Feeding Behavior of Sheep in Relation to Kinetics of Sagebrush Monoterpenes: Implications for Landscape Biodiversity

The sagebrush steppe is one of the most extensive vegetation types in the western US and an important habitat for wild and domestic herbivores. When sagebrush dominates, however, forage and habitat quality decline. Although sagebrush is nutritious, its forage value is reduced by terpenes. A better understanding of how terpenes limit intake is vital for increasing consumption of sagebrush and for enhancing and maintaining biodiversity in the sagebrush-steppe. To better understand how terpenes in sagebrush limit intake, we studied feeding behavior of sheep in the field, influence of sagebrush monoterpenes on regulation of intake in pens, and the feeding behavior of lambs in relation to the kinetics of camphor, 1,8-cineole, and p-cymene dosed intravenously and intraruminally. In field studies, supplemented ewes utilized more sagebrush than unsupplemented ewes. In pen studies, food intake and dietary concentrations of monoterpenes were inversely related. Lambs regulated feeding bout frequencies to minimize the toxic effects of monoterpenes. We proposed four complementary hypotheses to account for physiological mechanisms by which monoterpenes influence feeding behavior: 1) monoterpenes disturb acid-base balance, 2) monoterpenes cause satiation, 3) monoterpenes induce elimination pathways, and 4) rumen microbes adapt to monoterpenes. The first two addressed how monoterpenes limit intake and the last two addressed adaptation to monoterpenes. There was no induction of elimination pathways or disturbance of acid-base balance. Camphor, 1,8-cineole, and p-cymene dosed individually and in a cocktail affected feeding behavior and limited food intake by lambs. Feeding time did not change with repeated intravenous dosing with camphor, increased slightly with intravenous dosing with p-cymene and the terpene cocktail, but declined with intravenous dosing with 1,8-cineole. Lambs increased feeding time and food intake with repeated rumen dosing with camphor, 1,8-cineole, and the cocktail. Feeding time and food intake did not change with rumen dosing with p-cymene. Exposure to a terpene-containing diet led to rumen microbial adaptation, while kinetic rates remained unchanged. Satiation, elimination rates, and rumen microbe adaptation influence feeding time and food intake of lambs. Timing of grazing, supplements, stock density, and detoxification of sagebrush monoterpenes influence feeding behavior of sheep, with significant implications for biodiversity of sagebrush-grassland ecosystems

Career Management for Early Career Scientists in Developing Countries--A South African Experience

This paper discusses career development and options for growth for young scientists in developing countries. We also identify and address some of the common challenges early career scientists face, and apply key principles learned from years of research and experience in the South African context as a basis for our discussion. Early career scientists are more likely to succeed in their career if they understand from the start what they need to do in order to grow to the next level and ultimately to the pinnacle of their careers. Strategically, planning one’s individual career development is critical to success in the science environment as is the case in any other discipline or domain. The development of early career scientists through their career ladder is determined by a number of factors, many of which are within the control of early career scientists. These factors include qualifications, publication track record, attracting research funding, contribution to student training and staff development, leadership in science, and research impact. The contribution of this basket of measures to development of a career in science is critical for development to certain milestones in one’s career. One of the most critical transitions many research scientists have to make is the move from specialist to manager. Expedient promotion of early career scientists to senior management roles without an adequate track record, experience or proper training can be frustrating for both the manager and those under his/her management responsibility. Regardless of the career path one chooses, a solid foundation in research with a good track record of research outputs, funding and the impact of one’s research are crucial to one’s development along either the researcher career ladder or research management career path

The Effects of Seed Ingestion by Livestock, Dung Fertilization, Trampling, Grass Competition and Fire on Seedling Establishment of Two Woody Plant Species

The increasing rate of woody plant encroachment in grasslands or savannas remains a challenge to livestock farmers. The causes and control measures of woody plant encroachment are of common interest, especially where it negatively affects the objectives of an agricultural enterprise. The objectives of this study were to determine the effects of gut passage (goats, cattle), dung (nutrients), fire, grass competition and trampling on establishment of A. nilotica (Fabaceae) and D. cinerea (Fabaceae sub family Mimosoideae) seedlings. Germination trials were subjected to: 1) seed passage through the gut of cattle and goats and unpassed/ untreated seeds (i.e. not ingested), 2) dung and control (no dung), 3) grass and control (mowed grass), 4) fire and control (no fire), 5) trampling and control (no trampling)

Response of land surface phenology to variation in tree cover during green-up and senescence periods in the semi-arid savannas in Southern Africa

Understanding the spatio-temporal dynamics of land surface phenology is important to understanding changes in landscape ecological processes of semi-arid savannas in Southern Africa. The aim of the study was to determine the influence of variation in tree cover percentage on land surface phenological response in the semi-arid savanna of Southern Africa. Various land surface phenological metrics for the green-up and senescing periods of the vegetation were retrieved from leaf index area (LAI) seasonal time series (2001 to 2015) maps for a study region in South Africa. Tree cover (%) data for 100 randomly selected polygons grouped into three tree cover classes, low (40%, n = 34), were used to determine the influence of varying tree cover (%) on the phenological metrics by means of the t-test. The differences in the means between tree cover classes were statistically significant (t-test p < 0.05) for the senescence period metrics but not for the green-up period metrics. The categorical data results were supported by regression results involving tree cover and the various phenological metrics, where tree cover (%) explained 40% of the variance in day of the year at end of growing season compared to 3% for the start of the growing season. An analysis of the impact of rainfall on the land surface phenological metrics showed that rainfall influences the green-up period metrics but not the senescence period metrics. Quantifying the contribution of tree cover to the day of the year at end of growing season could be important in the assessment of the spatial variability of a savanna ecological process such as the risk of fire spread with time.The Council for Industrial and Scientific Research (CSIR) Parliamentary Grant, Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL) and ECOPOTENTIAL project which received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 641762.http://www.mdpi.com/journal/remotesensingam2017Plant Production and Soil Scienc

