Energy balance and methane production in sheep fed chemically treated wheat straw

Small Ruminant Research 35 (2000) 13±19

Energy balance and methane production in sheep fed chemically treated wheat straw B. Sahoo, M.L. Saraswat*, N. Haque, M.Y. Khan Division of Animal Nutrition, Indian Veterinary Research Institute, Izatnagar, Bareilly 243122, UP, India Accepted 13 May 1999

Abstract Ram lambs of the Muzaffarnagari breed weighing 42 kg were randomly assigned to three groups of ®ve animals. These animals were used to study the effect of chemically treated wheat straw on methane production and energy balance. Wheat straw was treated either with urea (4 kg urea per 100 kg DM) with a storage time of 21 days (treatment I; control) or with urea (1.5 kg per 100 kg DM) without storage time (treatment II) or with urea plus calcium hydroxide (3 kg urea plus 3 kg calcium hydroxide per 100 kg DM) with a storage time of 21 days (treatment III). All straws were fed ad libitum. The crude protein content of wheat straw during feeding was 7.8%, 7.9% and 7.6% in treatments I±III, respectively. Corresponding dry matter (DM) intake was 43.7, 34.9 and 49.5 g kgÿ1 W0.75, respectively which was signi®cantly higher in treatment III than that of treatment II. The DM digestibility in treatments I (54.2%) and III (50.9%) was higher than that of treatment II (42.7%). The digestible energy (DE) intake that was measured in kJ kgÿ1 W0.75 dÿ1 was higher in treatments I (412) and III (471) than that of treatment II (282). Similar trend was observed in metabolizable energy (ME) intake. Methane production per kg digested organic matter (OM) per d was lower in treatments I (301) and III (291) than that of treatment II (461). The energy balance was measured in kJ kgÿ1 W0.75 dÿ1 in treatments I±III, respectively. The energy balance in treatments I (113) and III (170) was higher than that of treatment II (ÿ40). It is concluded that treatment of straw with urea and/or a mixture of urea with calcium hydroxide followed by storage can improve digestibility compared to spraying with urea solution prior to feeding and also reduce methane production per kg digested OM and increase energy balance. # 2000 Elsevier Science B.V. All rights reserved. Keywords: Calcium hydroxide; Energy balance; Methane production; Sheep; Urea; Wheat straw

1. Introduction Methane is an important greenhouse gas second only to carbon dioxide in its contribution to global warming. The world population of ruminants is an important source of methane, contributing approxi*Corresponding author. Tel.: +91-581-442313; fax: +91-581457284.

mately 15% of the total atmospheric methane ¯ux. The control of methane emission is a logical option since atmospheric methane concentration is increasing at a faster rate than carbon dioxide. Per molecule, methane is approximately 30 times more potent as a greenhouse gas than carbon dioxide and it has a relatively short atmospheric lifetime of approximately 10 years compared with over 200 years for carbon dioxide (Moss, 1993). Leng (1991) reported that

0921-4488/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 4 8 8 ( 9 9 ) 0 0 0 5 9 - 0

14

B. Sahoo et al. / Small Ruminant Research 35 (2000) 13±19

methane production from ruminants in the developing countries may be high since the diets are often de®cient in critical nutrients for ef®cient microbial growth in the rumen. Considerable attention has been given to improve feeding value of low quality roughage through physiological, biological and chemical processes (Jackson, 1978). In India, 4% urea level on dry matter (DM) basis is commonly used for urea-ammoniation of wheat straw (Verma, 1983; ICAR, 1985; Rai and Mudgal, 1988). The urea applied is hydrolyzed to ammonia by urease enzyme present in straw. Further improvement by attempting to reduce nitrogen loss due to urea-ammoniation by adding lower level of urea plus calcium hydroxide for treatment has been tried. Calcium hydroxide is potentially cheaper on account of its widespread occurrence in both temperate and tropical countries. Zaman and Owen (1990) reported that organic matter (OM) digestibility of barley straw treated with 3% calcium hydroxide plus 3% urea stored for 56 days was signi®cantly higher than 3% urea. However, data on the effect of wheat straw treated by urea-ammoniation on methane production is not common. A decreasing trend in methane production per kg digested OM (37 vs. 58 l) with a substantial increase in digestible OM content (609 vs. 484 g/kg digestible OM in DM) was observed in sheep fed straw treated on anhydrous ammonia than untreated straw (Moss et al., 1994). The main purpose of this experiment is to determine the effect of chemical treatment of wheat straw with urea or with urea and calcium hydroxide on methane production and energy balance in adult sheep.

