J Agrobiol 27(2): 93–102, 2010 Journal of DOI 10.2478/s10146-009-0015-y ISSN 1803-4403 (printed) AGROBIOLOGY ISSN 1804-2686 (on-line) http://joa.zf.jcu.cz; http://versita.com/science/agriculture/joa

ORIGINAL ARTICLE

Utilization of wheat straw in sheep: Using an applicable method of chemical treatment

Vaheid Chekani-Azar1, Saeid Chekani-Azar2

1Department of Animal Science, Islamic Azad University, Kashmar Branch, Kashmar, Iran 2Young Researchers Club, Islamic Azad University, Shabestar Branch, Shabestar, Iran

Received: 6th October 2010 Revised: 20th December 2010 Published online: 29th December 2010

Abstract As part of research on utilization of straw as a feedstuff for small ruminants, wheat straw (WS) was pretreated with a warmed solution (4%) of NaOH (sodium hydroxide) and then treated with SO2 (sulphur dioxide) gases of different sulphur levels (0, 1, 2 and 4 percent, weight/weight of dry matter) for two periods of 1 and 2 smoking days. The chemical composition, and dry matter degradability (DMD) of the neutral detergent fibres (NDF), acid detergent fibres (ADF) and acid detergent lignin (ADL) in sheep rumen was determined, as was also the intake of the treated straw and the performance of Ghizle strain lambs. To estimate rumen DMD, treated WS samples were immersed in the rumen for a 72 h incubation period using the nylon bag (in sacco) technique. The chemical composition of the treated WS was changed with either one of NaOH or NaOH+SO2 prior to the rumen incubation, and the amounts of lignin, cellulose, hemicelluloses and silica significantly decreased specially in the SO2-smoked wheat straw. Dry and organic matter decreased non-significantly (P>0.05). The rumen DMD rate of the WS SO2-treated for a period of 48 hours did show higher values (P<0.01) compared to those smoked during 1 day. In sacco degradation also significantly decreased NDF, ADF and ADL. The best results were observed with WS SO2 samples smoked to 4% level during 2 days, followed by 2% level with the same smoking period. Although, a higher intake of treated WS was calculated for those smoked by 2% SO2 gas for a period of 1 d, the best performance was observed in lambs fed WS treated by NaOH+SO2 for a period of 2 days. It is concluded that chemical treatment of wheat straw by NaOH (4%) solution and SO2 (2%) gas smoking for a period of 2 days, can be used as an applicable method on a farm scale for better utilization of WS as a feedstuff for small ruminants such as sheep. Key words: sulphur dioxide; sodium hydroxide; degradability; wheat straw; performance; sheep

Introduction  Vahied Chekani-Azar, Department of Animal Science, Islamic Azad University, Kashmar Processing methods for wheat straw and other Branch, Kashmar, Iran grain straw have been investigated to determine  [email protected] whether they will enhance their nutritional value for livestock. Consequently, by-product foods are

