Chemical composition and nutritive value
Feeding potentials of residues and animal performance
Conclusion
Bibliography
E.A. AdebowaleThe author is Head of the Livestock Unit, Institute of Agricultural Research and Training, Obafemi Awolowo University, PMB 5029, Ibadan, Nigeria.
In Nigeria, maize (Zea mays) is one of the most important cereal crops grown mainly for human consumption (Table 1). The estimated total grain yield amounts to 1.37 million tonnes per year, with an annual growth of 10.2 percent (FMAWR, 1988). The demand for maize exceeds the supply as a result of its additional use in livestock feed, baking and brewing industries.
Maize residues were estimated to be about 4.11 million tonnes in 1989, consisting mainly of straw, husks, skins and trimmings, cobs and bran. These residues, which often are either burned or ploughed into the soil, account for almost 25 percent of the total feed energy suitable for ruminant livestock. Maize is harvested twice a year in the rain forest zone of southern Nigeria, although a large proportion of the ruminant population that could utilize the residues is in the northern part of the country. Maize residues may be relatively poor in nutritive value compared with some other locally available residues or roughages (Dzowela, 1987), but wide availability, large quantities, easy and cheap procurement and large cellulose and hemicellulose reserves enhance their utilization as energy sources in ruminant feed. However, the high lignocellulosic content of the residues requires a source of readily available carbohydrates and nitrogen to optimize their utilization (Kategile, 1981), particularly when treated.
This paper highlights the nutritive characteristics of maize residues and the production feeding potentials for the most promising diets.
Studies were conducted to assess the nutritive value of maize crop residues for the purpose of developing feeding packages for farmers. Assessments were made for both chemically treated and untreated residues. The chemically treated residues were soaked in an 8-percent solution of organic waste ash (cocoa pod husk) for 16 hours and, without washing, were then sun-dried for about three days before feeding (Adebowale, 1985a; Adebowale, Orskov and Shand, 1991).
1 Estimates of production and residues of some food crops in Nigeria, 1987
Estimations de la production et des résidus de certaines cultures vivrières au Nigéria, 1987
Estimaciones de la producción de algunos cultivos alimentarios en Nigeria y de sus residuos 1987
|
|
Production |
Annual growth |
Residues |
|
(million tonnes) |
|||
|
Cassava |
11.63 |
6.8 |
1.74 |
|
Sorghum |
5.52 |
6.7 |
10.61 |
|
Yam |
5.24 |
0.0 |
0.94 |
|
Millet |
4.16 |
5.7 |
12.48 |
|
Leafy vegetables |
4.16- |
6.1 |
1.55 |
|
Citrus |
1.83 |
5.1 |
9.12 |
|
Maize |
1.37 |
10.2 |
4.11 |
|
Plantain |
1.15 |
4.5 |
0.23 |
|
Sugar cane |
0.89 |
34.9 |
- |
|
Pepper |
0.72 |
4.5 |
0.22 |
|
Cowpea |
0.76 |
5.0 |
- |
|
Rice |
0.29 |
27.4 |
0.58 |
|
Wheat |
0.04 |
118.5 |
- |
|
Soybean |
0.10 |
25.0 |
0.11 |
Source: FMAWR, 1988.
- = not estimated.
