The effect of feed processing and nutrient density level on the growth rate, feed conversion, rumen fermentation parameters and economy of finishing lambs

Thesis (MScAgric)--Stellenbosch University, 2022.ENGLISH ABSTRACT: The primary objective of this study was to investigate the influence of feed processing on lamb performance, feedlot profitability and rumen fermentation parameters and the interaction of feed pelleting effects with nutrient density in the diet. In the first trial a total of 64 S.A. Mutton Merino male lambs were randomly allocated to 8 pens. The pens were randomly assigned to 2 treatment blocks of either high nutrient density (HD) or low nutrient density (LD). Within each treatment block, the control group was offered a total mixed ration (TMR) containing coarse grain, protein, additives and chopped roughage (Groups L0 and H0). Three treatment groups within each block were offered a complete pelleted ration (CPR) with pellet sizes of 4mm (L4 and H4), 6mm (L6 and H6) and 8mm (L8 and H8) diameter. Over an experimental period of 7 to 8 weeks, the dry matter intake (DMI), average daily gain (ADG), feed efficiency (FCR) and feedlot economy were measured for the different groups. The average DMI of the H4 group was significantly (P < 0.05) lower than the average DMI of all the other groups except for the L0 group. The ADG of lambs that received the L0 diet was significantly lower (P < 0.05) than the ADG of all the other groups. The lambs receiving the H6 diet achieved the highest ADG (0.305 kg/d ± 0.04). The ADG of the H6 group was significantly higher (P < 0.05) than the ADG of lambs on the H4 diet. Pelleting increased ADG in the low- density diets by an average of 44% (195g/d versus 281g/d; P < 0.01), while no significant ADG response of pelleting was observed in lambs fed the high-density diets. The least effective feed conversion rate (FCR) was achieved by the L0 group (6.9 kg ± 0.90), which also differed significantly (P < 0.05) from all the other groups. Although not significant, the FCR of the high- density groups was numerically better than the FCR of the low-density groups. Within the LD and the HD groups, a tendency (P < 0.10) towards a better FCR with an increase in pellet size were established. The average dressing percentage (DP) of the lambs that received HD diets were significantly (P < 0.05) higher than the lambs on LD diets. The highest average gross profit (GP) was obtained by the H8 (R310/lamb) and the H0 (R283/lamb) groups and differed significantly (P < 0.05). At an average of R76/lamb, the L0 group returned the lowest GP of all the groups. The pelleting of the complete LD diet improves growth and economic performance of fattening lambs mainly due to an increase (P < 0.05) in DMI and a better FCR, while pelleting of a complete HD diet did not show any effect on lamb performance. The use of larger diameter pellets in a HD diet seems to be more beneficial to lamb performance than the use of smaller pellets. The aim of the second study was to evaluate the effects of feed pelleting and feed nutrient density on the rumen fermentation parameters of sheep. A total of 8 mature S.A. Mutton Merino ewes were used in a change-over design with a repeated observation experiment. The main treatment blocks were either high nutrient density (HD) or low nutrient density (LD) rations. Within each treatment block, the control group was offered a total mixed ration (TMR) containing coarse grain, protein, additives and chopped roughage (Groups L0 and H0). Three