93 Journal of Agrobiology, 27(2): 93–102, 2010 becoming increasingly more important in the (Berger et al. 1991, Galetti 1991, Ben-Ghedalia food and fibre system because they are available et al. 1994, Yosef et al. 1994). The dry treatment for use as livestock feeds at competitive prices method in which straw is simply sprayed with a relative to other commodities (Grasser et al. 1995). limited volume of an alkali solution, overcomes The benefit of such processing depends upon the the obvious disadvantages of the older Beckmann animal species and production level. In sheep method with a high water requirement and high for example the impact of differently processed dry matter losses, and makes the industrialization wheat straw is varied. On the one hand, chemical of straw treatment possible. However, the quality treatment of straw has been shown a to produce of Beckmann-treated straw is higher than better degradability and digestibility (Varvikko that of spray-treated straw. Hence, a modified and Lindberg 1985, Berger et al. 1991, Yosef et Beckmann process has been recognized as the al. 1994, Brown and Kunkle 2005), but on the best wet treatment method because it eliminates other hand, it is well-known that it also decreases dry matter loss, environmental pollution and palatability and intake of straw, especially when also, drastically reduces water requirements. treated with sulphur dioxide (SO2) (LeSoning and Sodium hydroxide (NaOH) is the most effective Klopfenstein 1981, Nasseven and Kincaid 1992, in this regard because, it can effectively dissolve Mehrez and Orskov 1997). lignin, silica, and hemicelluloses (Ben-Ghedalia Agricultural by-products have many uses and Yosef 1994). in Asia. The objectives of processing methods On the other hand, for farm scale treatment, of feedstuffs or by-products such as straw are the dry method can be used on the individual to increase the degradability and subsequently farm. It is simple and equipment costs can usually the digestibility, voluntary consumption and be paid by the individual farmer. In this method, digestible energy intakes. For these purposes, dry straw is sprinkled or sprayed with a diluted the main methods have been classified broadly NaOH solution so that it is uniformly wetted. into physical (by grinding the material into ball When straw is spray-treated with 60–120 l of mills and pressure cooking), chemical (by the NaOH solution (i.e.bulk treatment) it can be use of alkalis or other chemicals like chlorine) stacked, ensiled or NH3-treated by stacks under and biological (by culturing certain specific types plastic sheet and also can be stored from a month of fungi on straw). These processing methods to a year. It has been concluded that if the straw have been used either singly or in combination is treated in bulk with NaOH there can be a bonus (Varvikko and Lindberg 1985). The reported of enhanced effectiveness of the added alkali. results have shown that a combination of two Significant effects have been reported when the or three methods together can be more effective straw which has been spray-treated with NaOH (Dryden and Leng 1988, Nasseven and Kincaid is treated once more with sulphur dioxide (SO2) 1992, Kindsigo and Kallas 2006). The physical gas. Oxidizing agents act by disruption of the treatments such s size reduction, result in bonds in the lignocellulosic complex and within increases in the surface area of cellulosic and the cellusosic fraction (Miron and Ben-Ghedalia lignocellulosic residues and also, decrease the 1994). The results of many experiments on alkali- crystallinity which can increase susceptibility treated straw by researchers have shown that to chemical action or enzymatic attack (Oshea the chemical treatment of wheat straw by NaOH and Baldwin 1986). But processing of residues, and SO2 gas has had significant effects on the particularly microbial processing, can introduce degradability of cellulosic and lignocellulosic problems of nutritional and toxicological materials and therefore on their digestibility acceptability (Djajanegara and Doyle 1989). (Miron et al. 2001 a, b, Brown and Kunkle 2005), Chemical processing methods of straw are better but it also affects the palatability and hence the than other methods, especially treatment in the intake of chemically treated straw (Ben-Ghedalia form of mould, or wet and heat treating (Oshea and Miron 1984, 2001). and Baldwin 1986, Ben-Ghedalia et al. 1994, In the current study, we investigated the Kindsigo and Kallas 2006). effects of the chemical treatment of wheat straw With regard to issues such as cost, effectiveness, by a dilute sodium hydroxide (NaOH, 4%) solution and suitability under different conditions, many and different levels of sulphur dioxide gases chemicals such as alkali [NaOH, Ca(OH)2 or (SO2; 0, 1, 2, 4%) for a smoking period of 1 or 2 NH3] and oxidizing agents [SO2, NaClO2 (or days, corresponding to the traditional chemical ClO2), H2O2, O3, etc. ] by either “wet” or “dry” processing of raisin in East Azerbaijan province, methods have been tested for straw treatment Iran. We explored the use of this method in Asia

