Dairy cows are able to convert fibrous materials, such as grass, roughage, and by-products from the food industry, into milk and meat, which justifies their role in food production. However, modern dairy farming is associated with major sustainability challenges, including greenhouse gas emissions. In order to develop sustainable future production, it is important to implement existing knowledge and fill knowledge gaps. The aim of this study was to systematically map the scientific literature on environmental, economic, and social sustainability at farm level in dairy farming. Literature published between January 2000 and March 2020 and with the geographical focus on Europe, North America, and Australia–New Zealand was included. In total, the literature search resulted in 169 hits, but after removing duplicates and papers outside the study scope only 35 papers remained. Of these, only 11 dealt with the three dimensions of sustainability, and several of these only mentioned one or two of the dimensions or set them in relation to that/those actually studied. Overall, the selected literature did not clearly explain how aspects of sustainability are interlinked, so possible negative or positive interactions between different aspects of sustainability dimensions remain unidentified.

Capric acid (C10:0), a medium chain fatty acid, was evaluated for its anti-methanogenic activity and its potential to modify the rumen biohydrogenation of linoleic (C18:2n-6) and α-linolenic acids (C18:3n-3). A standard dairy concentrate (0.5 g), supplemented with sunflower oil (10 mg) and linseed oil (10 mg) and increasing doses of capric acid (0, 10, 20 and 30 mg), was incubated with mixed rumen contents and buffer (1 : 4 v/v) for 24 h. The methane inhibitory effect of capric acid was more pronounced at the highest (30 mg) dose compared to the medium (20 mg) (-85% v. -34%), whereas the lower dose (10 mg) did not reduce rumen methanogenesis. A 23% decrease in total short-chain fatty acid (SCFA) production was observed, accompanied by shifts towards increased butyrate at 20 mg and increased propionate at 30 mg of capric acid (P < 0.001). Capric acid linearly decreased the extent of biohydrogenation of C18:2n-6 and C18:3n-3, by up to 60% and 86%, respectively. This reduction was partially due to a lower extent of lipolysis when capric acid was supplemented. Capric acid at 20 and 30 mg completely inhibited the production of C18:0 (P < 0.001), resulting in an accumulation of biohydrogenation intermediates, mainly C18:1t10 + t11 and C18:2t11c15. In contrast to effects on rumen fermentation (methane production and proportions of SCFA), 30 mg of capric acid did not induce major changes in rumen biohydrogenation as compared to the medium (20 mg) dose. This study revealed the dual action of capric acid, being inhibitory to both methane production and biohydrogenation of C18:2n-6 and C18:3n-3.

We systematically mapped the scientific literature on the sustainability of pig production at farm-level. Sustainability was considered holistically, covering its economic, environmental, and social dimensions, each consisting of a broad range of different aspects that may contradict or reinforce each other. Literature published between January 2000 and March 2020 with a geographical focus on Europe, North America, Australia, and New Zealand was included. A standard template with predefined keywords was used to summarise aspects of each sustainability dimension covered in identified papers. We found that papers analysing environmental sustainability were more frequent than papers analysing economic or social sustainability. However, there are many different aspects within each dimension of sustainability, hampering comparisons between studies. In addition, each dimension of sustainability has many sides, making it difficult to compare different studies, and different dimensions and aspects may have complex interrelations. Our systematic literature review revealed that these interrelations are not well understood and that possible trade-offs or synergies between different aspects of sustainability dimensions remain unidentified. This systematic mapping of the current literature on farm-level sustainability in pig production can support a more informed discussion on knowledge gaps and help prioritise future research at farm-level to enhance sustainability in pig production.

The sustainability of future poultry production needs to be improved in order to meet global challenges. The global chicken population has expanded significantly in recent decades, due to increased human demand for eggs and chicken meat. Therefore, it is critically important to mitigate challenges to the sustainability of modern poultry production, such as pollution, the depletion of finite natural resources and animal welfare issues. This study systematically mapped the scientific literature on farm-level sustainability in egg and chicken meat production. The concept of sustainability was considered holistically, covering its economic, environmental and social dimensions, each consisting of a broad range of different aspects that may contradict or reinforce each other. The literature published between January 2000 and March 2020 with a geographical focus on Europe, North America and Australia–New Zealand, were included. The literature search resulted in a total of 428 hits, but after the exclusion of articles that did not match the scope of the study, only 26 papers remained for the systematic mapping. Of these, only three papers covered all three dimensions of sustainability. Aspects of economic sustainability were addressed in 10 papers, aspects of environmental sustainability in 18 papers, and aspects of social sustainability in 23 papers. The findings in this study are an important foundation for the discussion and prioritisation of future actions to increase knowledge of farm-level sustainability in egg and chicken meat production.