treatment groups within each block were offered a complete pelleted ration (CPR) with pellet sizes of 4mm (L4 and H4), 6mm (L6 and H6) and 8mm (L8 and H8) diameter. The animals fed the LD diets resulted in significantly (P < 0.05) higher daily dry matter intake (DMI) compared to the HD diets. The average ruminal pH of the sheep dropped to a minimum at approximately 4 hours after feeding, after which the pH slowly returned to the initial values. The sheep that received both the L8 and L6 diets had the lowest average ruminal pH reading at 4 hours after feeding, while group H0 had the lowest reduction in ruminal pH (P < 0.01). The ruminal pH of sheep on all three of the LD pelleted diets, experienced a lower ruminal pH for a longer time after the meals than what was observed in the HD pelleted rations and was attributed to higher DMI. Sheep that was fed unprocessed feeds (H0 and L0), had a less significant drop and a slower recovery rate to the initial ruminal pH compared to the sheep on processed feeds. Concentrations of volatile fatty acids were higher in the LD groups than in the HD groups. Rumen ammonia nitrogen (RAN) measurements and methylene blue reduction (MBR) test results did not indicate to any association between nutrient density and level of processing of the diet. The faecal pH of the sheep at 6 hours after feeding followed the general trend of the ruminal pH findings, but no definite association with either feed nutrient density or level of processing could be established. The same was observed with the MBR test on the ruminal fluid at 6 hours after feeding. The observed differences in rumen fermentation parameters in sheep on high and low nutrient density diets, could be explained by higher DMI as well as rate of starch intake.AFRIKAANSE OPSOMMING: Die primêre doel van hierdie studie was om die invloed van voerprosessering deur verpilling en voerdigtheid op lamprestasie, voerkraalwinsgewendheid en rumenfermentasie parameters te ondersoek. In die eerste studie is 64 S.A. Vleis Merino ramlammers met 'n aanvangsmassa van 30-32 kg ewekansig aan 8 groepe toegeken. Die groepe is ook ewekansig aan twee behandelings blokke toegeken, naamlik ‘n hoë voedingsdigtheid (HD) voer en ‘n lae voedingsdigtheid (LD) voer. Binne elke behandelingsblok was die kontrolegroep 'n volledige rantsoen bestaande uit growwe graan, proteïen, bymiddels en gekerfde ruvoer (Groepe L0 en H0). Drie behandelingsgroepe binne elke blok het 'n volledige verpilde rantsoen ontvang met pil groottes van 4 mm (L4 en H4), 6 mm (L6 en H6) en 8 mm (L8 en H8). Gedurende die eksperimentele periode van 7 tot 8 weke is die droë materiaal inname (DMI), gemiddelde daaglikse toename (ADG), voeromsetdoeltreffendheid (FCR) en ekonomie vir die verskillende groepe gemeet. Betekenisvol hoër (P < 0.05) daaglikse DMI is waargeneem by diere wat LD diete teenoor HD diete gevoer is. Die gemiddelde DMI van die H4-groep was betekenisvol (P < 0.01) laer as die gemiddelde DMI van al die ander groepe, met die uitsondering van die L0- groep. Die ADG van lammers wat die L0-dieet ontvang het (0,195 kg/d ± 0,03) was aansienlik laer (P < 0.05) as die ADG van al die ander groepe. Die lammers wat die H6-dieet ontvang het, het die hoogste ADG behaal en was was aansienlik (P < 0.05) hoër as die ADG van die lammers op die H4-dieet. Verpilling het die ADG van die lammers wat die LD diete ontvang het, met gemiddeld 44% verhoog (195 g/d teenoor 281 g/d; P < 0,01), terwyl geen noemenswaardige ADG-respons weens verpilling by lammers op die HD diete