- Email: [email protected]
Recent work on the establishment, production and utilization of multipurpose trees as a feed resource in Zimbabwe
ANIMALFEED SCIENCEAND TECHNOLOGY ELSEVIER
Animal Feed Science Technology 69 (1997) l-15
Recent work on the establishment, production and utilization of multipurpose trees as a feed resource in Zimbabwe -__ ..,a,_ __ B.H. Uzowela”~“, L. Hove”,
Ii.v.
Iviaasciorp”, P.L. ‘Niafongoya”
“SADC-ICRAFAgroforestryProject,PO Box CY 594, Causeway,Harare, Zimbabwe bDepartmentof Researchand SpecialistServices,PO Box CY 594, Causeway,Harare,Zimbabwe cUniversityof Zimbabwe,Crop Science Department,PO Box MP167, Mt. Pleasant,Harare, Zimbabwe
Abstract
Recent work to establish and produce multipurpose trees is reviewed in terms of their production and roie in animai feeding systems. A great deai of variabiiity was found in fodder production, with Acacia angustissima, Leucaena leucocephala cv. Cunningham, Gliricidia sepium and to some extent Cajanus cajan producing the highest fodder yields at both Domboshawa and Makoholi sites. However, with C. cajun the yields at Makoholi were much lower than at Domboshawa. Among the alternative species to the psyllid-prone L. leucocephala, A. angustissima has shown superior fodder productivity. Within the Leucaena genus L. esculenta subsp. paniculata (OF1 52/87), L. diversifolia subsp. stenocarpa (OF1 53/88), L. pallida (G2137) and to some extent L. pulverulenta (OF1 84/87) have shown the greatest potential at both Domboshawa and Makoholi. Due to differences in chemical composition, the different fodder trees were variable in the extent to which they can be relied upon as feed resources in Zimbabwe. Notable differences were found in fibre content, in vitro dry matter digestibility, acceptability and intake by livestock and therefore, their potential in affecting animal product&y. 0 1997 Elsevier Science B.V. Keywords: Multipurpose
Chemical composition;
trees; Tree fodders; Feed resource; Fodder-production Secondary plant compounds
* Corresponding author. 0377~8401/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved PII SO377-8401(97)00091-6
potential;
2
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
1. Introduction The undisputed role of multipurpose trees as a feed resource in the tropics has been established (Jones and Jones, 1984; Davidson, 1987). The greatest value of multipurpose trees and shrubs lies in their role as diet supplements. This role relates to their supply of dietary nitrogen, energy, minerals and vitamins. In many parts of the subhumid tropics, there are regular feed shortages and droughts. Thus, the supplementation of livestock by the use of only cereal crop residues may result in live-weight losses due to the provision of digestible energy, but it perpetuates low animal productivity, since it cannot overcome the shortage of dietary protein (Devendra, 1989). Tree fodders provide a valuable source of supplementary protein in the diet of animals and can also improve the overall utilisation of feeds. For example, there are widespread cases where supplementation with leguminous tree leaves have increased the digestibility of low quality feedstuffs (Ivory, 1989). In Zimbabwe earlier accounts of the use of leguminous multipurpose trees point to the potential of pigeon pea (Cajanus cujan) to provide browse during the early dry season at Grasslands Research Station (Clatworthy et al., 1986). Depending on nlmntitv -l--“---J
nf
h&aoe
b-
nvnilnhle -‘-*-----
at --
first
ct&&o
b
and -__-
the .._-
wveritv “.“‘_,
gf
frost
) steers -.__*-
gained 0.22-0.34 kg animal-’ day-’ over a 30-90-day period (Mills, 1961). This performance was better than those of steers on highly fertilized grass pastures where gains were only 0.09-0.18 kg animal-r day-’ during the same early dry season period. In recent years, numerous leguminous browse species have undergone agronomic evaluation in fodder plantings in Zimbabwe (Manyawu et al., 1994). Accessions and provenances of Leucaena leucocephala, L. diversifalia, L. shannonii, Acacia angustissima and A. meamsii, for example, have adapted well to local conditions. However, these workers report that feeding strategies for these introduced multipurpose tree fodders (dried or fresh) have received limited attention. Their potential use as feed resources showed that i,. ieucocephaiu foiiowed by L. shannonii have twice the potential of L. diversifolia and A. angustissima and nearly three times the potential of A. meamsii. Differences in feed potential were attributed to differences in chemical composition (crude protein (CP), in vitro dry matter digestibility and the presence of condensed tannins). In more recent work the scope for multipurpose leguminous tree use as feed resources has gathered momentum through agroforestry. In order to tap the potential of multipurpose leguminous trees, a series of trials has been conducted with the aim of fitting them into Zimbabwean livestock production systems. Highlights of the work conducted in recent years will be reviewed in this paper.
2. Establishment / production work
Establishment work involving multipurpose fodder trees has focused on finding entry-points into crop production systems. This is mainly in the form of fodder lots or contour-bund plantings.
B.H. Dzowelaet al. /Animal Feed Science Technology69 (1997) l-15
3
2.1. Fodder lot plantings Work in this area has involved the setting aside of land for the planting of multipurpose tree fodders. Predominant in these plantings were L. leucocephala, A. angustissima, Calliandra calothyrsus, C. cajan, Gliricidia sepium, Gleditsia triacanthos and Flemingia macrophylla (syn. congesta), Sesbania macrantha and S. sesban. The
planting configuration involved a spacing of 2 m x 2 m. The harvesting procedure involved cutting once every twelve months at the end of the rainy season in May. Dry matter yields are presented in Table 1 for a 3-year period. High fodder yield potentials were demonstrated by A. angustissima, L. leucocephala cv. Cunningham, G. sepium, F. macrophylla and C. calothyrsus in decreasing order at Domboshawa (Table 1). At Makoholi, (Table 1) a site of lower agricultural potential based on rainfall and soil fertility than Domboshawa, the greatest fodder-production potential was demonstrated by G. sepium followed in decreasing order by A. angustissima, L. leucocephala, C. calothyrsus and F. macrophylla. At both sites, very poor fodder yields were observed for S. macrantha (or S. bispinosa at Makoholi only>, S. sesban and G. triacanthos. Simiiar work invoiving estabiishment of aiternative fodder tree species in a fodder lot system has involved the species C. cajan in which twenty medium to late maturing cultivars (acquired from the ICRISAT Centre) (Table 2) together with less known Leucaena species and provenances have been tested in order to seek environmentally better adapted and resistant alternatives to the psyllid-prone L. leucocephala (Table 3). A great deal of diversity in fodder-production potential was demonstrated both within and between sites. Variability was also observed between years within a site. The year-to-year variability was attributed to differences in amounts of rainfall received and in the ability of cultivars to coppice under a cutting regime fixed at 50 nf c.,h vn.-n ..,;n+c.,. “LLUIItdUbL. “I Ju”-L.b~” WIIILLI cm qh*.,n L+“““ti +hn L11tiground. A?other factor was the r\z-,-~~rrnrrnn temperatures that reduced the coppice ability due to frost damage. The pigeon pea cultivars with potential for fodder were, in order of decreasing fodder yield, Nos. 605, 13516, 666, Ex-Marondera (control) and KPP 605 at Domboshawa. At Makoholi it was Nos. 657/l, 66, 9141, E31/1 and EMYT9619, although yield levels were much lower than those achieved at Domboshawa (Table 2). High fodder yield potential was demonstrated over the years by L. esculenta subsp. paniculata, L. diversifolia subsp. stenocarpa and L. pallida at Domboshawa. These are the species that have also shown resistance to psyllid attack elsewhere (Alan Pottinger personal communication; Msangi et al., 1995). Thus, they would likely replace L. leucocephala in a psyllid-challenged environment. At Makoholi, a site presumed to have a harsher environment than Domboshawa on the basis of low soil fertility, low and erratic rainfall and the occurrence of frost, 10 leucaena species/provenances were evaluated (Table 3). The greatest potential for fodder yields overall was exhibited by L. esculenta subsp. paniculata, L. pulverulenta and the inter-specific hybrid of L. leucocephala and L. diversifolia. Others which
0.21
0.07
L. leucocephala cv. Cunningham
G. sepium (unknown source)
3.47
2.98
0.07
1.71
0.86
0.00 0.67
C. calothyrws (CPI 104627)
var. nubica (ex-Kenya)
S. macrantha (unknown source)
G. trimzanthos(unknown source)
Source: adapted from Dzowela and Hove (1995).
LSD (P < 0.05)
S. sesban
0.00 1.39
1.03
3.53
0.13
OF1 9/89 (ex-Guatemala)
C. calothyrsus
0.08
3.22
3.04
2.85
3.52
1992-1993
ILCA 14924 (ex-Thailand)
F. macrophylla
1.21
1991-1992
Domboshawa
0.09
0.09
3.88
2.11
4.69
6.23
6.87
7.06
8.16
8.87
10.26
0.00
0.00
2.11
3.21
3.75
5.04
5.81
5.53
Total
0.16 0.47
0.52
0.52
0.41
0.42
0.61
0.38
0.54
0.46
1991-1992
Makoholi
0.67 1.62
1.43
^ ^^ 3.63
U.YL
^ ^_ USJY
1.95
2.93 0.00
0.92
1.49
4.85
6.53
3.02 3.20
5.42
9.15
8.30
8.57
Total
1.82
6.34
5.69
4.85
1993-1994
1.24
3.09
2.99
2.43
2.06
3.26
1992-1993
established at Domboshawa and Makoholi in 1990-1991
1993-1994
for major species and provenances
ILCA 469 (ex-Belize)
A. angustksima
Treatments
Table 1 Fodder (leaf) dry matter yields (t ha-‘)
P
no.
