Pretoria, South Africa
Pretoria, South Africa

Time filter

Source Type

Barnard A.,Small Grain Institute | Calitz F.J.,Biometry Unit
South African Journal of Plant and Soil | Year: 2011

High quality seed is essential for establishing productive stands of wheat. Seed should have, amongst others, a high germination percentage, be free of seed borne diseases and should not contain any weed seed. Protein content (PC), hectolitre mass (HLM) and falling nudmber (FN) are three important quality characteristics determining the grading of wheat at delivery point. Seed with high and low values of these three quality requirements were planted over a two year period under dryland and irrigation conditions to determine the effect of these quality parameters on the yield of the following crop. Seed with various levels of preharvest sprouting damage were also planted to determine the effect of sprouting on the field performance of the crop. Results from this study showed that germination was not affected by grading factors, but the emergence of seed with low HLM was significantly reduced compared to high HLM seed. Low PC had a significant effect on the crop, especially under dryland conditions, while FN did not have an effect. Severely sprouted seed had a significant negative effect on the emergence and yield, especially when seeds were carried over to the next planting season. However, a low intensity of sprouting did not affect the yield negatively. End results indicated that using low quality seed for planting can have a negative effect on crop yield. It is concluded that producers should use certified seed that is true to variety, is clean and has a high germination percentage for crop production.


Brits G.J.,Institute for Fruit Research | Brown N.A.C.,National Botanical Institute | Calitz F.J.,Biometry Unit
South African Journal of Botany | Year: 2014

The effect of germination incubation regimes, which were chosen on the basis of temperature patterns found within the fynbos (Mediterranean fire-prone shrubland-type) habitat in the Cape Floristic Region during the autumn germinative period, was tested on seeds of 6 Leucospermum species over 5 taxonomic sections (L. cordifolium, L. cuneiforme, L. erubescens, L. glabrum, L. reflexum, L. vestitum). Seeds of each species were scarified, soaked in water and incubated at 15 combinations of diurnal low (16h) and high (8h) temperatures. The results indicated that Leucospermum seeds generally require alternating temperatures for germination. Regression analysis of germination percentage responses were used to estimate provisional optimum low [TO(LOW)] and optimum high [TO(HIGH)] temperature requirements for individual species. These requirements differed markedly among species, and across species they averaged 9.9 and 21.2°C, respectively. Individual requirements correlated positively with mean late autumn air temperatures obtained from weather stations near the natural habitats of species. We conclude that a diurnal alternating temperature requirement is a character syndrome in Leucospermum in which the TO(LOW) and TO(HIGH) components are narrowly adaptive, independent and genetically stable characters relating to the known ecophysiological roles of low and high temperature requirements (Brits, Cutting, Brown and Van Staden, 1995). Ecological and adaptive roles of these requirements are compared with those in some persistent small-seeded soil-stored seed banks. © 2014 South African Association of Botanists.


van Schalkwyk D.L.,Stellenbosch University | McMillin K.W.,Stellenbosch University | McMillin K.W.,Louisiana State University | Booyse M.,Biometry Unit | And 2 more authors.
Meat Science | Year: 2011

Differences and consumer acceptability of matured salami produced from game species were evaluated. The pH of the salami differed (p<0.05) with springbok salami having the highest mean pH value. No differences (p>0.05) were observed among the species for aw, shear force, gumminess or cohesiveness. Microbiological counts of the game salami differed for coliform (p<0.05) but not for E. coli (p>0.05) counts. The most distinctive characteristics observed by the quantitative descriptive analyses were smoky, salty, pepper and salami flavour, combined with a smoky, salami aroma. Game flavour was not perceived as a strong attribute during the sensory analyses. Gemsbok salami was strongly associated with the attribute colour as described by the male and female consumer panels. The springbok salami scored the lowest for both colour and taste. Salami produced from gemsbok, kudu and zebra were superior to springbok salami. © 2010 The American Meat Science Association.


Krecek R.C.,Ross University School of Medicine | Krecek R.C.,University of Johannesburg | Mohammed H.,University of Trinidad and Tobago | Michael L.M.,Bayer Pty Ltd | And 5 more authors.
PLoS ONE | Year: 2012

