Intake and relative palatability indices of acacia species fed to sheep and goats

An experiment was conducted to determine preference intake and relative palatability indices of Acacia karroo, Acacia nilotica, Acacia tortilis, Acacia sieberiana and Acacia rhemniana in sheep and goats using a completely randomized design. The size of Experimental Farm from which the browses were harvested was 1842.75 ha. The leaf samples were randomly collected from various young trees. The samples were analysed for proximate composition, measured for intake and relative palatability indices of sheep and goats. Dry matter (DM) content ranged from 917.4 to 936.8 g/kg DM and organic matter from 822.9 to 892.2 g/kg DM. All acacia species contained crude protein content (CP) of more than 7–17% required for grazing animals. The content of neutral detergent fibre (ADF) and acid detergent fibre ranged from 372.8 to 658.1 and 150.0 to 464.6 g/kg DM, respectively and were significantly (P < 0.05) different among the species. All of the acacia species had low levels (0–5.57 g/kg DM) of condensed tannins. The intakes of all feeds except A. karroo and A. rhemniana were high in both sheep and goats. The leaves from A. sieberiana had the highest palatability indice (Pi) while those of A. rhemniana had the lowest Pi in both sheep and goats. It was concluded that there was an effect of acacia species on intake and relative palatability indices. Species A. sieberiana, A. nilotica and A. tortilis have potential as livestock fodder, based on moderate to high CP value, low ADF, low tannins, high intake and relative palatability indices.     

The effect of feeding maize husk and leucaena as mixture on the voluntary intake of the husk

The effect of feeding maize husk and leucaena as a mixture on voluntary intake of maize husk was studied over a 40-day period. Ten male goats with an average weight of 15 kg were used. The treatments were: (a) maize husk fed in a mixture with leucaena and (b) maize husk plus leucaena offered in separate troughs but at the same time. The maize husk intake and total dry matter intake for the two feeding methods were about the same. Thus total dry matter intake was not affected (P<0.05) by the method of feeding. There was also no significant difference (P<0.05) between the two methods of feeding in the digestibility values. The data were considered to indicate that there were no significant differences in the intake of maize husk when fed in a mixture withLeucaena leucocephala or when offered separately but at the same time.     

The effect of feeding maize husk and leucaena mixed or separately on the voluntary intake of the husk

The effect of feeding maize (Zea mays L.) husk and leucaena (Leucaena leucocephala) as a mixture or separately on the voluntary intake of maize husk was studied over a 40-day period. Ten male goats with an average weight of 15 kg were used. The maize husk intake and total dry matter intake for the two feeding methods was about the same. Thus, total dry matter intake was not affected (P<0.05) by the feeding method. There was also no significant difference (P<0.05) between the two feeding methods in the digestibility values. The data were considered to indicate that there were no significant differences in the intake of maize husk when fed in a mixture with leucaena or when offered separately but at the same time.     

Substituting sunflower seed-cake with Moringa oleifera leaves as a supplemental goat feed in Tanzania

Scarcity of animal feed resources, particularly during the dry season, is a major constraint to livestock production in the tropics. Animal feed supplement such as sunflower seed cake (SSC) are too expensive for most farmers. Therefore, alternative resources need to be investigated. Moringa oleifera Lam (Moringaceae) is a multipurpose tree, the leaves of which are used as animal feed in many places; but its potential as an animal feed supplement has not been documented. The effect of substituting SSC with different levels of M. oleifera (MOOL) on dry matter intake (DMI), dry matter digestibility (DMD) and growth performance of small, East African goats fed low-quality Chloris gayana hay was investigated in Morogoro-Tanzania. The supplementary treatments were different levels of MOOL, so that the proportions of MOOL to SSC were 0:100, 25:75, 75:25 and 100:0. All animals were fed with low-quality Chloris gayana hay as a basal ration. After a preliminary feeding period of 14 days, DMI data were collected for 21 days. Restricted feeding, and collection of urine and faecal samples for analysis were carried within 7 days of the preliminary period and 14 days of data collection. A significantly higher DMI and metabolisable energy intake (MEI) were observed at 75 and 100% MOOL supplementary levels. Increased replacement levels of SSC with MOOL increased the digestibility of DM (dry matter) and NDF (neutral detergent fibre). Goats fed 25 MOOL (T2) had significantly higher nitrogen retention than goats in the other treatments. The treatments were not different in terms of effect on the growth rates of the goats. The results suggest that MOOL could be used as a substitute for SSC, the conventional supplemental feed.This revised version was published online in November 2005 with corrections to the Cover Date.     