2 Chemical composition and nutritive value of treated and-untreated maize residues
Composition chimique et valeur nutritive des résidus de maïs traités et non traités
Composición química y valor nutritivo de los residuos de maíz tratados y no tratados
|
|
Chemical composition (%) |
(a +b)%1 |
(c)%/h |
||||||
|
CP2 |
NDF |
ADF |
ADL |
ASH |
Sheep |
Goats |
Sheep |
Goats |
|
|
Stover |
|||||||||
|
Untreated |
4.3g |
74.6e |
69.6d |
6.6e |
5.8e |
69.9de |
68.5de |
4,9e |
4.9ef |
|
Treated3 |
3.9g |
60.0f |
44.7e |
5.8e |
8.4d |
72.2de |
73.4de |
5.1e |
5.2e |
|
Husk |
|||||||||
|
Untreated |
5.8f |
62.5f |
45.7de |
4.5f |
2.7gh |
74.3d |
75.4d |
4.2f |
4.5f |
|
Treated |
4.1g |
41.8g |
44.5de |
3.8g |
4.8e |
78.9d |
81.1d |
4.1f |
4.9ef |
|
Cob |
|||||||||
|
Untreated |
2.4h |
86.1d |
44.8e |
8.6d |
1.9h |
54.0f |
53.8f |
2.5g |
2.8g |
|
Treated |
1.9f |
63.5f |
50.2d |
4.8f |
3.7f |
63.6e |
64.5e |
2.9g |
3.1g |
|
Bran |
|||||||||
|
Untreated |
10.2d |
63.5f |
38.5f |
4.1fg |
2.2h |
82.8d |
80.5d |
6.5d |
5.9e |
|
Treated |
8.4e |
39.4g |
36.1f |
2.2h |
4.1ef |
88.5d |
86.8d |
7.2d |
7.1d |
1 Potential degradability: a, b and c values are constants in the equation, p = a+b (1-e-ct) where p is degradation at time t (Orskov and McDonald, 1979).
2 CP = crude protein; NDF = neutral detergent fibre, ADF = acid detergent fibre; ADL = acid detergent lignin.
3 Residues treated with 8 percent organic waste ash (Adebowale, Orskov and Shand, 1991).
d, e, f, g, h Means in the same column not having common letters differ significantly (P<0.05).
3 Intake and live-weight changes of young goats fed untreated or urea-treated maize residues in addition to browsing
Ration et modification du poids vif de jeunes caprins auxquels on donne outre le brout, des résidus de mats non traités ou traités à l'urée
Cambios en el consumo y el peso vivo de cabras jóvenes mantenidas en ramoneo y suplementadas con residuos de maíz no tratados o tratados con urea
|
|
Stover |
Husk |
||
|
Untreated |
Urea-treated |
Untreated |
Urea-treated |
|
|
Intake (kg/day) |
0.28c |
0.41b |
0.40b |
0.58a |
|
Live-weight change (g/day) |
- 15d |
+ 34b |
+ 12c |
+ 51a |
a, b, c, d Means in the same row not having common letters differ significantly (P<0.05).
4 Chemical composition of some potential supplements to maize residues
Composition chimique de certains compléments potentiels des résidus de mats
Composición química de algunos suplementos alimenticios de raciones que contienen residuos del maíz
|
|
|
|
Leaves |
||
|
Cassava |
Gliricidia |
Leucaena |
|||
|
(percentage) |
|||||
|
Dry matter |
23.5 |
18.4 |
21.1 |
25.0 |
30.0 |
|
Crude protein |
22.6 |
9.2 |
17.8 |
14.7 |
22.0 |
|
Crude fibre |
14.5 |
10.1 |
14.8 |
19.9 |
19.6 |
|
Ash |
11.7 |
9.8 |
6.3 |
4.7 |
4.4 |
|
Cell wall |
24.6 |
18.7 |
29.5 |
31.5 |
31.2 |
The nutritive evaluation of the residues was carried out by incubating treated or untreated residues in nylon bags in the rumens of fistulated West African Djallonke sheep and goats for periods of 8, 16, 24, 48, 72 and 96 hours (Mehrez and Orskov, 1977). Table 2 shows the chemical composition and nutritive value of the treated and untreated maize residues. Results showed that bran has the highest nutritive value and cob the lowest, with husk and stover somewhere in between. Potential- degradability of bran was between 83 and 89 percent and the degradation rate was between 6 and 7 percent per hour. This compares with 54 to 65 percent potential degradability and an approximate degradation rate of 3 percent per hour for maize cobs. For the treatment, crude protein, neutral detergent fibre and acid detergent lignin were solubilized, improving the potential degradability and degradation rate of all residues (Adebowale, Orskov and Shand, 1991). These chemical composition and nutritive values have been known to be affected by, among other factors, variety and tanning content, stage of harvest, length of storage, portion of leaf-to-stem selected, fertilizer application and soil fertility, plant diseases, weathering and maturity (Adebowale, 1988). The untreated residues were characterized by low nitrogen content and high cell-wall components with little soluble cell contents. When such residues are fed to ruminants, the structural polysaccharides (which comprise the carbohydrate fraction) are only partially degraded by rumen microorganisms. This results in slow and low digestibility, a low proportional fermentation pattern in the rumen and a negligible amount of fermentable and bypass protein, severely limiting the value of the unmodified straw as a feed component. For this reason, utilization may have to depend on supplementation or treatment or a combination of both.
