Masters Degrees (Animal, Wildlife and Grassland Sciences)

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Browsing Masters Degrees (Animal, Wildlife and Grassland Sciences) by Author "De Waal, H. O."

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    Determination of some blood parameters in the African lion (Panthera leo)
    (University of the Free State, 2008-11) Erasmus, Heidi Louise; Schwalbach, L. M. J.; De Waal, H. O.
    The goal of this study was to generate a database of laboratory results for African lion (Panthera leo) blood to obtain reliable reference ranges to augment what is currently available in literature. Also to investigate the possibility of age and sex having an influence on these reference ranges. The specific objectives of this study were: o to determine reference values for haematological and biochemical blood variables for lions bred in captivity, as a function of age and sex; o to evaluate the Beckman Coulter Ac•T 5diff Haematology Analyzer for lion differential white blood cell analyses; o to determine morphometric measurements and establish reference growth curves (and range reference values) for lions bred and reared in captivity as a function of age and sex; o to determine reference values for some practical and meaningful body measurements and their correlations. This study was conducted on three lion ranches in the Free State province and at the Bloemfontein Zoological Gardens (Bloemfontein Zoo) with captive lions (Panthera leo) of both sexes and ages ranging from three months to nine years. Lions were divided into four age groups according to published literature. Animals were chemically immobilized (darted) with Zoletil® 100 at 4 to 5mg/kg in their holding camps and moved to a shaded place as soon as the drug had taken its full effect. Blood was collected into three different types of blood collection tubes and body measurements were taken. This was all done as fast as possible before the effect of the immobilizing drug could wear off. In some cases it was necessary to give an animal a top-up dose to prevent it from waking up too quickly. Animals were moved back to their holding camps to fully recover from the immobilization. Blood analyses done with the Ac•T 5diff Haematology Analyzer from Beckman Coulter® for haematological parameters was conducted within 30 minutes after blood collection. Blood for biochemistry parameters was centrifuged, serum collected and cryo preserved at -20°C until it could be taken to the laboratory for analyses. Blood smears were made on the lion ranches and Bloemfontein zoo immediately after the analysis with the Ac•T 5diff Haematology Analyzer, fixed and packed for transport to the laboratory. At the laboratory the serum was used for biochemistry analyses, using standard laboratory techniques. Blood smears were stained and examined under a light microscope for the differential white blood cell count by means of the manual-visual method. Results were statistically analyzed to determine reference ranges and the influence of age and sex on these reference range values for the different parameters, were considered. Body measurement were also statistically analyzed to determine correlations between body weight and different other measurements. These correlations were then used to determine if it will be possible in a field situation to use the age and sex of an animal together with a certain body measurement to estimate body weight accurately, if actual weighing was not possible. From these analyses it was concluded that age and sex do have an influence on blood analysis and blood reference ranges for the African lion (Panthera leo). Unfortunately, it differs between parameters and there is not one rule to apply. The conclusion could also be made that body weight could be determined by measuring the head length of an animal. More research is warranted to obtain more data set and establish range reference values that can be validated and used with a high degree of confidence in the lion breeding industry.
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    ItemOpen Access
    Feedlot performance of Dorper lambs on Opunti: based diets with different nitrogen sources
    (University of the Free State, 2009-11) Shiningavamwe, Katrina Lugambo; De Waal, H. O.; Schwalbach, L. M. J.; Els, J.
