Sesbania Sesban Research Articles

Relationships between preference, rumen degradability, gas production and chemical composition of browses

The aim of this work was to assess whether degradability, gas production or chemical constituents could predict the preference of browses. Forty tropical browse species leaves with a crude protein (CP) content ranging from 79 to 307 g kg-1 DM were used for this study. The neutral detergent fibre (NDF) ranged from 220 to 694 g kg-1 DM, while acid detergent fibre (ADF) ranged from 146 to 523 g kg-1 DM. The NDF-bound nitrogen (NDFN) and ADF-bound nitrogen were particularly high in Calliandra calothyrsus, Acacia polyacantha, Sesbania sesban, Acacia venosa and Acacia hockii. High levels of tannins were observed in Acacia species especially A. dolichocephala, A. hockii, A. microbotrya and A. salicina. High levels were also observed in Flemingia macrophyla and Leucaena pallida. The browse species differed (P 0.05) times of incubation at which half of the asymptotic gas had been formed. Preference and DM intake were positively correlated (P < 0.01) to NDFN, but negatively correlated (P < 0.05) to NDF and ADF. The PD and Ag were negatively (P < 0.001) related to NDF, ADF and lignin. Total phenols (TP) and condensed tannins (CT) were negatively (P < 0.05) related to PD, ED and Ag. A positive correlation was observed between CT and NDF-bound condensed tannins (r = 0.55, P < 0.001) and, CT and TP (r = 0.40, P < 0.01). Prediction equations were poor for DM intake and preference, moderate for gas production and good for potential and effective degradabilities. The phenolic components were more related to dry matter degradation and gas production than to preference and dry matter intake. NDFN and Ag made a positive contribution to both preference and DM intake. It was concluded that chemical constitutes such as N, NDF, NDFN, ADF and lignin are essential to predict the nutritive value of browses.

Root and inorganic nitrogen distributions in sesbania fallow, natural fallow and maize fields

One hypothesis for a benefit of integrating trees with crops is that trees with deep root systems can capture and “pump up” nutrients from below the rooting zone of annual crops. Few studies have compared both root and nutrient distribution for planted trees, crops and grassland vegetation. A field study was conducted on a Kandiudalfic Eutrudox in the highlands of western Kenya to measure rooting characteristics and distribution of inorganic N and water in three land-use systems (LUS): (i) Sesbania sesban (L.) Merr. fallow, (ii) uncultivated natural weed fallow and (iii) unfertilized maize (Zea mays L.) monoculture. The maximum rooting depth was 1.2 m in the maize LUS, 2.25 m in a 13-month-old natural fallow, and > 4 m in a 15-month-old sesbania fallow. Total root length was 1.26 km m-2 for the maize LUS, 5.98 km m-2 for the natural fallow, and 4.56 km m-2 to 4 m for the sesbania fallow. Root length to 1.2 m was greater (p < 0.01) for natural fallow than for maize and sesbania fallow. A considerable portion of the sesbania root length to 4 m was in the subsoil; 47% was at 1.2 to 4 m and 31% was at 2.25 to 4 m. Deep rooting of sesbania coincided with lower soil water below 2 m in the sesbania fallow than the natural fallow. Nitrate-N, but not ammonium-N, to 4 m was affected by LUS. Total nitrate to 4 m was 199 kg N ha-1 for the maize LUS, 42 kg N ha-1 for the natural fallow and 51 kg N ha-1 for the sesbania fallow. Soil nitrate in the maize LUS was highest at 0.3 to 1.5-m depth on this Oxisol with anion sorption capacity. No such accumulation of subsoil nitrate was present under sesbania and natural fallow.