excess ammonia and the heat generated to escape. The level of urea in treatment II was measured on the basis of residual nitrogen content of treated straw in treatment I to make the feeds isonitrogeneous. Weighed amount of wheat straw was spread over a tarpaulin sheet and urea solution (30 g urea dissolved in 1 l water for 2 kg wheat straw DM) was sprayed uniformly and mixed manually. It was prepared daily before feeding. In treatment III, 3 kg fertilizer grade urea and 3 kg calcium hydroxide (commercial grade) was dissolved/suspended in 65 l water and the suspension was sprayed on 100 kg wheat straw on DM basis and stacked as that of treatment I and stored for 21 days.

2. Materials and methods

2.3. Methane production and energy balance measurements

2.1. Treatment of wheat straw Wheat straw collected from the local market was a random mixture of different cultivars. In treatment I, chopped wheat straw was treated with fertilizer grade (46.6% nitrogen) urea. Four kg urea was dissolved in 65 l water for 100 kg wheat straw DM. Urea solution was sprayed on the straw and was mixed and stacked manually. Then, it was covered with a large tarpaulin sheet and stored in shade on cemented ¯oor. After 21 days the straw was exposed for 48±72 h to allow

2.2. Feeding of animals and experimental design Adult rams of the Muzaffarnagari breed, 2±3 years old and weighing 42 kg were randomly divided into three groups of ®ve animals each. The animals in group I were given ad lib wheat straw from treatment I, group II from treatment II and group III from treatment III, respectively. Animals were kept in a well ventilated shed with cemented ¯oor having facilities for feeding the animals individually in pens. Animals were dewormed before starting the experiment. Additionally, each animal received 5 g per day of a mineral, trace element and vitamin supplement separately. Feed was offered once at 9.00 h daily after removing the residual feed of the preceding day and water at 10.00 and 15.30 h. After feeding treatment diets for 30 days or more a balance trial was conducted for all animals individually in an open circuit respiration chamber.

Each animal was weighed in the morning before feeding and watering and then shifted to the respiration chamber which was maintained at 258C with a relative humidity of about 65% for adaptation before recording the respiration calorimetry data. Only one animal entered the respiration chamber. A simple type of open-circuit respiration calorimeter for small animals with wooden chamber as described by Bull and Kennett (1973) was constructed in Indian Veterinary Research Institute in 1983 (Khan

