Objetivo: Comparar in vitro la microdureza superficial del esmalte de dientes de bovino al ser expuestos a tres suplementos a base de caseína, creatina y leucina. Materiales y Métodos: Estudio de tipo experimental in vitro. Se evaluó la microdureza superficial inicial y final de 30 especímenes de esmalte bovino al ser expuestos a tres suplementos a base caseína, creatina y leucina. Se midió la microdureza superficial con un microdurómetro (Hv1000 LG - Corea del Sur) en los especímenes bovinos antes y después de la exposición. Dichos especímenes fueron almacenados a temperatura ambiente entre cada exposición. El análisis bivariado fue evaluado mediante la prueba de Wilcoxon para comparar la microdureza inicial y final de cada grupo y se utilizó la prueba de Kruskal Wallis para comparar la diferencia de microdureza en los diferentes tiempos y entre los suplementos. Además, se realizó la prueba de Dunn para verificar si existían similitudes entre los grupos analizados. El nivel de significancia se estableció como p<0.05. Resultados: El porcentaje de pérdida de la microdureza superficial con cada suplemento fue: caseína 2.63%, creatina 4.69% y leucina con 27.95% observándose diferencias estadísticamente significativas (p= 0.005) solo entre los grupos de creatina y leucina. Además, se encontraron diferencias estadísticamente significativas al comparar la diferencia de microdureza superficial inicial y final de los especímenes al ser expuestos a los tres suplementos. Conclusiones: En el presente estudio se observó que, la microdureza del esmalte bovino se ve reducida al ser expuesto a suplementos a base de caseína, leucina y creatina. Asimismo, se hallaron diferencias estadísticamente significativas en las pruebas realizadas las cuales concluyeron que la mayor pérdida en la microdureza superficial fueron en los especímenes expuestos al suplemento a base de leucina. / Objective: Compare in vitro the superficial microhardness of bovine tooth enamel when exposed to three supplements based on casein, creatine, and leucine. Materials and Methods: Experimental in vitro study. The initial and final surface microhardness of 30 bovine enamel specimens was evaluated when exposed to three supplements based on casein, creatine, and leucine. Surface microhardness was measured with a micro durometer (Hv1000 LG - South Korea) in the bovine specimens before and after challenge. Bivariate analysis was evaluated using the Wilcoxon test to compare the initial and final microhardness of each group and the Kruskal Wallis test was used to compare the difference in microhardness at different times and between the protein supplements. In addition, Dunn's test was performed to verify if there were similarities between the groups analyzed. The significance level was established as p <0.05. Results: The percentage of loss of surface microhardness with each supplement was: casein 2.63%, creatine 4.69% and leucine with 27.95%, observing statistically significant differences (p = 0.005) only between the creatine and leucine groups. In addition, statistically significant differences were found when comparing the initial and final surface microhardness difference of the specimens when exposed to the three supplements. Conclusions: In the present study it was observed that the microhardness of bovine enamel is reduced when exposed to supplements based on casein, leucine, and creatine. Likewise, statistically significant differences were found in the tests carried out which concluded that the greatest loss in surface microhardness was in the specimens exposed to the leucine-based supplement. / Tesis

<p>Dietary supplement (DS) use is highly prevalent in the U.S. and can contribute substantial amounts of micronutrients to the one-half of U.S. adults and nearly one-third of U.S. children who use them. Despite their pervasive use, the best practices for assessing the prevalence of use of and measuring nutrient intakes from supplemental sources remain largely unknown, and currently no metric designed to assess total micronutrient exposures from foods, beverages, and DS exists. Comprehensive and robust methods for assessing the prevalence of use of and nutrient intakes from DS are critical for population-level research and surveillance. </p> <p>Therefore, the overarching aims of the research presented in this dissertation were to 1) identify the most comprehensive method for assessing the prevalence of use of and estimating nutrient intakes from DS, 2) characterize DS use and examine trends in overall and micronutrient-containing DS use among the U.S. population using multiple modes of DS assessment, 3) develop the first micronutrient-based diet quality index designed to capture usual intakes from all sources of under-consumed micronutrients among the U.S. population (i.e., the Total Nutrient Index (TNI)) and 4) to determine if the TNI is a useful measure for assessing total micronutrient exposures among the U.S. adult population.