Effects of phenolics in sorghum grain on its bitterness,astringency and other sensory properties

Despite the fact that condensed tannins are potentially important antioxidants, there is a general belief that tannins in sorghum confer objectionable sensory attributes. The objective of this study was to determine differences in the sensory attributes of sorghums containing different levels of total phenolic compounds. A trained sensory panel described and quantified the sensory attributes of different sorghums (condensed‐tannin containing and tannin‐free). All the sorghum cultivars were perceived as bitter and astringent. Bran infusions of tannin sorghums were perceived as darker, clearer, more bitter and more astringent than those of the tannin‐free sorghums, while those of tannin‐free sorghums were perceived as sweeter and cloudy. Sorghum whole‐grain rice from the tannin sorghums which had relatively soft endosperm texture (PAN 3860 and Ex Nola 97 GH) was perceived as dark, hard, chewy, bitter and astringent, while that from tannin‐free sorghums having relatively hard endosperm texture (Segaolane and Phofu) was perceived as soft, sweet and had a maize‐flavour. Surprisingly, the bitterness and astringency, as well as other sensory attributes of NS 5511 (tannin sorghum), were perceived as similar to PAN 8564 (tannin‐free sorghum) even though NS 5511 had more than twice the total phenol content of PAN 8564. This suggests not all condensed‐tannin containing sorghums have objectionable sensory attributes. Copyright © 2007 Society of Chemical Industry     

Improving the quality of sorghum injera by decortication and compositing with tef

Injera is an Ethiopian fermented pancake‐like bread made from cereals, with tef being preferred. Decortication and compositing with tef were evaluated as methods to improve the injera‐making quality of red tannin‐free and tannin‐containing sorghums. Both decortication and compositing improved sorghum injera quality. Concerning decortication, mechanical abrasion was found to be more effective than hand pounding because acceptable injera was obtained with lower milling loss. Good quality injera was produced at an extraction rate of 540 g kg^?1 for tannin‐containing and 830 g kg^?1 for tannin‐free sorghum. With compositing, good quality injera was produced with a 50:50 (w/w) composite of whole tannin‐containing sorghum and tef. Both processes reduced the tannin content of the flours, which appeared to relieve the inhibiting effects of tannins on the fermentation. Decortication also seemed to improve sorghum flour injera‐making quality by improving flour pasting as a result of reducing the level of interfering substances such as lipids and proteins. In contrast, the improvement brought about by compositing with tef seemed to be due to inherent differences between tef and sorghum starch granules and an increase in the water solubility index of the flour. Compositing seems to be a more useful method of improving sorghum injera quality than decorticating as it avoids the grain loss associated with decortication. Copyright © 2005 Society of Chemical Industry     

Influence of sorghum grain type on wort physico‐chemical and sensory quality in a whole‐grain and commercial enzyme mashing process

To determine the most suitable types of sorghum for whole‐grain adjunct in lager beer brewing, 14 cultivars of five different types: white tan‐plant, white non‐tan‐plant, red non‐tannin, white tannin (type II) and red tannin (type III) were evaluated. The effects of grain type on wort physico‐chemical and sensory quality with raw grain and malt plus commercial enzyme mashing were assessed. Tannin content correlated significantly and negatively with wort extract and fermentable sugars (p < 0.001) and free amino nitrogen (FAN; p < 0.1). This is attributable to inactivation of the exogenous enzymes by the tannins during the mashing process. However, the type II tannin sorghums had wort quality attributes closer to the non‐tannin sorghum types, probably owing to their relatively low tannin content (≤1%). Malting gave a great improvement in wort extract, fermentable sugars and FAN, but substantially influenced wort sensory properties in terms of higher sourness, bitterness and astringency, as well as the expected more malty flavour. Worts from raw red non‐tannin sorghums were similar to those of white tan‐plant sorghums in both physico‐chemical and sensory quality. Thus, red non‐tannin sorghums, in view of their better agronomic quality, have considerable potential as a whole‐grain adjunct in lager beer brewing. Copyright © 2013 The Institute of Brewing & Distilling     

Effect of extrusion cooking and simulated in vitro gastrointestinal digestion on condensed tannins and radical scavenging activity of type II and type III whole grain sorghum

The effect of extrusion cooking and simulated in vitro gastrointestinal digestion on proanthocyanidins in type II and III tannin sorghums was studied. Extrusion cooking was performed at different feed moisture levels (2 L h^?1, 3 L h^?1, 5 L h^?1 and 8 L h^?1), with a barrel temperature of 150 °C followed by in vitro gastrointestinal digestion. Extrusion cooked samples had lower total phenols, tannin content and radical scavenging properties than unprocessed tannin sorghum flour. For extrudates, there was progressive increase in total phenols and tannin content with increase in feed moisture. Extrusion cooked samples had increased proportion of dimers and decreased oligomers in the two tannin sorghums. Gastric and duodenal digests of the extrudates contained high proportions of monomers and dimers and some oligomeric proanthocyanidin species. Undigested porridges, gastric and duodenal digests inhibited radical‐induced oxidative DNA damage. Extruded tannin sorghum may have health‐promoting potential in relation to combating chronic diseases associated with oxidative stress.     

Application of the dual attribute time‐intensity (DATI) sensory method to the temporal measurement of bitterness and astringency in sorghum

Bitterness and astringency are attributes generally cited as the cause of tannin sorghums being unpalatable. The objective here was to determine the effect of sorghums with varying tannin content on bitterness and astringency simultaneously using dual attribute time‐intensity (DATI). A trained panel assessed bitterness and astringency of bran infusions of tannin and tannin‐free sorghums. In both sorghum types, bitterness developed and reached maximum intensity faster (T_max 22.5 s; P < 0.001) than astringency (27.9 s). The duration of the astringent sensation (D_tot 69.9 s) lasted longer than bitterness (66.3 s). Overall, the temporal parameters for bitterness distinguished infusions from tannin and tannin‐free sorghums slightly more clearly than those for astringency. The research established that, for sorghum, bitterness and astringency are related. The DATI method also revealed that panellists’ perceptions of the time course of bitterness and astringency differ.     

Investigations on winter season Sudanese sorghum cultivars: effect of sprouting on the nutritional value

Physicochemical attributes of sorghum grains of Wad Ahmed (summer season cultivar), Abu Ragaba and Abu Kunjara (winter season cultivars) were compared. Floury endosperms characterise grains of all cultivars. Grains of Abu Ragaba and Wad Ahmed are white and Abu Kunjara are coloured. Grains were sprouted for 24, 48 and 72 h and changes in nutrients, tannin, phytic acid, protein digestibility and total and extractable minerals were studied. The nutrients and antinutients contents significantly (P ≤ 0.05) varied between cultivars. High tannin characterises Abu Ragaba and Wad Ahmed. In vitro protein digestibility of the cultivars is comparable. Contents and HCl‐extractability of Ca, P and Fe are varied. Abu Ragaba had the higher HCl‐extractability of the minerals. Sprouting changed contents of the nutrients, reduced significantly (P ≤ 0.05) tannins and phytic acid and increased digestible protein in all cultivars. Reduction of tannins was the highest in Abu Ragaba. The magnitude of reduction increased as sprouting prolonged.     

Assessment of the effect of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen fermentation and methane production in vitro

BACKGROUND: Tannins added to animal diets may have a positive effect on energy and protein utilisation in the rumen. The objective of this study was to examine the impact of different sources and concentrations (20, 50, 100, 150 and 200 g kg^?1 dry matter (DM)) of condensed (acacia and quebracho) and hydrolysable (chestnut and valonea) tannins on rumen microbial fermentation in vitro. The experiment also included a negative control with no tannins (control) and a positive control with monensin (10 mg L^?1). RESULTS: In vitro gas production and total volatile fatty acid (VFA) concentration decreased as tannin concentration increased. Addition of acacia, chestnut or valonea tannins at ≥ 50 g kg^?1 or quebracho tannins at ≥ 100 g kg^?1 resulted in a decrease (up to 40%) in methane (CH₄) production compared with the control. Valonea tannins were the only tannin source that reduced (?11%) CH₄ production at 50 g kg^?1 without affecting VFA concentration. Tannin treatments reduced ammonia (NH₃) and branched‐chain VFA concentrations, indicating a reduction in ruminal protein degradation. Monensin reduced CH₄ production (?37%) and NH₃ concentration (?20%) without affecting total VFA concentration. CONCLUSION: Supplying acacia, chestnut or valonea tannins at 50 g kg^?1 has the potential to reduce CH₄ production and ruminal protein degradation with minimum detrimental effects on efficiency of ruminal fermentation. Copyright © 2012 Crown in the right of Canada. Published by John Wiley & Sons, Ltd     

Characterisation of grain quality in diverse sorghum germplasm using a Rapid Visco-Analyzer and near infrared reflectance spectroscopy

