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The current status of knowledge on the feed value of Crotalaria species

S.V. Sarwatt and F.E.J. Mkiwa

Department of Animal Science and Production
Faculty of Agriculture
Sokoine University of Agriculture
P.O. Box 3004, Morogoro, Tanzania


Introduction
Botanical description
Chemical composition
Utilisation as feed for livestock
Toxicity of Crotalaria spp.
Conclusion
References


Abstract

The potential of Crotalaria ochroleuca in farming systems in Tanzania is reviewed. Possibility of its use as a livestock feed is discussed in terms of its nutritive value in comparison to that of other legumes. However, there is no documented scientific information on its utilisation as a livestock feed in Tanzania. Factors that limit its wide utilisation as a feed are given. The paper suggests areas of research emphasising a multidisciplinary approach in attempting to appreciate the role of this wild legume in our agricultural systems.

Introduction

The potential and use of forage legumes in farming systems and particularly in livestock nutrition has been well summarised by Tothill (1986). However research on indigenous wild legumes has been very limited compared to improved legumes. Tropical legumes which are used for forage have been cultivated during the last 50 years (Williams, 1983) yet the volume of unexplored genetic resource remains vast.

Crotalaria ochroleuca locally known as "marejea" in Tanzania is a well-known leguminous plant in the southern part of the country. As early as 1939, the legume was cultivated on small scale by Benedictine Fathers at Peramiho (Rupper, in press). It was mainly cultivated for the purpose of restoring fertility to the soil and to combat weeds. During shortages of fodder the legume was fed to dairy cows and calves. Although no quantified data is available, the performances of the animals were observed to be good.

The aim of this paper is therefore to highlight research work related with Crotalaria spp. in the field of animal production. Areas that need immediate investigations are emphasised.

Botanical description

Crotalaria, the genus to which Crotalaria ochroleuca belongs is the largest in tropical Africa and is commonly encountered in open places from mountains to semi-deserts, with over 500 species (Polhill, 1982). Most of the species are either annuals, semi perennial, perennials, herbs or shrubs (Martin and Leonard 1970). The leaves are either simple or compound with 3, 5 or 7 leaflets (Polhill, 1982).

Most of the species have numerous yellow flowers which later on bear tough-skinned seed pods that are inflated (Polhill, 1982). The number of seeds contained in a single pod depends on species but ranges from 5 to 50 seeds. The seeds are kidney-shaped, and their colour varies from olive-green to either yellow-red or brown.

Chemical composition

Dry-Matter Yield

Total dry matter is one of the factors which to a large extent determines the carrying capacity of a forage. In many selection programmes dry-matter yield is a key criteria for selection (Whiteman, 1980). Since Crotalaria spp. are among the high nitrogen fixers, this partly explains their yield potential because total dry matter and nitrogen fixation in legumes are known to be positively correlated.

In Upper Volta, it has been reported that C. juncea produced 10 tonnes/ha of dry matter without application of fertilizer (Anon, 1965). In Surinam when C. quinquefolia was grown for fodder, Ubels (1960) recorded an average of 17 tonnes/ha of dry matter. In the southern part of Tanzania, Mukurasi (1986) harvested 12 tonnes/ha of dry matter from C. zanzibarica. Comparatively, lucerne (Medicago sativa), which is one of the most important perennial fodders used in many regions of the world produces yields of 8-9 tonnes/ha (Whiteman, 1980).

Crude Protein, Minerals and Other Nutrients

Table 1 shows that an average crude protein content of Crotalaria spp. ranges from 10-35% with a mean of 24.1%. Crude protein content of the whole plant of C. ochroleuca is 28.1% and that of leaves is 34.5%. Although it is not possible to rank tropical legumes in terms of their protein content, according to Minson (1977) the mean crude protein of tropical legumes is 17.2%. The range may lie between 5.6% for Stylosanthes humilis to 35.8% for Leucaena leucocephala. It is therefore obvious that Crotalaria ochroleuca ranks high amongst other legumes in terms of crude protein content (Table 2).