Utilization of browse supplements with varying tannin levels by Ethiopian Menz sheep: 1. Intake, digestibility and live weight changes

The effect of tannins in browse supplements on intake, digestibility and live weight changes was evaluated using sixty-six male Ethiopian Menz sheep in a 90-day trial. Teff straw (Eragrostis tef) was fed ad libitum (control diet), or supplemented with 190 g dried leaves of six Sesbania sesban accessions with increasing levels of condensed tannin (S1, S2, S3, S4, S5 and S6), lablab (Dolichos lablab), tagasaste (Chamaecytisus palmensis), leucaena (Leucaena leucocephala) and goetzei (Sesbania goetzei), in a completely randomized block design. The condensed tannins were highest in goetzei, S6, S5 and leucaena, intermediate in S4, S3, S2 and S1, and lowest in tagasaste and lablab. The forages differed significantly (P S5 > goetzei) in LWG. The digestibilities of total DM and the supplements did not differ significantly (P < 0.05) between the diets, although the neutral detergent fibre (NDF) digestibility decreased significantly (P < 0.05) with supplementation. The control diet had significantly higher NDF digestibility than the leucaena, S3, S4, S5 and S6 supplemented diets. Results have beneficial attributes at low levels in ruminants. Condensed tannins confer important advantages in ruminant nutrition with respect to the prevention of excessive degradation of protein in the rumen.

Utilization of browse supplements with varying tannin levels by Ethiopian Menz sheep: 2. Nitrogen metabolism

The effect of different condensed tannins concentrations on protein metabolism from browse supplements was investigated in a 90-day trial using sixty-six male Ethiopian Menz sheep. Teff straw (Eragrostis tef) was fed ad libitum (control diet), or supplemented with 190 g dried leaves of six Sesbania sesban accessions with increasing levels of condensed tannin (S1, S2, S3, S4, S5 and S6), lablab (Dolichos lablab), tagasaste (Chamaecytisus palmensis), leucaena (Leucaena leucocephala) and goetzei (Sesbania goetzei) in a completely randomized block design. The condensed tannins were highest in goetzei; S6, S5 and leucaena, intermediate in S4, S3, S2 and S1, and lowest in tagasaste and lablab. The supplemented animals had significantly (P S2 > S3 > S4 > S5), and an increase (P S2 > S3 > S4 > S5), and an increase in the estimated escape protein. The estimated rumen degradable protein (supplements) varied from 482 to 744 g kg-1 CP, while intestine digestible protein and the undegradable protein varied from 140 to 314 g kg-1 CP, hence the browses can supply adequate levels of rumen degradable and bypass protein.

Shade-based control of Imperata cylindrica: tree fallows and cover crops

Imperata is shade-intolerant, although little is known of the relative roles of competition for light, water and nutrients in suppressing its growth. Shading of Imperata results in reduced carbohydrate storage, reduced rhizome and tuber-bulb production, reduced shoot dry weight, increased susceptibility to competition, increased susceptibility to herbicides and decreased vigor/regeneration. Herbaceous cover crops in the genera Calapogonium, Crotoleria, Mucuna and Pueraria have been shown to effectively suppress Imperata growth and can be used to prevent and in some cases eradicate Imperata. Tree fallows with fast-growing species such as Sesbania sesban, Acacia nilotica and Leucaena leucocephala can improve soil physical and chemical properties and suppress weed growth. Forest plantations have been successfully used, particularly with the use of moderate to high tillage, weeding and fertilizer inputs to suppress Imperata growth. These plantations produce marketable wood and reclaim the site for other uses. Additional research is needed to evaluate the specific nature of competition and allelopathic effects from Imperata. Continued evaluation of tree species and provenances for Imperata suppression, forms of tillage after woody fallow crops and the constraints to adoption of cover crops and trees as Imperata control measures are also needed.

Sesbania and lablab supplementation of oat hay basal diet fed to sheep with or without maize grain

