Experiment one revealed fishmeal (FM) replacement with soy protein concentrate (SPC) alone, and in combination with pea protein concentrate (PPC) and saponins (S) modulated the intestinal bacterial communities of D. labrax, increasing the presence of lactic acid bacteria. Intestinal histology revealed significantly reduced goblet cell’s (GC’s) in fish fed the SPC+S, epithelial microvilli densities (MD) in fish fed the SPC+PPC, SPC+PPC+S and SPC+S after two weeks feeding. Significant reductions in GC’s and intraepithelial leukocytes (IEL’s) in fish fed the SPC+S, and MD’s in fish fed the SPC+S and SPC+PPC+S after four weeks feeding, relative to fish fed the FM control. Furthermore, fish fed all plant based diets appeared to exhibit a loss of membrane integrity at the microvilli tips, most pronounced in fish fed the SPC+S diet. These results suggest a sub-acute enteritis response in the posterior intestine of D. labrax, which was deemed to be most pronounced in fish fed the SPC+S diets. Experiment two utilised the SPC+S diet as a sub-optimal basal diet to assess the potential of the probiotic Bacillus subtilis and the prebiotic Previda®, individually and in combination, in alleviating the enteritis-like effects induced by this diet, observed in the first experiment. Microbiological analyses revealed B. subtilis modulated the allochthonous bacterial communities. Fish fed the combination of B. subtilis and Previda® (synbiotic) diet exhibited a significantly increased intestinal perimeter ratio, compared to fish fed the basal. Significantly elevated GC’s in fish fed the probiotic and synbiotic treatments, and significantly elevated epithelial MD’s, and intestinal absorptive surface index in fish fed the probiotic diet was observed, relative to fed fish the basal. The loss of membrane integrity induced by the basal diet, was reduced in fish fed the probiotic, prebiotic and synbiotic diets. The intestinal gene expression of the pro-inflammatory cytokines IL-1β and TNFα was significantly up-regulated in fish fed all experimental diets, relative to fish fed the basal. The intestinal gene expression of HSP70, CASP3 and PCNA was significantly down-regulated in fish fed the probiotic, prebiotic and synbiotic relative to fish fed the basal. At the end of the experiment intestinal samples were exposed to one of four treatments [1. PBS (control), 2. B. subtilis, 3. Vibrio anguillarum and 4. B. subtilis + V. anguillarum], ex vivo, to determine if the feed additives could mitigate enteric pathogen damage. All feed additives revealed the potential to reduce the morphological damage caused by the pathogen. Experiment three assessed B. subtilis and the phytobiotic Next Enhance 150® on the growth and health of D. labrax. B. subtilis modulated the allochthonous bacterial communities and reduced the presence of some potential pathogens. The intestinal gene expression of HSP70, CASP3, PCNA and CAL was significantly down-regulation in fish fed the probiotic diet relative to fish fed the control. Significantly elevated IEL’s were observed in fish fed the probiotic and Next Enhance 150® diets relative to fish fed the control. Growth performance was remained unaffected. The present research demonstrates that dietary B. subtilis modulates the allochthonous bacterial communities, as well as, improving the intestinal morphology and localised immunity in European sea bass. Dietary Previda® and Next Enhance 150® were also observed to confer beneficial effects on the gut health of this species. No detrimental effects were observed as a consequence of any of the feed additives used in the present research.

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Thesis (MSc (Agric)(Production Management)) -- University of Pretoria, 2007. / Includes bibliographical references.