BACKGROUND: Twenty‐two diverse sorghum landraces, classified as normal and opaque types obtained from Ethiopia, were characterised for grain quality parameters using near infra‐red spectroscopy (NIRS), chemical and Rapid Visco‐Analyzer (RVA) characteristics. RESULTS: Protein content ranged from 77 to 182 g kg^?1, and starch content from 514 to 745 g kg^?1. The NIRS analysis indicated the pig faecal digestible energy range from 14.6 to 15.7 MJ kg^?1 as fed, and the ileal digestible energy range from 11.3 to 13.9 MJ kg^?1 as fed. The normal sorghums had higher digestible energy than the opaque sorghums, which exhibited lower RVA viscosities, and higher pasting temperatures and setback ratios. The RVA parameters were positively correlated with the starch content and negatively correlated with the protein content. The normal and opaque types formed two distinct groups based on principal component and cluster analyses. CONCLUSION: The landraces were different for the various grain quality parameters with some landraces displaying unique RVA and NIRS profiles. This study will guide utilisation of the sorghum landraces in plant improvement programs, and provides a basis for further studies into how starch and other constituents behave in and affect the properties of these landraces. Copyright © 2011 Society of Chemical Industry     

Intestinal function and body growth of broiler chickens on maize‐based diets supplemented with mimosa tannins and a microbial enzyme

A study was conducted to evaluate the effects of tannin (0, 5, 15, 20 and 25 g kg^?1 diet) and a microbial enzyme supplement (MES) on the feed consumption, body growth and digestive physiology of broiler chickens between hatch and 22 days of age. Feed intake, body weight and body weight gain declined (p < 0.001) with an increase in dietary tannin content. Feed conversion efficiency was increased (p < 0.001) in line with dietary tannin level, up to 15 g kg^?1 diet. There were no significant effects of dietary treatment on the protein content of pancreatic tissue or activities of pancreatic and jejunal enzymes. The ileal digestibilities of energy, protein, arginine, alanine and leucine were reduced (p < 0.001) as dietary tannin level rose to 20 g kg^?1 diet and beyond. The digestibilities of methionine and phenylalanine were also negatively affected (p < 0.01) at the highest level of dietary tannins, while phosphorus digestion was improved (p < 0.05) on diets containing tannin. Apart from an increase (p < 0.01) in the protein content of the jejunal mucosa of birds on the diet with 20 g tannin kg^?1 diet, there were no significant effects of the MES on most of the variables assessed. The results demonstrate the negative effects of tannin, especially at high levels of inclusion in the diet. However, neither tannins nor MES influenced the activities of digestive enzymes assessed, suggesting that a wider range of factors may be involved in regulating the effects of tannins on poultry. Copyright © 2004 Society of Chemical Industry     

Impact of cowpea addition on the Protein Digestibility Corrected Amino Acid Score and other protein quality parameters of traditional African foods made from non-tannin and tannin sorghum

Protein malnutrition is a problem in Africa where sorghum is a staple foodstuff. Improvement in the protein quality of traditional African sorghum (Sorghum bicolor L. Moench) foods through the addition of cowpea (Vigna unguiculata L. Walp), an indigenous African legume, was investigated. Two sorghum cultivars, a red, tannin-type (NS 5511) and a white tan-plant, non-tannin type (Orbit) were complemented with cowpea (70:30 ratio). Ugali (thick porridge), uji (fermented thin porridge) and injera (fermented flatbread) were prepared. The protein lysine scores of cowpea-complemented foods were about double the levels of sorghum-only foods. The in vitro protein digestibility of the foods increased by 13–62%. The increase in lysine and protein digestibility improvement resulted in three- and two-fold improvement in the Protein Digestibility Corrected Amino Acid Score (PDCAAS) of NS 5511, and Orbit foods, respectively. Addition of cowpea to tannin, as well as non-tannin sorghum is a viable option for improving the protein quality of a wide range of traditional African foods.     

