Investigation of structural and neurobiochemical differences in brains from high-performance and native hen breeds

Abstract

Selection of livestock has not only led to changes in the level of their performance but also modified their behavior. As a result, within a single species, we have to deal with different behaviors of different breeds. In our study, we assumed that the different behaviors within a species are due to differences in the morphology and physiology of behavior-related systems. Two breeds of hens were used as a model: the highly reactive, fearful and high-performance Leghorn breed and proactive, unselected Green-legged Partridge breed. The higher reactivity and fearfulness of Leghorn hens in comparison to the Green-legged Partridge breed may be related to the greater number of neurons in the paraventricular nucleus and anterior hypothalamus and the higher content of zinc and iron in the brain, as these elements are involved in neuronal conduction and myelination processes. The reactive behaviours of Green-legged Partridge hens may be associated with the lower number of neurons in the paraventricular nucleus and the anterior hypothalamus and the higher concentration of dopamine and copper ions in the brain. The analyses confirmed the hypothesis of the existence of interbreed differences in the morphology and physiology of behaviour-related systems, which most probably emerged through unintentional and correlated selection towards high production performance. Consequently, attention should be drawn that the selection of a given genotype (breed) towards a specific environment could lead to creation of highly specialised lines that may not achieve homeostasis in every maintenance system.

The Influence of Dietary Synbiotic on Agonistic Behavior, Stress, and Brain Monoamines via Modulation of the Microbiota–Gut–Brain Axis in Laying Hens

“…One previous study found DA turnover to be significantly reduced in the hippocampus and attributed this to fast uptake by dopamine transporters [18,74]. Lower dopamine turnover along with increased CORT may also represent higher stress levels [68], which is the opposite of what we observed in DA turnover levels in the hypothalamus of SYN birds.…”

“…Dopamine has also been shown to assist with memory formation in humans [67]. Dopamine levels can also reflect the welfare status of laying hens, as it can improve the animal's ability to cope with fear and stress [68,69]. In addition, it has been observed in rats that elevated DOPAC levels may be associated with a stressful environment [70].…”