Intake and Partial Digestibility of Panicum Maximum (CV. Gatton) at Three Stages of Maturity During Summer

The objective of this study was to determine the influence of stage of maturity on the intake and digestibility of P. maximum (cv. Gatton) during the active growing season. Low DM content at the young and medium growth stages (24.9 and 25.2%) did not hamper DOMI (48.8 and 44.1 g/kg W0.75/d) respectively. The N concentration of the three stages were well within the limit required for optimal rumen microbial production (1.8 - 2.0%). The high NDF value of the adult stage (59.5%) resulted in a significantly lower IVDOM value (62.3%) but the IVDOM values of all stages were on the higher side (average 66.4%) of the spectrum for C4-grasses. Significantly higher NH3-N and VFA levels in the rumen fluid were obtained for the young and medium growth stages and the same trend was observed for DOMI and N-intake. The higher DOMI resulted in a higher digesta flow rate in the abomasum and ileum. The lower DOMI of the adult stage was most probably due to the taller growing sward. Differences in the proportionally OM disappearance in the stomach didn’t differ (average 0.63) but was higher in the small intestine for the younger growth stages. The very high proportional disappearance of non- NH3-N in the small intestine, indicates that ± 30% OM which disappeared in the small intestine, must have consisted primarily of protein matter. The fact that about 70% of N intake was apparently digested in the small intestine, may be the function of a lower soluble N content

The Effect of Long-Term Grazing Treatments on the Establishment of Woody Plants in a Southern African Savanna

Eight paddocks which were debushed to an open savanna during 1935/36 and subsequently grazed annually during different seasons by steers were surveyed after a period of 54 years. Though woody plants have increased in all the paddocks, regardless of the grazing treatment, the rate of woody plant establishment was notably higher in those paddocks that received a more intense annual grazing treatment. This effect was most noticeable in those paddocks of which the mean Animal Unit-grazing days ha-1 exceeded 100 days annually. These results confirm the existence of a positive linear relationship between the severity of the grazing treatment and the rate at which woody plants have increased

Seed Production and Quality of Buffelgrass (\u3ci\u3eCenchrus ciliaris\u3c/i\u3e) Selections

As seed production and quality are critical considerations in the commercialization of new cultivars, an evaluation programme of promising Cenchrus ciliaris (Buffelgrass) accessions placed particular emphasis on these parameters. Accessions identified for registration proved to be superior in both respects, although storage of seed or cleaning of fresh seed reduced the differences in germination between accessions. The refinement of seed cleaning processes should receive greater emphasis by commercial concerns

Intake and Quality of Panicum Maximum (CV. Gatton) Receiving Different Levels of Nitrogen During Autumn

The objective of this study was to investigate the influence of N fertilization on the quality of Panicum maximum cv. Gatton (Panicum) and the subsequent intake thereof. Hand cut samples increased in N (1.8 - 2.7%) and NO3-N content (0.75 - 1.54%) and decreased in WSC (14.6 - 13.9 g/kg) content, but with no changes in IVDOM as N fertilization levels raised from 0 to 150 kg N/ha respectively. No changes occurred in the NDF and ADL values. The animal selected N, and IVDOM values were higher and NDF value lower than the hand cut samples, which was expected due to selective grazing. The lower WSC content together with a higher N as well as NO3-N level in the highly fertilized treatments, could have been responsible for a lower flow of microbial protein to the duodenum, which could have been partly responsible for the lower DOMI at such levels. Fertilization levels of 125 kg and higher can cause negative animal production results of P. maximum, (cv. Gatton) during autumn, due to a drop in intake and too high levels of NO3-N, which may cause ill health

Competition for Light in a \u3ci\u3eLeucaena leucocephala / Chloris gayana\u3c/i\u3e Silvopastoral System

The spatial variation in the vigour of Leucaena (Leucaena leucocephala cv. Cunningham) trees growing together with Rhodesgrass (Chloris gayana cv. Katambora) in an alley cropping system made it possible to assess the competitive effect for light. The height and especially lateral development of trees had a strong influence on light interception by the canopy, with radiation in the intercrop area being 49% lower where the trees were more vigorous. There was a corresponding (43%) decrease in grass production. These findings indicate that future studies should also include aspects such as espacement of trees, pruning of trees in the growing season, choice of shade tolerant grasses and the competitive effect for water

