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In this study, 14 typical South African feedlot bulls received no beta-adrenergic agonist for the last 30 days of the finishing period (C), 14 received 120 mg R-salbutamol per animal per day for the last 30 days of the finishing period (S30), 13 received 120 mg Rsalbutamol per animal per day for the last 40 days of the finishing period (S40) and the last group of 13 bulls received 60 mg zilpaterol hydrochloride per animal per day for the last 30 days of the finishing period (Zh). All animals were slaughtered after a 3-day withdrawal period. Parameters included weight gain, feed intake, feed conversion rate, warm and cold carcass mass, dressing %, subcutaneous fat thickness, hide yield %, internal carcass fat distribution, % bone, % fat and % muscle of the prime rib-cut, carcass classification code, conformation, compactness, post-mortem carcass pH profiles, cooking loss, shear force, blood urea nitrogen, creatinine and residue levels of the beta-adrenergic agonists. No differences were observed between any of the four treatment groups concerning live feedlot performance. Bulls receiving the S30 and Zh treatments had lower internal carcass fat distribution compared to C bulls (P <0.05). Bulls receiving the S40 treatment had a lower % fat in the prime rib-cut compared to Zh bulls (P <0.05). Carcasses from S30 bulls had higher pH values 24 hours post mortem compared to carcasses from Zh bulls (P <0.01). Meat samples from Zh bulls had higher shear force, which indicates less tender meat, compared to samples from S40 bulls (P <0.05). Change in serum creatinine levels increased only in Zh treated bulls from the start to the end of treatment and may reflect a higher protein turnover in Zh bulls. The results of this study indicate that R-salbutamol has a more pronounced effect on fat metabolism in feedlot bulls compared to zilpaterol hydrochloride, while zilpaterol hydrochloride has a more pronounced effect on protein metabolism. The residue levels in samples of the liver, kidney, muscle and feaces from zilpaterol hydrochloride and R-salbutamol treated bulls were well below acceptable limits. / Dissertation MSc(Agric)--University of Pretoria, 2014 / gm2015 / Animal and Wildlife Sciences / MSc(Agric) / Unrestricted

Foram utilizados 24 cordeiros cruzados Ile de France, com peso médio inicial de 22,27 ± 1,85 kg e, aproximadamente, 80 dias de idade, suplementados com os níveis 0 (controle); 0,3; 0,9 e 2,7 g/kg de MS de produto enzimático comercial, contendo amilase, celulase, fitase, xilanase, betaglucanase, pectinase e protease, adicionado no momento da mistura do concentrado. O desempenho animal não foi afetado pela adição das enzimas, com médias de 37,3 ± 4,3 kg; 1,182 ± 0,153 kg/dia; 0,356 ± 0,077 kg/dia e 3,3 ± 0,3 para o PVF, IMS, GPD e CA, respectivamente. Para a digestibilidade da MS, FDN, FDA, PB, EE, NDT e amido, as médias foram, respectivamente, 80,55; 60,14; 58,80; 81,55; 52,02; 83,16 e 98,20%. A Digestibilidade da FDN apresentou uma tendência de aumento linear conforme o acréscimo do nível de enzima, com uma melhora de 11% para o último nível, em relação ao controle. As demais variáveis não foram alteradas. As concentrações de fósforo e glicose plasmáticos não foram alteradas pela enzima. O protozoário do gênero Entodinium sp. representou mais de 95% do total de ciliados para todos os tratamentos avaliados, e os dados se ajustaram ao efeito quadrático, com o nível de 2,18 kg de enzima/kg de MS proporcionando maior crescimento destes. Para o pH ruminal ao abate, não houve influência das enzimas. Os rendimentos de carcaça quente e fria apresentaram uma queda até os níveis de 1,61 e 1,55 g de enzima/kg de MS, respectivamente, sendo que, após estes valores, os rendimentos se aproximaram novamente do controle. A adição de níveis crescentes de enzimas diminuiu a perda de água por exsudação, mas não afetou a perda por cocção e a maciez da carne de cordeiros. Portanto, apesar da melhora em alguns parâmetros, o desempenho dos animais, bem como as características de carcaça e da carne, não foram afetados pela adição das enzimas, sendo que, para ovinos, o complexo enzimático avaliado não é eficaz sob as mesmas condições experimentais. / Twenty-four crossbred lambs Ile de France, with initial average body weight of 22,7 ± 1,85 kg and age of 80 days, were supplemented with 0 (control treatment); 0,3; 0,9 e 2,7 g/kg DM levels of enzymatic commercial product, with amylase, cellulose, phytase, xylanase, glucanase, pectinase e protease, added at the moment of concentrate mixing. Performance was not affected by enzyme complex supplement,, with averages of 37,3 ± 4,3 kg; 1,182 ± 0,153kg/day, 0,356 ± 0.077 kg/day and 3,3 ± 0,3 for FLW, DMI, ADG and FC, respectively. For DM, NDF, ADF, CP, EE, TDN and starch, the averages were, respectively, 80,55;60,14; 58,80; 81,55; 52,02; 83,16 and 98,20%. There was observed a tendency to FDN digestibility with linear increasing as the enzyme levels increased, with an improvement of 11% for the last level, compared to control diet. All the others variables were not changed. Glucose and phosphorus concentrations were not affected by the enzyme complex. The Entodinium sp. protozoa represented more than 95% of the total ciliated protozoa for all treatments studied and the data were adjusted by the quadratic effect, with the level of 2,18 kg of enzyme/kg of DM showing a better growing of those. Ruminal pH at the slaughter, was not affected by enzymes. Hot dressing percentage and cold dressing percentage decreased until levels of 1,61 and 1,55 g of enzyme/kg of DM, respectively, even when after these data, dressing percentage went back closely to the control treatment. The increasing levels addition of enzyme decreased drip loss, but did not affect the cocking loss and tenderness of lambs meat. Despite the improvement of some parameters, as well as performance, meat and carcass characteristics, were not affect by the enzymes, suggesting that enzyme complex analyzed was not efficient at the same experimental conditions for sheep.

