Vernonia amygdalina as a supplement to teff straw (Eragrostis tef) fed to Ethiopian Menz sheep

Sixteen rumen fistulated Ethiopian Menz type sheep were used in a completely randomized block design (CRBD) 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 compositions 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 (p<0.05) at 76 and 120 h of incubation. Intake of sun-dried vernonia was poor but increased with quantity offered. Intakes and digestibilities of DM, OM and the fibre fractions were marginally higher (p<0.05) in the supplemented diets. Nitrogen balance 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.     

Performance of Zebu Steers Grazing on Western Tanzania Native Forages Supplemented with <Emphasis Type="Italic">Leucaena Leucocephala</Emphasis> Leaf Meal

Information is lacking on the potential of leguminous fodder trees such as Leucaena leucocephala as a feed resource to supplement the native forages in traditional grazing management systems in the tropics. Two studies were conducted (1) to assess traditional fodder banks’ forage nutritive potential on animal production, and (2) to investigate the effect of Leucaena leucocephala leaf meal (LLM) supplementation on growth of steers grazing standing hay basal forages in the dry season. The traditional forages had low nutritive values indicated by low mean crude protein (CP) of 23 g kg⁻¹ dry matter (DM), and high fibre contents of 717, 546 and 153 g kg⁻¹ DM for neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL), respectively. The forages were poorly degraded in sacco and had low metabolisable energy (ME) (4.2–4.6 MJ kg⁻¹ DM). Mean washing losses A, slowly degradable DM fraction, B, potential degradability, (A+B) and mean 48 h DM degradability (DMD) of grazing land forages were 70, 471, 541 and 326 g kg⁻¹ DM, respectively. In the supplementation study, 16 growing steers (160.8±0.24 kg) were randomly allocated into four groups, in a completely randomized design. Four LLM treatment diets (T1, T2, T3 and T4), with four levels: 0, 0.4, 0.6 and 0.8 kg DM for control, low, medium and high LLM levels, respectively, were randomly allocated to the animals in the four groups for 70 days (d). LLM supplementation (p<0.05) improved mean weight gain from −0.30 to 0.26 kg steer⁻¹ d⁻¹, for T1 and T4, respectively. Steers on T4 gained (p<0.05) more weight compared to the animals in T1 and T2, though there was no (p>0.05) difference in weight gains between animals on T3 and T4 (0.14 vs. 0.26 kg steer⁻¹ d⁻¹, respectively). Standing hay basal forages alone could not sustain animal productivity during dry seasons unless corrected for protein. Higher levels of LLM supplementation prevented weight losses and improved the performance of grazing steers, a management practice thought appropriate to low income pastoralists in semiarid western Tanzania.     

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.     

低磷诱导下沙棘根系形态构建和光合作用变化

以沙棘(Hippophae rhamnoides L.)实生幼苗为试材,设置正常供磷170 mg/L(HP)和低磷胁迫0.68 mg/L(LP)两种处理,采用沙培盆栽的方式,探讨了沙棘幼苗对低磷胁迫的响应,分析了沙棘幼苗生物量、根系构型及光合特性的差异.结果表明:低磷胁迫显著(P<0.05)增加了植株的根冠比,高达45...     

Intake, rumen digestion, digestibility and microbial nitrogen supply in sheep fed Cynodon nlemfuensis supplemented with Gliricidia sepium

