Theoretical Framework and Molecular Evidence for Gut-Brain Axis Regulation of Feed Intake in Goats Under Nutritional Stress in Semi-Arid North West Nigeria

Feed intake regulation in ruminants under nutritional stress involves complex bidirectional communication between the gastrointestinal tract and the central nervous system, yet the neuroendocrine molecular mechanisms of this gut-brain axis in Nigerian small ruminants under field conditions represent a largely unexplored research frontier. This doctoral study developed an original theoretical framework for gut-brain axis regulation of feed intake in Red Sokoto goats under nutritional stress in Zamfara and Kebbi States, North West Nigeria. Eighty goats were subjected to two experimental periods of controlled nutritional restriction (fifty percent of estimated maintenance requirement for six weeks) followed by realimentation. Plasma concentrations of ghrelin, leptin, glucagon-like peptide-1, peptide tyrosine tyrosine, neuropeptide Y, and cholecystokinin were quantified by immunoassay at baseline, during restriction, and during realimentation. Hypothalamic tissue from slaughtered subsets was analysed by real-time PCR for neuropeptide Y and pro-opiomelanocortin expression. Ghrelin surged during restriction and was the dominant orexigenic signal, with plasma concentrations doubling by week three. Peptide tyrosine tyrosine and glucagon-like peptide-1 declined during restriction but rose sharply above baseline during realimentation, suggesting a compensatory satiety suppression failure at realimentation onset. Hypothalamic neuropeptide Y was upregulated threefold during restriction and returned to baseline by week three of realimentation. The developed theoretical framework integrating peripheral gut hormones with central neuropeptide expression patterns provided a significantly better fit to feed intake variance than single-hormone models. These original findings advance ruminant nutritional neuroendocrinology and have applied significance for livestock management in semi-arid Nigeria. Keywords: gut-brain axis, ghrelin, feed intake regulation, nutritional stress, goats.