10 Optimizing the use of human-inedible animal feeds for livestock delivering to a circular sustainable global agri-food sector.

Abstract Abstracts: The drive to increase product output per animal in some sectors of ruminant livestock production and the expansion of monogastric livestock production has led to greater use of feeds such as cereal grains and soyabean meal that are potentially human edible. This trend has caused concern with livestock competing directly with the human population for a limited global area of cultivatable land on which to produce grain and legume crops. Monogastric livestock require similar nutrient provision as humans with high digestibility and quality, especially in relation to bioavailable protein and essential nutrients (fats, minerals and vitamins). Reasons for using potentially human-edible feeds in ruminant diets, as there are not the same direct nutrient requirements as with monogastrics, include increased total daily energy intake, greater supply of essential amino acids and improved ruminal balance between fermentable energy and degradable protein in high producing systems (e.g. intensive dairy and beef finishing). Soyabean meal, produced on land that has been in arable cultivation for many years can fulfill a useful role as a supplier of undegraded dietary protein in diets for high-yielding dairy cows and is the major protein source for pigs and poultry. However, in the context of sustaining the production of high-quality foods from livestock to meet the demands of a growing human population, the use of potentially human-edible feed resources should be reduced and restricted to scenarios where the crop has no discernable use as human food and then it should be used to strategically support livestock with the highest daily nutrient requirements (i.e. meeting requirements for energy and protein and rectifying imbalances in nutrient supply from human inedible basal feeds). There is therefore a need to optimize human inedible feeds for both monogastric, to supply the required level of high-quality digestible nutrients, and ruminant livestock, as currently forage-only systems can be associated with relatively low output per head and low nitrogen use efficiency compared to systems with greater reliance on human-edible feeds. Profitability on farm is driven by control of input costs as well as product value and examples are given of low-cost bovine milk and meat production with little or no reliance on potentially human-edible feeds. The potential of all-forage diets should be demonstrated for a wide range of ruminant milk and meat production systems. The development of human in-edible plant by-products, food waste, insect meal and processed animal protein for different livestock species is critically needed. The challenge for the future development of sustainable circular livestock systems will rely on the reduction of environmental pollutants and the optimization of human-inedible by-products to form the basal diet of monogastric livestock and are used to complement pastures and forage crops strategically rather than replace them in ruminant livestock.