Four Pelibuey sheep fitted with flexible rumen cannula were fed increasing levels of Gliricidia sepium foliage (gliricidia) in a 4 × 4 Latin square design. Treatments were: control, 10, 20 and 30% (dry basis) of gliricidia mixed in a basal diet of Cynodon nlemfuensis (stargrass) hay. Dry matter (DM), organic matter (OM) and crude protein (CP) intakes were linearly increased (P < 0.05) from 45.2, 40.4, 2.0 to 71.5, 63.3 and 6.8 g/kg W^0.75/d, for the control and the 30% gliricidia diet, respectively. Similarly, increments of gliricidia in the diet resulted in a linear increase in DM, OM and CP apparent disgestibilities from 43.7, 48.4 and 27.0 to 50.7, 54.7 and 57.3%, for the control and 30% gliricidia diet, respectively. There was no effect (P > 0.05) of supplementation with gliricidia on rumen dry matter digestion of stargrass. Microbial nitrogen (N) supply to the small intestine had a trend towards an increase from 4.9, for the control, to 9.6 g N/d, for the 30% diet, though it was not significant (P > 0.05). It is concluded that, gliricidia might be incorporated into low quality diets since it increases total DM intake, supplies highly degradable N to the rumen and appears to increase the microbial N supply to the small intestine of sheep. This revised version was published online in August 2006 with corrections to the Cover Date.     

Leucaena leucocephala leaf meal as supplement to diet of grazing dairy cattle in semiarid Western Tanzania

The effect of supplementation with three levels of Leucaena leucocephala leaf meal (LLM) added to a diet composed of cotton seed hulls (CSH) and maize bran (MB) on milk yield, milk composition and body weight changes of grazing lactating cows was studied in a completely randomised design. Marginal product analysis for the different levels of LLM as a substitute to cotton seed cake (CSC) was also calculated. The following treatment diets were used in the experiment: Diet 1, (control) composed of 1.8 kg DM CSH and 1.8 kg DM MB. Diet 2, 3 and 4 had an addition of 1.2, 2.0 and 2.6 kg DM of LLM respectively. Diet 5 was composed of 1.8 kg DM of CSC and 1.8 kg DM of MB. Treatments, number of lactations, farm and initial milk yields significantly (P < 0.01) influenced milk production. LLM supplementation to grazing cows significantly increased milk production, weight gain and milk composition (P > 0.05). Cows on treatment 1 achieved no significant (P < 0.05) increase in milk yield compared to cows on treatment 2, 3, 4 and 5 which attained net milk increase of 3.6, 4.1, 6.7 and 4.4 litres/cow/day respectively. There was no significant (P > 0.05) difference in net milk produced by cows on treatment 2, 3 and 5 compared to treatment 1. LLM supplementation significantly (P < 0.05) increased total solids (TS) in milk compared to that of cows under control, but there was no significant (P > 0.05) influence on milk crude protein (CP), butter fat (BF), solids not fat (SNF) and ash in all the diets. Body weight was significantly (P < 0.05) increased by LLM supplementation. Degradation coefficients of the treatment diets were high and varied significantly (P < 0.01) and had an influence on the metabolizable energy value of the treatment diets. Cows on diet 2 to 4 had a weight gain of 190.9, 101.8 and 80.9 g/cow/day respectively and cows on diet 5 attained the highest weight gain (234.5 g/cow/day). Diet 4 had the highest marginal productivity of 4.3 followed by diets 2, 3 and 1 with marginal productivities of 2.8, 0.6 and 0 respectively. It was therefore, concluded that the optimal supplementation level using LLM as a substitute for the more expensive CSC was diet 4.This revised version was published online in November 2005 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.     

Rapid detection of self-biting disease of mink by specific sequence-characterized amplified regions

Self-biting disease occurred in most farmed fur animals in the world. The mechanism and rapid detection method of this disease has not been reported. We applied bulked sergeant analysis (BSA) in combination with RAPD method to analyze a molecular genetic marker linked with self-biting trait in mink group. The molecular marker was converted into sequence-characterized amplified regions (SCAR) marker for rapid detection of this disease. A single RAPD marker A8 amplified a specific band of 263bp in self-biting minks, which was designated as SRA8-250, and non-specific band of 315bp in both self-biting and healthy minks. The sequences of the bands exhibited 75% and 88% similarity to Canis familiarizes major histocompatibility complex (MHC) class II region and Macaca mulatta MHC class I region, respectively. A SCAR marker SCAR-A8 was designed for the specific fragment SRA8-250 and validated in 30 self-biting minks and 30 healthy minks. Positive amplification of SCAR-A8 was detected in 24 self-biting minks and 12 healthy minks. χ2 test showed significant difference (p<0.01) in the detection rate between the two groups. This indicated that SRA8-250 can be used as a positive marker to detect self-biting disease in minks. Furthermore, the finding that self-biting disease links with MHC genes has significant implications for the mechanism of the disease.     