Intake,digestibility, nitrogen balance and certain rumen characteristics of Ethiopian Menz sheep fed teff straw supplemented with cotton seed cake,dry sesbania,dry leucaena or fresh leucaena

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 degradability 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 (p<0.05) the dry matter degradation (DD) of teff straw at 6 and 12 hours of incubation but not (p>0.06) for the other incubation times. There were no significant differences (p>0.05) between treatments in the degradation constants: readily soluble component (a) slowly degradable fraction, (b) potential degradability (PD=a+b) and rate of degradation (C) and for rumen NH₃-N concentration, the ranking was CSC > sesbania > dry leucaena > fresh leucaena > teff straw alone (p<0.05). 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/l) in the CSC diet resulted in high urinary nitrogen losses (r ²=0.32;p<0.001) 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.     

Potential contribution of <Emphasis Type="Italic">Quercus durata</Emphasis> and <Emphasis Type="Italic">Adenostoma fasciculatum</Emphasis> supplemented with <Emphasis Type="Italic">Medicago sativa</Emphasis> on intake and digestibility in sheep and goats

A digestion trial was conducted to estimate the potential contribution of the chaparral browse Quercus durata (leather oak) and Adenostoma fasciculatum (chamise) on intake and nutrient digestion in goats and sheep. Four wether Kiko goats (avg. wt. 22.9 kg) and four wether Targhee sheep (avg. wt. 39.6 kg) were housed in metabolism cages. Alfalfa pellets were used as a dietary supplement. Digestibility of the shrubs was measured by difference and metabolizable energy (ME) and ME intake (MEI) were calculated from digestibility and plants intake values. Oak and chamise had low crude protein (CP) content (6.5 and 4.3% DM) and high content of extractable condensed tannins (17.8 and 9.8% DM). In vitro organic matter digestibility (OMD) and ME for oak and chamise were 35.6 and 33.1% and 5.0 and 4.7 MJ/kg DM, respectively. In vivo OMD (calculated by difference with alfalfa) and MEI, for browse were greater (P < 0.01) for goats fed chamise compared to sheep. In oak, OMD was similar for both animal species but MEI was greater (P < 0.01) for goats. Greater (P < 0.05) DM and CP intakes (per kg BW^0.75) were observed for goats fed either oak or chamise compared with sheep. When an energy source was given as supplement, the potential contribution of chamise and oak to total ME requirements for maintenance was about 58.3 and 60.4% in goats and about 17.1 and 32.9% in sheep, respectively. In consequence, metabolizable energy supplied by these shrubs may not be adequate for maintenance when, during grazing, they are consumed in high proportions with other chaparral plants that may have lower nutritional value than the alfalfa supplemented in this study. Under an appropriate supplementation program, goats could be more effective than sheep to control fuel load in California chaparral, as they consume more chamise and leather oak and obtain more nutrients from them.     

Ruminal Fermentation and Nutrient Digestion in West African Dwarf (WAD) Sheep Fed Leucaena leucocephala Supplemental Diets

