissions on the environment. 5. Conclusions Compared to non-fermented TMR, FTMR increases digestibility, decreases methane emissions and results in a lower loss of energy as methane. The effect of FTMR on reducing methane emissions seems to be a result of the conversion of lactic acid to propionic acid in the rumen.

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