Nutritive value of Morinda lucida and its fermentation parameters in West African dwarf (WAD) sheep when fed as supplement to grass hay

Small Ruminant Research 64 (2006) 107–115

Nutritive value of Morinda lucida and its fermentation parameters in West African dwarf (WAD) sheep when fed as supplement to grass hay I.I. Osakwe a,∗ , W. Drochner b a

Department of Animal Production and Fisheries Management, Ebonyi State University, Faculty of Agriculture, PMB 053, Abakaliki, Ebonyi State, Nigeria b Institute of Animal Nutrition (450), University of Hohenheim, 70599 Stuttgart, Germany Received 1 December 2003; received in revised form 3 November 2004; accepted 11 April 2005 Available online 17 May 2005

Abstract The nutritive value of Morinda lucida leaves (Indian Morus) was evaluated using twelve 24-month-old West African dwarf (WAD) sheep (25.0 kg body weight, BW) fed Agrostis stolonifers hay. Six of the sheep were fistulated ruminally and used for rumen pH, ammonia and volatile fatty acid (VFA) determination in the rumen fluid. Dried leaves of M. lucida were offered at two levels [25 and 50% of dry matter intake (DMI), diets 2 and 3, respectively] as supplement to basal hay diet. The basal hay diet without supplement was the control diet designated diet 1. The crude protein (CP) contents of diets 1, 2 and 3 were 102, 120 and 138 g/kg, respectively, and their digestible energy (DE) intake amounted to 5.63, 5.09 and 4.94 MJ/d, respectively. In the fermentation profile trial, the pH of diet 3 was lower (P < 0.05) than the controls and diet 2. The ruminal pH dropped (P < 0.05) during feeding, reaching its lowest value 1 h after feeding stopped, and then began to increase to pre-feeding values after 5 h. The ruminal ammonia concentration of sheep fed diet 2 and the controls was higher (P < 0.05) than that of diet 3. Diet 3 showed a higher (P < 0.05) volatile fatty acid concentration compared to the controls and diet 2. There was a higher (P < 0.05) concentration of acetate and propionate in diet 3 compared to the controls and diet 2. Nitrogen intake in the supplemented groups was higher (P < 0.05) compared to the controls. However, retained N was higher (P < 0.05) in diet 3 than in diet 2. There were differences (P < 0.05) in organic matter (OM), acid detergent fibre (ADF) and ether extract (EE) digestibility with level of supplementation. A decrease (P < 0.05) of 5.6% in OM digestibility and 7.7% in ADF digestibility was observed in diet 2 compared to the controls, respectively. The energy partitioning trial showed a depression (P < 0.05) of methane energy with supplementation level. Diet 2 had a higher (P < 0.05) faecal energy loss than the controls but not with diet 3. There were no differences in retained energy and heat loss between treatments. However, the lowest heat loss observed in diet 3 could be responsible for the marginal increase in

∗

Corresponding author. Tel.: +234 43 221093/8034910687; fax: +234 43 221093. E-mail address: osakwe [email protected] (I.I. Osakwe).

0921-4488/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.smallrumres.2005.04.008

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retained energy observed in this group. This study showed that livestock farmers could offer 50% of dried M. lucida leaves as supplement to A. stolonifers hay. © 2005 Elsevier B.V. All rights reserved. Keywords: Morinda lucida; Nutritive value; Fermentation profiles; WAD sheep

