A utilização do corticosteróide antenatal objetivando induzir artificialmente a maturação fetal e garantir a sobrevivência de neonatos críticos é bem estabelecido e rotineiramente utilizado em Medicina. Por outro lado, a utilização pós-natal de corticóide, como garantia de melhores condições clínicas do neonato, ainda figura como expressivo desafio tanto em neonatologia humana quanto veterinária. Deste modo, este estudo tem como objetivo avaliar a eficácia da corticoterapia pré ou pós-natal em cordeiros prematuros extremos na melhora da condição clínica, pulmonar, metabólica e hemodinâmica; necessidade de assistência ventilatória e na garantia de sobrevivência neonatal. Para tal, cordeiros prematuros, nascidos aos 135 dias de gestação, foram aleatoriamente alocados nos grupos: corticoterapia materna pré-natal (CORT PRÉ; n=8), corticoterapia pós-natal (CORT PÓS; n=9) e controle (CONT; n=5). A corticoterapia foi realizada com betametasona em dose única de 0,5 mg/Kg, por via de aplicação intra muscular, aos 133 dias de gestação ou aos 10 minutos após o nascimento para os grupos CORT PRÉ e CORT PÓS, respectivamente. O parto foi induzido utilizando-se o fármaco aglepristona às 49 horas prévias à data estimada para o parto. Os neonatos foram avaliados quanto ao escore Apgar, condição clínica geral (freqüência cardíaca, freqüência respiratória, tônus muscular e irritabilidade reflexa), temperatura corpórea, hemogasometria arterial, glicemia, lactatemia, concentrações séricas das enzimas antioxidantes (superoxido dismutase SOD e glutationa peroxidase GPx) e marcador do estresse oxidativo (TBARS) em 10 momentos pontuais durante os 3 dias subsequentes ao parto. Para os cordeiros destinados ao suporte ventilatório, avaliamos o tempo (em minutos) necessário para o início do protocolo ventilatório a partir do nascimento e o tempo de permanência na ventilação. Os dados foram analisados por meio de testes paramétricos e não-paramétricos, com nível de significância de 95%. As variáveis também foram submetidas ao teste de correlação de Spearman. Como resultados, observamos melhor condição de vitalidade e tônus muscular nos neonatos tratados em relação ao grupo controle. Quanto à avaliação cardiogênica, a betametasona pré-natal apresentou efeito bradicárdico, enquanto a administração pós-natal resultou em efeito taquicárdico. Tanto os resultados de frequência respiratória como temperatura corpórea foram estatisticamente superiores nos neonatos tratados em relação ao controle. Todos os cordeiros nasceram bradicárdicos e bradipneicos, com valores normais atingidos a partir de 10 minutos. Observamos hiperglicemia nos grupos tratados, com valor estatisticamente superior no grupo CORT PÓS. O valor de lactato foi estatisticamente superior no grupo CORT PÓS em relação ao controle. Quanto aos componentes do equilíbrio ácido-básico, os neonatos do grupo CORT PRÉ tiveram valores significativamente maiores de bicarbonato, enquanto menores pressões de CO2 foram observadas a partir de 60 minutos, embora sem diferença quanto ao pH e BE. Os tratamentos não determinaram alterações nos valores de PO2 e SO2. Entretanto, os diferentes protocolos corticoterápicos influenciaram no perfil hematológico neonatal, com valores significativamente maiores de hematócrito no grupo CORT PÓS, seguido pelo grupo CORT PRÉ. Observamos também atuação do tratamento pós-natal nos valores de SOD e correlação positiva com os valores de hematócrito e hemoglobina. Comparando-se o percentual de cordeiros submetidos à assistência ventilatória, verificou-se maior necessidade no grupo controle. Os neonatos do grupo CORT PRÉ permaneceram por tempo menor sob assistência ventilatória, em relação ao grupo controle Com base nos resultados obtidos, concluímos que a corticoterapia pós-natal ou pré-natal favorece a condição clínica neonatal (vitalidade, tônus muscular e funções vitais), a função pulmonar (trocas gasosas e compensação aos desequilíbrios ácido-básicos) e a atividade metabólica (controle glicêmico). O tratamento pós-natal aumentou a atividade da enzima SOD, reduzindo os riscos de danos pulmonares. Ainda, o tratamento com betametasona pós-natal ou materna pré-natal diminui a necessidade de assistência ventilatória em cordeiros prematuros extremos / The use of corticosteroid aiming artificially fetal lung maturation and survival