‘Preventing the next pandemic’ – A 2020 UNEP Frontiers Series Report on zoonotic diseases with reflections for South Africa

Zoonoses account for about 25% of the infectious disease burden in low-income countries. Poverty might increase the risk for zoonotic disease where the active human–livestock and human–wildlife interfaces can increase the likelihood of disease transmission. A combined disease burden exists for people in areas such as tropical and subtropical Africa, where there is likelihood of co-infection with zoonotic diseases and other pathogenic or infectious diseases, such as malaria, tuberculosis and HIV.1 Many endemic zoonoses remain widely neglected in such settings, undetected and underreported, because their impacts are borne largely by impoverished and marginalised communities. Due to these unique contexts, the prevention and management of emerging and endemic zoonotic diseases in many African countries is a complex undertaking needing evidence-based guidance. In early 2020, the United Nations Environment Programme (UNEP) and the International Livestock Research Institute (ILRI) took on the urgent task to provide an up-to-date, rapid scientific assessment on zoonotic diseases as part of the UNEP’s Frontiers Report Series. The goal of the report is to provide relevant information for policymakers on how to ‘prevent the next pandemic’ by interrogating what is known about zoonotic diseases and how best one can break the chain of transmission. As the world presently faces the SARS-CoV-2 pandemic, this timely report helps decisionmakers with evidence-based actions, not only to flatten the curve of COVID-19 incidence, but to answer questions about zoonoses in general and plan for the future. In this Commentary, we give a brief overview of UNEP’s latest report and then relate some of the key messages and recommendations for policymakers to a South African context.http://www.sajs.co.zahj2020Geography, Geoinformatics and MeteorologyMammal Research InstituteZoology and Entomolog

The treatment combination effects of animal species (goats, cattle), unpassed/untreated seeds (i.e. not ingested), seed species (<i>A</i>. <i>nilotica</i>, <i>D</i>. <i>cinerea</i>), grass (G) (and mowed grass (Gc)), fire (F) (and no fire (Fc)) on seedling emergence during the dry season.

<p>Bars represent standard errors (S.E). Same letters on the bars mean that P > 0.05. A LSD <i>post hoc</i> test was used.</p

The treatment combination effects of animal species (goats, cattle), unpassed/untreated seeds (i.e. not ingested), grass (G) (and mowed grass (Gc)), fire (F) (and no fire (Fc)) on seedling recruitment during the dry season.

<p>Bars represent standard errors (S.E.). Same letters on the bars mean that P > 0.05. A LSD <i>post hoc</i> test was used.</p

Leaf chemistry of woody plants in relation to season, canopy retention and goat browsing in a semiarid subtropical savanna

It is assumed that the phytochemistry of browse species protects their biomass and nutrients against herbivory. In this study we were primarily interested in (i) seasonal and phenology-related variations in leaf chemistry, and (ii) chemistry-related variations in the feeding behaviour of domestic goats. Such knowledge would guide management-orientated modelling of browse-browser interactions in seasonal, subtropical zones where goats are abundant. The browse species studied were typical of semiarid savannas in southern Africa: Grewia occidentalis L. (Tiliaceae), Scutia myrtina (Burm. f) Kurz (Rhamnaceae), Diospyros lycioides Desf. ssp. lycioides (Ebenaceae), Rhus longispina Eckl. and Zeyh. (Anacardiaceae), Ehretia rigida (Thunb.) Druce (Boraginaceae) and Acacia karroo Hayne (Mimosoideae). Nitrogen (N), phosphorus (P), condensed tannins (CT), protein-precipitating tannins (PPT), total phenols (TP), cellulose and lignin concentrations were estimated for each species during the late dormant and early growing seasons. N, P, CT and TP were elevated during the growth season, while cellulose, lignin and PPT decreased. Unlike cytoplasm contents, which varied seasonally, cell wall and vacuole contents varied both seasonally and among species. Except that seasonal variation in N of deciduous species was greater than that of evergreen species, leaf phenology was not related to variations in forage quality. Short-term intake rates were not related to primary metabolite concentrations, but were positively related to secondary metabolites. Elevated intake rates of putative defences were concluded to be side-effects of attempts by goats to increase nutrient intake rate, indicating tolerance of chemical defences. Without support for the hypothesis that chemical defences are correlated to canopy retention, we propose an alternative hypothesis, that defences are distributed among woody plants in semiarid, subtropical savannas according to shoot morphology because it affects the vulnerability of plant parts to browsers

Chromatographic Analysis of Sagebrush Monoterpenes in Blood Plasma

An analytical method is required for the analysis of monoterpenes in animal plasma to support a pharmacokinetic study. Monoterpenes common to sagebrush are extracted from sheep plasma by employing solid-phase extraction (SPE), followed by analysis of the extracts by gas chromatography with flame ionization detection. The analytes are quantitated versus an external standard and by comparison with a surrogate standard added to the sample prior to extraction. In addition to comparing the two quantitative methods, the storage stability of the analytes in plasma and SPE columns is evaluated. Both methods employed for quantitation yield precision suitable for pharmacokinetic studies. However, determination of monoterpenes residues versus external standards produces improved accuracy as compared with use of the surrogate standard. Some analyte loss is observed from plasma samples stored for five weeks at –12°C. However, storage of extracts on the SPE columns affords excellent stability