The Effect of Alternative Soil Amendments on the Botanical Composition, Basal Cover, Dry Matter Production and Chemical Properties of Re-Vegetated Mine Land

Coal mining impacts large grassland areas of the Mpumalanga Province of South Africa. To mitigate such impacts, it is imperative to restore the once productive soils to the best possible condition. The revegetation of mine land presents a particular challenge. Soils being rehabilitated are often acidic and nutrientdeficient, which are major limiting factors in re-vegetation programmes. Conventional methods of liming and inorganic fertilisation have been used to improve the productivity of impacted soils. In the past few years the use of a coal combustion by-product, class F fly ash, and an organic material, such as sewage sludge, have demonstrated the feasibility of using such materials to amend acidic and infertile substrates (Truter, 2002; Norton et al., 1998). The objective of this research was to determine if alternative amendments can create a more sustainable system where botanical composition, basal cover, dry matter production and soil chemical properties can be improved

The Influence of Plant Density and Level of Nitrogen Fertilization on the Production of Eragrostis Curvula

The objective of this study was to determine whether plant density would have an influence on dry matter (CM) yield and to determine it’s interaction (if any) with levels of N fertilization. Plants on a broadcast establishment of lovegrass (Eragrostis curvula) were mechanically thinned, to leave 30 cm rows with spacing of 0.5 and 1 m. N fertilizer was applied in spring at levels equivalent to 0, 50, 100 and 150 kg N ha-1. The trial was conducted over three growing seasons. In the second and third years the DM yields with 100 and 150 kg N ha-1 on the broadcast establishment were significantly higher that with other treatment combinations

Effect of Pre-Planting Seed Treatment Options on Dormancy Breaking and Germination of \u3cem\u3eZiziphus Mucronata\u3c/em\u3e

Ziziphus mucronata (Buffalo thorn) is a multipurpose tree, widely adapted to a range of ecological conditions and tolerant of extreme climatic conditions, including frost and drought (Venter & Venter, 1996). It is a valuable fodder tree for livestock and game animals, especially in the drier parts of Africa (Rothauge et al. 2003). Similar to many other leguminous species, establishment is constrained by low and erratic germination of the seed, which has been attributed mainly to the physical barrier of the stony endocarp and dormancy associated with seed coat impermeability . This experiment aimed to compare the suitability of various seed treatment options as practical methods to break seed dormancy and enhance germination

Effect of Pre-Planting Seed Treatment Options on Dormancy Breaking and Germination of \u3ci\u3eZiziphus Mucronata\u3c/i\u3e

Ziziphus mucronata (Buffalo thorn) is a multipurpose tree, widely adapted to a range of ecological conditions and tolerant of extreme climatic conditions, including frost and drought (Venter & Venter, 1996). It is a valuable fodder tree for livestock and game animals, especially in the drier parts of Africa (Rothauge et al. 2003). Similar to many other leguminous species, establishment is constrained by low and erratic germination of the seed, which has been attributed mainly to the physical barrier of the stony endocarp and dormancy associated with seed coat impermeability. This experiment aimed to compare the suitability of various seed treatment options as practical methods to break seed dormancy and enhance germination

The Influence of Intensity of Tree Thinning on the Redistribution of Soil Water in Southern African Mopani Veld

The investigation was conducted on a densely wooded area in the Mopani veld of South Africa. Six plots were subjected to different intensities of tree thinning, ranging from a totally cleared plot (0 %) to plots thinned to the equivalent of 10%, 20%, 35%, 50% and 75% of the leaf biomass of a control plot (100%). Soil water measurements were taken at six different depths to a depth of 825 mm. The infiltration of rain water and redistribution within the soil profile exhibited marked differences between experimental plots. The soil water was predominantly held at a very shallow depth (\u3c450 mm). Increased infiltration in plots with a low tree density occurred and was associated with the establishment of grasses. No stratification of soil water between the topsoil and subsoil could be established which means that the C. mopane trees and grasses are in direct competition for soil water in the upper soil layers