Thesis (PhD(Agric))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Exogenous fibrolytic enzymes (EFE) as additives in ruminant feeds are being researched worldwide. Promising effects on dry matter intake (DMI), digestibility and production in especially dairy cows, but also feedlot steers and even sheep have been observed. However, lack of or negative effects are also reported and the need arises for clarity on the mode-of-action of EFE. Forages are characterised as being highly heterogenic and contain varying concentrations of fibre. The fibre, in turn, varies greatly in digestibility, due to the chemical as well as anatomical build-up of this complex carbohydrate. Fibre, however, presents a major source of potential energy for ruminant animals and EFE is a viable option to increase the digestibility of forages. Therefore, a study with the aim of establishing whether EFE can affect the digestibility of forages, how it affects the digestibility and the clarification of the mode-of-action was drafted. From the literature, the first objective was readily attained and clear indications exist that EFE can indeed improve animal performance when their diets are treated with such enzymes. From the current study, it was shown that EFE can alter the rate and extent of gas production of certain forages (lucerne, kikuyu and weeping love grass) and also improve the in vitro digestibility thereof (P < 0.05). This is in agreement with other research findings and it was concluded that these effects were likely exerted during the early stages of digestion. A complete feed for sheep, when treated with the EFE, showed positive effects on the in sacco digestibility, as well as on the digestion kinetics of the feed (P < 0.05). The in vitro digestibility of the complete feed was also improved due to EFE treatment (P < 0.05). The observations on in vitro digestibility were less marked when a purified xylanase, obtained from the partial purification of the EFE cocktail, was used as the sole fibrolytic enzyme treatment. It is apparent, therefore, that enzyme specificity plays a major role in obtaining positive effects on digestibility of forages and feeds. In agreement with the literature, it is proposed that the approach to improve the digestibility of forages should be to use EFE cocktails containing various enzymes, matching the complexity of the substrate. The major aim of the study was, however, an in depth investigation of the mode-of-action of EFE. This aim was approached by observing changes in plant tissue material at the histological level upon treatment with EFE and incubation in buffered rumen fluid. Results showed that EFE had subtle, yet significant effects on cell wall material for the various tissues studied (P < 0.05). The major effect observed here was that EFE had a thinning effect on the cell wall thickness (P < 0.05). It was deduced that as EFE affected the cell wall of the plant material, earlier access by microorganisms could be achieved. Also, nutrients caught in the cell wall matrix could then be released for digestion. Therefore, observations that EFE increases the rate of digestion, as well as the extent of digestion of not only fibre, but also protein, were explained by the enzyme’s action on cell wall material. It was concluded that there is definite merit in the use of EFE to improve the digestibility of ruminant feeds and that this is partly related to effects on the cell walls of the forages. The effects can be expected to occur during the early stages of digestion, thereby potentially increasing the passage rate of digesta from the rumen. Additionally, the effect of the EFE is not limited to fibre and increased digestibility of all nutrients can be expected, thereby increasing the overall digestibility of the feed. Future research should further elucidate the mode-of-action of EFE using advanced technologies routinely employed in the plant sciences. Additionally, the main potential advantage of EFE treatment lies in improving the digestibility of poor quality roughages. Unfortunately, this is an area where limited positive effects are observed and in depth investigations should be undertaken to classify the specificity and optimum conditions of EFE to better match the complexity of the substrate being treated. / AFRIKAANSE