Chemically treated maize residues
The nutritive value of residues may be upgraded by treating them in some way. Treatment may be physical (soaking, grinding, pelleting, boiling, steaming under pressure or gamma irradiation), chemical (sodium hydroxide, organic waste ash, alkaline hydrogen peroxide or urea/ammonia), physico-chemical (particle size/chemicals, NaOH/pelleting or chemical/steaming) or biological (enzyme, white rot fungi or mushrooms). The most pragmatic and acceptable is chemical treatment. This treatment (particularly with alkali) disrupts the cell wall by solubilizing hemicellulose, lignin and silica, hydrolysing uronic acid and acetic acid esters and swelling cellulose (Jackson, 1977). However, this system is only acceptable if the value of the response is higher than the associated costs of processing and treatment. The most utilized of the alkalis is caustic soda. The use of this alkali is not feasible in Nigeria, however, since it has to be imported at high costs and is not easily available to local farmers. When available, it is so caustic that farmers face the constant danger of chemical burns. A local substitute that continues to have wide acceptability is organic waste ash (Adebowale, 1985b).
As can be seen in Table 2, the potential degradability improved for all maize residues when chemically treated with alkali. According to Chesson (1981), alkali treatment maximizes plant structure damage by promoting microbial colonization, and prevents or slows down the rate of lignin accumulation on cell-wall surfaces by the specific degradation- of lignin or by the promotion of its solubilization. This solubilization appears to be the result of the cleavage of the specific alkali-labile linkage formed between the structural polysaccharides (hemicellulose) of the cell wall and lignin itself (Hartley, 1985). On a pragmatic basis, the use of organic waste ash (palm bunch or cocoa pod husk) (Adebowale, 1985b) or urea (Sundstol, Coxworth and Mowat, 1978) is recommended for smallholder livestock farmers. One of the difficulties of using urea is making it acceptable to domestic animals. This could easily be resolved by exposing the animals to the treated straw over a long period. It was found that treated maize residues must be supplemented or animals must be allowed to browse (Table 3) if they are to perform satisfactorily (Adebowale, 1988). This conclusion is also supported by Singh and Jackson (1971).
Supplementation of untreated maize residues
Supplementation is perhaps a cheaper and simpler way of feeding maize residues in situ, involving practical methods that are realistic of small farm situations, although French (1943) suggested that in situ grazing may be wasteful and inefficient. Since maize residues are low in nitrogen, one way of improving their nutritive value is to feed them to animals together with a variety of forage supplements that are potentially valuable to ruminants (Dzowela, 1987; Adebowale, 1988). Some of these forages include Siam weed (Eupatorium oduratum), cassava leaves (Manihot esculenta), Gliricidia leaves (G. septum), Leucaena leucocephala foliages and aquatic macrophyte (Eupatorium stagnina). Their chemical compositions are given in Table 4. Except for the aquatic macrophyte, the forages are fairly high in protein content. The beneficial effects of feeding these forages to ruminant animals include increased metabolizable energy and nitrogen intake, improved palatability, increased available minerals and vitamins, better rumen function and a laxative influence on the alimentary system.