</p> <p>National Health and Nutrition Examination Survey (NHANES) 2011-2014 data among U.S. adults were employed to evaluate four combinations of methods constructed from two data collection instruments (i.e., the 24-hour dietary recall (24HR) and the NHANES in-home inventory with a frequency-based DS prescription medicine questionnaire (DSMQ)) for measuring the prevalence of use of and amounts of selected nutrients from DS. The results from the analysis indicated that a higher prevalence of DS use is reported when using frequency-based methods, like the DSMQ, but higher nutrient amounts are reported on the 24HR. Thus, combining the DSMQ with at least one 24HR (i.e., DSMQ or ≥1 24HR) provides the most comprehensive approach for measuring DS use and estimating nutrient intakes from supplemental sources among U.S. adults.</p> <p>Differences in the estimated prevalence of use of DS on the DSMQ or ≥1 24HR as compared with the DSMQ only were also noted among a nationally representative sample of the U.S. population from the 2007-2018 NHANES. When characterizing DS use and examining trends in overall and micronutrient-containing DS use among the U.S. population using multiple modes of DS assessment, increases in both overall and micronutrient-containing DS use were observed over time, but the prevalence of use was lower on the DSMQ than the DSMQ or ≥1 24HR among the total population and across all population subgroups. Therefore, the findings from this study were congruent with our previous analysis and contributed to a growing body of literature that utilizes multiple methods of DS assessment to improve the comprehensiveness of DS exposure assessment. </p> <p>The insights garnered from identifying the most comprehensive method for approximating micronutrient intakes from supplemental sources were implemented in the development and initial application of the first micronutrient-based diet quality index designed to capture usual intakes from all sources of under-consumed micronutrients among the U.S. population, named the TNI. The TNI assesses U.S. adults’ total nutrient intakes relative to the Recommended Dietary Allowance or Adequate Intake for eight under-consumed micronutrients identified by the Dietary Guidelines for Americans: calcium, magnesium, potassium, choline, and vitamins A, C, D, E. In the initial application of the TNI, based on dietary data from the 2011-2014 NHANES, the mean TNI score of U.S. adults was 75.4 out of 100, whereas the mean score when ignoring contributions from DS was only 69.0 (t-test; p<0.001). Therefore, the results from this analysis suggested that the TNI extends existing measures of diet quality by including nutrient intakes from all sources.</p> <p>However, another analysis designed to examine the construct and criterion validity of the TNI was completed using data from a nationally representative sample of U.S. adults who participated in the 2011-2014 NHANES, as well as exemplary menus reflective of high-quality diets. The results showed that the TNI yielded high scores on exemplary menus (84.8-93.3 out of 100), was moderately correlated with the Healthy Eating Index-2015 (r=0.48) and was able to differentiate between groups with known differences in nutrient intake for DS users vs. non-DS users, non-smokers vs. smokers, and those who were food-secure vs. food insecure (all <em>p</em><0.001). Moreover, correlations of TNI component scores with nutritional biomarkers for vitamins A, C, D, and E were significantly higher when compared with those obtained via the diet alone.</p> <p>Taken together, the research findings from the studies presented in this dissertation contribute evidence supporting the use of multiple modes of DS assessment to improve the comprehensiveness of DS exposure assessment, as well as the importance of capturing micronutrient exposures from all sources. These results also highlight the broad applicability of the TNI framework as a tool for comprehensively representing the totality of nutrient exposures, inclusive of DS. Our outcomes point towards a need for additional investigation into the random and systematic error that pervades DS assessment, the development of tools that can be used to describe micronutrient exposures more completely and how those relate to nutritional status, as well as further applications of the TNI. </p>

(M.Sc. (Animal Production)) -- University of Limpopo, 2014 / Two experiments were conducted to determine the effect of dietary threonine level on productivity and carcass characteristics of indigenous Venda chickens. In each experiment the diets were isocaloric and isonitrogenous but with different dietary threonine levels. A complete randomized design was used in both experiments, the starter (1-7 weeks old unsexed chickens) and finisher (8-13 weeks old female chickens) experiments. The treatments were CT4 (4 g of threonine/kg DM), CT5 (5 g of threonine/kg DM), CT6 (6 g of threonine/kg DM), CT7 (7 g of threonine/kg DM) and CT8 (8 g of threonine/kg DM). A quadratic type of equation was used to determine dietary threonine levels for optimal feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy intake and nitrogen retention