    Three feedlot diets were evaluated with Dorper wether lambs at Bergvlug Experimental Farm, Khomas Region, Namibia. Bergvlug is located about 35 km east of Windhoek. The three treatment diets consisted of a conventional feedlot diet (treatment diet T0) and two Opuntia-based treatment diets (T1 and T2) containing different additional nitrogen sources, namely a non-protein nitrogen (NPN; feed grade urea) or natural protein (sunflower oilcake meal). Treatment diet T0 was based on coarsely ground lucerne hay, yellow maize meal, feed grade urea and molasses meal. The Opuntia-based treatment diets (T1 and T2) were reformulated and part of the lucerne was replaced by sun-dried and coarsely ground Opuntia cladodes at levels of 330 or 300 g/kg. In treatment diet T1 additional nitrogen was included as feed grade urea (non-protein nitrogen; NPN) and for treatment diet T2 the additional nitrogen was included as sunflower oilcake meal (a natural protein). The feed intake and water intake, the growth performance and carcass characteristics of the Dorper wether lambs were evaluated in the feedlot. Forty-five newly weaned Dorper wether lambs, weighing on average about 22 kg, were randomly allocated to the three treatment diets. The 15 Dorper wether lambs per treatment diet were further subdivided into three subgroups or replicates of five lambs each. For the duration of the trial the lambs were kept in small pens in a shaded area (open-sided roofed shed). The Dorper wether lambs were fed the treatment diets until a target average slaughter weight of 35 kg per treatment diet was reached. During the feeding period in the feedlot, one replicate of five Dorper wether lambs per treatment diet was moved from the feedlot pens to metabolism cages for a week every third week to determine their individual daily feed and water intake and apparent digestibility of the three treatment diets. The daily urine and faecal excretions were also monitored. Chemical analysis of the three treatment diets used in this study showed that acid-detergent fibre (ADF), neutral-detergent fibre (NDF), organic matter (OM) and gross energy (GE) have decreased with inclusion of sun-dried and coarsely ground Opuntia cladodes, which is ascribed to the lower ADF, NDF, OM and GE content of the Opuntia cladodes. On the other hand, the ash and lipids increased with inclusion of sun-dried and coarsely ground Opuntia cladodes in the treatment diets. The inclusion of sun-dried and coarsely ground Opuntia cladodes at 330 or 300 g/kg in the treatment diets in general had little or no effect on the feed intake and digestibility of the treatment diets by Dorper wether lambs. Exceptions were observed for the intake and apparent digestibility of ADF and NDF as a result of the difference in fibre content of the treatment diets. Similar water intake and urine excretion were observed for Dorper wether lambs fed any one of the treatment diets during the three cage feeding periods. The results of the study confirmed that the feed intake and apparent digestibility of the treatment diets for Dorper wether lambs were not affected by: (1) the inclusion of sun-dried and coarsely ground Opuntia cladodes at 330 and 300 g/kg; or (2) two nitrogen sources used (NPN or natural protein) in the Opuntia-based diets. Considering the results of the Cage Periods 1 to 3, it can be summarised that the daily intake and apparent digestibility of DM and other chemical constituents of the Dorper wether lambs increased as the trial progressed, regardless of the treatment diets. It suggests that the reticulo-rumen of Dorper wether lambs were getting better adapted over time to the diets and consequently digestibility improved. The average daily gain and feed conversion efficiency of Dorper wether lambs fed the Opuntia-based diet supplemented with natural protein were comparable to those fed the conventional feedlot diet. The Dorper wether lambs fed the Opuntia-based diet supplemented with NPN had a lower growth rate than those fed the conventional feedlot diet and the Opuntia-based diet supplemented with natural protein. Thus, although feed conversion efficiency was not significantly (P>0.05) different among treatment diets, Dorper wether lambs fed the conventional diet and the Opuntia-based diet supplemented with natural protein required less feed to gain weight than those fed the Opuntia-based diet supplemented with NPN. This suggests that supplementing an Opuntia-based feedlot diet with a natural protein source will markedly improve feed efficiency and average daily gain of lambs. This may reduce the feeding period required to reach the target slaughter weight and increase the economic benefit associated with the use of sun-dried and coarsely ground Opuntia cladodes in feedlot diets. Most of the carcass characteristics considered were not significantly different (P>0.05) among treatments. It suggests that carcass quality or grading is not markedly affected by inclusion of sun-dried and coarsely ground Opuntia cladodes in feedlot diets (up to 330 or 300 g/kg) for Dorper wether lambs or by the nitrogen source used to balance the diets. The carcasses of the Dorper wether lambs fed the three different treatment diets fetched very similar prices per kg. However, the Dorper wether lambs fed treatment diet T1, the Opuntiabased diet with the inclusion of feed grade urea (an NPN source), did not reach the average target slaughter weight of 35 kg, even after 91 days in the feedlot. Therefore, their lighter carcasses and poorer carcass grading at slaughter fetched a lower total price per carcass. The results of this study, the fourth study under the auspices of the UFS, opened the prospect of formulating affordable Opuntia-based diets for specific application to ruminant species of different ages and production classes. However, more research is needed to evaluate the growth performance, carcass characteristics and profitability of other small stock breeds and ruminant species fed sun-dried and coarsely ground Opuntia cladodes in feedlot diets, balanced with different nitrogen sources.