In one feeding trial, 20 White Fulani steers were fed ad libitum on treated and untreated maize cobs (chopped) with fresh Siam weed (2 kg/head/day). Live weight improved from a daily loss of 320 g, when animals were fed untreated maize cobs, to a daily gain of about 480 g, when cobs were treated and supplemented with Siam weed (Table 5). In fact, animals on untreated maize cobs were taken off the experiment within three weeks because of weight loss. Even when cobs were treated but not supplemented, steers still lost weight. In another trial (Table 6), maize husk and bran supplemented with Leucaena foliage were fed to West African Djallonke goats for 12 weeks. Animals reacted better to maize bran than to maize husks. This confirms the earlier results (Table 2), which showed that maize bran is better degraded in the rumen than maize husks. However, these two maize residues are either expensive or cumbersome to procure, especially for feeding large animals.
5 Effect of supplementing treated or untreated maize cob diets with or without Siam weed (Eupatorium oduratum) on fattening steers
Effets sur l'engraissement des bouvillons de la complémentation de régimes d'épis de maïs traités ou non traités avec ou sans Eupatorium oduratum
Efecto de la suplementación con o sin Eupatorium oduratum de la dicta a base de mazorcas de maíz tratadas o no tratadas de terneros castrados de engorde
|
|
Maize cob diets |
|||
|
Untreated |
Treated |
|||
|
Without |
With |
Without |
With |
|
|
Siam weed |
Siam weed |
Siam weed |
Siam weed |
|
|
Dry matter intake (kg/day) |
3.8b |
5.9a |
4.1b |
6.0a |
|
Dry matter digestibility (%) |
38.0b |
41.0b |
43.0b |
50.0a |
|
Nitrogen retention (g/d) |
-3.8c |
+7.0b |
-4.0c |
+16.0a |
|
Live-weight gain (g/d) |
-320.0d |
+100.0b |
-110.0c |
+480.0a |
a,b,c,d Means in the same row not having common letters differ significantly (P<0.05).
In comparing maize residues with other crop residues, Alhassan (1985) fed Maradi goats with various cereal or legume residues and found that dry matter intake (DMI) ranged from 0.7 percent of body weight for maize stover to 2 percent for sorghum leaves, while legume crop residues intake ranged from 0.8 percent for cowpea vines to 3.4 percent for groundnut haulms. When feeding maize residues was compared with other cereal or legume crops, it was found that live-weight gain compared favourably (Table 7). Highest feed consumption was recorded for the maize residue, although this was not significantly higher than the sugar-cane tops. However, this high consumption did not produce better live-weight gain, except with sorghum stalks.
Supplementation of treated maize residues
Based on farmers' preference for wet rather than dry treated residues, an experiment was conducted in which the performances of mature heifers on both diets were compared. Diets were fortified with cottonseed cake, molasses and mineral supplements. All animals were fed an additional 1 kg of Panicum maximum per head/day. DMI increased from 86 g/W0.75 kg/day for dry treated maize cobs to 123 for wet treated maize stover (Table 8). Both DMI and live-weight gain indicated better utilization when wet straw was fed rather than dry residues. This study showed that wet diets were better than dry ones by between 11.5 percent (maize cobs) and 23 percent (maize stover) in terms of live-weight gain. Farmers claim that feeding wet treated materials is cheaper and less time-consuming. In an earlier study, Singh and Jackson (1971) found that while the intake of digestible organic matter increased by 25 percent for treated wheat straw (dried) over the untreated, the increase was 63 percent for the wet ration. When Gliricidia foliage was supplemented to about 15 percent of the DMI of White Fulani cows in a diet of maize husk, the milk yield increased by about 22.5 percent (Table 9). However, when maize husk was ensiled with 6 percent Urea for ten days, the milk yield increased by 42 percent with Gliricidia foliage and 29 percent without it.
