A Project Designed to Promote Environmentally Viable Chicken-Meat Production via Enhanced Nutrition, Gut Integrity and Housing

I. BACKGROUND

The scale of the Australian chicken-meat industry has increased at an extraordinarily rapid rate so that now chicken-meat is clearly the first preference of consumers in comparison to pork, beef and lamb. In 1990/91, the Australian population was 17.2 million with a per capita chicken-meat consumption of 23.9 kg; however, this increased by 61.0% to 27.7 million people and consumption increased by 100% to 47.8 kg over the 30 years to 2020/21. As a direct consequence, the number of birds processed expanded by 138% (675.3 versus 283.7 million) and the volume of chicken-meat produced increased by 231% (1.285 versus 0.388 million tonnes) over the three decades (Australian Chicken Meat Federation, 2022). From a Treasury forecast, the Australian population is projected to increase to 35.9 million in 2050 and chicken-meat consumption may reach 52.5 kg. If these assumptions are valid, chicken meat production will need to increase, from an already high base, by a further 29.6% from 1.285 to 1.665 million tonnes over the next 30 years and if slaughter weights remain constant the number of birds processed will increase from 675 to 875 million. Global poultry production has been projected to increase by 72% from 105.6 million tonnes in 2020 to 181.3 million tonnes of chicken-meat by 2050 (Alexandratos and Bruinsma, 2012). This represents an average annual growth rate of 1.82%, but there are already indications that this is conservative. These forecasts emphasise the need for environmentally viable chicken-meat production to meet this demand in a responsible manner both in Australia and overseas.

Presently, broiler chickens have the best conversion rate of animal feed to meat for human consumption coupled with the smallest environmental footprint in terms of energy and water used for edible meat output across terrestrial animals (Vaarst et al., 2015). The estimated efficiency of protein deposition of 33.3% in broiler chickens clearly exceeds the estimates of 23.3% in pigs and 12.1% in feedlot cattle (Wu et al., 2014). Similarly, it was predicted that of greenhouse gas emissions (as CO2 equivalents) generated from meat production in 2020 that 63.1% would arise from beef, 29.8% from pork, but only 7.1% from chicken-meat production. Australia imported 1.180 million tonnes of soybean meal in 2020 and the majority of these importations, perhaps 750,000 tonnes with an approximate landed cost of A$800 per tonne, would have been absorbed by the local chicken-meat industry. This reliance on imported soybean meal is incompatible with sustainable local production, which is only compounded by neotropical deforestation in South America to harvest soybeans (Gasparri et al., 2013). Therefore, a core objective of the project is to reduce Australia’s dependence on imported soybean meal via an integrated, multi-faceted approach.

The fundamental objective is to enhance feed efficiency, as any strategies that will improve feed conversion ratios (FCR) will axiomatically advantage sustainable chicken-meat production (Cowieson and Selle, 2011). Therefore, five Australasian research institutions have combined to form a partnership, in association with seven industry partners, to develop an integrated program to promote sustainable chicken-meat production. The genesis of this partnership was the successful bid to AgriFutures Australia for financial support of the extensive project envisaged and an indication of the scope and the participants involved in this project is provided in Table 1.

Table 1 - Research institutions, program descriptions and lead investigators involved in the AgriFutures Australia chicken meat project.

II. PROJECT OUTLINE

Nutrition-based Program One will focus in developing transgenerational strategies. The overarching aim is to improve protein utilisation in meat chickens through maternal programming and in ovo paired with early-feeding programs. Nutritional constraints imposed on broiler breeders, such as a scarcity of dietary protein, trigger physiological adaptations that improve the growth rate and feed conversion under low dietary protein regimes in the progeny (Moraes et al., 2014; Lesuisse et al., 2018). Reducing dietary protein decreases nitrogen excretion in broiler breeders as well as the footprint of the broiler progeny (Meda et al., 2011). Broiler progeny hatched from feed-restricted breeders, as commonly practiced, has been shown to experience reduced growth and increased abdominal fat in comparison to more generous feeding regimes (van der Waaij et al. 2011). In addition, Program One will capitalise on the potential of in ovo interventions to influence embryonic development (Uni and Ferket, 2004; Kadam et al., 2013; Siwek et al., 2018). The in ovo nutrition practices will involve specific amino acids and other essential nutrients to target early gut and immune system developments during late stages of embryogenesis. The stimulation of embryonic development will liaise with early-feeding strategies in hatchlings. The anticipated result is a long-lasting impact on an improved feed efficiency and protein utilization during the life of the chicken.