OPSOMMING: Eksogene fibrolitiese ensieme (EFE) word tans wêreldwyd ondersoek vir die gebruik daarvan as voerbymiddels vir herkouers. Belowende effekte op DMI, verteerbaarheid en produksie van vernaam melkbeeste, maar ook voerkraalbeeste en selfs skape is al gerapporteer. Swak en selfs negatiewe effekte word egter ook waargeneem en daarom is ʼn deeglike ondersoek na die metode van werking van EFE van belang. Ruvoere word gekenmerk deurdat dit heterogeen van aard is en bevat variërende vlakke van vesel. Vesel maak op sy beurt ʼn wesenlike deel uit van die ruvoer, maar varieer baie in verteerbaarheid weens die chemiese sowel as anatomiese samestelling van hierdie komplekse koolhidraat. Ruvoer verteenwoordig egter ʼn goeie bron van potensiële energie vir herkouers en EFE word voorgestel as ʼn haalbare behandeling om die verteerbaarheid daarvan te verhoog. Dus is ʼn studie beplan met die doelwit om die effekte van EFE te definieer, hoe dit verteerbaarheid beïnvloed en die metode van werking daarvan te ondersoek. Vanuit die literatuur is dit duidelik dat daar wel baie positiewe effekte is waar ruvoere met EFE behandel is en dat diereproduksie wel bevoordeel word daardeur. Vanuit die studie is dit getoon dat die tempo en hoeveelheid gasproduksie van sekere ruvoere (lusern, kikuyu en oulandsgras) verbeter word deur EFE behandeling (P < 0.05). Hierdie bevinding was ondersteun deur verbeterde in vitro verteerbaarheid van die ruvoere (P < 0.05). Dit is in ooreenstemming met literatuur en die gevolgtrekking is gemaak dat hierdie effekte tydens die vroeëre stadia van vertering verwag kan word. ʼn Volledige skaapvoer wat met EFE behandel is, het positiewe effekte op in sacco verteerbaarheid en verterings kinetika data gehad (P < 0.05). Weereens is die in vitro verteerbaarheid van die voer verbeter (P < 0.05). Waarnemings op in vitro verteerbaarheid was veel minder opvallend wanneer ʼn gesuiwerde xylanase as enigste fibrolitiese ensiem behandeling gebruik is. Dit is dus duidelik dat ensiem spesifisiteit ʼn belangrike rol speel in die verkryging van positiewe resultate in die verteerbaarheid van ruvoere en veevoere. In ooreenstemming met literatuur word dit voorgestel dat ensiemmengsels wat verskeie ensieme bevat as EFE gebruik behoort te word ten einde aan die kompleksiteit van die substraat te voldoen. Die hoof doelwit van die studie was egter ʼn indiepte ondersoek na die metode van werking van EFE. Hierdie doelwit is benader deur die effekte van EFE op selwand strukture van plantmateriaal op ʼn histologiese vlak te ondersoek. Die ruvoere was vooraf met EFE behandel en in vitro geïnkubeer in rumen vloeistof. Die resultate het getoon dat EFE ʼn matige, dog betekenisvolle effek op die selwand materiaal van die onderskeie weefsels gehad het (P < 0.05). Die belangrikste waargeneemde effek was dat EFE ʼn verdunningseffek op die selwande gehad het. Dit is afgelei dat as EFE die selwand kan beïnvloed, mikro-organismes vroeër toegang tot die inhoud kan kry. Verder, nutriënte vasgevang in die selwand matriks raak ook beskikbaar vir vertering. Hierdie afleiding en die effek van EFE op selwande verklaar waarnemings dat EFE die tempo van vertering sowel as die vlak van vertering van nie net vesel, maar ook proteïen kan bevoordeel. Die gevolgtrekking is gemaak dat daar definitiewe meriete is in die gebruik van EFE om die verteerbaarheid van herkouervoere te verbeter en dat dit verband hou met die ensiem se werking op selwande van die ruvoere. Die effekte kan verwag word tydens die vroeë stadia van vertering om dus deurvloeitempo van digesta te verbeter. Die effek van die EFE is verder nie beperk tot vesel nie, maar positiewe effekte op ander nutriënte kan verwag word en vervolgens ʼn algehele verhoging in die verteerbaarheid van die voer. Navorsing behoort in die toekoms verder die metode van werking van EFE te ondersoek deur gebruik te maak van gevorderde tegnologie wat alledaags gebruik word in die Plantwetenskappe. Die belowendste aanwending van EFE lê in die verbetering in vertering van swak kwaliteit ruvoere. Dit is ongelukkig juis hier waar min positiewe resultate gerapporteer word en indiepte navorsing moet onderneem word om ensiem spesifisiteit en optimum kondisies te definieer sodat EFE beter opgewasse is teen die kompleksiteit van die substraat.

