Abubeker Hassen

Effect of Tannin and Species Variation on In vitro Digestibility, Gas, and Methane Production of Tropical Browse Plants

Nineteen tanniferous browse plants were collected from South Africa to investigate their digestibility, gas production (GP) characteristics and methane production. Fresh samples were collected, dried in forced oven, and ground and analyzed for nutrient composition. In vitro GP and in vitro organic matter digestibility (IVOMD) were determined using rumen fluid collected, strained and anaerobically prepared. A semi- automated system was used to measure GP by incubating the sample in a shaking incubator at 39°C. There was significant (p<0.05) variation in chemical composition of studied browses. Crude protein (CP) content of the species ranged from 86.9 to 305.0 g/kg dry matter (DM). The neutral detergent fiber (NDF) ranged from 292.8 to 517.5 g/kg DM while acid detergent fiber (ADF) ranged from 273.3 to 495.1 g/kg DM. The ash, ether extract, non-fibrous carbohydrate, neutral detergent insoluble nitrogen, and acid detergent insoluble nitrogen and CP were negatively correlated with methane production. Methane production was positively correlated with NDF, ADF, cellulose and hemi-cellulose. Tannin decreased GP, IVOMD, total volatile fatty acid and methane production. The observed low methanogenic potential and substantial ammonia generation of some of the browses might be potentially useful as rumen manipulating agents. However, a systematic evaluation is needed to determine optimum levels of supplementation in a mixed diet in order to attain a maximal depressing effect on enteric CH4 production with a minimal detrimental effect on rumen fermentation of poor quality roughage based diet.

Qualitative evaluation of four subtropical grasses as standing hay: diet selection, rumen fermentation and partial digestibility by sheep

The nutritive value of four subtropical grasses (Panicum maximum, Anthephora pubescens, Digitaria eriantha and Chloris gayana) standing hay were compared in terms of qualitative intake and partial digestibility by sheep. The species differed significantly in terms of diet quality selected by sheep grazing the standing hay. The rumen ammonia nitrogen (NH3-N), total volatile fatty acid and propionic acid concentrations of sheep grazing P. maximum and A. pubescens were higher than those sheep grazing D. eriantha and C. gayana standing hay. Organic matter intake (OMI) (g kg−1 W0.75 d−1), nitrogen intake (g d−1), digesta flow, the total N flow, NH3-N flow, non-ammonia nitrogen (NAN) flow and NAN disappearance (g d−1) in the ileum were higher for sheep grazing P. maximum than for those grazing the other standing hays. The organic matter disappearance in the stomach and small intestine of sheep grazing P. maximum and D. eriantha standing hay was higher than for those sheep grazing either A. pubescens or C. gayana standing hay. The NAN flow/N intake were the highest for sheep grazing P. maximum and A. pubescens compared to C. gayana. The NAN digestibility was, however, not significantly different among the four species. The standing hays (except for C. gayana) seemed to have the capacity to meet the N requirement of the sheep for production, but the OMI (g kg−1 W0.75 d−1) was not sufficient to support maintenance requirement of the sheep.

Performance of Arsi-Bale kids supplemented with graded levels of pigeonpea in dry season in Mid Rift valley of Ethiopia

Free grazing/browsing Arsi-Bale kids in dry season were supplemented with different levels of dried pigeon pea ( Cajanus cajun ) leaves to study its effect on weight gain. Kids browsed freely (PP 0), and/or supplemented with 66 g (PP 66 ), 99 g (PP 99 ) and 132 g (PP 132 PP) of sun dried pigeon pea leaves. Supplementation significantly (P<0.05) increased average daily gain of kids but there was no significant (P<0.05) difference between kids supplemented with PP 99 and PP 132 g in terms of total weight gain. There was a significance difference among treatments for net profit and the highest net profit was obtained for PP 99 . Therefore, supplementing kid with PP 99 dried pigeon pea leaves was found to be the most profitable level for rift valley kid under farmer condition in dry season.

