No description available.

Methane emissions of 60 steers (321 ± 14 kg) fed isocaloric forage diets differing in crude protein (CP) content were measured at ambient daily temperatures averaging -17.5°C to determine if increased nitrogen status, measured by blood urea nitrogen (BUN), decrease CH4 as a percent of gross energy intake (% GEI) from backgrounding cattle. Average BUN concentrations (mmol L-1) were 0.81, 1.82, 3.05 and 3.51 (SE ± 0.108) for diets with 6.9% (low), 10.3% (adequate for rumen microbes), 11.1% (adequate for muscle growth) and 13.6% (excessive) CP respectively. Methane (% GEI) emissions decreased with increasing CP over time (P=0.04). Increasing CP content increased BUN levels and decreased methane emissions (% GEI). Although models were developed to predict CH4 emissions (% GEI) from steers and cows using a backward-elimination process, BUN accounted for only 0.7 to 5.7% of the partial R2 and therefore has limited value when modelling methane emission predictions. / February 2016

The occipital bun, a distinctive convexity of the occipital squama, is often considered to be a uniquely derived Neandertal trait. Some scholars, however, consider the occipital morphology found in some early modern and extant human crania (often described as “hemi-buns”) to be homologous with Neandertal occipital buns. A number of hypotheses have been proposed to explain occipital bun/hemi-bun development, including neck muscle function, head carriage, brain growth timing, and cranial base cartilage growth timing, as well as braincase and facial integration. The feature, however, has never before been metrically quantified in a large subadult sample or studied in a well-documented growth series. The primary goal of this dissertation, therefore, was to assess hemi-bun growth and development in a combined comparative sample of extant humans amassed from the following growth series: the University of Toronto Burlington Growth Study, the Iowa Facial Growth Study, the Oregon Growth Study, the University of Oklahoma Denver Growth Study, the Wright State University Fels Longitudinal Study, and the Michigan Growth Study. Cephalograms from these studies facilitated the collection of longitudinal cranial growth and development data. In total, measurements were collected from 468 cephalograms representing 16 males and 10 females. Measured subjects represented the ends of the range of variation in adult midsagittal occipital bone shape, including subjects with defined hemi-buns, as well as subjects lacking all evidence of hemi-bun morphology. Frontal and lateral cephalograms were measured for each subject at 9 age points, spanning from 3.0 to 20.4 years of age. A total of 16 landmarks and 153 sliding semi-landmarks were digitized at each age point. Geometric morphometric analyses, including relative warps analysis and two-block partial least squares analysis, were conducted to assess patterns of cranial covariation and sexual dimorphism in occipital bone growth and possible attendant variation in occipital bun development or absence. In both bunned and non-bunned subjects, midsagittal occipital shape was found to be established very early in ontogeny, and then to remain largely unchanged between 3 years of age and adulthood. This result contradicts previous developmental hypotheses, which posit that occipital bunning results from a pattern of late posteriorly-directed brain growth. No evidence of sexual dimorphism in hemi-bun shape was found to exist in this extant human sample; however, defined hemi-buns were found to covary significantly with an elongated and low midsagittal neurocranial vault in both sexes. Other aspects of cranial morphology, including cranial and basicranial breadth, midcoronal vault shape, and basicranial angle, did not covary significantly with occipital bun morphology at any of the sampled age points. These results reveal that occipital bunning, at least in this sample, is not a discrete trait, but instead develops along a continuum in association with a distinct pattern of neurocranial elongation. Previous studies have suggested that Neandertal occipital buns are similarly associated with elongated cranial vaults. While more work must be done to quantify occipital bun morphology in fossil subadults, this study finds no evidence to disprove the developmental homology of the feature in modern humans and Neandertals, and therefore further undermines the idea that occipital bunning is a unique Neandertal trait.