1. Introduction The major cause of low productivity of livestock in sub-Saharan Africa is the prevalent shortage in quantity and quality of feed during the dry season. The dry season poses a threat for grazing ruminants in the humid tropics of West Africa (Baur et al., 1989; Reed, 1989). During this period growth rate is low and could be negative as a result of decline in both quantity and quality of forage (Butterworth, 1985). Fodder trees and shrubs, which are part of the natural vegetation are accessible to the majority of smallholder farmers and may be useful protein supplements (Otsyina and McKell, 1985). The species used for feed (leaves and fruits, primarily) often have additional benefits when integrated into farming systems. These benefits include fuel and timber, increased soil fertility (leguminous species), control of wind erosion, shade for man and livestock, folk medicine, etc. (Le Houerou, 1980). These species are referred to as multipurpose trees. Farmers use Morinda lucida as firewood and for construction of fishing equipment. When the leaves are squeezed and mixed with palm wine, it is used against malaria and high blood pressure. It should be mentioned here that the WAD sheep and goats are the most common ruminant species found in humid zone of West Africa and raised exclusively for meat, providing a flexible financial reserve for the rural population and playing important social and cultural roles. Preliminary screening of some of these browse trees (Rittner, 1992; Larbi et al., 1993; Osakwe et al., 1999) indicated that some are less suitable as protein supplement for small ruminants than might be expected from their high crude protein (CP) content because of their high tannin contents. Min et al. (2003) reviewed the effect of condensed tannins (CT) on the nutrition and health of ruminants fed fresh temperate forages, while McNeill et al. (1998) reported that CT in the tropical legume Leucaena leucocephala increased the flow of undegraded dietary protein out of the rumen.

Nevertheless, there is dearth of information on the fermentation profile and nutritive value of some tropical multipurpose trees as supplemental diet to small ruminants. Consequently, fresh impetus is being given to the exploitation of a useful species of multipurpose trees such as M. lucida. Therefore, the objective of this study was to determine the nutritive value of M. lucida and its fermentation parameters in WAD sheep when fed as supplement to a basal hay diet.

2. Materials and methods 2.1. Feed description and preparation M. lucida is a medium-sized tree, (about 20 m high and 90 cm in girth) which grows on fallow. Fresh leaves from mature M. lucida, a tree of the Rubiaceae family, were collected in the months of November/December from Cotonou/Benin. The leaves were sun dried on raised wooden platform, then packed in plastic containers and transported to the University of Hohenheim, Germany, for analysis and feeding trial. The hay consisted primarily of cool-season grasses harvested in mid-October at the Hohenheim University using the mower. The grass was left to wilt and dry partially before a baler attached to a tractor picked up the hay and baled it. The hay was predominantly Redtop Bend grass (Agrostis stolonifers). 2.2. Experiment 1 Twelve WAD sheep of Cameroon origin, all castrates and about 24 months of age, weighing 25 ± 2.2 kg were used in a completely randomised design with three treatments and four animal replicates per treatment. Dried leaves of M. lucida were offered as supplement at two levels (25 and 50% of DMI, diets 2 and 3, respectively) replacing hay in the basal hay diet. The basal hay diet was the control, designated

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diet 1. Sheep were offered feed on DM basis 2.5% of BW at 08:00 and 16:00 h and had free access to drinking water and mineral premix supplement (10 g/d). The sheep were adapted for 10 days to the experimental diets. This was followed by an 8-day collection period in which sheep were kept in individual metabolism cages for measurement of feed intake, and to collect faeces and urine. 2.2.1. Digestibility and nitrogen balance The feed offered and refusals for each animal were weighed and recorded daily. Samples of feed and refusals were taken daily and composited until the end of collection period, dried at 65 ◦ C for 24 h, ground through a 1 mm screen and used for chemical analysis. Daily faecal excretions were collected at 08:00 h, weighed and recorded. Aliquots (10%) of the sample from each sheep was sampled daily. A portion of daily faeces was dried for 24 h at 100 ◦ C for DM determination. The remaining faecal sample was composited for each sheep and kept in refrigeration. Urine was collected and 10% aliquot of the well-mixed sample was taken daily in labelled bottles, preserved with 2–3 ml of concentrated sulphuric acid and stored in a refrigerator. At the end of the balance trial, all the sheep from each treatment were put in pairs into the respiration chambers (constructed by the Institute of Animal Nutrition, Hohenheim University, Germany) for a 24 h (4 × 24 h) measurement of the gas exchange of carbon dioxide, methane and oxygen. The system works according to the open circuit principle. Ambient temperature in the respiration chamber was between 17 and 21 ◦ C and the relative humidity 60–70%. Gas analyses for carbon dioxide and methane were done by infrared analysis with Uras 10E (Hartmann & Braun, Frankfurt/Main, Germany). Oxygen was analysed with Magnos 16 Advance Optima System (ABB/Hartmann & Braun Analytical, Frankfurt/Main, Germany) using paramagnetic principle. 2.3. Experiment 2 Six WAD-castrated sheep (average BW 25 kg) were fistulated ruminally and used for rumen pH, ammonia and VFA determination in the strained rumen liquor. Two sheep were allocated to each of the three experimental diets (control, diets 2 and 3). The sheep were adapted for 10 days to the experimental diets. This was

