Made available in DSpace on 2014-06-11T19:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-10-27Bitstream added on 2014-06-13T19:46:39Z : No. of bitstreams: 1 duarte_cra_dr_botib.pdf: 306887 bytes, checksum: 17069ee89c8d10234795eabd667db6a0 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A restrição alimentar é comumente utilizada na produção de frangos para melhorar o desempenho e qualidade da carcaça e prevenir problemas reprodutivos, metabólicos e esqueléticos. Esta prática, no entanto, afeta diferentes sistemas do organismo, incluindo o trato gastrointestinal. Os efeitos da restrição alimentar aplicada durante a primeira ou segunda semana de vida em frangos sobre a morfologia do trato gastrointestinal são bem conhecidos. No entanto pouco se conhece sobre seus efeitos nos processos de digestão e absorção de nutrientes. Além disso, não há relatos na literatura sobre os efeitos da restrição alimentar e realimentação em outras fases do desenvolvimento de frangos. Assim, este estudo investigou os efeitos da restrição alimentar e da realimentação sobre o trato gastrointestinal de frangos nas fases inicial (7 dias de idade) e final (35 de idade) do desenvolvimento. Para tanto, utilizou-se 4 grupos experimentais: C7: alimentado ad libitum durante 7 dias, R: 70% restrito durante 7 dias, C10: alimentado ad libitum durante 10 dias e RF: 70% restrito durante 7 dias e realimentado por 3 dias. Ao final dos períodos de restrição e de realimentação os animais foram sacrificados e os seguintes parâmetros foram analisados: peso dos órgãos do trato gastrointestinal, atividade de enzimas pancreáticas e intestinais, expressão gênica de enzimas e de transportadores de nutrientes, quantidade da proteína SGLT1 (cotransportador Na+/glicose) e de captação de glicose através da membrana apical pelo cotransportador SGLT1. Os resultados mostraram que o peso corporal de frangos restritos durante a fase inicial foi mantido e que o de animais restritos na fase final apresentou pequena perda. No entanto, animais restritos apresentaram diminuição do peso dos órgãos do trato gastrointestinal e da atividade de enzimas pancreáticas e intestinais. A expressão... / Feed restriction is commonly used in chicken production to improve the performance and the carcass quality and to control reproductive, metabolic and skeletal disorders. However, this management affects different systems of the organism, including the gastrointestinal tract. The effects of feed restriction applied in the first or second week after hatching on the gastrointestinal morphology are well known, but there are few reports about their effects on the nutrient digestion and absorption. Moreover, there are not studies concerning the effects of feed restriction and realimentation in the other phases of chicken growth. Thus, this study investigated the effects of feed restriction and realimentation on the chicken gastrointestinal tract in the initial (7 days old) and final (35 days old) phase of growth. For this, the animals were divided into 4 experimental groups: C7: food ad libitum for 7 days, R: 70% food restriction for 7 days, C10: food ad libitum for 10 days and RF: 70 % food restriction for 7 days, followed by realimentation for 3 days. Animals were sacrificed in the end of each experimental period (7th and 10th days, according to the group) and the following parameters were evaluated: gastrointestinal organs weight, pancreatic and intestinal enzymes activities, gene expression of enzymes and nutrient transporters, abundance of Na+-D-glucose cotransporter (SGLT1) and D-glucose uptake through the brushborder membrane by SGLT1. The results showed that the younger feed-restricted chickens maintained the body weight and that the older feed-restricted chickens slightly decreased the body weight. However, feed-restricted animals decreased the gastrointestinal organs weight and pancreatic and intestinal enzymes activities. The gene expression increased in the feed-restricted chickens whereas the SGLT1 abundance and activity decreased. After 3 days of reestablishment... (Complete abstract click electronic access below)

Thesis (M.Sc) (Agriculture)--University of Limpopo,2007. / Two experiments were carried out to evaluate the effects of feed restriction during the starter stage and lysine supplementation during realimentation on productivity and carcass characteristics of Ross 308 broiler chickens. In the first experiment, the effects of level and period of feed restriction during the starter period on subsequent productivity were evaluated. A 2 (male and female chickens) x 3 (feeding levels, ad libitum and 75% and 50% of ad libitum) x 3 (restriction periods of 5, 7 and 9 days), factorial arrangement in a Completely Randomized Design was used. The effects interactions were not included in the results because earlier analyses including all the interactions showed that they were not important. Level and period of feed restriction during the starter stage had an effect (P<0.05) on live weight of the chickens at 21 days of age. However, female and male chickens had similar live weights at 21 days of age. Chickens on 75% ad libitum feeding attained complete live weight compensation at the age of 42 days. However, chickens on 50% ad libitum feeding did not ‘catch-up’ with those on ad libitum feeding. Differences due to the period of feed restriction during the starter stage were maintained up to the age of 42 days. Male chickens had higher (P<0.05) live weights at 42 days of age. Abdominal fat pad was not affected (P>0.05) by level and period of feed restriction and sex of chickens at 42 days of age. The second experiment evaluated the effects of feed restriction during the starter stage (14 to 21 days) and levels of lysine supplementation during realimentation (21 to 42 days) on productivity and carcass characteristics of male and female chickens. Feed v restriction affected (P<0.05) live weight of chickens at the age of 21 days and males were heavier (P<0.05) than females at the same age. Chickens on 75% ad libitum feeding attained complete compensation in live weight while those on 50% ad libitum feeding did not. Lysine supplementation during realimentation had no effects (P>0.05) on live weight and carcass characteristics of the chickens at 42 days of age. Male chickens attained higher (P<0.05) live weights than female chickens at 42 days of age. / National Research Foundation

