Abstract
The increasing demand for sustainable agricultural practices prompts a reevaluation of feeding strategies in ruminant nutrition. Agricultural waste, often viewed as a by-product (BP), presents a promising opportunity to enhance the sustainability of livestock production systems. This review explores the potential of incorporating various agricultural BPs into ruminant diets. Utilizing these BPs reduces the environmental impact of livestock farming and contributes to the circular economy by recycling nutrients back into the food system. The nutritional composition of these wastes varies widely, and their inclusion in ruminant diets improves feed efficiency, animal performance and overall health. Research indicates that specific treatments, such as fermentation and ensiling, enhance the digestibility and nutrient availability of these materials. Moreover, incorporating agricultural waste into ruminant nutrition leads to financial benefits for farmers by reducing reliance on conventional feed sources. However, key challenges remain, particularly the need for further research to optimize inclusion rates and address potential anti-nutritional factors found in some agricultural wastes. Notably, adding these materials to ruminant diets results in 10%-30% reductions in feed costs and improvements of 5%-20% in key performance metrics, such as weight gain and milk production. These findings highlight the economic and sustainability benefits of utilizing agricultural BPs in livestock feeding practices. This review emphasizes the necessity of developing innovative and sustainable feeding strategies that leverage agricultural waste, calling for interdisciplinary approaches that combine animal nutrition, agronomy and environmental science. By adopting these practices, the livestock sector contributes to food security while minimizing its ecological footprint. Future research focuses on innovative processing techniques, effective management of anti-nutritional factors, and assessing long-term impacts on animal health and productivity. Additionally, examining the nutritional and health aspects of commonly used BPs, such as pomegranate, grape, pistachio, saffron, raisin, olive and tomato, is essential for fully understanding their potential in ruminant nutrition and guiding the development of targeted feeding strategies.