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followed by a 3-day consecutive sampling of rumen liquor. Rumen liqour was taken from each animal 1 h prior to feeding, and 1, 3, 5 h after feeding directly by means of a vacuum pump with the plastic tube thrust into the rumen. Immediately after collection, pH was measured (Schott CG 840 pH-meter, Germany). The samples were then immediately freed of coarse particles by filtration through two layers of cheese cloth and centrifuged at 2500 × g for 20 min under refrigeration. For determination of ruminal ammonia, 5 ml of filtrate was diluted with 45 ml of deionised water and then 0.5 ml of 10 mol/l sodium hydroxide (NaOH) added (Cammann, 1979). The gas released was measured immediately using a gas-sensitive electrode (model 15 223 3000, Mettler Toledo, Greifensee, Switzerland). A standard solution was used for the calibration curve for an ammonia electrode as described by Cammann (1979). For the determination of VFA in ruminal fluid, 5 ml of filtrate in duplicate was vacuum distilled according to Zijlstra et al. (1977). Gas chromatography analysis was made with a Hewlett Packard 5880A series gas-chromatograph with 7671A automatic sampler. Samples were kept in a refrigerator for determinations made the same day or frozen until the following day. 2.4. Analytical procedures Dried samples of M. lucida, hay, and faeces were ground in a cutting mill to pass a 1 mm mesh sieve for chemical analysis. N content was determined by the Kjeldahl method and ash by burning at 550 ◦ C (AOAC, 1990); CP was calculated from N × 6.25. Concentration of neutral detergent fibre (NDF), acid detergent fiber (ADF), permanganate–cellulose and permanganate–lignin in both feed and faeces were determined as described by Goering and Van Soest (1970). The difference between NDF and ADF was designated as hemicellulose. Gross energy (GE) of feeds and faeces were measured by bomb calorimetry (IKA-Calorimeter, model C-4000 adiabatic, Germany) using benzoic acid as a standard. Extractable tannins were analysed as described by Makkar et al. (1993). In brief, 0.5 ml of tannin extract or a dilution of the extract with 70% acetone/water (7:3, v/v) was added to 3 ml of butanol–HCl reagent, and

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then 0.1 ml of ferric reagent was added and the mixture vortexed. The mouths of the tubes were covered tightly and placed on a heating block, adjusted to 97 ◦ C for 1 h and absorbance was measured at 550 nm. Total extractable phenol and tannin phenol were analysed as described by Singleton and Rossi (1965). 2.5. Statistical analysis Data on feed intake, N and energy balance were subjected to analysis of variance (ANOVA), while data on fermentation parameter were subjected to multivariate analysis of variance (MANOVA), with the GLM Procedure (SAS, 1985). Effects of time and treatments and their interactions were studied. Treatment means were separated using Duncan’s Multiple Range Test (Duncan, 1955).