Call number: LD2668 .T4 1979 P6 / Master of Science

Call number: LD2668 .T4 1979 T52 / Master of Science

LD2668 .T4 1962 P57

A series of investigations were conducted in order to evaluate the effect of MOS supplementation in finfish aquaculture. Fish with great potential in aquaculture industry were tested with regards to effect of dietary MOS supplementation on intestinal histology and microbiology as well as overall animal health and production. Two levels of MOS supplementation were applied 0.2% and 0.4%. Experimental fish were Atlantic salmon (Salmon salar), rainbow trout (Oncorhynchys mykiss), sole (Solea senegalensis) and gilthead sea bream (Sparus aurata). The results from the sea bream studies revealed that MOS supplementation may have a beneficial effect on growth performance of fish greater than 100 g. Additionally, there is a systemic improvement of the intestinal histology for all species investigated, especially when using 0.4% of MOS supplementation level. Both light and electron microscopy revealed increased intestinal surface and improved intestinal integrity of MOS fed fish. MOS alters the intestinal microbiota, in the case of gilthead sea bream modulation was evident even when fish were fed 0.2% dietary MOS for as little as 2 weeks. Blood immune parameters were also affected by the MOS inclusion and total leukocytes counts were increased and leukocytes relative abundance was also changed. MOS induced intestinal microbial modulation was more evident in fish are reared in outdoor conditions. Feed utilization and digestibility were improved with the addition of 0.4% MOS supplementation in the Atlantic salmon. The sole experiment revealed that MOS could reduce fish mortalities induced by pasteurelliosis. These investigations, suggest a potential role for application of MOS in aquaculture. Future research should be conducted in order to evaluate other parameters that MOS may influence and ascertain optimum dosage for each fish species and developmental stage.

