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Rice straw and rice hulls in feeding ruminants in Egypt

A M Nour
Department of Animal Production, Faculty of Agriculture, Alexandria University, Alexandria, Egypt


Introduction
Methods for improving the nutritive value
Supplementation with the deficient ingredients and inclusion rates of rice straw/hulls
Conclusion
References

Introduction

Rice straw represents an important summer crop by-product in Egypt. About 3.5 million tons of rice straw and 0.5 million tons of rice hulls are produced every year from the rice fields and rice milling process respectively. There is no practical use for these by-products, up till now, except for fuel. This paper reviews some research results relevant to the use of rice straw and rice hulls as feeds for ruminants in Egypt. The chemical composition of these materials is given in Table 1, showing the limiting factors for their utilisation by ruminants are low crude protein, high fibre and low available energy contents.

Table 1. Chemical composition of rice straw and rice hulls.

Ingredient

% on DM basis

Dry Matter %

Ash

Crude fibre

Crude protein

Ether extract

Nitrogen free extract

Total Digst. Nutr.

Rice straw

90.93

20.32

35.39

4.62

1.14

38.53

40.0

Rice hulls

96.40

20.51

48.55

1.79

0.83

28.32

21.4

Methods for improving the nutritive value

Physical treatments

Grinding

Grinding of straw increases its intake and leads to a higher digestible energy intake by some 30% (Jackson 1978). Grinding usually decreases digestibility, but at the same time increases net energy content. The effect of grinding is much less to nil when straw comprises 50% or less of the diet (Jackson 1978).

Steam processing

Steam-processing of low quality roughages has been recommended to increase energy availability (Bender et al. 1970), and in Table 2 some results are presented of the effect of such treatment on the in vitro digestibility of dry matter and volatile fatty acid production. Steam treatment had no effect on in vitro DMD of rice straw, but effectively increased DMD of maize cobs, bagasse and pith (Abaza et al 1981).

Table 2. Effect of steam treatment on in vitro dry matter digestibility (%) of rice straw compared with other roughages.

Item


Rice straw

Maize Cobs

Bagasse

Pith

Control

DMD

33.6

20.5

23.5

17.5

VFA

26.7

31.0

24.6

27.7

Steam treated

DMD

34.0

32.5

33.1

27.4

VFA

29,.1

41.4

32.3

33.6

Alkali treatment

Four methods of applying NaOH to rice straw (Nour et al 1987), were compared in order to select the optimum method to be used in the small farms in Egypt. Chopped rice straw was treated with NaOH by the methods of Torgrimsby (1971), Boliden (as described by Jackson 1978), Jackson (1977) and Wilson and Pigden (1964). Treated straws were compared with untreated rice straw in a feeding experiment with sheep fed a restricted amount of concentrate mixture. The results in Table 3 show that NaOH treatment of rice straw increased feed intake and digestibility of DM of rice straw, which was calculated by difference. The methods of Torgrimsby and Boliden appeared to be more effective than the other methods evaluated.

Table 3. Effect of different methods of NaOH treatment on the feed intake, dry matter digestibility and on TDN content of rice straw (calculated by difference)*


 

Without treatment

Method of NaOH treatment

Torgrimsby

Boliden

Jackson

Wilson & Pigden

Dry matter intake (kg/head/day)

0.59

0.81

0.76

0.70

0.60

%Dry matter digestibility

46.8

74.1

71.1

55.9

51.9

% TDN

44.6

71.2

63.6

49.2

46.5

* Source: Nour et al (1987)

Abou Raya et al. (1983) showed that boiling rice straw for one hour in water or in 0.2% Ca (OH)2, or in 0.2% NaOH greatly improves the nutritive value of rice straw (Table 4).

Table 4. Effect of short time alkali treatment of rice straw on its nutritive value *



Without treatment

Treated rice straws

boiled in water

boiled in 0.2% Ca (OH)2

boiled in 0.2% NaOH

DE Kcal/100g

191

225

206

215

SV %

21.5

29.8

28.6

35.5

TDN %

42.4

49.7

49.9

56.5

DP %

-1.35

0.15

0.10

-0.24

* Source: Abou Raya et al. (1983).