94 Journal of Agrobiology, 27(2): 93–102, 2010 for the chemical processing of by-products, its straw was then dried in free sunny weather for a chemical composition, in sacco degradability and period of 12 h. voluntary consumption of wheat straw in male sheep. Animals, feeds and feeding The amount of 5 grams from either of the treated samples were used for an incubation time of 72 h MATERIALS AND METHODS by means of the in sacco nylon bag technique (AFRC 1992), in which bags were suspended in Treating samples the rumen of the sheep and then the rumen dry The wheat straw (WS) samples with approximate matter degradability (RDMD) was calculated. In size of 3–4 centimetres were supplied by a this part of the presented study, four fistulated threshing machine. Chemical treatment of wheat sheep (Ghizle strain, 53±2.5 kg) were used and straw was carried out in a way similar to the nylon bags, 5 × 12 cm in size with a pore size traditional method of SO2 treatment of raisins. of approximately 50 µm and a string of 50 cm As with the treatment mentioned, wheat straw length, were used in a series of in sacco ruminal is uniformly wetted with a dilute NaOH (4%) incubations. Dried, treated samples were solution, and then SO2 smoked by burning sulphur previously ground in a Wiley mill with a sieve of in a metallic dish which is placed in a wooden cage 2 mm size. (0.8 × 0.5 × 0.3 meters) and completely covered The fistulated animals were offered a diet of by thick plastic. Chopped straw (two kilograms 60% hay and 40% concentrate including lucerne, per pen) and required amounts of sulphur were barley and soybean meal twice a day at 08:00 h weighed and placed on the floor of the prepared and 14:00 h and had free access to water, and pens. Suitable metallic dishes were previously also minerals and vitamins that were provided prepared and placed in fixed cages for burning sufficiently for microbial activity (NRC 2001). yellow sulphur (0, 1, 2 and 4 percent, weight/ In the supplementary part of the trial, and weight of dry matter, W/WDM). The metallic to determine the voluntary consumption of container used (1.5 × 0.5 × 0.5 metres) had been the treated wheat straw, a CRD with factorial prepared by a well known farmer from Maragheh arrangement (4 × 2) similar to the statistical city environs in Chekan village. All chemical design for the determination of the chemical materials such as yellow sulphur, NaOH (4% composition and rumen degradability of wheat ready) solution and containers were previously straw, was conducted with a total of 27 lambs purchased from an agricultural tools shop in (Ghizle strain, 42±2 kg BW) that were assigned, Tabriz, East Azerbayjan, Iran. within strata, to 9 experimental (8+1 control) The presented study was conducted on the groups with a total of 3 lambs per treatment. basis of a completely randomized design (CRD Dietary treatments were: with factorial arrangement, 4 × 2) for chemical Dry WS (control, S1N1), WS treated with 0% composition, rumen degradability and voluntary SO2+4% NaOH for 24 and 48 hours (S1N2 day1 and intake of chemical treated wheat straw. In the S1N2 day2), WS treated with 1% SO2+4% NaOH first part of the chemical processing, dry wheat for 24 and 48 hours (S2N2 day1 and S2N2 day2), straw was thrown inside the plastic containers WS treated with 2% SO2+4% NaOH for 24 and lattice and then immersed in a special metallic 48 hours (S3N2 day1 and S3N2 day2), WS treated container which contained a warm (commonly, with 4% SO2+4% NaOH for 24 and 48 hours (S4N2 50±5 ºC) and dilute NaOH (4%) solution for a period day1 and S4N2 day2). of one minute and finally, the plastic container The experimentally treated wheat straw containing the wet straw was removed from the were added to 40% concentrates of the same diet solution and transferred within wooden cages comprising lucerne, barley and soybean meal that after a suitable time (generally, 5–10 minutes) were fed to each of the lambs each day. 60% of had expired to drain the NaOH solution from the the diet consisted of hay and 40% of the treated straw. In step 2, the wetted straw transferred wheat straw which were fed to the animals within the plastic covered cages, was treated by at 14:00 h daily, and the concentrates in two different levels of SO2 gases via burning sulphur. equal portions at 09:00 h and 16:30 h. The small The sulphur amount was controlled and the fire ruminants were placed into individual pens and was regulated to ensure adequate smoking over fed their respective diets with sufficient minerals the 1 or 2 days of the practical treatment periods and vitamins and also water to allow ad libitum (24 and 48 hours, respectively). The treated wheat consumption for 60 d. Treated WS samples from

95 Journal of Agrobiology, 27(2): 93–102, 2010 each treatment group were added to concentrates ANOVA using the GLM procedures of SAS (SAS to the extent of 40%, in consideration of the 1998) and means were compared by the Duncan probable toxic effect of sulphur dioxide and its test. For significant differences (P<0.01), means subsequent detriments on animal health and were compared by the LSD method of the same product. SO2 can be harmful in high levels during statistical package. treatment (Setterstrom 1940).