This study investigated the effects of supplementing oat hay (OH; milk stage at harvest) with 250 g (as-fed) of either lablab ( Dolichos lablab, 50% flowering at harvest) hay or sun dried leaves of sesbania ( Sesbania sesban) with or without 91 g dry matter (DM) of crushed maize grain on rumen pH and ammonia concentration (RAC), intake, degradability, rumen particle passage rate ( k1) (in Experiment 1), digestibility, microbial N synthesis and live weight gain (LWG) (in Experiment 2). A randomized complete block design with a 2 × 2 factorial structure was used in both experiments. In sacco DM and N degradabilities of the feeds were also determined in three sheep. Sesbania degraded faster and to a greater extent than lablab DM. Lablab N was more soluble than sesbania N. Maize-free diets of sesbania and lablab had similar k1 but k1 was lower ( P < 0.05) for lablab than for sesbania in the presence of maize. No other effect of forage legume by maize grain interaction was significant. Crushed maize grain induced lower ( P < 0.05) pH, tended to depress the rate of OH degradation by 23%, depressed ( P < 0.05) hay intake, increased the intake of DM ( P < 0.05) and N ( P < 0.001) and the growth rate of sheep ( P < 0.05) but had no effect on the digestibility (DM, OM, neutral detergent fibre (NDF) or N) and microbial N synthesis. Multiple regression analysis indicated pH ( P < 0.03) but not RAC ( P > 0.05) affected the rate of OH degradation. Sesbania sustained higher ( P < 0.001) RAC, lower ( P < 0.05) potential degradability of OH and higher intakes ( P < 0.01; OH, DM and N), N digestibility ( P < 0.05), N retention ( P < 0.01) and microbial N synthesis ( P < 0.07) than lablab. Sesbania and lablab diets had similar rates of OH degradation, digestibility (DM, OM or NDF) and LWG. It was concluded that sesbania promoted higher OH intake and tended to increase ( P < 0.08) microbial N supply but had no effect on LWG. Maize grain tended to depress OH degradation rate but promoted faster LWG.

Differences inSesbania sesban Accessions in Relation to their Phenolic Concentration and HPLC Fingerprints

Phenolic concentration in the leaves from 103 different accessions of Sesbania sesban (L) Merr was determined and HPLC was used to analyse the extractable phenolics. The chromatograms were subjected to cluster analysis. Large variation was observed between accessions in the soluble phenolic and insoluble proanthocyanidin concentrations. The study further showed that the accessions could be grouped on the basis of their HPLC fingerprints. The results suggest that quantitative and qualitative selection for polyphenolics is possible. This type of information is relevant to future programs aimed at the improvement of the nutritive value in Sesbania sesban.

Root development in a Sesbania sesban fallow-maize system in Eastern Zambia

Roots of trees (Sesbania sesban) and crops (Zea mays) were quantified during two tree/crop cycles in a sequential tree — crop system at Chipata, Eastern Zambia. The experiment included one- and two-year fallows as well as fertilized and unfertilized controls. The roots of S. sesban represent a standing biomass in the soil of 3 Mg hat-1 in the top 1.5 m after two years, with 45–60% and 70–75% being in the top 25 and 50 cm respectively. S. sesban fallow improved early rooting and growth of the following maize crop. Increased soil infiltration was also observed in the two-year fallow treatment, as well as decreased bulk density and resistance to penetration in the soil. No differences between maize root parameters could be detected at tasselling, nor differences between nutrient status of the different treatments. Study results indicate that under the drought-prone conditions of Eastern Zambia, where improved soil physical conditions are important for early deep rooting of crops and access to water and nutrients, tree roots could play an important role in the fallow effect. Further studies are required to assess the relative importance of the improvement of soil chemical and physical properties.

Inoculation and phosphorus effects on Desmodium intortum and Sesbania sesban in the Ethiopian highlands

Field experiments were conducted to study the effects of inoculation and application of P on the productivity of Desmodium intortum on an Ultisol and Sesbania sesban on a Vertisol, Alfisol and Ultisol in the Ethiopian highlands. On the Vertisol, the effect of drainage by using broad-bed-and-furrow technology was also investigated. In desmodium, inoculation had no significant effect ( P > 0.05) on nodule weight, but application of P was found to be necessary for nodulation as plants did not nodulate without P fertilizer. Both inoculation and P significantly increased plant DM and N yields. Inoculation had no significant effect on nodulation, plant DM or N yields of sesbania in any soil. Probably because of previous P applications, P had no significant effect on sesbania plants grown on the Vertisol. On the Alfisol and Ultisol, sesbania responded differently to P applied in the nursery or field. On the Alfisol, P applied in the nursery increased nodule, root and shoot DM and root and shoot N yields, but P applied in the field increased only nodule DM. The reverse occurred on an Ultisol, where P applied in the nursery had no effect on sesbania, but P applied in the field increased nodule, root and shoot DM, root N yield, and root and shoot P yields. Drainage of the Vertisol increased shoot DM and N yields. It is apparent that P deficiency is an important limiting factor to the use of inoculation technology to increase legume productivity in the Ethiopian highlands.