Table 1 Chemical composition of experimental diets (DM basis) and Morinda lucida (g/kg DM)a leaves Item

Controlb

Diet 2c

Diet 3d

Dry M. lucida

Crude protein Ash Ether extract Neutral detergent fibre Acid detergent fibre Acid detergent lignin Cellulose Hemicellulose Total phenolse Tannin phenole Condensed tanninsf (CT) Gross energy (kJ/g DM) Mineral premixg (g/day)

102 89 18 600 353 38 315 247 – – n.a. 17.9 10

120 91 20 555 348 70 278 207 06 03 02 18.3 10

138 92 23 510 343 102 241 167 12 07 04 18.7 10

173 95 27 420 333 166 167 87 23 13 07 19.5 n.a.

a

The values in each column represent duplicate assays per sample. Control diet = Agrostis stolonifers hay (100)%. c Diet 2 = 25% M. lucida + 75% A. stolonifers. d Diet 3 = 50% M. lucida + 50% A. stolonifers. e As tannic acid equivalent. f As leucocyanidin equivalent; n.a.: not applicable. g Composition/kg: Vitamin A 600,000 IU; Vitamin D 75,000 IU; 3 Vitamin E 300 mg; Zn 3,000 mg; Mn 480 mg; Co 12 mg; Se 10 mg. b

3. Results 3.1. Ruminal pH, ammonia and volatile fatty acid The chemical composition and gross energy content of M. lucida and the experimental diets are presented in Table 1. The CP and gross energy contents of M. lucida were 173 g/kg DM and 19.5 kJ/g DM, respectively. The CT concentration in M. lucida was 7 g/kg DM. The results for pH, ruminal ammonia and VFA concentration are presented in Table 2. The pH of diet 2 was higher (P = 0.02) than that in the two other diets and the pH of the control diet was higher (P = 0.02) than that of diet 3. The ruminal pH for all diets dropped significantly (P < 0.05) during feeding, reaching its lowest value 1 h after feeding stopped and then began to increase to pre-feeding values after 5 h. The ruminal ammonia concentration of sheep fed diet 2 and the controls was very much higher (P < 0.05) than that in diet 3. The ruminal ammonia concentration taken 1 h after feeding was superior (P < 0.05) to that sampled at −1, 3 and 5 h periods for all the diets. There was no difference between samples taken at −1 and 3 h. Diet 3 showed a higher (P < 0.05) VFA concentration compared to the two other diets. There was no difference in VFA concentrations of diet 2 and controls. There was higher (P < 0.05) concentration of acetate in diet 3 compared to the controls and diet 2. Diet 3 also

had a higher (P < 0.05) propionate concentration to the controls and diet 2. 3.2. N balance and energy partitioning The results for N balance and energy partitioning are summarized in Table 3. There was no difference in the N intake between diets 2 and 3. N intake in the supplemented groups was higher (P = 0.04) compared to the controls. Diet 2 had the highest absolute faecal and urinary-N losses compared to the controls and diet 3, leading to a negative N retention. The animals fed diet 3 compensated for a higher loss of faecal N with a lower loss of urinary N. Retained N in sheep fed diet 3 was higher (P = 0.03) than for sheep fed diet 2 but not different from the controls. The energy partitioning showed a depression (P = 0.001) of methane energy with the supplementation level. Diet 2 had a higher (P = 0.02) faecal energy loss than the controls. However, there was no difference in faecal energy loss between diets 2 and 3 and between diet 3 and the controls.The digestible energy (DE) of diet 2 was lower (P = 0.02) than for the controls but not different from diet 3.

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Table 2 Effect of supplementation of Morinda lucida on pH, ruminal ammonia and volatile fatty acid concentration in West African dwarf sheep Item

Time after feeding (h)

Control

Diet 2

Rumen pH

−1 1 3 5

S.E.M.