Degradability and performance calculation RESULTS The bags were removed from the rumen and washed with water and dried in an oven The straw based on high fibre concentrations was (Universal Uven Uemmert Germany, with force judged to be the mainstay of the diet if treated air circulation, model UFB 400) at 60 °C for 24 h with alkali (NaOH) and oxidizing agents such as and then weighed. The dry matter degradability SO2 gas. Treated straw can replace hay or silage of the SO2-treated-WS was calculated via the in the diet if the difference in protein content weight difference in the first straw sample between the treated straw and the hay or silage through the remaining sample weight after a is made good with an oil meal supplement. The rumen incubation time of 72 h. Feed residues predominant chemical composition of the NaOH were recovered from each bag and stored pending and SO2-treated wheat straw after 24 and or different analyses such as the Kjeldahl nitrogen. 48 hours application of smoking in a farm scale Approximately 1.0 g of sample was weighed prior to the rumen incubation step, showed the within each bag to provide a ratio of sample utilization of this agricultural by-product after a weight to surface area. practical chemical treatment to be a suitable small The sheep were weighed every week and data ruminant feedstuff because of the intensification on weekly food intake, food conversion ratio (FCR) of its nutritive value (Table 1). In the current and daily weight gain (DWG) were recorded in study, chemical treatment of WS by method each replicate group and the body weight (BW) applied as mentioned predictably decreased the presented as growth performance at the end of typical concentrations in wheat straw of cellulose trial. and lignin (Table 1, P<0.05) which caused an increase of straw digestibility (Table 2) because of Chemical composition an increase the intake of digestible energy (DE), All feed samples were ground to pass a 1-mm although voluntary consumption of treated WS screen. Dry matter (DM) was determined by was affected by the sulphur dioxide gas (Table 3). oven drying at 110 °C for 10 h. Organic matter The values of other chemical components of wheat was determined indirectly, by difference in the straw (DM, OM, silica, CP and ash) were changed ash content (AOAC 1995). The ash content was non-significantly. determined by the incineration of 1.0 g samples placed in a muffle furnace (LMF4 from Carbolite, SO +NaOH treatment of wheat straw, Bamford, Sheffield UK) maintained at 550 °C 2 RDMD, ADF, NDF and ADL contents for 5 hours. Crude protein (% total nitrogen × 6.25) was determined by the Kjeldahl method The results of SO2 plus NaOH treatment of (Kjeldahl 1883), using 1.0 g samples. Silica was wheat straw are shown in Table 2. The applicable estimated according to method 3.005 of the AOAC treatment of wheat straw with SO2 gas plus (1984). Cellulose, hemicellulose and lignin were NaOH solution, increased the rumen dry matter determined as in Bailey (1967). The neutral degradability (RDMD) and decreased the detergent fibres (NDF) and acid detergent fibres content of ADF, NDF and ADL (P<0.01) after (ADF) were measured according to the methods an incubation time of 72 h. Better findings were described by Van Soest et al. (1991). observed when NaOH (4%)-wetted straw was once again treated with SO2 gases from different levels Statistical analysis of sulphur for a period of 48 hours compared with A completely randomized design with factorial other groups, especially those SO2-smoked over arrangement (4 × 2) was used for the current 24 hours (Table 2). Therefore, an increase of SO2 experiment containing 4 levels of sulphur dioxide smoking time for a period of 2 days (48 hours), including 0, 1, 2 and 4 percent (W/WDM) for leads to a decrease of ADF, NDF and ADL 1 or 2 days of the practical smoking process. concentrations in the treated-WS samples and The completely randomized design with four subsequently increases it’s RDMD after use of a replicates and treatment were subjected to 72 h in sacco incubation.

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Table 1. Chemical composition of non-treated, NaOH-wetted and SO2-smoked wheat straw for a period 24 and 48 hours treatment prior to in sacco incubation or feeding (means of eight observations per treatment)

ITEM (%) DM OM Cellulose H-celluloses Lignin Silica CP Ash

a a S1N1 92.00 96.50 39.30 26.40 8.85 5.80 5.61 15.00 b b S1N2 day1 90.10 96.94 36.21 23.42 6.72 4.44 5.45 15.40 b c S2N2 day1 91.15 95.75 36.25 22.55 6.25 4.50 5.58 15.68 b c S3N2 day1 91.17 95.80 36.15 22.57 6.25 4.42 5.40 15.80 c d S4N2 day1 91.62 95.12 35.32 21.97 5.92 4.17 5.25 15.45 b b S1N2 day2 91.39 95.70 36.65 23.27 6.52 4.68 5.55 15.55 bc bc S2N2 day2 91.75 95.22 35.80 21.60 6.37 4.27 5.54 15.50 abc c S4N2 day2 91.17 95.75 35.87 21.67 6.12 4.30 5.46 15.60 d d S3N2 day2 91.82 95.65 35.07 20.77 5.75 4.02 5.54 15.75 SEM 0.101 0.301 0.513 0.308 0.131 0.146 0.097 0.205 Significant level SO gas 2 P<0.75NS P<0.11NS P<0.07NS P<0.55NS P<0.015* P<0.77NS P<0.98NS P<0.42NS level NaOH gas P<0.12NS P<0.07NS P<0.04* P<0.17NS P<0.005* P<0.17NS P<0.11NS P<0.10NS level

