N. H. Sheikh
Department of Animal Production
Faculty of Agriculture, Somali National University
P.O. Box 801, Mogadishu, Somalia
Abstract
Introduction
Materials and methods
Results and discussion
Conclusion
References
A study to assess the susceptibility of banana crop residues (stems and leaves) to ensiling was undertaken in order to utilize this material during the dry season when feed is in short supply.
Four treatments of ensiling banana crop residues were examined: direct-cut silage (material with 90% of moisture); direct-cut silage treated with sugar-cane molasses at a rate of 5% of fresh weight; wilted (material with less than 70% of moisture); wilted and treated with molasses (5% of fresh weight).
The chemical composition of banana crop residues has shown material high in moisture content and low in water-soluble carbohydrate is not suitable to be ensiled without treatment prior to ensiling. Wilting to more than 30% DM and the addition of molasses gave a satisfactorily ensiled product.
In many tropical countries like Somalia, the main constraint aside from water is the lack of sufficient feed during the dry season. This fact hinders the development of the livestock sector in Somalia and makes the settlement of the nomads almost impossible.
Substantial amounts of agricultural by-products, such as banana and sugar-cane, are produced annually in Somalia. However, this forage is presently underutilized. The potential for by-product feeding in Somalia is great and its efficient utilization can contribute in large degree to the development of the Somalia livestock industry.
Fresh banana crop residues are already used as animal feed in some tropical countries (Johri and Shrivastava, 1967). However, a large portion of these crop residues are lost each year as a result of poor conservation methods.
The objective of this study was to determine the possibility of ensiling banana crop residues with or without additives in order to increase its utilization as animal feed throughout the year.
The banana crop residues used in this study were harvested from two year-old plants of the "Poyo" variety after the fruit was harvested. The plants were in good vegetative condition, under normal management practicies for production of banana fruits. The distance between rows and plants was 2 x 4 m, giving a plant density of 5000 per hectare. Before the material for ensiling was collected, representative samples of banana crop residues were taken to estimate the total mass of this material per unit area. About 50 plants were randomly removed. The whole plant as well as stems and leaves were weighed separately. The latter was done to determine the ratio between the two components. These operations were conducted in the field with a portable balance.
Since direct-cut banana crop residue has a very high moisture content (80-90%), it was proposed to evaluate the suitability of this material for ensiling alone as well as treated with additives. Molasses was used as an additive in this study, because it is a good source of soluble carbohydrate and is available in large quantities as a by-product of the sugar-cane industry, usually close to banana plantations.
The following four treatments were applied in this study:
1. Direct-cut silage (high moisture material 80-90%).2. Direct-cut silage treated with sugar-cane molasses
(5% of fresh weight).3. Wilted silage (more than 30% of DM).
4. Wilted silage treated with molasses (5% of fresh weight).
Initially the whole banana crop residues were cut manually and chopped into lengths of 2 cm or less in order to obtain well-packed material. The chopped materials of Treatments 3 and 4 were wilted prior to ensiling by laying them in the sun for about 8 hours until the moisture content was reduced to below 70%.
Four micro-silos each having a capacity of 100 kg of wet chopped material were uniformly filled with banana crop residues. The filling was done in layers, with each layer being tightly packed to reduce air space. During the packing operation molasses was uniformly spread on each layer of Treatments 2 and 4 at a rate of 5% on fresh weight basis.
All four silos were opened after 45 days, and a 2 kg sample from each silo was drawn for proximate analysis (AOAC 1974) and determination of pH. In addition other visual and olfactory tests such as colour and presence or absence of mould, and tests of acceptability to goats, were made.
The average weight of the whole banana plants after removal of the bunch was 28 kg, while the average weights of stems and leaves were 22.6 kg and 5.9 kg respectively, giving a ratio between them of 4:1, confirming the good vegetative condition of the plants and the excellent variety used in this study.
The total mass of crop residues per unit area is about 890 t/ha/year of fresh weight (around 89 t of DM/ha/year). Total area of banana plantations in production in Somalia is 4700 ha implying a potential annual yield of forage available for livestock use of over 4 million tons.
* Source: Somali Fruit Company, 1986.
The chemical compositions of banana stems and leaves are presented in Table 1, for material in this study and that of Johri and Shrivastava (1967). The data from the present study illustrate the high moisture content in both banana stems and leaves, particularly the former. Crude protein and ether extract were higher in leaves, while crude fibre and N-free extract were similar in both fraction. These data indicate that banana stems are less nutritious than leaves. The nutrient content of banana leaves indicates that this forage is much better than many tropical forages found in Somalia (Yanelli, 1984).