Soil Nitrate and Water Dynamics in Sesbania Fallows, Weed Fallows, and Maize

We hypothesized that the integration of trees into agricultural land-use systems can reduce NO3 leaching and increase subsoil N utilization. A field study was conducted on a Kandiudalfic Eutrudox (Ochinga site) and a Kandic Paleustalf (Muange site) in the subhumid highlands of Kenya to measure changes in soil NO3 and water to 200-cm depth for one rainy season in four land-use systems (LUS): (i) planted tree fallow using Sesbania sesban (L.) Merr., (ii) unfertilized maize (Zea mays L.), (iii) weed fallow, and (iv) bare fallow. Subsoil (50-200 cm) NO3-N at the start of the season ranged from 58 to 87 kg ha-1 for the four LUS and two sites. In maize, subsoil NO3-N differed by <5 kg ha-1 between planting and harvest at both sites. In sesbania, subsoil NO3-N decreased by 22 kg ha-1 at both sites, whereas in weed fallow subsoil NO3-N decreased by 26 and 38 kg ha-1 at Ochinga and Muange, respectively. At both sites, subsoil water contents at the start of the season were similar in the four LUS; but at the end of the season, soil water at 100 to 200 cm was significantly lower for sesbania than for maize. Adsorption of NO3 increased with soil depth. Sorbed NO3 at 100 to 200 cm was about 60% in the Kandiudalfic Eutrudox and about 15% in the Kandic Paleustalf. Rotation of maize with either a sesbania fallow or a weed fallow can result in more effective subsoil NO3 and water utilization than maize monoculture.

Effect of doubling the amount of low quality grass hay offered and supplementation with Acacia tortilis fruits or Sesbania sesban leaves, on intake and digestibility by sheep in Tanzania

Abstract An experiment was conducted to study the effect of doubling the amount of mature Cenchrus ciliaris hay offered at supplementing with Acacia tortilis fruits or Sesbania sesban dried leaves on intake and apparent digestibility of the diets by sheep. Six treatments were formulated to constitute two levels of the basal diet, 750 g or 1500 g hay per day. Each of the two levels of the basal ration were supplemented with either A. tortilis fruits or S. sesban leaves. Eight growing sheep were used in a change-over design to measure dry matter (DM) and organic matter (OM) digestibilities and voluntary intake. The results indicate that doubling the level of feeding increased intake of DM and OM, DM digestibility and OM digestibility. This increase is probably due to the opportunity of selecting better components of the basal ration. Although there was an increase in dietary crude protein (CP) content in diet consumed, negative values for apparent CP digestibility were observed. Supplementation of mature C. ciliaris hay with the two legumes depressed intake of the basal diet with Acacia but not with Sesbania, and resulted in increased intake of the total DM, OM and CP. The differences in performance observed between the two browse species is probably partly due to levels of anti-nutritional factors, A. tortilis fruits containing more soluble phenolics than S. sesban leaves.

Intake and digestibility for sheep and goats consuming supplementary Acacia brevispica and Sesbania sesban

The effect of two East African browses, A. brevispica and S. sesban, on feed digestibility and palatability were described. The browses were fed at three levels of each in combination with vetch ( Vicia dasycarpa) and teff straw ( Eragrostis abyssinica) in a Latin Square design to sheep and goats. Teff straw had low nitrogen (N) content (0.6%), high fiber (neutral-detergent fiber (NDF) = 72%), but low lignin (5.3%) and high true digestibility (73%). A. brevispica and vetch had similar amounts of NDF (43 and 37%) but A. brevispica had twice as much lignin, therefore lower true digestibility. A. brevispica also contained proanthocyanidins, which were absent in other feeds. S. sesban had low fiber (NDF = 21%), low lignin (3%) and high true digestibility (90%). Sheep had lower refusals of browse and higher intake rates than goats. Sheep refused only diets containing A. brevispica, perhaps because of its proanthocyanidin content. Both A. brevispica and vetch hay had reduced palatability for goats, making it impossible to separate the effect of tannins from that of fiber. Although it has been suggested that tannins reduce the digestibility of feed by inhibiting rumen microbes, there seemed to be no such effect in this case because the microbial and endogenous fraction of feces (MI), was constant across diets. There was less fecal metabolic N in diets containing S. sesban, as measured by the N concentration of neutral-detergent solubles of feces, which may be best explained by the higher fiber content of A. brevispica and vetch rather than by tannins. Tannins in A. brevispica did seem to complex with feed protein as indicated by higher concentration of N in fecal NDF (NDF-N). These complexes were recovered as fecal lignin causing a large discrepancy between true and predicted digestibility and lower N digestibility.

