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 Potential of Winter Rye Cultivars in the Gauteng Province of South Africa

Trials were conducted at the Hatfield Experimental Farm to evaluate eight rye cultivars (Secale cereale) in terms of production and development during different seasons. These consisted of a pot experiment, comparing two water regimes, and a field trial, comprising different planting dates, in order to observe phenological development. SSR 729, a South African winter rye, and imported cultivars compared favourably with the traditional cultivars. The winter rye cultivars are good substitutes for the “old” cultivars for the production of green forage in the autumn/winter period

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

Nutritive Value of Guineagrass Cultivars in the Winter as Influenced by Nitrogen Fertilization

The monitoring of yield, structure and nutritive value of four Panicum maximum (Guineagrass) cultivars, utilized as standing hay in the winter, yielded valuable data on the relative importance of nitrogen fertilization and cultivar. While nitrogen had a strong influence on yield and crude protein content it was the differences between cultivars, with respect to soil adaptation and structure, which played a dominant role. It is recommended that future research place particular emphasis on the adaptation of cultivars and genotype differences in structure

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

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

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

Dry Matter Allocation and Nutritive Value of Tropical and Temperate Fodder Trees and Shrubs in the Gauteng Province of South Africa

Fodder tree and shrub species from the genera Albizzia, Atriplex, Cassia, Chamaecytisus, Cytisus, Leucaena, Lupinus, Medicago, Sesbania and Teline were evaluated in terms of their adaptation to local conditions and potential production of protein-rich forage and fuelwood. Atriplex nummularia, Cassia sturtii, Chamaecytisus palmensis, Cytisus maderiensis, Leucaena species, Sesbania sesban and Teline stenopetala offer considerable potential, both in terms of yield of protein-rich forage and/or fuelwood