Ruminants have a unique ability to acquire protein from non-protein nitrogen (NPN) sources, and to recycle nitrogen back into the rumen, instead of excreting all of it via the urine, faeces and milk. However, a high concentration of blood urea nitrogen (BUN) has a negative influence on conception. Additionally, a high dietary nitrogen intake poses a challenge to the environment in the form of ammonia emissions, eutrophication and bad odours. This calls for strategies to reduce the environmental impact of livestock production. Variation exists in the ability of cattle to recirculate nitrogen between as well as within cattle breeds. The purpose of this study was to investigate the effects of BUN concentration on reproductive performance in beef heifers under different management systems in South Africa. Serum samples from 369 Bonsmara heifers were taken in November and December 2010 to determine the BUN concentrations prior to the onset of the breeding season. Heifers were from five herds with different levels of protein supplementation during the weeks before the commencement of the breeding season. Body mass, age, body condition score (BCS) and reproductive tract score (RTS) were recorded at the same time as BUN concentration. Trans-rectal ultrasound and/or-palpation was performed four to eight weeks after the three-month breeding season to detect and estimate the stage of pregnancy. Days to pregnancy (DTP) was defined as the number of days from the start of the breeding season until a heifer was successfully mated. Logistic regression and Cox proportional hazards survival analysis were performed to estimate the effect of BUN concentration on subsequent pregnancy and DTP respectively, while stratifying by herd and adjusting for potential confounders. The correlations between BUN concentration, BCS and RTS were estimated using Spearman’s rho. Pearson correlations were used for the normally distributed variables of age and body mass. BUN concentration was not a significant predictor of pregnancy status but was a significant (P = 0.007) and independent predictor of DTP in heavily and some moderately supplemented herds. As BUN concentration increased, DTP also increased [hazard ratio (HR) = 0.827; 95% CI: 0.721 – 0.949; P = 0.007], while the chance of becoming pregnant decreased, although this was not statistically significant [odds ratio (OR) = 0.882; 95% CI: 0.772 – 1.007; P = 0.063]. Bonsmara heifers with higher BUN concentration, which suggests a better ability to recirculate nitrogen, might be at a disadvantage when the production system includes high levels of RDP supplementation because of this negative impact on reproductive performance. It is proposed that production systems be adapted to avoid selection against animals with an improved ability to recirculate nitrogen. / Dissertation (MMedVet)--University of Pretoria, 2013. / gm2014 / Production Animal Studies / Unrestricted

No description available.

Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2009.

The quality of terrestrial invertebrates as indicators for the detection of ecological change associated with disturbance is widely acknowledged. Invertebrates, at the community level, are often more sensitive to changes than are plants or vertebrates. Both ants and beetles have been studied extensively; changes in ant community composition have been applied successfully as an indication of restoration success. Ants are ideal due to their high abundances and diversity, their ecological importance at all trophic levels, their relative sampling and sorting ease and their sensitivity to ecological change. A detailed understanding of community dynamics greatly facilitates the correct interpretation of signals provided by indicator taxa. Beetles to a great extent, are useful ecological or biodiversity indicators and have been adopted as suitable indicators in environmental monitoring and assessment, as well as to facilitate the evaluation of conservation of biodiversity in landscapes subjected to harvesting. It is well known that ground-dwelling beetle assemblages (especially ground and rove beetles) are sensitive to habitat structure, microclimate and biodiversity management strategies. The use of bio-indicators with regard to land management is becoming increasingly common in ecological studies, because the results obtained can hopefully provide a framework of reference for the prediction of ecosystem response and the means to select the best land use practices. Such predictions will become useful when considering the consequences of ecological perturbations such as fire regimes, bush encroachment, grazing, mining activity, etc. The objectives of this particular study are to determine the effect that past fire treatments may have had on vegetation structure and how ant and beetle assemblages respond to such changes, and what such changes in habitat structure mean in terms of increased bush density. It is expected that the results obtained will provide an indication of the manner in which ecosystem change affects bio-indicator community assemblages, and how this can be applied with regard to future restoration efforts. These organisms were sampled by means of pitfall traps placed within strategic sites varying in vegetation composition and sampled over a number of days. The content of each trap was sorted to genus level, and where possible, to species level and their application of selected invertebrates as indicators of ecosystem change due to veld fires, species richness, abundance and composition determined. The data obtained was analysed statistically using STATISTICA, CANOCO, PRIMER and Microsoft Excel. Four sites with different burn histories were selected: an unburnt site, one burnt in 2002, one burnt in 1997, and one burnt in 1992. Soil characteristics were found to be relatively homogenous throughout all the sample sites, while each of the burn treatment replicates could be characterised by a particular plant structural arrangement. With regards to the ant assemblages, both in terms of species composition and functional group composition, low species diversity appeared to segregate the 1997 burn treatment replicates markedly from the other three burn treatments, with a high degree of species dominance exhibited by Anaplolepis steingroeveri. The ants seem to indicate higher species diversity in the burn treatment sites that had a more diverse vegetation structure. This occurrence however seems to alter over time after a fire incident, before returning to as close to its original state as possible. The beetles, however, displayed very haphazard assemblages, and did not show any discernable significant results that may be used to describe the environmental parameters in question.The reaction of the ants seemed to occur over an extended period of time, with immediate effects of the burn being an increase in non-specialised and opportunistic species abundances, possibly due to a decrease in competition with other species and taxa. Changes in ant assemblages became more apparent after seven years of the burn incident, seemingly linked to structural changes in the plant community. Ant species diversity increased again at the twelve year recovery time, with and associated change in plant habitat structure. The ants thus, in conclusion, show significant results towards indicating a response to habitat change brought on by fire. It is a requirement that this experiment be replicated in order to establish more discernable patterns. Additional recommendations to improve on this study are also discussed. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2009.