of critical neonates is used as a routine in medicine. On the other hand, the postnatal steroid therapy used to improve clinical conditions of the newborn, It\'s still a therapeutic challenge both in human as veterinary neonatology. Thus, the aims this study is to assess the effectiveness of corticosteroid, used in the pre or postnatal period, in extremely preterm lambs to improve clinical, pulmonary, metabolic and hemodynamic condition; the need for ventilatory support and neonatal survival rate. For it, preterm lambs, born with 135 days of gestation, were randomly allocated into three groups: prenatal maternal corticosteroid therapy (CORT PRE; n = 8), postnatal corticosteroid therapy (CORT POST; n = 9) and control (CONT; n = 5). The steroid therapy was performed with betamethasone in a single dose of 0.5 mg/ kg, by intramuscular route of administration, at 133 days of pregnancy our after 10 minutes from the birth in the groups CORT PRÉ and CORT PÓS, respectively. The labor was induced with aglepristone administrated 49 hours prior to the estimated date of birth. Newborns were assessed by Apgar score, general medical condition (heart rate, respiratory rate, muscle tone and reflex irritability), body temperature, blood gas analysis, blood glucose, blood lactate concentration, serum concentrations of antioxidant enzymes (superoxide dismutase - SOD and glutathione peroxidase - GPx) and marker of oxidative stress (TBARS). The assessments were performed in 10 moments during the three days from delivery. For ventilated newborns, we assessed the needed time (in minutes) between birth and the beginning of ventilatory protocol, as well as length of stay on ventilatory support. Data were analyzed using parametric and nonparametric tests, with 95% of significance level. The variables were assessed from Spearman correlation test. As results, we noted better condition of vitality and muscle tone in newborns treated when compared with control group. Regarding cardiogenic values, antenatal betamethasone resulted in bradycardic effect, while its postnatal administration was related with tachycardia. Both results of respiratory and body temperature rates were significantly higher in newborns treated compared to the control. All lambs born whith bradycardia and bradypnea, reached normal values from 10 minutes of life. Hyperglycemia was observed in the treated groups, with statistically higher values in CORT PÓS group. The lactate value was statistically higher in CORT PÓST group compared to the control. Concerning the components of the acid-base balance, the CORT PRÉ showed significantly higher values of bicarbonate, while lower pressures of CO2 were observed from 60 minutes, although there were no differences in pH and BE values. The treatments did not determine changes in PO2 and SO2 values. However, the different protocols of steroid therapy influenced on neonatal blood profile, with significantly higher hematocrit values in CORT POST group, followed by CORT PRÉ. We also observed influence of postnatal treatment in SOD values as well as positive correlation between SOD and the hematocrit and hemoglobin values. Comparing the percentage of lambs submitted to mechanical ventilation, there were most ventilated neonates in the control group. Lower ventilation time was observed in the CORT PRÉ group. Then we conclude that, the postnatal or antenatal steroids improve neonatal clinical condition (vitality, muscle tone and vital functions), lung function (gas exchange and compensation to acid-base imbalances) and metabolic activity (glycemic control). The postnatal treatment increased the activity of SOD by reducing the risks of pulmonary damage. Moreover, treatment with postnatal betamethasone or prenatal maternal reduces the need for mechanical ventilation in extremely preterm lambs

