I. Groenewald - Academia.edu (original) (raw)

Papers by I. Groenewald

South African Journal Of Animal Science

African journal of agricultural research

Shredded citrus (Citrus sinensis) leaves were treated with: Control (no additive), liquid whey an... more Shredded citrus (Citrus sinensis) leaves were treated with: Control (no additive), liquid whey and Lactobacillus buchneri (LB) and ensiled in 1.5 L anaerobic jars (15 jars/treatment). Jars were opened on day 2, 5, 10, 20 and 40 post ensiling for analysis of nutritive value and silage fermentation characteristics. In addition, samples of day 40 were subjected to a 5 day aerobic test where CO 2 production was measured. After 40 days of ensiling, inoculation reduced (P<0.05) silage pH, butyric acid and ammonia-N while increasing acetic and lactic acids content compared to control. The aerobic stability of silage was improved (P<0.05) with whey and LB as indicated by lower CO 2 production compared to control. It was concluded that silage produced from citrus leaves was poorly fermented as indicated by high pH and low lactic acid contents.

African journal of agricultural research

This study was conducted to determine the ensiling potential of potato hash (PH) with poultry lit... more This study was conducted to determine the ensiling potential of potato hash (PH) with poultry litter (PL) and hay as absorbents, and whey and molasses as additives. Mixtures of 800 g/kg PH and 200 g/kg of either PL or hay were produced and treated with no additive, whey and molasses. The experiment was conducted in a 2 absorbents × 3 additives factorial design. Mixtures were ensiled in 1.5 L anaerobic jars, and sampling was done on days 0, 4, 10, 20, 40, 60, and 90 for the determination of fermentation quality and nutritive value. Further, an aerobic stability test was done on day 90 by exposing silage to air for 5 days. Ensiling PH with hay compared to PL resulted in a better quality silage as indicated by (P < 0.05) improved fermentation characteristics and chemical composition. Although, the addition of PL significantly increased (P < 0.05) the crude protein (CP) and ash contents in PH silage, fermentation, and the aerobic stability of silage was poor and could influence an...

Irrigation schemes were first developed in South Africa during the apartheid era for commercial f... more Irrigation schemes were first developed in South Africa during the apartheid era for commercial farming. The schemes were gradually introduced in the small-scale farming communities of former homelands for commercial purposes, improving household food security and alleviating poverty. Revitalization of small scale irrigation schemes is central in the Integrated Sustainable Rural development Strategy as an opportunity for rural communities to improve their livelihood. The three government intervention initiatives analyzed in this study include: tenure security, agribusiness development and infrastructure development. This study is different from previous studies in that it analyses the impact of specific intervention variables that government is implementing as part of revitalization. A case study of Tswelopele Irrigation Scheme, which is situated in Sekhukhune District, was used for this study. The population of the study was composed of all 84 farmers of Tswelopele irrigation schem...

Animal Feed Science and Technology

The aim of this study was to determine effects of ensiling whole crop maize with the bacterial in... more The aim of this study was to determine effects of ensiling whole crop maize with the bacterial inoculants Bonsilage mais flussig (BMF) and Lalsil Fresh LB (LFLB) on fermentation, aerobic stability and growth of lambs. Whole crop maize (288 DM g/kg) was ensiled with no additive, BMF or LFLB for 60 days in 1.5 l jars and 3 months in 210 l drums. To follow the fermentation dynamics during ensiling, 1.5 l jars were opened on days 0, 4, 10, 21 and 60 of ensiling for sampling and analysed for pH, water-soluble carbohydrates (WSCs), volatile fatty acids (VFAs), lactic acid, ammonia-N, dry matter (DM), organic matter (OM), metabolizable energy (ME), crude protein (CP), ether extract (EE), ADF and NDF. The aerobic stability of silage was determined by opening jars on day 60 and putting silage in an aerobic environment until day 65. After 3 months of ensiling the 210 l drums were opened, sampled and analysed as for the laboratory scale silos. Silages were fed to 24 South African Dorper lambs ...

South African Journal of Animal Science, 2001

... 200 A survey of small-scale cattle farming systems in the North West Province of South Africa... more ... 200 A survey of small-scale cattle farming systems in the North West Province of South Africa LM Schwalbach 1 , IB Groenewald 2 and CB Marfo 2# ... SAS, 1990. Statistical Analysis Systems user's guide (Version 6, 3rd Ed.). SAS Institute Inc., Cary, North Carolina, USA. ...

Molecular and Cellular Probes, 1998

A subset of probands from 11 South African families with clinical and/or biochemical features of ... more A subset of probands from 11 South African families with clinical and/or biochemical features of variegate porphyria (VP), but without the known protoporphyrinogen oxidase (PPOX) gene defects identified previously in the South African population, were subjected to mutation analysis. Disease-related mutation(s) could not be identified after screening virtually the entire PPOX gene by heteroduplex single-strand conformation polymorphism analysis (HEX-SSCP), although three new sequence variants were detected in exon 1 of the gene in three normal controls. The presence of these single base changes at nucleotide positions 22 (C/G), 27 (C/A) and 127 (C/A), in addition to the known exon 1 polymorphisms I-26 and I-150, indicates that this untranslated region of the PPOX gene is particularly mutation-prone. Furthermore, microsatellite markers flanking the PPOX and alpha-1 antitrypsin (PI) gene, on chromosomes 1 and 14, respectively, were used to assess the probability of involvement of these loci in disease presentation. Common alleles transmitted from affected parent to affected child were determined where possible in the mutation-negative index cases. Allelic frequencies of these &amp;lt;disease-associated&amp;gt; alleles were compared to findings in the normal population, but no predominant disease-associated allele could be identified. Co-segregation of a specific haplotype with the disease phenotype could also not be demonstrated in a large Afrikaner family. It is concluded that further studies are warranted to determine the genetic factor(s) underlying the autosomal dominant pattern of inheritance in molecularly uncharacterized cases showing clinical symptoms of an acute porphyria.

Molecular and Cellular Probes, 2001

Five single nucleotide polymorphisms (SNPs) in the protoporphyrinogen oxidase gene (PPOX) were us... more Five single nucleotide polymorphisms (SNPs) in the protoporphyrinogen oxidase gene (PPOX) were used for inter-population comparisons of six South African populations and two non-South African Caucasian populations. Novel polymorphisms identified in the promoter region and exon 11 of the PPOX gene, as well as three known variants in exon 1 and intron 2, were analysed using single-strand conformation polymorphism (SSCP) and restriction enzyme analyses. Significant population differences were found for four of the five polymorphisms analysed. A G-to-A transition was found at nucleotide position -1081 and is the first polymorphism to be identified in the 5&amp;amp;amp;#39; promoter region of the gene. A novel A-to-C substitution at nucleotide position 3880 in exon 11 was not detected in subjects of European descent. This study represents the first inter-population comparison of allelic variation at the PPOX locus. The significant differences observed between populations demonstrate the importance of population considerations when marker association studies are performed at this locus.

Human Molecular Genetics, 1996

Human Genetics, 1995

We report a highly polymorphic, sequence-tagged microsatellite site (STMS) at the D5S99 locus tha... more We report a highly polymorphic, sequence-tagged microsatellite site (STMS) at the D5S99 locus that was previously identified by a less informative restriction fragment length polymorphism (RFLP). This marker, which was also localized to the physical map of chromosome 5q by fluorescent in situ hybridization (FISH), should assist in the precision mapping of genes in the area 5q33-34.