The role of carbohydrates when applying different nutritional interventions to nursery and growing pigs

Abstract

<p>Carbohydrates represent the largest components of swine diets in the U.S. due to the different chemical and physical characteristics among sources; carbohydrates can exert different effects in the gastrointestinal tract of pigs. The primary purpose of this dissertation was to improve our understanding of the role of simple and complex carbohydrates on various nutritional interventions for nursery and growing pigs. To achieve this objective 5 experiments were conducted. A set of three experiments were designed to determine the effect of a prototype Lactobacillus acidophilus fermentation product (FP). The first experiment evaluated the FP with and without dietary antibiotics on growth performance. Second, a similar experiment was performed to determine the effect of the FP and lactose (LA) level on growth performance in an antibiotic-free diet scenario. A more mechanistic experiment was conducted to determine the effects of LA and the FP, on diet digestibility, N balance and intestinal function of weaned pigs. A set of- two experiments were designed to investigate the role of insoluble in two scenarios. The first experiment evaluated the effect of insoluble fiber on the efficacy of the phytase enzyme in nursery pigs when fed diets limiting in P content. The second was designed to determine if the impact of increasing insoluble fiber level on the digestibility of energy and nutrients- differs when diets are adjusted to constant nutrient (CN) or to constant ingredient composition (CI). Results of Exp 1 supported the positive role of dietary antibiotics on the growth performance of nursery pigs. However, the addition of FP or increasing the level of LA (from 7.5 to 15%) were not effective strategies to improve these growth variables (Exp 1 and Exp 2). Results of Exp 3 showed that LA benefits the weaned pig by improving nutrient utilization rather than by improving gut function and structure. Results also showed a little benefit of using FP alone or in combination with LA and that there were no additive effects between the two (LA and FP), at least under the conditions of this study. Results of Exp 4 clearly showed that the efficacy of</p> <p>phytase to release P from phytate is not impaired by insoluble fiber. Results of Exp 5 showed that increasing the insoluble fiber level in the form of DDGS decreased the digestibility of most dietary components. Results also showed that the use of the CI method for formulating diets resulted in a lower digestibility of insoluble fiber compared with diets formulated using the CN method. This demonstrated the bias that can be introduced into this type of experiment by the formulation method.</p>