Eleven acid soil-tolerant multipurpose trees and shrubs (MPTS) were assessed for preference and palatability with mature West African Dwarf (WAD) sheep using the cafeteria method. About 500 g each of the MPTS were weighed in triplicates into plastic feeding troughs and randomly placed around the perimeter of a Panicum maximum paddock (25 m × 25 m). Five ewes averaging 25.24 ± 0.69 kg were allowed 4 h access to the browse species daily for 12 d. Dry matter intake differed (p<0.05), ranging from 0.0 g in C. calothyrsus to 70.8 g in M. barterii. The number of animal visits, time spent and number of bites per visit on the browses also differed (p<0.05). There were positive correlations between DM intake and number of visits, number of bites, time spent on each fodder browsing and the coefficient of preference. The preference of the various MPTS by animals in descending order was M. barterii > A. cordifolia > L. leucoephala > B. monandra > D. guineensis > H. madagascariensis > T. tetraptera > T. africana > A. bella > B. grandiflora > C. calothyrsus.

A feeding experiment was conducted to study the effects of supplementation with dried Gliricidia sepium leaves on dry matter (DM) intake, digestibility and nitrogen retention in sheep fed KW4 elephant grass. Four mature rams were fed elephant grass ad libitium supplemented with four levels of gliricidia leaves (0, 4, 8 and 12 gDM kg-1wt day -1) in a 4x4 Latin swuare design. Supplementation with gliricidia leaves decreased elephant grass DM intake (g DM day-1 or g DM kg-1 BW 0.75 day -1). However, the effect of supplementation of total DM intake of the rations was not significant (P>0.05). Total crude protein intake significantly (P<0.001) increased with increasing levels of gliricidia supplementation. Total DM digestibility and body weight changes were significantly (P<0.05) improved by gliricidia supplementation; with the highest digestibility coefficient (60.5) improved by gliricidia supplementation; with the highest digestibility coefficient (60.5 percent) and body weight gain (89.3 g/day) obtained at 8 g DM kg -1wt day -1. Gliricidia supplementation significantly (P<0.001) improved nitrogen intake, absorbed nitrogen and retained nitrogen but with no significant difference at 8 and 12 g DM kg -1wt day -1 level of supplementation. The highest efficiency of N retention by sheep (44.9 percent) was obtained at 8 g DM kg -1wt day -1 level of gliricidia supplementation. The results indicated that supplemention of KW4 elephant grass with small quantities of gliricidia leaves up to 8 g DM kg -1wt day -1 enhance utilisation efficiency of the total ration. Further increases in the level of gliricidia supplementation, under the conditions of this experiment, reduced the intake of elephant grass leading to substitution effects of the basal.

Two experiments evaluated variations in feed value among Calliandra calothyrsus provenances. In Experiment 1, edible forage production of four provenances were evaluated at Ibadan, southwestern Nigeria over a 2-year period in three seasons: main-wet (April-August), minor-wet (September-November) and dry (December-March). Forage samples from the main-wet and dry seasons were incubated for 6, 12, 48, 72 and 96 h in rumen-fistulated steers to estimate in sacco dry matter (DM) and nitrogen (N) degradation characteristics. In vitro gas production was estimated over 3, 6, 12, 24, 48, 72 and 96 h of incubation. In Experiment 2, DM degradation characteristics of 14 provenances of C. calothyrsus planted on an acid soil in Yaounde, Cameroon, were evaluated. Data were subjected to cluster analysis for grouping, and the 14 provenances were placed into four distinct cluster groups. Based on the potential extent of DM and, N degradation and gas production characteristics in Experiment 1, the four provenances of C. calothyrsus were classified into three forage quality groups: high (ILCA 16310), medium (ILCA 14891, ILCA 15166) and low (NFTA 896). In Experiment 2, using the extent of DM degradation as a forage quality index, C. calothyrsus provenances in cluster 3 and 4 (namely: 51/92, 11/91. 13/91, 45/92, 10/91, 15/91, 18/91, 134/91, 12/91, 62/92), were relatively higher in quality than their counterparts in clusters 1 and 2. The results suggested the existence of intra-species variation among the provenances, and confirmed earlier observations that forage quality of C. calothyrsus could be improved through provenance evaluation.