B. Sahoo et al. / Small Ruminant Research 35 (2000) 13±19

and Joshi, 1983). A wooden box with internal dimensions 1.5 m0.9 m1.75 m was built. It consisted of a frame of wood having inner wall of plywood and outer wall of hard board. The base of the box was covered on the inner side with a galvanized iron sheet. All the joints were sealed using rubber sheets and synthetic resin adhesive. A hinged door was provided at the front. It was made air tight by ®xing ¯exible rubber strips around the inner edge of the door. Arrangements for closing the door tightly was made with the help of six clamps having nuts and bolts. A 10 mm diameter steel tube with a control valve was provided at the base for the ingoing air. For sampling of the outgoing air a perforated steel tube of 90 cm long with 10 mm diameter was ®xed at the roof of the box. A perspex sheet 5050 cm was provided on one side of the wall to observe the animal and to note the temperature and humidity in the chamber. A manometer and wet and dry bulb thermometer were provided. An iron tube of 5 mm diameter was ®xed into the perspex sheet for connecting the manometer with the inner atmosphere of the chamber. This tube was for passing known quantity of a standard gas for gravimetric calibration. The air from the chamber was removed with the help of a centrifugal exhauster, model 4MS 11/080 (Air Control Installation, Somerset, UK) with a maximum capacity of 170 m3/h. The rate of air ¯ow from the chamber was regulated with the help of a gate valve. A fan was also installed inside the chamber for air circulation. The animal in the chamber was restrained in a metabolism cage for sheep. The cage was further equipped with pulley at the base. The wooden chamber was installed in a room provided with air conditioners. The chamber was always run at a negative pressure to ensure that no air leaked out of it by using the control valve at the inlet. A three-day balance trial was conducted (after 2±3 days of adjustment period) during which total faeces and urine was collected and sampled. During the last two days of the balance trial gas exchange of individual animal was measured for 24 h. Hastings Mass ¯ow meter (Teledyne Hastings ± Raydist, VA, USA) was used to record the ¯ow rate and total volume of air coming out of respiration chamber. Dry and wet bulb temperature were recorded (Decibel Instruments, Chandigarh, India, sl. no. 23/83). Atmospheric pressure was recorded electronically (Appleby and Ireland, sl. no. 252730). Oxygen consumption, carbon

15

dioxide and methane production were determined by measuring the total air ¯ow through the system and the difference in concentration of respective gases between out¯ow and incoming air. Subsamples of chamber out¯ow air were collected in Douglas bags (Flatt et al., 1958). The samples of out¯ow and incoming air collected were analysed for oxygen by a dual type Paramagnetic Oxygen Analyser (Servomex Taylor, Model OAT 184) for carbon dioxide by a modi®ed Sonden apparatus with a 100 ml burette and methane by IR gas Analyser (Analytical Development, Hoddesdon, UK, Model 300). 2.4. Chemical analysis Dried samples of feed and faeces were reduced to a particle size of 40 -mesh by a mill (Laboratory Construction, Kansas City, MO, USA, Model 960). Representative samples of feeds, faeces and urine were taken for analysis. The DM content of feed and faeces were determined by oven drying at 10058C overnight, while OM was determined by ashing in a muf¯e furnace for 3 h at 5508C. Faecal samples for GE estimation were dried at 488C and the urine samples were kept in a deep freeze condition without any preservative. The GE content of feed, faeces and urine was measured by complete ignition under oxygen pressure in a Gallenkamp Ballistic Bomb Calorimeter. The nitrogen content of feed, faeces and urine was analysed by steam distillation using a Kjeltec Auto 1030 Analyser (Tecator, Sweden) following Kjeldahl digestion. The nitrogen, EE, CFi and NFE was determined as per AOAC (1984). 2.5. Calculations and statistical analysis To calculate the digestible energy (DE) intake faecal energy was subtracted from GE intake. The metabolizable energy (ME) intake was calculated by subtracting the energy loss through methane and urine from DE intake. Energy content of methane was considered to be 9.45 kcal per litre (Brouwer, 1965). Energy balance was determined by subtracting the heat loss calculated as per Brouwer (1965) equation from ME intake. H ˆ 16:175O2 ‡ 5:021CO2 ÿ 2:167CH4 ÿ 5:987N; where H is the heat production (kJ dÿ1), O2 the volume

16

B. Sahoo et al. / Small Ruminant Research 35 (2000) 13±19

of oxygen consumed (l dÿ1), CO2 the volume of carbon dioxide produced (l dÿ1), CH4 the volume of methane produced (l dÿ1) and N is the amount of nitrogen excreted in urine (g dÿ1). Data on methane production and energy balance measurements were subjected to analysis of variance for a randomized design (Snedecor and Cochran, 1967). If F-tests were signi®cant, treatment means were compared using Duncan's multiple range test (Steel and Torrie, 1960). 3. Results and discussion The chemical composition and GE content of feed stuffs used are in Table 1. Wheat straw from all the three treatments were free from mould. The GE content of wheat straw treated with urea plus calcium hydroxide was lower than those sprayed with urea and either stored or fed directly after feeding. This might be due to lower OM content in urea plus calcium hydroxide treated wheat straw. However, no de®nite trend of effect was observed on the crude ®bre content