Made available in DSpace on 2017-07-10T17:47:57Z (GMT). No. of bitstreams: 1 Paula_Regina_Hermes.pdf: 411163 bytes, checksum: 66a49a7572de84a16414d0ba8c07261f (MD5) Previous issue date: 2013-09-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Aiming to assess the different levels of feed restriction for a compensatory gain on the performance, and sheep carcass characteristics, were used twenty four males, Santa Inês breed, allocated in fully randomized design, in which were investigated four levels of feed restriction (0, 20, 40 and 60%). Eighteen animals with average body weight of 20.3 Kg were submitted during 64 days to 20, 40 and 60% of feed restriction based on the consumption of the animals fed ad libtum (0% restriction) and later all animals were fed unrestrainedly for a second period of 64 days. Regression analysis was used to study the levels of feed restriction, when significant differences were detected in the analysis of variance. The feed restriction promoted a negative effect under the performance of the animals, in a way that the increase in the feed restriction level resulted in lower weight of animals at the end of the first period. In the feedback period the animals submitted to previous feed restriction presented similar daily dry matter intake, however better food conversion and feed efficiency, reflecting a higher daily weight gain, a fact which characterized the compensatory gain. Nevertheless, the feedback period was not sufficient for animals to present the same final weight as animals fed unrestrainedly during all the experiment, resulting a partial compensatory gain. The negative linear effect of restrictive diets under the animals final performance reflected in smaller values of body weight at rise, body weight at slaughter, warm carcass weight, empty carcass weight, cool carcass weight, and commercial meat cuts weight. The management of feed restriction for 64 days followed by ad libtum feed for a similar period causes negative effects on the performance of sheep in termination, resulting in losses in carcass weights and commercial meat cuts weight / Com o objetivo de avaliar diferentes níveis de restrição alimentar para ganho compensatório sobre o desempenho e as características de carcaça, foram utilizados 24 ovinos machos, da raça Santa Inês, alocados em delineamento inteiramente casualizado, onde foram estudados quatro níveis de restrição alimentar (0, 20, 40 e 60%). Dezoito animais com peso corporal médio de 20,3 kg foram submetidos durante 64 dias a 20, 40 e 60% de restrição alimentar em função do consumo dos animais alimentados ad libtum (0% restrição) e posteriormente todos os animais receberam alimentação à vontade por um segundo período de 64 dias. A análise de regressão foi utilizada para estudo dos níveis de restrição alimentar, quando detectadas diferenças significativas na análise de variância. A restrição alimentar promoveu efeito negativo sob o desempenho dos animais, de forma que o aumento do nível de restrição alimentar resultou em menor peso dos animais ao fim do primeiro período. No período de realimentação os animais submetidos à restrição alimentar anterior apresentaram semelhante consumo diário de matéria seca, entretanto melhor conversão alimentar e eficiência alimentar, refletindo em maior ganho de peso diário, fato este que caracterizou o ganho compensatório. Entretanto, o período de realimentação não foi suficiente para que os animais apresentassem os mesmos pesos finais que os animais alimentados à vontade durante todo o experimento, ocasionando ganho compensatório parcial. O efeito linear negativo dos regimes alimentares restritivos sob o desempenho final dos animais refletiu nos menores valores de peso corporal a origem, peso corporal de abate, peso de carcaça quente, peso de carcaça vazia, peso de carcaça fria e peso dos cortes comerciais. O manejo de restrição alimentar por 64 dias seguido de alimentação ad libtum por igual período causa efeitos negativos sobre o desempenho de cordeiros em terminação, ocasionando prejuízos no pesos de carcaça e pesos de cortes comerciais

Made available in DSpace on 2014-08-20T14:38:50Z (GMT). No. of bitstreams: 1 Tese_Clovis_Jose_Cardoso_de_Avila.pdf: 2746145 bytes, checksum: 62c7ab08eaaea53ed524a1d6314c3fd7 (MD5) Previous issue date: 2010-05-30 / The study was conducted in two distinct properties located in the region of Serra do Sudeste, Rio Grande do Sul, Brazil: counties of, Pedras Altas and Arroio Grande. The overall objective was to evaluate the possibilities of increased production of lamb meat quality by using alternative methods to increase productivity and the effect of three finishing systems and sex on growth and development of lambs. In the first study 74 sheep were used from the cross of Corriedale and Texel rams and three Poll Dorset breed. The animals