Worldwide, the invasiveness of Opuntia spp. and its impact on various ecosystem services has been recognised especially in semi-arid areas where rainfall is erratic. The semi-arid environments are the habitats of plants which have adapted to be able to grow in severe hot and dry regions. Opuntia spp. normally thrives in conditions of high temperatures, low rainfall, saline soils and it can also adapt and survive in severely degraded soils which have a limited nutrients supply. Its positive impact includes its recognised value as livestock fodder. Opuntia’s adaptability to harsh conditions, high dry matter yield, palatability and significant levels of energy, as well as its availability at a low cost during the dry season, decreases the use of expensive supplements and conventional diets in many areas. There is a need to understand the importance of this invasive Opuntia species when incorporated in animal diets. As a part of its control measures, the use of livestock in controlling the spread of Opuntia may assist in reducing its abundance and invasiveness while at the same time providing a consistent supply of forage during the dry season. Information on its nutritive value, incorporating the species in animal diets and the means to control it must be well understood to recognise the species’ contribution to an ecosystem.

Among the possible impacts of plant invaders on South African biodiversity, water supplies, and rangeland production, Lantana camara is ranked the highest in terms of its environmental impact. Globally, L. camara is regarded as one of the most ecologically and economically destructive invasive alien plants. The spread of L. camara affects the environment and threatens livestock productivity due to its toxicity to animals (especial cattle and sheep) in most semi-arid areas of South Africa. Lantana camara is known to have high concentrations of nutrients that are beneficial to livestock, but most previous research has concentrated on its toxicity. To enrich our knowledge on its nutritive value, further research has to evaluate its dietary impact on the growth and health of different ruminant livestock species, particularly goats. This review evaluates L. camara as a potential browse species for goats in southern Africa, and its adverse effects on goats and other ruminant livestock are also presented. The review describes L. camara and its distribution globally, its poisonous effect to livestock, and potential use as an alternative forage to browsing animals such as goats, which have proved resistant to its harmful traits. The high crude protein content, low fibre and adequate macro-minerals for small ruminants makes L. camara a good ruminant protein supplement in semi-arid areas. In addition to other biological control strategies, the prospects of using goats as a biological management tool is discussed. The research will contribute to the understanding of the control measures of L. camara while improving the productivity of small stock, especially goats. This means that a balanced understanding of its nutritional value as a source of protein and its negative impact on the environment should be considered in developing mitigation strategies to arrest its spread. We, therefore, recommend the use of goats in the control of L. camara; however, further studies are needed to limit its toxic effects, and thus improve its value.

Globally, there have been differing views on whether the proliferation of invasive species will be of benefit as a livestock feed source or it will have detrimental effects on the ecosystem. The infestation of invasive plants such as Prosopis species does not only affect the groundwater levels but also threatens the grazing capacity and species richness of most of the semi-arid areas around South Africa. Though Prosopis is invasive, it is however of good nutritive value and can serve as an alternative source of protein and minerals for livestock during the dry season. Bush encroachment by browsable invasive species can be controlled through biological methods by using organisms such as livestock. The utilisation of Prosopis through browse benefits livestock production and at the same time reduces its spread, thereby preventing possible environmental harm that may arise. Although several studies have been carried out globally on the assessment of the Prosopis species’ nutritive value and also on the threat of this invasive species to the environment, there is a need to update the state of knowledge on this species, particularly in the context of the semi-arid areas of South Africa where the dry season is characterised by less herbage of poor quality. It is therefore critical to understand whether Prosopis is a beneficial invader, or a detriment that needs to be eradicated. This review will contribute knowledge towards finding practical solutions to controlling Prosopis species and whether utilising Prosopis as a feed source will limit its spread and result in a vegetation structure where Prosopis becomes part of the ecosystem with limited detrimental impact. This means that the several components of the species such as nutritive value and the negative impact associated with this plant species along with the means to control its spreading must be well understood to recognise the plant species’ vital contribution to the ecosystem.

Cropland abandonment has been happening in different parts of the world and is being driven by socio-economic, ecological, edaphic, and environmental factors. Most of the research focusing on drivers of cropland abandonment, succession trajectories, and responses to active restoration initiatives has been conducted in the republic of Nepal and regions such as Europe and America. In South Africa, the impact of cropland abandonment on household livelihoods, changes in vegetation and soil properties, and soil seed bank statuses have been conducted mainly in the Eastern Cape Province. The drivers of cropland abandonment in South Africa are like those observed in other countries, except for a few, which are country-specific such as poor support of communal farmers compared to their counterparts in the highly mechanised commercial farming sector. There is also a shift from low input cropping in the distant fields to high input cultivation in homestead gardens. Research results elsewhere suggest a woody growth suppressive effect of grazing, particularly average grazing intensities, being crucial in suppressing woody proliferation while high grazing intensities are detrimental to herbaceous species’ richness and promote woody species’ encroachment. A combination of fire and grazing alters the natural succession trajectory by promoting fire-tolerant species and arresting woody species. Similar to other countries, cropland abandonment is associated with colonisation by alien invasive species which are favoured by cropping legacies, such as altered soil levels of pH, Nitrogen, and phosphorus. Furthermore, limited moisture in semi-arid areas promotes the encroachment of indigenous woody species. Secondary succession in abandoned croplands can be manipulated for the benefit of livestock production in communal areas by introducing management strategies that will discourage encroachment by both invasive and indigenous woody species which lowers the grazing capacity. Furthermore, active restorative practices, such as reseeding with indigenous mid succession perennial grasses and legumes, will improve forage quality in abandoned croplands. Our understanding of succession trajectories under various unique disturbance regimes experienced in South Africa, such as communal grazing of abandoned croplands, compared to situations in other parts of the world is limited. Furthermore, the influence of other factors such as fire, soil fertility, and moisture needs to be understood.