Source:
adapted
605 13516 666 Ex-Marondera KPP 605 EMYT169 66 81/3/3 E31/4 No. 2 657/l 9141 12031 788 11047 E9/6 13125 12939 590 EMYT9619 LSD (P < 0.05)
Cultivar
from Dzowela
et al. (1994)
0.10 0.07 0.11 0.06 0.11 0.06 0.09 0.06 0.07 0.07 0.03 0.07 0.09 0.09 0.04 0.07 0.08 0.93 0.10 0.03 0.06 1.27 1.62 1.31 0.63 1.24 2.03 1.58 1.29 1.58 1.51 1.70 1.04 1.90 1.06 1.84 1.49 1.00 1.43 1.94 1.43 1.44
0.56 0.44 0.80 0.65 0.46 1.74 1.52 0.45 1.18 0.49 3.56 1.73 0.43 0.42 1.52 0.48 1.81 0.73 0.81 0.51 1.35
11.82 9.87 10.23 10.94 9.85 9.12 9.28 8.93 8.38 8.54 7.58 7.40 5.50 7.47 6.27 6.16 6.24 5.59 4.44 4.47 3.58
0.45 0.52 0.39 0.32 0.45 0.34 0.58 0.39 0.71 0.39 0.52 0.58 1.60 0.45 0.45 0.39 0.45 0.39 0.41 0.45 0.25
Makoholi
1993-1994
with establishment
Domboshawa
and Makohoh
Makoholi
at Domboshawa
1992-1993
production
Domboshawa
for fodder
1991-1992
evaluation
Domboshawa
Cajanus cajan accession
Table 2
0.82 1.89 1.06 0.56 0.39 0.59 2.37 0.82 1.69 0.36 0.58 1.47 0.67 0.80 0.81 0.40 0.72 1.26 0.64 2.30 0.97
Makoholi
in 1990-1991:
13.54 12.00 11.93 11.89 11.55 11.49 11.45 10.61 10.58 10.44 9.80 9.02 8.99 8.98 8.56 8.03 7.70 7.40 6.79 5.96
’ DM)
1.48 2.41 1.93 1.27 1.78 2.39 3.98 1.37 2.93 0.93 4.11 3.28 1.17 1.31 2.44 0.99 2.26 2.07 1.53 2.89 -
Makoholi
yields (t ha-
Domboshawa
Totals
fodder
esculenta subsp. paniculataa diuersifolia subsp. stenocarpa palltib leucocephala x L. diversifolia
OF1 52/87 OF1 53/88 G2137 ILCA 15090 (parent = K743) OFI 34/88 OF1 58/88 ILCA 15009 OFI 45/87 OF1 19/84 OF1 35/88 OF1 47/87 OF1 48/87 OF1 83/87 OF1 61/88 OF1 46/87 OF1 2/86 OF1 84/87
oxford/ other nos. 5.45 5.10 3.18 1.67 2.19 2.58 1.63 2.16 1.60 0.92 0.45 0.70 0.00 0.00 0.00 0.71
5.79 3.54 3.71 3.76 1.47 0.70 1.34 0.67 0.73 1.14 1.11 0.24 0.03 0.00 0.03 2.72
0.74 0.17 0.91 0.53 0.40 0.46 0.66 0.31 0.45 0.57 0.49 0.13 0.38 0.12 0.06 0.36 -
1.08 0.41 0.12 0.09
5.96 4.06 3.74 3.63 3.14 2.78 2.63 2.06
11.97 8.81 7.80
Total
4.83 3.04 0.57 5.81 6.29 2.76 1.11 10.23 1.91
-
11.83 5.03
1992-1993
1994-1995
1992-1993
1993-1994
Makoholi
Domboshawa
10.48 5.19 1.38 8.98 9.52 3.59 2.02
14.31
2.23 0.94
2.67 0.83 0.42 1.61 1.78 0.36 0.24 -
2.97 1.32 0.39 1.56 1.45 0.47 0.67 -
-
1.75 1.36
-
-
7.53
-
1.36
1.14
16.45 -
Total
-
2.72
1994-1995
1.90 -
1993-1994
species and provenances at Domboshawa and Makoholi, established in 1991-1992
aL. esculenta subsp. paniculata (OF1 52/87) is synonymous with L. pallida (Alan Pottinger, personal communication). bOffspring of CPI 85890. Source:Adapted from Dzowela and Hove, 1995.
L. salvadorensis L. shannonii subsp. magnifica L. leucocephala x L. diuersijolia L. diwrsifolia subsp. divers~olia L. shannonii subsp. rnagnifica L. diversifolia subsp. stenocarpa L. esculenta subsp. esculenta L. esculenta subsp. esculenta L. pulverulenta L. m’chodes L. diversifolia subsp. diversifolia L. trichodes L. pulverulenta LSD (P < 0.05)
L. L. L. L.
Treatments
Table 3 Fodder yields (t ha-’ DM) of new Ieucaena
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
7
showed promise were L. esculenta subsp. esculenta and L. diversifolia subsp. stenocarpa. 2.2. Planting on contour-bunds
This fodder technology assumes that the field contour-bund, which is primarily constructed for soil and water conservation, is an idle piece of land in the cropland. Thus, it can be used as an entry-point for integrating fodder production in a maize farming system (Ingram and Swift, 1989). This has the advantage of not competing for the same piece of land with crops in the inter-bund area. A trial was, therefore, set up to assess the fodder-production potential of contour-bund grown multipurpose trees. The planting configuration covered a 2-m wide bund area, in which a four-row hedge was planted at a spacing of 0.5 m X 0.5 m. Each fodder species occupied a strip 8 m long. Maize rows were planted 0.45 m away from the hedges of A. angustissima, C. calothyrsus, L. leucocephala and Napier grass (previously it was C. cajun). All fodders were side-pruned twice during the wet season and the cutting management was sequentially designed such that cutting coincided with the end of January, February, March and/or April. This cutting management was deemed necessary to minimize competition with maize and the study aimed to determine the best cutting time to take advantage of residual soil moisture and thus encourage regrowth and accumulation of dry season standing fodder. The January-February cutting times increased maize yields of the adjacent rows of maize by 15-20% compared to the March-April cuttings. The early cutting (January-February) resulted in fodder yield during the dry season of the order of 0.6-0.8 t DM ha-’ (Table 4). In the 1993-1994 season A. angustissima produced the largest amount of fodder (Table 4). The fodder yield potential of A. angustissima (837 kg DM ha-’ > was almost double that achieved by the other species. Assuming a 300-kg live-weight livestock unit consuming 10 kg DM day-’ and supplemented at the rate of 30% of its daily ration, this would give 279 feeding days or 9.3 months of supplementation. This then would supplement 3 livestock units during the most critical times of the dry season (August-October). Extending this argument, the total 1994-1995 fodder-production figures provide 1523, 1430 and 1700 supplementary feeding days from A. angustissima, C. calothyrsus and L. leucocephala respectively and thus livestock units 17, 16 and 19, respectively to be supplemented during the August-October period of the dry season.
3. Chemical composition Dzowela et al, (1995b) have shown that representative multipurpose tree fodders showing the greatest potential use in agroforestry systems in Zimbabwe, sampled at 6-12 weeks regrowths have crude protein contents ranging from 189 g kg-’ DM in F. macrophylla to 292 g kg-’ DM in A. angustissima. Acid detergent fibre (ADF) content was low in S. sesban (99 g kg-’ DM) while ADF contents in F. macrophylla
8
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) l-15
Table 4 Prunings and cut fodder yields in kg DM per running metre of contour hedge (figures in parenthesis on hectare basis)“, with trees established in 1992-1993 1993-1994
A. angustissima C. cajan Asc. Ex-Maronderab
199441995 Wet season
Dry season
1.674 (837)
7.47 (3735)
1.67 (835)
0.951(476) -
0.94 (470)
N.A.
L. leucocephala
0.824 (412) 1.121 (561)
7.33 (3665) 8.68 (4340)
1.25 (625) 1.52 (760)
LSD (P < 0.05)
0.369 (185)
1.15 (576)
ns
Napier fodder C. calothyrsus
-
aAssumption: each MPT fodder strip is 100 m long and at a 4% slope there are five-contour bunds in hectare spaced approximately 20 m apart. bC. cajan died off during the 1994 dry season due to frost damage, and was replaced by the perennial grass Pennisetum purpureum (Napier grass). Source: adapted from Dzowela and Hove (1995).
(277 g kg-’ DM) and C. cajun (255 g kg-’ DM) were the highest. Ash content ranges from 58 g kg-’ DM in F. macrophylla to 95 g kg-’ DM in S. se&an. MPTs with detectable amounts of condensed tannins were A. angustissima (10.3 g kg-’ DM), C. culothyrsus (17.9 g kg-’ DM) and F. macrophyllu (3.4 g kg-’ DM).