Dry season feeding has always posed a problem for ruminant nutrition in sub-Saharan Africa. The availability of browse plants or multi-purpose trees during this period has led to their incorporation in the farming systems. The need therefore to investigate the feeding value and fermentation profiles of WAD sheep fed grass hay with supplemental Leucaena leucocephala formed the objective of this study. Eight 18–24 months old West African Dwarf (WAD) sheep (28.8±4.2 kg body weight) were used in the study. Four of the sheep were fistulated ruminally and rumen pH, ammonia and volatile fatty acid were measured. Dried leaves of L. leucocephala were offered at two levels (25 and 50% of DMI, diets D25% and D50%, respectively) as supplement to a basal hay diet. The basal hay diet without supplement was the control diet. Diet D25% had a higher (p <0.05) ruminal ammonia concentration than the control, while diet D50% had a higher (p <0.05) total volatile fatty acid (VFA) concentration compared to both the control and D25% diets, respectively. Diet D25% had a marginal increase of 6.7% N- retention over the control diet. Organic matter digestibility (OMD) decreased (p <0.05) with level of supplementation. Animals on D50%, D25% and the control diets lost 14, 7.3 and 5%, respectively, of retained energy leading to a negative energy balance. Overall results suggest that a 25% level of supplementation with leucaena gave the best outcome even though a range of 25–50% could be fed during periods of basal diet scarcity.     

Forage potential ofErythrina abyssinica: intake,digestibility and growth rates for stall-fed sheep and goats in southern Ethiopia

Feeding value ofErythrina abyssinica leaves were evaluated with native sheep and goats at Soddo, southern Ethiopia in a 21-day digestibility and 80-day growth trial. In the digestibility trial, wilted leaves ofE. abyssinica were fedad libitum, while in the growth trial, animals were offered a basal diet ofP. purpureum with three levels (0, 500, 1000 g/head/day) ofE. abyssinica leaf. No significant (P>0.05) differences were found between sheep and goats in voluntary intakes and digestibilities of organic matter, nitrogen and neutral detergent fiber. Supplementing a basal diet ofP. purpureum with increasing levels ofE. abyssinica leaves resulted in reduced intake ofP. purpureum, but increased total organic matter intake in both species. Liveweight gains of sheep and goats increased linearly (P<0.01) with increasing levels ofE. abyssinica leaf supplementation. Sheep gained weight faster (P<0.04) than goats.Based on the results it was concluded thatE. abyssinica has high forage potential and can effectively serve as a cheap source of protein supplement for low quality diets during the dry season for resource-poor farmers with stall-fed sheep and goats.     

Species Selection for Afforestation of Sub-Standard Soil Sites with Particular Reference to Biomass Production and Soil Rehabilitation

Abstract

Performance of three, evenaged leguminous tree species (Acacia nilotica, A. auriculiformis and Pithecellobium duke) was evaluated on sodic soil sites (pH 9.6) at Biomass Research Centre, Banthra, Lucknow (north India). Species differed significantly in respect to plant survival, growth and productivity since beginning of its growth as observed at the age of five, 10 and, 15 years. Acacia nilotica had highest average girth at breast height (60.5 cm) and stand biomass (161 Mg ha^-1) in spite of its lowest plants survival after 15 years of growth. A. auriculiformis ranked next to it with 131 Mg ha^-1 productivity. Basal area ranged from 12.8 to 23 m² ha^-1 in different species. P. duke performed poorly as it had only 71 Mg ha^-1 of biomass. Average leaf area per hectare in different species ranged from4,129 m² ha^-1 to 16,090 m² ha^-1 after 15 years of growth. A. nilotica also showed superiority in respect to energy content in woody biomass (2,467 GJ ha^-1) and fuel wood value index (1694) as compared to the other two species. At the age of 15 years, litter accumulation over the soil surface resulted in marked reductions in soil pH, electrical conductivity, bulk density and sodium content, and increase in soil porosity, organic carbon and nitrogen content, particularly in the uppermost layer of the mineral soil (0-5 cm). A. nilotica exhibited greater efficiency in terms of soil amelioration followed by A. auriculiformis. The relative ranking of three species was A. nilotica > A. auriculiformis > P. duke, respectively. This indicated greater promise of A. nilotica for biomass production, energy harvest, and soil amelioration on degraded soil sites. Matching tree species to soil conditions needs serious considerations in order to expand site specific afforestation programs and to ameliorate vast tracts of degraded soil sites.     