The degradability by sheep of fruits of Acacias and leaves of Sesbania sesban and the effects of supplementation with mixtures of browses and oilseed cake on the utilization of teff (Eragrostis tef) straw

AbstractThis study was aimed at evaluating (1) the dry matter (DM) and nitrogen (N) degradabilities (by sheep) of Sesbania sesban leaves, Acacia albida (Faidhabia albida), A. siberiana and A. tortiris frazfs and (2) the effect of feeding a mixture of oilseed cake and tanniferous browses on the degradability of teff (Eragrostis tef) straw and oilseed cake and on particulate and liquid passage rates. Thirteen rumen cannulated sheep in a randomized complete-block design experiment were given teff straw ad libitum supplemented (DM per day) with 155 g oilseed cake (50: 50 mixture of noug (Guizotia abyssinica) and groundnut cake; oilseed cake diet) or with 92 g oilseed cake plus either 118 g S. sesban (sesbania diet) or 179 g A. albida fruits (albida diet). Diets were formulated to supply 10·5 g supplementary N per day.Sesbania had the highest DM washing loss, potential degradability and fastest DM degradation rate compared with the acacias. The N washing loss (g/kg) was highest for A. siberiana (500) followed by A. albida (431), A. tortilis (431) and sesbania (241). The potential N degradability (g/kg) was greater (P &lt; 0·05) for sesbania (978) than for A. albida (848), A. tortilis (865) or A. siberiana (785). The degradation rates of oilseed cake-N and teff straw-DM, particulate and liquid passage rates, basal intake and DM digestibilities were similar among diets, but organic matter intake was highest for the albida diet. At the present levels of offer, supplementation with mixtures of oilseed cake and browses does not significantly reduce rumen degradation rates of oilseed cake-N or teff straw DM.

Acacia nilotica, Acacia seyal and Sesbania sesban as supplements to tef ( Eragrostis tef) straw fed to sheep and goats

Fifteen sheep and 15 goats were fed isonitrogenous amounts (7.2g N day −1) of A. nilotica, A. seyal and S. sesban as supplements to ad libitum allowance of tef straw in a randomized block design. Sheep consumed more straw and total DM than goats fed on the same browses. Digestibility of DM and NDF were higher ( P < 0.05) in goats than in sheep. Differences between browse species in intake of straw were not observed; however apparent N digestibility, rumen ammonia, and N retention were consistently lower in animals fed A. seyal than when animals were fed A. nilotica and S. sesban. It was concluded that differences in intake between sheep and goats could be attributed to differences in retention times and hence digestibility of DM and NDF. Differences between browse species are attributed to types and levels of tannin and related polyphenols in the leaves; and their effect on N metabolism in the rumen. Use of the faecal N fractionating technique as a non-invasive method of determining N degradability in ruminants may not be applicable to high tannin feeds.

Partitioning of chloride ion in the germinating seed of two forage legumes under varied salinity and temperature regimes

Abstract Laboratory studies were conducted to investigate the partitioning of chloride (Cl) ions in the germinating seed of two forage legumes, Sesbania (Sesbania sesban) and Snail Medic (Medicago scutellata), under varied salinities and temperatures. Seeds were placed in Petri dishes containing 20 mL of saline solutions of varied electrical conductivities (0.01, 6.4, 12.2, 17.4, 22.6, 27.2, and 32.1 d/Sm) prepared with sodium chloride (NaCl). The germination temperatures were 10, 20, 30, and 40°C. Germination counts were taken every two days for eight days and the result was used to calculate germination rate index. On Day 8, seeds were separated into seed coat, cotyledon, and embryo, and analyzed separately for Cl. Generally, Cl concentration increased in the different seed components with increase in salinity and temperature. High Cl accumulation in the embryo was associated with germination failure. However, apart from the toxic effect of high embryo Cl content, high temperatures may also have a direc...