Condensed tannin contents were associated with poor rumen degradability (DM and N) when compared with MPTs (C. cajun, G. sepium, L. leucocephula, S. macranthu, S. sesbun) without detectable condensed tannin contents. Dzowela et al. (1995b) report that G. sepium, S. mucrunthu and S. sesbun have the lowest ADF values of all MPT fodders studied (Table 5). Similarly these same species had the lowest NDF values and especially the lowest complexity with lignin and thus, had the highest IVDMD values. Levels of soluble polyphenolics ranged from 23 to 154 g kg-’ DM in the different MPT fodders, the lowest being in G. sepium, C. cujan and the highest in C. calothyrsus. While total N ranged from 20 to 33 g kg-’ DM about 60% of this on average was bound to NDF, the highest proportion of N bound to NDF occuring in C. calothyrsus and C. cajun (90% and 82%, respectively). Leucuenu leucocephala was atypical in that only 41% of its N of 32 g kg-’ DM was bound to NDF. Thus, it would appear that the higher the proportion of NDF complexed with lignin and condensed tannins, the lower the IVDMD. An exception in the case of condensed tannins was G. sepium on which Mafongoya et al. (1996) have reported that its condensed tannins have a lower complexing capacity and therefore, result in higher rumen degradability (Dzowela et al., 1995a). Differences in chemical composition have a strong bearing on the potential use of the leguminous MPT fodders in feeding systems (Table 5). They affect palatability and intake by livestock (Table 6) both within and between species and provenances. In a study undertaken at Makoholi in 1993, Dzowela et al. (1994) found a
9
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) l-15
Table 5 Chemical composition (g kg- ’ DM) of sun-dried major multipurpose tree fodders in Zimbabwe MPT spp.
ADF
NDF
A. angustissima C. cajan C. calothyrsus F. macrophylla G. sepium L. leucocephala S. macrantha S. sesban
571 493 486 545 438 541 476 476
629 574 587 595 538 589 537 490
Mean S.D.(k)
449 168
567 43
Lignin
Soluble polyphenols
-________ 143 165 114 193
Total N
_~~__
NDF-N
~~.
IVDMD
_ ~~~~
Condensed tannins Abs ssonm g -1 NDF
~_~~
122 42 154 105
31 33 20 24
21 27 18 19
401 356 358 277
16 89 53 103
209
111
23
31
25
510
122
122
32
13
437
50
NA
NA
NA
NA
540
NA
61
112
28
21
663
16
131 41
97 47
28 5
21 5
443 123
77 67
Source: adapted from Dzowela et al. (1995).
great deal of variability among the 10 species and provenances tested. Goats consumed most of the browses on offer, rejecting only A. holosericea and C. cajun hay. On the other hand, sheep accepted only one browse species (C. calothyrsus). For the MPT browses accepted by goats intakes ranged from 52 g (A. uuriculoforks hay) to 862 g dry matter animal-’ day- ’ CL. leucocephulu cv. Hawaiian Giant) by goats. Intake of the herbaceous legume L. leucocephalu was higher than that of most browses (Table 6). Even within a genus such as Leucaenu, a great deal of variability was observed in palatability or acceptability by goats (Dzowela et al., 1994) when 10 lesser known Leucuenu species and provenances were evaluated in a cafeteria system using individually penned indigenous goats. Three L. leucocephulu lines (Hawaiian giant, Cunningham and Peru) were included as controls. Species and provenances had a significant (P < 0.05) effect on palatability with the common L. leucocephulu lines being less preferred than some of the lesser known species and provenances (Table 7). It is argued that secondary plant compounds probably influenced palatability and intake. This is particularly true when comparison in palatability is made between the L. esculentu subsp. esculentu provenances (Table 7).
4. Livestock production / performance
Browseable trees and shrubs are a more reliable feed resource than herbaceous plants as they are able to retain green foliage during the dry season and drought periods. Although browses from MPTs currently being tested for use in agroforestry have desirable concentrations of most nutrients (Dzowela et al., 1994; Dzowela et al., 1995a,b), the presence of secondary plant compounds in some
10
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
Table 6 Dry matter intake (g hd-’ day-‘) of various browses by sheep and goats Animal species
MFT Fodder spp.
Mean intake
SE.
Goats
L. leucocephala G. sepium L. pulverulenta A. angustissima F. macrophyla C. cajan (fresh) C. calothyrsus S. sesban A. auriculifomk A. holosericea C. cajan (hay)
862 699 677 494 443
88 135 117 31 8
414
47
410 224 52 0
10 20 9 0
Sheep
C. calothyrsus C. cajan (hay) C. cajan (fresh) A. holosericea
0
0
449
9
0 0
0 0
0
0
Source: adapted from Dzowela et al. (1994).
species could interfere with nutrient use efficiency. A few studies are reported which quantify animal responses to diets containing these browses under Zimbabwe farming systems. A study was undertaken by the SADC-ICRAP Agroforestry Project (Dzowela et al., 1994) using goats on a basal diet of native pasture grass hay. Levels of 110, 140, 160 and 130 g of A. angustissima, C. calothyrsus, F. macrophylla and L. leucocephala respectively or a mixture of 55 g of A. angustissima and 65 g of L. leucocephala were fed as supplements. The diets were isonitrogenous and provided 4 g N animal-’ day-‘. Animals readily consumed browse supplement (as sun-dried hay). Native grass hay intake decreased while total dry matter intake increased (P < 0.05) following supplementation with browses except A. angzkssima (Table 8). Synergistic effects were apparent between A. angustissima and L. leucocephala for both native grass pasture hay intake and total dry matter intake. Browse supplementation resulted in higher (P < 0.05) growth rates than animals receiving grass hay alone. Animals receiving native pasture grass hay alone lost weight throughout the feeding period while those receiving A. angustissima, F. macrophylla and L. leucocephala had similar (P > 0.05) growth rates. Animals fed C. calothyrsus and a mixture of A. angustissima and L. leucocephala grew faster 0’ < 0.05) than the rest of the animals. Acacia angustissima and L. leucocephalu behaved synergistically for animal growth rates. In situations where the leaf material is used for soil organic manuring, the pods of trees such as L. leucocephala could be used directly as feed. A study conducted to investigate this potential using goats revealed that intake of pods was low ( < 100 g hd-l d-i) and similar (P > 0.05) at both levels of supplementation (150 g and
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) l-15
11
Table I Variation among Leucaena sp. offered as whole diets to goats Species/provenances
Origin/code
Palatability indexa
Mexico, OFI 52/87
1.00
Mexico, OFI 47/87 Hawaii
1.00 0.92
Guatemala, OFI 19/84 Mexico, OFI 83/87
0.90 0.88
ILCA No. 15009
0.79
Guatemala, OF1 53/88
0.67
Mexico, OF1 45/87 USA, OFI 84/87 G2137 (parent CPI85890)
0.66 0.57 0.55
Mexico, OF1 48/87 Cunningham Peru
0.44 0.42 0.23
L. esculenta subsp.
paniculata L. esculenta subsp.
esculenta L. leucocephala (control1 L. shannonii subsp.
magnifica L. L. L. L.
pulverulenta leucocephala x diversifolia diversifolia subsp.
stenocarpa L. diversifolia subsp.
diversifolia L. pulverulenta L. pallida L. esculenta subsp.
esculenta L. leucocephala (control) L. leucocephala (control)
DM intake a Palatability index =
DM offered ’
Source: adapted from Dzowela et al. (1994).
Table 8 Dry matter (DM) intake and growth rates (g hd-’ day-‘) supplements to native pasture hay Treatments
Supplement
Hay
AA
alone Intake: native pasture hay Total DM intake Growth rate
of goats fed browses from MPTs as
386 386 -20
AA+
LL
CC
FM
S.E.D.
305 434 16
282 419 24
276 420 9
18 21 5
LL
260 363 12
299 416 20
AA, Acacia angustissima; AA + LL, Acacia angustissima -t Leucaena leucocephala; CC, Calliandra calothyrsus; FM, Flemingia macrophylla.
leucocephala;
LL, Leucaena
Source: adapted from Dzowela et al. (1994).
250 g pods day-‘). Although diets had similar (P > 0.05) effects on grass hay and total dry matter intakes, substitution was apparent at 250 g of pods per day (Table 9). The higher pod intake adversely affected both dry matter intake and average
12
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
Table 9 Intake and growth of goats receiving dry L. leucocephala pods as a supplement to rangeland grass hay Diet
Native hay alone Native hay + 150 g pods/day Native hay + 250 g pods/day S.E.D.