Effects of glutinous and nonglutinous sorghums on Saccharomyces cerevisiae fermentation for Chinese liquor making

This work investigated the effect of sorghum, including Chinese glutinous (S1 and S2) and nonglutinous (S3 and S4), Canadian nonglutinous cultivars (S5 and S6), on fermentation of Saccharomyces cerevisiae MT and FJ, the representative strains for Chinese liquor fermentation with glutinous and nonglutinous sorghums as materials, respectively. S. cerevisiae MT and FJ exhibited a longer stationary phase in glutinous and nonglutinous cultivars, respectively. Fat and tannin contents in sorghums were, respectively, negatively related with ethanol and esters production by both MT and FJ. FJ produced the most amount of flavour compounds in nonglutinous cultivars, while MT showed no preference on sorghum cultivars, as it produced most flavour compounds in both S1 and S3. Moreover, sorghums showed different characteristics on flavour production. The nonglutinous cultivars S3 and S4 were correlated with most of the acids, aromatic compounds and terpenoids, while S5 and S6 were correlated with most of the esters.     

Condensed tannins in tropical fodder crops and their in vitro biological activity: Part 2

With the aim to evaluate the biological activity of purified condensed tannins of tropical forages we conducted two in vitro experiments. In the first, using a radial diffusion technique, the protein precipitation of free condensed tannins (FCT) from Manihot esculenta, leucaena leucocephala, Arachis pintoi, Guazuma ulmyfolia, Gliricidia sepium and of tannic acid on bovine serum albumin (ASB), papain, pepsin and trypsin at pH 5.0 and 6.8 was evaluated with a three‐way analysis of variance. Significant effects (P ≤ 0.05) for the tannin type, protein source, pH and their interactions were observed. Pepsin showed the highest protein precipitation (PP) at a pH of 5.0 (82.9 µg) with FCT of G ulmyfolia and the lowest (0 and 0.2 µg) of BSA with G sepium and A pintoi at pH 6.8. Experiments were then conducted using completely randomized designs in order to observe the effect of adding 0, 1.25 or 2.50 mg of FCT from M esculenta and L leucocephala to the rumen fluid‐buffer in an in vitro dry matter digestibility test (IVDMD) of Medicago sativa and Brachiaria decumbens, The IVDMD value of M sativa (757 g kg^?1) decreased with L leucocephala tannins, although with those of M esculenta it was increased (824 g kg^?1 and 871 g kg^?1, respectively) for 1.25 and 2.5 mg of FCT. The IVDMD value of B decumbens (774 g kg^?1 without tannins) diminished with any tannin and any dose (P < 0.05). We conclude that there are differences in the FCT contents of fodder crops and in their biological activity measured as the capacity to precipitate proteins, which is modified by the type of tannin, the protein and the pH. The result of an IVDMD is regulated by the type of tannin and its dose. Copyright © 2004 Society of Chemical Industry     

Content of some antinutritional factors in bean cultivars frequently consumed in Brazil

Protein content and content of some antinutrients were determined in four Vigna unguiculata (L) Walp and three Vicia faba cultivars frequently consumed in Brazil. The V. faba cultivars showed higher protein contents [26.8%–27.2% (w/w)] than the V. unguiculata cultivars [20.5%–22.5% (w/w)]. The difference was, however, not statistically significant (P ≥ 0.05). Compared with the V. unguiculata cultivars, the V. faba cultivars exhibited a significantly higher content of all antinutritional factors analysed. In V. faba, condensed tannins ranged from 1.95 to 2.87 g eq. catechin (CE) kg⁻¹, polyphenols from 4.81 to 7.21 g kg⁻¹, phytate from 12.7 to 14.3 mmol kg⁻¹, trypsin inhibitor activity from 4.12–4.38 TIU mg⁻¹ and haemagglutinating activity from 51.3 to 57.2 HU kg⁻¹; whereas in V. unguiculata, the corresponding values were determined to be 0.97–1.81 g eq. CE kg⁻¹ for condensed tannins, 5.87–6.62 g kg⁻¹ for polyphenols, 8.7–12.6 mmol kg⁻¹ for phytate, 3.09–3.56 TIU mg⁻¹ for trypsin inhibitor activity and 0.5–0.6 HU kg⁻¹ for haemagglutinating activity.     

Forage quality and tannin concentration and composition of a collection of the tropical shrub legume Flemingia macrophylla

A collection of 23 Flemingia macrophylla (Willd.) Merrill accessions of different growth habits and contrasting digestibility and one Flemingia stricta reference accession were assessed for forage quality with particular emphasis on digestibility, condensed tannin concentration and fiber content. Large differences in in vitro dry matter digestibility (IVDMD) (356 to 598 g kg^?1), content of crude protein (CP) (121 to 254 g kg^?1) and extractable condensed tannins (CT) (0 to 268 g kg^?1), protein‐binding capacity of extractable CT or astringency (1.7 to 7.9 protein‐binding entities) (PBE) and monomer composition of extractable CT were detected. IVDMD and extractable CT were negatively correlated and extractable CT was positively correlated with protein‐binding capacity. Prodelphinidin was positively and propelargonidin negatively correlated with protein‐binding capacity of extractable CT. The accessions CIAT 18438, CIAT 21083, CIAT 21090 and CIAT 22082 were superior to the most widely used accession CIAT 17403 in terms of forage quality and could be an option in production systems with acid infertile soils. In future evaluations, particular attention needs to be paid to chemical and structural features related to the composition of extractable CT and their effect on nitrogen utilization by ruminants. Copyright © 2006 Society of Chemical Industry     