of unsexed Venda chickens aged one to seven weeks. Dietary threonine level affected (P<0.05) feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy and nitrogen retention. However, feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy and nitrogen retention of indigenous Venda chickens were optimized at different dietary threonine levels of 6.218, 6.437, 6.331, 6.655, 5.979 and 6.158 g/kg DM feed, respectively. Dietary threonine level did not affect (P>0.05) mortality rate of the chickens. The treatments for the second experiment were FT4 (4 g of threonine/kg DM), FT5 (5 g of threonine/kg DM), FT6 (6 g of threonine/kg DM), FT7 (7 g of threonine/kg DM) and FT8 (8 g of threonine/kg DM). Dietary threonine level had effect (P<0.05) on feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy and nitrogen retention of female Venda chickens aged eight to 13 weeks. Feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy intake and nitrogen retention of chickens were optimized at dietary threonine levels of 6.054, 6.142, 6.442, 6.201, 5.72 and 6.088 g/kg DM, respectively. However, dietary threonine level had no effect (P>0.05) on pH values of crop, proventriculus, gizzard, small intestine, large intestine and caecum of female Venda chickens aged 91 days. Carcass weights of female Venda chickens were affected (P<0.05) by dietary threonine level. Carcass, breast, drumstick, thigh, gizzard and liver weights of female Venda chickens aged 91 days were optimized at dietary threonine levels of 6.183, 6.201, 5.712, 5.847, 4.820 and 6.180 g/kg DM, respectively. Dietary threonine level v had effect (P<0.05) on crude protein and threonine contents of female Venda chicken meat. Meat crude protein and threonine contents of female Venda chickens aged 91 days were optimized at dietary threonine levels of 5.9 and 5.7 g/kg DM, respectively. Dietary threonine level had no effect (P>0.05) on meat flavour, tenderness and juiciness of female Venda chickens. However, meat flavour, tenderness and juiciness of female Venda chickens aged 91 days were optimized at dietary threonine levels of 5.977, 6.103 and 5.977 g/kg DM, respectively. No chicken deaths were observed. / National Research Foundation (NRF)

Thesis (M.Sc. (Animal Production)) -- University of Limpopo, 2023 / The development curve of Venda chicken fed with various amounts of citric acid was evaluated using nonlinear models in an experiment. to ascertain the effects of citric acid supplementation level on feed intake, body weight increase, and linear measurements on Venda chickens. 200 male Venda chickens were used in the experiment which lasted 90 days. The chicks were randomly assigned to four treatments (0, 12.5, 25 and 50g of citric acid inclusion) with 5 replications, resulting in 20 floor pens with 10 chicks per replicate. A completely randomized design was employed as experimental design. Analysis of Variance (ANOVA) was used to determine the effect of citric acid on feed intake, body weight gain, FCR, GR and body linear measurements. Three different non-linear models, namely Gompertz, Weibull, and Richards, were used to define the growth curves of the Venda chickens. The Duncan multiple range test at the 5% level of significance was utilized to detect significant differences between the means. Models were compared using coefficients of determination (R2) and standard errors (SE). The results indicated that feed intake, body weight, average daily gain and growth rate of Venda chickens were not affected (p > 0.05) by citric acid supplementation levels. Similarly, Citric acid supplementation had no effects (p > 0.05) on the shank length and wing length of Venda chickens. However, feed conversion ratio (FCR) of Venda chickens was improved (p < 0.05) by with an increase in citric acid supplementation. The Venda chicken fed citric acid at grower phase and finisher phase had better growth performances than the starter phase. Citric acid supplementation improved the back length and thigh length of Venda chickens. The Venda chickens fed citric acid at 25g inclusion level significantly higher back and thigh length. The coefficient of determination ranged from 0.00 to 0.98 in all the treatments. The Gompertz Model and Richards Models both exhibited the same coefficient of determination across all treatments. The model with the lowest standard error was found to best describe the growth curve of male Venda across all treatments. The Gompertz model was observed to be suitable for explaining the growth of Venda chickens fed with feed without citric acid (CA0g) and citric acid 125g inclusion (CA12.5g). The Richards model was observed to be suitable for explaining the growth of Venda chickens fed citric acid 25g inclusion (CA25g) and citric acid 50g inclusion (CA50g). It is recommended to use a supplement containing lower citric acid to enhance the body linear measurements and growth performance of the chickens. Gompertz and Richards models can be utilized to characterize the growth curve of Venda chickens. / National Research Foundation (NRF)

No description available.

