Nutrient transporters in broiler chickens: intestinal gene expression profiles, functional roles, and influencing factors.

The primary role of the gastrointestinal tract in broiler chickens is nutrient assimilation, with transporter proteins facilitating the uptake of amino acids, peptides, monosaccharides, fatty acids, and minerals across the intestinal epithelium. Among these nutrient transporters, members of the solute carrier family are particularly important, and gene expression analyses targeting these transporters have provided informative insights into how birds adapt to diverse dietary, environmental, and physiological challenges to maintain nutrient homeostasis. These transporters are expressed either at the brush border membrane, where they facilitate the absorption of nutrients from the gut lumen into enterocytes, or at the basolateral membrane, where they mediate the transfer of nutrients from the enterocytes into the bloodstream. The expression of these transporters is influenced by a range of factors, including bird age, sex, intestinal segment, dietary substrate availability and source, as well as external stressors such as heat stress and pathogen exposure. While upregulation of transporter genes often suggests an enhanced capacity for nutrient uptake, it does not always correlate with improved growth performance, due to compensatory physiological responses and fluctuations in nutrient bioavailability. Understanding the regulation and functional dynamics of nutrient transporters presents valuable opportunities to develop targeted dietary and management strategies aimed at optimizing nutrient utilization and improving bird performance. This review summarizes current knowledge on the classification, function, and regulation of key nutrient transporters in broilers, highlights factors influencing their expression, and explores their implications for nutrition and production efficiency.