Ammonia treatment of rice straw, increased digestion coefficients of organic matter, crude protein, ether extract and crude fibre (Fahmy 1985). TDN content was also increased to 52.6 which represents a 10% improvement (Table 5). Ammonia treatment has the advantage in increasing both crude protein content and digestibility. When limited amounts of concentrates were added to rice straw the nutritive value of treated and untreated rice straw was improved (Table 5). Fahmy (1985) reported that alkali treatment resulted in increased water consumption and urine volume by some 2.5 - 3.0 fold.

Table 5. Effect of alkali treatment on feed intake digestibility coefficients and nutritive value of rice straw when fed with or without concentrates *


 

DM intake g/kg0.75

Digestibility coefficient %

OM

CP

EE

CF

NFE

TDN

Rice straw alone:

Without treatment

11.2

63.5

-

5.8

75.2

59.3

47.8

NaOH treated

12.9

79.5

-

16.7

94.4

63.8

51.8

NH3 treated

13.4

66.4

70.6

78.7

77.7

55.8

62.2

Rice straw + concentrates:

Without treatment

46.6

68.3

73.1

92.8

53.3

72.9

64.1

NaOH treated

33.5

66.8

65.3

94.9

52.2

67.3

63.2

NH3 treated

44.7

70.1

78.8

92.4

45.0

71.1

65.4

* Adapted from Fahmy (1985).

Microbiological treatment

Ensiling rice straw (whether treated or not) with berseem (Trifolium alexandrinum) resulted in a clear improvement in the performance and daily liveweight gain of fattening sheep (Table 6). This method of rice straw treatment exceeded in its beneficial effect any alkali treatment (N. Esmaiel 1983).

Mohsen et al (1983) showed that ensiling of rice straw with 6% molasses with or without monensin (5 ppm) increased its digestibility and nutritive value. The TDN% values were 55.03 and 52.83% when rice straw was ensiled with molasses and monensin or molasses respectively. Monensin is a biologically active compound that has been shown to alter silage fermentation.

Table 6. Feed consumption, daily liveweight gain and efficiency of feed utilization by lambs maintained on rations containing treated or untreated rice straw and silage.



Diet No:

1

2*

3

4*

Average feed consumption (kg DM/head/day)

Rice straw

0.39

0.32

-

-

Berseem silage

0.25

0.24

-

-

Silage of rice straw and berseem (1:1)

-

-

0.55

0.55

Concentrate mixture

1.17

1.17

1.18

1.18

TDN consumption

1.24

1.29

1.31

1.19

Number of animals

8

8

8

8

Experimental period (days)

95

95

95

95

Initial weight (kg)

36.68

38.62

38.68

38.68

Final weight (kg)

50.56

52.02

58.08

56.00

Daily gain (kg/head/day)

0.12

0.12

0.20

0.18

Feed efficiency (kg TDN/kg gain)

10.33

9.21

6.55

6.61

* Rice straw in diets 2 and 4 was previously treated with 5% NaOH.

Supplementation with the deficient ingredients and inclusion rates of rice straw/hulls

Badr and Abou Akkada (1965) reported that feeding ground rice hulls with 1st cut berseem, improved the digestibility of nutrients in sheep. (Results in Table 7 indicate that feed intake is improved by the addition of molasses and urea).

Shehata and Nour (1986) showed that straw fed with concentrates has a superior feeding value than concentrates alone. Results in Table 8 indicate that increasing the percentage of rice hulls in the diet increases the contents of ash and crude fibre, and decreases crude protein, ether extract and nitrogen free extract. Nour and El Shazly (1981) showed that coefficients of digestibility, nutritive value and nitrogen balance were higher for rations containing 35 and 40% rice hulls than those containing 60 or 70% rice hulls. The highest depression in measured parameters occurred when rice hulls was increased in the diet from 60 to 70%. Therefore, it is possible to include rice hulls in pelleted diets at the 60-70% level for maintenance and at 35-40% level for production. The presence of rice hulls in the diet improved the average daily liveweight gain of bulls (Table 9). No significant differences were found between the different groups in dressing percentage, carcass bone/muscle ratio.