In semi-arid regions, browse plant species are used as feed and for medicinal purposes for both animals and humans. The limitation of the utilization of these species to medicinal purposes or as feed for livestock is a lack of knowledge on the concentration level of phytochemicals and other bioactive compounds found in these plants. The study sought to assay the qualitative and quantitative bioactive constituents of some browse species found in the savannah biome of South Africa, viz. Adansonia digitate, Androstachys johnsonii, Balanites maughamii, Berchemia discolor, Berchemia zeyheri, Bridelia mollis hutch, Carissa edulis, Catha edulis, Colophospermum mopane, Combretum Imberbe, Combretum molle, Combretum collinum, Dalbergia melanoxylon, Dichrostachys cinerea, Diospros lycioides, Diospyros mespiliformis, Euclea divinorum, Flueggea virosa, Grewia flava, Grewia flavescens, Grewia monticola, Grewia occidentalis, Melia azedarach, Peltophorum africanum, Prosopis velutina, Pseudolachnostylis maprouneifolia, Pterocarpus rotundifolius, Schinus molle, Schotia brachypetala, Sclerocarya birrea, Searsia lancea, Searsia leptodictya, Searsia pyroides, Senegalia caffra, Senegalia galpinii, Senegalia mellifera, Senegalia nigrescens, Senegalia polyacantha, Strychnos madagascariensis, Terminalia sericea, Trichilia emetic, Vachellia erioloba, Vachellia hebeclada, Vachellia karroo, Vachellia nilotica, Vachellia nilotica subsp. Kraussiana, Vachellia rechmanniana, Vachellia robusta, Vachellia tortilis, Vachellia tortilis subsp. raddiana, Vangueria infausta, and Ziziphus mucronata. These browse species’ leaf samples were harvested from two provinces (Limpopo and North-West) of South Africa. The Limpopo province soil type was Glenrosa, Mispah, and Lithosols (GM-L), and the soil types in the North-West Province were Aeolian Kalahari Sand, Clovelly, and Hutton (AKS-CH). The harvested browse samples were air dried at room temperature for about seven days and ground for analysis. The methanol and distilled water extracts of the browse species leaves showed the presence of common phytoconstituents, including saponins, flavonoids, tannins, phenols, cardio glycosides, terpenoids, and phlobatannins, as major active compounds in browse species leaves. In the quantitative analysis, phytochemical compounds, such as soluble phenols, insoluble tannins, and condensed tannins, were quantified for common species found in both sites. Two-way ANOVA and multivariate analysis were used to test soil type and species effect on soluble phenols, insoluble tannins, and condensed tannins of woody species. Dichrostachys cinerea (0.1011% DM) in GM-L soil type and Z. mucronata (0.1009% DM) in AKS-CH soil type showed the highest (p < 0.05) concentration of soluble phenols. In AKS-CH soil type, D. cinerea (0.0453% DM) had the highest insoluble tannins concentration, while V. hebeclada had the lowest (0.0064% DM) insoluble tannins content. Vacchelia hebeclada had lower (p < 0.05) condensed tannins concentration levels than all other browse plants in both soil types. Under multivariate analysis tests, there was a significant effect (p < 0.001) of soil type, species, and soil type x species interaction on soluble phenols, insoluble tannins, and condensed tannins of woody species. In this study, most of the woody species found in GM-L soil type showed a lower amount of tannins than those harvested in AKS-CH soil type. There is a need to identify the amount of unquantified phytochemicals contained in these browse species and valorize the high-bioactive-compound browse species to enhance and maximize browsing of these browse species for animal production.

The objective of this study was to investigate the nutritive value, in vitro dry matter degradability (IVDMD), and ensiling characteristics of legume foliage–maize straw silages. For silage, the proportion of legume to maize was 20%:80% (maize–lablab (ML), maize–indigenous cowpea (MI), maize–Betswit (MB), and maize–Dr Saunders (MD)). Maize alone (M) was used as a control, making up five treatments. Silages were opened after 45 days, and samples were taken for chemical composition, IVDMD, and fermentation characteristics analysis. Other samples were put through a seven-day aerobic stability test. All data were subjected to a one-way analysis of variance, in a completely randomized design (CRD). For the nutritive value of the silage, the ML had the highest (p < 0.05) crude protein (CP) content, when compared with other silages. Maize–Betswit had the lowest (p < 0.05) neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL) content, when compared with other silages. The lowest (p < 0.05) ether-extract (EE) and hemicellulose content was recorded for MI silage. The lowest (p < 0.05) pH was recorded for maize silage. All silages had similar (p > 0.05) amounts of lactic acid (LA), water-soluble carbohydrates (WSC), yeast, and mould counts. The MI had the lowest (p < 0.05) carbon dioxide (CO₂) concentration, when compared with other silages. The highest (p < 0.05) IVDMD was recorded for ML silage, from 24 h up to 72 h. The addition of legumes in maize straw resulted in improved silage quality and fermentation characteristics.