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).     

The Potential of Albizia lebbeck as a Supplementary Feed for Goats in Tanzania

Forty growing goats (20 males and 20 females) were used in a 90-day growth and intake study to evaluate the potential of Albizia lebbeck (ABC) based concentrate as compared with Gliricidia sepium (GBC), Leucaena leucocephala (LBC), and Moringa oleifera (MBC) based concentrates with cotton seed cake (CSC) as a control. The animals were fed a basal diet of maize stover and supplemented daily with 30 g/kg W^0.75 of ABC, GBC, LBC, MBC, and CSC. They were compounded so as to formulate iso-protein diets. Treatment effects were significant (p<0.05) for growth rates in that with the exception of GBC, goats on CSC exhibited significantly higher gains compared to counterparts in other treatments. The total DM intake was between 50.6 and 52.6 g/kg W^0.75/day and there were no significant (p>0.05) differences among treatments. There were significant differences (p<0.05) among treatments for maize stover intake. CSC based treatment showed the highest intake with insignificant (p>0.05) differences amongst the leaf meal based concentrates. It can be concluded that Albizia lebbeck had similar potential to the other leaf meal based supplements studied but had lower potential compared to a cotton seed cake based supplement, as protein sources for growing goats fed a poor quality basal diet.     

Gliricidia sepium as an alternative protein supplement to cottonseed cake for smallholder dairy cows fed on Napier grass in Tanzania

Lack of availability, poor quality forages and cost of concentrate feeds, especially during the dry season, are some of the major problems faced by smallholder dairy producers in the tropics. Therefore, two experiments were conducted to evaluate the nutritive value and economic benefits of substituting cottonseed cake (CSC) by Gliricidia sepium (GS) for milk yield and composition of crossbred dairy cattle. In experiment one chemical composition of the two feeds and their dry matter degradability (DMD) were determined. GS had (P < 0.05) higher dry matter degradability (DMD) than CSC. Potential DM degradability (PDMD) and degradation rate constants (c) of CSC and GS did not vary (P > 0.05). In experiment two, four treatment diets, all based on Napier grass, maize bran, mineral/vitamin mixture and two levels each of GS and CSC, were fed to milk cows in a 4 × 4 Latin square experiment. The treatments were, T1 = 0 GS + CSC 18%, T2 = 18% GS + CSC, T3 = 23.4% GS + CSC and T4 = 39.7% GS + CSC. Cows on T1 and T3 showed (P < 0.05) higher total DMI, metabolizable energy intake (MEI) and milk yield than cows on T2 and T4. There were no differences (P > 0.05) in milk protein, butterfat and total solids contents between the treatments. Cost analyses showed diet T3 to be more profitable than the other treatments, suggesting that the use of GS in combination with CSC is more profitable than when either of the two was used alone.This revised version was published online in November 2005 with corrections to the Cover Date.     

Feed value of multipurpose fodder trees and shrubs in West Africa: edible forage production and nutritive value of Millettia thonningii and Albizia lebbeck

Millettia thonningii (Schum. & Thonn.) Bak., a nitrogen fixing shrub native to Africa and Albizia lebbeck Benth, were harvested at 0.50 m above ground level after one year of establishment to determine edible forage production. Harvests were made at the end of the main (April–August) and minor (September–November) wet, and dry (December–March) seasons for two years. Dry season edible forage samples were analyzed for concentrations of crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (NDF), acid detergent lignin (ADL), cellulose (CL), soluble phenolics (SOPH) and proanthocyanidins (PAs). In sacco dry matter (DM) and nitrogen (N) degradation and in vitro gas production (GP) characteristics were also determined on dry season edible forage samples. Edible forage production of M. thonningii was significantly lower than A. lebbeck during the wet seasons. Millettia thonningii had relatively lower CP and PAs, but higher NDF, ADF, ADL, CL and SOPH than A. lebbeck. In sacco DM and N degradation and in vitro GP parameters of M. thonningii were significantly lower than A. lebbeck. Parameters of in sacco DM degradation and in vitro GP were highly correlated. Millettia thonningii appeared to be of lower feed value than A. lebbeck based on edible forage production, chemical composition, in sacco DM and N degradation and in vitro GP characteristics.     