Thesis (M. Tech. Agriculture) -- Central University of Technology, Free state, 2012 / The eight-week study was conducted to evaluate the effects of rearing system (indoor vs. outdoor) and energy level on digestibility, growth performance and on the carcass characteristics and visceral organs of pigs. A total of 48 Large Whites (LW) X Landrace (LR) male grower pigs were randomly selected at average weights of 27 ± 4.6.kg and divided into two equal groups that were either raised indoors or outdoors. Within each rearing system, half the pigs were fed on a diet formulated to contain either a normal energy level (14 MJ DE/kg) or high energy level (16.1 MJ DE/kg) resulting in a 2 X 2 factorial design. The pigs were fed ad libitum and water was freely available. Pigs were housed in pairs and each indoor and outdoor pig was offered a space allowance of 0.51 and 13.5 m2 respectively. Indoor pigs were raised in a temperature controlled house consisting of a concrete floor pen while outdoor pigs were on a pasture that predominantly consisted of Kikuyu. Movable gates were used to construct outdoor camps and empty feed bags were used to construct a shade for use as shelter. Faecal collection for digestibility determination took place during week 7 while the growth performance trial was still in progress. Chromium oxide was used to evaluate digestibility and faeces were grabbed before they fell to the ground and sampled. With the exception of ether extracts (EE), the digestibilities of crude protein (CP), digestible energy (DE), crude fibre (CF), neutral detergent fibre (NDF), acid detergent fibre (ADF) and organic matter (OM) were reduced (P <0.05) by rearing pigs outdoors. EE followed the same trend. Feeding the high energy (HE) diet significantly (P >0.05) improved the digestibilities of all the nutrients except for CP. There were no significant interactions (P>0.05) between rearing system and diet for the digestibility of nutrients. Daily gains were similar (P >0.05) between indoor and outdoor pigs. Daily feed intakes and conversions were significantly (P <0.05) lower in indoor pigs. There were no significant (P >0.05) differences between the daily gains and feed conversions of pigs fed either the normal energy (NE) or the HE diet. Indoor pigs fed the HE diet had lower (P < 0.05) feed intakes compared to pigs on the other treatments. In general, average daily feed intakes (ADFI) of the HE fed pigs were significantly (P <0.05) lower than those of the NE fed pigs. The carcass measurements of the indoor and outdoor pigs were similar. The gastro-intestinal tract (GIT) and the liver weights of the outdoor reared pigs were significantly (P <0.05) heavier than those of the indoor reared pigs. Feeding the HE diet led to significantly (P <0.05) higher carcass weights and dressing percentages. Interactive effects (P <0.05) of diet and rearing system were found for lean meat percentage (Lean P) and eye muscle area (EMA). Indoor pigs fed on the NE diet had higher Lean P and EMA while an opposite effect was obtained in the outdoor system. The liver of the NE diet fed pigs was significantly (P < 0.05) heavier than that of the pigs fed the HE diet. It can be concluded that with regard to growth performance and carcass characteristics, the NE and HE diets are respectively best suited for the indoor and outdoor rearing of pigs.

Thesis (M.Tech.: Homoeopathy)-Dept. of Homoeopathy, Durban Institute of Technology, 2006 xxv, 261 leaves / The aim of the study was to evaluate the efficacy of a Nutritional Supplement (Advanced Brain Food®) and a homoeopathic complex (Quietude®) in the management of Attention Deficit Hyperactivity Disorder (ADHD). ADHD is primarily a childhood disorder affecting ten to twenty percent of school going children. The three main presenting features of ADHD are inattention, impulsivity, and hyperactivity. This triad often results in numerous adjustment difficulties for the child in the social and academic sectors (NIH Consensus Statement, 1998).

