Taking into account a growing population and shifting diets, the world will need to produce 69% more food calories by 2050, which will in part come from poultry production. The main focus in poultry research currently is to meet this demand, in a post-antimicrobial era with reduced reliance on the current sources of protein. This is only possible by developing new and improved nutritional strategies and developing technology.

Dr. Natalie MORGAN - PoultryHub Australia poultryhub@une.edu.au

INTRODUCTION In 2017, international feed tonnage exceeded 1 billion metric tonnes for the first time, with the poultry industry representing 44% of total feed production. A current key focus in the poultry feed industry is the concept of ‘low protein’ diets. This move towards reducing protein in poultry diets has been driven by several factors.

A total ban on the use of meat-and-meal as the primary protein source in broiler diets was implemented in the EU in 2000, as a result of the Bovine Spongiform Encephalopathy (BSE) crisis. This saw global consumer preference for birds to be fed ‘vegetarian’ diets, resulting in heightened reliance on soybean meal as the main protein source.

There are obvious environmental implications associated with dependence on importing soybean meal from USA and South America, and these environmental impacts are accentuated further by the impact of nitrogen waste from poultry production on waterway pollution and ecosystems and harmful emissions such as ammonia. Furthermore, excessive dietary protein causes heightened incidences of enteric diseases in poultry and increased water consumption by the birds, thus resulting in poor production and wet litter problems. As a result, there has been amplified focus on feeding poultry low protein diets and supplementing them with amino acids, such as glycine, to reduce reliance on soybean meal whilst still ensuring performance parameters are met.

There is also increased interest in using alternative protein sources to reduce reliance on soybean meal, such as legumes, beans and peas, but at the moment their use is limited namely due to concern over their amino acid profile, prevalence of mycotoxins and ability to be pelleted. The advantages of supplementing poultry diets with protease enzymes has been an ongoing area of attention in recent years, with particular focus on using them to enhance the amount of dietary energy utilised by the bird and reduce the negative effects that unabsorbed protein in the gut has on enteric disease. Cost efficiency is obviously a major factor driving the use of low protein diets, and further research is needed in this field to make its extension practical, profitable and worthwhile for the poultry industry.

NON-STARCH POLYSACCHARIDES High worldwide feed prices mean it is essential that cost-effective ways to meet the dietary energy and amino acid needs of poultry are established. To accomplish this, technologies, such as processing techniques and exogenous enzymes, must be developed that accurately improve the nutritional value of fibre and high fibre co-products. Fibre is a highly variable and complex component of plant-based feed ingredients, and is perhaps the most poorly understood constituent of poultry diets. This is primarily because analytical methods used to characterise fibre cannot directly relate to fibre utilisation by the bird. It is imperative for future efficiency gain, and hence viability of productive poultry farms, that diets are formulated using non-starch polysaccharide (NSP) values as opposed to fibre values.

It is important to consider both soluble and insoluble NSP as their impact on digestion differ substantially. Insoluble NPS act as nutrient diluents and physical barrier to enzymes such as amylase and protease, thereby reducing efficient digestion of nutrients within the cell wall matrix of grains. Soluble NSP increase viscosity in the gastrointestinal tract of the bird, diminishing digestibility of starch, proteins and lipids. As well as dictating nutrient digestion, NSP also act as a predisposing factor for disease in poultry. Thus it is essential that the NSP content of grains is considered when formulating poultry diets.

EXOGENOUS ENZYMES Exogenous enzymes are almost ubiquitous in poultry diets, as the birds are not able to produce sufficient endogenous enzymes themselves, or produce them in the correct locations, to facilitate absorption of all components in normal feed or reduce the anti-nutritional factors in feed that limit digestion.

The use of enzymes such as xylanases, phytases and β-glucanases can reduce variability and enhance digestibility by releasing encapsulated nutrients, namely starch and protein, and reduce viscosity in the gastrointestinal tract. Recent advances in understanding about the modes of action of these enzymes have led to development of more bio-efficacious enzyme combinations that tackle specific substrates in a synergistic manner.

NSP-degrading enzymes improve digestibility and reduce viscosity in the gut; lower viscosity means improved nutrient utilization as enhances interaction between feed and enzymes and increases contact between the nutrients and absorptive surface of the gut. As a result, there is enhanced nutrient utilization, meaning there are less undigested nutrients available to act as predisposing factors for enteric disease and less wasted.

Phytates are storage form of phosphorus in plants that also bind to other minerals, proteins and energy, reducing their availability for the birds. As diets have become more complex and variable, concentrations of dietary phytate and, thus, the amount and availability of undigested substrates, has increased, which has a direct impact on microbiota composition and populations of non-beneficial bacteria in the intestine. Phytase enzymes are supplemented into poultry diets to eliminate the anti-nutritional effects of phytate, with a strong focus on improving mineral availability for bone and egg formation.

