Differential hepatic gene expression in the broiler chicken in response to the combined stressors of food withdrawal, catching and transport at the end of production

Broiler (meat) chickens experience the combined acute stressors of food withdrawal, catching and transport (FCT) prior to slaughter as part of normal commercial practice at the end of their lives. This has associated physiological consequences, potentially affecting both welfare and meat quality, some of which are mediated through altered hepatic function. This study compared global hepatic gene expression between control birds and those exposed to commercial FCT using 20K chicken oligonucleotide microarrays. In response to FCT, 733 genes were differentially expressed of which 486 could be mapped onto the genome. The principal molecular and cellular functions thus affected by FCT involved lipid and carbohydrate metabolism with a suppression of mRNA expression for genes involved in lipogenesis, glycolysis and glycogenolysis and an induction of those involved in gluconeogenesis, fatty acid metabolism and ketone synthesis. There was also significant differential expression of genes associated with cellular control and immune function. These stressful events associated with FCT in commercial broiler chickens altered expression of hepatic genes associated with energy metabolism, with exhaustion of stored hepatic and pectoral muscle glycogen. A better understanding of FCT-induced stress through the use of gene expression arrays may in future inform husbandry practices, to improve both welfare and meat quality.