Physicochemical properties of different fibrous ingredients were used to determine the influence of feed bulk on voluntary feed intake and gut capacity in weaner and finishing pigs. Physicochemical measures of bulkiness determined on feed ingredients were DM, crude protein (CP), ether extract, ash, water holding capacity (WHC), bulk density, crude fibre (CF), neutral detergent fibre (NDF) and acid detergent fibre (ADF). Among the fibre sources, maize stover had the highest WHC, followed by veld grass, then lucerne hay, maize cob, sunflower husks, groundnut haulms, rice bran and saw dust. The greatest bulk densities (1.4 g DM/ml) were observed in lucerne hay and saw dust, whilst sunflower husk had the lowest (0.7 g DM/ml) (P < 0.001). Rice bran, maize cob and groundnut haulms were the most fermentable fibrous ingredients (P < 0.05). Based on differences in physicochemical properties, six fibres namely lucerne hay, maize cob, maize stover, veld grass, saw dust and sunflower husk were selected and used in formulating fibrous diets fed to growing pigs based on wideness in ranges of their bulk properties. Thirty-one complete diets were formulated by dilution of a conventional weaner feed with increment levels of each fibre source at 0, 80, 160, 240, 320 and 400 g/kg. Each of the diets was offered ad libitum to four of 124 pigs weighing 18.1 (s.d. 1.37) kg body weight, in individual pens, for four weeks. There was a linear decrease in scaled feed intake (SFI) (P < 0.001) as bulk density of the feeds increased. There was a quadratic relationship between SFI and WHC, NDF and ADF, respectively, whereby SFI increased up to a point when it reached its maximum and then started to decrease as bulkiness increased (P < 0.001). By use of the broken stick model, the maximum SFI marking the gut capacity of pigs was attained when WHC = 4.5 ± 1.25 g water/g DM (P< 0.001), NDF = 367 ± 29 g/kg DM (P < 0.001) and ADF = 138 ± 77 g/kg DM (P < 0.01), respectively. The SFI decreased linearly with an increase in bulk density of the feeds (P < 0.001). Four of 84 finishing pigs in individual pens, at 65 (s.d. 1.37) kg body weight were given, ad libitum to each of 21 diets containing graded levels of lucerne, maize cobs, saw dust and sunflower husk. There was a linear decrease in SFI (P < 0.001) as WHC increased. There was a quadratic decrease in SFI as CF (P < 0.001) and NDF (P < 0.01) increased. As CP increased, there was a quadratic increase in SFI (P < 0.01). In weaner pigs, an increase in WHC, NDF, ADF and bulk density constrains feed intake, thereby providing relationships that can be used to predict gut capacity. Conversely, measurements of feed bulk cannot provide relationships with intake that can be used to predict gut capacity in finishing pigs. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg.

