Nutritional solutions for appetite regulation in livestock and poultry: A review.

The regulation of appetite in livestock and poultry is a complex process that involves the integration of central and peripheral physiological mechanisms. The process is regulated by nutritional, environmental, and genetic factors. This review synthesises current understanding of the neuroendocrine and gut-brain axis pathways that regulate appetite, including hypothalamic signalling via agouti-related protein (AgRP)/neuropeptide Y (NPY) and proopiomelanocortin (POMC)/cocaine- and amphetamine-regulated transcript (CART) neurons, as well as peripheral modulation by gut hormones (e.g., ghrelin, leptin [LEP], and glucagon-like peptide-1 [GLP-1]) and microbial metabolites (e.g., volatile fatty acids [VFA]). Distinct species-specific characteristics, such as the use of rumen fill and VFA of ruminants, visual feed preference in poultry, and taste-driven intake in swine, underline the need to develop proper nutritional strategies. The regulatory and potential mechanism of some important dietary factors, such as energy density, protein and amino acid balance, micronutrients and functional additives (e.g., phytochemicals, probiotics, and acidifiers), are discussed in this paper, which can enhance satiety or stimulate feed intake. Furthermore, the latest advancements in species- and stage-specific nutritional intervention strategies for swine, ruminants, and poultry are summarised. Emerging approaches, including novel alternative feed resources, multi-omics analysis, feed-focused genome editing, and precision feeding systems, offer promising strategies to improve feed efficiency and animal health. Future research should integrate molecular biology, nutrigenomics, and smart farming technologies to develop sustainable, species-specific strategies for appetite modulation, thereby enhancing livestock productivity and welfare.