Table 7. Effect of addition of molasses and urea on feed intake, nutritive value and cost of rice straw as a feed for ruminants.



Treatment

Rice straw alone

Rice straw + 5% molasses

Rice Straw + 5% molasses 2% urea

Feed intake (kg DM/day)

0.86

0.86

1.30

Nutritive value %


TDN

38.70

39.70

44.30


DP

0.00

0.07

3.77

Cost (LE/ton)


DM

38.7

39.7

44.3


TDN

97.3

96.7

92.3

* Adapted from Nour, 1986.
1 US$ = 0.70 LE

Fahmy et al (1968) reported that the presence of rice hulls in a diet improved the utilisation of feed constituents. The addition of sand to a diet high in concentrates stimulated better utilisation of the ration (Gooley and Burroughs 1962). The relatively high silica in rice hulls may have produced a similar effect in the experiments of Fahmy et al (1968) and in the present experiment.

The review of the results indicates that rice straw and rice hulls are deficient in protein, energy, and minerals and their nutritive values are quite low. Physical, chemical and microbiological methods have been investigated to improve the digestibility and nutritive value of these by-products. Supplementation with energy, protein, minerals and vitamins resulted in improving the utilisation of the roughages.

Table 8. Composition (%) of the feed mixtures used throughout the fattening experiment using diets containing rice hulls *

Ingredients

Mixture No

1

2

3

4

5

1. Composition %


Rice hulls

70

50

10

-

-


Cottonseed cake

-

8.5

22.5

24

48


Rice bran

-

-

12

10

7


Wheat bran

10

10

10

29

19


Yellow maize

10

20

38

29.5

20


Molasses

6

6

3

3

3


Urea

-

1.5

1.5

1.5

-


Calcium carbonate

3

3

2

2

2


Sodium chloride

1

1

1

1

1

2. Chemical analysis %


Dry matter % Dry matter

92.36

92.37

91.55

91.98

91.71


Crude protein

4.00

13.75

21.72

17.72

17.51


Crude fibre

39.48

24.54

13.61

11.41

16.98


Ether extract

12.92

4.65

7.42

5.87

5.12


Ash

14.47

11.77

9.32

8.79

7.98


Nitrogen free extract

38.13

45.29

51.68

56.19

52.41

* Source = Nour et al (1986).

Conclusion

It could be concluded that improving the utilisation of rice straw and rice hulls may be achieved through:

1. Pelleting of roughages after supplementation with concentrates (maize, molasses, rice or wheat bran, cottonseed cake) urea, minerals and vitamins to produce optimum complete diets suitable for feeding ruminants on large scale farms.

2. Ensiling of rice straw or rice hulls after urea treatment and mixing with berseem or any other legume forage - this method is recommendable to the small scale farms in Eygpt and perhaps elsewhere where rice straw and rice hulls are available.

Table 9. Growth rate and efficiency of feed utilisation in fattening cattle fed on the experimental diets indicated.





Period No.

A

B

Diet No.

Diet No.

I

II

III

I

II

III

Animal number

10

10

9

9

9

9

Experimental period (days)

91

91

91

63

63

63

Av. Initial weight (kg)

234.8

237.4

235.8

329

327.1

334.3

Av. Final weight (kg)

333.8

322

319.7

391.8

397.3

383.7

Liveweight gain (kg)

99

84.8

84.1

62.8

70.2

49.4

Av. daily gain (kg/day)

1.01

0.93

0.92

1.00

1.11

0.78

DM intake/day

3.92

4.74

3.89

3.29

3.31

3.34


a. roughage (kg/day)

8.53

8.24

8.09

7.07

7.37

7.31


b. concentrate (kg/day)

12.45

12.98

11.98

10.36

10.68

10.65

Feed efficiency:


kg DM intake/kg gain

12.33

13.96

13.02

10.36

9.62

13.65

Period A)