The crude fibre content of a forage is another important measure of dry-matter intake and in vivo dry-matter digestibility. The efficiency of ruminant microbes during digestion is influenced to a large extent by lignin available in the fibre component. Van Soest (1965) showed that the proportion of potentially digestible components decline as the fibrous content increases. Thus the relatively fair crude fibre content in Crotalaria (Table 1) suggests a possible high intake and dry-matter digestibility.

Phosphorus and calcium content in Crotalaria spp. has been shown in Table 1. According to NRC (1978) the minimum level of phosphorus requirements for most animals is about 0.15%, which is below the amount available in Crotalaria. The calcium content is observed to be fairly high compared to the other legumes.

Table 1. Chemical composition of different Crotalaria species.

Species

Stage of growth

DM

CP

CF

EE

NFE

Ash

Sika

Ca

P

Remarks

Author

C. anagyroides

Vegetative


23.00

28.02

2.17

39.59

7.22

0.07

0.57

0.28


Dougal & Bogdan (1936)

C. falcata

Early fl.


34.81

21.07

2.33

33.83

7.36

0.09

0.94

0.36


Dougal & Bogdan (1936)

C. incana

Vegetative


23.79

27.06

2.87

36.43

9.85

0.11

0.81

0.26


Dougal & Bogdan (1936)

C. intermedia

Early fl.


28.85

22.08

3.31

35.86

9.90

0.37

0.72

0.33


Dougal & Bogdan (1936)

C. intermedia

Full fl.


21.41

35.72

1.93

34.03

6.91

0.07

0.44

0.27


Dougal & Bogdan (1936)

C. mucronata

Full fl.


31.65

21.37

2.89

55.85

8.24

0.06

0.75

0.35


Dougal & Bogdan (1936)

C. paulina

Vegetative


18.40

27.01

2.68

41.32

10.59

0.53

1.15

0.29


Dougal & Bogdan (1936)

C. petitiana

Early fl.


20.32

32.75

2.18

37.16

7.55

0.14

0.82

0.32


Dougal & Bogdan (1936)

C. relusa

Early fl.


21.50

20.40

2.47

46.34

9.28

0.39

1.22

0.26


Dougal & Bogdan (1936)

C. vallicola

Full fl.


25.97

26.29

2.18

37.91

7.65

0.28

0.57

0.28


Dougal & Bogdan (1936)

C. recta



20.27

8.10

4.3

41.1

-





Dougal & Bogdan (1936)

C. juncea

-

-

24.95

31.62

2.81

27.62

13.00

-

1.47

0.36


Balaraman and Vankaterkrishman (1974)

C. zanzibarica

Full fl.


35.00

14.00

-

-

-



0.23


Mukurasi (1986)

C. spectabilis


20.86

10.00

41.70

1.38

40.03

6.89





Neal and Becker (1933)

C. striate


25.92

17.00

39.14

2.04

37.90

3.89





Neal and Becker (1933)

C. intermedia


25.00

12.04

41.00

1.64

40.08

5.24

-

-

-


Neal and Becker (1933)

C. quinquefolia


20.00

-

-

-

-

-

-

-

-


Ubels (1960)

C. incana


24.32

14.40

46.40

1.27

35.12

5.81

-

-

-


Neal and Becker (1933)

C. ochroleuca

Early fl.

-

34.50

14.26

2.93

34.43

8.57

-

0.80

0.35

Leaves

Sarwatt (1986)

C. ochroleuca

-


28.10

38.10

-

-

8.10

-

-

-

Whole plane

Sarwatt (1936)

MEAN

-

23.22

23.67

28.22

2.43

37.33

8.00

10.21

10.86

10.30



Table 2. Composition of nutritive value of different fodder legumes to Crotalaria (% DM basis).