There is a high prevalence of Taenia solium taeniosis/cysticercosis in humans and pigs in the Eastern Cape Province (ECP) of South Africa. The objective of this study was to identify risk factors of porcine cysticercosis in select districts of the ECP. Data were collected in 2003 by interviewing 217 pig producers from the area. Blood samples were collected from 261 of their pigs, which were tested using two enzyme-linked immunosorbent assays (ELISA) for the presence of antibodies to cysticercosis. Frequencies of both owner- and pig-level characteristics were determined. For pig-level analysis, all bivariable and multivariable associations were determined using the surveylogistic procedure of the SAS/STAT® software to accommodate for the intraclass correlation that exists for clusters of pigs within one owner and for clusters of owners within a district. All tests for significance were performed at the α = 0.05 level, and adjusted odds ratios (aOR) and 95% confidence intervals (CI) were determined. Among the respondents, 48% of their households lacked a latrine, 98% slaughtered pigs at home, and 99% indicated that meat inspection services were not available. On bivariable analysis, there was a significant association between porcine infection and district (p = 0.003), breed (p = 0.041) and the absence of a latrine (p = 0.006). On multivariable analysis, the absence of a latrine was the only variable significantly associated with porcine infection (aOR = 1.89; 95% CI = 1.07, 3.35) (p = 0.028). The increased odds of porcine infection with households lacking a latrine contributes to our understanding of the transmission of this parasite in the ECP. Determining and addressing the risk factors for T. solium infection can potentially lower the very high prevalence in humans and pigs in this endemic area. © 2012 Krecek et al.


Catania G.,Care Network | Catania G.,University of Genoa | Beccaro M.,Academy of science of Palliative Medicine | Costantini M.,Palliative Care Unit | And 4 more authors.
Palliative Medicine | Year: 2015

Background: One of the most crucial palliative care challenges is in determining how patient' needs are defined and assessed. Assessing quality of life has been defined as a priority in palliative care, and it has become a central concept in palliative care practice. Aim: To determine to what extent interventions focused on measuring quality of life in palliative care practice are effective in improving outcomes in palliative care patients. Design: Systematic review according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and hand searches. Data sources: MEDLINE, CINAHL, EMBASE, PsycINFO, and the Cochrane Library were searched for articles published until June 2012, and through hand searching from references lists of included articles. Only studies that included adult palliative care patients, in any palliative care clinical practice setting of care, and with an experimental, quasi-experimental, or observational analytical study design were eligible for inclusion. All studies were independently reviewed by two investigators who scored them for methodological quality by using the Edwards Method Score. Results: In total, 11 articles (of 8579) incorporating information from 10 studies were included. Only three were randomized controlled trials. The quality of the evidence was found from moderate to low. Given a wide variability among patients' outcomes, individual effect size (ES) was possible for 6 out of 10 studies, 3 of which found a moderate ES on symptoms (ES = 0.68) and psychological (ES = 0.60) and social (ES = 0.55) dimensions. Conclusion: Effectiveness of interventions focused on quality-of-life assessment is moderate. Additional studies should explore the complexity of the real palliative care world more accurately and understand the effects of independent variables included in complex palliative care interventions. © The Author(s) 2014.


PubMed | Academy of science of Palliative Medicine, University of Genoa, Biometry Unit and Palliative Care Unit
Type: Journal Article | Journal: Palliative medicine | Year: 2014

One of the most crucial palliative care challenges is in determining how patient needs are defined and assessed. Assessing quality of life has been defined as a priority in palliative care, and it has become a central concept in palliative care practice.To determine to what extent interventions focused on measuring quality of life in palliative care practice are effective in improving outcomes in palliative care patients.Systematic review according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and hand searches.MEDLINE, CINAHL, EMBASE, PsycINFO, and the Cochrane Library were searched for articles published until June 2012, and through hand searching from references lists of included articles. Only studies that included adult palliative care patients, in any palliative care clinical practice setting of care, and with an experimental, quasi-experimental, or observational analytical study design were eligible for inclusion. All studies were independently reviewed by two investigators who scored them for methodological quality by using the Edwards Method Score.In total, 11 articles (of 8579) incorporating information from 10 studies were included. Only three were randomized controlled trials. The quality of the evidence was found from moderate to low. Given a wide variability among patients outcomes, individual effect size (ES) was possible for 6 out of 10 studies, 3 of which found a moderate ES on symptoms (ES = 0.68) and psychological (ES = 0.60) and social (ES = 0.55) dimensions.Effectiveness of interventions focused on quality-of-life assessment is moderate. Additional studies should explore the complexity of the real palliative care world more accurately and understand the effects of independent variables included in complex palliative care interventions.