The above results indicate that maize residues are potentially valuable feed resources for ruminants. For efficient utilization, supplementation with green forage or browse plants, or readily available carbohydrates such as cassava tops or peels, is essential for good production results. Supplementation may be carried out in addition to chemical treatment. Further work is required to investigate other plant species that could enhance the nutritive value of the residues, as well as to look into the mode of action of green forages in order to stimulate intake and production. +
6 Response of goats to the supplementation of maize husk or bran with Leucaena foliage
Réponse des caprins à la complémentation des spathes ou du son de mats par des feuillages de Leucaena
Respuesta de las cabras a la suplementación de las espatas o el salvado de maíz con follaje de Leucaena
|
|
Treatments |
|||
|
a |
b |
c |
d |
|
|
Maize husk |
50 |
- |
50 |
- |
|
Maize bran |
- |
50 |
- |
50 |
|
Leucaena foliage |
25 |
30 |
20 |
25 |
|
Groundnut cake |
15 |
10 |
20 |
15 |
|
Brewers wet grains |
10 |
10 |
10 |
10 |
|
Live-weight gain (g/day) |
65c |
80ab |
75b |
87a |
a, b, c Means in the same row not having common letters differ significantly (P<0.05).
7 Intake and response of goats to some crop residues supplemented with forage leaves
Ration et réaction des caprins à certains résidus végétaux complétés par des feuilles fourragères
Consumo y respuesta de las cabras a algunos residuos de cultivos suplementados con hojas de árboles forrajeros
|
|
Treatments |
|||
|
a |
b |
c |
d |
|
|
Maize stalk |
135 |
- |
- |
- |
|
Sorghum stalk |
- |
- |
- |
135 |
|
Sugar-cane tops |
- |
136 |
|
|
|
Panicum maximum |
- |
- |
136 |
|
|
Cowpea vines |
16 |
190 |
150 |
150 |
|
Cassava tops |
136 |
144 |
147 |
150 |
|
Digestible crude protein (g) |
1.2 |
1.0 |
1.1 |
0.8 |
|
TDN intake/g body weight gain |
6.2 |
5.1 |
5.8 |
4.2 |
|
Feed consumption (g/W0.75 kg) |
78.5a |
74.8ab |
67.3b |
42.5c |
|
Live-weight gain (g/day) |
56.3a |
55.0a |
50.0a |
40.0b |
1 Dry matter consumption (g day/goat).
a, b, c Means in the same row not having common letter differ significantly (P<0.05).
8 Chemical composition of wet or dry treated maize residues supplemented with molasses and the effect on dry matter intake and daily gains of Muturu heifers
Composition chimique de résidus de mats traités, humides ou secs, complétés par de la mélasse, et effets sur l'apport en matière sèche et les gains journaliers des génisses Muturu
Influencia de la composición química de los residuos de maíz tratados, húmedos o secos, suplementados con melaza, sobre el consumo de materia seca y el aumento diario de peso vivo de novillos Muturu
|
|
Diets |
|||
|
1 |
2 |
3 |
4 |
|
|
(percentage) |
||||
|
Maize stover (dry)1 |
69 |
- |
- |
- |
|
Maize stover (wet)2 |
- |
69 |
- |
- |
|
Maize cobs (dry) |
- |
- |
69 |
- |
|
Maize cobs (wet) |
- |
- |
- |
69 |
|
Cottonseed cake |
20 |
20 |
20 |
20 |
|
Molasses |
10 |
10 |
10 |
10 |
|
Mineral/vitamin |
1 |
1 |
1 |
1 |
|
Dry matter (g/W0.75 kg) |
98b |
123a |
86c |
119ab |
|
Live-weight gain (g/day) |
280c |
350a |
260d |
290b |
1 Residues were sun-dried to between 85 and 90% dry matter.
2 Residues were fed immediately after treatment.
a, b, c, d Means in the same row not having common letters differ significantly (P<0.5).