Submitted in fulfillment of the requirements of the degree of Doctor of Technology: Health Sciences, Durban University of Technology, Durban, South Africa, 2015. / Background: In a vulnerable low-income group with a confirmed high risk of cardiovascular disease, like the elderly in the Sharpeville care centre, an acute intervention is needed in order to improve their health profile. Previous studies suggested homocysteine lowering by vitamin B12, B6 and folate supplementation. The effect of vitamin B12, B6 and folate supplementation on the inflammatory response, thrombotic risk, lipid profile, hypertension, risk of metabolic syndrome and homocysteine metabolism in an elderly, black South African population has never been reported. Objectives: The main aim of this interventional study was to assess the effect of vitamins B12, B6 and folate supplementation at 200% RDA for six months on cardiovascular risk markers of an elderly semi-urbanised black South African community. Design: This study was an experimental intervention non-equivalent control group study design in 104 purposively selected samples of all the elderly attending the day-care centre. Setting and participants: A homogeneous group of respondents was included in the study. All subjects were equivalent in age (>60 years), race (black), unemployed/pensioners (socio-demographic) and 60 years and older attending a day care centre in Sharpeville, situated in the Vaal region, Gauteng, SA. Measurements: The distinctiveness of this study lies in the broad panel of parameters evaluating the CVR in correlation with the increased nutritional intake of vitamin B6, B12 and folate. These included: weight, height, waist, serum cholesterol, high density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides, blood pressure, fibrinogen, high-sensitivity C-reactive protein (HS–CRP), homocysteine, vitamin B12, folate, glucose, insulin, adiponectin and fibronectin. Results: A very high incidence (66.36%) of hyperhomocysteinaemia is present in the sample. The mean serum homocysteine level in hyperhomocysteinaemic individuals decreased statistically significantly from 25.00±8.00 umol/l to 18.80±12.00 umol/l after the intervention. The number of respondents with an increased homocysteine level decreased from 100% (baseline) to 67% (follow-up). The supplementation was beneficial (statistically significant changes) to the glucose levels, fibrinolytic status, vitamin B6 serum levels, fibronectin levels and haemopoeiesis (decreased macrocytosis) of all the individuals (regardless of their homocysteine status). Conclusion: It is concluded that supplementation of vitamins B6, B12 and folate at 200% RDA for six months is an effective homocysteine-lowering approach as a strategy to reduce hyperhomocysteinaemia in an elderly population and thereby reduce cardiovascular risk (CVR). The supplementation intervention mentioned is not an effective multifactorial strategy to decrease CVR although beneficial effects were found with other CVR markers independent of homocysteine status.

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Human studies on the response of muscle to contusion injury are limited, probably due to the large variability in injury severity and the non-specificity of clinical symptoms reported. To circumvent this problem, several experimental animal models have been designed to study muscle damage and regeneration after contusion injuries. However, the majority of techniques currently used to induce contusion injury are very invasive and therefore not optimal. Furthermore, published studies regarding clinical treatment of such injuries are limited. The main aims of this study were therefore: a) to establish and characterise an in vivo model of non-invasive contusion injury, and b) to assess the effect of pre-injury chronic administration of the antioxidant supplement Oxiprovin™ - a natural grape seed extract (GSE) - on skeletal muscle recovery after experimentallyinduced injury. Two groups of male Wistar rats were subjected to 14 days of oral administration of isovolaemic placebo (sterile isotonic saline) or