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The potential of crop residues, particularly wheat straw, as livestock feed in Ethiopia

Lulseged Gebrehiwot and Jamal Mohammed
Institute of Agricultural Research
P.O. Box 2003, Addis Ababa, Ethiopia


Abstract
Introduction
Conclusion
Acknowledgements
References


Abstract

Crop and livestock production are important activities in the smallholder mixed farming systems in Ethiopia. Feed resources for livestock are natural herbage and crop residues. Cereal straws of teff (Eragrostis tef), barley, wheat and pulse crop residues are very important particularly during the dry season. Currently crop residues are used as is with no treatment to improve intake and digestibility. The quality and quantity of residues produced is also very low in relation to the total area of cropped land.

Results of experiments clearly indicate that the yield and quality of crop residues could be tremendously improved through agronomic practices and varietal selection. Undersowing of wheat with forage crops did not reduce grain yield but resulted in reasonable production of straw and undersown forages which could improve intake and digestibility of the residue. In the wheat improvement programme, significant variations were found among the varieties with respect to grain yield, straw yield and quality. There seems to be a wide range of possibilities to improve the production and utilisation of wheat straws, and crop residues in general. Breeders and agronomists need to consider the residue aspect as part of the overall crop improvement programme.

Introduction

Ethiopia is an agricultural country with a diverse climate varying from cool tropical highlands to arid lowlands. Though low in productivity it has the highest number of livestock in sub-Saharan Africa. Among other factors, feed shortage, both in quantity and quality, is a major constraint for the development of the livestock industry in Ethiopia.

At present two broad categories of livestock production systems are recognised in the country. In the pastoral areas, which are characterised by low and erratic rainfall, livestock are mainly kept for milk and to some extent for meat. They provide the sole means of subsistence for the nomadic pastoralists. It is estimated that some 25% of the total Ethiopian livestock population is found in this region. These animals depend entirely on the natural vegetation to satisfy their nutritional requirements.

The highlands of Ethiopia have more favourable climate; both for crop and livestock production. Over 70% of the human as well as the livestock population reside in this region. Small holder mixed farming is the dominant mode of production in the Ethiopian highlands. Major food crops grown are teff (Eragrostis tef), barley, wheat and pulses; and in the warmer regions maize and sorghum. The most important contribution of livestock to agricultural production in the Ethiopian highlands is the use of oxen for cultivation. Crops and livestock are closely integrated throughout the highlands in a complex of competitive and complementary ways (Gryseels and Anderson, 1983).

Livestock in the highland peasant farming system get their feed from natural herbage and crop residues. Cereal straws of teff, barley, wheat and pulse crop residues are stacked after threshing and fed to selected group of animals during the dry season. Livestock also have access to crop stubbles and weedy fallows. It is estimated that crop residues and aftermath grazing contribute 10% of the annual feed demand (FAO, 1981).

Crop residues have long been important as a maintenance feed for ruminants. However, when used alone, they are of very low feeding value with poor metabolisable energy, negligible available protein, and seriously deficient in mineral and vitamins (Staniforth, 1979). On the other hand, crop residues vary greatly in chemical composition and digestibility depending on varietal differences (Reed et al, 1986) and agronomic practices (Staniforth, 1979). Their feeding value and intake can also be greatly improved through treatments and supplementation with protein and energy-rich feeds (Butterworth et al, 1986, Olayiwole et al, 1986).

Developing countries like Ethiopia need to seriously consider improving the quantity and quality of crop residues produced by the smallholders. Varietal effects on the quantity and nutritive value of cereal and pulse crop residues have not received enough attention. Understandably because the major efforts have been on increasing food production only. These programmes should consider the residues as part of the overall improvement programmes.

This paper attempts to review the extent and use of crop residues in Ethiopia; mainly in the highlands. It places special emphasis on wheat with respect to varietal differences and agronomic practices to enhance the utilisation of the straws.

Extent of crop production and available residue

Estimates of the Ethiopian Central Statistics Office show that during the period of 1975 to 1978, on the average, annually about 5 million hectares of land were put under cereals and pulses. Mean grain yield for the same period was 970 kg and 810 kg/ha for creels and pulses respectively. However, during the period 1979 to 1982, the total area cultivated for cereals and pulses increased to 5.6 million hectares (Central Statistical Office, 1984). Respective grain yields also increased to 1240 kg 1140 kg/ha (Table 1).

As the area of crop production is increased, the size of grazing areas dwindles, exacerbating the problem of feed shortage. In this situation one could only cope with the problem by improving the quantity and quality of crop residues produced. FAO estimates indicate that in 1979/80, Ethiopia as a whole produced about 6.3 million tonnes of cereal straws, stovers and pulse residues (FAO, 1981). The figure seems to be low when compared with the total acreage under production. However, there are still wide options to improve total production .