waargeneem is nie. Die swakste voeromsetdoeltreffendheid (FCR) is deur die L0-groep (6,9 kg ± 0,90) behaal, wat ook betekenisvol (P < 0.05) verskil het van al die ander groepe. Alhoewel nie- betekenisvol, was die FCR van die groepe wat die HD dieet ontvang het, numeries beter as die FCR van die groepe wat die LD diete ontvang het. Binne die LD- en die HD-groepe was daar 'n neiging (P < 0.10) na 'n beter FCR met 'n toename in pil grootte. Die gemiddelde uitslag persentasie (DP) van die lammers wat HD-diëte ontvang het, was betekenisvol (P < 0.05) hoër as die lammers op LD-diëte. Die H8 (R310/lam) en H0 (R283/lam) groepe het die hoogste bruto marge (GP) van alle groepe gerealiseer en was ook aansienlik beter (P < 0.05) as die GP van al die LD-groepe. Die L0-groep het die laagste GP van al die groepe gerealiseer, met ‘n gemiddeld van R76/lam. Die beter GP van die HD-groepe was hoofsaaklik toegeskryf aan die beter karkas opbrengs. Die gevolgtrekking van die proef is dat verpilling van die LD-diete die groei en ekonomiese prestasie van lamafronddiete verbeter hoofsaaklik weens verhoogde DMI en 'n verbeterde FCR. Verpilling van 'n volledige HD-diete het nie 'n beduidende uitwerking op lamprestasie gelewer nie. Die gebruik van voerpille met ‘n groter deursnit in 'n HD-dieet is meer voordelig vir lamprestasie as die gebruik van kleiner pille. Die doel van die tweede studie was om die effek van voerverpilling en voerdigtheid op die rumen fermentasie parameters van skape te evalueer. Altesaam 8 volwasse S.A. Vleis Merino-ooie is gebruik in 'n omskakelontwerp met 'n herhaalde waarnemings eksperiment. Die belangrikste behandelingsblokke was of die hoë voerdigtheid (HD) of lae voerdigtheid (LD) diete. Binne elke behandelingsblok het die kontrolegroep 'n volledige dieet ontvang wat growwe graan, proteïen, bymiddels en gekerfde ruvoer bevat (Groepe L0 en H0) het. Drie behandelingsgroepe binne elke blok het 'n volledige verpilde dieet ontvang met 4 mm (L4 en H4), 6 mm (L6 en H6) en 8 mm (L8 en H8) deursnit respektiewelik. Die gemiddelde ruminale pH van die skape het ongeveer 4 uur na voeding tot 'n minimum gedaal, waarna die ruminale pH stadig na die aanvanklike waardes teruggekeer het. Die skape wat beide die L8- en L6- diete ontvang het, het die laagste gemiddelde pH-lesing op 4 uur na voeding gehad, terwyl H0 groep die laagste (P < 0 .05) daling in ruminale pH getoon het. Die ruminale pH van skape op al drie die LD-korrel-diete, het 'n laer pH vir 'n langer tyd na die maaltye getoon as wat in die HD-korrel-diete waargeneem is. Skape wat die ongeprosesseerde voere (H0 en L0) ontvang het, het 'n minder beduidende daling en 'n stadiger hersteltempo tot die aanvanklike ruminale pH ervaar as wat die geval met die skape wat die verpilde voer ontvang het was. Konsentrasies van vlugtige vetsure was hoër in die LD-groepe as in die HD-groepe. Rumen- ammoniak stikstof (RAN) metings en metileenblou reduksie (MBR) -toetsresultate het geen verband met voedingsdigtheid of die vlak van prosessering van die dieet getoon nie. Die fekale pH van die skape op 6 uur na voeding het ‘n soortgelyke tendens as die algemene neiging van die ruminale pH-bevindings getoon, maar daar kon geen definitiewe verband met voerdigtheid of vlak van prosessering bepaal word nie. Dieselfde is waargeneem met die MBR-toets op die ruminale vloeistof 6 uur na voeding. Die waargeneemde verskille in rumen fermentasie parameters by skape op hoë en lae voerdigthede, kan verklaar word deur hoër DMI en hoër tempos van styselinnames.Master

