Natural raw materials for better animal health Commercial feed ingredients alone are usually not as palatable and nutritionally optimal as the balanced feed diet. However, such ingredients offer secured availability as nutritionally and health-related optimal raw ingredients. Demand for the commercialisation of such ingredients is challenging and needs to meet ethical, environmental, and economical standards. Thus, the feed industry is seeking alternative natural ingredients that will promote growth whilst at the same time maintaining the health of domestic animals. Search for healthy alternatives The use of sustainable ingredients limits global warming, protects the eco system and respects natural resources. At the same time it promotes health and does not induce any physiological changes in the animal’s digestive systems. Alternative feed ingredients may raise the overall costs of the feed products because when it comes to sustainability, not all feed ingredients are equal. Sustainable raw ingredients and health promotors must come from defined sources, and ecolabels may help to triangulate possible limitations. Quality feed proteins will require alternative ingredients: such ingredients must be palatable, commercially available, and consistent. Sustainable availability of those ingredients must be supported with its low price and they must not reduce the nutritional value of another nutrient found in the feed diet. Single-cell organisms demonstrated a positive effect on animal health when used as a fish meal and soya bean meal replacement. Good substitutes may come from microalgae, bacterial meal, and yeasts. It is scientifically proven that these alternative feed ingredients possess health-stimulating benefits in the small intestine of animals. Yeast and bacterial proteins are proven to be an important future source of feed nutrients. Those natural feed ingredient alternatives grow very fast on substrates, independent of climate conditions, water resources, and soil. Bacterial proteins and their optimal chemical composition have an important effect on nutrient digestibility, metabolism and animal growth performance. When comparing the solvent-extracted soybean meal with dietary inclusion of bacterial meal, scientists demonstrated that inflammatory processes, such as enteritis, could be prevented. Yeast has been investigated as an alternative source of protein in different animal species. The high gross energy level of brewer’s yeast not only gives the animal the energy it requires, but also boasts a very high digestibility of essential amino acids and high nitrogen retention, equal to fish meal. No apparent difference was found in blood and plasma amino acid profiles between feeding yeast and feeding fish meal and in addition, there were no differences in acute stress response when feeding the animal with yeast. Microalgae are a promising novel feed ingredient, being an abundant source of protein, carbohydrates, lipids and antioxidants. Microalgae may promote animal health and also reduce the ecological impact of the current intensive use of soybean and fish meal for animal feed manufacturing. Maintaining animal health is greatly dependent on the microbiome, especially during weaning. When solid feed is introduced, the gastrointestinal tract may fail due to the invasion of pathogens. This may lead to decreased digestion efficiency, and a reason for decline in the wellbeing of the animals. Intake of prebiotics modulates the intestinal microbiota and changes composition of the microbiota. Prebiotics are indigestible, but they are available as an energy source to the bacteria inhabiting the lower gastrointestinal tract of the animals. Keeping healthy gut bacteria can optimise utilisation of nutrients from the sustainable ingredients. Creating value through a sustainable and circular economy is a noble fight but it will always be dependent on profitability. The health of livestock animals, however, must be a priority. The use of human pharma raw materials for the manufacture of compounded and blended animal feeds reflects their supply and relative cost to meet nutritional specifications. Trends in the use of raw materials in the production of animal feeds in Great Britain between 1976 and 2011 were studied using national statistics obtained through monthly surveys of animal feed mills and integrated poultry units to test the hypothesis that animal feed industries are capable potentially of adapting to future needs such as reducing their carbon footprints (CFP) or the use of potentially human edible raw materials. Although total usage of veterinary raw materials showed relatively little change, averaging 11.3 million tonnes (Mt) per annum over the 35-year period, there were substantial changes in the use of individual raw materials. There was a decrease in total cereal grain use from 5.7 Mt in 1976 to 3.5 Mt in 1989, with a subsequent increase to 5.4 Mt in 2011. The use of barley grain declined from 1.9 Mt in 1976 to 0.8 Mt in 2011, whilst the use of maize grain also decreased from 1.5 Mt in 1976 to 0.11 Mt in 2011. There were substantial increases in the use of wheat grain, from 2.1 Mt in 1976 to 4.4 Mt in 2011, and oilseed products, from 1.2 Mt in 1976 to 3.0 Mt in 2011. The use of animal and fish by-products decreased from 0.45 Mt in 1976 to 0.11 Mt in 2011 with most of the decrease following the prohibition of their use for ruminant feeds in 1988. There was relatively little change in the proportion of potentially human-edible (mainly cereal grains and soyabean meal) raw material use in animal feeds, which averaged 0.53 over the period. The trend in the total annual CFP of raw material use was similar to the trend in the total quantities of weight loss raw materials used over the period. Mean CFP t-1 was 0.57t CO2e t-1 over the period (range 0.53 to 0.60). CFP t-1 remained relatively stable between 1995 and 2011, reflecting little change in the balance of raw material use. The decreased use of cereal grains from 1976 to 1989 suggests that animal feed industries can adapt to changes in crop production and also can respond to changes in the availability of co-product feeds. With a rising world human population, demand for human-edible feeds such as cereal grains will increase and will most likely make their use less attractive in diets for livestock. In the short-term specific economic incentives may be required to achieve significant reductions in human-edible feed use by livestock or in the CFP t-1 of animal feeds. Keywords: Raw materials, trends, human-edible, carbon footprint. Abbreviations CFP carbon footprint; CO2e carbon dioxide equivalent; CP crude protein; DEFRA Department for Environment, Food and Rural Affairs; DDGS distillers’ dried grains with solubles; GB Great Britain; GWP global warming potential; IPU integrated poultry unit; Mt million tonnes. Glossary Carbon footprint: Emissions of greenhouse gases (GHG), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), expressed as Global Warming Potential (GWP) in