Table 1. Chemical composition of banana stems and leaves on a dry-matter basis (%) in this study and in that of Johri and Shrivastava (1967).
|
|
|
Stems |
Leaves |
|
Moisture |
% |
92.08 |
83.58 |
|
Crude protein |
% |
2.70 (2.4) |
8.50 (12.2) |
|
Ether extract |
% |
0.85 (2.3) |
3.55 (8.1) |
|
Crude fiber |
% |
30.05 (20.5) |
31.20 (25.0) |
|
N-free extract |
% |
46.60 (60.5) |
43.70 (38.9) |
|
Ash |
% |
19.80 (14.3) |
13.00 (15.8) |
|
Calcium |
% |
1.35 (1.16) |
1.04 (1.78) |
|
Phosphorus |
% |
0.44 (0.22) |
0.19 (0.14) |
The analyses from the four treatments, before and after ensiling are given in Table 2, and pH and other visual and olfactory evaluation such as colour, odour, and absence or presence of mould are given in Table 3.
Table 2. Chemical composition of banana crop residues (mixed stems) and leaves on dry-matter basis, before (1) and after (2) ensiling
|
|
Treatment |
||||||||
|
|
Direct-cut |
Direct-cut with molasses |
Wilted |
Wilted with molasses |
|||||
|
(1) |
(2) |
(1) |
(2) |
(1) |
(2) |
(1) |
(2) |
||
|
Crude protein |
% |
5.75 |
4.55 |
3.85 |
4.60 |
4.80 |
5.90 |
3.80 |
5.30 |
|
Ether extract |
% |
2.10 |
2.15 |
1.05 |
1.85 |
1.85 |
2.30 |
0.80 |
1.40 |
|
Crude fiber |
% |
31.70 |
35.50 |
18.95 |
31.50 |
29.20 |
32.15 |
18.30 |
29.20 |
|
N-free extract |
% |
41.85 |
39.50 |
54.75 |
42.55 |
36.00 |
37.80 |
58.50 |
42.60 |
|
Ash |
% |
18.60 |
18.45 |
21.40 |
19.40 |
28.15 |
21.85 |
18.60 |
21.50 |
|
Ca |
% |
2.32 |
2.38 |
1.66 |
2.55 |
2.13 |
2.73 |
1.77 |
2.44 |
|
P |
% |
0.16 |
0.10 |
0.10 |
0.09 |
0.11 |
0.11 |
0.09 |
0.10 |
Table 3. Physical and chemical characteristics of ensiled banana crop residues after 45 days.
|
Treatment
|
||||
|
Direct-cut |
Direct-cut with molasses |
Wilted |
Wilted with molasses |
|
|
Colour |
Dark brown |
Dark brown |
Dark brown |
Light brown |
|
Dry matter (%) |
12.95 |
11.03 |
32.80 |
31.46 |
|
pH |
5.8 |
5.4 |
6.1 |
4.1 |
|
Mould growth |
Yes |
Yes |
Yes |
No |
From visual observation the colour in Treatments 1, 2, and 3 were dark brown with unpleasant odour, probably due to the accumulation of butyric acid. The dark colour intensified following contact with air direct-cut silage was found to be unsuitable for ensiling because of its high moisture content and low content of soluble carbohydrate. For that reason the reduction of moisture and the addition of molasses could be considered an appropriate intervention to obtain a successful ensiling.
The pH of Treatments 1, 2 and 3 remained relatively high (5.8; 5.4; 6.1 respectively). The colour of Treatment 4 (wilted silage and treated with molasses) was light brown in colour with a pleasant odour of lactic acid. No visible mould growth was observed and the pH was lower (4.1).
When the ensiled materials were offered to goats ad libitum they refused to eat the silage from Treatments 1 and 2 where secondary fermentation was marked (unpleasant odour), but the materials from Treatments 3 and 4 were consumed.
There are large quantities of banana crop residues available in Somalia with substantial potential for contributing to its livestock industry. Even though this by-product alone is a poor quality feed, it becomes extremely important for maintenance purposes during the dry season when little or no grass is available.
From this experiment it was concluded that banana crop residues are likely to ferment successfully when the moisture content is reduced to below 70% prior to ensiling and a fermentable carbohydrate source such as molasses is added.
AOAC (Association of Official Analytical Chemists). 1974. Official methods of analysis. AOAC, Washington, D.C.
Bolsen, K.K, Ilg, H.J. and Axe, D.E. 1980. Additives for corn silage. J. Animal Sci. 51. Suppl. 1:230.
Johri, P.N. and Shrivastava, J.P. 1967. Indian Vet. J. 44: 425.
Yanelli, P. 1984. The principles of pasture improvement and range management and their application in Somalia. FAO,
Rome.
