M.A. Kabatange and A.J. Kitalyi
Livestock Production Research Institute
P/Bag Mpwapwa, Tanzania
Abstract
Introduction
Methodology
Results and discussion
Conclusion
Acknowledgements
References
The importance of crop residues in ruminant nutrition in the long dry seasons of semi-arid areas need not be overemphasised. In this paper the existing practices of cereal crop residue feeding of livestock in Central Tanzania is discussed. The physical limitations to its use are highlighted. Production characteristics and nutritive values of three most common cereals in the area are presented.
Stover dry matter (DM) yields of bulrush millet, sorghum and maize were 9661±1343.0, 8244±1491.5 and 7222±479.8 kg/ha respectively. Crude protein (CP) ranged from 3.7 to 5.4 per cent for the different stover fractions at harvesting and from 3.1 to 4.4 per cent at mid-dry season. In vitro organic-matter digestibility (IOMD) was 52.6 to 68.3 per cent at harvesting and 46.5 to 63.5 at mid-dry season. Between harvesting and mid-dry season, DM, CP and IOMD of the crop residues declined by 63%, 0.6% and 4.8 per cent respectively. These figures show that both yield and nutritive value are reduced if the residue is left standing in the field after grain harvest. Possible improvement strategies on crop residue utilisation are suggested.
Central Tanzania lies between latitude 4° and 7°S and longitude 33° and 37°E. It covers an area of about 140,000 km² in the central semiarid plateau at an elevation of 750-1500 m above sea level. The mean annual rainfall ranges from 400-800 mm with high variation in amount and distribution. The inhabitants are mainly agro-pastoralists cultivating millets, sorghum, maize and groundnuts as principal crops. Livestock species kept are cattle, sheep, goats and donkeys.
Utilisation of cereal crop residues for livestock feeding, though of major importance in the agropastoral system, has not been fully exploited. The ruminant population depends on natural grasslands for feed, particularly in the wet season.
Crop residues form an important feed component in the dry season. In a project "Improvement of Animal Production Systems in Central Tanzania" a study to evaluate the potential value and constraints to utilisation of crop residues for livestock feeding was initiated.
Following the Farming Systems Research (FSR) approach, a diagnostic survey was carried out from June 1985 to May 1986 (Annual Report 1985/86). In the various stages of the diagnostic survey carried out, guidelines followed and questions set in the formal survey aimed at understanding the existing use and management of crop residues. In the following cropping season (1986/87), crop residue production and utilisation was monitored.
Crop residues of the most commonly grown cereals, bulrush millet, sorghum and maize were harvested from selected farmer fields in Berege and Majeseni villages. Two samplings were carried out, the first one at grain harvest, in early June and the second one at mid-dry season, in early September. Plant density and grain yield were estimated from 100 m² plots, whereas stover yield, stalk and leaf fractions were estimated from 4 m² quadrats. Dry matter (DM), crude protein (CP) and in vitro organic-matter digestibility (IOMD) were determined on the stover fractions.
Table 1 shows farmer responses on use of crop residues for livestock feeding. Use of legume haulms for livestock feeding was negligible. The haulms, mainly groundnut, are produced in the wet season when pasture availability is not critical, and there are practical limitations to their conservation for dry season feeding. Grazing in the crop fields after grain harvest was the most common method of availing the crop residues to livestock (61%, n = 152), though some farmers indicated not to allow animals to graze in the crop fields after harvest. A higher proportion of farmers in the maize zone gave the latter response, alleging that the practice led to reduced grain yields in subsequent crops. None of the respondents indicated that they collect or conserve the residues for later use. Efficient utilisation of the crop residues is limited by the following factors; big herd sizes, long distances from crop fields to kraals/homesteads (4.6 km), lack of transport and low level of technology.
Table 1. Use of crop residues for livestock feeding in the study area (per cent of responses).
|
Village |
n |
Cereal stovers |
Legume haulms |
|
Banyibanyi |
17 |
59 |
20 |
|
Majeseni |
12 |
25 |
0 |
|
Lenjulu |
20 |
55 |
0 |
|
Mlembule |
15 |
40 |
0 |
|
Berege |
20 |
40 |
47 |
|
Nghambi |
17 |
59 |
47 |
|
Kinusi |
16 |
31 |
0 |
|
Kisima |
17 |
12 |
0 |
|
Chamtumile |
18 |
50 |
11 |
|
Study area |
152 |
41 |
9 |
Source : Annual Report (1985/86).
There were wide variations in plant height and density which may be attributed to differences in soil fertility, seed quality, variety and husbandry practices followed. Farmers in the same area were not following uniform recommended crop husbandry practices as exemplified in observations whereby farmers put 7-30 sorghum seeds per planting. This usually resulted in more vegetative growth and low grain yields (Table 2).