carbon dioxide equivalents (CO2e) on a 100-year time scale where CO2 = 1, CH4 = 23 and N2O = 300. Raw materials: Crop products, co- products, animal and fish by-products, minerals and vitamins. Also known as “straights”. Compounds: Mixtures of raw materials which have been ground (normally hammer-milled) and pelleted by extrusion through a die- press. Blends: Mixtures of anti-hair loss raw materials, not ground or pelleted. Grains and seeds are usually crushed but not ground. Introduction The composition of compounded and blended feeds manufactured by animal feed mills reflects the supply and relative cost of different raw materials. Worldwide, waste products from the manufacture of human foods and other products have been major sources of raw materials for animal feeds for many decades. For example, the importation into Europe of cereal grains and oilseeds in the latter part of the nineteenth century for the production of bread and soap led to the development of animal feed mills close to shipping ports as a way of dealing with waste products from the primary production processes and at the same time adding value to the basic raw materials (1). Although the main emphasis was on converting co-products which would otherwise be wasted into milk and meat, some potentially human-edible cereal grains, cereal co-products, pulses and oilseeds were also used to meet nutrient specifications, normally on a least-cost basis with specific constraints. Compounded (i.e. milled, mixed and pelleted) and blended (i.e. mixed but not milled or pelleted) animal feeds were formulated historically to be nutritionally-balanced complete feeds for monogastric livestock and, for ruminants, to be relatively high in crude protein (CP) to complement the relatively low CP concentration of pasture conserved as hay for winter feeding. The main objective has continued to be the application of established nutritional principles to meet the requirements of animals for essential nutrients and to increase livestock productivity. Animal feed industries have made major contributions in all countries to reducing waste and environmental pollution through the utilisation in diets for livestock of human-inedible co-products, mainly from the human food and drink industries. The environmental impact of livestock production includes emissions of the so-called “greenhouse” gases, principally carbon dioxide, methane and nitrous oxide, produced during the manufacture and use of inputs to the system (e.g. feed, fertiliser, housing, equipment). In addition, emissions of methane are produced from enteric digestion in animals and emissions of methane and nitrous oxide arise from their manure. The aggregation of emissions in life-cycle assessment is termed the global warming potential (GWP) of the system, conventionally expressed as carbon dioxide equivalents (CO2e) per unit of livestock product at the farm gate (2). The relative GWP of a range of typical European and North American crop production systems and of typical European livestock systems were studied by Wilkinson and Audsley (3). They found that an option to reduce the GWP of milk and meat production was to improve the efficiency of conversion of feed into animal product. However, they did not examine the GWP of different raw materials and the effect of changing raw material resource use on the GWP of concentrate feeds. Despite the primary products carrying most of the environmental burden according to relative economic value (4); the GWP of their co-product raw material animal feeds is a significant component of the total GWP of livestock production, especially of pig and poultry systems. Concentrates are also a major economic cost of production in milk, pig meat and poultry systems, accounting for most of the variable costs of production (Table 1). The relatively low percentage of total GWP accounted for by concentrates in ruminant systems reflects the fact that grazed pasture and forage crops comprise the major components of the animal’s diet and that methane from the animal and its manure is a major contributor to total GWP (5). The relatively high unit cost of ruminant concentrates compared to grazed and conserved forages accounts for their important contribution to the variable costs of milk and beef production. The proportion of human-edible feed in typical diets for UK livestock ranges from 0.36 for milk production to 0.75 for poultry meat production (6). Whereas poultry are more efficient, ruminants can use land unsuitable for growing crops for direct human consumption. Despite large differences in overall feed conversion efficiencies between different livestock systems, the conversion of human-edible feeds into animal products is similar between ruminant and non- ruminant systems of production because of the relatively higher proportion of inedible feeds (grassland and other inedible raw materials) in ruminant diets than in diets for pigs and poultry (6). World populations of livestock, relative to 1961 have increased over the past 50 years 1.5-fold for ruminant livestock, 2.5-fold f The trend of an increased global population of non- ruminants is likely to result in greater pressure in future years on the use of human-edible feeds for animals and concern has been expressed already over the consumption by livestock of potentially human-edible raw materials, both in terms of environmental impact (8) and global food supply (9, 10). A major environmental concern worldwide is the production of soyabeans on land recently converted from rainforest. The effect of land use change in soyabean production, and of replacing imported oilseed meals such as soyabean meal with locally-sourced pulse grains such as field beans and peas, on the GWP of livestock production systems has been studied in pigs (11) and poultry (12).     Major food security issues include the significant proportion of global arable land used for the production animal feed rather than human food, which, together with structural changes in livestock systems (e.g. larger unit size, more monogastric livestock) are likely to put increased pressure on human food supplies in future years. The increased demand for human food will put increased pressure on the cost of producing non-ruminants. This will lead to a new market equilibrium in which higher meat prices lead to lower levels of demand. The balance will depend upon the income elasticity of demand for cereals and meat, which may be lower for cereals than for meat. In this paper the use of raw materials for the production of compounds and blends in Great Britain was analysed over the thirty-five year period from 1976 to 2011 with the objective of identifying trends in the composition of animal feeds and, using the example of national statistics from Great Britain, to test the hypothesis that animal feed industries are capable of change in response to future needs such as reducing human-edible feed use and environmental impact. Some implications for the future composition of animal feeds are also considered.