Identifying consumer buying preferences of beef

This study investigated the drivers which influence consumers’ beef buying behavior. A validated questionnaire was used to collect the data and to evaluate consumer beef purchasing behavior. Exploratory factor analysis was employed to analyze the data while Cronbach alpha coefficient was used to calculate the reliability of the drivers. Satisfactory levels of reliability were recorded. The analysis identified eight drivers that influence the buying behavior of consumers when they purchase beef products. These drivers were: quality of the meat, buying preference, farming practices, intention to buy, health, convenience, packaging &amp; presentation and future purchase. In addition, correlational analysis indicates that additional important attributes to buying behavior are supplier characteristics and packaging &amp; presentation. The study culminates in a frame of reference for beef (and possibly other meat products) buying behavior analysis whilst it also provides a frame of reference for marketers to better understand their customers’ behavior when they are selling beef. As a result it is recommended that retailers focus their actions on the more important beef purchasing drivers and that the study be repeated on a larger scale so that the results of the present study can either be confirmed or further refined. Keywords: beef cattle, buying behavior, consumer preferences of beef, packaging, farming practices, factor analysis. JEL Classification: M3

The ride comfort vs. handling compromise for off-road vehicles

When designing vehicle suspension systems, it is well-known that spring and damper characteristics required for good handling on a vehicle are not the same as those required for good ride comfort. Any choice of spring and damper characteristic is therefore necessarily a compromise between ride comfort and handling. The compromise is more pronounced on off-road vehicles, as they require good ride comfort over rough off-road terrain, as well as acceptable on-road handling. In this paper, the ride comfort vs. handling compromise for off-road vehicles is investigated by means of three case studies. All three case studies indicate that the spring and damper charcteristics required for ride comfort and handling lie on opposite extremes of the design space. Design criteria for a semi-active suspension system, that could significantly reduce, or even eliminate the ride comfort vs. handling compromise, are proposed. The system should be capable of switching safely and predictably between a stiff spring and high damping mode (for handling) as well as a soft spring and low damping mode (for ride comfort). A possible solution to the compromise, in the form of a four state, semi-active hydropneumatic spring-damper system, is proposed.US Government through its European Research Office of the US Army under Contracts N68171-01-M-5852, N62558-02-M-6372 and N62558-04-P-6004.http://www.elsevier.com/locate/jterrahb201

Towards Eliminating Bias in Cluster Analysis of TB Genotyped Data

The relative contributions of transmission and reactivation of latent infection to TB cases observed clinically has been reported in many situations, but always with some uncertainty. Genotyped data from TB organisms obtained from patients have been used as the basis for heuristic distinctions between circulating (clustered strains) and reactivated infections (unclustered strains). Naïve methods previously applied to the analysis of such data are known to provide biased estimates of the proportion of unclustered cases. The hypergeometric distribution, which generates probabilities of observing clusters of a given size as realized clusters of all possible sizes, is analyzed in this paper to yield a formal estimator for genotype cluster sizes. Subtle aspects of numerical stability, bias, and variance are explored. This formal estimator is seen to be stable with respect to the epidemiologically interesting properties of the cluster size distribution (the number of clusters and the number of singletons) though it does not yield satisfactory estimates of the number of clusters of larger sizes. The problem that even complete coverage of genotyping, in a practical sampling frame, will only provide a partial view of the actual transmission network remains to be explored

The Effect of Diagnostic Delays on the Drop-Out Rate and the Total Delay to Diagnosis of Tuberculosis

Background: Numerous patient and healthcare system-related delays contribute to the overall delay experienced by patients from onset of TB symptoms to diagnosis and treatment. Such delays are critical as infected individuals remain untreated in the community, providing more opportunities for transmission of the disease and adversely affecting the epidemic. Methodology/Principal Findings: We present an analysis of the factors that contribute to the overall delay in TB diagnosis and treatment, in a resource-poor setting. Impact on the distribution of diagnostic delay times was assessed for various factors, the sensitivity of the diagnostic method being found to be the most significant. A linear relationship was found between the sensitivity of the test and the predicted mean delay time, with an increase in test sensitivity resulting in a reduced mean delay time and a reduction in the drop-out rate. Conclusions/Significance: The results show that in a developing country a number of delay factors, particularly the low sensitivity of the initial sputum smear microscopy test, potentially increase total diagnostic delay times experienced by TB patients significantly. The results reinforce the urgent need for novel diagnostic methods, both for smear positive an