Fodder

DM

CP

CF

EE

NFE

Ash

Ca

P

Author

Desmodium uncinata

-

23

8

-

-

-

-


Dougal & Bogdan (1936)

Desmodium uncinata

-

13

38.8

-

-

-

-

-

Milford (1967)

Stylosanthes humilis

-

14

-

-

-

-

-

-

Newman (1968)

Medicago sativa

-

21.2

29.4

1.4

35.1

9.1

-


Reddy (1969)

Leucaena leucocephala

-

25.9

12.4

-

-

11.0

2.36

0.23


Leucaena leucocephala

-

20

21

6.4

49.26

11.2

2.2


Skerman (1977)

Crotalaria juncea

-

18.1

38.1

1.1

34.1

7.8

1.4

0.25

Reddy (1969)

C. ochroleuca

18.4

35.0

12.9

-

-

8.3

-

-

Sarwatt (1986)

C. ochroleuca

-

14.0

-

-

-

-

-


Mukurasi (1986)

Utilisation as feed for livestock

Research on the use of Crotalaria as a feed for livestock is very limited. The limited data that is available does not give quantitative investigations to establish the potential of Crotalaria spp. as a fodder plant. The only work that gives some detail is that of Balaraman and Vankaterkrishman (1974) who determined the nutritive value of C. juncea by conducting a metabolism trial using rams. The chemical composition and digestibility coefficients of sunnhemp hay used is shown in Table 3. Intake on average was 2.57 kg of dry matter per 100 kg body weight. The digestibility coefficients on consumption basis showed that the portion consumed was highly digestible. However, on feed basis the digestibility coefficients were very poor due to the fact that the rams chose the leafier parts of the plant and rejected the stems.

Table 3. Chemical composition and digestibility coefficients of C. juncea fed to sheep (% of DM).

Nutrients

Composition

Consumption basis

Feed basis

Dry matter

-

61.90

31.49

Organic matter

-

65.07

32.50

Crude protein

24.95

75.88

19.95

Crude fibre

31.65

59.53

53.68

Other extracts

2.81

35.62

24.39

NFE

27.62

57.30

27.51

Ash

13 00

-

-

Calcium

1 47

-

-

Phosphorus

0.36

-

-

Source: Balaraman and Vankaterkrishman (1974).

Toxicity of Crotalaria spp.

About 20 species of Crotalaria in tropical Africa alone are known to cause poisoning to cattle (Polhill, 1982). The symptoms seem to vary but common syndromes include inflammation of the horn, lameness and occasional starvation due to refusal by the animals to eat The more lethal forms of poisoning affects the nervous systems; lungs and liver (Polhill, 1982). Poisoning seems to be serious at flowering and seed stages. Probably this is due to accumulation of the toxic alkaloid substance called Crotaline in these parts of the plant at maturity. Steyn and van de Walt (1945) reported loss of wool when sheep were fed C. juncea hay that was cut at flowering stage. They suggested that supplementation level in livestock feeds should not exceed 10% of the daily ration. Rupper (1984) observed that when C. ochroleuca seeds are sprinkled between the bags containing cereal grains, storage pests were killed instantly. They reappear six to nine months later. The fact that Crotalaria spp. have been observed to be toxic in one location but non-toxic in another, may explain the contradicting reports. The reasons why one species can be toxic in one location and non-toxic in another is still not yet understood. Crotalaria ochroleuca may be poisonous at flowering stage and the seeds may contain some poison, however, the legume seems to be non-toxic before flowering (Rupper, 1984). Further research on this area is needed to establish the effect of feeding the legume on livestock performance and health.

Conclusion

Crotalaria ochroleuca is regarded as a multi-purpose crop in agricultural production in Tanzania. Its importance as a livestock feed has been underscored because the plant is cultivated mainly in the area where a small number of livestock are kept and the land is not a limiting factor (Sarwatt, in press). In areas where cultivable land is a problem (e.g. in Arusha and Kilimanjaro regions) the legumes can be intercropped with regular food or cash crops.

The legume will provide nitrogen to the crops intercropped with and assist in the control of weeds and nematodes. The green part can be cut two to three times and fed to livestock. Every time the legume is cut, the nodules senescent thus releasing more nitrogen and other nutrients which can be utilised by the accompanying crops.

Research on the multi-purpose use of "marejea" is very limited in Tanzania. Most of the information available is mainly from the farmers' experience, which fails to answer questions like "how much N is fixed by marejea under the present farming system," or "how much marejea should be fed to a dairy cow for efficient milk production". For these questions to be answered, a multi-disciplinary approach is needed. Lack of scientific information on its feed value as regards feed intake, digestibility coefficients and safe levels of supplementation calls for an urgent need to assess the animal production potential of this plant as a cheap fodder legume.