Responses of Pinus sylvestris and Picea abies Seedlings to Limited Phosphorus Fertilization and Treatment with Elevated Ozone Concentrations

Scots pine ( Pinus sylvestris L.) and Norway spruce [ Picea abies (L.) Karst.] seedlings were exposed to high phosphorus (HP) or low phosphorus (LP) availability for one growing season in the open field, and to combined P availability and elevated ozone (O 3 ) concentrations (0, 55, 110 and 210 ppb for Scots pine and 0, 40, 75 and 150 ppb for Norway spruce, respectively) for 28 days in controlled laboratory chambers. Compared with HP, the LP treatment reduced Scots pine current-year (C) shoot and root dry masses and Norway spruce total dry mass, whereas the highest O 3 concentrations increased the magnesium concentration of Scots pine C needles and P concentrations of the C needles of both tree species. Chlorophyll a, a+b and carotenoid concentrations of Scots pine C needles were significantly higher in the LP treatment compared with HP under the highest O 3 concentration (210 ppb). In the mesophyll tissue of C needles of both tree species, LP treatment increased the size of mitochondria and elevated O 3 -induced granulation of chloroplast stroma and disintegration of cytoplasm. Exposure to elevated O 3 concentrations increased swelling of chloroplast thylakoids and reduced the amount of vacuolar tannin in the LP Scots pine C needles. The results suggest disturbances in needle photosynthetic machinery due to acute exposure to the combination of elevated O 3 and low P availability. However, clear additive effects were found only in needle P concentrations < 1 mg g -1 in short-term O 3 exposure.     

Early growth and seasonal chemical composition of three indigenous multipurpose tree species (MPTS) in Abeokuta,Nigeria

A study was carried out to evaluate the growth parameters and nutritive qualities of Moringa oleifera, Millettia griffoniana and Pterocarpus santalinoides. The main objective of the study was to assess the potential of the MPTS in supplementing the feed of ruminant animals during the dry season when grasses are scarce and their quality generally fall short of animal requirements. Leaf samples were randomly collected from the trees for estimation of the proximate composition, neutral detergent fibre, acid detergent fibre and gas production using the in vitro technique. Samples were collected three times to represent seasonal variations as follows: November: Early Dry; February: Mid Dry and April: Late Dry seasons. Gas production was recorded at 3, 6, 9, 12, 15, 18, 21, 24, 48, 72 and 96 h of incubation. Mortality rate was less than 5%. M. oleifera recorded the best overall growth respectively followed by P. santalinoides and M. griffoniana. P. santalinoides and M. oleifera retained more leaves in the dry season than M. griffoniana. The dry matter (DM) and ether extract (EE) contents of the MPTS were significantly (P < 0.05) affected by seasons and plant species while there were significant (P < 0.05) species effects on the CP and ADF values. The gas production values and the fermentation parameters indicated the presence of potentially degradable nutrients in the MPTS, which underscores the importance of the tree species as sources of nutrient for ruminant animals during the dry season.     