Palatability of multipurpose tree species: effect of species and length of study on intake and relative palatability by sheep

The potential forage value and appropriate length of study on intake and relative palatability ranking of 40 multipurpose tree species (MPTs) were determined using 24 sheep blocked on live weight and age. As the MPTs had different dry matter contents, intakes were also expressed as a ratio of quantity offered (A_i/D_i). Using daily Eragrostis tef straw offer (TD) and intake (T), relative palatability indices were calculated as R_i = (A_i/D_i)/(T_i/TD_i). There was a significant (P < 0.0001) decrease in correlation of intake measured in day 1 and subsequent days (r = 0.88, 0.81 and 0.79 for days 2–4, days 5–8 and days 9–12, respectively). A similar trend was observed on corresponding palatability indices. Individual animal preference and blocking did not affect intake and palatability indices significantly (P > 0.05), however significant (P < 0.0001) tree species differences were observed. Results on linear regression, correlation coefficients, palatability ranking and standard errors of means (adjusted palatability indices) indicate that, if palatability is done to predict long-term intake of MPTs, at least 5 days are appropriate in palatability assessment for sheep. Using mean palatability index (days 2–12), the MPTs were grouped into four clusters. The MPTs such as Leucaena leucocephala and Sesbania sesban which are known to have good nutritive value had high palatability. In the same classification group, there were less known species such as Acacia venosa, A. persiciflora, A. melanoxylon, A. hockii, A. polycantha, Tamarindus indica, Chamaecytisus palmensis, Tipuana tipu, Indigofera arrecta and Atriplex nummularia. Flemingia macrophylla, Erythrina abyssinica, Acacia salicina, Acacia coriacea, Albizia schimperiana, Ceratonia siliqua, Casuarina glauca and Erythrina burana had poor palatability. These species seem to have little forage value for animals with short-term adaptation periods. Gliricida sepium and Calliandra calothyrsus although currently being used by farmers had a medium palatability ranking.     

Rumen degradation in sheep,goats and cattle and voluntary intake by sheep of four browse species

Two experiments were conducted using dried leaves ofAlchornea cordifolia, Ficus capensis, Manniophytum fulvum andAlbizza niopoides. In Experiment 1, dry matter (DM) degradation characteristics were investigated using thein 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% levels was measured. In Experiment 1,A. cordifolia andM. fulvum had significantly higher rapidly degradable DM fraction thanA. niopoides andF. capensis. Averaged across browse species, the extent of DM degradation for sheep (58.3%) was significantly higher than for goat (47.7%) or cattle (44.1%). 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%, voluntary intake ofA. niopoides andM. fulvum increased while voluntary intake ofA. cordifolia andF. capensis declined. The results suggest that dried leaves ofA. niopoides andM. fulvum are more acceptable to WAD sheep than those ofA. cordifolia andF. capensis.     

Vegetation dynamics in burnt heather-gorse shrublands under different grazing management with sheep and goats

Vegetation dynamics in previously burnt shrublands dominated by gorse (Ulex gallii) in north-west Spain were studied during 4 years under different grazing managements with sheep (Gallega breed) and goats (Cashmere or local breed). Initially (Period 1), treatments consisted of sheep or goat grazing on four plots (two replicates). After two grazing seasons, the plots were split in two and the treatments were reversed in four of the subplots; sheep were placed in subplots previously grazed by goats and vice versa (Period 2). The results from Period 1 showed that goats control the regrowth of gorse (from 19.6 to 14.2% of cover) more effectively than sheep (17.8 to 27.0% cover; P < 0.05), favouring the increase in herbaceous plants (from 21.5 to 42.1% of cover under goat grazing and from 22.1 to 26.6% under sheep grazing; P < 0.01). In Period 2, after changing treatments, there was a clear effect of the previous management (P < 0.01), conditioning the dynamics of the different plant components. Where the same animal species were maintained for 4 years, the differences between sheep or goat grazing on gorse and herbaceous plant dynamics increased (24.4% of gorse and 35.2% of herbaceous plant cover under goat grazing vs 43.8% of gorse cover and 19.1% of herbaceous plant cover under sheep grazing). Animal species change buffered the differences between sheep and goats during the second Period.     