9 Daily milk yield of White Fulani cows fed urea-treated or untreated maize husk with-or without Gliricidia foliage supplementation
Rendement laitier journalier des vaches blanches Fulani nourries avec des spathes de maïs traitées à l'urée ou non traitées avec ou sans compléments de feuillages de Gliricidia
Producción diaria de leche de vacas Fulani blancas alimentadas con espatas de maíz tratadas con urea o no tratadas, y con o sin suplementación de follaje de Gliricidia
|
|
Untreated |
Urea-treated |
||
|
Without |
With |
Without |
With |
|
|
Gliricidia |
Gliricidia |
Gliricidia |
Gliricidia |
|
|
foliage |
foliage |
foliage |
foliage |
|
|
Milk yield (kg) |
3.1d |
3.8c |
4.0bc |
4.4a |
1 All cows received 1.5-kg concentrate ration per day and Gliricidia septum foliage formed approximately 15 percent (untreated maize husk) or 10 percent (treated maize husk) of dietary dry matter intake.
a, b, c, d Means in the same row not having common letters differ significantly (P<0.05).
Adebowale, E.A. 1985a. Organic waste ash as possible source of alkali for animal feed treatment. Anim. Feed Sci. Technol., 13: 237-248.
Adebowale, E.A. 1985b. Response of sheep and goats fed maize straw treated with local alkali. Niger. J. Anim. Prod., 12: 137-140.
Adebowale, E.A. 1988. An overview of recent trends and developments in the use of unconventional feed ingredients for ruminant animals: applicability to the Nigerian conditions. Proceedings of National Workshop on Alternative Formulations of Livestock Feeds in Nigeria, organized by the Economic Affairs Office, The Presidency, held at ARMTI, Ilorin, 21-25 November 1988, p. 544-578.
Adebowale E.A., Orskov, E.R. & Shand, W.J. 1991. Use of ash of cocoapod husk as a source of alkali for upgrading agricultural residues with or without hydrogen peroxide. Trop. Agric., 68: 27-32.
Alhassan, W.S. 1985. The potential of agro-industrial byproducts and crop residues for sheep and goat production in Nigeria. In Small Ruminant Production in Nigeria. Proceedings of National Conference on Small Ruminant Production, NAPRI, Zaria, Nigeria, p. 165-183.
Chesson, A. 1981. Effects of sodium hydroxide on cereal straw in relation to the enhanced degradation of structural polysaccharides by rumen microorganisms. J. Sci. Food Agric., 32: 745-758.
Dzowela, B.H. 1987. Efforts to enhance maize stover utilization for small-holder livestock producers in Malawi. In Proceedings of ARNAB Workshop on the Utilization of Agricultural By-products as Livestock Feeds in Africa, p. 27-36.
FMAWR. 1988. Agricultural policy for Nigeria: strategies for implementation. Lagos, Federal Ministry of Agriculture, Water Resources and Rural Development.
French, M.H. 1943. Feeding values of stover from maize, millet and bulrush millet. East Afr. Agric. J., 9: 88-89.
Hartley, R.D. 1985. Chemistry of lignocellulosic plant materials and non-microbial processes for increasing their feed value for the ruminant. In Improved utilization of lignocellulosic materials in animal feed. Paris, OECD, p. 10-30.
Jackson, M.G. 1977. Review article: the alkali treatment of straws. Anim. Feed Sci. Technol., 2: 105-130.
Kategile, J.A. 1981. Digestibility of low quality roughages supplemented with concentrates. In J.A. Kategile, A.N. Said & F. Sundstol, eds. The utilization of low quality roughages in Africa. Proc. of Workshop, held in Arusha, Tanzania. AUN Agricultural Development Report No. 1. Norway, Aas NLH.
Mehrez, A.Z. & Orskov, E.R. 1977. A study of the artificial fibre bag technique for determining the digestibility of feeds in the rumen. J. Agric. Sci. (Camb.), 8: 645-650.
Orskov, E.R. & McDonald, I. 1979. The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage. J. Agric. Sci. (Camb.), 92: 499-503.
Singh, M. & Jackson, M.G. 1971. The effect of different levels of sodium hydroxide spray treatment of wheat straw on consumption and digestibility by cattle. J. Agric. Sci., 77: 5-10.
Sunstol, F., Coxworth, E. & Mowat, D.N. 1978. Improving the nutritive value of wheat straw and other low quality roughages by treatment with ammonia. World Anim. Rev., 26: 13-21.