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 dry matter yields and psyllid resistance of thirty-one leucaena selections in Hawaii

Forage yields ofL. leucocephala (Lam). de Wit have been reduced as the result of psyllid damage sinceHeteropsylla cubana Crawford invaded the Hawaiian Islands in 1984. The forage productivity and psyllid resistance of 31Leucaena species and interspecific hybrids were assessed from 5 harvests in Hawaii during 1991 and 1992. The trial consisted of an augmented randomized complete block with 22Leucaena selections in all 4 replicates, 2 selections in 3 replicates and 7 selections in 1 or 2 replicates.Forage (leaves and stems < 6 mm diam.) dry matter (DM) biomass yield over a 13-month period ranged from 1.4 to 34 Mg ha^–1 from total DM ranging from 1.9 to 63.7 Mg ha^–1. Percent forage fractions ranged from 49 to 78% (forage DM/total DM). The 10 selections in this trial of eitherL. pallida Britton & Rose, and its hybrids withL. leucocephala consistently produced both the highest forage and total DM yields averaging 22 and 40 Mg ha^–1, respectively. This represented a three-fold increase in forage production when compared toL. leucocephala K636 (a standard around the world).The excellent performance of theL. pallida lines was attributed to high psyllid resistance and seedling vigor. AllL. pallida selections with the exception of K953 exhibited good psyllid resistance.Leucaena diversifolia Benth. K749,L. pallida K376, andL. esculenta (Moc. & Sesse) Benth. K950 had the highest psyllid resistance (p<0.05). Psyllid damage was negatively correlated to forage DM yield at both harvest 2 and 5 (r=–0.55,p<0.01,n=94). Forage DM was positively correlated to seedling vigor for the first harvest (r=0.83,p<0.001,n=74) and combined harvests (r=0.88,p<0.001,n=74).     

Dry matter production,morphology and nutritive value of <Emphasis Type="Italic">Dactylis glomerata</Emphasis> growing under different light regimes

Plant growth, morphology and nutritive value under shade can differ between temperate grasses. Therefore, the aim of this study was to quantify the dry matter (DM) production, sward morphology, crude protein (CP%), organic matter digestibility (OMD) and macro-nutrient concentrations (P, K, Mg, Ca and S) in a grazed cocksfoot (Dactylis glomerata L.) pasture under 10-year-old Pinus radiata D. Don forest. Four levels of light intensity were compared: full sunlight (100% photosynthetic photon flux density-PPFD), open + wooden slats (∼43% PPFD), trees (∼58% PPFD) and tree + slats (∼24% PPFD). The mean total DM production was 8.2 t DM ha⁻¹ yr⁻¹ in the open and 3.8 t DM ha⁻¹ yr⁻¹ in the trees + slats treatment. The changes in cocksfoot leaf area index (LAI) were related to variations in morphological aspects of the sward such as canopy height and tiller population. CP% increased as PPFD declined with mean values of 18.6% in open and 22.5% in the trees + slats treatment. In contrast, the intensity of fluctuating shade had little effect on OMD with a mean value of 79 ± 3.2%. The mean annual macro-nutrient concentrations in leaves increased as the PPFD level declined mainly between the open and the trees + slats treatments. It therefore appears that heavily shaded dominant temperate pastures in silvopastoral systems limit animal production per hectare through lower DM production rates and per animal through reduced pre-grazing pasture mass of lower bulk density from the etiolated pasture.     

In vivo digestibility and nitrogen balance in sheep diets with foliage of fodder trees in substitution for soybean meal

Apparent digestibility and nitrogen (N) balance were evaluated in sheep fed low-quality Cynodon nlemfuensis grass supplemented with different foliages of forage-potential trees. Four male hair sheep were housed in metabolic cages and fed in a Latin Square design with 30 % inclusion of foliage of Erythrina indica (Ei), Moringa oleifera (Mo), or Trichanthera gigantea (Tg) replacing soybean meal. Adaptation and faeces and urine collection periods were 14 and 7 days, respectively. Sheep received 70 g DM/kg/BW^0.75 of the diet in order to achieve total consumption of feed. Dry matter, organic matter, and neutral detergent fiber digestibilities were similar (P > 0.05) among the control, Mo, and Ei diets, while the Tg diet resulted in the lowest (P < 0.05) value. The Ei diet showed the highest (P < 0.05) total N intake among the three diets with 30 % of leaf meal, which was similar (P > 0.05) to the control diet. N excreted in faeces was highest (P < 0.05) in the Tg diet when compared to the other leaf meal diets, in which the Mo diet presented the lowest (P < 0.05) value, but was similar (P > 0.05) to that found in the control diet. The Mo and Ei diets had similar (P > 0.05) values for the percent of N absorbed by the animals, which was much higher (P < 0.05) than that of the Tg diet. The forage of M. oleifera and Ei can be used in diets at 30 % incorporation to substitute the use of soybean meal in small ruminant production.     