of straw due to different treatments. The crude protein content of wheat straw in all the three treatments were similar at the time of feeding. The DM intake in treatment III was higher (P<0.05) than that of treatment II. However, there was no signi®cant difference between treatments I and III and between I and II. The low intake in treatment II may be due to the unpleasant smell of urea freshly spread on straw and its lower digestibility. Moreover, improvement in DM intake by sheep fed on urea or urea plus calcium hydroxide treated straw might have been due to softness of the straw after treatment which increased fragility and greater susceptibility to mechanical reduction during rumination as has been reported by several workers (Saenger et al., 1982; Zorilla-Rios et al., 1985). Consumption of DM in ruminants fed on all roughage diets is related to the rate of fermentation in the rumen which in turn is related to the rate of passage. The higher the rate of passage, the more the DM intake. The DM digestibility in treatment II was lower than that of treatments I and III which did not show signi®cant difference between them. Similar trend was observed in OM digestion (Table 2).

Table 1 Chemical composition (g kgÿ1 DM) and gross energy (MJ kgÿ1 DM) content of different rations Attributes

Organic matter

Crude protein

Crude fibre

Ether extract

Nitrogen-free extracts

Gross energy

Wheat straw, untreated Wheat straw, treated with 4% urea (21 days storage time) Wheat straw, sprayed with 1.5% urea prior to feeding Wheat straw, treated with 3% urea‡3% calcium hydroxide (21 days storage time)

879 891 882 858

35 78 79 76

384 411 364 384

8 8 9 9

452 394 430 389

17.6 17.8 18.2 17.4

Table 2 Dry matter intake and digestibility of nutrients in sheep

Number of animals Live weight (kg) Dry matter intake (g dÿ1) (g kgÿ1 W0.75 dÿ1) Dry matter digestibility (%) Organic matter digestibility (%) Crude protein digestibility (%)

Treatment I

Treatment II

Treatment III

SEM

5 43.2 737.5ab 43.7ab 54.2a 58.3a 31.7

5 41.4 563.6b 34.9b 42.7 b 45.1b 38.0

5 44.2 844.9a 49.5a 50.9a 53.2a 33.0

± ± 76.42 4.13 3.56 3.84 2.92

Treatment I fed on wheat straw treated with 4 kg urea per 100 kg dry matter with a storage time of 21 days. Treatment II fed on wheat straw sprayed with 1.5 kg urea per 100 kg dry matter prior to feeding. Treatment III fed on wheat straw treated with 3 kg urea plus 3 kg calcium hydroxide per 100 kg dry matter with a storage time of 21 days. Values within a row not followed by the same letter differ (P<0.05).

B. Sahoo et al. / Small Ruminant Research 35 (2000) 13±19

17

production basis without considering the availability of digestible OM to the animals (Table 4). Treatment of wheat straw with urea alone and with urea plus calcium hydroxide with a storage time of 21 days have shown to increase the rate of degradation of OM (rich in ®bre content) and reduce rumen retention time. The reduced rumen retention time may in¯uence the methanogenic population as methanogens are slow growing and hence proliferate only under conditions of slow rumen particle dilution rate (Preston, 1972). However, Johnson and Johnson (1995) reported that as a greater amount of any carbohydrate fraction is fermented per day, whether it is a ®bre or starch, methane production is decreased. The fermentation of brewery and distillery products containing relatively available ®bre results in a surprisingly low methane production, generally one-half to one-third of that seen with common feed stuffs of comparable digestibility (Wainman et al., 1984). Moss et al. (1994) also reported a decreasing trend in methane energy loss as percent of gross energy intake when sheep was fed on ammonia treated wheat straw.