Table 1. Estimated area and yield of major crops in Ethiopia.

Major Crops

1975/76 to 78/79
(4 years mean)

1979/80 to 82/83
(4 years mean)

hectares

kg/ha

hectares

kg/ha

Teff

1,368,500

750

1,401,600

920

Barley

722,800

980

864,800

1220

Wheat

522,300

960

605,400

1140

Maize

791,200

1360

769,600

1700

Sorghum

753,500

1000

1,013,800

1490

Faba bean

277,900

1020

340,600

1490

Field peas

121,900

650

176,300

950

Haricot beans

33,300

780

26,900

910

Cereals total

4,420,300

970

4,848,300

1240

Pulses total

643,000

810

795,300

1140

Source: Central Statistical Office (1975 to 1983).

Variability of crop residues in yield and quality

The quantity and quality of residues produced by various crops vary greatly depending on crop species. Wheat and barley usually give high straw yields but of inferior quality. Among the cereals teff straw is relatively the best and is comparable to a good natural pasture hay. Pulses residues, though low in yield, are of high quality (Table 2). The quality and yield of the various crop residues shown in Table 2 could vary depending on agronomic practices and environmental conditions. However, the figures give good indications of the relative importance of the various crop residues.

Table 2. Yield and chemical composition of various crop residues on dry-matter basis.

Residue type

Percent

Yield
kg/ha

DM

EE

Ash

CP

NDF

Barley straw

10,000

92.6

2.3

8.4

4.7

71.5

Teff straw

5000

92.6

1.9

8.4

5.2

72.6

Wheat straw

9000

93.1

1.2

9.0

3.9

79.8

Faba bean residue

3800

91.7

0.8

10.4

7.2

74.3

Field peas residue

5000

91.9

1.2

6.1

6.7

73.6

Natural pasture hay

4100

92.2

1.5

9.5

6.6

73.8

DM = dry matter; CP = crude protein;
EE = ether extract; NDF = neutral-detergent fiber.

The performance of animals on residue diets is also known to vary depending on crop species. Table 3 shows the weight gains of steers fed for 116 days a ration composed of 50% residue, 20% molasses, 25% noug cake (Guizotia abyssinica), 4% bone meal and 1% salt (JAR, 1976). As shown in Table 3 wheat straw was the poorest roughage and teff straw the best. Dry-matter intake and daily weight gain were lowest for wheat straw, 5.0 kg and 352 gm/head respectively.

Table 3. Weight gains of steers fed crop residue based diets * at Holetta (1974/75) for 116 days.


Parameters considered

Roughage source

Teff
straw

Whea
straw

Oats
hay

Native
hay

Initial weight (kg)

186

185

182

184.3

Final weight (kg)

258.8

225.9

231.9

239.6

Daily gain (g)

628

352

430

477

Daily feed intake (kg)

6.9

5

5.5

5.9

Feed/kg liveweight gain (kg)

11

14.2

12.8

12.4

* Rations consisted of 50% crop residue, 20% molasses, 25% noug cake, 4% bone meal and 1% salt. Source: IAR (1976).

Possibilities for improving the yield, quality and utilisation of wheat straw

a) Agronomic practices

The grain yield of cereals and pulses is highly influenced by various agronomic practices. Since high grain yield is usually a function of active vegetative growth, agronomic practices which aim at increasing grain yields, do result in higher yields of residue.

A fertiliser trial was carried out on irrigated wheat in the Awash Valley, a fertile alluvial soil. Though the various rates of nitrogen fertilisation had very little effect on grain production (Table 4), straw yield and quality were significantly improved. Applying 46 kg N/ha improved leaf-to-stem ratio, and % N in the leaves and stems by 20, 47 and 21% respectively over the control. With more N application there was more influence on leaf-to-stem ratio and N composition of the plant. In Ethiopia, farmers who harvest good grain crops usually have more residues to feed their cattle during the dry season. Nowadays farmers are encouraged to use fertilisers, especially in areas where rainfall is more reliable. This practice will hopefully result in more crop residues and grain yields.

b) Undersowing of forage crops to wheat

Studies by the Institute of Agricultural Research in Ethiopia show that forage crops could be successfully established under cereals. The effect of the undersown forage crops on the grain yield of the cereals varied depending on crop species and the level of weed management. When maize was undersown after second weeding (about six weeks after planting) the grain yield was not affected at all. But in the case of wheat, where the forage crops were sown at the same time with the wheat the grain yield was reduced by about 20% (Lulseged et al, 1987).