Regardless of the type of diet used, the search for increased digestion of nutrients has been the target of most research worldwide. The objective of this thesis was to evaluate the effects of the inclusion of essential oils, enzymes, ionophores and combinations of additives in animal performance, ruminal health and apparent digestibility in Nellore cattle fed with high concentrate diets. The study was composed of two performance experiments and two of metabolism In Chapter 1 of this thesis 2 experiments were conducted to evaluate the performance responses of finishing feedlot cattle receiving diets containing essential oils and exogenous enzymes. The treatments in each experiment consisted of (dry matter basis): MON - sodium monensin (26 mg/kg); BEO - a blend of essential oils (90 mg/kg); BEO+MON - a blend of essential oils plus monensin (90 mg/kg + 26 mg/kg, respectively); BEO+AM - a blend of essential oils plus exogenous α-amylase (90 mg/kg + 560 mg/kg, respectively); and BEO+AM+PRO - a blend of essential oils plus exogenous α-amylase and exogenous protease (90 mg/kg + 560 mg/kg + 840, mg/kg respectively). Exp. 1 consisted of a 93-d finishing period using 300 Nellore bulls in a randomized complete block design. Compared with MON, the combination of BEO+AM resulted in greater dry matter intake, greater average daily gain, 12 kg heavier hot carcass weight, although feed efficiency was not significantly different between BEO+AM and MON. BEO+MON and BEO did not improve performance when compared to MON. In Exp. 2, five ruminally cannulated Nellore steers were used to evaluate intake, apparent total tract digestibility of nutrients, and ruminal parameters in a 5 × 5 Latin Square design. Intakes of all nutrients measured, except for EE were greater in animals fed BEO+AM when compared with MON, with no differences on total tract nutrient digestibilities between these two treatments. Feeding BEO increased the total tract digestibility of CP compared to MON. In summary, diets containing the BEO used herein enhanced dry matter intake of growing-finishing feedlot cattle compared with a basal diet containing MON without impair feed efficiency. A synergism between BEO and AM was detected, resulting in increased carcass production. This study evaluated the growth performance and digestion responses of finishing feedlot beef cattle fed high-concentrate diets containing 82.5% flint corn (DM basis) ground to medium (1.66 mm; MG) or coarse particle sizes (2.12 mm; CG), added with monensin (26 mg/kg; DM basis; MON) or a blend of essential oils + exogenous α-amylase (90 mg/kg + 560 mg/kg commercial product, respectively, DM basis; BEO+AM). In Exp. 1, 256 Nellore bulls were blocked by initial body weight (360 ± 12 kg), assigned to 48 pens and pens within blocks were randomly assigned, in a 2 × 2 factorial arrangement, to treatments during 99 d. Feed additive effect was detected for DMI, which was greater for bulls fed BEO+AM vs. MON. The HCW was 11 kg heavier for bulls fed BEO+AM vs. MON in diets containing CG, but not MG particle size. In Exp. 2, four ruminally cannulated Nellore steers were offered the same treatments of Exp. 1, in a 4 × 4 Latin Square design, to evaluate intake, apparent total tract digestibility of diets and ruminal fermentation parameters. Effect of corn particle size was detected for intake of DM, CP, NDF, NFC, starch and TDN which were greater for steers fed CG than steers fed MG corn. Feed additive affected (P = 0.02) ruminal NH3-N concentration, which was less for steers fed BEO+AM compared to MON. In summary, reducing flint corn particle size from 2.12 to 1.66 mm in finishing diets failed to improve cattle growth performance, digestibility of most nutrients and ruminal fermentation characteristics. A blend of essential oils associated with exogenous α-amylase resulted in the heavier carcass weights compared to monensin supplementation when included in diets containing coarse ground corn. / Independente do tipo de dieta utilizada, a busca por aumento da digestão dos nutrientes tem sido alvo da maior parte das pesquisas realizadas no mundo. O objetivo dessa tese foi avaliar os efeitos da inclusão de óleos essenciais, enzimas, ionóforos e combinações de aditivos na performance animal, saúde ruminal e digestibilidade aparente em bovinos de corte da raça Nelore confinados alimentados com dietas de terminação com alto concentrado. O estudo foi composto por dois experimentos de desempenho e dois de metabolismo. No Capítulo 1 dessa tese 2 experimentos foram conduzidos para avaliar o desempenho de bovinos terminados em confinamento recebendo dietas que continham óleos essências e enzimas exógenas. Os tratamentos em cada experimento consistiram em: MON (monensina sódica, 26 mg/Kg); BEO (blend de óleos essenciais - 90 mg/kg); BEO+MON; BEO+AM (blend de óleos essenciais mais α-amilase - 90 mg/kg + 560 mg/kg, respectivamente) e BEO+AM+PRO (óleos essenciais mais α-amilase mais protease (90 mg/kg + 560 mg/kg + 840 mg/kg, respectivamente). No Exp. 1 foram utilizados 300 animais Nelore distribuídos aleatoriamente em 60 baias. Comparado com MON, a combinação BEO+AM resultou em maior CMS, maior GPD e proporcionou 12 kg a mais de carcaça, sem alterar a eficiência alimentar. BEO+MON e BEO não proporcionaram melhora no desempenho, quando comparada com MON. No Exp. 2, 5 animais canulados no rúmen foram usados para avaliar, CMS, digestibilidade aparente dos nutrientes e parâmetros ruminais em um quadrado latino 5 x 5. BEO aumentou a digestibilidade no trato total da PB comparada com MON. Os consumos de todos nutrientes, com exceção de EE foram maiores para animais alimentados com BEO+AM, quando comparados com MON, sem diferenças na digestibilidade no trato total. Em resumo, BEO aumenta o CMS de animais confinados em relação a MON, sem alterar a eficiência alimentar. Um sinergismo entre BEO e AM foi observado, resultando em aumento da produção de carcaça. No Capítulo 2, avaliou-se o desempenho e respostas metabólicas de animais confinados recebendo dietas com alto teor de milho (82.5% da MS), processado em moído (1,66 mm; MG) e moído grosso (2,12 mm; CG), combinado com monensina (monensina sódica, 26 mg/Kg; MON) ou com blend de óleos essenciais mais α-amilase (90 mg/kg + 560 mg/kg, respectivamente; BEO+MON). No Exp. 1, 256 animais Nelore foram blocados em 48 baias, as quais foram distribuídas aleatoriamente a um arranjo fatorial 2 x 2 nos tratamentos por 99 dias. Animais alimentados com BEO+MON apresentaram maior CMS do que animais alimentados com MON. Foi observada interação entre processamento e aditivo para PCQ, na qual animal alimentados com BEO+MON e CG obtiveram 11 kg a mais. No Exp. 2, quatro animais canulados no rúmen foram assimilados as mesmos tratamentos do Exp. 1, em um quadrado latino 4 x 4. Efeito de processamento foi detectado no consumo de MS, PB, FDN, CNF, amido e NDT, os quais foram maiores para animais alimentados com milho CG do que MG. Efeito de aditivo foi observado na concentração de NH3-N ruminal, a qual foi menor para animais alimentados com BEO+AM comparado a animais que receberam MON. Em suma, reduzir o tamanho de partícula de 2,12 mm para 1,66 mm não melhorou o desempenho e os parâmetros de fermentação ruminal. A suplementação com BEO+AM resulta em maior produção de carcaça comparada com monensina, quando incluída em dietas com milho moído grosseiramente.