Venter G.J.,Onderstepoort Veterinary Institute | Venter G.J.,University of Pretoria | Boikanyo S.N.B.,Onderstepoort Veterinary Institute | Majatladi D.M.,Onderstepoort Veterinary Institute | Morey L.,Biometry Unit
Medical and Veterinary Entomology | Year: 2016

To implement risk management against diseases transmitted by species of Culicoides Latreille, 1809 (Diptera: Ceratopogonidae), it is essential to identify all potential vectors. Light traps are the most commonly used tool for the collection of Culicoides midges. Given the indiscriminate artificial attraction of light, traps will collect all night-flying insects rather than only livestock-associated Culicoides midges. Factors that may increase the efficacy of traps, especially for livestock-associated Culicoides midges, require investigation. In the present study, results obtained with Centers for Disease Control (CDC) and Onderstepoort light traps baited with carbon dioxide (CO2) were compared with those of unbaited controls. Comparisons were made using two replicates of a 4 × 4 randomized Latin square design. With both trap types, the mean numbers of Culicoides midges collected in 16 baited traps were higher than those caught in 16 unbaited traps. Although exceptionally low numbers were collected with the CDC traps, the increases in the numbers and frequency of collection of Culicoides imicola Kieffer, 1913 were more pronounced in the CDC traps compared with the Onderstepoort traps. These results indicate that the addition of CO2 may increase the efficiency of these traps for the collection of C. imicola and other livestock-associated Culicoides species. © 2016 The Royal Entomological Society.


Strydom P.E.,Animal Production Institute | Frylinck L.,Animal Production Institute | Smith M.F.,Biometry Unit
Animal | Year: 2011

Cattle breeds indigenous to Africa (Sanga) compare favourably to Bos indicus breeds with regard to adaptation to harsh environments. This study compared the meat quality of three Sanga breeds (Nguni, Tuli and Drakensberger), a Sanga-related breed (Bonsmara) and a B. indicus breed (Brahman) and supported these results with biochemical and histological measurements on the M. longissimus lumborum. Twelve young grain-fed steers of each breed were slaughtered and carcasses were electrically stimulated. All Sanga (and related) breeds, with the exception of the Tuli, had lower Warner-Bratzler shear force (SF) values at 2 and 21 days post mortem compared with the BR (P < 0.05). Measurements related to the calcium-dependent protease system and myofibrillar fragmentation explained the bulk of the variation among breeds, whereas variation in fibre type, sarcomere length and connective tissue properties gave less convincing support. With the exception of the Tuli, Sanga and Sanga-related breeds produced more tender (according to SF) meat than BR, mainly due to favourable calpain-to-calpastatin ratios. Small differences in colour, drip loss and cooking properties were found among breeds (P < 0.05). © The Animal Consortium 2011.


Thiart C.,University of Cape Town | Ngwenya M.Z.,Biometry Unit | Haines L.M.,University of Cape Town
Journal of the Southern African Institute of Mining and Metallurgy | Year: 2014

Kriging is an interpolation technique for predicting unobserved responses at target locations from observed responses at specified locations. Kriging predictors are best linear unbiased predictors (BLUPs) and the precision of the BLUP is assessed by the mean square prediction error (MSPE), commonly known as the kriging variance. Both the BLUP and the MSPE depend on the covariance function describing the spatial correlation between locations and on specific parameters. The parameters are usually treated as known, whereas in practice they invariably have to be estimated and the empirical BLUP (that is, the EBLUP) so obtained. The empirical or estimated mean square prediction error (EMSPE), or the so called 'plug-in' kriging variance estimator, underestimates the true kriging variance of the EBLUP, at least in general. In this paper five estimators for the kriging variance of the EBLUP are considered and compared by means of a simulation study in which a Gaussian distribution for the responses, an exponential structure for the covariance function, and three levels of spatial correlation - weak, moderate, and strong - are adopted. The Prasad-Rao estimator obtained using restricted or residual maximum likelihood (REML) is recommended for moderate and strong spatial correlation and the Kacker-Harville estimator for weak correlation in the random fields. © The Southern African Institute of Mining and Metallurgy, 2014.


PubMed | Biometry Unit and Onderstepoort Veterinary Institute
Type: Journal Article | Journal: Medical and veterinary entomology | Year: 2016

To implement risk management against diseases transmitted by species of Culicoides Latreille, 1809 (Diptera: Ceratopogonidae), it is essential to identify all potential vectors. Light traps are the most commonly used tool for the collection of Culicoides midges. Given the indiscriminate artificial attraction of light, traps will collect all night-flying insects rather than only livestock-associated Culicoides midges. Factors that may increase the efficacy of traps, especially for livestock-associated Culicoides midges, require investigation. In the present study, results obtained with Centers for Disease Control (CDC) and Onderstepoort light traps baited with carbon dioxide (CO2 ) were compared with those of unbaited controls. Comparisons were made using two replicates of a 4 4 randomized Latin square design. With both trap types, the mean numbers of Culicoides midges collected in 16 baited traps were higher than those caught in 16 unbaited traps. Although exceptionally low numbers were collected with the CDC traps, the increases in the numbers and frequency of collection of Culicoides imicola Kieffer, 1913 were more pronounced in the CDC traps compared with the Onderstepoort traps. These results indicate that the addition of CO2 may increase the efficiency of these traps for the collection of C. imicola and other livestock-associated Culicoides species.

Loading Biometry Unit collaborators
Loading Biometry Unit collaborators