Summary

Appetite in birds is driven by nutritional status. Energy homeostasis is one of the main drivers of feed intake in chickens; however, other nutrients such as amino acids or calcium (Ca) also contribute to the onset of hunger/satiety, what has been referred to as nutrient-specific appetite. Reportedly birds seem to adjust feed intake and change feeding behaviour in response to dietary energy, amino acids, Ca, Na, organic acids, fibre, fats, sugars and several bitter compounds. However, current practices in feed formulation do not take into account the influence on appetite of several of these nutrients (particularly the non-essentials) and nutrient-nutrient interactions. Moreover, individual variations in broiler feeding behaviour have not yet been fully explained. It is known today in mammals that nutrient-specific appetite is driven by receptors such as CaSR (for Ca), T1R1/T1R3 (for Glu/Gln), GPR41/43 (fatty acids) or T2R (for bitter). The allelic variance of the receptors is correlated with taste sensitivity and control of feed intake. Some of these receptors have been reported in chickens not only in peripheral tissues but also in the hypothalamus (the main organ in the control of energy homeostasis). Consequently, nutrient sensing in broilers could account for phenotypic differences in feed intake. Our project proposes to study the nutrient specific appetite of 3 phenotypic subpopulations of broiler chickens: high, medium and low performers. This information will be collated into formulation guidelines to decrease the marginal costs of diets and improve efficiency of broiler growth with higher flock uniformity.

Program

Chicken Meat

Research Organisation

The University of Queensland

Objective Summary

The aim of the research project is to provide quantitative evidence to adjust the marginal nutrient levels in the broiler formulas to decrease feeding costs while improving flock efficiency and uniformity.
The specific objectives will be:
1- To identify and characterize three subpopulations of broiler chickens based on performance: High, medium and low performers (poultry producer partnership with Baiada Select Poultry).
2- To determine behavioural differences in nutrient-specific appetite between the three phenotypic groups using a modification of the double-choice by Gentle (1972).
3- To identify the main nutrient sensors involved in the specific appetite and to quantify their level of expression in oral tissues of the three subpopulations. The main targets will be CaSR, T1R1, T1R3, T2Rs (3 receptors), GPRC6A, GPR41/43, ENaC(α,β,γ,δ), TRPM5, α-Gustducin and PLCβ2.
4- To study the allelic variations (and potential sensitivity) of the main nutrient sensors involved according to the behavioural tests. Correlate phenotypic with genotypic variation related to nutrient specific appetites.
5- To identify excess and shortage of specific nutrients that link the specific appetite shown in behavioural data and the genomic information (the current hypothesis is based on non-essential amino acids, Ca, Na, organic acids, bitter compounds and fats).
6- To collate all the information in formulation guidelines to assist in decreasing the marginal costs of feeds and increase dietary efficiencies in broiler production while reduce farm waste outputs.
7- To test the novel formulation guidelines in a commercial setting in partnership with a poultry enterprise.