Phytogenic Feed Additives as a Holistic Strategy for Sustainable Goat Production: A Review of Performance, Nutrition, Metabolic Stabilization, Health Status, and Genomic Regulation

As the livestock industry faces increasing pressure to adopt sustainable and environmentally conscious practices, there is a focused push to find natural feeding alternatives, chiefly those incorporating medicinal plants and herbal extracts known as phytogenic additives. These alternatives are characterized by high concentrations of bioactive compounds like essential oils and phenolics. They present a viable and attractive solution, given their capability to strategically modulate aspects of animal physiology across different biological domains. Empirical data compiled in this review confirms that phytogenic feed additives (PFAs) deliver broad positive effects on the health, productivity, and sustainability of goats. PFAs enhance feed conversion efficiency by increasing feed intake and body weight gain, and significantly improve milk production, and the nutritional value of milk by raising the level of healthy unsaturated fats. Functionally, they boost metabolic efficiency and sustainability by decreasing enteric methane gas production, optimizing rumen function by increasing propionic acid levels, and stabilizing systemic metabolism by balancing serum glucose and alleviating metabolic stress. Furthermore, PFAs strengthen the animal's defense mechanisms by enhancing the immune response through the stimulation of circulating immunoglobulins and adaptive immunity, while also operating at a molecular level to stimulate the expression of antioxidant genes and growth factors and repress pro-inflammatory gene products. Ultimately, PFAs represent a secure and effective strategy for promoting a sustainable and healthy goat production system.