Intake (g kg-’ live-weight)
Daily LWG gain (g hd-’ day- ‘)
Hay
Total DM
28
28
14
30
33
49
26 2.6
30 2.5
30 12.5
Source: Dzowela et al. (1994).
daily liveweight gain. The cause of the decline is not clear although mimosine toxicity is a possibility, since these local goats lack the rumen bacteria (Synergistes jonesii) capable of detoxifying this amino acid (Jones, 1994). However, there was a significant response in live-weight gain to rangeland hay supplemented with L. leucocephala pods (Hove, unpublished data). In the Zimbabwean production system, livestock lose up to 30% of their pre-dry season live-weight in the dry season (John Mupangwa, pers. comm.). Several methods can be used to alleviate this problem. Chief among these is the use of conventional protein supplements such as Rumevite@, a commercially available supplement. Rumevite @ is intended to supply extra protein, minerals (P, Ca and S> and thus sustain live-weights during the dry season when livestock subsist on poor quality diets. The use of conventional protein supplements in the smallholder sector is limited mainly by their high costs. A cheaper source of protein supplement for this generally resource-poor farming sector is fodder from tropical leguminous trees. In order to determine their potential, a study was undertaken locally to evaluate the effect of feeding fresh L. leucocephala as a protein supplement to steers receiving a basal diet of veld grass hay fed ad libitum during a 90-day period of the dry season at Domboshawa in 1994. Eight yearling steers aged lo-months (average live-weight 139 k 3.9 kg), were assigned to two treatment groups of four steers per group based on live-weight. Each group was housed separately for the duration of the trial, from 1st September to 8th December. One group was supplemented with fresh Leucaena leaf (24.8% CP) at the rate of 0.80-1.0 kg DM animal-’ day-l, i.e 0.20-0.25 kg CP intake head-’ day-‘. The other group was supplemented with Rumevite@ lick for 1 h daily; Rumevite@ contained 34% CP made up of 30% CP from concentrate and 4% CP from urea. This was consumed at the rate of 0.17-0.20 kg CP head-’ day-‘. The live-weight gain associated with supplementation with Leucaena was 0.30 f 0.11 kg head-’ day-’ compared with only 0.14 f 0.07 kg/head day-’ with Rumevite@. Furthermore, Rumevite@-supplemented animals completed the dry season at an average live-weight of 150 kg whereas those supplemented with
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
13
Leucaena
completed at a higher live-weight of 167 kg (Fig. 1). These data established the potential of substituting Rumevite@ with a multipurpose leguminous fodder tree such as Leucaena. Taking into account the fact that Rumevite@ has to be purchased, the Leucaena can be home-grown, the only substantial cost is the labour involved with cutting and carrying the leaf to feeding pens. Labour however, during the dry season (August to November), has a very low opportunity cost as there are few farm activities at this time.
5. Discussion of role of tree fodders in feeding systems The great diversity among the different multipurpose leguminous tree fodders in Zimbabwe point to different potentials in their use as a livestock feed resource. The biophysical limit imposed by site of establishment on production is evident in
4 Weeks
6 0 of feeding
fed a basal
of veld grass
10
12
-Rumevite +Leucaena Fig. 1. Live-weight Rumevite’
changes
of steers
hay supplemented
with leucaena
or
14
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
the comparison made between the potential at Domboshawa on the one hand and Makoholi on the other. This has implications for the choice of species and provenances to be planted. The choice of a species and indeed a provenance will depend on what role that feed resource has in a feed-year-budgeting. Furthermore, it will depend on how readily acceptable the browse species is by livestock. Another implication of the biophysical constraints has to do with the management and thus in what form (fresh or hay) the feed resource is to be presented. The most abundant feed resources in Zimbabwe during the wet season are grass (native veld pastures), planted fertilized pastures (Cynodon spp.; Chloris guymu) and Napier grass fodder (Pennisetumpulpureum) or its inter-specific hybrid with P. typhoides (Syn. americunum), Bana. During this time protein contents are within the range of ll-14% of the dry matter, sufficient for modest livestock productivity (NRC, 1984). However, during the dry season, the crude protein concentration of these feed resources and especially crop residues (cereal crop stovers) could be lower than the critical level of 7% required for ruminal function (ARC, 1980; NAS, 1976). Thus, it is during this period that multipurpose leguminous tree fodders have a supplementary or substitution role for bought-in feeds (Fig. 1). The farmer may have to make decisions on how to present the supplement. For some species (e.g. C. cajun) intake is drastically reduced when presented in hay form especially to goats. Due to limitations imposed by climate (long dry season and cool winters) most of the multipurpose tree fodders would lose their foliage; thus, the need to conserve them as hay is imperative, sometime in March/April. Conservation, evens out the feed-supply to cover the most lean times of the year. It also reduces the amount of standing tree biomass likely to suffer from frost damage. Furthermore, it optimises use of the residual soil moisture for the tree coppice and regrowth much earlier (i.e. July-August as opposed to September-October) (Dzowela, unpublished data). In the context of the Zimbabwe farming systems, it is not enough to have and promote a multipurpose tree fodder on the basis of high fodder productivity alone. For instance, very high fodder yields have been realized from G. sepium at both Domboshawa and Makoholi sites, the species suffers severely from cool winters in June-July resulting in leaf loss and stem and branch die-back. Green leaf is not present in the dry season and the trees do not flower and set seed. The tree requires live stem/branches surface area for flowering and seed production, thus in frost-prone areas it cannot be sustained without seed production locally. Cullian&a culothyrsus also has a problem with seed setting though it does flower. Other factors to consider in the choice of species and indeed provenances include ease of establishment from locally produced seed, acceptability by animals (palatability), high nutrient content and the toxic effects of secondary plant compounds such as condensed tannins on animal performance and production.
Acknowledgements
The financial support of the Canadian International Development Agency (CIDA) is gratefully acknowledged, as is the logistical support of the Department of
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) 1-15
Research and Specialist Services, Zimbabwe Research in Agroforestry (ICRAF?.
and the International
15
Centre
for
References ARC (Agricultural Research Council), 1980. The Nutrient Requirements of Ruminant Livestock. Technical review by an Agricultural Research working party. Commonwealth Agricultural Bureaux, Farnham Royal, UK, pp. 351. Clatworthy, J.N., MacLaurin, A.R., Avila, M., 1986. The possible role of forage legumes in communal area farming systems in Zimbabwe. In: Haque, I., Jutzi, S., Neate, P.J.H. (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, pp. 265-288. Davidson, S., 1987. Adopting Leucaena - achievement and a new problem. Rural Res. 134, 22-27. Devendra, C., 1989. The use of shrubs and tree fodders by ruminants. In: Shrubs and Tree Fodders for Farm Animals, Proceedings of a workshop in Denpasar, Indonesia 24-29 July 1989, IDRC, Ottawa, Canada, pp. 42-60. Dzowela, B.H., Hove, L., 1995. SADC-ICRAF Agroforestry Project, Zimbabwe, 1994-1995 Annual Report (Highlights), pp. 91. Dzowela, B.H., Hove, L., Mafongoya, P.L., 1994. SADC-ICRAF Agroforestry Project, Zimbabwe, Annual Progress Report, pp. 86. Dzowela, B.H., Hove, L., Topps, J.H., Mafongoya, P.L., 1995. Nutritional and anti-nutritional characters and rumen digestibility of dry matter and nitrogen for some multipurpose trees species with potential for agroforestry in Zimbabwe. Anim. Feed Sci. Technol. 55, 207-214. Dzowela, B.H., Hove, L., Mafongoya, P.L., 1995. Effect of drying method on chemical composition and in vitro digestibility of multipurpose tree and shrub fodders. Trop. Grass]. 29, 263-269. Ingram, J.A., Swift, M.J., 1989. Sustainability of cereal-legume inter-crops in relation to management of soil organic matter and nutrient cycling. Farm. Sys. Bull.: East. South. Afr. 4, 7-21. Ivory, D.A., 1989. Major characteristic, agronomic features and nutritional value of shrubs and tree fodders. In: Shrubs and Tree Fodders for Farming Animals. Proceedings of a workshop in Denpasar, Indonesia, 24-29 July 1989, IDRC, Ottawa, Canada, pp. 22-38. Jones, R.M, Jones, R.J., 1984. The effect of Leucaena leucocephala on liveweight gains, thyroid size and thyroxine levels of steers in south-eastern Queenland. Aust. J. Exp. Agr. Anim. Husb. 24, 4-9. Jones, R.M., 1994. The role of Leucaena in improving the productivity of grazing cattle. In: Gutteridge, R.C., Shelton, H.M. (Eds.), Forage Tree Legumes in Tropical Agriculture. CAB International Wallingford, UK pp. 216-231. Mafongoya, P.L., Nair, P.K.R., Dzowela, B.H., 1996. Nitrogen recovery by maize: 1 Effect of multipurpose tree pruning quality and method of pruning application. Submitted to Agroforestry Systems. Manyawu, G.J., Chakoma, C., Chakoma, I., Mugwagwa, E., 1994. Rumen degradation characteristics of five browse foliages. Annual Report for the Division of Livestock and Pastures, Department of Research and Specialist Services, Harare, pp. 17-19. Mills, P.F.L., 1961. Pigeon pea as a pasture legume in the high rainfall sandveld regions of Southern Rhodesia. Rhod. Agric. J. 58, 171-172. Msangi, R., Gama, B.M., Otsyina, R., 1995. Research Highlights In: SADC-ICRAF Agroforestry Research Project, Tumbi, Tabora, Tanzania, pp. 30. NAS (National Academy of Sciencewazzu), 1976. Nutrient requirements for beef cattle. National Academy of Sciences, Washington, DC. NRC (National Research Council), 1984. Nutrient requirements of beef cattle. 6th edn. (NAS: Washington, DC).