Acacia angustissima: Its anti-nutrients constituents, toxicity and possible mechanisms to alleviate the toxicity – a short review

In most tropical countries poor nutrition limits ruminant productivity. The main feed resources include native pasture and crop residues, which are low in nitrogen (6.2-10.6 g/kg DM) and high in fibre (676-772 g/kg DM). Nutritional deficiencies of these feeds can be alleviated by supplementation with fodder trees such as Acacia angustissima, which are multipurpose, have outstanding agronomical attributes and are rich in nitrogen (33.2-40.8 g/kg DM). However, feeding A. angustissima without adaptation caused toxicity to sheep. Rats fed diets containing 20% A. angustissima died within 2-5 d. Intake and average daily gain (6.0 and 0.5 g/d) were significantly (P 0.05) reduced in rats fed a diet containing 70% acetone extract compared to the rats fed the control diet (8.8 and 3.1 g/d). Addition of polyethylene glycol (PEG) improved in-vitro gas and ammonia production from A. angustissima leaves (gas, 3.9 to 13.4 ml/100g DM; ammonia, 2.8 to 8.5 mM). PEG also increased DM intake (696 and 860 g /d) in sheep fed A. angustissima. These results suggested that tannin contributed to the negative effects of A. angustissima. Non-protein amino acids (4-N-acetyl-2, 4-diaminobutanoic acid, acetyl diaminopropionic acid, oxalyl diamino butyric, oxalyl diaminopropionic) have also been isolated from A. angustissima leaves. Feeding A. angustissima to sheep by gradually increasing levels in the diet prevented toxicity. Additionally, transfer of rumen contents from adapted to non-adapted sheep prevented toxicity of A. angustissima. These observations suggested that adaptation was at the microbial level. Current work to alleviate the toxicity of A. angustissima is therefore focused on microbial adaptation and detoxification. Tannin-tolerant bacteria have been isolated from sheep adapted to A. angustissima and free-ranging animals. Work on non-protein amino acids is underway. Overcoming the negative effects of the anti-nutritional factors in A. angustissima would not only improve livestock productivity but also result in improvement of the environment. This revised version was published online in June 2006 with corrections to the Cover Date.     

Influence of forbs and shrubs on intake,digestibility, and nitrogen and energy balance in sheep fed low-quality straw

A 4×4 Latin square experiment (Exp) was conducted using eight Debouillet yearling wethers with two wethers/cell to compare the effects of forbs and shrubs supplementation to a low-quality barley straw with alfalfa hay (ALF) supplementation in terms of nutrient digestion and balance. Diets studied in the Exp were barley straw (0.56% N) and straw plus either 42% ALF, 63% forbs (a 50:50 mixture of scarlet globemallow and leatherleaf croton) or 62% shrubs (mixture of 50% fourwing saltbush and 50% mountain mahogany). Diets containing ALF, forbs and shrubs were isonitrogenous (1.68% N). Periods of each Latin square were 15 days with total fecal and urine collections obtained on the last 5 days of each period. Dry matter intake of ALF and shrub-containing diets was similar and higher (P<0.05) than straw alone or straw plus forb diets. Nitrogen (N) retention was improved, but NDF digestibility was reduced (P<0.05), in diets containing ALF and shrubs compared with straw only. No difference in N retention among diets were detected (P>0.05) when N intake was used as a covariate. Metabolizable energy (ME) content of all the diets was similar except the shrub containing diet that was lower than the straw plus forbs or straw plus ALF but similar to the straw diet. Forbs had little influence on digestion and N utilization in the Exp presumably because of their reduced acceptability in the dried and ground form by sheep. Results suggest that native shrubs used in the study influenced intake and N utilization in a manner similar to ALF; and forbs used were similar in ME to ALF.     