Table 4. Effect of N fertilization on grain yield and on quantity and quality of wheat straw in the Awash Valley.

Fertilizer rate

Mean for 1985 and 1986

Grain yield

Straw yield

Leaf/stem
ratio

%N
leaves

%N
stems

N kg/ha

kg/ha

0

3500

7900

0.83

0.38

0.17

46

3800

8600

1.00

0.46

0.25

69

3800

9100

1.02

0.57

0.30

92

4200

9200

1.07

0.63

0.34

115

4300

10400

1.16

0.65

0.34

LSD (0.05); NS 1.0 t/ha

The practice of undersowing cereals with forages has particular relevance in the highlands of Ethiopia where fallowing of cropped-land is common and feed shortage is a serious problem. Table 5 shows results of an experiment at Holetta where wheat was undersown with various forage crops. The difference in grain yield of the wheat for the various treatments was non-significant. The yield on the control plot (sole crop of wheat) should probably have been higher than the undersown plots. But because of excessive lodging the yield was even lower than the other treatments.

Table 5. The performance of wheat and undersown forage crops at Holetta (1982/83).

Undersown forage species

Wheat grain yield

Wheat straw yield (air dry)

Forage yield (dry matter)

kg/ha

kg/ha

Control (wheat only)

2040

7900


Phalaris tuberosa cv Sirocco

2630

9800

3100

Lolium perenne cv Kangaroo Valley

3410

11400

3500

Lolium perenne cv Mt. Alma

2330

8200

7000

Lolium perenne cv Barspectra

2760

7600

4000

Festuca arundinacea

3100

11500

1300

Setaria sphacelata cv Narok

2560

9000

1900

CV%

17.8

19.8

15

LSD (0.05)

NS

NS

800 kg/ha

The most interesting part of this experiment was that on the average 9400 kg/ha of wheat straw and 3400 kg/ha of improved forages could be harvested from the same piece of land. Similar experiments in Ginchi area (Vertisol, 2200 m elevation) also showed various grasses and legumes could be successfully established under wheat (Table 6) (JAR, 1982).

ILCA's investigations on farmers' fields at Holetta indicated that undersowing native clovers namely Trifolium tembense and T. rueppellianum with 30 kg P/ha significantly improved both wheat grain and straw yields. The increase over the control (wheat alone) was 22 and 29% for grain and straw yields respectively (Abate and Jutzi, 1985). Undoubtedly the quality of the straw would be improved tremendously due to the presence of the forage species, particularly the legumes. Various investigators have reported that the digestibility and intake of crop residues alone are very low and weight gains of animals are minimal (O'Donovan, 1979; Reed et al, 1986). However, when supplemented with improved forages, particularly legumes, intake, digestibility and weight gains improved. Hence, wherever the environmental and farming system conditions permit, undersowing should be encouraged.

Table 6. Forage crops undersown to wheat, Ginchi, 1980/81.

Treatment

Wheat yield
(kg/ha)

Forage establishment
Score 0-5

Forage yield
(kg/ha)

Sole crop (control)

2930

-

-

Alfalfa

2850

2

700

Barrel medic

3090

4

3200

Snail medic

2840

3

2100

Phalaris

3060

2

200

Llolium

1960

5

2600

Tall fescue

2900

2

700

Setaria

2790

2

400

CV

19%


0 = poor

LSD (0.05)

NS


5 = Excellent

c) The need to select for better grain and straw yielding varieties

Classically, the objective of any crop improvement programme is to raise the level of grain yields, with no consideration to straw yield and quality. Under small peasant holding, however, both the grains and straws are important. In Ethiopia over 90% of the agricultural produce comes from the peasant sector. Therefore in order to improve overall farm productivity and income of the smallholders, development of crop varieties with improved grain as well as straw yields is of paramount importance.

In the wheat improvement programme for irrigated lowlands, the selected varieties have been examined for grain yield as well as straw yield and quality. Fourteen varieties have been tested for three years in the Awash Valley. Of these, eight gave grain yields of over 4000 kg/ha. Some of the high-yielding varieties had low straw yields. Considering both grain and straw yields the varieties PAI 4, Dashen, Gara and Chenab 70 were the best with straw yields of 6300 to 7500 kg/ha (Table 7). Though there were other varieties with straw yields of nearly 8000 kg/ha, their grain yield was very low. The varieties also showed great variability with respect to leaf-stem ratio and % N in the leaves. Considering all these factors together, Chenab 70 and Dashen seem to be the best in terms of both grain and straw yield and quality.