were kept on ryegrass pasture and native grassland, and supplemented daily with a mixture of soybean hulls and corn in amounts determined according to the availability of forage and the needs of each category. The sheep were subjected to the male effect and exposed to artificial reduction of photoperiod and later synchronization, needed in times (December and August). Fixed mating season was and response to the rate of estrus. The rates of estrus observed in this study show no significant difference (P <0.05) between the periods studied in the first service. However following the a second mating of sheep, differences were observed, where at the time of June a lower rate of expression of estrus (80%) was obtained. It is concluded that the use of management with the control of photoperiod in times of mating unconventional causes estrus rates over time traditionally used. In the second stage were used 90 x Corriedale lambs Texel, and 45 non-castrated males and 45 females divided into three finishing systems lamb with mother grazing (CMPN); lamb weaned, grazing (CDPN), lambs weaned, grazing supplemented with soybean hulls to 1% body weight (CDPNS). The slaughter criterion was 2.0 to 3.0 corporal condition. The effect of sex was higher in males for Initial Weight, GPTotal, GmdTotal, weight at 100 days, GP 70-100, Gmd70-100, weight at 120 days, anterior height, back Height, body weight, HCW, skin, full green guts, legs, head, heart, lung + trachea., liver vesicle., bladder and kidneys, for the female sex was higher for internal fat and fat-renal pelvic in percentages. The treatment effect was manifested to GmdTotal, GP 70-100, Gmd70-100, GP 100-120, 100-120 ADG, heart, internal fat and pelvic renal fat and percentages for HCW and full green guts. / O estudo foi realizado em duas propriedades distintas situadas na região da Serra do Sudeste, no Rio Grande do Sul, no município de Pedras Altas e no município de Arroio Grande. O objetivo geral foi avaliar as possibilidades de aumento de produção de carne ovina de qualidade, utilizando métodos alternativos de incremento de produtividade e o efeito de três sistemas de terminação e sexo no crescimento e desenvolvimento de cordeiros. Na primeira parte foram utilizando 74 ovelhas provenientes do cruzamento das raças Corriedale e Texel e três carneiros da raça Poll Dorset. Os animais foram mantidos em pastagem de azevém e campo nativo, além de serem suplementadas diariamente com uma mistura de casquinha de soja e milho em quantidades determinadas conforme a disponibilidade de forrageira e as necessidades de cada categoria. As ovelhas foram submetidas ao efeito macho e expostas à redução artificial do fotoperíodo e posterior sincronização, nas épocas necessárias (dezembro e agosto). Foi utilizado como efeito fixo a época de acasalamento e como variável resposta a taxa de estro. As taxas de estro observadas neste estudo mostram que não houve diferença significativa (P<0,05) entre as épocas estudadas no primeiro serviço, no entanto após o repasse dos carneiros, foi observada diferença, onde na época de junho foi obtida menor taxa de manifestação de estro (80%). Conclui-se que o uso do manejo com o controle do fotoperíodo nas épocas de acasalamento não convencionais provoca taxas de estro superiores à época tradicionalmente utilizada. No segundo momento foram utilizados 90 cordeiros Texel x Corriedale , sendo 45 machos não castrados e 45 fêmeas separados em três sistemas de terminação cordeiro com a mãe, mantidos em pastagem (CMPN); cordeiro desmamado, mantidos em pastagem (CDPN); cordeiro desmamado, mantidos em pastagem com suplementação com casca do grão de soja a 1% peso corporal (CDPNS). O critério de abate foi à condição corporal 2,0 - 3,0. O efeito do sexo se superior nos machos para Peso Inicial, GPTotal, GmdTotal, Peso 100 dias, GP70-100, Gmd70-100, Peso 120 dias, Altura do Anterior, Altura do Posterior, Peso corporal, PCQ, Pele, Vísceras Verdes Cheias, Patas, Cabeça, Coração, Pulmão+traq., Fígado+Vesic., Bexiga e Rins, para as fêmeas o sexo se manifestou superior para gordura interna e Gordura Pélvico-renal em valores percentuais. O efeito do tratamento se manifestou para GmdTotal, GP70-100, Gmd70-100, GP 100-120, Gmd 100-120, Coração, Gordura interna e Gordura Pélvico-renal e para valores percentuais para PCQ e V.Verdes Cheias.