Greenhalgh and Reid (1967) showed that digestibility and palatability were of about equal importance in determining the voluntary intake of roughages by sheep. The GE intake in treatment III was signi®cantly higher than treatment II. No signi®cant difference was observed between treatments I and II and between I and III. Increased GE intake in treatment III was due to higher DM intake. DE intake in treatments I and III was higher than treatment II. It might be due to higher GE intake and improved digestibility of GE in both these treatments. Energy loss through urine was not affected by treatment. However, energy loss through methane as percent of DE intake was in¯uenced by treatment of straw. Feeding of wheat straw treated with urea alone or with urea plus calcium hydroxide and stored for 21 days reduced methane production (l kgÿ1) digested OM per day (Table 4) as well as methane energy loss as percent of DE intake (Table 3) than those in treatment II where animals were fed on wheat straw sprayed with urea solution prior to feeding. However, similarity was observed among the groups when methane was considered on per day Table 3 Distribution of energy in sheep fed on different rations Treatment I

Treatment II

Treatment III

SEM

Gross energy intake (kJ dÿ1) (kJ kgÿ1 W0.75 dÿ1)

13219ab 783ab

10550b 649b

14741a 862a

90.0* 87.3*

Digestible energy (kJ dÿ1) (kJ kgÿ1 W0.75 dÿ1) %GE

6970a 412a 53a

4579b 282b 43b

8046a 471a 55a

870.0** 42.2** 3.3*

Urinary energy (kJ dÿ1) (kJ kgÿ1 W0.75 dÿ1) %GE

128 8 1

192 13 2

177 11 1

70.0 4.7 0.5

Methane energy (kJ dÿ1) (kJ kgÿ1 W0.75 dÿ1) %DE

448 26 7b

393 25 9a

435 26 5b

40.0 2.0 0.7*

Metabolizable energy (kJ dÿ1) (kJ kgÿ1 W0.75 dÿ1) %GE %DE

6394a 377a 48a 92a

3993b 246b 38b 87b

7434a 435a 50a 92a

810.0** 36.9** 3.3** 1.2**

Values within a row not followed by the same letter differ (P<0.05). *P<0.05.

**

P<0.01.

18

B. Sahoo et al. / Small Ruminant Research 35 (2000) 13±19

Table 4 Methane production and energy balance in sheep on different rations Treatment I

Treatment II

Treatment III

SEM

Methane production (l dÿ1) (l kgÿ1 digested OM dÿ1)

11 30b

10 46a

11 29b

1.1 5.2

Heat production (kJ dÿ1) (kJ kgÿ1 W0.75 dÿ1)

4487 266

4525 284

4535 265

420.0 19.6

Energy balance (kJ dÿ1) (kJ kgÿ1 W0.75 dÿ1)

‡1907a ‡113a

ÿ533b ÿ40b

2899a ‡170a

630.0 37.1

Treatment I fed on wheat straw treated with 4 kg urea per 100 kg dry matter with a storage time of 21 days. Treatment II fed on wheat straw sprayed with 1.5 kg urea per 100 kg dry matter prior to feeding. Treatment III fed on wheat straw treated with 3 kg urea plus 3 kg calcium hydroxide per 100 kg dry matter with a storage time of 21 days. Values within a row not followed by the same letter differ (P<0.01).

Metabolizable energy intake and metabolizability of gross energy in groups I and III were also signi®cantly increased than those in group II (Table 3). There was no signi®cant difference between groups I and III. As metabolizability of the gross energy was similar in groups I and III, it seems that treatment of wheat straw with urea plus calcium hydroxide has comparable effect to that of urea alone with a storage time of 21 days. The nitrogen balance was 1.67, 0.70 and 2.46 g dÿ1 in groups I, II and III, respectively. The nitrogen balances in groups I and III were signi®cantly higher than that of group II whereas, there was no signi®cant difference between groups I and III. 4. Conclusion It is concluded that treatment of straw with urea and/or a mixture of urea with calcium hydroxide followed by storage can improve digestibility compared to spraying with urea solution prior to feeding and also reduce methane production per kg digested OM and increase energy balance. References AOAC, 1984. Official Methods of Analysis, 14th ed. Assoc. Off. Agric. Chem., Washington, DC, pp. 69±88. Brouwer, E., 1965. Report of sub-committee on constants and factors. In: Proceedings of the Third EAAP Symposium on