P-value

6.47 aC 6.20 cC 6.26 bcC 6.32 bC

0.04 0.05 0.04 0.05

0.02 0.01 0.004 0.03

Rumen NH3 a (mg/dl)

−1 1 3 5

20.5 bA 25.6 aA 16.5 bA 11.9 Ca

18.7 bA 29.9 aA 19.1 bA 9.8 cA

5.6 bB 7.8 aB 6.7 bB 5.1 cB

2.2 2.3 1.7 1.5

0.009 0.006 0.005 0.007

Total VFAb (mmol/l)

−1 1 3 5

76.5 bB 93.3 aB 87.6 aB 83.0 aB

66.1 bB 98.3 aB 92.2 aB 84.0 aB

91.1 bA 96.7 aB 99.6 aA 93.8 aA

3.5 2.8 1.7 2.0

0.04 0.03 0.01 0.02

Acetate (mmol/l)

−1 1 3 5

56.7 bB 63.9 aB 61.5 aB 59.6 aB

47.1 bB 65.3 aB 62.8 aB 58.8 aB

63.7 bA 64.2 bB 66.3 bA 63.7 bA

2.4 1.6 1.1 1.4

0.005 0.003 0.02 0.03

Propionate (mmol/l)

−1 1 3 5

12.8 dC 20.0 aC 17.5 bC 15.6 cC

12.3 dB 22.8 aB 19.4 bB 16.7 cB

19.3 dA 22.9 aB 23.2 bA 21.1 cA

0.84 1.1 0.73 0.57

0.01 0.007 0.04 0.02

6.69 aB 6.34 cB 6.40 bcB 6.45 bB

Diet 3

6.79 aA 6.41 cA 6.53 bcA 6.57 bA

Means in columns with common letters (a,b,c) are not (P > 0.05) different; means in rows with common letters (A,B,C) are not (P > 0.05) different. a Rumen NH = rumen ammonia. 3 b Total VFA = total volatile fatty acid.

Table 3 Effect of dried leaves of Morinda lucida supplementation on N and energy balance in West African dwarf sheep Item

Control diet

Diet 2

Diet 3

S.E.M.

P-value

Nitrogen intake (g/d) Faecal nitrogen (g/d) Urinary nitrogen (g/d) Retained nitrogen (g/d) Digestible nitrogen (g/d) Energy intake (MJ/d) Faecal energy (MJ/d) Urinary energy (MJ/d) Methane energy (MJ/d) Metabolisability ‘q’ (MJ/d) Retained energy (MJ/d) Heat loss (MJ/d) Digestible energy (MJ/d) Met energy/DE intake (MJ/d)a

8.6 b 4.1 4.4 0.12 ab 4.5 9.48 3.86 b 0.51 0.81 a 4.32 0.07 4.38 5.63 a 0.14 a

10.1 a 5.5 5.4 −0.8 b 4.6 9.75 4.70 a 0.54 0.66 b 3.89 −0.68 4.57 5.09 b 0.13 a

10.6 a 5.5 4.6 0.55 a 5.1 9.16 4.22 ab 0.48 0.49 b 3.98 0.23 3.74 4.94 ab 0.10 b

0.5 0.4 0.3 0.3 0.2 0.44 0.27 0.02 0.04 0.19 0.04 0.25 0.21 0.12

0.04 0.21 0.06 0.03 0.21 0.65 0.02 0.49 0.001 0.42 0.48 0.70 0.02 0.04

Means along the same rows with identical letters (a,b,c) are not (P > 0.05) different; MJ = megajoule; d = day. a Met energy/DE intake = methane energy/digestible energy intake.

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Table 4 Feed intake and nutrient digestibilities in sheep supplemented with dried leaves of Morinda lucida Item

Control

Diet 2

Diet 3

S.E.M.