GSE (20 mg/kg/day) prior to induced contusion. Contusion injury was induced with the mass-drop technique, and recovery parameters assessed for up to 14 days post-injury. Placebotreated rats on average exhibited a 56 % higher creatine kinase (CK) activity when compared to the GSE-treated rats when area under the curve (AUC) was calculated for 14 days post-injury (p < 0.001). In the placebo group, plasma oxygen radical absorbance capacity (ORAC) was unchanged over time, but muscle ORAC was significantly increased by day 7 post-injury (p < 0.001). In the GSE group, a significant decrease in both plasma (p < 0.01) and muscle ORAC (p < 0.001) was evident 4 hr after injury, followed by a significant increase by day 3 (p < 0.05 and p < 0.001 respectively). CD34+ satellite cell (SC) numbers (quiescent and activated) peaked earlier in GSE-treated rats when compared to placebo-treated rats (4 hours vs. day 7 post-injury). Total satellite cell number (CD56+) also peaked earlier in GSE-treated rats than in placebo-treated rats (4 hours vs. 3 days post-injury), while M-cadherin+ SC numbers (quiescent, activated or proliferating) in both treatment groups were significantly increased 4 hours post-injury (p < 0.001), but more so in the placebo group. In GSE-treated rats when compared to placebo-treated rats, newly generated muscle fibres (displaying central nuclei and MHCf +) both appeared (day 3 vs. day 7 post-injury) and peaked in number (day 3 vs. day 7 post-injury; increase from baseline p < 0.001 for both) earlier. The results of this study demonstrate that we have successfully established an in vivo model for non-invasive contusion injury in rats. Furthermore, we have shown that Oxiprovin™: a) increased the ability to scavenge reactive species generated after injury and b) resulted in the activation of satellite cells and formation of newly generated muscle fibres at an earlier time point, thus accelerating the recovery of skeletal muscle after a standardised contusion injury. / AFRIKAANSE OPSOMMING: Eksperimente aangaande die reaksie van spier op kneusings in mense is beperk, waarskynlik as gevolg van die groot verskeidenheid simptome wat mag voorkom en die verskille in die ernstigheid van beserings. Ten einde hierdie problem te oorbrug, is verskeie eksperimentele diermodelle opgestel om kneusings en die herstel van spier daarna te ondersoek. Die tegnieke wat grootendeels vandag gebruik word om kneusings te veroorsaak, maak inbraak op die spier deur die spier te ontbloot voor besering, en is dus nie ideaal nie. Daar is ook nie baie bewyse aangaande die mees geskikte manier om so ‘n besering klinies te behandel nie. Die doel van hierdie studie was dus om: a) ‘n in vivo model van kneusings op te stel en te omskryf, en b) die effek van chroniese toediening van die antioksidant Oxiprovin™ - ‘n natuurlike druifsaad ekstrak (DSE) – op die herstel van skeletspier na ‘n kneusing te ondersoek. Twee groepe manlike Wistar rotte is onderwerp aan mondelikse toediening van isovolemiese plasebo (steriele isotoniese soutoplossing) of DSE (20 mg/kg/dag) vir ‘n tydperk van 14 dae voor kneusing. Kneusing is geïnduseer met die “massdrop” tegniek, en parameters van herstel is ondersoek tot en met 14 dae na besering. Plasebo-behandelde rotte het gemiddeld 56 % hoër kreatien kinase (KK) aktiwiteit in vergelyking met DSE-behandelde rotte (p < 0.001), toe die oppervlak onder die kurwe (OOK) tot en met 14 dae na besering bereken is. Geen verskil oor tyd is in die plasebo groep opgemerk toe plasma suurstof radikaal absorpsie kapasiteit (SRAK) bepaal is nie, maar ‘n betekenisvolle toename in spier SRAK teen dag 7 (p < 0.001) is waargeneem. ‘n Betekenisvolle afname in beide plasma (p < 0.01) en spier (p < 0.001) SRAK van die DSE is teen 4 hr waargeneem, gevolg deur ‘n betekenisvolle toename teen dag 3 na besering (p < 0.05 en p < 0.001 onderskeidelik). Die aantal CD34+ satelliet selle (SS – rustend en geaktiveerd) het beduidend vroeër in die DSE groep gestyg in vergelyking met die plasebo groep (4 uur vs. 7 dae na besering). Die totale aantal SS (CD56+) het ook vroeër in die DSE-behandelde rotte