SO2 level × smoking P<0.22NS P<0.08NS P<0.03* P<0.09NS P<0.001** P<0.05NS P<0.06NS P<0.10NS day

DM = dry matter; OM = organic matter; H-celluloses = Hemicelluloses; CP = crude protein. NaOH = sodium hydroxide, SO2 = sulphur dioxide. S1N1 = control, S1N2 = 0% SO2+4% NaOH, S2N2 = 1% SO2+4% NaOH, S3N2 = 2% SO2+4% NaOH S4N2 = 4%

SO2+4% NaOH; Day1 and day2 = SO2 smoking for periods of 24 and 48 hours respectively. NS = not significant; * = P>0.05; ** = P<0.01; SEM = standard error of the mean. a–d Values in the same row and variables with no common superscript differ significantly.

Fig. 1. The comparison of results of consumption rate of chemical treated wheat straw (A) and concentrate (B) after a single and multiple treatment with NaOH (4%) solution+SO2 gases for a smoking periods of 1 and 2 days. DM = dry matter; WS = wheat straw. S1N1 = control, S1N2 = 0% SO2+4% NaOH, S2N2 = 1% SO2+4% NaOH, S3N2 = 2% SO2+4% NaOH, S4N2 = 4% SO2+4% NaOH; Day1 and day2 = SO2 smoking for periods of 24 and 48 hours respectively.

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Table 2. The effects of NaOH (4%) solution and different levels of SO2 gases for periods of 24 and 48 hours on RDMD, ADF, NDF and ADL of wheat straw in rumen of sheep (53±2.5 kg BW) measured using nylon bag technique (in sacco) (means of twelve observations per treatment)

Item (% DM) Treatment RDMD ADF NDF ADL

a a a a S1N1 45.05 59.25 50.00 5.70 a a a b S1N2 day1 46.13 59.85 48.13 5.66 b b a b S2N2 day1 50.99 58.10 48.13 5.67 ac bcd ab b S3N2 day1 52.15 55.00 48.00 5.57 bc d c c S4N2 day1 53.28 51.42 46.20 5.12 a a b bc S1N2 day2 46.57 59.00 47.40 5.53 abc bc ab b S2N2 day2 55.77 57.58 47.05 5.47 abcde d cd bcd S3N2 day2 62.56 53.81 45.00 5.05 e e d d S4N2 day2 67.33 48.00 43.01 4.77 SEM 1.75 0.93 0.91 0.063 Significant level

NS SO2 gas level P<0.0428* P<0.0350* P<0.0919 P<0.0919* NaOH gas level P<0.0225* P<0.0018*** P<0.0498* P<0.0919**

NS SO2 × NaOH gas level P<0.0018** P<0.0085*** P<0.6675 P<0.0919***

DM = dry matter; RDMD = rumen dry matter degradability; ADF = acid detergent fibre; NDF = neutral detergent fibre; ADL = acid detergent lignin. S1N1 = control, S1N2= 0% SO2+4% NaOH, S2N2 = 1% SO2+4% NaOH, S3N2 = 2% SO2+4% NaOH S4N2 =

4% SO2+4% NaOH; Day1 and day2 = SO2 smoking for periods of 24 and 48 hours respectively. NS = not significant; * = P<0.05; ** = P<0.01; *** = P<0.001; SEM = standard error of the mean. a–e Values in the same row and variable with no common superscript differ significantly.

Table 3. The effect of treatment of straw by NaOH (4%) solution and different levels of SO2 gases in 24 and 48 hours smoking periods on the performance of growing lambs (means of eight observations per treatment)

Performance traits Treatment Feed intake, g DM/day Daily gain, g g feed/g gain

a a a S1N1 876.05 61.20 14.25 a a a S1N2 day1 883.76 64.50 13.70 b b a S2N2 day1 885.60 64.82 13.44 ac bcd ab S3N2 day1 884.80 65.37 13.53 bc d c S4N2 day1 882.37 64.60 13.65 a a b S1N2 day2 886.16 65.16 13.58 abc bc ab S2N2 day2 887.93 68.12 13.02 abcde d cd S3N2 day2 885.42 66.50 13.31 e e d S4N2 day2 852.53 62.75 13.58 SEM 1.75 0.308 0.145 Significant level