The quality of terrestrial invertebrates as indicators for the detection of ecological change associated with disturbance is widely acknowledged. Invertebrates, at the community level, are often more sensitive to changes than are plants or vertebrates. Both ants and beetles have been studied extensively; changes in ant community composition have been applied successfully as an indication of restoration success. Ants are ideal due to their high abundances and diversity, their ecological importance at all trophic levels, their relative sampling and sorting ease and their sensitivity to ecological change. A detailed understanding of community dynamics greatly facilitates the correct interpretation of signals provided by indicator taxa. Beetles to a great extent, are useful ecological or biodiversity indicators and have been adopted as suitable indicators in environmental monitoring and assessment, as well as to facilitate the evaluation of conservation of biodiversity in landscapes subjected to harvesting. It is well known that ground-dwelling beetle assemblages (especially ground and rove beetles) are sensitive to habitat structure, microclimate and biodiversity management strategies. The use of bio-indicators with regard to land management is becoming increasingly common in ecological studies, because the results obtained can hopefully provide a framework of reference for the prediction of ecosystem response and the means to select the best land use practices. Such predictions will become useful when considering the consequences of ecological perturbations such as fire regimes, bush encroachment, grazing, mining activity, etc. The objectives of this particular study are to determine the effect that past fire treatments may have had on vegetation structure and how ant and beetle assemblages respond to such changes, and what such changes in habitat structure mean in terms of increased bush density. It is expected that the results obtained will provide an indication of the manner in which ecosystem change affects bio-indicator community assemblages, and how this can be applied with regard to future restoration efforts. These organisms were sampled by means of pitfall traps placed within strategic sites varying in vegetation composition and sampled over a number of days. The content of each trap was sorted to genus level, and where possible, to species level and their application of selected invertebrates as indicators of ecosystem change due to veld fires, species richness, abundance and composition determined. The data obtained was analysed statistically using STATISTICA, CANOCO, PRIMER and Microsoft Excel. Four sites with different burn histories were selected: an unburnt site, one burnt in 2002, one burnt in 1997, and one burnt in 1992. Soil characteristics were found to be relatively homogenous throughout all the sample sites, while each of the burn treatment replicates could be characterised by a particular plant structural arrangement. With regards to the ant assemblages, both in terms of species composition and functional group composition, low species diversity appeared to segregate the 1997 burn treatment replicates markedly from the other three burn treatments, with a high degree of species dominance exhibited by Anaplolepis steingroeveri. The ants seem to indicate higher species diversity in the burn treatment sites that had a more diverse vegetation structure. This occurrence however seems to alter over time after a fire incident, before returning to as close to its original state as possible. The beetles, however, displayed very haphazard assemblages, and did not show any discernable significant results that may be used to describe the environmental parameters in question.The reaction of the ants seemed to occur over an extended period of time, with immediate effects of the burn being an increase in non-specialised and opportunistic species abundances, possibly due to a decrease in competition with other species and taxa. Changes in ant assemblages became more apparent after seven years of the burn incident, seemingly linked to structural changes in the plant community. Ant species diversity increased again at the twelve year recovery time, with and associated change in plant habitat structure. The ants thus, in conclusion, show significant results towards indicating a response to habitat change brought on by fire. It is a requirement that this experiment be replicated in order to establish more discernable patterns. Additional recommendations to improve on this study are also discussed. / Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2009.