Foram utilizados 24 cordeiros cruzados Ile de France, com peso médio inicial de 22,27 ± 1,85 kg e, aproximadamente, 80 dias de idade, suplementados com os níveis 0 (controle); 0,3; 0,9 e 2,7 g/kg de MS de produto enzimático comercial, contendo amilase, celulase, fitase, xilanase, betaglucanase, pectinase e protease, adicionado no momento da mistura do concentrado. O desempenho animal não foi afetado pela adição das enzimas, com médias de 37,3 ± 4,3 kg; 1,182 ± 0,153 kg/dia; 0,356 ± 0,077 kg/dia e 3,3 ± 0,3 para o PVF, IMS, GPD e CA, respectivamente. Para a digestibilidade da MS, FDN, FDA, PB, EE, NDT e amido, as médias foram, respectivamente, 80,55; 60,14; 58,80; 81,55; 52,02; 83,16 e 98,20%. A Digestibilidade da FDN apresentou uma tendência de aumento linear conforme o acréscimo do nível de enzima, com uma melhora de 11% para o último nível, em relação ao controle. As demais variáveis não foram alteradas. As concentrações de fósforo e glicose plasmáticos não foram alteradas pela enzima. O protozoário do gênero Entodinium sp. representou mais de 95% do total de ciliados para todos os tratamentos avaliados, e os dados se ajustaram ao efeito quadrático, com o nível de 2,18 kg de enzima/kg de MS proporcionando maior crescimento destes. Para o pH ruminal ao abate, não houve influência das enzimas. Os rendimentos de carcaça quente e fria apresentaram uma queda até os níveis de 1,61 e 1,55 g de enzima/kg de MS, respectivamente, sendo que, após estes valores, os rendimentos se aproximaram novamente do controle. A adição de níveis crescentes de enzimas diminuiu a perda de água por exsudação, mas não afetou a perda por cocção e a maciez da carne de cordeiros. Portanto, apesar da melhora em alguns parâmetros, o desempenho dos animais, bem como as características de carcaça e da carne, não foram afetados pela adição das enzimas, sendo que, para ovinos, o complexo enzimático avaliado não é eficaz sob as mesmas condições experimentais. / Twenty-four crossbred lambs Ile de France, with initial average body weight of 22,7 ± 1,85 kg and age of 80 days, were supplemented with 0 (control treatment); 0,3; 0,9 e 2,7 g/kg DM levels of enzymatic commercial product, with amylase, cellulose, phytase, xylanase, glucanase, pectinase e protease, added at the moment of concentrate mixing. Performance was not affected by enzyme complex supplement,, with averages of 37,3 ± 4,3 kg; 1,182 ± 0,153kg/day, 0,356 ± 0.077 kg/day and 3,3 ± 0,3 for FLW, DMI, ADG and FC, respectively. For DM, NDF, ADF, CP, EE, TDN and starch, the averages were, respectively, 80,55;60,14; 58,80; 81,55; 52,02; 83,16 and 98,20%. There was observed a tendency to FDN digestibility with linear increasing as the enzyme levels increased, with an improvement of 11% for the last level, compared to control diet. All the others variables were not changed. Glucose and phosphorus concentrations were not affected by the enzyme complex. The Entodinium sp. protozoa represented more than 95% of the total ciliated protozoa for all treatments studied and the data were adjusted by the quadratic effect, with the level of 2,18 kg of enzyme/kg of DM showing a better growing of those. Ruminal pH at the slaughter, was not affected by enzymes. Hot dressing percentage and cold dressing percentage decreased until levels of 1,61 and 1,55 g of enzyme/kg of DM, respectively, even when after these data, dressing percentage went back closely to the control treatment. The increasing levels addition of enzyme decreased drip loss, but did not affect the cocking loss and tenderness of lambs meat. Despite the improvement of some parameters, as well as performance, meat and carcass characteristics, were not affect by the enzymes, suggesting that enzyme complex analyzed was not efficient at the same experimental conditions for sheep.