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    ItemOpen Access
    The impact of predation on a sheep enterprise in the Free State Province
    (University of the Free State, 2009-11-27) Strauss, Andries Jacobus; De Waal, H. O.; Avenant, N. L.
    The Free State Wool Sheep Project was initiated in 1998 at the Glen Agricultural Institute (AI) and a selection of 280 of the available Merino ewes were randomly divided in the following four production system treatments, namely: · Treatment SL-V(C) Spring Lambing season on Veld with a salt (NaCl) lick only (control) · Treatment SL-V&S Spring Lambing season on Veld with Supplementary feeding · Treatment SL-R&V Spring Lambing season on irrigated Rye-grass (Lolium multiflorum and L. perenne) and veld · Treatment AL-O&V Autumn Lambing season on Oats (Avena sativa) pasture in winter and Veld in summer and spring The broad aim of the Free State Wool Sheep Project was to “develop profitable and sustainable wool farming systems on the resource combination of Glen AI”. However, it was not foreseen at the conceptualization of the Project in 1998 that the impact of predation, mostly by black-backed jackal Canis mesomelas on the sheep flocks at Glen AI would soon reach the high levels experienced in later years. A Merino shearing flock (77 ewes in 2003) and a Dorper flock (219 ewes in 2003) at the Glen AI were also severely impacted by predation. These two flocks were managed in the same way as the Merino ewes in Treatment SL-V(C), therefore, it was decided to include the results of these two flocks also in this study. The impact of predation on reproduction and production performance of sheep flocks (Merino and Dorper) are reviewed and put into perspective for the period 1999 to 2007. Four categories of sheep losses were identified namely: predation, diseases, metabolic disorders or accidents and stock theft. Direct financial losses, veterinary and shearing cost, lick, labour and planted pasture cost were calculated for each of these categories of losses. The calculations were included in the review and served as basis for determining the extent to which financial losses ascribed to predation exceeded the financial losses due to diseases, metabolic disorders or accidents and stock theft. Ewe productivity was negatively influenced by predation. The Merino and Dorper flocks decreased in numbers from 1 130 sheep to 552 sheep over a period of nine years. From 1999 until 2007, a total of 747 lambs were lost to predation before weaning and a total of 1 422 lambs were lost post weaning. The number of reproductive Merino and Dorper ewes that were available for mating declined from 506 ewes in 2003 to 316 ewes in 2007. Some of the ewes in the four Merino production system flocks, the shearing flock, and the Dorper flock could not raise one lamb in a six-year production cycle due to predation. Therefore, it became increasingly difficult to replace older ewes and maintain flock sizes for the respective flocks. The only exception was the Treatment SL-R&V flock, because they were better protected from predation during critical phases in the reproduction cycle. The black-backed jackal specifically, had a big impact on the sheep flocks at the Glen AI (70% of the 730 post-weaning losses from 2003 until 2007). Losses ascribed to predation contributed to 72% of the total annual financial losses, diseases 2%, metabolic disorders or accidental mortalities 20% and stock theft only 6%. Therefore, the financial impact ascribed to predation at an average of R129 562/year overshadowed the losses due to diseases (average R4 337/year), metabolic disorders or accidents (average R35 299/year) and stock theft (average R9 843/year) by a considerable margin. The negative impact of predation on the sheep flocks at the Glen AI made it impossible to evaluate the economical viability and sustainability of the Merinos in the different treatment flocks as envisaged in the protocol of the Free State Wool Sheep Project. Furthermore, a large component of the genetic base of the two sheep breeds at the Glen AI has been lost for the future, due to the effect of predation. An urgent and concerted approach of all role-players in the sheep industry is needed to develop and implement effective predator management programmes to reduce the negative impact of predation.