Master of Science / Food Science Institute / Randall K. Phebus / With the implementation of the Food and Drug Administration’s Food Safety Modernization Act, the food industry must scientifically verify that current production processes provide sufficient protection against pathogens. This study was conducted to validate a simulated commercial baking process for hamburger buns to control Salmonella spp. contamination and to determine the appropriateness of using non-pathogenic surrogates (Enterococcus faecium ATCC 8459 or Saccharomyces cerevisiae) for in-plant process validation studies. Wheat flour was separately inoculated (~6 log CFU/g) with three Salmonella serovars (Typhimurium, Newport or Senftenberg) or E. faecium. Dough was formed, proofed, and baked to mimic commercial manufacturing conditions. Non-inoculated dough was used to evaluate S. cerevisiae (Baker’s yeast) survival during baking. Buns were baked for 9, 11 and 13 min in a conventional oven set at 218°C, with internal bun temperature profiles recorded. Salmonella serovars and S. cerevisiae were reduced by >6 log[subscript]10 CFU/g after 9 min of baking. E. faecium was detected by direct plating after 11 min of baking but not after 13 min. After 13 min of baking, all three target organisms were eliminated (>6 log CFU/g reduction) in the buns. D- and z-values of Salmonella spp. (3-serovar cocktail), E. faecium, and S. cerevisiae in bun dough were also determined. D-values of Salmonella spp. and E. faecium during heating of dough were 28.64 and 133.33, 7.61 and 55.67, and 3.14 and 14.72 min at 55, 58 and 61°C, respectivly; whereas, D-values of S. cerevisiae were 18.73, 5.67 and 1.03 min at 52, 55 and 58°C, respectivly. The z-values of Salmonella spp., E. faecium and S. cerevisiae were 6.58, 6.25 and 4.74ºC, respectively. E. faecium demonstrated greater thermal resistance than Salmonella spp. and S. cerevisiae, making it an appropriate (and conservative) surrogate to establish thermal process lethality in the validation of commercial baking operations. The low thermal tolerance of S. cerevisiae relative to Salmonella limits its usefulness as a potential surrogate for process validations.

Pinnipeds exhibit a wide range of lactation strategies that vary from just a few days to nearly three years in duration. Phocids have a relatively short, intense nursing period culminating with weaning after just a few days or weeks, while dependent otariids generally take several months of consuming a combined milk and solid food diet before being completely independent. The transition to nutritional independence can be particularly challenging for newly weaned pups, which must adjust to behavioral, physiological and nutritional changes as a milk diet is replaced with solid food. An interruption in energy resources during this formative stage could result in a prioritization away from growth, maintenance, or activity resulting in suboptimal development. Three groups of ex situ California sea lion (Zalophus californianus) pups were examined during the initial period of independence after they were weaned at approximately five, seven, and nine months of age. Absolute growth rates of pups were calculated and changes in body composition were estimated using blubber depth measurements and deuterium oxide dilution to determine if weaning age had an effect on subsequent pup development and growth. Blood urea nitrogen and blood glucose levels were observed for their response to changes in body condition, while thyroid hormone levels in the blood were examined as a possible nutritional stress indicator during the pup's transition to solid food. When compared to in situ pups, the 5 month old pups in the present study had significantly greater body mass (39.6 ± 1.6 kg, p < 0.01), axillary girth (85.3 ± 2.9 cm, p < 0.01), and axillary blubber depth (2.3 ± 0.1 cm, p < 0.01) compared to 5 month old in situ pups (26.6 ± 5.2 kg / 70.6 ± 5.34 cm / 1.5 ± 0.2 cm). Nine month old ex situ pups had significantly greater axillary blubber depth (3.7 ± 0.9 cm, p < 0.01) and total body lipid percentage (24.9 ± 4.7%, p= 0.01) than in situ pups (1.5 ± 0.2 cm / 17.1 ± 4.9%). Although all pups in the present study survived the transition to solid food, there were apparent differences in how the different age groups responded physiologically. The five month old pups began the switch to solid food with the lowest overall blubber depth (2.6 ± 0.9 cm) and experienced the greatest change in body mass (-8.5 ± 1.6 kg) and composition while taking the longest to begin physiological recovery (31.7 ± 1.2 d). In contrast, the 9 month old pups entered the transition with more energy reserves (24.9 ± 4.7% TBL), began consuming solid food sooner (16.3 ± 0.6 d), and were able to utilize reserves more efficiently to minimize loss and promote faster growth.