NS NS SO2 gas level P<0.0428 P<0.0350* P<0.0919 Smoking period P<0.0225** P<0.0018*** P<0.0498*

NS NaOH × SO2 gas level P<0.0018*** P<0.0085* P<0.6675

DM = dry matter. NaOH = sodium hydroxide, SO2 = sulphur dioxide. S1N1 = control, S1N2 = 0% SO2+4% NaOH, S2N2 = 1% SO2+4%

NaOH, S3N2 = 2% SO2+4% NaOH S4N2 = 4% SO2+4% NaOH; Day1 and day2 = SO2 smoking for periods of 24 and 48 hours respectively. NS = not significant; * = P<0.05; ** = P<0.01; *** = P<0.001; SEM = standard error of the mean. a–e Values in the same row and variables with no common superscript differ significantly.

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Although further treatment of WS with SO2 values were detected in high levels of SO2 gases gases was more effective, pretreatment with for a period of 48 hours smoking. NaOH (4%) by a local method corresponding The results from the presented study were to the method of chemical treatment of raisins in agreement with other findings by Varvikko in East Azerbaijan could be effective for better and Lindberg (1985), Galetti 1991, Yosef et al. chemical processing by increasing the disruption (1994) and Brown and Kunkle (2005). They of bonds in the lignocellulosic complex and within reported that the chemical treatment of straw the cellulosic fraction (Miron and Ben-Ghedalia showed a better utilization on degradability and 1994) (Fig. 1). subsequently digestibility. Sodium hydroxide (NaOH) was found to be the most effective in this Chemically treated wheat straw intake by regard because it can be effective in dissolving lambs lignin, silica, and hemicelluloses (Ben-Ghedalia and Yosef 1994, Boudet 2000). On the other hand, In the current study, the results of wheat oxidizing agents such as SO , NaClO (or ClO ), straw treatment by NaOH (4%) solution and 2 2 2 H2O2, O3, etc. act by disruption of bonds in the different levels of SO2 gas smoking for periods lignocellulosic complex and within the cellulosic of 24 and especially 48 hours on treated-WS and fraction (Miron and Ben-Ghedalia 1994) which concentrate intake (Fig. 1) and also results related can be effective to better dissolution after to the performance of growing lambs (Table 3) initial wetting with the NaOH (4%) solution as revealed a palatability loss in the chemically previously suggested by Berger et al. (1991). processed straw. The voluntary consumption of WS treated by 4% SO2+4% NaOH for 1 and RDMD, ADF, NDF and ADL contents of especially 2 days (S4N2 day2) was decreased. A wheat straw after a single or twofold higher intake of treated WS was calculated for treatment those smoked by 2% SO gas for a period of 1 d, 2 The results presented in the current study and the best performance was observed in lambs related to SO -treatment of wetted-WS are in fed twofold-treated WS for a period of 2 days SO 2 2 agreement with the results of Ben-Ghedalia (2%) smoking. and Miron (1984, 2001). Yosef et al. (1994) by investigation of the characterization of some cell wall components of untreated and SO2-treated DISCUSSION wheat straw, and Mehrez and Orskov (1997) with a study of the artificial fibre bag technique The objective of the current study was an for determining the digestibility of feeds in the evaluation of the utilization of wheat straw in rumen, have previously documented that high sheep as a small ruminant corresponding to an ADL (acid detergent lignin), NDF and ADF values applicable method of chemical treatment on a decrease the intake of roughage, especially straw, farm scale. It was expected that a substantial and by-products treated by oxidizing agents proportion of the treated dry matter would be can be efficient in the digestibility of chemical degraded in the rumen after an incubation time composition and degradability of cellulosic and of 72 h, because it seemed that the selected local lignocellulosic materials, via the disruption of bonds within the cellulosic fraction of the pattern of chemical treatment (SO2+NaOH) could be more efficacious in dissolving the lignocellulosic lignocellulosic complex (Miron and Ben-Ghedalia fractions of wheat straw. 1994). However, differences in the results presented might be related to wheat variety type, treatment process, farm conditions and numbers Chemical composition of samples in different experiments. A comparison the of chemical composition of the Many studies have indicated that the untreated with the treated wheat straw samples degradability and digestibility of dry matter showed the NaOH solution and sulphur dioxide in rumen increased after dissolution of lignin, to be efficient in dissolving lignin, silica, and silica, and hemicelluloses by dilute NaOH (4%) celluloses (P<0.05). NaOH-wetted wheat straw solution and especially the breakdown of bonds had a lower content of cellulosic and lignocellulosic in the lignocellulosic complex and within the materials compared with the control samples, cellulosic fraction by practical SO2 smoking while those smoked with SO2 gas showed lower during 24 and 48 h (Chandra and Jackson 1971, contents compared to other samples; the lowest Baker et al. 1975, Yosef et al. 1994, Boudet 2000).

