Introduction of fodder crops in rural areas of Burundi

H. Banzira

Institut des Sciences Agronomiques du Burundi (ISABU)
B.P. 795, Bujumbura, Burundi

Introduction
Conclusion
References

Introduction

The problem of feeding livestock is particularly acute during the dry season. There are several alternative solutions, namely improving natural pastures (division into paddocks, rotation of grazing lands, control of fires, and mowing), use of agricultural pastures byproducts, and introduction of improved pastures. The traditional system does not include forage production and is wholly dependent on natural pastures of Eragrostis and Hyparrhenia. These natural pastures supply adequate feeds in the rainy seasons but are inadequate in the dry seasons. Research has been undertaken in Burundi to test improved pasture species.

To achieve this goal many grass species have been introduced in the various centres and research stations of the Institute of Agricultural Research (ISABU - IAR). Among those tested, the most promising are Tripsacum laxum, Pennisetum purpureum, Setaria splendida and Setaria sphacelata which gives a good yield of high feed value. Consequently these have been selected for introduction into the rural areas. However, the introduction of these forage crops in Kigozi and Mahwa areas is combined with the introduction of Sahiwal x Ankole heifers/cows. The use of improved cattle is important to ensure economic returns to investments in fodder production. The choice of the two areas is based on their proximity to the two research stations and it is therefore easy to visit and advise the farmers.

At the moment, this study will focus on the productivity of these fodder crops under intensive cultivation and on their impact on animal and food production.

Characteristics of the Recommended Grasses

Tripsacum laxum is recommended in the agricultural zones situated between the 750 m (at Lake Tanganyika level) and 1,700 m in altitude. It is planted up to 2,000 m, however, it is excellent for dry-season feeding as it does not become stemmy and has a good leaf-stem ratio.

Pennisetum purpureum grows at altitudes ranging from sea level up to 2,000 m receiving between 1,000 to 15,000 mm of rain on rich soils. It grows in areas where any crop can grow. Setaria splendida and S. sphacelata grows at high altitudes (1,700 to 2,400 m) while Setaria sphacelata grows at altitudes of 700-1,700 m. They require rainfall of more than 600 mm in some areas per year. At altitudes above 1700 m of Mugamba and Bututsi. Setaria grows where Tripsacum cannot thrive. Setaria is also used to control soil erosion when planted on contours.

Type of Usage

The four grasses are sub-grouped in accordance with their suitability for grazing. T. laxum and P. purpureum are used in a cut-and-carry system while Setaria sphacelata and S. splendida can be either grazed or cut and carried.

The Establishment of the Pastures

Soil Preparation

For the four grasses it is recommended to plough deeply to a depth of 3 cm irrespective of the type of implements. With hand cultivation it is advised to bury the organic matter under the soil. If tractors are available it is recommended to harrow. The application of manure at 40 tons per ha before planting has been found to be beneficial. Annual applications at 10-15 tons of manure per ha at the onset of the rains in October is also recommended.

Results

The production of green matter in intensive farming

The productivity rates (total green matter per hectare from two harvests per year) presented in the graphs below were obtained with a large input of artificial fertilizers and organic manure.

Forage Production

Generally, elephant grass produces more green fodder in a four-year cycle than Guatemala grass (170 and 130 t/ha in Mugamba, 150 and 120 t/ha in Bututsi, 240 and 185 t/ha in the Eastern Savannas as well as 180 and 130 t/ha in Imbo and Lower Ruzizi, respectively). Estimates of dry-matter yield can be made based on dry-matter content of the fresh material.

Table 1. Production of T. laxum, P. purpureum and S. splendida in the three regions according to the different cutting intervals (green matter/ha)

Cutting interval (months)	T. laxum		P. purpureum			S. splendida
	Mugamba	But.	Moso	Mugamba	But.	Moso	Mugamba
2	-	-	116.7	-	-	186.7	-
3	131.5	111.3	-	167.3	137.3	-	121.4
4	142.7	124.2	169.0	187.3	128.7	272.0	111.7
6	172.2	155.6	219.0	194.0	156.7	268.1	115.3

Setaria splendida produced similar amounts of green matter to that of the T. laxum in four years at high altitudes (140 t/ha in Mugamba and 120 t/ha in Bututsi). In all the regions of Burundi the distribution of the annual harvests shows that the production of T. laxum is similar during the first four years of farming. The production of T. purpureum, on the contrary, decreased drastically in the course of the four-year period in Imbo and Bututsi region. In the same ecological zones, Setaria splendida yielded constantly for the first three first years followed by a sharp drop in the fourth year.

In conclusion we can say that the most productive grass for cutting is P. purpureum, but its decreasing production of forage with time makes it imperative to re-plant at shorter intervals in order to increase its productivity. This constraint does not apply to T. laxum.

With regard to the two species of Setaria, they can be grown for cutting for the three years and thereafter, their good resistance to grazing makes them adaptable to grazing management.

Leaf-stem Ratio

The leaf-stem-ratio was calculated for the plants at the ideal harvest stage - plants aged two to three months for Setaria and four months for T. laxum and the P. purpureum.

The ratios were 9.6 for the T. laxum, 0.5 for elephant grass, 2.25 for S. splendida and 2.50 for S. sphacelata. We note straight away the extremely high ratio of the Guatemala grass and the very low ratio for P. purpureum. The ratio for the two Setaria is similar with an intermediate value. Based on this we can assume that T. laxum is of good quality followed by Setaria.

