Use of acid oils in broiler chicken diets
- Autores: Raquel Rodríguez Sánchez
- Directores de la Tesis: Alba Tres Oliver (dir. tes.), Ana Cristina Barroeta (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Gonzalo González Mateos (presid.), Gerardo Santomá Boixeda (secret.), Achille Schiavone (voc.)
- Programa de doctorado: Programa de Doctorado en Producción Animal por la Universidad Autónoma de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TESEO
- Resumen
The use of supplemental fats in feed formulation is a widespread practice for meeting both the energy and also essential fatty acid requirements. Food fat by-products, like those from the edible oil refining industry (acid oils), are an example of an economic alternative in comparison to conventional fats that can be revalorized as a feed fat ingredient.
Acid oils are rich in free fatty acids (FFA), and have similar fatty acid (FA) composition to their respective crude oils, but different molecular structures, which can affect their nutritional value. FFA have been negatively related to fat utilization, and it is well known that the saturation degree of dietary fat has a negative impact on fat utilization, as well as that the ability of chicks to digest and absorb dietary fat is poorly developed. Thus, the aim of the present thesis is to study in depth the digestion and absorption of fat in broiler chickens, and determine how the age of the chickens, the saturation degree and the FFA level of dietary fat affect these processes in order to raise recommendations on the use of oils with certain percentages of FFA in the diets with no negative repercussions on fat utilization. This is the first step to assess the use of acid oils in broiler chickens diets under up-to-date conditions.
The first trial (Chapter 3) was conducted in order to study the effect of the dietary fat saturation degree and age of the chickens (14 d and 35 d) on the fat digestion and absorption processes. For this purpose the dietary use of crude soybean oil and crude palm oil was studied, and the FA digestibility and lipid class composition were determined along the gastrointestinal tract (GIT; gizzard, duodenum, jejunum, and ileum), and excreta. The assessment of both the FA digestibility and lipid class content allowed for a better understanding of the fat digestion and absorption processes. It was seen that the FA absorption process was more affected than the hydrolysis process was by both the fat saturation degree and age of the chickens, being the jejunum the main place of FA absorption. However, the contribution of the ileum to FA absorption was also important, being the last GIT segment where FA absorption has been described. Furthermore, the utilization of unsaturated diets was higher than the utilization of saturated diets mainly due to a higher contribution of the ileum to saturated FA absorption, and the improvement on fat utilization in adult broiler chickens was due to an increase in the contribution of the jejunum to FA absorption.
The second trial (Chapters 4 and 5) was conducted to assess the effect of the dietary FFA level, fat saturation degree and age (14 d and 37 d) on fat digestion and absorption processes. Two crude oils and two fat by-products from the edible oil refining industry rich in FFA were used in order to produce eight dietary treatments with two different saturation degrees (soybean oil products as unsaturated fat source, and palm oil products as saturated fat source), and four levels of dietary FFA (5%, 15%, 35%, and 50%). FA digestibility and lipid class composition along the GIT, and excreta were determined. Concerning the dietary FFA level, the absorption process was more affected than the hydrolysis process was. The effect of dietary FFA level in the absorption process was found to be different depending on the saturation degree of dietary fat and age of the chicken. The results evinced that adult broiler chickens (37 d) were less affected by the dietary FFA level than young broiler chickens (14 d) were due to a more efficient FA absorption at the jejunum level. Thus, while at 14 d the diets with the highest dietary FFA level (50%) were related to lower fat utilization in comparison to the diets with the lowest dietary FFA level (5%), at 37 d this was less pronounced. Unsaturated diets were more affected by the dietary FFA level than saturated diets, and the suitable level of dietary FFA in grower-finisher diets was higher than in starter-broiler chicken diets. Regardless of the age, it was concluded that the FA profile of dietary fat has a bigger impact on fat utilization than the level of dietary FFA.
Taking all the results into account, it was evinced that the absorption process is more affected than the hydrolysis process is by the saturation degree and free fatty acid level of dietary fat, as well as by the age of the chicken. The greater utilization of unsaturated diets irrespective of the age was confirmed. Another interesting finding is that crude soybean oil could be partially replaced by acid soybean oil, being a good alternative fat source to be used in broiler chicken diets at least when the dietary FFA level does not exceed 15% and 35% in starter and grower-finisher diets, respectively. On the other hand, the saturated diet with 50% dietary FFA level did not differ from the saturated diet with the lowest dietary FFA level (5%), suggesting that acid palm oil (palm fatty acid distillate) could replace crude palm oil in grower-finisher diets, at least when the FFA level does not exceed 50% with no negative repercussions on fat utilization compared to the use of crude palm oil.