Physicochemical properties of fibre-based diets were used to determine the influence of feed bulk on physicochemical properties of digesta within each segment of the gastrointestinal tract and digesta in pigs. In the first experiment, three pigs (14 ± 1.2 kg body weight (BW) were allocated to each of six diets containing maize cob levels at 0, 80, 160, 240, 320 and 400 g/kg DM inclusion levels for four weeks. All pigs were fed ad libitum. They were slaughtered, eviscerated and weights of the gut compartments were recorded, then contents of digesta from each segment were sampled for the determination of water concentration, water holding capacity (WHC) and swelling capacity (SWC). The WHC of digesta in the stomach, ileum and caecum decreased (P < 0.05) with maize cob inclusion level. The SWC in the stomach decreased with the inclusion level of maize cob meal. The SWC of caecal digesta increased with maize cob inclusion (P < 0.05). Physicochemical properties of digesta increased (P < 0.05) from the stomach to ileum then decreased as the digesta moved through the hindgut. In the second experiment, four fibres namely maize cob, lucerne hay, sunflower husk and citrus pulp were used. These fibres were used in formulating diets for finishing pigs. Twenty-one complete diets were formulated by dilution of a conventional feed with increment levels of each fibre source at 0, 80, 160, 240, 320 and 400 g/kg. Each of the diets was offered ad libitum to four of 84 pigs weighing 80.8 ± 8.15 kg body weight, in individual pens, for 30 days. Stomach weights increased linearly with an increase in neutral detergent fibre (NDF) but increased with quadratic functions with an increase in SWC of the diet (P <0.05). An increase in WHC of the fibrous diets increased linearly the WHC of the proximal colon (P <0.01) at a faster rate compared to the WHC of the distal colon (P <0.001). As the SWC of the diets increased, linear increases in SWC of the digesta in the stomach (P <0.01) and caecum (P <0.001) were observed. The WHC of the digesta was negatively correlated to SWC (P < 0.001) in the stomach. Scaled feed intake (SFI) decreased linearly with an increase in SWC of the diet (P < 0.001). There was no relationship between WHC of the diet and SFI (P > 0.05). There was a linear decrease (P < 0.01) in SFI of finishing pigs as the SWC of the digesta. It can be concluded that the swelling capacity of the diets and stomach digesta in stomach are accurate predictors of scaled feed intake. Swelling capacity had great influence in the stomach weights whilst other bulking properties, such as WHC and neutral detergent fibre, affected the weight and digesta properties in the caecum, proximal and distal colon. / M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.

No description available.

The broad objective of the study was to determine feeding behaviour and gut health of pigs fed different fibres at varying inclusion levels. Maize cob, maize stover, sunflower hulls, veld grass, sawdust, lucerne and dried citrus pulp were used in growing and finishing pig diets to provide a wide range of physicochemical properties. Time spent eating, drinking, lying down, sitting/standing and other activities was observed using video cameras. Blood samples were collected at the end of the trial for both growing and finishing pigs for analysis of glycated haemoglobin, albumin, globulin, total protein, creatine kinase, urea and uric acid. Intestinal segments were collected at the end of trial for growing pigs to determine mucosal architecture of the intestines. Digestible energy (DE), bulk density (BD), acid detergent fibre (ADF) and water holding capacity (WHC) were the most important variables predicting time spent on different behavioural activities in growing pigs (P < 0.001). Water holding capacity, neutral detergent fibre (NDF) and ADF were the most important variables involved in predicting time spent on different behavioural activities in finishing pigs (P < 0.001). Physicochemical properties influenced time spent on different behavioural activities and they provided relationships with time spent on different behavioural activities in both growing and finishing pigs. Glycated haemoglobin, albumin, globulin, total protein and uric acid were factors that influenced time spent eating in growing pigs (P < 0.05). In finishing pigs, only serum total protein was selected as the best predictor variable influencing time spent eating (P < 0.05). The blood metabolites were correlated with time spent eating and drinking. They provided threshold values with time spent eating and drinking by pig. Hence, they can also be used as potential biomarkers that modulate neuronal pathways which reduce time spent eating and drinking. In this study, bulk density (BD) and NDF were the best predictor variables influencing villi height (VH) and apparent villi surface area (AVSA) in pigs (P < 0.05). Grouped pigs fed fibrous diet spent more time eating, lying down, standing, walking and fighting (P < 0.05). Skin lesions appeared the most on neck and shoulder region followed by chest, stomach and hind leg region, and finally head region (P < 0.05). Fibrous diet did not reduce aggressive behaviours, rather aggressive behaviours emanated out of frustration when queuing at the feeder. It was concluded that physicochemical properties of fibrous diets and nutritionally-related blood metabolites influence feeding behaviour. Mucosal architecture was also influenced by physicochemical properties of the fibrous diets. / Ph.D. University of KwaZulu-Natal, Pietermaritzburg 2013.

