Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Over the last few decades various authors have reported the influence of day old chick quality on integrated broiler industries. Although various methods of determining chick quality have been reported, defining a good or a first grade day old chick can be problematic as it involves many subjective measurements. Incubation temperature (embryo temperature) is probably the biggest, most influential factor during incubation on chick quality. High temperatures cause the most damage. It leads to poor growth, stress, black buttons, threads, weak chicks, chicks with poorly erupted down that are bleached in appearance, low hatchability, late embryonic death and early broiler mortality. This trial was designed to test whether 37.2, 37.4 or 37.5ºC was the optimum incubation temperature for hatching Hybro G+ chicks with superior quality. The parameters that were measured were the chick length, bodyweight, and the yolk residue of the day old chicks of the flocks set at different setter temperatures. After hatching, 1 440 chicks (480 chicks per temperature treatment) were placed at a broiler facility where the daily mortalities, weekly bodyweight gain and feed conversion were recorded and calculated. The age of the breeder flock had a significant effect on all three parameters measured in the incubation trial with p values of <0.001, <0.001 and 0.005 respectively. There were no significant differences in chick quality parameters due to different incubation temperatures. The age x temperature interaction could be attributed to the large influence of the age of the breeder on egg size and consequently chick parameters. The results could be related to the fact that bigger eggs from older breeder flocks have higher initial egg mass, which will result in heavier embryos and thus converted to a larger day old chick. The performance trial performed after the incubation trial showed no significant effect of the incubation temperature on 7-day and daily mortalities, weekly bodyweight gain and feed conversion efficiency to 42 days of life. The lack of effects observed in these trials could be attributed to the small range of temperatures used in addition to the difficulties brought about the use of multi-stage incubators.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1956 A43 / Master of Science

Call number: LD2668 .T4 1956 G53 / Master of Science

Call number: LD2668 .T4 1984 H37 / Master of Science

Call number: LD2668 .T4 1985 K343 / Master of Science

Estuaries are among the most productive and diverse of aquatic habitats supporting a rich variety of plants and animals. They are nursery areas for many species of fish harvested by recreational and subsistence anglers. The Swartkops River Estuary (SRE) is situated approximately 10 km north-east of Port Elizabeth and the only major well-preserved estuary within a city, thus unique to South Africa. The SRE is surrounded by highly urbanized and industrialized regions in the Eastern Cape. The aim of this study was to determine and interpret the presence, levels, and distribution of selected priority pollutants in the food web of the SRE. Different components within the SRE were analysed for the presence of environmental contaminants. Seven sites were selected, some coinciding with previous studies in the SRE. Three of these sites are major discharge points that discharge directly into the estuary. Sediment, mud prawn, sand gobies, bird eggs, and various fish species were analysed. Samples were collected in the middle and lower reaches of the estuary, the areas known to receive major pollution loads from neighbouring sources. Heavy metals found in the sediments were compared to previous studies. Bottom sediments and organisms surrounding major discharge points showed higher concentrations of pollutants and compared to previous studies, these concentrations seem to be increasing. Due to biomagnification, higher concentrations were generally found in the top predators although certain elements did not show this trend. Some heavy metal concentrations found in the fish exceeded of the food guidelines and may in turn pose a threat for subsistence users of the SRE. There are indications of multiple different pollution sources. Bird eggs had detectable quantities of polychlorinated biphenyls, but its implications need more investigation. / MSc (Zoology), North-West University, Potchefstroom Campus, 2014

Estuaries are among the most productive and diverse of aquatic habitats supporting a rich variety of plants and animals. They are nursery areas for many species of fish harvested by recreational and subsistence anglers. The Swartkops River Estuary (SRE) is situated approximately 10 km north-east of Port Elizabeth and the only major well-preserved estuary within a city, thus unique to South Africa. The SRE is surrounded by highly urbanized and industrialized regions in the Eastern Cape. The aim of this study was to determine and interpret the presence, levels, and distribution of selected priority pollutants in the food web of the SRE. Different components within the SRE were analysed for the presence of environmental contaminants. Seven sites were selected, some coinciding with previous studies in the SRE. Three of these sites are major discharge points that discharge directly into the estuary. Sediment, mud prawn, sand gobies, bird eggs, and various fish species were analysed. Samples were collected in the middle and lower reaches of the estuary, the areas known to receive major pollution loads from neighbouring sources. Heavy metals found in the sediments were compared to previous studies. Bottom sediments and organisms surrounding major discharge points showed higher concentrations of pollutants and compared to previous studies, these concentrations seem to be increasing. Due to biomagnification, higher concentrations were generally found in the top predators although certain elements did not show this trend. Some heavy metal concentrations found in the fish exceeded of the food guidelines and may in turn pose a threat for subsistence users of the SRE. There are indications of multiple different pollution sources. Bird eggs had detectable quantities of polychlorinated biphenyls, but its implications need more investigation. / MSc (Zoology), North-West University, Potchefstroom Campus, 2014

Microvitellogenin is a female specific yolk protein from the tobacco hornworm moth Manduca sexta. A cDNA library was constructed from poly (A)⁺ RNA isolated from adult female fat body. cDNA clones of mRNA for microvitellogenin were isolated by screening the cDNA library with antiserum against microvitellogenin. The results of Northern blot analysis and hybrid selection indicated that the cDNA clone was specific for microvitellogenin. The complete nucleotide sequence of the 834 base pair cDNA insert has been determined by the dideoxy chain termination method. The deduced amino acid sequence was compared with the N-terminal sequence determined by Edman degradation, an amino terminal extension of 17 amino acids appeared to be a signal peptide. The cDNA sequence predicts that the mature microvitellogenin is a protein of 232 amino acids with a calculated molecular weight of 26,201. A comparison of the translated amino acid sequence with the sequences in National Biomedical Research Foundation protein library did not establish any sequence similarity with known proteins. The microvitellogenin gene begins to be expressed in the fat body on the first day of the wandering (prepupal) females as determined by using the cDNA insert as a probe to hybridize with the mRNA for microvitellogenin. The cDNA probe was also used to screen a genomic library of M. sexta, yielding three genomic clones for microvitellogenin. One of them was characterized and it contained the complete microvitellogenin gene. The gene sequence was determined. Comparison to the cDNA sequence showed that the microvitellogenin gene contains an intron near the 5'-end of the non-coding region. The 5'-flanking sequence of the gene has been compared to the same regions of yp genes of Drosophila and vitellogenin genes of locust, some similar sequences have been observed and discussed.

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