Evidence of animal productivity outcomes when fed diets including food waste: A systematic review of global primary data

Enormous amounts of food waste are generated that could potentially be used for livestock feeding to support sustainable food production and reduce climate and resource burdens. Many studies have documented animal productivity parameters (growth, yield, feed use efficiency) when fed food waste, but their findings remain fragmented. Our objective is to synthesize results from these studies to uncover collective evidence on how animal productivity is affected. A systematic literature review identified 102 studies, which originated from 31 countries and encompassed all major food-producing animal species fed food waste of various types and rates. The field-based primary data were normalized to discern patterns and trends. Animals in 75-77 % of all cases performed as optimally or increased productivity compared to those fed control diet; the remaining 23-25 % had decreased performance. Meta-analysis of a subset of data indicated that pig growth did not differ between control and treatment diets of varying food waste rates. Ultimately, balancing major nutrients from all feed ingredients are key for maintaining optimal productivity while pursuing sustainability.