Some species of the genus Erythrina have considerable potential as forage, but information on their nutritional value is scanty. The objective of the study was to define groups of Erythrina provenances based on rumen degradation parameters for dry matter and nitrogen which would be useful in the selection of provenances for detailed nutritional or tree improvement studies. Degradation parameters (i.e. soluble fraction (a), slowly degradable fraction (b) rate of degradation (c) and extent of degradation (a+b) were estimated for twenty Erythrina provenances beloging to seven species (E. abyssinica, E. bentipoeme, E. brucei, E. burana, E. melanacantha, E. poeppigiana and E. variegata)). The data were subjected to principal component and cluster analyses for grouping, and the 20 provenances were placed into four distinct cluster groups. Provenances of E. brucei and E. abyssinica belonged to three clusters, whereas provenances of E. burana and E. variegata were confined to one cluster. Using extent of dry matter and nitrogen degradation values of 71 and 86 percent respectively, as a forage quality index, members of clusters 1 and 2 (i.e. E. abyssinica, ILCA 10606; E. brucei, ILCA 10579, 10625, 10628, 10637, 10643; E. burana 10575, 10641, 12157; E. melanacantha ILCA 10574 and E. variegata ILCA 14991 and 14994), appeared to be superior in quality to their counterparts in clusters 3 and 4. The results suggested existence of intra and inter-species variation in rumen degradation characteristics for dry matter and nitrogen within the genus Erythrina.

Sixteen rumen fistulated Ethiopian Menz type sheep were used in a completely randomized block design in experiment 1. Unchopped teff straw was fed alone or supplemented with either 100, 150 or 200 g/d of sun-dried vernonia leaves. The chemical composition of fresh, boiled, water-soaked and sun-dried vernonia and soluble carbohydrate (SC) loss by boiling were determined. In experiment 2, 25 growing Ethiopian Menz type sheep, were fed teff straw alone or supplemented with 120 g (DM) of either boiled (B) or soaked (S) fresh vernonia with or without molasses (M) (50 g). SC lost by boiling fresh vernonia for 15, 30, 45 or 60 min was determined. In experiment 1, boiling increased the nitrogen (N) concentration in vernonia but sun-drying reduced it. N bound to fibre (NDF-N) was reduced by boiling but not by soaking. SC loss increased with boiling time. Supplementation did not affect the degradation constants (a, b, PD, c) of teff straw, but DM disappearance was increased at 76 and 120 h of incubation. Intake of sun-dried vernonia was poor but increased with quantity offered. Intake and digestibilities of DM, OM and the fibre fractions were marginally higher in the supplemented diets was low due to increased faecal and urinary excretion. In experiment 2, rumen NH3-N was higher for the boiled treatments compared to the soaked treatments. Acceptability at both 2 and 4 h was highest for BM, followed by SM, B and S. Boiling for 30 min, but not soaking, enhanced the acceptability of vernonia, suggesting that a pretreatment may enhance the feed value of vernonia.

Browse is an important forage in pastoral systems, especially during dry seasons, because it is high in nitrogen and digestibility. However, browse palatability may be reduced by possible plant defenses such as tannins and physical attributes. Chemical and physical properties of 20 browse species were correlated with the feeding preference of camels, sheep and goats during wet and dry seasons in a densely wooded, semi-arid savanna. Preference was assessed by comparing relative use with abundance of browse species. Chemical components included nitrogen, available nitrogen, acid-detergent fibre, in vitro digestibility, total tannins, and condensed tannins. Physical defenses included thorns, hooks, spines, and leaf surface properties. Animal preference was negatively related to chemical and physical defense factors, positively related to N content, and unrelated to fibre and digestibility with results depending on animal species and season. Understanding the physical and chemical factors which influence browse selectivity aids in identifying promising forage resources.