Made available in DSpace on 2014-08-20T14:38:51Z (GMT). No. of bitstreams: 1 Dissertacao_Raquel_Klumb_Arnoni.pdf: 228099 bytes, checksum: 786bcc20135c829be6d147fb7faa5649 (MD5) Previous issue date: 2010-03-08 / Effect of sex on tissue composition was evaluated, as well as instrumental and subjective evaluation of meat from cross-bred Lacaune X Texel lambs grown in improved native pasture and supplemented with ration and hay. Twenty two lambs (11 females and 11 males), were used born in September 2007 and slaughtered in January 2008.Slaughtering criterion for lambs was based on body condition (ranking from 2.5 to 3.5). After slaughter the carcasses were placed in cold room with forced air and temperature within ± 1°C. Subjective evaluations of texture, marbling and color of meat were performed. Other instrumental objective measures were made, such as the ability to retain water, as measured by the method of loss by pressure, and the color, evaluated by two methods: physicochemical and using a colorimeter obtained through the system CIELAB. The pH and temperature of the Longissimus dorsi muscle were measured at 0 hours, 24 hours and 48 hours post-mortem. For the analysis of tissue composition the separation of the following tissues was performed: subcutaneous fat, intermuscular fat, other, muscle and bone. The experimental design was completely randomized, with two treatments and eleven replications. The data were subjected to analysis of variance. Males and females from crossbreeding Lacaune X Texel present the same meat quality for subjective and instrumental characteristics. / Foi estudado o efeito do sexo sobre a composição tecidual e avaliação subjetiva e instrumental da carne de cordeiros cruza Lacaune X Texel terminados em campo nativo melhorado e suplementados com ração e feno. Foram utilizados 22 cordeiros (11 fêmeas e 11 machos), nascidos em setembro de 2007 e abatidos em janeiro de 2008. Para o abate dos cordeiros foi utilizado como critério a condição corporal de 2,5 a 3,5 numa escala de 1 a 5. Após os cordeiros serem abatidos as carcaças foram acondicionadas em câmara fria, com ar forçado, a temperatura de ±10C. Foram feitas avaliações subjetivas de textura, marmoreio e cor. Medidas objetivas instrumentais como a capacidade de retenção de água, sendo medida através do método de perda por pressão e a cor foi avaliada através de dois métodos: Físico-químico e utilizando colorímetro, obtendo através do sistema CIELAB. O pH e a temperatura do músculo Longissimus dorsi foram medidos nos momentos 0 h, 24 h e 48 h pós-mortem. Para a análise da composição tecidual da paleta e da perna foi realizada a dissecação havendo a separação dos seguintes tecidos: gordura subcutânea, gordura intermuscular, outros, músculo e osso. O delineamento experimental utilizado foi o inteiramente casualizado, com dois tratamentos e onze repetições sendo os dados submetidos à análise de variância. Cordeiros machos não castrados e fêmeas provenientes do cruzamento Lacaune X Texel apresentaram qualidade de carne semelhante quanto às características subjetivas e instrumentais.

Os efeitos do fornecimento de dietas contendo glicerina bruta foram avaliados em quatro experimentos com ovinos de diferentes categorias. Experimento 1: Quarenta cordeiros foram usados para avaliar os efeitos da inclusão de glicerina bruta sobre o desempenho, as características de carcaça e da carne e a concentração de enzimas hepáticas. As rações experimentais foram isonitrogenadas, sendo que o ajuste proteico foi realizado pela inclusão de ureia e farelo de soja. Os teores de inclusão de glicerina bruta foram: 0, 5, 10 ou 15% na MS. A adição de glicerina bruta causou efeito quadrático no CMS, CFDN, CPB, GMD e peso final. A inclusão de glicerina causou efeito quadrático para peso corporal ao abate, PCQ e PCF. Foi observado efeito quadrático para os ácidos graxos mirístico, palmítico, palmitoleico, linoleico e rumênico. A glicerina bruta demonstrou ser um bom substituto do milho em dietas com alto teor de concentrado, melhorando o desempenho e as características da carcaça dos animais quando incluída até 10% na MS. Experimento 2: Cinquenta cordeiros(as) foram usados para avaliar os efeitos da inclusão de glicerina bruta em rações com alta proporção de concentrado, sobre o desempenho, características de carcaça e parâmetros enzimáticos. As rações experimentais foram isonitrogenadas, sendo o ajuste proteico realizado pela inclusão de farelo de soja. Os teores de inclusão de glicerina bruta foram: 0, 5, 10, 15 e 20% na MS. A inclusão de glicerina bruta não afetou as variáveis de desempenho analisadas. Houve