Energy allocation and behaviour in the growing broiler chicken

Abstract

Broiler chickens are increasingly at the forefront of global meat production but the consequences of fast growth and selection for an increase in body mass on bird health are an ongoing concern for industry and consumers. To better understand the implications of selection we evaluated energetics and behaviour over the 6-week hatch-to-slaughter developmental period in a commercial broiler. The effect of posture on resting metabolic rate becomes increasingly significant as broilers grow, as standing became more energetically expensive than sitting. The proportion of overall metabolic rate accounted for by locomotor behaviour decreased over development, corresponding to declining activity levels, mean and peak walking speeds. These data are consistent with the inference that broilers allocate energy to activity within a constrained metabolic budget and that there is a reducing metabolic scope for exercise throughout their development. Comparison with similarly sized galliforms reveals that locomotion is relatively energetically expensive in broilers.

First Evidence of Realized Selection Response on Fillet Yield in Rainbow Trout Oncorhynchus mykiss, Using Sib Selection or Based on Correlated Ultrasound Measurements

“…For example, in the Illinois corn selection experiment for protein content, the high line still increases over 25% protein after 100 generations, while the low line seems to have reached a plateau at approximately 5% protein (Moose et al, 2004). In a system closer to the question of fillet yield in fish, increasing breast yield in broiler chicken has led to increased respiratory capacity needs that cannot be met efficiently, causing pulmonary diseases (Wideman, 2001;Tickle et al, 2018). The biological limit for fillet yield is unknown in rainbow trout.…”

Embryonic Thermal Manipulation Affects the Antioxidant Response to Post-Hatch Thermal Exposure in Broiler Chickens

“…Due to impaired metabolic function and expensive energetics, broilers are especially vulnerable to heat stress, which occurs when the broiler is unable to adequately dissipate body heat to the environment [6]. Rising global temperatures have consolidated the threats of heat stress to the development and wellbeing of broiler chickens, and such increases in temperature are exacerbated during the hotter seasons [7].…”

HSF3 and Hsp70 Expression during Post-Hatch Cold Stress in Broiler Chickens Subjected to Embryonic Thermal Manipulation

“…Broiler chickens are classified as homoeothermic animals, meaning that they can only maintain their body temperature efficiently when ambient temperatures are within certain limits [7,8]. After decades of selective breeding, commercial broilers produce more body heat yet have an impaired ability to dissipate it, making them highly susceptible to thermal stress [9,10]. Thermal stress can arise at many stages in the typical broiler's life, and climate change is endangering the welfare and stress levels of broilers around the world [11].…”