Table 2. Grain and stover yields and harvesting indices of bulrush millet, sorghum and maize (kg/ha).
|
Type of cereal |
Sorghum |
Bulrush millet |
Maize |
|
Grain yield |
578 ± 174.5 |
690 ± 339.2 |
3633 ± 437.9 |
|
Stover yield at grain harvest |
8244 ± 1491.5 |
9661 ± 1343.0 |
7222 ± 479.8 |
|
Harvesting index (%) |
7 |
7 |
50 |
|
Stover quantity at mid-dry season |
3206 ± 895.5 |
1579 ± 527.3 |
4029 ± 766.7 |
|
Utilisation (%) |
61 |
84 44 |
|
Variations in grain and stover component yields were high for all the crops studied. The quantities of millet and sorghum crop residues were high compared to other reported values and the corresponding harvesting indices were relatively low (Annual Report, 1983/84; Powell, 1986). This may be due to the practice of planting many seeds resulting into more vegetative growth. High variations in stover yields are common in traditional farms due to differences in management practices. Values ranging from 0.6 to 10 tons/ha have been reported (Annual Report, 1983/84). Loss in stover during the mid-dry season was high, particularly with millet and sorghum stover. The higher loss in these crops could be due to exposure to grazing on these fields than in the maize fields. It had been noted earlier that some farmers, particularly those in the maize growing zone, did not allow livestock into their fields. However, figures on utilisation are to be taken with caution because not all crop residue loss was due to grazing. Losses due to wind shatter and by termites might have been substantial but were not measured. Further investigation to quantify such losses is needed.
Crude protein and digestibility of crop residues are important indicators of their nutritive value and these are summarised in Table 3.
The cereal crop residues investigated showed that CP values ranged from 3.7 to 5.4 per cent at harvesting and from 3.1 to 4.4 per cent at mid-dry season. In both periods the protein content was marginal-to-deficient and not adequate for ruminal microbial breakdown of ingested forage. Values obtained for CP are lower compared to a study carried out in Botswana (Annual Report, 1983/84) probably because there was no fertiliser use in this area. The IOMD values were high for the leaf fractions compared to the stalk or whole stover. Similar trends have been observed by other workers (Powell, 1986; Annual Report, 1983/84). Maize stovers had the highest IOMD followed by sorghum and millet in decreasing order. A decline in crude protein content and digestibility of the stover fractions as the dry season advanced was noted. In general there was a decline of 0.6 and 4.8 per cent in CP and IOMD, respectively.
Table 3. Crude protein and IOMD of bulrush millet, sorghum and maize stover fractions.
|
Crop residue |
At harvesting |
At mid-dry |
season |
|
|
CP% |
IOMD% |
CP% |
IOMD% |
|
|
Sorghum whole stover |
5.0 |
60.3 |
3.8 |
52.7 |
|
Sorghum stalk |
3.7 |
56.6 |
4.2 |
54.1 |
|
Sorghum leaf |
5.4 |
62.8 |
4.4 |
58.5 |
|
Bulrush millet whole stover |
4.4 |
56.0 |
4.0 |
48.3 |
|
Bulrush millet stalk |
4.4 |
52.6 |
3.6 |
46.5 |
|
Bulrush millet leaf |
4.5 |
63.2 |
4.3 |
54.1 |
|
Maize whole stover |
3.9 |
63.2 |
3.1 |
60.4 |
|
Maize stalk |
4.3 |
60.0 |
3.9 |
58.9 |
|
Maize leaf |
5.0 |
68.3 |
3.6 |
63.5 |
The information gathered from the diagnostic survey and the study clearly shows that there is underutilization and inefficient use of the crop residues. Further, there is need for development of technological packages on proper use of this feed resource. Harvesting and transporting crop residues to homesteads/kraals would be very difficult because the materials are bulky. There is therefore a need for introducing economical harvesting, collection, handling, transportation and storage methods.
On improvement of the quality of crop residues, introduction of forage legumes in the feeding system would be the most practical. Under stall-feeding practices value of various forage legumes such as Leucaena, Stylosanthes, and Trifolium species in improving the nutritive value of crop residues have been tested (Mohamed-Saleem, 1985; Butterworth, 1986). Inclusion of a grain legume such as Dolichos lablab and pigeon pea in the cereal fields for grazing with crop residues after grain harvest is another possibility.
The authors wish to acknowledge the International Development Research Centre, Canada for sponsoring them to this workshop. Permission to attend the workshop granted by the Director General TALIRO (Tanzanian Livestock Research Organization) is highly appreciated. Finally we wish to express our sincere thanks to Mr. J. Sanga for the assistance in field work, Mr. R.A. Mwassa for the laboratory work, Mr. R. Chibindu for typing the manuscript and colleagues at LPRI, Mpwapwa for assistance rendered in the course of preparing this paper.
Annual Report, 1983/64. Livestock and Range Research in Botswana, Animal Production Research Unit; Gaborone, Botswana.
Annual Report, 1985/86. Livestock Production Systems (Tanzania) Project No. 3-P-64-0076 IDRC/TALIRO.
Butterworth, M.H. and Mosi, A.K. 1986. The voluntary intake and digestibility of cereal crop residues and legume hay for sheep. ILCA Bulletin No. 24-March 1986. ILCA, Addis Ababa.
Mohamed-Saleem, M.A. 1985. Effect of sowing time on the grain yield and fodder potential of sorghum undersown with Stylo in the subhumid zone of Nigeria. Tropical Agriculture 62 (2): 151.
Powell, J.M. 1986. Crop-livestock interactions in the subhumid zone of Nigeria. In: R. Von Kaufmann, S Chater and R. Blench (eds), Livestock systems research in Nigeria's subhumid zone. Proceedings of the Second ILCA/NAPRI Symposium held in Kaduna, Nigeria, 29 October - 2 November 1984. ILCA, Addis Ababa, Ethiopia.