Improving rumen fermentation and milk production with legume-tree fodder in the tropics

Feeding leguminous fodder that is high in protein can improve rumen fermentation parameters leading to increased digestibility and intake of low quality fibrous feeds, and hence improved animal production. The effect on dry matter (DM) degradation and rumen fermentation parameters of feeding urea or tree legume foliage (Erythrina poeppigiana or Gliricidia sepium), as protein supplements to a basal diet of Hyparrhenia rufa hay, rice bran and molasses, was studied with rumen fistulated steers (Zebu × Creole crossbreeds). In a second experiment, Jersey × Creole crossbreeds were used to determine the effect of the above three treatments on milk production. Both experiments were conducted at CATIE's experimental farm, Turrialba, Costa Rica (9°58 N; 83°31 W; 639 m above sea level; mean annual precipitation of 2600 mm; mean daily temperature 22 °C). The disappearance of hay DM in the rumen increased with time to 144 hours and potential degradation of hay DM was significantly higher (P < 0.05) for the legume diets compared to urea but there were no differences between legume species. Legume based rations resulted in total volatile fatty acid concentrations of rumen licor that were 15 to 24% higher than for urea based rations (P < 0.05). The concentration of rumen NH₃-N was highest two hours after feeding and tended to decrease in time. The urea ration resulted in significantly higher NH₃-N than the legume rations, reaching 45 mg/100 mL two hours after feeding. Milk yields did not differ (P > 0.05) when cows received either E. poeppigiana or G. sepium foliages as protein supplements (7.3 and 7.4 kg milk/cow/day, respectively) but they were superior (P < 0.05) to urea supplementation (6.7 kg milk/cow/day).     

Voluntary intake by sheep and goats ofGliricidia sepium fed in three states and at three levels of supplementation to a basal diet ofPanicum maximum

Crude protein content andin sacco dry matter (DM) loss after 72 h of incubation in West African dwarf (WAD) sheep and goats of fresh, wilted and dried leaves ofGliricidia sepium were compared. Additionally, voluntary DM intakes by WAD sheep and goats ofG. sepium leaves presented in the fresh, wilted and dried states at 10, 20 and 30% levels of supplementation were investigated in two separate experiments. The crude protein content and DM loss from dried leaves were relatively lower than fresh and wilted leaves. At all levels of supplementation, the voluntary DM intakes of fresh and wilted leaves by WAD sheep and goats were relatively higher than dried leaves. The results suggest thatG. sepium leaves should be fed either in the fresh or wilted states to WAD sheep and goats, at levels between 20 and 30% of the total daily DM allowance.     

Variation in relative palatability to sheep amongGliricidia sepium provenances

The cafeteria technique using three-year-old West African Dwarf sheep was used to determine relative palatability differences within 28 provenances ofGliricidia sepium collected from West Africa and Central America.Leucaena leucocephala andGuazuma ulmifolia were included as controls. Significant differences (P<0.05) in relative palatability index (RPI) were detected amongG. sepium provenances. Mexican ecotypes appeared to be of low relative palatability compared to those from Costa Rica. Based on their RPI, provenances were grouped into high (RPI>90%), medium (RPI 60–90%) and low (RPI<60%) preference rankings. The importance of the differences in relative palatability is discussed in relation to Gliricidia-based alley farming in the humid West African region.     

Effects of Gliricidia sepium (Jacq.) Steud and Leucaena leucocephala (Lam.) de Wit on growth and development of Imperata cylindrica (L.) Raeuschel.

Field studies carried out in a forest transition site on a tropical Alfisol in southwestern Nigeria, show that shading by gliricidia (Gliricidia sepium (Jacq.) Steud) and leucaena (Leucaena leucocephala (Lam.) de Wit) hedgerow species reduced density of speargrass (Imperata cylindrica (L.) Raeuschel) by 67% and 51%, respectively. Shoot biomass of speargrass decreased by 81% and 78% in gliricidia and leucaena hedgerows, respectively. Reduction in speargrass rhizome biomass in gliricidia plots was 96% while rhizome reduction in the leucaena plots was nearly 90%. Rhizome mortality was significantly higher in gliricidia plots than in leucaena and control plots. The bulk of rhizomes was found between 10 cm and 20 cm of soil depth but rhizome did not penetrate further than 30 cm depth in the Alfisol in which this study was carried out. Gliricidia was better than leucaena hedgerow species in suppressing speargrass.     