Ongoing research into enzyme development will mean they become more effective in maintaining function under a wider range of processing and digestive conditions. This could potentially result in manufacture of new enzymes that can reduce toxins produced during feed spoilage and facilitate digestion of substrates currently not able to be hydrolyzed in poultry, such as lignin and cellulose. There is also interest in how to improve the bioavailability of vitamins and minerals, to ensure they have increased stability during feed processing, have a lower environmental impact and are delivered when and where they are needed. An example of this is recent interest in hydroxychloride trace minerals.

USING FEED TO AID DISEASE MANAGEMENT Excessive and extensive use of antimicrobials and heightened interest in public security has given rise to concern about the development of antimicrobial-resistant human pathogenic bacteria. As a result, the use of in feed antimicrobials in poultry diets to enhance growth was banned in the EU in 2006. This was followed by a worldwide drive to use antimicrobials purely as therapeutic agents to treat bacterial infections or as prophylactic agents. One of the key barriers to complete withdrawal from antimicrobial use is the disease necrotic enteritis (NE). Necrotic enteritis costs the global poultry industry billions of dollars each year in production losses and control measures.

No alternative has the ability to exert the same extent and range of effects observed with antimicrobials on enteric disease, but extensive research is currently being conducted into preventative treatments that either focus on the predisposing factors that instigate the disease or directly target the causal agents of the disease. Predisposing factors that create a favourable environment for the bacteria dictate the likelihood of the disease occurring, with different bacteria having different substrate preferences. The digestibility and chemical composition of feed components determine the composition of the gastrointestinal environment in the bird. As a result, researchers have been exploring the role of different grains, processing techniques and diet compositions as predisposing factors for disease.

An effective alternative to antimicrobials should be safe for both the animal and consumer, have a significant and sustainable beneficial impact on poultry production and be easy to apply and store. Cost is obviously a major criterion, due to the low profit margins of poultry. Alternatives to antimicrobials promote gastrointestinal health by mechanisms such as altering pH, selecting for beneficial organisms and against pathogens and improving nutrient uptake and immune responses. Feed additives that can reduce gastrointestinal pH in the bird, such as organic acids and polyunsaturated acids, are advantageous because pathogenic bacteria cannot flourish at low pH.

There are also a number of feed additives that have a direct impact on microbiota balance in the bird; for example essential oils, such as cavacrol from oregano, can suppress pathogenic bacteria and help maintain the structure of the gut. Phytobiotics are plant derived natural bioactive compounds extracted from sources such as herbs and spices, which are added to feed due to their potential antimicrobial activity and ability to enhance immunity. The use of pro- and pre-biotics in poultry nutrition is a hot topic. Probiotics are cultures of living organisms that can enhance stability of the beneficial microbiota and reduce growth of pathogens and promote gut health and immunity. Prebiotics provide energy for the favorable bacteria which helps to eliminate the pathogens; the most common prebiotics are small chain sugars called oligosaccharides.

Yeasts are promising alternatives to antimicrobials because they show diverse biological activities against pathogens, such as reducing pH, preventing them binding to the gut and releasing compounds that directly attack them, as well as being rich in β-glucans which enhance immunity. There are conflicting results with the application of these different feed additives, and a great deal more research needs to be conducted in this field. It must also be noted that nutritional strategies alone cannot overcome the issues caused by removing antimicrobials, good management practices are also required.

FEED PRODUCTION TECHNOLOGIES As the availability of land and labour reduces, technology will play a major role in making poultry farming as efficient as possible, with robotics and innovative technology as emerging key players. In the future, it is very likely that information technology and feed systems will become even more intertwined, completely connecting the farm, feed mill, processing plant and consumer.

Digitalisation will mean that on-farm measurements can be collected and monitored in real-time; systems can be put in place to measure biological and chemical parameters in the land and gas outputs, to provide accurate insights into the diet strategy. As a result, feed availability will hopefully mirror demand, which will greatly increase efficiency and reduce waste.

Furthermore, advanced technologies for controlling digestion and utilisation of nutrients will mean reduced reliance on formulating diets based on just compositional analysis, resulting in extreme precision feeding that can be tailored to the specific grains available. The hope is that this will give way to the use of new feed ingredients and novel strategies for supplementing diets. This can be heightened further using nutrigenomic tactics, meaning diets will be closer to achieving the genetic potential of the bird by targeting the genes involved in meat quality and production.

The use of near-infrared spectroscopy (NIR) is already readily used in feed mills to allow for analysis of incoming raw materials in real time, so diets can be reformulated based on the specific batch of ingredient being fed. The accuracy of this approach can potentially be developed even further by using in vitro digestion modelling systems, which will provide the exact nutritional value of the raw materials and the final feeds. This suggests that future feed mills may become fully automated, meaning one person can single-handedly run and large feed mill, thus reducing reliance on labour.

The future of poultry production is dependent on the ability to meet consumer demands and increase efficiency and productivity sustainably and safely. Taking into account a growing population and shifting diets, the world will need to produce 69% more food calories by 2050, which will in part come from poultry production. The main focus in poultry research currently is to meet this demand, in a post-antimicrobial era with reduced reliance on the current sources of protein. This is only possible by developing new and improved nutritional strategies and developing technology.