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Ben-Ghedalia and Yosef (1994) reported that the S3N2 (2% SO2+4% NaOH for a period of 2 days NaOH 4% solution can be very effective in helping SO2 smoking). to maximum the effect of gas SO2 on disruption of Many experiments have been done on the bonds in the lignocellulosic complex and within assumption that it would improve the feeding the cellulosic fraction and subsequently break value of treated straw. The results of several of resisting grafts by microbial digestion. The experiments have shown that straw spray- polyhydric structures of cellulose and lignin treated with 60–120 1 of NaOH solution, has been molecule,s aromatic compounds of cell wall effective in increasing the performance of lambs plants, are sensitive to chemical oxidization by fed wheat straw diets containing 70% straw and gases such as SO2 (LeSoning and Klopfenstein 30% concentrate supplement and have increased 1981, Dryden and Leng 1988, Boudet 2000). 4-fold (Miron et al. 2001b). Therefore, an increasing RDMD in wheat straw It is concluded that in spite of a notable may be due to the break down of the ADF, NDF influence of 2 SO (4%) smoking during 2 days or ADL content of wheat straw treated with the on WS wetted by NaOH (4%) solution, a lower NaOH solution and different levels of SO2 gases, palatability of WS was detected. WS treatment which could be as a result of the depletion in by SO2 (2%) gas for a period of 2 days could be the lignin contents or could also be the result of effective as a applicable process of chemical breakdown of cell wall bonds during 2 or 4 days treatment of wheat straw without having smoking of the moist straws by sodium hydroxide quality losses of treated food on intake rate and (Boda 1990, Nasseven and Kincaid 1992). performance. On the other hand, Kindsigo and Kallas The results of many experiments on alkali- (2006) in a study of lignin degradation by wet treated straw by researchers have shown that oxidation; model water solutions, reported that chemical treatment of wheat straw by NaOH and the biodegradability of the remaining organic SO2 gas had significant effects on it’s digestibility, matter increased during the wet oxidation which chemical composition and degradability of is an appropriate method for the destruction of cellulosic and lignocellulosic materials (Miron very complex, multi-dimensional, and permanent et al. 2001 a, b, Brown and Kunkle 2005), but compounds, especially when temperature was can affect palatability and intake of chemical applied. In the method of our study, a dilute treated straw (Ben-Ghedalia and Miron 1984, solution (4%) of NaOH with a fire under the 2001). In the present study, treatment of wheat container contain solution was warmed up to straw with a warmed solution (4%) of NaOH plus 50±5 ºC for boosting the better effect of NaOH SO2 (2%) gas for a period of 48 h smoking had solution. Hence, using the current traditional and no effect on palatability accompanying with a multi chemical processing of wheat straw could better utilization during rumen degradation of facilitate treatment process of straw in large and treated WS. Therefore, it can be considered as small farms, provided that the proposed levels a applicable method of chemical processing of of NaOH from this presented study were used, wheat straw for agricultural farms where treated because sulphur dioxide (SO2) is toxic and can be WS can be useful as small ruminant feedstuff. harmful. Therefore, it can reduce the palatability of the treated food and subsequently it’s voluntary consumption. SO2 is a colorless, non-inflammable CONCLUSION gas with a strong, pungent, suffocating odor and soluble in water and ethanol (Setterstrom 1940). If wheat straw is wetted with a warm solution of NaOH and then treated with SO2 gases for Chemically treated wheat straw intake by 1 or 2 days there can be a bonus of enhanced lambs and performance effectiveness of the added alkali and temperature. The palatability of WS treated with 5% SO2 The rumen dry matter degradability and gas level after pretreated with NaOH (4%) thereupon chemical composition digestibility can significantly decreased (P<0.001) in comparison be improved by the suggested method applicable with other chemical processing groups, while for farm-scale treatment. However, Iran is one of SO2 smoking of straw with 2% level of sulphur the Asian countries that uses straw as a major for a period of 48 h did not affect palatability; source of roughage for livestock because cultivated also the highest feed intake, daily gain and green fodder is not sufficiently available. Also, therefore the best performance was detected in more work in these areas is necessary to detect the lambs fed diets containing WS treated with applicable results and study of different levels of