Animal Feed Science Technology 69 (1997) l-15
Recent work on the establishment, production and utilization of multipurpose trees as a feed resource in Zimbabwe -__ ..,a,_ __ B.H. Uzowela”~“, L. Hove”,
Ii.v.
Iviaasciorp”, P.L. ‘Niafongoya”
“SADC-ICRAFAgroforestryProject,PO Box CY 594, Causeway,Harare, Zimbabwe bDepartmentof Researchand SpecialistServices,PO Box CY 594, Causeway,Harare,Zimbabwe cUniversityof Zimbabwe,Crop Science Department,PO Box MP167, Mt. Pleasant,Harare, Zimbabwe
Abstract
Recent work to establish and produce multipurpose trees is reviewed in terms of their production and roie in animai feeding systems. A great deai of variabiiity was found in fodder production, with Acacia angustissima, Leucaena leucocephala cv. Cunningham, Gliricidia sepium and to some extent Cajanus cajan producing the highest fodder yields at both Domboshawa and Makoholi sites. However, with C. cajun the yields at Makoholi were much lower than at Domboshawa. Among the alternative species to the psyllid-prone L. leucocephala, A. angustissima has shown superior fodder productivity. Within the Leucaena genus L. esculenta subsp. paniculata (OF1 52/87), L. diversifolia subsp. stenocarpa (OF1 53/88), L. pallida (G2137) and to some extent L. pulverulenta (OF1 84/87) have shown the greatest potential at both Domboshawa and Makoholi. Due to differences in chemical composition, the different fodder trees were variable in the extent to which they can be relied upon as feed resources in Zimbabwe. Notable differences were found in fibre content, in vitro dry matter digestibility, acceptability and intake by livestock and therefore, their potential in affecting animal product&y. 0 1997 Elsevier Science B.V. Keywords: Multipurpose
Chemical composition;
trees; Tree fodders; Feed resource; Fodder-production Secondary plant compounds
* Corresponding author. 0377~8401/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved PII SO377-8401(97)00091-6
potential;
2
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
1. Introduction The undisputed role of multipurpose trees as a feed resource in the tropics has been established (Jones and Jones, 1984; Davidson, 1987). The greatest value of multipurpose trees and shrubs lies in their role as diet supplements. This role relates to their supply of dietary nitrogen, energy, minerals and vitamins. In many parts of the subhumid tropics, there are regular feed shortages and droughts. Thus, the supplementation of livestock by the use of only cereal crop residues may result in live-weight losses due to the provision of digestible energy, but it perpetuates low animal productivity, since it cannot overcome the shortage of dietary protein (Devendra, 1989). Tree fodders provide a valuable source of supplementary protein in the diet of animals and can also improve the overall utilisation of feeds. For example, there are widespread cases where supplementation with leguminous tree leaves have increased the digestibility of low quality feedstuffs (Ivory, 1989). In Zimbabwe earlier accounts of the use of leguminous multipurpose trees point to the potential of pigeon pea (Cajanus cujan) to provide browse during the early dry season at Grasslands Research Station (Clatworthy et al., 1986). Depending on nlmntitv -l--“---J
nf
h&aoe
b-
nvnilnhle -‘-*-----
at --
first
ct&&o
b
and -__-
the .._-
wveritv “.“‘_,
gf
frost
) steers -.__*-
gained 0.22-0.34 kg animal-’ day-’ over a 30-90-day period (Mills, 1961). This performance was better than those of steers on highly fertilized grass pastures where gains were only 0.09-0.18 kg animal-r day-’ during the same early dry season period. In recent years, numerous leguminous browse species have undergone agronomic evaluation in fodder plantings in Zimbabwe (Manyawu et al., 1994). Accessions and provenances of Leucaena leucocephala, L. diversifalia, L. shannonii, Acacia angustissima and A. meamsii, for example, have adapted well to local conditions. However, these workers report that feeding strategies for these introduced multipurpose tree fodders (dried or fresh) have received limited attention. Their potential use as feed resources showed that i,. ieucocephaiu foiiowed by L. shannonii have twice the potential of L. diversifolia and A. angustissima and nearly three times the potential of A. meamsii. Differences in feed potential were attributed to differences in chemical composition (crude protein (CP), in vitro dry matter digestibility and the presence of condensed tannins). In more recent work the scope for multipurpose leguminous tree use as feed resources has gathered momentum through agroforestry. In order to tap the potential of multipurpose leguminous trees, a series of trials has been conducted with the aim of fitting them into Zimbabwean livestock production systems. Highlights of the work conducted in recent years will be reviewed in this paper.
2. Establishment / production work
Establishment work involving multipurpose fodder trees has focused on finding entry-points into crop production systems. This is mainly in the form of fodder lots or contour-bund plantings.
B.H. Dzowelaet al. /Animal Feed Science Technology69 (1997) l-15
3
2.1. Fodder lot plantings Work in this area has involved the setting aside of land for the planting of multipurpose tree fodders. Predominant in these plantings were L. leucocephala, A. angustissima, Calliandra calothyrsus, C. cajan, Gliricidia sepium, Gleditsia triacanthos and Flemingia macrophylla (syn. congesta), Sesbania macrantha and S. sesban. The
planting configuration involved a spacing of 2 m x 2 m. The harvesting procedure involved cutting once every twelve months at the end of the rainy season in May. Dry matter yields are presented in Table 1 for a 3-year period. High fodder yield potentials were demonstrated by A. angustissima, L. leucocephala cv. Cunningham, G. sepium, F. macrophylla and C. calothyrsus in decreasing order at Domboshawa (Table 1). At Makoholi, (Table 1) a site of lower agricultural potential based on rainfall and soil fertility than Domboshawa, the greatest fodder-production potential was demonstrated by G. sepium followed in decreasing order by A. angustissima, L. leucocephala, C. calothyrsus and F. macrophylla. At both sites, very poor fodder yields were observed for S. macrantha (or S. bispinosa at Makoholi only>, S. sesban and G. triacanthos. Simiiar work invoiving estabiishment of aiternative fodder tree species in a fodder lot system has involved the species C. cajan in which twenty medium to late maturing cultivars (acquired from the ICRISAT Centre) (Table 2) together with less known Leucaena species and provenances have been tested in order to seek environmentally better adapted and resistant alternatives to the psyllid-prone L. leucocephala (Table 3). A great deal of diversity in fodder-production potential was demonstrated both within and between sites. Variability was also observed between years within a site. The year-to-year variability was attributed to differences in amounts of rainfall received and in the ability of cultivars to coppice under a cutting regime fixed at 50 nf c.,h vn.-n ..,;n+c.,. “LLUIItdUbL. “I Ju”-L.b~” WIIILLI cm qh*.,n L+“““ti +hn L11tiground. A?other factor was the r\z-,-~~rrnrrnn temperatures that reduced the coppice ability due to frost damage. The pigeon pea cultivars with potential for fodder were, in order of decreasing fodder yield, Nos. 605, 13516, 666, Ex-Marondera (control) and KPP 605 at Domboshawa. At Makoholi it was Nos. 657/l, 66, 9141, E31/1 and EMYT9619, although yield levels were much lower than those achieved at Domboshawa (Table 2). High fodder yield potential was demonstrated over the years by L. esculenta subsp. paniculata, L. diversifolia subsp. stenocarpa and L. pallida at Domboshawa. These are the species that have also shown resistance to psyllid attack elsewhere (Alan Pottinger personal communication; Msangi et al., 1995). Thus, they would likely replace L. leucocephala in a psyllid-challenged environment. At Makoholi, a site presumed to have a harsher environment than Domboshawa on the basis of low soil fertility, low and erratic rainfall and the occurrence of frost, 10 leucaena species/provenances were evaluated (Table 3). The greatest potential for fodder yields overall was exhibited by L. esculenta subsp. paniculata, L. pulverulenta and the inter-specific hybrid of L. leucocephala and L. diversifolia. Others which
0.21
0.07
L. leucocephala cv. Cunningham
G. sepium (unknown source)
3.47
2.98
0.07
1.71
0.86
0.00 0.67
C. calothyrws (CPI 104627)
var. nubica (ex-Kenya)
S. macrantha (unknown source)
G. trimzanthos(unknown source)
Source: adapted from Dzowela and Hove (1995).
LSD (P < 0.05)
S. sesban
0.00 1.39
1.03
3.53
0.13
OF1 9/89 (ex-Guatemala)
C. calothyrsus
0.08
3.22
3.04
2.85
3.52
1992-1993
ILCA 14924 (ex-Thailand)
F. macrophylla
1.21
1991-1992
Domboshawa
0.09
0.09
3.88
2.11
4.69
6.23
6.87
7.06
8.16
8.87
10.26
0.00
0.00
2.11
3.21
3.75
5.04
5.81
5.53
Total
0.16 0.47
0.52
0.52
0.41
0.42
0.61
0.38
0.54
0.46
1991-1992
Makoholi
0.67 1.62
1.43
^ ^^ 3.63
U.YL
^ ^_ USJY
1.95
2.93 0.00
0.92
1.49
4.85
6.53
3.02 3.20
5.42
9.15
8.30
8.57
Total
1.82
6.34
5.69
4.85
1993-1994
1.24
3.09
2.99
2.43
2.06
3.26
1992-1993
established at Domboshawa and Makoholi in 1990-1991
1993-1994
for major species and provenances
ILCA 469 (ex-Belize)
A. angustksima
Treatments
Table 1 Fodder (leaf) dry matter yields (t ha-‘)
P
no.
