Animal nutrition has advanced remarkably over the past 50 years. Compiling an overview of all these achievements is a daunting task and beyond the scope of this paper. The complexity of this task can be grasped when it is appreciated that the topic encompasses ruminant, monogastric (non-ruminant), laboratory, pet and wildlife nutrition; all with different gastrointestinal tracts (GIT) and nutrient requirements. Papers on the nutrition of these different animals have been presented to NSA meetings. This paper will focus on the nutrition of monogastric (poultry and pigs) and ruminant (cattle) animals, particularly advances in our understanding of: (1) protein and amino acid availability and (2) feed additives to improve nutrient utilisation, feed safety and modification of the gut microflora and (3) precision nutrition. In all these areas there are valuable lessons for human nutrition without specific discussion of animal models.
The change from formulating pig and poultry diets using total amino acid concentration to digestible amino acid concentration has produced considerable benefits when coupled with the ideal protein concept and the strategic use of crystalline amino acids. The success of this approach has informed the adoption of the digestible indispensable amino acid score (DIAAS) in human nutrition. Feed additives, including feed enzymes which reduce the adverse effects of non-nutrient feed components, including phytate, have had a major impact on improving feed utilisation. The mechanism of how feed enzymes and other additives (probiotics and prebiotics) work is in part, by modifying the gut microflora. This is most starkly demonstrated in ruminants where bromoform, a compound produced by seaweed and fungi, can significantly reduce methane production (> 90%) by rumen microorganisms, a major win for the environment. Over the last 5 decades, the study of the rumen microflora, which is central to ruminant nutrition, has led the way in our understanding of the form and function of the gut microflora. Fungi produce a plethora of secondary compounds, of which mycotoxins are highly toxic. Contamination of the food and feed supply chains by these compounds can have serious impacts on animal and human health. Mycotoxin toxicity can be greatly reduced by the strategic use of feed additives, in particular clay-based supplements that absorb the toxin in the GIT preventing absorption. With the successful application of this approach in animal nutrition it is now being applied to human food in developing countries.
Future animal nutritional research will address issues relating to identifying barriers to effective digestion and utilisation of nutrients, and approaches to improve feed utilisation. This will require nutrition scientists to increasingly combine their expertise with those specialising in other biological sciences, including molecular biology, microbiology and immunology. These endeavours will be driven, not only by the need to maximise biological and economic performance of farm animals, but also by societal issues (environment, welfare, traceability and use of genetically modified ingredients) and the sustainability of animal agriculture in the production of nutritious human food.