apenas efeito linear para o CMM. A glicerina bruta pode substituir o milho em até 20%, mantendo o desempenho dos animais e as características de carcaça. Experimento 3: Cinco borregos canulados no rúmen foram utilizados para avaliar os efeitos da glicerina bruta sobre os parâmetros ruminais, a digestibilidade das dietas e o metabolismo de nitrogênio. As dietas foram isonitrogenadas e os teores de inclusão de glicerina bruta foram: 0, 5, 10, 15 ou 20% na MS. Houve redução linear na ingestão de FDN e aumento linear na ingestão de MM. Houve efeito linear crescente para a digestibilidade da MS e MO. A inclusão de glicerina bruta causou redução linear no acetato, relação C2:C3, AGCC total, e aumento linear no pH ruminal. A glicerina bruta pode substituir até 20% do milho em dietas de borregos, melhorando a digestibilidade da MS e MO. Experimento 4: Cento e dezoito ovelhas com 90 dias de prenhez foram utilizadas para avaliar a inclusão de glicerina bruta em dietas de gestação e lactação. Os teores de inclusão foram 0 ou 10%. Da segunda a oitava semana foi mensurado o CMS e produção de leite das ovelhas e a ingestão de concentrado inicial dos cordeiros. A inclusão de glicerina bruta aumentou o CMM e reduziu a porcentagem de gordura no leite. A adição da glicerina bruta na dieta das ovelhas diminuiu a concentração sérica de AGNE. A inclusão de 10% de glicerina bruta na dieta de ovelhas durante a gestação e lactação não prejudica o desempenho dos animais e reduz a possibilidade de ocorrência de toxemia da gestação. / The effects of feeding diets with crude glycerin were evaluated in 4 trials using different categories of sheep. Experiment 1: Forty Santa Inês ram lambs were used to determine the effects of partial replacement of corn by crude glycerin on growth, hepatic enzymes, carcass and meat characteristics of lambs fed high-concentrate diets. The diets were isonitrogenous and the protein was adjusted by increasing urea and soybean meal. Increasing levels of crude glycerin were: 0, 5, 10 or 15%. There was quadratic effect for DMI, NDFI, CPI. ADG and final weight. There was a quadratic effect for slaughter BW and dressing percentage, but no difference on longissimus muscle area, backfat thickness and body wall thickness. There was quadratic effect for myristic, palmitic, palmitoleic, linoleic and rumenic acid. Crude glycerin is a good substitute of corn in high-concentrate diets, improving performance and carcass characteristics when included until 10% of the diet DM. Experiment 2: Fifty lambs were used to determine the effects of partial replacement of corn by crude glycerin on growth, carcass characteristics and hepatic enzymes of lambs fed high concentrate diets. The diets were isonitrogenous and the protein adjusted was performed with increased soybean meal. Increasing levels of crude glycerin were: 0, 5, 10, 15 or 20%. There was an increased in mineral matter intake. Crude glycerin can be used as a substitute for corn in high concentrate diets of ram lambs without affecting performance and carcass characteristics. Experiment 3: Five Santa Inês ram lambs, cannulated in the rumen, were used to determine the effects of using crude glycerin on ruminal constituents, diet digestibility and nitrogen metabolism. The diets were isonitrogenous and crude glycerin was included in the ration at 0%, 5%, 10%, 15% or 20% in the DM. There was linear decreased on NDF intake and a linear increase in ash intake. Feeding crude glycerin increased DM and OM digestibility. Crude glycerin decreased acetate, acetate:propionate ratio, total SCFA and showed a linear increase on pH. Replacing corn by crude glycerin up to 20% of dietary DM increased DM and OM digestibility, maintained propionate and decreased acetate and total SCFA. When soybean meal was used to adjust the diet protein level, there were no changes on nitrogen metabolism. Experiment 4: One hundred and eighteen 90 d pregnant ewes were used to determine the effects of feeding crude glycerin on performance, NEFA concentration and lamb growth. Diets were isonitrogenous and crude glycerin levels were zero or 10%. From the second until de eighth week of lactation DM intake of the ewes and starter of the lambs were measured. There was an increase on ash intake for the glycerin fed ewes. There was a decrease in milk fat percentage. Crude glycerin fed ewes showed a decrease on blood NEFA. The inclusion of 10% of crude glycerin in the diets of sheep during pregnancy and lactation had no detrimental effect on performance of ewes and lambs. Using 10% of crude glycerin decreases the chances of pregnancy toxemia in ewes.