Nitrogen Dynamics in Cropping Systems in Southern Malawi Containing Gliricidia sepium, Pigeonpea and Maize

This study tested the hypothesis that incorporation of green leaf manure (GLM) from leguminous trees into agroforestry systems may provide a substitute for inorganic N fertilisers to enhance crop growth and yield. Temporal and spatial changes in soil nitrogen availability and use were monitored for various cropping systems in southern Malawi. These included Gliricidia sepium (Jacq.) Walp. trees intercropped with maize (Zea mays L.), with and without pigeonpea (Cajanus cajan L.), sole maize, sole pigeonpea, sole gliricidia and a maize + pigeonpea intercrop. Soil mineral N was determined before and during the 1997/1998, 1998/1999 and 1999/2000 cropping seasons. Total soil mineral N content (NO₃⁻ + NH₄⁺) was greatest in the agroforestry systems (p<0.01). Pre-season soil mineral N content in the 0–20 cm horizon was greater in treatments containing trees (≤85 kg N ha⁻¹) than in those without (<60 kg ha⁻¹; p<0.01); however, soil mineral N content declined rapidly during the cropping season. Uptake of N was substantially greater in the agroforestry systems (200–270 kg N ha⁻¹) than in the maize + pigeonpea and sole maize treatments (40–95 kg N ha⁻¹; p<001). Accumulation of N by maize was greater in the agroforestry systems than in sole maize and maize + pigeonpea (p<0.01); grain accounted for 55% of N uptake by maize in the agroforestry systems, compared to 41–47% in sole maize and maize + pigeonpea. The agroforestry systems enhanced soil fertility because mineralisation of the applied GLM increased pre-season soil mineral N content. However, this could not be fully utilised as soil N declined rapidly at a time when maize was too small to act as a major sink for N. Methods for reducing losses of mineral N released from GLM are therefore required to enhance N availability during the later stages of the season when crop requirements are greatest. Soil mineral N levels and maize yields were similar in the gliricidia + maize and gliricidia + maize + pigeonpea treatments, implying that addition of pigeonpea to the tree-based system provided no additional improvement in soil fertility.     

Cutting management of alley cropped leucaena/gliricidia-Guinea grass mixtures for forage production in southwestern Nigeria

A study was conducted at Fasola (7°45 N and 3°5 E) in southwest Nigeria to determine the best tree cutting scheme for forage production and the effects of hedge configurations on tree, grass and total forage productivity of 6–8-year-old leucaena (Leucaena leucocephala Lam. de Wit) and gliricidia (Gliricidia sepium Walp.)-Guinea grass (Panicum maximum Jacq. cv. Ntchisi) mixture. After a uniform cut at the end of January 1990 (mid-dry season), the trees were cut according to the following cutting regimes: one cut after a 12-month regrowth (12M); two cuts after three- and nine-month regrowth (3–9M); two cuts every six months (6-6M); two cuts after nine- and three-month regrowth (9-3M); three cuts, two cuts every three months and the third cut after a six-month regrowth (3-3-6M), and four cuts every three months (3-3-3-3M). Grass was cut every six weeks between April and October followed by a cut in January. The hedge configuration was either one or three hedgerows of mixed stands of leucaena and gliricidia. There were twice as many trees and one-third less grass in the triple than in the single hedgerow hedge configuration.The 3-3-3-3M, 9-3M and 3-3-6M cutting regimes produced the highest total forage (tree foliage + grass) dry matter yields (DM) of 6.54, 5.80 and 5.77 t DM ha^–1 annum^–1, respectively. The magnitude of the difference between the tree forage yields of the triple and single hedgerow plots (16%) did not reflect the theoretical difference in the number of trees (33%) in the two arrangements.