as die plasebobehandelde rotte gestyg (4 uur vs. 3 dae na besering), terwyl die aantal Mcadherin+ SS (rustend, geaktiveerd of prolifererend) betenisvol gestyg het in beide groepe teen 4 uur (p < 0.001) na besering, maar hoër in die plasebo groep was. Die aantal nuutgevormde spiervesels (met sentraal geleë nukleï en MHCf +) het beide vroeër verskyn en gepiek in die DSE-behandelde rotte in vergelyking met die plasebo-behandelde rotte (dag 3 vs. dag 7 na besering). Die resultate van hierdie studie dui aan dat ons instaat was om ‘n in vivo model van nie-indringende kneusing in rotte op te stel. Verder, het ons ook bewys dat Oxiprovin™ toediening die vermoë verleen het om: a) reaktiewe spesies wat na beserings gevorm word, meer doeltreffend te verwyder en b) satelliet selle vroeër te aktiveer en die vorming van nuwe skeletspiervesels te vervroeg, om sodoende die herstel van skeletspier na ‘n gestandardiseerde kneusing vinniger te bewerkstellig.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Kikuyu over-sown with ryegrass forms the basis of pasture based systems in the Southern Cape. During early spring, energy is the first limiting nutrient in kikuyu/ryegrass pasture, supplementation is thus essential. Supplementation consists mainly of high starch concentrates (high maize inclusion), which is expensive and could negatively affect rumen parameters. The objective of this study was to determine if milk production could be improved or maintained, and if the rumen environment would be improved, by replacing high starch concentrates with low starch (high by-product) concentrates for dairy cows on kikuyu/ryegrass pasture. Forty-five multiparous, high producing, lactating Jersey cows [body weight, 340 ± 34.7 kg; milk yield (MY), 19.6 ± 2.23kg/d; days in milk (DIM), 153 ± 33.5; lactation number, 3.6 ± 1.85; (mean ± SD)] were used in the production study. A randomised block design was used. The forty-five cows were allocated to fifteen groups of three each (blocking) on the basis of MY, DIM, and lactation number. Cows from each group were randomly allocated to one of three treatment groups (high starch, medium starch and low starch concentrate supplementation). Cows were fed 6kg (3kg during each milking) concentrate per day and were allocated fresh pasture ad lib after each milking. There were no significant differences (P > 0.05) found in milk yield and fat corrected milk yield between treatment groups. Milk fat percentage was significantly higher (P < 0.05) in the low starch treatment than in the high starch treatment. Milk fat yield was significantly higher (P < 0.05) in both the low starch and the medium starch treatment when compared to the high starch treatment. Milk protein and lactose percentages, as well as milk urea nitrogen and somatic cell count, did not differ significantly (P > 0.05) between treatments. Live weight change, as well as body condition score change, was unaffected (P > 0.05) by treatments indicating body reserves were not used to maintain milk production in the low starch treatment. A rumen metabolism study was also done with ten lactating, cannulated Jersey cows [body weight, 332 ± 56.3 kg; MY, 17.3 ± 1.73kg/d (mean ± SD)] were used. The cows were divided into two groups of five each, on the basis of lactation number, DIM, and MY. The five cows from each group were randomly allocated to one of two treatment groups (high starch and low starch concentrate supplementation) and used in a cross-over design. Cows were fed 6kg concentrate per day and were allocated fresh pasture ad lib after each milking. The volatile fatty acid (VFA) concentration was significantly higher (P < 0.05) in the high starch treatment when compared to the low starch treatment. The individual VFA’s, acetic-, propionic- and butyric acid concentrations were also significantly higher (P < 0.05) in the high starch treatments when compared to the low starch treatment. The acetic to propionic acid ratio was unaffected (P > 0.05) by treatment. Rumen ammonia-nitrogen concentration was significantly higher (P < 0.05) in the high starch treatment. Rumen pH was unaffected (P > 