Estimation of browse biomass of Ficus thonningii, an indigenous multipurpose fodder tree in northern Ethiopia

Ficus thonningii is a multipurpose browse tree in northern Ethiopia. Despite its importance, techniques for quantifying its browsable biomass have not been developed. To develop best-estimation equations, the dendrometric parameters total height (H), crown height (CH), crown diameter (CD), diameter at stump height (DSH), diameter at breast height (DBH), crown depth (CDp), crown area (CA) and crown volume (CV) were measured from 12 sampled trees comprising three age ranges. Leaves and edible twigs of the sampled trees were clipped, oven dried, weighed and recorded as dry weight (DW). Regression analysis and a multicollinearity test were employed to remove non-significant predictors of DW. Results showed that only CV, CA, CD, CDp and DSH showed a strong correlation with DW. There was high collinearity between CD and CA, CD and CV, and CA and CV. However, CV and DSH had a higher correlation with DW than their counterparts, which suggested their use in the model. Therefore, the best allometric equation was: DW = 0.8470*CV - 0.2202*DSH - 1.5315 (R 2 = 0.99). This equation estimated that F. thonningii produces a very high amount of browsable biomass at all ages compared to common fodder species. The model can be used to plan the browsing rate and understand the ecological role of the species.

Influence of moisture stress on growth, dry matter yield and allocation, water use and water-use efficiency of four Indigofera species

The effects of moisture stress were evaluated in four Indigofera species (I. amorphoides, I. arrecta, I. coerulea and I. vicioides) using a pot experiment under glasshouse conditions. The aim was to examine the influence of moisture-deficit stress on physiological attributes and performance of the four Indigofera species. Based on plant available water (PAW) levels, three moisture levels were applied (no stress or 70–100% PAW, 40–70% PAW and 10–40% PAW) as experimental treatments and imposed on each species in a randomised complete block design with four replications. Moisture stress significantly reduced (p < 0.05) the total leaf area of I. amorphoides at moderate levels and that of I. vicioides at the most severe moisture stress level. The relative growth rate was significantly reduced (p < 0.05) in I. amorphoides but not in I. arrecta, I. coerulea or I. vicioides plants subjected to moisturedeficit stress. The reduction in total dry matter yield was due to the effect of moisture stress in reducing both leaf area and leaf area ratio. Drought stress-tolerance indices were not different (p > 0.05) for I. arrecta or I. coerulea grown under no stress and moisture-deficit stress conditions. The root mass fractions of I. amorphoides and I. arrecta were substantially increased (p < 0.05) due to moisture stress. Water-use efficiency was low in I. amorphoides under water deficit conditions, while that of I. vicioides was higher under severe stress conditions compared to non-stress conditions. Transpiration efficiency was, however, higher at moderate moisture-deficit stress levels than under non-stressed or severely stressed plants. Generally, the species investigated exhibited significant variation in terms of physiological attributes and performance response to moisture-deficit stress. Indigofera amorphoides was relatively sensitive while I. vicioides was able to maintain unabated growth under water stress conditions. This is highly relevant to programmes aimed at identifying suitable species as a source of fodder for livestock exposed to long dry seasons and frequent drought phenomena.

Long-term impacts of grazing intensity on soil carbon sequestration and selected soil properties in the arid Eastern Cape, South Africa.

BACKGROUND Little is known about how basic soil properties respond to contrasting grazing intensities in the Karoo biome, South Africa. The aim of this study was to investigate impacts of long-term (>75 years) grazing at 1.18 heads ha(-1) (heavy; CGH), 0.78 heads ha(-1) (light; CGL), and exclosure on selected soil properties. Soil samples were collected to a depth of 60 cm from the long-term experimental site of Grootfontein Agricultural Development Institute, Eastern Cape. The samples were analyzed for C, N, bulk density and infiltration rate, among others. RESULTS Generally, heavy and light grazing reduced soil N storage by 27.5% and 22.6%, respectively, compared with the exclosure. Animal exclusion improved water infiltration rate and C stocks significantly (P < 0.05), which was 0.128, 0.097, and 0.093 Mg ha(-1) yr(-1) for exclosure, CGL and CGH, respectively. Soil penetration resistance was higher for grazing treatments in the top 3-7 cm soil layer but for exclosure at the top 1 cm soil surface. CONCLUSION Although livestock exclusion has the potential to improve C sequestration, a sufficient resting period for 1-2 years followed by three consecutive grazing years at light stocking rate would be ideal for sustainable livestock production in this arid region of South Africa.

