MECHANISTIC UNDERSTANDING OF WATER HOMEOSTASIS IN DIVERGENTLY SELECTED BROILERS FOR LOW- OR HIGH-WATER EFFICIENCY

Genetic selection of the commercial broiler has created a fast growing, high yielding and efficient protein source capable of feeding the growing global population. Unfortunately, selection indices have neglected to include traits associated with water efficiency in their programs due to lack of knowledge surrounding feasibility of selection and potential impact on other economically important traits. As more regions experience fresh water scarcity, it is important to understand if selection for water efficiency can be utilized in selection programs. Therefore, the goal of this project is to further identify how selection for water efficiency has impacted economically important traits of the commercial broiler such as growth and meat quality under potentially adverse conditions such as periods of heat stress and to fully understand the mechanisms behind water efficiency and water utilization in broilers.Working with genetic lines that have been divergently selected for water conversion ratio/water efficiency for 4 generations, this project is divided into 2 main objectives.Objective 1. Identify the impact of divergent selection for water efficiency on muscle growth and meat quality. This can be accomplished through a traditional grow-out study using the low water conversion ratio (LWCR), high water conversion ratio (HWCR) and randombred control (MRB) broiler lines. At processing ages, meat quality can be evaluated through myopathy scoring, color, and pH.Objective 2. Determine the impact of chronic heat stress on broiler lines divergently selected for water efficiency. This objective can be further subdivided into 2 sub-aims. The first sub-aim will be to determine the effect of chronic heat stress on live performance and efficiency related characteristics. Using the LWCR, HWCR and MRB lines, birds will either be subjected to a thermal neutral environment of to a period of chronic heat stress, During this time, feed intake, water intake and body weight gain will be recorded as well as mortality. Following the period of heat stress, samples will be collecting for molecular analysis. These samples will be use for the second sub-aim in which tissues including the brain, tongue, small intestine, kidney and muscle will be subjected to real-time q-PCR and Western blotting. These samples will help build a better understanding of water efficiency and homeostasis within the research populations under two environmental conditions.