The Food Value

Chemical analyses have been carried out on the grasses harvested at high altitude (Bututsi). Cutting was done every 2-3 months, four months or six months (Table 2). Dry-matter content varied between 22 and 29%. There is little difference between regions. However, the T. laxum seems to have slightly higher rates of dry matter than the other two grasses. T. laxum has a higher protein content and a higher energy value than the elephant grass, but the reverse is the case for cellulose content and mineral elements (Ca, P, Na and Mg). The changes in the content of mineral and organic substances are similar in the two fodder crops for cutting. There is, however, a reduction in the amounts of protein K, Ca and P, as well as an increase in the cellulose content, when the cutting is done frequently. It appears then that the mowing should be done every three to four months in order to maintain a high forage value of the harvested grass.

With regard to the graminaceae for mowing and for pasture the highest protein content is observed in frequent cuttings and the highest rate of cellulose is also observed when the cutting is done at the time of flowering. This suggests that these two grasses must be harvested before they flower in order to ensure that they are of high food value.

Table 2. Dry-matter content of grasses at various stations (%)

Cutting interval (months)	T. laxum			P. purpureum			S. splendida
	Bututsi	Mug.	Moso	Bututsi	Mug.	Moso	Mugamba
2 or 3	26.0	29.1	27.4	22.5	26.2	24.5	24.5
4	27.5	27.8	28.4	22.7	27.4	27.2	26.9
6	28.6	27.3	29.1	26.4	27.3	27.6	22.4

Studies on chemical composition have been made at Bututsi. The results are shown in Table 3. Seasonal variations are most significant in protein contents of elephant grass. Mineral contents are generally low with the exception of potassium.

Table 3. Changes in average organic matter content (% of dry matter) and mineral elements (Mg/kg of dry matter) during the dry rain seasons

Elements		Tripsacum laxum		Pennisetum purpureum
		Rainy season	Dry season	Rainy season	Dry season
Cellulose		33.2	34.4	37.2	37.0
Crude protein		13.0	9.3	10.3	2.2
	Ca	2.340	2.206	2.700	2.971
	P	1.698	1.680	1.854	2.038
	K	20.281	16.413	19.237	17.847
	Na	112	92	102	280
	Mg	1.379	1.667	1.365	1.509

The evolution of the contents of the various elements between the dry and rainy season is similar for the two species: an increase in cellulose and Mg, a decrease in proteins and K, and little change in the concentration of Ca and P. The differences already noted for the two grasses with regard to average annual content are reflected in the seasonal rates. It can also be noted that whatever the season, T. laxum has less cellulose than P. purpureum.

Changes in the dry matter were marked between the two seasons (Table 4) as was to be expected.

The analysis of the general production levels obtained by the different cutting systems (Table 1) reveals the superiority of cuttings practiced more than twice a year: the four-monthly system being in between while cuttings carried out every two or three years turn out to be the least productive. A three monthly cutting rhythm is best for S. splendida.

A comparison of these results with those of the chemical analysis shows that a four-monthly cutting rhythm is the system which guarantees satisfactory production of high quality mowing grass, while for Setaria, the three-monthly rhythm gives the best results.

Table 4. Changes in percentage dry matter

	Tripsacum laxum		Pennisetum purpureum		S. splendida
	Dry season	Rainy season	Dry season	Rainy season	Dry season	Rainy season
Mugamba	30.9	24.9	30.1	22.7	27.8	20.5
Bututsi	29.6	25.1	26.5	20.9	-	-
Moso	28.9	26.8	26.7	24.7	-	-

Ensiling

The only preservation method which is practiced in Burundi is ensilage. The usual loss in green matter is in the region of 25 to 30%. However, prior drying of the grass, which reduces the water content by 10%, limits the loss in weight to 15%.

The extension of forage crops in the rural areas

The extension of fodder crops is done in the same way as the extension of other plants through the regional development projects and societies as well as through the new research project by ISABU (Institute of Agricultural Research - Burundi). The objective is to transfer modern agro-pastoral techniques to the rural areas. ISABU produces the planting material and crossbred Sahiwal heifers for introduction into the rural areas. Farmers are advised to plant the grasses in accordance with the research findings, but it is obvious that farmers do not have all the required inputs, in particular adequate manure. Fields of the forages are lower than on station. In the future it is planned to introduce a legume such as Desmodium intortum in the system.

Conclusion

The poor quality of Burundi soils and the ever-worsening deterioration of the pastures calls for an intensification of fodder crop cultivation. However, even if the intensification of forage crop cultivation remains the basic component of the improvement of animal feeding, certain constraints hinder such vital action, especially:

1. The arable area being quite small, the area allocated to fodder crops will be reduced in favour of food crops.

2. These fodder crops need manure, but priority in the use of manure will go to the food crops before anything else.

3. Extension methods are not yet sufficiently developed to sensitize peasants to the advantages of fodder crops, and this accounts for the persistence of transhumance.

The project undertaken by ISABU with the aim of changing the present extensive method of livestock production in the rural areas into a semi-intensive one through the introduction of fodder crops and improved cattle may result in the improvement of the environment, more livestock productivity, and better nutrition of the rural population.

References

ISABU Annual Reports. (1963-1981). Vancoppenole, R. 1984. Ecologie, phytotechnique, productivite et valeur alimentaire de quatre graminees fourrageres au Burundi: Tripsacum laxum Nash, Pennisetum purpureum Schumach, Setaria splendida Stape et Setaria sphacelata (Schum) Stape et Hubbard. ISABU Publication No. 49.