Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.5/2040
Título: Efeito da suplementação enzimática em fases específicas do crescimento dos frangos ao nivel da performance produtiva e dimensões do sistema gastrointestinal
Autor: Ferreira, Ana Patricia Alves
Orientador: Lordelo, Maria Madalena dos Santos
Palavras-chave: broilers
barley
performance
gastrointestinal traits
frango
cevada
performance
sistema gastrointestinal
Data de Defesa: 2009
Resumo: Animal nutrition grew to improve productive animal performance among others goals. Several feedstuffs have been used in poultry production and corn has been the major source of energy. Because of economics and productive changes, especially induced by the use of cereals in other industries, there was the need to use others ingredients, such as barley. Besides, an increased stability of the grain and it´s widely distribute around the world, barley has a lower market price. Barley has been suggested to constitute a good substitute of other cereals in avian nutrition. One of the problems in the use of this cereal is the content and localization of antinutritive factors. They are incrusted in cellular wall of small cells that surround the starch grains and difficult the contact of digestive enzymes with this contents. In barley, the major antinutritive factor known are β-glucans. β-glucans cause larges morphological modifications and decrease of productive performance when present in broiler diets. The negative effects of β-glucans are connected with an increased viscosity of the gastrointestinal contents. The increase in viscosity results higher solubility of β-glucans with water molecules. Viscosity can be a major problem especially in young chicks. Young chicks have an immature digestive and enzyme capacity and because of that they are unable to contradict some effects caused by the viscous diets. To face this problem, enzyme supplementation evolved and created more efficient enzyme complexes. The development of the enzyme industry allowed the use of more grains species, such as barley or rye, and an improvement in the productive performance of chicks. The use of enzymes increases productive performance of broilers especially during the first weeks of age but these results have been achieved in previous studies where enzyme was supplemented throughout the entire broiler´s life. The objective of this work was to study the effect of enzymatic supplementation of a barleybased diet on the performance and gastrointestinal traits during specific stages of broilers development. For this study, 160 one-day-old young chicks, which were assigned randomly in groups of four birds over 40 pens were used. The animals were subjected to five different treatments: B0 (diet without enzymatic supplementation), B1 (diet with enzyme supplementation in 1st week), B2 (diet with enzyme supplementation in 1st and 2nd week), B3 (diet with enzyme supplementation in 1st, 2nd and 3rd week) and B4 (diet with enzyme supplementation in 1st, 2nd,3rd and 4th week) with 8 replicates each. Feed and water were available ad libitium. Each animal was weighed in the end of each week throughout 4 weeks. At the end of the trial, one animal per pen was killed by lethal injection. Weight of liver, crop, gizzard and weight and length of the portions of intestinal tract were measured. Enzymatic activity and viscosity were also analysed. Results of performance, feed conversion, weight and weight gains showed that enzyme supplementation was more efficient in animals fed diet B1 and diet B2, respectively. There were no differences in the relative weight of liver, crop and gizzard. We expected that enzyme supplementation lead to a decrease in intestinal length but it was not verified in this study. The major differences were in relative weight of jejunum and ileum that was lower in animal fed diet B4. Ileal viscosity was lower and enzyme activity was higher in animals fed diet B4 because of the long supplementation period of this diet. Taken together the data suggest that enzyme supplementation leads to better performance, weight gains and feed conversion, in the first weeks of age of birds. Enzyme supplementation in the early stages of development is beneficial to young chicks with immature digestive and enzyme capacity. The results suggest that is unnecessary to supplement broiler diets with enzymes throughout their entire life.---------------------------------------Estudou-se durante 4 semanas os efeitos da suplementação enzimática de dietas à base de cevada durante fases específicas do crescimento de frangos ao nível da performance e dimensões dos diversos compartimentos do sistema gastrointestinal. Cento e sessenta pintos foram divididos em grupos de 4 por 40 gaiolas e submetidos a 5 tratamentos: B0 (dieta sem enzima), B1 (dieta com enzima na 1ª semana), B2 (dieta com enzima na 1ª e 2ª semana), B3 (dieta com enzima na 1ª, 2ª e 3ª semana) e B4 (dieta com enzima nas 4 semanas) com 8 réplicas cada. Forneceu-se alimento e água ad libitum. No final do ensaio, abateu-se 1 animal por gaiola. Os frangos sujeitos à dieta B1 apresentaram índices de conversão idênticos aos animais das dietas B2, B3 e B4. Os frangos com a dieta B2 apresentaram pesos vivos e aumentos de peso semelhantes aos animais das dietas B3 e B4. Os pesos relativos do papo, moela e fígado dos animais foram semelhantes. A dieta B4 diminuiu a viscosidade no duodeno+jejuno, ileo e o peso relativo do jejuno e ileo. A dieta B4 apresentou maior actividade enzimática. Concluiu-se que a suplementação enzimática na 1ª e 2ª semana bastou para alcançar performances equivalentes aos animais suplementados nas 4 semanas.
Descrição: Mestrado em Engenharia Zootécnica - Produção Animal - Instituto Superior de Agronomia / Faculdade de Medicina Veterinária
URI: http://hdl.handle.net/10400.5/2040
Aparece nas colecções:BISA - Dissertações de Mestrado / Master Thesis

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