References

Anon. 1965. La crotalaire, legumineuse fourragere annuelle possible en region Mossi. (Crotalaria, a possible annual fodder crop for the Mossi area). Cah. Agr. Pratique Pays Chands 2. Tropical Abstracts 21:93-95.

Balaraman, N. and Vankaterkrishman, R. 1974. Nutritive value of sunnhemp (Crotalaria juncea Linn) hay for sheep. Indian Veterinary Journal 51(5):337-341.

Dougal, H.W. and Bogdan, A.V. 1936. The chemical composition of some leguminous plants grown in the herbage nursery at Kitale, Kenya. East African Journal of Agriculture and Forestry 32(1):45-49.

Martin, J.H. and Leonard, W.H. 1970. Principles of field crop production. Macmillan Co., New York.

Milford, R. 1967. Nutritive value and chemical composition of seven tropical legumes and lucerne grown in sub-tropical south eastern Queensland. Australian Journal of Experimental Agriculture and Animal Husbandry 7:540-545.

Minson, D.J. 1977. Chemical composition and nutritive value of tropical legumes. In: D.J. Skerman (ed.), Tropical forage legumes. FAO, Rome.

Mukurasi, N.J. 1986. Agricultural attributes of Crotalaria zanzibaries. Uyole Agric. Centre, Mbeya, Tanzania.

NAS. 1979. Tropical forage legumes. Natural Academy of Sciences, Washington, D.C.

Neal, W.N. and Becker, R.B. 1933. A type of laboratory silo and its use with Crotalaria. Journal of Agricultural Research 47:617-625.

Newman, D.M.R. 1968. A comparison of the nutritional value of Stylosanthes humilis, S. guyanensis and introduced grass in Northern Rhodesia. Australian Journal of Agricultural Research 28:921-935.

NRC (National Requirements Council). 1978. Nutrient requirements of domestic animals. Nutrient requirements of dairy cattle. 5th edition. National Academy of Sciences, Washington, D.C.

Polhill, R.M. 1982. Crotalaria in Africa and Madagascar. A.A. Balkema Co., Rotterdam.

Reddy, M.R. 1969. Sunnhemp hay can cut down concentrate needs of cattle. Indian Farming 18:45-46.

Rupper, G. P. 1984. Marejea Rafiki ya Wakulima. Benedictine Pub. Ndanda - Peramiho.

Rupper, G.P. (in press). Cultivation of Crotalaria ochroleuca around Peramiho. In: Proc. of Marejea cultivation in Tanzania held at Peramiho, Songea, 15th-21st October, 1986.

Sarwatt, S.V. 1986. Chemical composition and in vitro dry matter digestibility of Crotalaria ochroleuca. Dept. of Animal Science, Sokoine Univ. of Agriculture, Tanzania.

Sarwatt, S.V. (in press). The value of Crotalaria ochroleuca as a livestock feed. Proc. of Marejea cultivation in Tanzania held at Peramiho, Songea, 15th-21st October, 1986.

Skerman, P.J. 1977. Lablab purpureus (L) Sweet. In: Tropical forage legumes. FAO Plant Production and Protection Series, No. 2. FAO, Rome.

Steyn, D.G. and van der Walt, S.J. 1945. Farming in South Africa 20:445-447.

Tothill, J.C. 1986. The role of legumes in farming systems of sub-Saharan Africa. In: I. Haque, S. Jutzi and P.J.H. Neate (eds), Potentials of forage legumes in farming systems of sub-Saharan Africa. Proceedings of a workshop held at ILCA Addis Ababa, Ethiopia, 16-19 September 1985. ILCA, Addis Ababa, Ethiopia.

Ubels, E.R. 1960. Green manuring. Herb. Abst. 31(1):144.

Van Soest, P.J. 1965. Symposium on factors influencing voluntary intake of herbage by ruminants. Voluntary intake in relation to chemical composition and digestibility. Journal of Animal Science 24:834-843.

Whiteman, P.C. 1980. Tropical pasture science. Oxford University Press, London.

Williams, R.J. 1983. Tropical legumes. In: J.G. McIvor and R.A. Bray (eds), Genetic resources of forage plants. CSIRO, Melbourne, Victoria, Australia.


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