Two experiments were conducted using dried leaves of Alchornea cordifolia, Ficus capensis, Manniophytum fulvum and Albizza niopoides. In Experiment 1, dry matter (DM) degradation characteristics were investigated using the in sacco nylon bag technique in West African Dwarf (WAD) sheep, WAD goats and Bunaji steers. In Experiment 2, voluntary intake of the browse forage when fed as supplements to sheep at 0,10 and 30 percent levels was measured. In Experiment 1, A. cordifolia and M. fulvum had significantly higher rapidly degradable DM fraction than A. niopoides and F. capensis. Averaged across browse species, the extent of DM degradation for sheep (58.3 percent) was significantly higher than for goat (47.7 percent) or cattle (44.1 percent). Ranking order of browse species for the extent of DM degradation was: F. capensis > A. Cordifolia = M. fulvum = A. niopoides. In Experiment 2, as the level of supplementation increased from 10 to 30 percent, voluntary intake of A. niopoides and M. fulvum increased while voluntary intake of A. cordifolia and F. capensis declined. The results suggest that dried leaves of A. niopoides and M. fulvum are more acceptable to WAD sheep than those of A. cordifolia and F. capensis.

Twenty five rumen fistulated Ethiopian Menz sheep were used in a completely randomized block design to determine roughage utilization when different types of supplements (sesbania, leucaena, cotton seed cake (CSC) and forms (fresh or dry leucaena) were fed. The chemical composition, intake, digestibility, nitrogen balance and rumen degradibility coefficients were determined. Rumen PH and ammonia-nitrogen (NH3-N) levels were estimated in samples taken at 1, 2, 3, and 6 h after feeding. There was substitution of teff straw dry matter by the supplements. Fresh leucaena effected the highest substitution. Supplementation enhanced the dry matter degradation (DD) of teff straw at 6 and 12 hours of incubation but not for the other incubation times. There were no significant differences between treatments in the degradation constants: readly soluble component (a) slowly degradable fraction, (b) potential degradability and rate of degradation (C) and for rumen NH3-N concentration, the ranking was CSC > sesbania > dry leucaena> teff straw alone. The particularly high substitution rate observed with fresh leucaena might suggest that bulkiness may be a limiting factor in the intake of low quality roughages supplemented with tree leaves. The lower DM and OM digestibilities of the supplemented diets were attributed to substrate preference by rumen cellulolytic bacteria. Excessively high levels of rumen NH3-N (328 mg/1) in the CSC diet resulted in high urinary nitrogen losses leading to low N balance. This may suggest that for the utilization of poor quality tropical roughages, moderate levels of rumen NH3-N sustained over a longer period may be needed.

Dry, dehiscent fruits of Acacia tortilis provide important fodder for pastoral livestock in dry seasons on the central Borana Plateau, fruits of A. nilotica may also be useful during drought. Information was needed on fruit yield to assess what these species could contribute to improved calf feeding systems based on local resources. Fruit production of 10 mature trees per species was measured at five sites for seven months during 1988-9(n=50 per species). Fruit yields varied according to site, season and species X site (each at P<0.001), but there was no main effect of species (P=0.13). Yields were not correlated with trunk diameter at breast height (DBH) or canopy area within or across species (P>0.05 in all cases). Yields ranged from 0 to 40 kg DM per tree overall, with an average of 5.3 kg DM per tree (or 65 g DM/m2 of canopy area). This average tree had a DBH of 26 cm and a canopy area of 81 m2. Low and highly variable fruit yields appear to constrain enhanced use of these species here. These species warrant further attention in research and development, however, given their strategic value as forage resources in pastoral systems and their ability to persist in variable environments.

Describes a recently completed collection of Gliricidia sepium germplasm in Costa Rica. Presents and describes some characteristics of the collection sites and the range of variation in some plant characteristics.