A study was conducted to test the effects that different high fibre sources and their varying inclusion levels had on the characteristics of the excreta (faeces, urine and the slurry), and on odour from the slurry of growing pigs. Faeces and urine characteristics were tested from 52 pigs fed rations containing grass hay (GH), lucerne hay (LH), maize cobs (MC), maize stover (MS) and sunflower husk (SH) diets at inclusion levels up to 400 g/kg as fed basis. Faecal output, faecal consistency and nitrogen were influenced by fibre type (P <0.01) and inclusion level (P <0.01). Nitrogen content in faeces and urine was also affected by dietary fibre inclusion. Increasing fibre inclusion levelled to a reduction in urinary nitrogen content, indicating nitrogen repartitioning from urine to faeces, thereby minimizing nitrogen volatilization. The slurry from pigs fed on LH, MC and SH at levels up to 160 g/kg was tested for chemical composition and odour offensiveness. The slurry was incubated for 16 days. The pH and nitrogen content varied among fibre types and incubation period (P <0.05). Isobutyrate and butyrate concentrations varied with fibre type and the incubation period tested (P <0.01). Using panellists, the SH containing rations resulted in low odour offensiveness score. Maize cob-containing diets resulted in the largest odour scores, with (mean rank of 2.2 and 4.3 for SH and MC, respectively). To reduce odour offensiveness from piggeries, sunflower husk was recommended as an alternative feed ingredient for growing pigs. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

La fibra di canapa europea è l'unica fibra naturale con una certificazione di sostenibilità. La qualità della fibra è influenzata principalmente da genotipo, tecniche agronomiche, epoca di raccolta e metodo di macerazione. L'obiettivo principale della tesi è delineare le pratiche agronomiche e di post-raccolta per migliorare l'estrazione e la qualità della fibra, con particolare attenzione alla produzione di canapa multiuso ritardando la raccolta fino alla maturazione dei semi. Le prove di densità, fertilizzazione azotata e varietali sono state condotte in differenti ambienti Europei. La procedura di decorticazione standardizzata è stata confrontata con la linea longitudinale di estrazione della fibra per applicazioni di alto valore aggiunto. I test su bio-compositi di canapa sono stati effettuati con fibra pettinata per confrontarne le proprietà tra genotipi, epoca di raccolta e metodi di macerazione. I risultati di questa indagine suggeriscono che i) la densità di semina e la concimazione azotata ottimale sono tra 90-150 piante m-2 e 30-60 kg N ha-1; ii) le nuove varietà dallo stelo giallo presentano un'alta efficienza di decorticazione e una ridotta contaminazione da canapulo nella fibra, iii) la fibra di canapa, con proprietà comparabili a quelle del lino, si è dimostrata adatta per applicazioni in compositi di alto valore. / European hemp fibres are the only natural fibre with an established sustainability certification. Hemp fibre quality is affected by genotype, agronomic techniques, harvest time and retting method. The main objective of this thesis is to outline the agronomic and post-harvest practices for improved fibre extraction and fibre quality, with special attention to multipurpose hemp production delaying the harvest from the flowering stage until seed ripening is complete. Planting density and nitrogen fertilization trials and variety trials were conducted in contrasting environments in Europe. Stems were decorticated following a standardised procedure and longitudinal hemp line for textile and high-added values application was compared with lab-scaled decortication. Impregnated fibre bundle tests were carried out with hemp hackled fibre bundles to compare composites and back-calculated fibre properties between genotypes, harvest times and retting methods. Results of this investigation suggest that i) optimum plant density and nitrogen fertilization are between 90 and 150 plants m-2 and 30 and 60 Kg N ha-1 respectively; ii) new yellow stemmed varieties are characterized by high decortication efficiency and relative high cleanness of the extracted fibre and iii) long hemp fibre, having properties comparable to those of flax, proved to be suitable for high-tech composites applications.