Energy Metabolism. Publication no. 11, Academic Press, London, pp. 441±443. Bull, L.S., Kennett, W.S., 1973. Open circuit equipment for calorimetric studies with animals of several sizes. In: Proceedings of the Sixth Symposium on Energy Metabolism of Farm Animals. Hohenheim, Germany, pp. 253±256. Flatt, W.P., Waldo, D.R., Sykes, J.F., Moore, L.A., 1958. A proposed method of indirect calorimetry for energy metabolism studies with large animals under field conditions. In: Proceedings of the First EAAP Symposium on Energy Metabolism. Principles, Methods and General Aspects. Copenhagen, 15±19 September, pp. 101±107. Greenhalgh, J.F.D., Reid, G.W., 1967. Separating the effects of digestibility and palatability on food intake in ruminant animals. Nature (London) 214, 744. ICAR, 1985. Final report (1967±1985). All India Coordinated Research Project on ``Utilization of agricultural byproducts and industrial waste materials for evolving economic rations for livestock'' (Indian Council of Agricultural Research), NDRI, Karnal, India, pp. 28±32. Jackson, M.G., 1978. Treated straw for animal feeding. FAO Animal Production and Health, Paper no. 10, FAO, Rome, pp. 25±27. Johnson, K.A., Johnson, D.E., 1995. Methane emissions from cattle. J. Anim. Sci. 73, 2483±2492. Khan, M.Y., Joshi, D.C., 1983. A new simplified open-circuit respiration equipment for sheep ± a note. Indian. J. Anim. Prod. 15, 34±36. Leng, R.A., 1991. Improving ruminant production and reducing methane emissions from ruminants by strategic supplementation. EPA/400/1-91/004, US Environmental Protection Agency, Washington, DC, pp. 6±10. Moss, A.R., 1993. Methane: Global Warming and Production by Animals. Chalcombe, Canterbury, UK, 105 pp. Moss, A.R., Givens, D.I., Gransworthy, P.C., 1994. The effect of alkali treatment of cereal straws on the digestibility and methane production by sheep. Anim. Feed Sci. Tech. 49, 245±259.

B. Sahoo et al. / Small Ruminant Research 35 (2000) 13±19 Preston, T.R., 1972. Molasses as an energy source for cattle. World Rev. Nutr. Dietet. 17, 250±311. Rai, S.N., Mudgal, V.D., 1988. Feeding of treated straw for efficient utilization and production by Murrah buffaloes. Buffalo J. 2, 161±172. Saenger, P.F., Lemenager, R.P., Hendrix, K.S., 1982. Anhydrous ammonia treatment of corn stover and its effect on digestibility, intake and performance of beef cattle. J. Anim. Sci. 54, 419± 425. Snedecor, G.W., Cochran, W.G., 1967. Statistical Methods, 6th ed. IBH Publishing, Calcutta, pp. 258±296. Steel, R.G.D., Torrie, J.H., 1960. Principles and Procedures of Statistics, 2nd ed. McGraw-Hill, New York, pp. 187±188.

19

Verma, M.L., 1983. Practical aspects of treatment of crop residues. In: Pearce, A.R. (Ed.), The Utilization of Fibrous Agricultural Residues. Australian Governmet Public Service, Canberra, pp. 85±94. Wainman, F.W., Dewey, P.J.S., Brewer, A.C., 1984. Feedstuffs Evaluation Unit. Fourth report. Rowett Research Institute, Aberdeen, UK. Zaman, M.S., Owen, E., 1990. Effect of calcium hydroxide or urea treatment of barley straw on intake and digestibility in sheep. Small Rumin. Res. 3, 236±248. Zorilla-Rios, J., Owens, F.N., Horn, G.W., McNew, R.W., 1985. Effect of ammoniation of wheat straw on performance and digestion kinetics in cattle. J. Anim. Sci. 60, 814±821.