Nutritional and anti-nutritional characters and rumen degradability of dry matter and nitrogen for some multipurpose tree species with potential for agroforestry in Zimbabwe

In a preliminary study on the nutritional value of seven multipurpose trees (MPTs), currently showing potential use in agroforestry systems in Zimbabwe, crude protein values ranged from 189 g kg −1 DM in Flemingia macrophylla to 292 g kg −1 DM in Acacia angustissima. Acid detergent fibre (ADF) content was low especially in Sesbania sesban (99 g kg −1 DM), while ADF contents in Flemingia macrophylla (277 g kg −1 DM) and Cajanus cajan (255 g kg −1 DM) were the highest. The MPTs had ash contents ranging from 58 g kg −1 DM in Flemingia macrophylla and Cajanus cajan to 95 g kg −1 DM in Sesbania sesban. MPTs with detectable amounts of condensed tannins were Calliandra calothyrsus (17.9 g kg −1 DM), A. angustissima (10.3 g kg −1 DM) and Flemingia macrophylla (3.4 g kg −1 DM). These MPTs were poorly degraded in the rumen compared to the other four species. The presence of condensed tannins could lower their potential as ruminant feeds.

Non-starch polysaccharide composition and in vitro fermentability of tropical forage legumes varying in phenolic content

The fermentation kinetics of leaves of eleven tropical forage legumes varying in phenolic and condensed tannin content were investigated. The leaf samples were from Acacia cyanophylla, Chamaecytisus palmensis, Calliandra sp., Dioclea guianensis, Flemingia macrophylla, Leucaena leucocephala, Sesbania sesban, S. goetzei and three accessions of Tadehagi sp. (accession numbers 13269, 13275 and 23227). The phenolic, condensed tannin (bound condensed tannin and extractable condensed tannin) and non-starch polysaccharide (NSP ≡ to dietary fibre) contents of leaves were determined. Leaves were incubated at 39 °C with rumen micro-organisms in a habitat-simulating medium and the fermentation kinetics investigated using a pressure transducer. The NSP content of leaves both pre-and post-incubation was quantified and proportional losses of the NSP constituents calculated. The NSP content of leaves ranged from 124–252 mg g −1 dry matter, the major components in each case being cellulose-derived glucose and the uronic acids. In all samples, the most degradable NSP constituent was the uronic acids, closely followed by arabinose; cellulose-derived glucose and xylose were the least degradable NSP components. Samples ranked in terms of asymptotic gas-pool in descending order as follows: L. leucocephala = C. palmensis > D. guianensis > S. sesban > A. cyanophylla > S. goetzei > Tadehagi sp., (23227) > Tadehagi sp., (13269) > F. macrophylla > Calliandra sp. > Tadehagi sp., (13275). There were significant relationships between gas accumulation throughout the incubation and the NSP loss (NSP L) values at the end of the incubation. Moreover, the gas pool at the end of the incubation period and NSP L were significantly correlated ( r = 0.90) with a yield constant (ml gas g −1 NSP loss) of 200 ml. Furthermore, there were significant ( P ≤ 0.05) negative relationships between both gas accumulation and NSP L and the phenolic and condensed tannin content of leaves.

Effect of supplementing oat hay with lablab, sesbania, tagasaste or wheat middlings on voluntary intake, N utilization and weight gain of Ethiopian Menz sheep