Effect of pre-feeding forage treatments,harvesting stage,and animal type on preference of tagasaste (<Emphasis Type="Italic">Chamaecytisus palmensis</Emphasis>)

Tagasaste (Chamaecytisus palmensis), a multipurpose fodder tree, is highly productive in the tropical highlands. The forage has high crude protein (CP) concentrations but is reported to have low intake by ruminants. This study investigated the effects of plant harvest stage and feeding management (wilted, dried and fresh) on levels of tannins in tagasaste and on preference and intake by Menz sheep and cattle fed during the dry season. The treatments were (1) fresh tagasaste, (2) wilted tagasaste, (3) dried tagasaste and (4) native hay. There were three preference experiments using sheep (20.2 ± 0.66 kg) to investigate intake under ad libitum or restricted offering of the forages, and to assess effect of harvest age (6- or 10-month regrowth age) on ad libitum intake. In two further experiments ad libitum offerings of the forages were evaluated using young steers (131.2 ± 19.6 kg) and heifers (156.3 ± 5.4 kg). The CP (201 g/kg), hydrolysable tannin (150.2 g/kg) and condensed tannin (8.97abs measured as absorbance at 550 nm wavelength/g NDF) contents of tagasaste forage were not affected by the physical treatments and harvesting stage. When fed ad libitum, sheep preferred (P < 0.01) fresh forage to wilted or dry tagasaste (24.5 vs. 22.9 and 7.9 g dry matter (DM)/kg metabolic body weight (MBW). The restricted offering increased intake of the less preferred dried form. Regrowth age (6 vs. 10 months) did not affect sheep preference. Unlike sheep, steers and heifers preferred (P < 0.01) dried tagasaste rather than the fresh or wilted forage. Animal preference and intake were affected by the preparation method of the forage, but not by regrowth age. Methods to improve intake (for cattle), effects of long-term feeding and evaluation on the subsequent effect of anti-nutritional compounds during digestion and animal performance should be further investigated.     

The effects of drying temperature on chemical composition and nutritive value of some tropical fodder shrubs

The effects of drying temperature on chemical composition and nutritive value of leaves of the shrub legumes Acacia angustissima (Miller) Kuntze, Calliandra calothyrsus Meissn and Leucaena leucocephala (Lam.) de Wit were determined in two studies in Zimbabwe. In the first study, the effects of shade-, sun- and oven-drying leaves on chemical composition and protein precipitation capacity of tannin extracts were studied. Drying method affected (P<0.01) chemical composition, with cell wall polysaccharides increasing from shade drying to oven drying. Calliandra calothyrsus leaves had the highest total phenolics, tannin phenolics and the lowest N content. About 40% of phenolics in L. leucocephala were non-tannin compared to less than 15% in A. angustissima and C. calothyrsus. Extractable proanthocyanidins and their capacity to precipitate protein were affected (P<0.01) by drying method; extracts from shade-dried leaves were 10% and 20% more reactive than extracts from sun- and oven-dried leaves, respectively. The relative degree of polymerisation of the proanthocyanidins was higher (P<0.01) for oven-dried (1.44) leaves compared to shade-dried (1.01) and sun-dried (1.00) leaves. Drying temperature influences the nutrient–polyphenolic interactions in A. angustissima, C. calothyrsus and L. leucocephala leaves and these interactions have important implications for feed evaluation protocols and for use of these leaves in ruminant feeding systems. The second study considered the effects of feeding sun-dried or fresh leaves of the three shrub legumes as supplements to native pasture hay on nutrient intake and digestion by goats. Feeding the fresh or dry leaves made no difference in terms of dry matter intake and digestion, and N digestion. This offers farmers flexibility in terms of feeding strategies, as they can feed the browse in any form that suits their farm situation. Increasing the level of C. calothyrsus in the diet increased faecal N. Nitrogen retention was lower for animals fed with C. calothyrsus compared to those fed with the other browses.