Improving the utilisation of dietary carbohydrates, especially starch, and protein via precision feeding is another cornerstone to be addressed in Program Two. The digestion rate of wheat starch is more rapid than that of maize and sorghum (Giuberti et al., 2012); however, some slowly digestible starch has been shown to advantage broiler performance (Herwig et al., 2019). Moreover, dietary starch:protein ratios hold relevance for the growth performance of broiler chickens as demonstrated by Sydenham et al. (2017). Interactions between these two macro-nutrients are pivotal as maize-based diets with high starch levels have been shown to compromise apparent amino acid digestibility coefficients, particularly in the proximal and distal ileum of broiler chickens (Moss et al., 2018).

Decreasing our dependence on imported soybean meal via the development and adoption of reduced-crude protein (CP) diets and/or the identification of alternative protein-rich feedstuffs is the objective of Program Three. Reduced-CP diets have the potential to halve soybean meal importations via dietary inclusions of non-bound (synthetic, crystalline, feed-grade) amino acids to meet amino acid requirements at the expense of soy protein (Selle et al., 2020). This is a real challenge, especially for wheat-based diets (Selle et al., 2022), which demands further investigations into the digestive dynamics of starch/glucose in alignment with protein/amino acids (Liu and Selle, 2017). Obviously, alternatives to soybean meal are not confined to non-bound amino acids and extend to Canola meal (Ajao et al., 2022). This is of extreme relevance to Australia and there is scope to develop improved Canola meal production processes and the possibility of producing Canola protein isolates and/or concentrates. Additional alternatives consist of a range of legumes including field peas (Wang and Daun, 2004) and novel protein sources including insect protein (Khan SH, 2018) and krill meal (Ryś and Koreleski, 1979).

The relationships between the gut microbiota, dietary nutritional inputs and the host will be explored in Program Four as the gut microbiota can influence both broiler growth performance and flock health (Stanley et al., 2014). As one example, Ndotono et al. (2022) reported that inclusions of black soldier fly larvae as a protein source reshaped the gut microbiota to the advantage of gut health, immune response and food safety. Also, elucidating the mechanisms whereby probiotics positively impact the gut microbiota to the benefit of the avian host (Stanley et al., 2016) will constitute part of Program 4.

The issues of litter quality specifically (Dunlop et al., 2016) and, more generally, on better housing or accommodation for broiler chickens during the grow-out phases will be the focus of Program Five. Bird welfare is becoming an increasingly important issue (Bessei, 2006; Tahamtani et al., 2020) and, as discussed by Garland (2018), the incidence of foot-pad lesions is a sensitive barometer in this respect under practical conditions. There is accumulating evidence that reducing dietary CP results in enhanced litter quality and, consequently, in reduced incidences of foot-pad lesions (Van Harn et al., 2019). In fact, this is just one example of how the different programs overlap in the overall project.

Finally, and arguably most importantly, the role for Program Six is to integrate the outcomes generated by the project and communicate them to the chicken-meat industry so that their adoption will be facilitated. In addition, there will be a strong focus on mentoring students with the provision of scholarships, exchange programs between research institutions and support for industry placements. Annual stakeholder meetings will be held to showcase the progressive outcomes from each of the six programs. It is confidently anticipated that the integrated and coordinated inputs from the participating research institutions to this AgriFutures Australia project will be of real benefit to local chicken-meat production.

Presented at the 34th Annual Australian Poultry Science Symposium 2023. For information on the next edition, click here.