The aim of this study was to evaluate the Small Ruminant Nutrition System (SRNS) model’s performance predictions for lambs under South African conditions using growth and body composition data of early- (Dorper) and late-maturing (South African Mutton Merino), indigenous sheep breeds. The Cornell Net Carbohydrate and Protein System (CNCPS) biological model has consistently been modified to include recent information. This has led to the development of the SRNS model, but up to now the SRNS model has only been validated with European sheep breeds under European conditions. Thirty two Dorper, 16 male and 16 female lambs, and 36 South African Mutton Merino, 18 male and 18 female lambs, were fed a grower diet for the experimental period of 60 days. Three groups of lambs of each breed were slaughtered as the lambs reached pre-determined target weights. The first group of 24 animals (slaughter group 1) was slaughtered at the onset of the experiment at a live weight of 20 kg. With the second group (slaughter group 2) the South African Mutton Merinos were slaughtered at an average weight of 35 kg and the Dorpers at an average weight of 30 kg. The last group (slaughter group 3) had an average weight of 50 kg for the South African Mutton Merinos and 40 kg for the Dorpers at slaughter. Using the data from this trial, predictions of the average daily gain (ADG), feed intake (DMI), empty body gain and the composition of the empty body gain were used to evaluate the model. The animals were divided into three slaughter groups, based on growth stage, for the determination of body composition data. Energy value of gain (EVG), fat and protein content on a shrunk and empty body weight basis were compared with the corresponding values predicted by the SRNS. Growth composition of the lambs was determined by dividing them into two growth periods. Average daily gain and DMI were evaluated in the experiment, and results compared to the mean ADG and DMI predictions obtained from the SNRS model. Two different equations were compared to estimate EVG and two sets of coefficients were also compared for the EVG. Five different equations were compared to estimate the efficiency of conversion of metabolisable energy (ME) to net energy (NE) for gain, kg. The correction factor to adjust for the increase in the size of the visceral organs as nutrient intake increases and the coefficient for the effect of gender on maintenance requirements were tested for relevance of use in the SRNS. Overall, based on these evaluations it appears that the original SRNS model gave the best predictions when compared to any of the modifications tested. With regards to ADG the model over-predicts the requirements of the lambs in the early growth stage and under-predicts the requirements of the lambs in the later growth stage. The DMI predictions that were made using the original SRNS were accurate. The evaluation of the SNRS predictions in relation to the composition of gain indicated that this model over-predicted both the fat and the protein content of gain. The predictions were accurate, however the precision was low. The low precision was probably due to the lack of variation in the measured range of fat and protein content of gain. Before field application further studies and adjustments to the SRNS model is required, especially with regard to predictions on the fat and protein content of gain and over or under predictions of ADG during different growth stages of Dorper and South African Mutton Merino lambs. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted

The muscle hypertrophy of lambs expressing the Callipyge phenotype is possibly linked to characteristics of their muscle satellite cells. Therefore, characteristics (proliferation, fusion %, and protein accretion) of cultured satellite cells isolated from the longissimus muscle of Callipyge (n = 3) and normal (n = 3) lambs were compared in this study. In the first experiment, we tested whether or not the lll proliferation rates differ for satellite cells isolated from Callipyge or normal sheep when cultured in the presence of different serum types (horse, normal lamb, or Callipyge lamb). The average population doubling time (PDT, h) during log phase growth was calculated for cells from each animal grown in each serum type. Population doubling time was not affected (P > .1) by the interaction of satellite cell type with serum type, or by satellite cell type. Unexpectedly, PDT was longer (P < .05) for satellite cells grown in Callipyge serum (22 h) than for cells grown in normal sheep serum (20 h) or horse serum (18 h). These results suggest that muscle hypertrophy of Callipyge lambs is not linked to intrinsic differences in satellite cell proliferation, although hypertrophy may be associated with a decreased proliferation induced by a factor in Callipyge serum. In the second experiment, we tested whether cell fusion, or protein accretion differ for cultured satellite cells isolated from Callipyge or normal sheep. DNA and protein were determined at 24, 48, 72, and 96 h after satellite cell cultures were induced to differentiate. Fusion percentage was determined in a Giemsa stained plate after 72 h in differentiation medium (Dulbecco's Modified Eagle Medium containing 1.5% of horse serum). Callipyge cultures tended (P = .14) to have higher fusion% than normal cultures exhibited, suggesting that muscle hypertrophy of Callipyge lambs may be linked to an increased tendency of satellite cells to fuse. Protein content (μg/well) and protein:DNA ratio (ng of protein/ng of DNA) were not affected by satellite cell type (P = .80 and P = .79, respectively). Thus, there was no evidence for a link between increased protein accretion and Callipyge hypertrophy.

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M.S.