Use of soybean lecithin in broiler chicken diets.

Abstract

Fat addition is a common practice in feed manufacturing in order to increase the energetic density of diets and provide essential nutrients to livestock animals. The availability of conventional energetic ingredients for broiler chicken diets may be compromised by a constant growing world-wide population and the current tendency to use vegetable oils for biodiesel production. In this context, soybean lecithin (L), as a co-product obtained during soybean oil (S) refining process, may represent an economical and alternative energy source due to its high content in phospholipids, triacylglycerols, free fatty acids (FFA), phosphorus, choline and antioxidant compounds. Therefore, the global aim of the present thesis was to investigate the potential use of L, as energy source for broiler chicken diets. Several trials were performed with the aim to evaluate the inclusion of L as energy source in broiler feeding and study its influence on performance, energy utilization, fatty acid (FA) digestibility and the FA profile of the abdominal fat pad. A basal diet was supplemented at 3% with either S or acid oil (A) and increasing amounts of L (crude and high in FFA for Chapter Three and Four, respectively) were included in replacement (1%, 2% and 3%). In relation to S replacement, despite no effects were observed on performance parameters, results from the digestibility balances indicated that S replacement by L, in starter broiler chickens, lowered FA digestibility and the apparent metabolizable energy content of the diets. However, in grower-finisher broiler chickens, partial replacements up to a 2%, did not modify performance, and the utilization of energy and total FA. Regarding the replacement of A by L, in starter and grower-finisher broiler chicken diets, it was observed that blending both co-products have resulted in improvements on energy and nutrient utilizations. Finally, the FA profile of the adipose tissue was a clear reflect of the FA composition of the added fats, and S replacement by L produced slight changes on the FA profile of the abdominal fat pad. The last experiment (Chapter Five) consisted in a field trial under experimental conditions with the main objective to study, in grower and finisher broiler chicken diets, different levels of L inclusion in replacement of S and its effects on growth performance. In addition, ileal absorption of FA, FA profile of the abdominal fat pad and gut health markers were assessed. Soybean oil total replacement by L (2% of inclusion), in diets that also contained palm and A (3.25% and 4.5% of total added fats for grower and finisher diets, respectively), did not modify performance parameters, total FA ileal digestibility and jejunal morphology. On the other hand, a reduction on the digestibility of the polyunsaturated FA and an increase on Lactobacillus spp. counts at the jejunum were linked to total replacement; however, with no significant consequences on growth efficiency. Slight modifications were observed on the saturation degree of the abdominal fat pad, associated to the FA profile of the different added fats. Taking all the results into account, it was evidenced that L is a suitable energetic ingredient for grower and finisher broiler chicken diets due to it was observed that S partial replacements up to a 2% by L do not alter growth performance and the utilization of energy and FA. Besides, the blending of L and A results an interesting option, for adult broiler diets, due the existence of positive interactions on energy and FA utilization.

Date of Award	4 Jul 2019
Original language	English
Supervisor	Ana Cristina Barroeta Lajusticia (Tutor) & Lorena Castillejos Velázquez (Director)