Source:
adapted
605 13516 666 Ex-Marondera KPP 605 EMYT169 66 81/3/3 E31/4 No. 2 657/l 9141 12031 788 11047 E9/6 13125 12939 590 EMYT9619 LSD (P < 0.05)
Cultivar
from Dzowela
et al. (1994)
0.10 0.07 0.11 0.06 0.11 0.06 0.09 0.06 0.07 0.07 0.03 0.07 0.09 0.09 0.04 0.07 0.08 0.93 0.10 0.03 0.06 1.27 1.62 1.31 0.63 1.24 2.03 1.58 1.29 1.58 1.51 1.70 1.04 1.90 1.06 1.84 1.49 1.00 1.43 1.94 1.43 1.44
0.56 0.44 0.80 0.65 0.46 1.74 1.52 0.45 1.18 0.49 3.56 1.73 0.43 0.42 1.52 0.48 1.81 0.73 0.81 0.51 1.35
11.82 9.87 10.23 10.94 9.85 9.12 9.28 8.93 8.38 8.54 7.58 7.40 5.50 7.47 6.27 6.16 6.24 5.59 4.44 4.47 3.58
0.45 0.52 0.39 0.32 0.45 0.34 0.58 0.39 0.71 0.39 0.52 0.58 1.60 0.45 0.45 0.39 0.45 0.39 0.41 0.45 0.25
Makoholi
1993-1994
with establishment
Domboshawa
and Makohoh
Makoholi
at Domboshawa
1992-1993
production
Domboshawa
for fodder
1991-1992
evaluation
Domboshawa
Cajanus cajan accession
Table 2
0.82 1.89 1.06 0.56 0.39 0.59 2.37 0.82 1.69 0.36 0.58 1.47 0.67 0.80 0.81 0.40 0.72 1.26 0.64 2.30 0.97
Makoholi
in 1990-1991:
13.54 12.00 11.93 11.89 11.55 11.49 11.45 10.61 10.58 10.44 9.80 9.02 8.99 8.98 8.56 8.03 7.70 7.40 6.79 5.96
’ DM)
1.48 2.41 1.93 1.27 1.78 2.39 3.98 1.37 2.93 0.93 4.11 3.28 1.17 1.31 2.44 0.99 2.26 2.07 1.53 2.89 -
Makoholi
yields (t ha-
Domboshawa
Totals
fodder
esculenta subsp. paniculataa diuersifolia subsp. stenocarpa palltib leucocephala x L. diversifolia
OF1 52/87 OF1 53/88 G2137 ILCA 15090 (parent = K743) OFI 34/88 OF1 58/88 ILCA 15009 OFI 45/87 OF1 19/84 OF1 35/88 OF1 47/87 OF1 48/87 OF1 83/87 OF1 61/88 OF1 46/87 OF1 2/86 OF1 84/87
oxford/ other nos. 5.45 5.10 3.18 1.67 2.19 2.58 1.63 2.16 1.60 0.92 0.45 0.70 0.00 0.00 0.00 0.71
5.79 3.54 3.71 3.76 1.47 0.70 1.34 0.67 0.73 1.14 1.11 0.24 0.03 0.00 0.03 2.72
0.74 0.17 0.91 0.53 0.40 0.46 0.66 0.31 0.45 0.57 0.49 0.13 0.38 0.12 0.06 0.36 -
1.08 0.41 0.12 0.09
5.96 4.06 3.74 3.63 3.14 2.78 2.63 2.06
11.97 8.81 7.80
Total
4.83 3.04 0.57 5.81 6.29 2.76 1.11 10.23 1.91
-
11.83 5.03
1992-1993
1994-1995
1992-1993
1993-1994
Makoholi
Domboshawa
10.48 5.19 1.38 8.98 9.52 3.59 2.02
14.31
2.23 0.94
2.67 0.83 0.42 1.61 1.78 0.36 0.24 -
2.97 1.32 0.39 1.56 1.45 0.47 0.67 -
-
1.75 1.36
-
-
7.53
-
1.36
1.14
16.45 -
Total
-
2.72
1994-1995
1.90 -
1993-1994
species and provenances at Domboshawa and Makoholi, established in 1991-1992
aL. esculenta subsp. paniculata (OF1 52/87) is synonymous with L. pallida (Alan Pottinger, personal communication). bOffspring of CPI 85890. Source:Adapted from Dzowela and Hove, 1995.
L. salvadorensis L. shannonii subsp. magnifica L. leucocephala x L. diuersijolia L. diwrsifolia subsp. divers~olia L. shannonii subsp. rnagnifica L. diversifolia subsp. stenocarpa L. esculenta subsp. esculenta L. esculenta subsp. esculenta L. pulverulenta L. m’chodes L. diversifolia subsp. diversifolia L. trichodes L. pulverulenta LSD (P < 0.05)
L. L. L. L.
Treatments
Table 3 Fodder yields (t ha-’ DM) of new Ieucaena
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
7
showed promise were L. esculenta subsp. esculenta and L. diversifolia subsp. stenocarpa. 2.2. Planting on contour-bunds
This fodder technology assumes that the field contour-bund, which is primarily constructed for soil and water conservation, is an idle piece of land in the cropland. Thus, it can be used as an entry-point for integrating fodder production in a maize farming system (Ingram and Swift, 1989). This has the advantage of not competing for the same piece of land with crops in the inter-bund area. A trial was, therefore, set up to assess the fodder-production potential of contour-bund grown multipurpose trees. The planting configuration covered a 2-m wide bund area, in which a four-row hedge was planted at a spacing of 0.5 m X 0.5 m. Each fodder species occupied a strip 8 m long. Maize rows were planted 0.45 m away from the hedges of A. angustissima, C. calothyrsus, L. leucocephala and Napier grass (previously it was C. cajun). All fodders were side-pruned twice during the wet season and the cutting management was sequentially designed such that cutting coincided with the end of January, February, March and/or April. This cutting management was deemed necessary to minimize competition with maize and the study aimed to determine the best cutting time to take advantage of residual soil moisture and thus encourage regrowth and accumulation of dry season standing fodder. The January-February cutting times increased maize yields of the adjacent rows of maize by 15-20% compared to the March-April cuttings. The early cutting (January-February) resulted in fodder yield during the dry season of the order of 0.6-0.8 t DM ha-’ (Table 4). In the 1993-1994 season A. angustissima produced the largest amount of fodder (Table 4). The fodder yield potential of A. angustissima (837 kg DM ha-’ > was almost double that achieved by the other species. Assuming a 300-kg live-weight livestock unit consuming 10 kg DM day-’ and supplemented at the rate of 30% of its daily ration, this would give 279 feeding days or 9.3 months of supplementation. This then would supplement 3 livestock units during the most critical times of the dry season (August-October). Extending this argument, the total 1994-1995 fodder-production figures provide 1523, 1430 and 1700 supplementary feeding days from A. angustissima, C. calothyrsus and L. leucocephala respectively and thus livestock units 17, 16 and 19, respectively to be supplemented during the August-October period of the dry season.
3. Chemical composition Dzowela et al, (1995b) have shown that representative multipurpose tree fodders showing the greatest potential use in agroforestry systems in Zimbabwe, sampled at 6-12 weeks regrowths have crude protein contents ranging from 189 g kg-’ DM in F. macrophylla to 292 g kg-’ DM in A. angustissima. Acid detergent fibre (ADF) content was low in S. sesban (99 g kg-’ DM) while ADF contents in F. macrophylla
8
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) l-15
Table 4 Prunings and cut fodder yields in kg DM per running metre of contour hedge (figures in parenthesis on hectare basis)“, with trees established in 1992-1993 1993-1994
A. angustissima C. cajan Asc. Ex-Maronderab
199441995 Wet season
Dry season
1.674 (837)
7.47 (3735)
1.67 (835)
0.951(476) -
0.94 (470)
N.A.
L. leucocephala
0.824 (412) 1.121 (561)
7.33 (3665) 8.68 (4340)
1.25 (625) 1.52 (760)
LSD (P < 0.05)
0.369 (185)
1.15 (576)
ns
Napier fodder C. calothyrsus
-
aAssumption: each MPT fodder strip is 100 m long and at a 4% slope there are five-contour bunds in hectare spaced approximately 20 m apart. bC. cajan died off during the 1994 dry season due to frost damage, and was replaced by the perennial grass Pennisetum purpureum (Napier grass). Source: adapted from Dzowela and Hove (1995).
(277 g kg-’ DM) and C. cajun (255 g kg-’ DM) were the highest. Ash content ranges from 58 g kg-’ DM in F. macrophylla to 95 g kg-’ DM in S. se&an. MPTs with detectable amounts of condensed tannins were A. angustissima (10.3 g kg-’ DM), C. culothyrsus (17.9 g kg-’ DM) and F. macrophyllu (3.4 g kg-’ DM).