I. Rice straw plus mixture 5. in table 8
II. Mixture 1 plus mixture 5. in table 8
III. Rice straw plus mixture 3. in table 8

Period B)

I. Rice straw plus mixture 5. in table 8
II. Rice straw plus mixture 2 + mixture 5 in table 8
III. Rices straw plus mixture 4 in table 8

References

Abaza M.N., Nabawiya Hafiz, El-Torky M., Nour A.M., Borhami B.E., El-Shazly and Naga M.A. 1981. Effect of sodium hydroxide or steam treatments on nutritive value of poor quality roughages in vitro. Alexandria Journal of Agricultural Research. 29 (3): 1178-1188.

Abou Rya A.K., Abou Hussein E.R., Shalaby A.S. and Salem O.A. 1983. Nutritional and phsiological studies with short-time alkali treated roughages. Proc. Workshop. Appl. Res. Alexandria, 14-17 March 1983 pp 38-47.

Badr M.F. and Abou Akkada A.R. 1965. Rice hulls as a substitute for wheat straw in sheep feeding. Alexandria Journal of Agricultural Research. XIII (1): 1-10.

Bender F., Heaney D.P. and Bowdess A. 1970. Potential of steamed wood as a feed for ruminants. Forest Production Journal 20: 364.

Fahmy S.T., Badr M.F., Abou Akkada A.R. and El-Shazly K. 1968. The effect of replacing part or all of the wheat straw with ground rice hulls on the performance of lambs. Animal Production U.A.R. 8:1.

Fahmy S.T. 1985. The effect of alkali treatment on the feeding value of some roughages. Communications in Scientific & Developmental Research. (No. 79). 64-70.

Gooley J.R. and Burroughs W. 1982. Sand additions to high concentrate beef cattle rations. Journal of Animal Science 21: 991.

Heaney D.P. and Bender F. 1970. The feeding value of steamed Aspen for sheep. Forest Products Journal. 20: 98.

Jackson M.G. 1977. Review article: The alkali treatment of straws. Animal Feed Science and Technology. 2:105.

Jackson M.G. 1978. Treating straw for animal feeding. FAO Animal Production & Health Paper No. 10.

Mohsen M.K., Santiel G.E., Mahmoud S. and Basuni M.I. 1983. Fermentation characteristics and Nutritional value of corn cobs and rice straw ensiled with Monensin. Proceedings Workshop Applied Research, Alexandria. 14-17 March 1983. pp 104-114.

Nabaweya E., Abaza M.A., Nour A.M., El-Shazly K. and Naga M.A. 1983. The nutritive value of alkali treated rice straw for fattening lambs. Proceedings of Workshop on Applied Research, Alexandria. 14-17 March 1983. pp 115-121.

Nour A.M. and El-Shazly K. 1981. The nutritive value of pelleted rations containing rice hulls. Alexandria Journal of Agricultural Research. 29 (1): 35.

Nour A.M., Zahran S.M. and Naga M.A. 1987. Effect of different methods of sodium hydroxide treatment on nutritive value of rice straw. Alexandria Journal of Agricultural Research (in press).

Nour A.M. 1986. A simple method for utilisation of rice straw on the small scale farm in Egypt. ARNAB. Proc. Workshop, Alexandria, Egypt. October 1985. 72-78.

Shehata M.N. and Nour A.M. 1986. Rice straw in complete pelleted diets for sheep. Proc. ARNAB Workshop. Alexandria, Egypt. October 1985. 79-86.

Smith T., Balch C. and Broster W. 1983. Straw as a feed for growing cattle. Proceedings Workshop Applied Research, Alexandria. 14-17 March 1983. pp 165-170.

Torgrimsby J. 1971. Personal communication to Homb et al. (1977). (c.f., Jackson 1978).

Wilson R.K. and Pigden W.J. 1964. Effect of sodium hydroxide treatment on the utilisation of wheat straw and poplar (Populus alba) wood by rumen microorganisms. Canadian Journal of Animal Science. 44:122.


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