This study investigated the effect of feeding oats hay alone or with 250 g of dolichos lablab ( Lablab purpureus, 50% flowering at harvest) hay, wheat middlings, leaves of sesbania ( Sesbania sesban) or tagasaste ( Chamaecytisus palmensis) on the growth of 66 Ethiopian Menz sheep and the nutrient metabolism of five sheep from each treatment. One other dietary treatment was oats straw supplemented with lablab. Sheep on the hay-lablab diet, compared with the straw-lablab diet, had higher intake (774 vs. 711 g day −1; P < 0.01), growth rate (28 vs. 18 g day −1; P < 0.1), digestibilities of DM (576 vs. 531 g kg −1; P < 0.05), OM (608 vs. 557 g kg −1; P < 0.05) and microbial N supply (6.0 vs. 4.2 g day −1; P < 0.05), but both diets had similar N retentions. Intake of oats hay tended to be depressed by supplementation, but the depression was more pronounced with lablab and tagasaste. Supplementation increased total intake (g day −1) of DM (650 vs. 758–815; P < 0.001) and OM (573 vs. 678–737; P < 0.001), microbial N supply (4.6 vs. 6.0–8.0 g day −1; P < 0.001), N retention (0.1 vs. 1.7–3.7 g day −1; P < 0.001) and growth rate (15 vs. 25–41 g day −1; P < 0.001), but not digestibility of DM and OM. Sesbania and wheat middlings, as compared with tagasaste and lablab, promoted higher intake of DM (815 and 812 vs. 758 and 774 g day −1; P < 0.05), body weight (BW) gain (35 and 41 vs. 25 and 28 g day −1; P < 0.05), but not microbial N supply. The results were discussed in relation to, and supported, the hypothesis that variation in the performance of animals given leguminous supplements may partly be ascribed to how quickly the supplement disappears from the rumen. Oat hay is a better feed than oat straw and alone could mitigate BW losses of sheep.

Degradability of forage protein supplements and their effects on the kinetics of digestion and passage

Degradability characteristics of oats hay (harvested at milk stage), oats straw, wheat middlings and forage legumes (lablab ( Lablab purpureus) hay, leaves of sesbania ( Sesbania sesban) and tagasaste ( Chamaecytisus palmensis) were evaluated in three sheep given native hay supplemented with cottonseed cake. In Trial 2, 18 fistulated male sheep were given six dietary treatments: ad libitum oats straw with 250 g (as fed) of lablab hay; ad libitum oats hay alone or supplemented with either 250 g (as fed) of lablab hay, wheat middlings (WM), sesbania or tagasaste. The effect of these diets on degradabilities of oats hay and oats straw and rumen particulate passage rate ( k1) were determined. Oats hay had higher ( P < 0.05) solubility, potential dry matter (DM) degradability and soluble nitrogen (N) (631 vs. 498 g per kg; p < 0.01) than oats straw. Oats hay DM degraded 2.3 times faster than oats straw when both were supplemented with lablab. Sheep given hay-lablab diet had a faster k1 (0.0371 vs. 0.0173 h −1; P < 0.01) and consumed more roughage (606 vs. 447 g per day; P < 0.01) than those given strawlablab diet. Sesbania had the highest potential DM degradability (921 g per kg) followed by WM (846), tagasaste (762) and lablab (706). WM (DM) degraded fastest followed in order by sesbania, lablab and tagasaste. Lablab had the highest soluble N (737 g per kg) and differed ( p < 0.001) from sesbania (298), WM (526) and tagasaste, which was negative (−38). Sesbania had the highest potential N degradability (922), followed by lablab (866), WM (849) and tagasaste (737). Supplements had similar ( P > 0.05) N degradation rates. Supplementation and type of supplement had no effect on any of the degradation characteristics of oats hay. Sheep given WM had the fastest k1 followed in order by lablab, sesbania and tagasaste. Supplementation increased the intakes of DM ( P < 0.01) and N ( P < 0.05) but not of neutral detergent fibre (NDF); but supplement types had no effect ( P > 0.05) on the intake of oats hay, total DM or NDF. It was concluded that supplementation with forage legumes had no effect on oats hay DM degradation rate but tended to enhance k1. Forage legumes that disappear fast from the rumen may induce lower substitution rates.

Natural rhizobial populations and nodulation status of woody legumes growing in diverse Kenyan conditions

The rhizobial populations and nodulation status of both indigenous (mainly Acacia species) and some introduced woody legume species were assessed under glasshouse conditions in soils collected from 12 sites located in different ecological zones of Kenya. The populations among the sites, as estimated by the MPN technique, varied from 2.3×105 cells g-1 of soil. There were some intrasite variations in population estimates depending on the trap host species, date of soil collection and the method used in sampling the soils. Nodulation in whole soil also varied across the sites with test species frequently showing higher nodulation ability in native soils. Sesbania sesban (L.) Merr. was the most prolific nodulating species while Acacia tortilis (Forsskal) Hayne was very erratic in nodulation. Nodulation of most species showed interplant and intraspecific variability within a single soil source.