Condensed tannin contents were associated with poor rumen degradability (DM and N) when compared with MPTs (C. cajun, G. sepium, L. leucocephula, S. macranthu, S. sesbun) without detectable condensed tannin contents. Dzowela et al. (1995b) report that G. sepium, S. mucrunthu and S. sesbun have the lowest ADF values of all MPT fodders studied (Table 5). Similarly these same species had the lowest NDF values and especially the lowest complexity with lignin and thus, had the highest IVDMD values. Levels of soluble polyphenolics ranged from 23 to 154 g kg-’ DM in the different MPT fodders, the lowest being in G. sepium, C. cujan and the highest in C. calothyrsus. While total N ranged from 20 to 33 g kg-’ DM about 60% of this on average was bound to NDF, the highest proportion of N bound to NDF occuring in C. calothyrsus and C. cajun (90% and 82%, respectively). Leucuenu leucocephala was atypical in that only 41% of its N of 32 g kg-’ DM was bound to NDF. Thus, it would appear that the higher the proportion of NDF complexed with lignin and condensed tannins, the lower the IVDMD. An exception in the case of condensed tannins was G. sepium on which Mafongoya et al. (1996) have reported that its condensed tannins have a lower complexing capacity and therefore, result in higher rumen degradability (Dzowela et al., 1995a). Differences in chemical composition have a strong bearing on the potential use of the leguminous MPT fodders in feeding systems (Table 5). They affect palatability and intake by livestock (Table 6) both within and between species and provenances. In a study undertaken at Makoholi in 1993, Dzowela et al. (1994) found a
9
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) l-15
Table 5 Chemical composition (g kg- ’ DM) of sun-dried major multipurpose tree fodders in Zimbabwe MPT spp.
ADF
NDF
A. angustissima C. cajan C. calothyrsus F. macrophylla G. sepium L. leucocephala S. macrantha S. sesban
571 493 486 545 438 541 476 476
629 574 587 595 538 589 537 490
Mean S.D.(k)
449 168
567 43
Lignin
Soluble polyphenols
-________ 143 165 114 193
Total N
_~~__
NDF-N
~~.
IVDMD
_ ~~~~
Condensed tannins Abs ssonm g -1 NDF
~_~~
122 42 154 105
31 33 20 24
21 27 18 19
401 356 358 277
16 89 53 103
209
111
23
31
25
510
122
122
32
13
437
50
NA
NA
NA
NA
540
NA
61
112
28
21
663
16
131 41
97 47
28 5
21 5
443 123
77 67
Source: adapted from Dzowela et al. (1995).
great deal of variability among the 10 species and provenances tested. Goats consumed most of the browses on offer, rejecting only A. holosericea and C. cajun hay. On the other hand, sheep accepted only one browse species (C. calothyrsus). For the MPT browses accepted by goats intakes ranged from 52 g (A. uuriculoforks hay) to 862 g dry matter animal-’ day- ’ CL. leucocephulu cv. Hawaiian Giant) by goats. Intake of the herbaceous legume L. leucocephalu was higher than that of most browses (Table 6). Even within a genus such as Leucaenu, a great deal of variability was observed in palatability or acceptability by goats (Dzowela et al., 1994) when 10 lesser known Leucuenu species and provenances were evaluated in a cafeteria system using individually penned indigenous goats. Three L. leucocephulu lines (Hawaiian giant, Cunningham and Peru) were included as controls. Species and provenances had a significant (P < 0.05) effect on palatability with the common L. leucocephulu lines being less preferred than some of the lesser known species and provenances (Table 7). It is argued that secondary plant compounds probably influenced palatability and intake. This is particularly true when comparison in palatability is made between the L. esculentu subsp. esculentu provenances (Table 7).
4. Livestock production / performance
Browseable trees and shrubs are a more reliable feed resource than herbaceous plants as they are able to retain green foliage during the dry season and drought periods. Although browses from MPTs currently being tested for use in agroforestry have desirable concentrations of most nutrients (Dzowela et al., 1994; Dzowela et al., 1995a,b), the presence of secondary plant compounds in some
10
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
Table 6 Dry matter intake (g hd-’ day-‘) of various browses by sheep and goats Animal species
MFT Fodder spp.
Mean intake
SE.
Goats
L. leucocephala G. sepium L. pulverulenta A. angustissima F. macrophyla C. cajan (fresh) C. calothyrsus S. sesban A. auriculifomk A. holosericea C. cajan (hay)
862 699 677 494 443
88 135 117 31 8
414
47
410 224 52 0
10 20 9 0
Sheep
C. calothyrsus C. cajan (hay) C. cajan (fresh) A. holosericea
0
0
449
9
0 0
0 0
0
0
Source: adapted from Dzowela et al. (1994).
species could interfere with nutrient use efficiency. A few studies are reported which quantify animal responses to diets containing these browses under Zimbabwe farming systems. A study was undertaken by the SADC-ICRAP Agroforestry Project (Dzowela et al., 1994) using goats on a basal diet of native pasture grass hay. Levels of 110, 140, 160 and 130 g of A. angustissima, C. calothyrsus, F. macrophylla and L. leucocephala respectively or a mixture of 55 g of A. angustissima and 65 g of L. leucocephala were fed as supplements. The diets were isonitrogenous and provided 4 g N animal-’ day-‘. Animals readily consumed browse supplement (as sun-dried hay). Native grass hay intake decreased while total dry matter intake increased (P < 0.05) following supplementation with browses except A. angzkssima (Table 8). Synergistic effects were apparent between A. angustissima and L. leucocephala for both native grass pasture hay intake and total dry matter intake. Browse supplementation resulted in higher (P < 0.05) growth rates than animals receiving grass hay alone. Animals receiving native pasture grass hay alone lost weight throughout the feeding period while those receiving A. angustissima, F. macrophylla and L. leucocephala had similar (P > 0.05) growth rates. Animals fed C. calothyrsus and a mixture of A. angustissima and L. leucocephala grew faster 0’ < 0.05) than the rest of the animals. Acacia angustissima and L. leucocephalu behaved synergistically for animal growth rates. In situations where the leaf material is used for soil organic manuring, the pods of trees such as L. leucocephala could be used directly as feed. A study conducted to investigate this potential using goats revealed that intake of pods was low ( < 100 g hd-l d-i) and similar (P > 0.05) at both levels of supplementation (150 g and
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) l-15
11
Table I Variation among Leucaena sp. offered as whole diets to goats Species/provenances
Origin/code
Palatability indexa
Mexico, OFI 52/87
1.00
Mexico, OFI 47/87 Hawaii
1.00 0.92
Guatemala, OFI 19/84 Mexico, OFI 83/87
0.90 0.88
ILCA No. 15009
0.79
Guatemala, OF1 53/88
0.67
Mexico, OF1 45/87 USA, OFI 84/87 G2137 (parent CPI85890)
0.66 0.57 0.55
Mexico, OF1 48/87 Cunningham Peru
0.44 0.42 0.23
L. esculenta subsp.
paniculata L. esculenta subsp.
esculenta L. leucocephala (control1 L. shannonii subsp.
magnifica L. L. L. L.
pulverulenta leucocephala x diversifolia diversifolia subsp.
stenocarpa L. diversifolia subsp.
diversifolia L. pulverulenta L. pallida L. esculenta subsp.
esculenta L. leucocephala (control) L. leucocephala (control)
DM intake a Palatability index =
DM offered ’
Source: adapted from Dzowela et al. (1994).
Table 8 Dry matter (DM) intake and growth rates (g hd-’ day-‘) supplements to native pasture hay Treatments
Supplement
Hay
AA
alone Intake: native pasture hay Total DM intake Growth rate
of goats fed browses from MPTs as
386 386 -20
AA+
LL
CC
FM
S.E.D.
305 434 16
282 419 24
276 420 9
18 21 5
LL
260 363 12
299 416 20
AA, Acacia angustissima; AA + LL, Acacia angustissima -t Leucaena leucocephala; CC, Calliandra calothyrsus; FM, Flemingia macrophylla.
leucocephala;
LL, Leucaena
Source: adapted from Dzowela et al. (1994).
250 g pods day-‘). Although diets had similar (P > 0.05) effects on grass hay and total dry matter intakes, substitution was apparent at 250 g of pods per day (Table 9). The higher pod intake adversely affected both dry matter intake and average
12
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
Table 9 Intake and growth of goats receiving dry L. leucocephala pods as a supplement to rangeland grass hay Diet
Native hay alone Native hay + 150 g pods/day Native hay + 250 g pods/day S.E.D.
