The impact of insulin sensitivity and feeding behavior on nutrient utilization and body composition of finishing pigs

Authors: Salgado Romero, Héctor Hernando
Advisor: Létourneau Montminy, Marie-PierrePomar, Candido
Abstract: The current challenge in animal production is to maximize feed efficiency while minimizing production costs and environmental impacts. Feed efficiency is influenced by animal characteristics such as energy utilisation, which depends on the energy content of body weight gain, especially body lipids. However, there is important variation in body lipids and feed efficiency among pigs of the same genetic background. Therefore, understanding the mechanisms associated with this variation could help to improve animal production and/ormanipulate body composition in pigs. The aim of this thesis was to understand factors related with body composition variations and energy utilisation to improve the knowledge regarding the metabolic processes responsible for the observed variation between individual animals in their ability to use dietary nutrients for growth. Insulin sensitivity and feeding behavior were selected as candidates due to their influence in the dynamic of metabolic hormones such asinsulin that regulates lipid and protein synthesis. In this work, an original approach to describe feeding behavior accounting for limitations of conventional feeding parameters is proposed, and an in vivo technique to estimate de novo lipogenesis was adapted from radioactive to stable isotopes. The results of this work suggest that: 1) feeding behavior is not an important factor influencing energ yutilisation in pigs. However, the index to describe the irregularity of feed intake proposed in this work resulted ina suitable approach for describing individual feeding behavior patterns. This index integrates most of the information on feeding behavior obtained using several conventional feeding behavior variables and can be usedin studies regarding the effect of externals or animal factors on feeding behavior. 2) unlike feeding behavior, insulin sensitivity was strongly and negatively correlated with total body lipids and explained about 45 % of the total body lipids and protein variations among pigs. In addition, important associations among insulin sensitivity with metabolic processes were found at the genetic expression and synthesis level (e.g., lipid synthesis). This indicates that insulin sensitivity is an important factor determining the utilization of dietary energy and nutrients with implications for body composition in finishing pigs. This work helped to understand the role of insulin sensitivity in the modulation of insulin responses andits implication in energy utilisation and body composition. In addition, this thesis suggests than modulation of energy utilisation by external factors and feeding behavior cannot be achieved if metabolic characteristics suchas insulin sensitivity are not accounted at the individual level.
Document Type: Thèse de doctorat
Issue Date: 2022
Open Access Date: 13 June 2022
Grantor: Université Laval
Collection:Thèses et mémoires

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