A Threshold Value for the Time Delay to TB Diagnosis

The original publication is available at http:/www.plosone.orgIncludes bibliographyBackgound. In many communities where TB occurs at high incidence, the major force driving the epidemic is transmission. It is plausible that the typical long delay from the onset of infectious disease to diagnosis and commencement of treatment is almost certainly the major factor contributing to the high rate of transmission. Methodology/Principal Findings. This study is confined to communities which are epidemiologically relatively isolated and which have low HIV incidence. The consequences of delays to diagnosis are analyzed and the existence of a threshold delay value is demonstrated. It is shown that unless a sufficient number of cases are detected before this threshold, the epidemic will escalate. The method used for the analysis avoids the standard computer integration of systems of differential equations since the intention is to present a line of reasoning that reveals the essential dynamics of an epidemic in an intuitively clear way that is nevertheless quantitatively realistic. Conclusions/Significance. The analysis presented here shows that typical delays to diagnosis present a major obstacle to the control of a TB epidemic. Control can be achieved by optimizing the rapid identification of TB cases together with measures to increase the threshold value. A calculated and aggressive program is therefore necessary in order to bring about a reduction in the prevalence of TB in a community by decreasing the time to diagnosis in all its ramifications. Intervention strategies to increase the threshold value relative to the time to diagnosis and which thereby decrease disease incidence are discussed. © 2007 Uys et al.Publishers' Versio

Wanopvattings by biologie-onderwysers ten opsigte van eenheidstemas in biologie-onderwys

M.Ed.This study focuses on the misconceptions that exist among teachers in the field of unifying themes in Biology teaching. The researcher feels confident that teachers are well underlain in their field of study, and that meaningful teaching occurs in Biology classes. His concern is that the fundamental unifying themes in Biology that enables pupils to reach higher cognitive levels of thought, are not utilised fully in pupils and teachers, learning and training. Investigations of these phenomena are being done through misconceptions that may occur at teachers of Biology. This forms the main aim of the study. The researcher feels that the fewer misconceptions' teachers have, the better students will be taught. Qualitative and quantitative research methods are being used to maximise the research effectiveness. Trough these methods the researcher found that teachers are well underlain in their studies but lack utilisation of unifying themes in the learning environment. Teachers concentrate on one or two themes, ignoring the remainder. The researcher hopes to make a meaningful contribution to the teaching of Biology as well as to improve the quality of teacher training programs in Biology didactic courses through awareness of these phenomena

'n Benadering vir die realisering van omgewingsopvoeding in die algemene wetenskap sillabus van graad sewe tot nege

D.Ed.Man is dependant on the environment for his essential requirements and welfare. In the current technological era our world is being irreversibly damaged through the lack of long term vision, due mainly to ignorance of the surroundings man finds himself in. This research focuses on the feasibility of Environmental Education as a perspective on the content of General Science of the compulsory school phase. The researcher feels confident that Environmental Education would indeed add a positive dimension to the future teaching of General Science. The researcher points out that Environmental Education is essential to future generations. Research is directed towards the attainability of Environmental Education in formal Education. A new-found demand faces the General Science teacher. The researcher points out that change is irrevocably due to the technological advances and development together with the adjoining dynamic expectations and demands of society. Mankind's and environment's history has clearly shown that the environment is secondary to progress. The environment must satisfy man's ever growing demands. The contrary hasn't been proven up to date. Man is insensitive to and ignorant about the demands of the environment. The corruption of a once healthy interaction between man and environment is unfortudately a result of man's impetance, insensitivity and ignorance of the environment. Therefore man must take the initiative to restore the environment to a sustainable system where man and his environment can flourish. This research proves a lack of legislation in the necessary nationwide Environmental Education. Environmental Education is far removed from its rightful place in education, not featuring in General Science but through the inclusion of the biophysical surroundings. General Science finds its roots in the biophysical dimension of the environment. The researcher has found that the total environment is only casually referred to in its political, economical and social dimensions

Image classification from EEG Brain Signals using machine learning and deep learning techniques.

Thesis (MEng)--Stellenbosch University, 2019.ENGLISH ABSTRACT: Please refer to full text for abstractAFRIKAANSE OPSOMMING: Raadpleeg teks vir opsommin