Intake (g kg-’ live-weight)
Daily LWG gain (g hd-’ day- ‘)
Hay
Total DM
28
28
14
30
33
49
26 2.6
30 2.5
30 12.5
Source: Dzowela et al. (1994).
daily liveweight gain. The cause of the decline is not clear although mimosine toxicity is a possibility, since these local goats lack the rumen bacteria (Synergistes jonesii) capable of detoxifying this amino acid (Jones, 1994). However, there was a significant response in live-weight gain to rangeland hay supplemented with L. leucocephala pods (Hove, unpublished data). In the Zimbabwean production system, livestock lose up to 30% of their pre-dry season live-weight in the dry season (John Mupangwa, pers. comm.). Several methods can be used to alleviate this problem. Chief among these is the use of conventional protein supplements such as Rumevite@, a commercially available supplement. Rumevite @ is intended to supply extra protein, minerals (P, Ca and S> and thus sustain live-weights during the dry season when livestock subsist on poor quality diets. The use of conventional protein supplements in the smallholder sector is limited mainly by their high costs. A cheaper source of protein supplement for this generally resource-poor farming sector is fodder from tropical leguminous trees. In order to determine their potential, a study was undertaken locally to evaluate the effect of feeding fresh L. leucocephala as a protein supplement to steers receiving a basal diet of veld grass hay fed ad libitum during a 90-day period of the dry season at Domboshawa in 1994. Eight yearling steers aged lo-months (average live-weight 139 k 3.9 kg), were assigned to two treatment groups of four steers per group based on live-weight. Each group was housed separately for the duration of the trial, from 1st September to 8th December. One group was supplemented with fresh Leucaena leaf (24.8% CP) at the rate of 0.80-1.0 kg DM animal-’ day-l, i.e 0.20-0.25 kg CP intake head-’ day-‘. The other group was supplemented with Rumevite@ lick for 1 h daily; Rumevite@ contained 34% CP made up of 30% CP from concentrate and 4% CP from urea. This was consumed at the rate of 0.17-0.20 kg CP head-’ day-‘. The live-weight gain associated with supplementation with Leucaena was 0.30 f 0.11 kg head-’ day-’ compared with only 0.14 f 0.07 kg/head day-’ with Rumevite@. Furthermore, Rumevite@-supplemented animals completed the dry season at an average live-weight of 150 kg whereas those supplemented with
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
13
Leucaena
completed at a higher live-weight of 167 kg (Fig. 1). These data established the potential of substituting Rumevite@ with a multipurpose leguminous fodder tree such as Leucaena. Taking into account the fact that Rumevite@ has to be purchased, the Leucaena can be home-grown, the only substantial cost is the labour involved with cutting and carrying the leaf to feeding pens. Labour however, during the dry season (August to November), has a very low opportunity cost as there are few farm activities at this time.
5. Discussion of role of tree fodders in feeding systems The great diversity among the different multipurpose leguminous tree fodders in Zimbabwe point to different potentials in their use as a livestock feed resource. The biophysical limit imposed by site of establishment on production is evident in
4 Weeks
6 0 of feeding
fed a basal
of veld grass
10
12
-Rumevite +Leucaena Fig. 1. Live-weight Rumevite’
changes
of steers
hay supplemented
with leucaena
or
14
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) I-15
the comparison made between the potential at Domboshawa on the one hand and Makoholi on the other. This has implications for the choice of species and provenances to be planted. The choice of a species and indeed a provenance will depend on what role that feed resource has in a feed-year-budgeting. Furthermore, it will depend on how readily acceptable the browse species is by livestock. Another implication of the biophysical constraints has to do with the management and thus in what form (fresh or hay) the feed resource is to be presented. The most abundant feed resources in Zimbabwe during the wet season are grass (native veld pastures), planted fertilized pastures (Cynodon spp.; Chloris guymu) and Napier grass fodder (Pennisetumpulpureum) or its inter-specific hybrid with P. typhoides (Syn. americunum), Bana. During this time protein contents are within the range of ll-14% of the dry matter, sufficient for modest livestock productivity (NRC, 1984). However, during the dry season, the crude protein concentration of these feed resources and especially crop residues (cereal crop stovers) could be lower than the critical level of 7% required for ruminal function (ARC, 1980; NAS, 1976). Thus, it is during this period that multipurpose leguminous tree fodders have a supplementary or substitution role for bought-in feeds (Fig. 1). The farmer may have to make decisions on how to present the supplement. For some species (e.g. C. cajun) intake is drastically reduced when presented in hay form especially to goats. Due to limitations imposed by climate (long dry season and cool winters) most of the multipurpose tree fodders would lose their foliage; thus, the need to conserve them as hay is imperative, sometime in March/April. Conservation, evens out the feed-supply to cover the most lean times of the year. It also reduces the amount of standing tree biomass likely to suffer from frost damage. Furthermore, it optimises use of the residual soil moisture for the tree coppice and regrowth much earlier (i.e. July-August as opposed to September-October) (Dzowela, unpublished data). In the context of the Zimbabwe farming systems, it is not enough to have and promote a multipurpose tree fodder on the basis of high fodder productivity alone. For instance, very high fodder yields have been realized from G. sepium at both Domboshawa and Makoholi sites, the species suffers severely from cool winters in June-July resulting in leaf loss and stem and branch die-back. Green leaf is not present in the dry season and the trees do not flower and set seed. The tree requires live stem/branches surface area for flowering and seed production, thus in frost-prone areas it cannot be sustained without seed production locally. Cullian&a culothyrsus also has a problem with seed setting though it does flower. Other factors to consider in the choice of species and indeed provenances include ease of establishment from locally produced seed, acceptability by animals (palatability), high nutrient content and the toxic effects of secondary plant compounds such as condensed tannins on animal performance and production.
Acknowledgements
The financial support of the Canadian International Development Agency (CIDA) is gratefully acknowledged, as is the logistical support of the Department of
B.H. Dzowela et al. /Animal Feed Science Technology 69 (1997) 1-15
Research and Specialist Services, Zimbabwe Research in Agroforestry (ICRAF?.
and the International
15
Centre
for
References ARC (Agricultural Research Council), 1980. The Nutrient Requirements of Ruminant Livestock. Technical review by an Agricultural Research working party. Commonwealth Agricultural Bureaux, Farnham Royal, UK, pp. 351. Clatworthy, J.N., MacLaurin, A.R., Avila, M., 1986. The possible role of forage legumes in communal area farming systems in Zimbabwe. In: Haque, I., Jutzi, S., Neate, P.J.H. (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, pp. 265-288. Davidson, S., 1987. Adopting Leucaena - achievement and a new problem. Rural Res. 134, 22-27. Devendra, C., 1989. The use of shrubs and tree fodders by ruminants. In: Shrubs and Tree Fodders for Farm Animals, Proceedings of a workshop in Denpasar, Indonesia 24-29 July 1989, IDRC, Ottawa, Canada, pp. 42-60. Dzowela, B.H., Hove, L., 1995. SADC-ICRAF Agroforestry Project, Zimbabwe, 1994-1995 Annual Report (Highlights), pp. 91. Dzowela, B.H., Hove, L., Mafongoya, P.L., 1994. SADC-ICRAF Agroforestry Project, Zimbabwe, Annual Progress Report, pp. 86. Dzowela, B.H., Hove, L., Topps, J.H., Mafongoya, P.L., 1995. Nutritional and anti-nutritional characters and rumen digestibility of dry matter and nitrogen for some multipurpose trees species with potential for agroforestry in Zimbabwe. Anim. Feed Sci. Technol. 55, 207-214. Dzowela, B.H., Hove, L., Mafongoya, P.L., 1995. Effect of drying method on chemical composition and in vitro digestibility of multipurpose tree and shrub fodders. Trop. Grass]. 29, 263-269. Ingram, J.A., Swift, M.J., 1989. Sustainability of cereal-legume inter-crops in relation to management of soil organic matter and nutrient cycling. Farm. Sys. Bull.: East. South. Afr. 4, 7-21. Ivory, D.A., 1989. Major characteristic, agronomic features and nutritional value of shrubs and tree fodders. In: Shrubs and Tree Fodders for Farming Animals. Proceedings of a workshop in Denpasar, Indonesia, 24-29 July 1989, IDRC, Ottawa, Canada, pp. 22-38. Jones, R.M, Jones, R.J., 1984. The effect of Leucaena leucocephala on liveweight gains, thyroid size and thyroxine levels of steers in south-eastern Queenland. Aust. J. Exp. Agr. Anim. Husb. 24, 4-9. Jones, R.M., 1994. The role of Leucaena in improving the productivity of grazing cattle. In: Gutteridge, R.C., Shelton, H.M. (Eds.), Forage Tree Legumes in Tropical Agriculture. CAB International Wallingford, UK pp. 216-231. Mafongoya, P.L., Nair, P.K.R., Dzowela, B.H., 1996. Nitrogen recovery by maize: 1 Effect of multipurpose tree pruning quality and method of pruning application. Submitted to Agroforestry Systems. Manyawu, G.J., Chakoma, C., Chakoma, I., Mugwagwa, E., 1994. Rumen degradation characteristics of five browse foliages. Annual Report for the Division of Livestock and Pastures, Department of Research and Specialist Services, Harare, pp. 17-19. Mills, P.F.L., 1961. Pigeon pea as a pasture legume in the high rainfall sandveld regions of Southern Rhodesia. Rhod. Agric. J. 58, 171-172. Msangi, R., Gama, B.M., Otsyina, R., 1995. Research Highlights In: SADC-ICRAF Agroforestry Research Project, Tumbi, Tabora, Tanzania, pp. 30. NAS (National Academy of Sciencewazzu), 1976. Nutrient requirements for beef cattle. National Academy of Sciences, Washington, DC. NRC (National Research Council), 1984. Nutrient requirements of beef cattle. 6th edn. (NAS: Washington, DC).