0.05) by supplementation type. The in sacco dry matter and neutral detergent fibre digestibilities of the kikuyu/ryegrass pasture were unaffected (P > 0.05) by treatment type. Results indicated that milk production could be maintained with low starch concentrates which also improved milk composition. Results further suggested that the rumen environment was relatively unaffected by low starch concentrate supplementation. / AFRIKAANSE OPSOMMING: Kikoejoe, oorgesaai met raaigras, vorm die basis van weidingstelsels in the Suid-Kaap. Tydens die lentemaande is energie die eerste beperkende voedingstof op kikoejoe/raaigras weidings, wat kragvoeraanvulling noodsaaklik maak. Aanvulling bestaan grootliks uit hoëstysel-kragvoer (hoë mielieinhoud) wat nie net duur is nie, maar dit kan ook die rumenomgewing benadeel. Die doel van die studie was om vas te stel of melkproduksievlakke onderhou kan word en of rumenomgewing verbeter kan word deur die vervanging van hoëstysel-kragvoer met laestysel-kragvoer (hoë neweprodukinhoud) vir melkkoeie op kikoejoe/raaigras weidingstelsels. Vyf-en-veertig meervoudige pariteit-, hoë produserende, lakterende Jerseykoeie [liggaamsmassa, 340 ± 34.7 kg; melkproduksie, 19.6 ± 2.23kg/d; dae in melk, 153 ± 33.5; laktasienommer, 3.6 ± 1.85; (gem ± standaardafwyking)] is gebruik vir die produksiestudie van die proef. Daar is gebruik gemaak van ‘n ewekansige blokontwerp. Die vyf-en-veertig koeie is opgedeel in vyftien groepe van drie elk, gebaseer op melkproduksie, dae in melk en laktasienommer. Koeie in elke groep is ewekansig aan een van drie behandelings (hoëstysel-, mediumstysel- of laestysel-kragvoeraanvulling) geallokeer. Koeie is daagliks 6kg (3kg tydens twee milkings) kragvoer gevoer en vars weiding was ad lib beskikbaar na elke melking. Daar was geen beduidende verskil (P > 0.05) in melkopbrengs of vet-gekorrigeerde melkopbrengs tussen die drie behandelings nie. Bottervetpersentasie was beduidend hoër (P < 0.05) in die laestyselbehandeling in vergelyking met die hoëstyselbehandeling. Bottervetopbrengs was beduidend hoër (P < 0.05) in beide die laestysel- en mediumstyselbehandelings in vergelyking met die hoëstyselbehandeling. Melkproteïen- en melklaktosepersentasies, asook melkureumstikstof en somatise seltelling, was onveranderd (P > 0.05) tussen behandelinge. Liggaamsmassa en liggaamskondisietelling het geen verskille (P > 0.05) getoon tussen behandelings nie, wat daarop dui dat liggaamsreserwes nie gebruik is om melkproduksie in die laestyselbehandeling te onderhou nie. ‘n Rumenmetabolismestudie is ook uitgevoer met tien lakterende, gekannuleerde Jerseykoeie [liggaamsmassa, 332 ± 56.3 kg; melkproduksie, 17.3 ± 1.73kg/d (gem ± standard afwyking)]. Die koeie is in twee groepe van vyf elk verdeel, gebasseer op laktasienommer, dae in melk en melkproduksie. Die vyf koeie van elke groep is in ‘n omslagontwerp gebruik en is ewekansig aan een van twee behandelings (hoëstysel- of laestysel-kragvoeraanvulling) geallokeer. Koeie het daagliks 6kg kragvoer ontvang en vars weiding was ad lib beskikbaar na elke melking. Die vlugtige vetsuurkonsentrasie was beduidend hoër (P < 0.05) in die hoëstyselbehandeling as in die laestyselbehandeling. Die individuele vlugtige vetsure naamlik asynsuur, propionsuur en bottersuur, was ook beduidend hoër (P < 0.05) in die hoëstyselbehandeling as in die laestyselbehandeling. Die asynsuur- tot propionsuurverhoudings het geen verskille (P > 0.05) tussen behandelings getoon nie. Rumen-ammoniakstikstof was beduidend hoër (P < 0.05) in die hoëstyselbehandeling as in die laestyselbehandeling. Rumen-pH het geen verskille (P > 0.05) getoon tussen behandelings nie. Die in sacco droëmateriaal- en neutraalbestande veselverteerbaarhede van kikoejoe/raaigras weiding het geen verskille (P > 0.05) tussen behandelings getoon nie. Die resultate het aangedui dat melkproduksie onderhou kan word en dat melksamestelling verbeter kan word met laestysel-kragvoeraanvulling. Resultate het ook daarop gedui dat die rumenomgewing nie noodwendig verbeter word deur die aanvulling van laestysel-kragvoer vir koeie op kikoejoe/raaigras weidings nie.