Nutritive Value of Grasses in Semi-arid Rangelands of Ethiopia: Local Experience Based Herbage Preference Evaluation versus Laboratory Analysis

We examined the nutritive value of common grass species in the semi-arid rangelands of Borana in southern Ethiopia using local experience based herbage preference (LEBHP) perception and laboratory techniques. Local pastoralists in the study area were asked to identify common grass species and rank them according to the species’ preferences and palatability to cattle. The pastoralists listed a total of 15 common grass species which were then sampled during the main rain and cold dry seasons and analyzed for crude protein (CP), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and ash content to verify pastoralists’ claim regarding the quality of individual species. The relative feed value (RFV) and dry matter digestibility (DMD) were also calculated using NDF and ADF contents. Spearman’s rank correlation was used to examine possible relationships between laboratory results and pastoralists’ experience on grass quality. Cenchrus ciliaris, Chrysopogon aucheri, Digitaria milanjiana, Eragrostis papposa and Panicum maximum were the top five species based on LEBHP perception. There were indications of inconsistency in terms of LEBHP perception among the different pastoral communities. The chemical composition of all grass species showed significant (p<0.05) variation between sites, seasons and species. The results showed that the CP values for the Borana rangelands were in the range of 8.7% in the main rain season to 5.1% for the cold dry season. The fiber constituents were relatively low in the main rain season compared to the cold dry season. Overall, Digitaria milanjiana had the highest CP (16.5%) content, while the least was recorded with Heteropogon contortus (10.8) and Aristida adoensis (9.8%) during the main rain season. It seems that the spatial variability of landscapes within the wider geographical regions, soil properties and texture, and land-use patterns probably contributed to site differences in species quality. Generally, the RFV of individual grass species was significantly (p<0.05) varied between and within sites. The ranking of species by pastoralists according to their preferences by cattle was highly correlated with the chemical composition of laboratory results of individual grass species with ‘r’ values for CP (0.94), ash (0.95), NDF (−0.98), ADF (−0.93) and ADL (−0.93). We suggest the complimentary use of LEBHP and laboratory techniques in evaluating the nutritive quality of rangeland forage species for sustainable animal production.

Influence of molasses additive and moisture level at ensiling on fermentative characteristics of Panicum maximum

Silages made from directly cut or wilted Panicum maximum treated with or without molasses, were evaluated to determine fermentative characteristics. The grass was harvested at the boot stage of growth and the material of each treatment was ensiled in separate 1kg mini-silos. Compared to day 0 (control), silage pH dropped significantly at day 7 for molasses-treated silage regardless of initial moisture level. In the untreated silage a slightly lower pH was recorded for the unwilted silage. Molasses treatment resulted in a lower silage pH, higher lactic acid and lower acetic acid concentrations starting from day 7 throughout the fermentation period. Compared to prior wilted silages, lower (p < 0.05) pH, higher lactic acid and lower acetic acid concentrations were recorded for directly cut silages throughout the fermentation period. Molasses had no influence on the nitrogen (N) content of silage, but wilting resulted in a higher N content compared to unwilted silage in presence of molasses. Neither the influence of molasses nor the initial moisture level had a significant effect on ammonia nitrogen (NH3-N) concentration on day 7, but an interaction between molasses addition and moisture level was evident on day 21 and 120. The level of ammonia nitrogen increased with fermentation time. The addition of molasses seemed to be beneficial to the fermentation process and resulted in well preserved silage, whereas the effect of initial moisture condition seems to have little significance.

In vitro fermentation, digestibility and methane production of tropical perennial grass species

Abstract. This study characterised 16 tropical perennial grass species in terms of in vitro methane output and related their digestibility and rumen fermentation with methane output. The grass samples were collected, dried in a forced oven, and ground and analysed for nutrient composition. In vitro gas production and organic matter digestibility (IVOMD) were determined using rumen fluid collected, strained and anaerobically prepared. A semi-automated system was used to measure gas production through in vitro incubation at 39°C. Anthephora argentea and Stipagrostis ciliate produced the highest concentration of methane in terms of g kg–1 digestible dry matter (DDM) and g kg–1 digestible organic matter (IVOMD). Cenchrus ciliaris, Setaria verticillata and Panicum coloratum produced the lowest (P < 0.05) methane when expressed in terms of g kg–1 DDM and g kg–1 IVOMD. Ash, ether extract, non-fibrous carbohydrate, neutral and acid detergent insoluble nitrogen, and crude protein were negatively correlated with methane production. Methane production positively correlated with neutral and acid detergent fibre, cellulose and hemicellulose. It is important to focus on screening and selecting perennial grass with higher nitrogen content and low methane production to mitigate methane production under tropical conditions.

In vitro methane and gas production characteristics of Eragrostis trichopophora substrate supplemented with different browse foliage

The research leading to these results has been conducted as part of the AnimalChange Project.