P-value

Dry matter intake (g/d) DM intake (/kg BW) DM intake (/kg BW.75 ) Dry matter digestiblility OM intake (g/d) OM intake (/kg BW) OM intake (/kg BW.75 ) OM digestibility EE intake (g/d) EE digestibility NDF intake (g/d) NDF digestibility ADF intake (g/d) ADF digestibility

530.4 23.2 50.7 0.633 482.5 21.1 46.1 0.636 a 9.53 0.410 a 317.68 a 0.598 186.75 0.518 a

533.2 19.7 44.9 0.591 484.9 17.9 40.8 0.580 b 10.75 0.256 ab 296.99 ab 0.530 185.49 0.441 b

490.7 19.6 43.9 0.612 445.5 17.8 39.9 0.612 ab 10.93 0.111 b 252.87 b 0.547 168.47 0.452 ab

2.39 0.97 2.15 0.95 21.79 0.88 1.96 0.10 0.49 0.47 13.3 1.61 8.32 1.69

0.41 0.05 0.11 0.09 0.4 0.05 0.11 0.03 0.16 0.007 0.02 0.06 0.27 0.03

Means in the same row with common letters (a,b) do not differ (P > 0.05); ∗ P < 0.05; n.s. = not significant; DM = dry matter; OM = ogranic matter; EE = ether extract; NDF = neutral detergent fibre; ADF = acid detergent fibre; /kg BW = per kilogram body weight; /kg BW.75 = per kilogram metabolic weight.

3.3. Feed intake and nutrient digestibility The results for nutrient intake and digestibility are presented in Table 4. There was no difference (P = 0.41) in the DM intake and DM digestibility (P = 0.09) of sheep among treatments. However, DM intake per kg BW.75 showed a decreasing trend (P = 0.11) with supplementation. There were differences (P < 0.05) in organic matter (OM), acid detergent fibre (ADF), and ether extract (EE) digestibility as well as neutral detergent fibre intake with level of supplementation. The OM and ADF digestibility of sheep fed the control diet was higher (P = 0.03) than for those fed diet 2. The EE digestibility of the controls was higher (P = 0.007) compared to diet 3. NDF intake of sheep fed diet 3 was lower (P = 0.02) than for the controls but not different from those fed diet 2. 4. Discussion 4.1. Ruminal pH, ammonia and volatile fatty acid The pH dependence of tannin–protein interaction may be especially important in consideration of the role of tannins in digestibility and nutrition, since the various regions of the gastrointestinal tract have different pH values. The pH has a major effect on the complex formation of tannins and proteins. McLeod (1974) reported that condensed tannins can react and

form complexes by H-bonding with proteins. The decreased pH observed in diet 3 showed that M. lucida containing 0.7% CT/DM had significant effect upon major VFA formation during rumen carbohydrate fermentation. This led to the decrease in rumen pH observed at this level of supplementation. The ruminal ammonia concentration necessary for optimal digestion on various diets is not well defined. Rittner (1992) reported a range of 15–18 mg/dl with some browse plants, while a range of 5 mg/dl for optimum microbial protein synthesis has been reported by Satter and Slyter (1974) to 23 mg/dl by Mehrez et al. (1977). The mean ruminal ammonia concentration observed in this trial, 6.3–18.6 mg/dl, seemed to be adequate and is in agreeement with levels reported by Rittner (1992), Satter and Slyter (1974) and Osakwe et al. (1999). The high levels of polyphenols including high content of condensed tannins in diet 3 slightly reduced the degradation of protein. This reduction in the concentration of ruminal ammonia suggests that more protein may have escaped the rumen intact to allow higher digestion in the small intestine. The protective role of condensed tannins in the rumen has been reported by Barry and Manley (1986). This study showed that at the higher level of M. lucida supplementation, there was a severe decrease in ruminal ammonia concentration. McNeill et al. (1998) found that action of CT in the tropical legume L. leucocephala increased the flow of undegraded dietary