Conclusion

In the Ethiopian highlands crop and livestock production are complementary. Since most of the livestock in the highlands are mainly kept for draught, the cultivation of more land results in more crop residues to feed the work oxen and selected group of animals. However, currently the quantity and quality of residues produced are very low.

Therefore inorder to compensate for the grazing land, which has been converted into crop land, agronomic practices and crop improvement programmes need to consider the improvement of both grain and straw yields and quality. Since there are strong crop improvement programmes of the major cereals and pulses in Ethiopia, there is a great chance of achieving success. The utilisation of crop residues also needs to be enhanced through the use of forage legumes and protein/energy-rich industrial by-products.

Table 7. Grain yield, straw yield and quality of wheat varieties tested in the Awash Valley (1985 to 1987).



Grain yield
(3 yrs mean)

Straw yield
(2 yrs mean)

Leaf-to-stem
ratio

% N
leaves

% N
stems

kg/ha

MLKS 11

4300

5700

0.83

0.68

0.29

PAI 4

4200

6300

0.78

0.56

0.22

Dashen

4000

6900

1.08

0.79

0.32

Blue Jay 'S'

4200

5400

0.79

0.54

0.25

CM 5287-N-2M

3600

5300

0.61

0.74

0.33

CM 30136-3Y-1Y

3500

5300

0.78

0.68

-

Gara

4200

7500

0.91

0.57

0.32

Quimori

3800

6100

0.65

0.65

0.24

Chenab 70

4400

7200

0.77

0.83

0.28

Galld-4R-Resel (B)

4200

5900

0.85

0.64

0.30

Monco x WW x LEE

4100

5600

0.96

0.66

0.29

Gall-YR-Resel (B)

3700

7800

0.95

0.61

0.24

Enkoy

3700

7800

0.68

0.58

0.35

Ani 'S' Cm 26346

3600

5800

0.50

0.59

0.24

CV%

15

20




LSD (0.05)

0.7

1.5




Acknowledgements

We are very grateful to Ato Addisse Nuramo and Ato Seyoum Bediye for running the chemical analysis of the feed samples.

References

Abate Tedla and Jutzi, S. 1985. Results of a cereal forage legume intercropping trial on smallholder farms in the Ethiopian highlands. Highlands Programme Report. International Livestock Centre for Africa (ILCA), Addis Ababa.

Butterworth, M.H. and Mosi, A.K. 1986. The voluntary intake and digestibility of combinations of cereal crop residues and legume hay for sheep. ILCA Bulletin 24: 1417. International Livestock Centre for Africa, Addis Ababa.

Central Statistical Office. 1984. Results of agricultural sample surveys. 1974 to 1978 and 1979 to 1984. Government of Ethiopia. Addis Ababa, Ethiopia.

FAO. 1981. International scheme for the co-ordination of Dairy Development and International Meat Development Scheme. Report of a Mission to Ethiopia, 27 May - 28 June, 1980. FAO, Rome.

Gryseels, G. and Anderson, F.M., 1983. Research on-farm and livestock productivity in the central Ethiopian highlands: Initial results, 1977 - 1980. ILCA Research Report No. 4. International Livestock Centre for Africa, Addis Ababa.

IAR (Institute of Agricultural Research). 1982. Animal Science Forage and Range Management Department Progress Report. April 1980 to March 1981. Addis Ababa, Ethiopia. pp. 73-76.

IAR (Institute of Agricultural Research). 1976. Results of experiments in animal production. 1966/67 to 1975. Animal Production Report No. 1. Institute of Agricultural Research, Addis Ababa. p. 42.

Lulseged, G.; Gebremedhin, H. and Taddesse, T. 1987. Undersowing of forage crops in cereals: Some achievements. Proceedings of the First National Livestock Improvement Conference, Addis Ababa, February 11 to 13, 1987. Institute of Agricultural Research, Addis Ababa, Ethiopia.

O'Donovan, P.B. 1979. Fattening crossbred and Zebu cattle on local feeds and by-products in Ethiopia. World Animal Review 30: 23 - 29. (FAO, Rome.)

Olayiwole, M.B.; Butterworth, M.H.; Sayers, A.R. and Olorunju, S.A.S. 1986. The effect of supplementing cereal straws with urea, Trifolium hay and noug meal on feed intake and liveweight gain of growing crossbred heifers. ILCA Bulletin No. 24: 18-20. International Livestock Centre for Africa, Addis Ababa. pp. 18-20.

Reed, J.D.; Abate Tedla and Jutzi, S. 1986. Large differences in digestibility of crop residues from sorghum varieties. ILCA Newsletter vol 5, no. 1.

Staniforth, A.R. 1979. Cereal straw. Clarendon Press, Oxford, Great Britain.


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