Orientador: Maria de Lourdes Mendes Vicentini Paulino / Banca: Alice Eiko Murakami / Banca: Denise Rangel da Silva Sartori / Banca: Daniela Felipe Pinheiro / Banca: Ana Carolina Luchiari / Resumo: A restrição alimentar é comumente utilizada na produção de frangos para melhorar o desempenho e qualidade da carcaça e prevenir problemas reprodutivos, metabólicos e esqueléticos. Esta prática, no entanto, afeta diferentes sistemas do organismo, incluindo o trato gastrointestinal. Os efeitos da restrição alimentar aplicada durante a primeira ou segunda semana de vida em frangos sobre a morfologia do trato gastrointestinal são bem conhecidos. No entanto pouco se conhece sobre seus efeitos nos processos de digestão e absorção de nutrientes. Além disso, não há relatos na literatura sobre os efeitos da restrição alimentar e realimentação em outras fases do desenvolvimento de frangos. Assim, este estudo investigou os efeitos da restrição alimentar e da realimentação sobre o trato gastrointestinal de frangos nas fases inicial (7 dias de idade) e final (35 de idade) do desenvolvimento. Para tanto, utilizou-se 4 grupos experimentais: C7: alimentado ad libitum durante 7 dias, R: 70% restrito durante 7 dias, C10: alimentado ad libitum durante 10 dias e RF: 70% restrito durante 7 dias e realimentado por 3 dias. Ao final dos períodos de restrição e de realimentação os animais foram sacrificados e os seguintes parâmetros foram analisados: peso dos órgãos do trato gastrointestinal, atividade de enzimas pancreáticas e intestinais, expressão gênica de enzimas e de transportadores de nutrientes, quantidade da proteína SGLT1 (cotransportador Na+/glicose) e de captação de glicose através da membrana apical pelo cotransportador SGLT1. Os resultados mostraram que o peso corporal de frangos restritos durante a fase inicial foi mantido e que o de animais restritos na fase final apresentou pequena perda. No entanto, animais restritos apresentaram diminuição do peso dos órgãos do trato gastrointestinal e da atividade de enzimas pancreáticas e intestinais. A expressão... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Feed restriction is commonly used in chicken production to improve the performance and the carcass quality and to control reproductive, metabolic and skeletal disorders. However, this management affects different systems of the organism, including the gastrointestinal tract. The effects of feed restriction applied in the first or second week after hatching on the gastrointestinal morphology are well known, but there are few reports about their effects on the nutrient digestion and absorption. Moreover, there are not studies concerning the effects of feed restriction and realimentation in the other phases of chicken growth. Thus, this study investigated the effects of feed restriction and realimentation on the chicken gastrointestinal tract in the initial (7 days old) and final (35 days old) phase of growth. For this, the animals were divided into 4 experimental groups: C7: food ad libitum for 7 days, R: 70% food restriction for 7 days, C10: food ad libitum for 10 days and RF: 70 % food restriction for 7 days, followed by realimentation for 3 days. Animals were sacrificed in the end of each experimental period (7th and 10th days, according to the group) and the following parameters were evaluated: gastrointestinal organs weight, pancreatic and intestinal enzymes activities, gene expression of enzymes and nutrient transporters, abundance of Na+-D-glucose cotransporter (SGLT1) and D-glucose uptake through the brushborder membrane by SGLT1. The results showed that the younger feed-restricted chickens maintained the body weight and that the older feed-restricted chickens slightly decreased the body weight. However, feed-restricted animals decreased the gastrointestinal organs weight and pancreatic and intestinal enzymes activities. The gene expression increased in the feed-restricted chickens whereas the SGLT1 abundance and activity decreased. After 3 days of reestablishment... (Complete abstract click electronic access below) / Doutor

Doctor of Philosophy / Department of Animal Sciences and Industry / Michael E. Dikeman / Sixty cull cows were utilized to investigate the effects of feeding a single or sequence of β-adrenergic agonists (β-AA) on performance, mRNA expression, carcass traits, economics, meat palatability, and ground beef color. Treatments included: 1) concentrate fed for 74 d (C); 2) concentrate fed for 49 d then supplemented with ractopamine-HCl for 25 d (RH); 3) concentrate fed for 51 d then supplemented with zilpaterol-HCl for 20 d (ZH); 4), concentrate fed for 26 d then supplemented with RH for 25 d followed by ZH for 20 d (RH + ZH). No differences existed among treatments for performance or carcass characteristics. However, cows supplemented with ZH (ZH and RH + ZH treatments) had increased LM areas (P = 0.18) compared to control and RH cows. Sequential feeding of RH followed by ZH had no influence on β2-adrenergic receptor (AR) mRNA expression. However, β2-AR mRNA was increased (P < 0.05) in the RH and ZH treatments when RH or ZH was supplemented during the last 20 to 25 d of feeding. Myosin heavy chain (MHC) Type IIa mRNA decreased (P < 0.05) from d 24 to 51 in all cows, while MHC-IIx increased (P < 0.05) in the ZH and RH + ZH treatments during ZH supplementation. No differences were observed in ground beef color shelf-life among treatments. Effects of β-AA supplementation on meat palatability varied among muscles. Infraspinatus steaks had improved (P < 0.05) WBSF values with β-AA supplementation. Psoas major steaks from the RH + ZH treatment were rated as more tender than steaks from all other treatments. Non-enhanced LM steaks from ZH supplemented cows had higher (P = 0.12) WBSF values along with decreased (P < 0.0001) percentages of degraded desmin compared to control and RH cows. Collagen solubility of the LM was increased with ZH supplementation compared to RH and control cows. Enhancement of steaks with 0.1 M calcium lactate improved LM tenderness of β-AA supplemented cows. Implanting and feeding cull cows for 74 d, regardless of β-AA supplementation, added value by transiting cows from a “cull” cow to “white” cow market.