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protein out of the rumen but did not affect the efficiency of rumen microbial synthesis. This reduction in the concentration of ruminal ammonia could be attributed to the protective role of condensed tannin in the diet, an observation that is in agreement with the reports of Barry and Manley (1986) and Mangan (1988). Diet 3 had a superior total VFA content compared to diet 2 and the controls, as well as a superior acetate and propionate concentration compared to diet 2 and the controls. The higher VFA concentration of diet 3 and its lower pH compared to the controls and diet 2 is an indication of higher fermentation intensity. This is in agreement with the reports of Chiquette et al. (1988) and Osakwe et al. (2000) who found relatively slight differences in VFA concentrations after feeding with tannin containing feedstuff. However, Lohan et al. (1983) were unable to detect any influence on VFA amounts and pH of the rumen in a ration with 25% oak leaves. 4.2. N balance, nutrient digestibility and energy partitioning The higher N intake of the supplemented groups compared to the controls was a result of the relatively high CP of M. lucida. Diet 3 was compensated for the higher loss of faecal N with a lower loss of urinary N. This trend was also observed by ILCA (1988). Retained N in diet 3 was higher than in diet 2 resulting in an increase by 12.8% in N retention. It appears that plant proteins protected in the rumen by condensed tannins increased the supply of proteins entering the duodenum (Barry and Manley, 1986; Mangan, 1988). The increased N could be from non-bacterial sources (e.g. non-ammonia nitrogen, Barry, 1989; Min et al., 2003). Diet 2 had an inferior OM and ADF digestion compared to the control diet. A decrease of 5.6% in OM digestion and 7.7% in ADF digestion was observed in diet 2 compared to the controls. It has been reported that tannin may reduce cell wall digestibility by binding bacterial enzymes and/or forming indigestible complexes with cell wall carbohydrates (Barry and Manley, 1984; Barry et al., 1986; Reed, 1986). The depression in OM and ADF digestion in this study could indicate an inhibition of digestive enzymes by dietary tannins. This observation is consistent with several reports (Griffiths and Jones, 1977; Kumar, 1992).

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The energy partitioning showed that a significant depression of methane energy was observed in the supplemental group compared to the control group. At the higher level of supplementation, a 3.3% depression of methane was observed compared to the control diet. This depression of methane with supplementation led to a net energy gain in diet 3. This is rather a positive or beneficial effect of tannins in M. lucida, in the reduction of one of the major greenhouse gases responsible for global warming. The lowest heat loss by 40.8% of total energy intake was observed with diet 3, giving rise to a positive energy balance of 2.5% of energy retained as fat and protein by sheep fed diet 3. The nutritional effect of drying on tannins is still inconclusive probably as a result of differences in the chemical nature of tannins and animal physiological capabilities to handle tannins (Palmer and Schlink, 1992). D’Mello (1992) reported that drying may modify the nutritional effects of tannins. Terrill et al. (1989) observed that field-drying of Lespedeza cuneata (high tannin contents) decreased its assayable tannin concentration and this resulted in improved intake and increased N and fibre digestibility. Low-tannin L. cuneata did not show similar effects.

5. Conclusions M. lucida with a very low condensed tannin content (7 g/kg DM) had a reasonably high CP content (173 g/kg DM) for a non-leguminous browse plant. The nutrient digestibility showed that when offered as sole feed, the OM digestibility by difference was estimated to be 57% and the ME 7.8 MJ/kg DM. The trial showed that at a supplementation level of 50%, M. lucida showed a higher VFA concentration than the other treatments. The N-balance trial also confirmed that diet 3 had a higher retained N than diet 2. Diet 2 did not show from parameters measured to be intermediate between the control and diet 3. No reason could be given for this development. However, in some of the parameters measured, the differences between diets 2 and 3 and between diets 3 and the control were not significant. Although the improvements in energy retention and heat loss were only marginal (at the higher level of supplementation, 2.5 and 40.8%, respectively), the feeding of M. lucida could be justified when there is shortage of feed resources during the dry season. It was concluded that dried leaves of M. lucida could serve as

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a supplement to A. stolonifers hay at about 50% level of inclusion.

Acknowledgements The author would like to thank the Ecumenical Scholarship Programme, Germany, for sponsorship. The invaluable assistance of Dr. J. Greiling through the Special Research Programme 308, which supplied research materials from West Africa used in this study is gratefully acknowledged. The kind assistance of Dr. Girma Getachew and Dr. Herbert Steingass with reference materials is appreciated.

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