摘要:

The production of a pure lucerne (Medicago sativa) pasture, two lucerne‐grass pastures and two red clover (Trifolium pratense)‐grass pastures was compared at two grazing pressures (3.5 and 4.0 kg DM per small stock unit d‐1) in the Outeniqua area, using Mutton Merino sheep in a put‐and‐take system of grazing. The four legume‐grass pastures consisted of mixtures of the two legumes with combinations of tall fescue (Festuca arundinacea), phalaris (Phalaris aquatica) and brome grass (Bromus unioloides). The average production in terms of dry matter, stocking rate, average daily gain and total live weight gain of the three lucerne‐based pastures was higher and more constant than that of pastures based on red clover. Lucerne was also a more persistent legume component than red clover. Choice of grass species had very little influence on production and the inclusion of grass in both lucerne‐ and clover‐based pastures did not improve production. Pastures with a brome grass component, however, tended to be higher‐producing than the other legume‐grass mixtures. It is concluded that pure lucerne or legume‐grass pastures based on lucerne are the most productive dryland pastures for this area.

ISSN:1022-0119    

DOI:10.1080/10220119.1995.9647855

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Kleingrass (Panicum coloratumL.) forage yield evaluation plots are often established at a density of 6.0 plants m‐2to accommodate mechanical transplanting and harvesting equipment. However, forage crops are usually established from seed at higher plant densities. Experiments were conducted to determine if populations respond dissimilarly to planting density, and if the ability to statistically distinguish among populations is density‐dependent. Two, 2‐y studies compared the yield of five populations of kleingrass at three plant densities (6.1, 10.8 and 24.2 plants m‐2). Although all populations produced more dry matter per plant with decreasing density, population x density interactions were absent. In addition, experiments at all three densities had equivalent power to statistically separate populations. Kleingrass yield trials can be established at a density which will accommodate mechanical transplanting and harvesting equipment with confidence that the relative differences among populations determined from research plots will be similarly observed in swards.

ISSN:1022-0119    

DOI:10.1080/10220119.1995.9647856

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This study was conducted to compare pod and seed characteristics, nutritive value, digestibility and seed survival of intact medic pods after ingestion by sheep. Different diets comprising the intact pods of six cultivars of the medic species that are most widely sown in South Africa, viz.Medicago truncatula(Paraggio, Parabinga, Sephi and Cyprus)M. polymorpha(Santiago) andM. littoralis(Harbinger AR), were randomly allocated to 30 South African Mutton Merino wethers. Representative feed and faeces samples were collected daily and analysed for dry matter (DM), organic matter (OM) and crude protein (CP). Acid detergent fibre (ADF) and neutral detergent fibre (NDF) were also determined and apparent digestibility coefficients were subsequently calculated for DM, OM and CP. Pod and seed characteristics (pod and seed mass, seed to pod ratio, number of seeds per pod, hardseededness and seed recovered after ingestion) were determined.Medicago truncatulacultivars had the highest pod mass (71–91 mg) followed by M.littoralis(27 mg) andM. polymorpha(23 mg). The better seed:pod ratio ofM. polymorpha(34%) andM. littoralis(30%), in comparison to theM. truncatulacultivars (18–28%), were associated with significant (PsO.05) differences in the number of seeds per 100 g of pods. This higher seed content ofM. littoralisandM. polymorphawas also expressed in higher crude protein, digestible protein and digestible organic matter contents in pods.Medicago polymorphahad the highest (95%) andM. littoralisthe lowest level of hardseededness (86%).Medicago polymorpha(23%) was superior to the other cultivars in terms of seed recovered after ingestion by sheep, followed byM. littoralis(9%) andM. truncatulacultivars (4%). This study showed thatM. polymorpha(cv. Santiago) is best suited for utilization by sheep during the summer months when medic pods are the major component of their diet.

ISSN:1022-0119    

DOI:10.1080/10220119.1995.9647857

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The diet selected by Afrino, Dorper and Merino sheep, and Angora goats was studied in the Arid Karoo at Carnarvon. The diets selected by these small stock species and breeds was established through breed by breed comparisons, with a view to raising the stocking rate by combining different breeds. It was established by means of the d‐index, that the diets differed by only 4% to 5% during the growing season. This margin is too small to recommend combining small stock breeds in an effort to ensure greater utilization efficiency through multiple use of the vegetation. During the dormant seasons the diets differed by 14% to 21%. Although this represents a large margin, stocking rate adjustments are made on the basis of the growing season's results.

ISSN:1022-0119    

DOI:10.1080/10220119.1995.9647858

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The diet selection of Angora and Boer goats, and Dorper and Merino sheep was studied in the Noorsveld to ascertain differences in their food preferences. This information will facilitate the identification of possible goat and sheep combinations to improve the utilization of this veld type. Dorper and Merino sheep and Angora goats selected very similar diets while the diet selected by Boer goats differed by approximately 30% from those of the other animals. We therefore hypothesise that a combination of Boer goats and either Merino or Dorper sheep in the appropriate ratio could lead to the improved utilization of Noorsveld. This needs further investigation as intake of preferred plants may additionally play an important role in establishing better stock ratios.

ISSN:1022-0119    

DOI:10.1080/10220119.1995.9647859

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The distribution of sweet‐ and sourveld in relation to climate, parent material and soil nutrients has been examined in South Africa's grassland biome. Sourveld occurs in areas with high water supply and where parent material gives rise to soils with a low base status. Sweetveld occurs in areas with low water supply and where parent material gives rise to soils with a high base status. The distribution of sweet‐ and sourveld does not seem to be determined by base status itself, but by the concentration of available phosphorus and the size of the readily mineralizable nitrogen pool in the soil. The difference between the temperatures in the growth (wet) and no‐growth (dry) seasons also appears important, but the relation is not clear. We propose that aspects of the environment which promote carbon assimilation (water supply and temperature) in relation to nutrient supply (soil fertility, water supply and temperature) determine the forage quality of grassland vegetation. Sourveld occurs where carbon assimilation is high relative to nutrient supply, and sweetveld where nutrient supply is high relative to carbon assimilation. Mixed veld is intermediate between these two.

ISSN:1022-0119    

DOI:10.1080/10220119.1995.9647860

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The15N natural abundance and15N dilution methods were used to determine the viability of using eitherLolium multiflorum(annual ryegrass) or uninoculatedTrifolium subterraneum(subterranean clover), as non‐fixing reference crops in N2‐fixation studies. The δ13N values for the15N natural abundance method and atom%15N values for the15N dilution method for plant and soil samples are presented. The ryegrass pastures showed the least variation in δ15N and atom%I5N values between experimental plots. This crop appeared to be a more appropriate choice in such studies, but further investigation is needed to confirm this observation. The use of uninoculated subterranean clover as a reference crop seemed problematic, since inoculation with effective rhizobia could not be prevented. Relatively high variation in δ15N values for inoculated subterranean clover was obtained compared to the atom%15N values. This result indicated that the use of the15N natural abundance method should be evaluated for other pasture legume species.

ISSN:1022-0119    

DOI:10.1080/10220119.1995.9647861

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:1022-0119    

DOI:10.1080/10220119.1995.9647854

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor