Genetic variance components for residual feed intake and feed conversion ratio and their correlations with other production traits in beef bulls

Feeding costs of animals is a major determinant of profitability in livestock production enterprises. Genetic selection to improve feed efficiency aims to reduce feeding cost in beef cattle and thereby improve profitability. This study estimated genetic (co)variances between weaning weight and other production, reproduction and efficiency traits. Traits included residual feed intake (RFI), feed conversion ration (FCR), growth (average daily gain (ADG), weaning weight (WW) and shoulder height (SHD)), reproductive (scrotum circumference (SCR)) and profitability traits measured in growth tests of young bulls. The only genetic correlations of significance with WW were those with SHD (0.50) and ADG (0.28). Weaning weight serves as no indication of an animal's production, owing to low genetic correlations with other traits (reproduction or feedlot post-weaning growth efficiency). The heritability estimated for FCR was 0.34 and for RFI 0.31 with a genetic correlation estimate of 0.75 between them. The estimated genetic correlation of profitability (Rand-value) with FCR and RFI were -0.92 and -0.59, respectively. The genetic correlations and expected correlated responses between RFI and FCR with Rand-value suggest that indirect selection for Rand-value through direct selection for FCR and/or RFI will result in slower genetic progress in Rand-value than direct selection. However, where the Rand-value cannot be calculated and/or direct selection for Rand-value is not possible, it would be better to select indirectly for Rand-value through the use of FCR rather than RFI. Key Words: Beef cattle, Feed conversion ratio, Genetic (co)variances, Profitability, Residual feed intake South African Journal of Animal Science Vol.34(4) 2004: 257-26

Genetic relationship between feed efficiency and profitability traits in beef cattle

Genetic selection to improve feed efficiency aims to reduce the cost of feeding costs in beef cattle production and thereby improve profitability. The aim of this study was to estimate genetic (co)variances to compare residual feed intake (RFI) and feed conversion ratio (FCR) with growth, reproductive and profitability traits measured in growth tests of young bulls. The heritability estimated for FCR was 0.34 and for RFI 0.31 with a genetic correlation estimate of 0.75 between the traits. The estimated genetic correlation between profitability and FCR and RFI were -0.92 and -0.59, respectively. The genetic correlations and expected correlated responses between RFI and FCR with post-wean profitability (M-value) suggest that indirect selection for M-value through the direct selection for FCR and/or RFI will result in slower genetic progress in M-value than direct selection for M-value. However, where the M-value cannot be calculated and/or direct selection for M-value is not possible, it would be better to select indirectly for M-value through the use of FCR rather than RFI. South African Journal of Animal Science Supp 2 2004: 50-5

The effect of Black Plastic Mulch on Growth, Production and Root Development of Chenin blanc Vines under dryland conditions

Studies have shown that black plastic used as a mulch at' planting time under conditions of limited or no irrigation, greatly increased the growth of the vines. Although the exposed plastic film deteriorated within two years, the favourable effect persisted to the fifth year after planting, bringing the mulched vines to production a year earlier than the unmulched vines. The advantages of plastic mulch are conservation of soil moisture, more uniform soil temperatures,weed control and less soil compaction. These factors increase root and shoot growth, and improve both survival of the young vines and production. The durability of the plastic film was extended by covering it with a layer of soil, and thus a longer period of weed control was obtained

Applying a model of technology trust to the implementation of a student administration system at a university

Includes bibliographical references (leaves 63-69).This study tested the generalisability of a model of technology trust in human resource information systems (Lippert & Swiercz, 2005) to non-HRIS system implementations. The strength and direction of the relationship of four of the tenconstructs identified by Lippert and Swiercz were examined in a South African environment. The implementation of the PeopleSoft student administration system at the University of Cape Town was researched. Regression analysis showed that a very high percentage (57.6% ) of the dependent variable (technology trust) could beexplained by the variable technology usability. The construct, predisposition to trust, had an insignificant contribution, while organisational trust (10.7%) and organisational culture (19.1%) were the other two constructs that were researched. The relationship between technology trust and implementation success was significant with r = +0.75

Culture, participative decision making and job satisfaction

This study explores the impact of culture on participative decision making (PDM) and job satisfaction (JS) using data obtained from the European Values Study. We parameterise two different cultural variables using principal components analysis: first a continuum based on survival versus self-expression values, and second a continuum based on traditional versus secular-rational values. Application of ordered logistic regression to Likert scales of PDM and JS suggest that greater self-expression in the survival versus self-expression variable enhances both PDM and JS; more traditional values in the traditional versus secular-rational continuum have the same effect.Job satisfaction; participatory decision making; culture

Persistence of attention deficit/ hyperactivity disorder into adulthood: a study conducted on parents of children diagnosed with attention deficit/hyperactivity disorder

No Abstract.South African Psychiatry Review Vol. 10 (2) 2007: pp.93-9

Andragogy : a theoretical overview on learning theories that impact on benchmarking blended learning at the Central Univerity of Technology, Free State

Published ArticleBlended learning has shown enormous growth worldwide during the last decade. Blended learning initiatives expanded rapidly, as technological improvement and a greater demand from learners arose as a result of the need for life-long learning and changing demands in the world of work. Many higher education institutions use blended learning as an alternative for or additional to conventional face-to-face education. The changing needs of learners, and especially adults, forced institutions to upgrade their traditional courses and increasingly make use of technologically enhanced courses. The research problem encompasses the fact that the growth of blended learning poses many problems to higher education institutions, as the delivery by means of technology is complex. Many higher learning institutions were not prepared adequately to deliver education by using blended learning and did not have the required systems in place. The greatest concern was that staff was not familiar with the technology or its use and that the particular demands of staff arrangements to engage in blended learning programs were not taken into account. It appears that institutions did not plan or have systems and guidelines in place to implement programs at a distance using blended learning technology. Another concern was that most of the programs held traditional approaches and has not been adapted to suit the particular characteristics and needs of distance education by taking the planning, development and review of such programs into consideration. As part of ongoing research at the Central University of Technology, Free State appropriate research had to be undertaken. Consequently the following research question emanated from the research problem: Within the context of higher education in South Africa, what framework underpinned by andragogy, national education policies and blended learning theory, will benchmark and support the implementation of blended learning at the Central University of Technology, Free State

Andragogy : a theoretical overview on learning theories that impact on benchmarking blended learning at the Central Univerity of Technology, Free State

Published ArticleBlended learning has shown enormous growth worldwide during the last decade. Blended learning initiatives expanded rapidly, as technological improvement and a greater demand from learners arose as a result of the need for life-long learning and changing demands in the world of work. Many higher education institutions use blended learning as an alternative for or additional to conventional face-to-face education. The changing needs of learners, and especially adults, forced institutions to upgrade their traditional courses and increasingly make use of technologically enhanced courses. The research problem encompasses the fact that the growth of blended learning poses many problems to higher education institutions, as the delivery by means of technology is complex. Many higher learning institutions were not prepared adequately to deliver education by using blended learning and did not have the required systems in place. The greatest concern was that staff was not familiar with the technology or its use and that the particular demands of staff arrangements to engage in blended learning programs were not taken into account. It appears that institutions did not plan or have systems and guidelines in place to implement programs at a distance using blended learning technology. Another concern was that most of the programs held traditional approaches and has not been adapted to suit the particular characteristics and needs of distance education by taking the planning, development and review of such programs into consideration. As part of ongoing research at the Central University of Technology, Free State appropriate research had to be undertaken. Consequently the following research question emanated from the research problem: Within the context of higher education in South Africa, what framework underpinned by andragogy, national education policies and blended learning theory, will benchmark and support the implementation of blended learning at the Central University of Technology, Free State

The effect of Charolais and Hereford sires and straightbred and crossbred dams on pre-weaning growth of calves

Weaning performance of calves sired by Charolais and Hereford on dams of Angus, Bonsmara and Hereford and various crossbred dam combinations was compared. Charolais sired calves were on average 5 kg heavier at birth and 20 kg heavier at weaning than Hereford sired calves. Among the three straightbred dam breeds, the Bonsmara weaned calves that were approximately 6% heavier than both the Angus and the Hereford calves. The use of crossbred dams having intermediate levels of Charolais composition is suggested in crossbreeding programmes in intensive production systems based on cultivated pastures under irrigation. South African Journal of Animal Science Vol.32(1) 2002: 38-4

Optical aid for placing composite material (prepregs) in a mould

CITATION: Van Der Westhuizen, J. & Schreve, K. 2018. Optical aid for placing composite material (prepregs) in a mould. South African Journal of Industrial Engineering, 29(1):35-48, doi:10.7166/29-1-1612.The original publication is available at http://sajie.journals.ac.zaENGLISH ABSTRACT: Increased industrial use of composite materials for manufacturing strong lightweight components stimulates endeavours for more efficient assembly methods. This study attempted to find an optimal method to provide optical aid for the placement of pre-impregnated reinforcing fabric (prepregs). A novel approach to optical assistance for the placement of prepregs was designed to be straightforward and affordable. The developed system meets industry standards for accuracy, and provides the solution at a cost many times less than existing solutions. The findings allow companies in the composite material industry to eliminate prepreg layup errors at an affordable price.AFRIKAANSE OPSOMMING: ’n Toename in die gebruik van saamgestelde materiale vir vervaardiging van sterk, liggewig komponente stimuleer pogings vir meer effektiewe samestellingsmetodes. Die doel van hierdie studie was om ’n optimale metode te vind vir die optiese ondersteuning in die plasing van vooraf geïmpregneerde materiaal. ’n Nuwe benadering vir optiese ondersteuning vir die plasing van vooraf geïmpregneerde materiaal is ontwerp om bekostigbaar en eenvoudig te wees. Die ontwikkelde benadering voldoen aan die industrie se standaarde vir akkuraatheid, en bied die oplossing teen ’n prys wat aansienlik minder is as bestaande oplossings. Die bevindinge bied besighede in die saamgestelde materiaal industrie met ’n bekostigbare oplossing om vooraf impregnering plasing foute te elimineer.http://sajie.journals.ac.za/pub/article/view/1612Publisher's versio