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NaOH, SO2 and other chemicals on types of straw Baker AJ, Millet MA, Satter LD (1975): Wood and and test diets in different criteria of feeding (ad woodbased residues in animal feeds. In Turbak libitum vs. restricted), the sex and age of animal AF (ed.): Cellulose technology research. A.C.S. and many more factors could have contributed to Symposium Series 10. American Chemical this variability. Society, Washington D.C., 75–105. Straw may also be “pre-treated” with other Ben-Ghedalia D, Miron J (1984): The digestibility chemicals such as NH3, Ca(OH)2 etc. at a relatively- of wheat straw treated with sulphur dioxide. J high moisture content. No applicable method for Agric Sci Camb 102: 517–520. chemical treatment of fibrous materials has been Ben-Ghedalia D, Yosef E (1994): Effect of isolation developed except for the method suggested in the procedure on molecular weight distribution of current study, but the scope for such a method wheat straw lignins. J Agric Food Chem 42: may prove to be great. The improvement in 649–652. degradability and subsequently of digestibility Ben-Ghedalia D, Miron J (2001): Digestion by is frequently used to express the effectiveness sheep of monosaccharide constituents of direct of straw treatment. However, in most cases this cut alfalfa silage made with SO2-treated wheat improvement is accompanied by a significant straw. Anim Feed Sci Technol 92: 175–183. increase in the straw intake. Ben-Ghedalia D, Yosef E, Miron J, Huttermann Hence, the application for a suitable duration A, Majcherczyk A, Milstein O (1994): of NaOH+SO2 to wheat straw or other similar low- Characterization of lignins in straw/rumen quality roughages, may be an efficient method of liquor and feces of sheep feed untreated and handling and treating wheat straw under village SO2 treated wheat straw. Anim Feed Sci conditions in Asian farms or other area of world Technol 47: 89–98. where straw is the staple feed. Berger E, Tigemeyer C, Bourquin LD (1991): Intake, digestibility, and in situ digestion kinetics of treated wheat straw and alfalfa ACKNOWLEDGMENTS mixtures fed to Holstein heifer. J Dairy Sci 74: 3524–3534. We would like to express our sincere gratitude to Boda K (ed.) (1990): Nonconventional feed stuffs Dr. Rezaa Valizadeh, distinguished professor of in the nutrition of farm animals. Elsevier, Animal Science in Ferdowsi University, Mashhad, Amsterdam. Iran for present his fixed idea related to applicable Boudet AM (2000): Lignins and lignification: chemical treatment of by-products for further selected issues. Plant Physiol Biochem 38: investigation. The authors are also grateful to 81–96. Dr. Habib Aghdam Shahryar, assistant professor Brown WF, Kunkle WE (2005): Improving the in Animal Science Department, Islamic Azad feeding value of hay by anhydrous Ammonia University, Shabestar Branch, for their scientific treatment. assistance in presented study. Chandra S, Jackson MG (1971): A study of various chemical treatments to remove lignin from coarse roughages and increase their REFERENCES digestibility. J Agric Sci 77: 11. Djajanegara A, Doyle PT (1989): Urea AFRC – Agricultural and Food Research Council supplementation compared with pre- (1992): Nutrient requirements of ruminant treatment. Effect on intake, digestion and animals: Protein technical committee on live-weight change by sheep fed rice straw. responses to nutrients. Nutr Abstr Rev Series Anim Feed Sci Technol 25: 21–36. B 62: 787–835. Dryden G, Leng RA (1988): Effect of ammonia AOAC (1984): Official methods of analysis. and sulfur dioxide gases on the composition Association of Official Analytical Chemists, and digestibility of barley starw. Anim Feed Washington, DC. Sci Technol 19: 121–133. AOAC (1995): Official methods of analysis. Galetti GC (1991): Production and utilization Association of Official Analytical Chemists, of lignocellulosics. Elsevier Appl Sci, Washington, DC. Luxembourg. Bailey RW (1967): Quantitative studies of Grasser LA, Fadel JG, Garnett I, DePeters EJ ruminants digestion. II. Loss of ingested (1995): Quantity and economic importance of carbohydrates from reticule rumen. J Agric nine selected by-products used in California Res 10: 15–32. dairy rations. J Dairy Sci 78: 962–971.

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