Effect of Magadi soda treatment on the tannin content and in-vitro nutritive value of grain sorghums

Studies were conducted to investigate the possible use of raw Magadi soda (RMS), a sodium sesquicarbonate salt (Na₂CO₃NaHCO₃. H₂O) in the detoxification of the tannins associated with high- and low-tannin sorghum grains and to establish the relative in-vitro nutritive value of the treated grains. Treatment of grains with concentrations as low as 4 g litre^?1 of RMS for 3 days, reduced the level of the assayable tannins in the grains by 40 to 57%. This reduction was accompanied with an increase in the in-vitro digestibility of the organic matter and starch. Treatment of the hightannin sorghums increased the in-vitro protein digestibility while no increase was observed for the low-tannin sorghums. Use of solutions containing more than 37.5 and 9 g RMS litre ^?1, resulted in reduced protein digestibility of the high- and lowtannin containing sorghums, respectively.     

Interrelationships between the concentrations of total condensed tannin,free condensed tannin and lignin in Lotus sp. and their possible consequences in ruminant nutrition

Interrelationships between the concentrations of total condensed tannin (TCT), free condensed tannin (FCT) and lignin were studied to gain knowledge of how to manipulate nutritive value of fresh herbages containing condensed tannins fed to ruminants. FCT was defined as condensed tannin not bound by macerates of fresh plants, with both FCT and TCT being determined with vanillin HCl. Effects of spraying lotus with polyethylene glycol (mol. wt 3350; PEG) upon the relationship between FCT and TCT was also studied. Increasing soil nutrient and climatic stress caused large and similar increases in the concentrations of TCT and of lignin. Over the range 0–90 g kg^?1 DM, 10% of TCT in Lotus sp. was detected as FCT, with increments in TCT above 90 g kg^?1 DM being released almost entirely as FCT. PEG formed much stronger chemical bonds with condensed tannins than did plant proteins, and did not release FCT; consequently PEG application reduced the concentration of condensed tannin that was detectable with vanillin HCl. After disintegration of plant material, it is proposed that most condensed tannin is bound and co-precipitated as an insoluble complex with protein, that FCT is in equilibrium with this complex, and that bound and free tannin are indices of nutritionally beneficial and detrimental effects produced by condensed tannins in fresh forages eaten by ruminants. It was concluded that growing Lotus pedunculatus under conditions of stress leads to depressions in nutritive value through simultaneously increasing concentrations of lignin and FCT, both of which depress rumen carbohydrate digestion and voluntary intake, and that treatment with PEG offers a convenient method of separating effects due to condensed tannins from other factors influencing nutritive value.     

The nutritive value for rats of high- and low-tannin sorghums treated with magadi soda

Grain sorghums containing 1.3, 0.7 and 0.5% tannins were treated with unrefined Magadi soda (37.5 g litre^?1) for 3 days at 25°C and evaluated in a bioassay with male weanling rats. The alkaline treatment of the samples containing 1.3 and 0.7% tannins was found to significantly increase the digestibility of crude protein, crude carbohydrates and energy and to improve the biological value (BV) of the protein. Such an effect was not found for the third sorghum cultivar (0.5% tannins).     

125th Anniversary Review: The science of the tropical cereals sorghum,maize and rice in relation to lager beer brewing

