Nutritional Quality of Available Forages for Small Stock during a Drought in an Arid Pastoral Landscape in South Africa

This study aimed to assess the nutritional quality of the available forage species during a drought in an arid pastoral system in South Africa. Forage biomass was collected during the wet and dry seasons whilst following livestock herds consisting of boer goats, swakara sheep and mixed breed sheep, in both the summer and winter rainfall regions of the pastoral system. Mineral nutrient content in the plant species revealed that the forages utilized by the livestock generally contained adequate concentrations of Mg, Ca, Na, and K to meet the dietary requirements of the small stock in both the winter and summer rainfall areas. Zinc concentrations in more than half of the forages sampled in the summer rainfall area, during both wet and dry seasons, however, were below the required concentrations for small stock. When considering all plant species utilised, the diets were generally adequate in all mineral nutrients. However, none of the forage species contained sufficiently high concentrations of protein to meet the minimum requirements for small stock. These findings therefore show that pastoralists have to deal with chronic low levels of protein during droughts, and their inability to purchase supplementary feed, or to cultivate fodder crops, or temporary emigrate out of the system puts their livelihoods at high risk to climate change

Impaired Perinatal Growth and Longevity: A Life History Perspective

Life history theory proposes that early-life cues induce highly integrated responses in traits associated with energy partitioning, maturation, reproduction, and aging such that the individual phenotype is adaptively more appropriate to the anticipated environment. Thus, maternal and/or neonatally derived nutritional or endocrine cues suggesting a threatening environment may favour early growth and reproduction over investment in tissue reserve and repair capacity. These may directly affect longevity, as well as prioritise insulin resistance and capacity for fat storage, thereby increasing susceptibility to metabolic dysfunction and obesity. These shifts in developmental trajectory are associated with long-term expression changes in specific genes, some of which may be underpinned by epigenetic processes. This normative process of developmental plasticity may prove to be maladaptive in human environments in transition towards low extrinsic mortality and energy-dense nutrition, leading to the development of an inappropriate phenotype with decreased potential for longevity and/or increased susceptibility to metabolic disease

The Diversity of Poisonous Plant Patches in the Arid Rangelands of Namaqualand, South Africa

The Namaqualand region in South Africa is part of the richest arid biodiversity hotspot in the world. Plant distribution and diversity here are impacted by various biophysical and anthropogenic factors. In these landscapes, poisonous plant patches, which pose serious threats to livestock, are widespread but their contribution to the regions biodiversity are not fully understood. This study assessed their plant diversity and compared its matrix. This study was conducted in the semi-arid to arid Steinkopf pastoral area located in Namaqualand where livestock is still herded daily. Twenty-five paired sites were selected based on the dominance of poisonous plants within the genera Tylecodon, Euphorbia and Adromischus. Within these sites, the number and abundance of different plant species were recorded and categorised into different plant functional types. Results showed a significant difference in Shannon Wiener plant diversity where poisonous plant patches displayed a greater diversity compared to sites sampled in the matrix. We interpret these findings as a consequence of herding in the region, where herders do not allow their animals to graze on or near poisonous plant patches. As such, palatable plants, which are absent or low in abundance in the surrounding landscape have a refuge where they can survive and set seed. This study provides evidence that the ethnobotanical knowledge of herders and palette of livestock are also major contributors to the spatial distribution and diversity of plant species in the arid biodiversity hotspot

Assessment of practical applicability and clinical relevance of a commonly used LDL-C polygenic score in patients with severe hypercholesterolemia

Background and aims: Low-density lipoprotein cholesterol (LDL-C) levels vary in patients with familial hypercholesterolemia (FH) and can be explained by a single deleterious genetic variant or by the aggregate effect of multiple, common small-effect variants that can be captured in a polygenic score (PS). We set out to investigate the contribution of a previously published PS to the inter-individual LDL-C variation and coronary artery disease (CAD) risk in patients with a clinical FH phenotype. Methods: First, in a cohort of 628 patients referred for genetic FH testing, we evaluated the distribution of a PS for LDL-C comprising 12 genetic variants. Next, we determined its association with coronary artery disease (CAD) risk using UK Biobank data. Results: The mean PS was higher in 533 FH-variant-negative patients (FH/M-) compared with 95 FH-variant carriers (1.02 vs 0.94, p < 0.001). 39% of all patients had a PS equal to the top 20% from a population-based reference cohort and these patients were less likely to carry an FH variant (OR 0.22, 95% CI 0.10–0.48) compared with patients in the lowest 20%. In UK Biobank data, the PS explained 7.4% of variance in LDL-C levels and was associated with incident CAD. Addition of PS to a prediction model using age and sex and LDL-C did not increase the c-statistic for predicting CAD risk. Conclusions: This 12-variant PS was higher in FH/M- patients and associated with incident CAD in UK Biobank data. However, the PS did not improve predictive accuracy when added to the readily available characteristics age, sex and LDL-C, suggesting limited discriminative value for CAD

Nutritional quality of Calobota sericea fodders. A preliminary assessment

This study aimed to provide preliminary information regarding the nutritional quality of Calobota sericea, a preferred perennial legume forage species from the water-limited rangelands of South Africa. Calobota sericea plant samples were collected from the Namaqualand rangelands in the wet and dry season and analysed for secondary compounds, fibre, protein and mineral nutrient content. The results from the fibre analyses were used to determine the digestibility and energy content of fodders. Preliminary results indicate that C. sericea fodders are of better nutritional quality in the wet season and that protein content, digestibility and energy content is sufficient for maintenance of lambs and dry ewes. The energy content, however, was not sufficient for maintenance of pregnant and lactating ewes. Furthermore, certain mineral nutrients (Na, P and K) were not found in sufficient concentrations in this species, and it was thus suggested that further investigation is needed into whether fertilisation could potentially improve the protein, digestibility and mineral nutrient content of C. sericea fodders