Mainstream lager beer brewing using the tropical cereals sorghum, maize and rice, either as malt or as raw grain plus commercial enzymes, is becoming widespread. This review examines the differences in composition between these tropical cereals and barley and their impact on brewing processes and beer quality. All of these cereals have a starch gelatinization temperature some 10 °C higher than barley. The sorghum prolamin proteins are particularly resistant to proteolysis owing to disulphide cross‐linking involving γ‐kafirin. Unlike barley, the major endosperm cell wall components in sorghum and maize are arabinoxylans, which persist during malting. The rice cell walls also seem to contain pectic substances. Notably, certain sorghum varieties, the tannin‐type sorghums, contain considerable levels of condensed tannins (proanthocyanidins), which can substantially inhibit amylases, and probably also other brewing enzymes. Tropical cereal malts exhibit a similar complement of enzymic activities to barley malt, with the notable exception of β‐amylase, which is much lower and essentially is absent in their raw grain. Concerning beer flavour, it is probable that condensed tannins, where present in sorghum, could contribute to bitterness and astringency. The compound 2‐acetyl‐1‐pyrroline, responsible for the popcorn aroma of maize and also the major aroma compound in rice, presumably affects beer flavour. However, much more research is needed into tropical cereals and beer flavour. Other future directions should include improving hydrolysis of prolamins into free amino nitrogen, possibly using prolyl carboxypeptidases and investigating tropical cereal lines with useful novel traits such as high amylopectin, high protein digestibility and low phytate. Copyright © 2013 The Institute of Brewing & Distilling     

Potential nutritive value and tannin bioassay of selected Acacia species from Kenya

Six Acacia forage species–A. brevispica, A. elatior, A. mellifera, A. nilotica, A. senegal and A. seyal—were analysed for their chemical composition, including phenolics and rumen fermentation characteristics. In vitro gas production technique was used to study the rumen fermentation characteristics and the effect of tannins present in the browse forages on in vitro fermentation by including polyethylene glycol (PEG‐6000) in the incubation. The forages had high crude protein content (145.7–270.1 g kg^?1 DM) and low to moderate content of neutral detergent fibre (220.2–442.8 g kg^?1 DM). The forages had variable content of total extractable phenolics ranging from 18.4 to 384.2 g kg^?1 DM and total extractable tannins ranging from 7.1 to 364.8 g kg^?1 DM (tannic acid equivalent). Fractionation of the condensed tannin flavonoids showed that the delphinidin/cyanidin ratio ranged from not detected:100 to 71:29. The gas production potential ranged from 28.4 to 40.8 mL gas 0.2 g^?1 DM. The rate of gas production was highest in A. elatior and lowest in A. nilotica. Addition of PEG‐6000 increased gas production significantly (P < 0.05) in all species except A. mellifera. PEG‐6000 addition did not have any significant effect on in vitro true dry matter and organic matter degradability but decreased the partitioning factor in all the species. Gas production and degradability parameters correlated positively with the CP content and negatively with the fibre and phenolics contents. Based on chemical composition, gas production and degradability, the forages have high potential nutritive value, especially as supplements to low‐quality feeds in the tropics and particularly during the dry season. However, the presence of tannins in terms of high levels and biological antinutritive activity may limit the nutritive potential of some of the forages, such as A. seyal and A. nilotica. Copyright © 2007 Society of Chemical Industry     

Acacia saligna as a fodder tree for desert livestock and the interaction of its tannins with fibre fractions

Acacia saligna was examined as potential fodder for sheep (27.4 kg) and goats (14.8 kg) raised in arid and semi-arid areas. This leguminous tree remains green all year and can be grown in deserts using only runoff water. Phyllodes collected in March had a crude protein content of 12.5% dry matter (DM) and high tannin content (tannins as tannic acid equivalent to 11.3% and condensed tannins as leucocyanidin equivalent to 8.3% DM). DM intake was low, amounting to 0.80% and 1.05% body mass daily for sheep and goats, respectively. Sheep lost 227 g day^?1 and goats 196 g day^?1 while on this diet. Dry matter, organic matter and energy digestibilities were low in both species but were higher for goats than for sheep, and negative digestibilities were measured for acid detergent fibre (ADF) and acid detergent lignin (ADL). Metabolisable energy intake for goats was 121.9 kJ kg^?0.75 day^?1 and for sheep was 78.6 kJ kg^?0.75 day^?1. Apparent N digestibility was 17.5% and 0.9% for goats and sheep, respectively, and both species were in negative N balance of 0.25–0.30 g kg^?0.75 day^?1. Total water intake and output were higher in sheep than in goats. Extractable tannins were virtually absent in faeces in both species, however, output of condensed tannins and protein in the ADF and ADL fractions were substantially higher. This showed the presence of tannin-protein complexes in these fractions which explained the negative digestibilities of ADF and ADL. It was concluded that Acacia saligna could not be used as a sole dietary source for small ruminants because of low intake and negative nitrogen balance. This was due mainly to the high tannin content. However, the tree might have a potential as a supplementary fodder due to its high crude protein content.