Farm animals - research publications

Face of a bull calf with ear tag

Since at least the 1960s there has been increasing awareness of the effects of intensive farm animal production on animal welfare. One of the events that opened the eyes of a great many people was the publication of the book 'Animal Machines: The New Factory Farming Industry' by Ruth Harrison in 1964. In the book Harrison describes some of the practices of modern animal production, such as keeping laying hens in small cages, the tethering of gestating sows, and keeping bull-calves one-by-one in small crates.

"Life in the factory farm," she wrote, "revolves entirely around profits, and animals are accessed purely for their ability to convert feed into flesh or 'saleable products'." However, even though many people seem to agree with this, the consumption of meat and other animal products is still on the rise, not only in the West but even more dramatically in countries like India and China. Thus, ethical issues concerning the way farm animals are being treated will not go away.

On this site you will find various publications about farm animal ethics and welfare within the categories listed below. The categories are sorted alphabetically.  










    Market driven initiatives can improve broiler welfare – A comparison across five European countries based on the Benchmark method

    Sandøe, P., Hansen, H. O., Forkman, B., van Horne, P., Houe, H., de Jong, I. C., Kjær, J. B., Nielsen, S. S., Palmer, C., Lottrup, H., Rhode, H., & Christensen, T. (2022) 
    Poultry Science.


    Two kinds of initiatives exist to ensure welfare in broiler production: welfare legislation, where all broiler production in a country or region must comply with legally defined welfare standards; and market driven initiatives, where part of the production must meet specific welfare standards and is sold with a particular label, typically at a price premium, or as part of minimum welfare standards defined by a retailer, a fast-food chain or the like. While the effects of national legislation may be undermined by price competition from lower-welfare imported products, the effects of market driven initiatives may be limited by lack of willingness from consumers to pay the extra cost. To investigate how this works out in practice, we compared broiler welfare requirements in five European countries, Denmark, Germany, United Kingdom, the Netherlands, and Sweden, in 2018, by means of the Benchmark method. A number of welfare dimensions, covering the input features typically modified in broiler welfare initiatives, were defined. A total of 27 academic welfare experts (response rate 75%) valued the different levels within each dimension on a 0-10 scale, and then weighted the relative contribution of each dimension to overall welfare on a 1-5 scale. By combining these values and weights with an inventory of existing welfare initiatives, the additional welfare generated by each initiative was calculated. Together with information on national coverage of each initiative, the Benchmark score for each country's production and consumption of chicken meat was calculated. Sweden achieved a much higher Benchmark for national production due to higher legal standards than any of the four other countries. The Netherlands, on the other hand, achieved a Benchmark for national consumption of chicken at the same level as that found in Sweden, because market driven initiatives complemented more welfare-limited Dutch legislation. So, despite some uncertainties in the Benchmark method, it appears that market driven initiatives can have a strong impact on improving broiler welfare, building on those standards achieved by animal welfare legislation.

    Market driven initiatives can improve broiler welfare – A comparison across five European countries based on the Benchmark method (URL)

    Benchmarking Farm Animal Welfare — A Novel Tool for Cross-Country Comparison Applied to Pig Production and Pork Consumption

    By P. Sandøe, H. O. Hansen, H. L. H. Rhode, H. Houe, C. Palmer, B. Forkman, T. Christensen (2020)
    Animals. MDPI


    A pluralist approach to farm animal welfare, combining animal welfare legislation with market-driven initiatives, has developed in many countries. To enable cross-country comparisons of pig welfare, a number of welfare dimensions, covering the features typically modified in legisla- tive and market-driven welfare initiatives aimed at pig production, were defined. Five academic welfare experts valued the different welfare states within each dimension on a 0–10 scale, then as- sessed the relative contribution of each dimension to overall welfare on a 1–5 scale. By combining these values and weights with an inventory of pig welfare initiatives in five countries, the additional welfare generated by each initiative was calculated. Together with information on the national cov- erage of each initiative, the Benchmark value for each country’s production and consumption of pork could be calculated on a scale from 0 to 100. Two (Sweden and the UK) had a much higher Benchmark value than the rest. However, there was a drop in the Benchmark for consumption in Sweden and the UK (indicating imports from countries with lower-Benchmark values for produc- tion). Even though the experts differed in the values and weights ascribed to different initiatives, they were largely in agreement in their ranking of the countries.

    Benchmarking Farm Animal Welfare — A Novel Tool for Cross-Country Comparison Applied to Pig Production and Pork Consumption (pdf)

    Benchmarking farm animal welfare – Ethical considerations when developing a tool for cross-country comparison

    By P. Sandøe, H. O. Hansen, H. H. Kristensen, T. Christensen, H. Houe & B. Forkman (2019) 
    Preprint version of a contribution to the EurSafe 2019 congress


    A tool enabling animal welfare to be benchmarked across countries would make it possible to monitor and compare the status of animal welfare at both disaggregated and aggregated levels. The results of the international benchmarking would be useful for a wide range of stakeholders taking a positive interest in farm animal welfare.

    We aim to build a model for pigs and chickens with the following elements: 1) For each type of animal production considered a number of parameters linked to housing and management are defined. The parameters relate to features of production that are modified in legislative and market-driven initiatives to improve welfare. 2) By means of assessments made either by consumers or by experts, each value of these parameters is assigned a weight. 3) In each countrythe welfare level (beyond the basic level defined by EU regulation) found in the production, or the consumption, of pork and chicken meat is calculated. 4) The total state of farm animal welfare across different forms of production (here only two forms) is calculated for each country.

    A number of ethical considerations must be addressed in the process of building the model. In the paper, we explain how we deal with the following considerations: The first concerns how to measure what affects animal welfare – whether the focus should be on environmental or outcome-based measures. Secondly, weights will need to be assigned to the different parameters, raising the question whether this should be done by animal welfare experts or consumers. Thirdly, it will be necessary to decide what to include for each country, and specifically whether it should be the welfare of animals produced in a country, including exports, or the amount of animal products consumed in the country, including imports. Fourthly, a decision will need to be taken on how to add welfare across pigs and chickens, and whether to count number of individuals, the volume of products or the value of products.

    Benchmarking farm animal welfare – Ethical considerations when developing a tool for cross-country comparison (pdf)








    Hornless cattle – is gene editing the best solution?

    Sandøe, P., Borchersen, S., Dean, W., Hyttel, P., Sørensen, L. P., & Palmer, C. (2021) 
    In H. Schübel, & I. Wallimann-Helmer (Eds.), Justice and food security in a changing climate: EurSafe 2021, Fribourg, Switzerland, 24-26 June 2021 (pp. 324-330). Wageningen Academic Publishers.


    Most dairy cows in Europe and the US have no horns. But this is mostly an artefact. Typically, the ability to grow horns is removed by means of so-called disbudding which, even when it is done with the use of local analgesia in combination with painkillers, may have long term negative effects on animal welfare. This suggests the need to seek alternatives. One alternative approach makes use of the genetic disposition not to grow horns (called polledness), which occurs naturally among domestic cattle but is not widespread within the typical dairy breeds. For economic reasons, the achievement of 100% polled dairy cattle through conventional breeding has a very long time-horizon. Gene-editing, most likely by using CRISPR-Cas 9, is an obvious alternative technique that has been shown to work. In this paper we consider whether using gene-editing is preferable to disbudding and conventional breeding from an ethical and a regulatory perspective. We discuss four kinds of ethical concerns: (1) naturalness; (2) respect for animal integrity; (3) animal and human welfare; and (4) human health and safety. Regarding (1) we argue that gene-edited cows are not significantly more unnatural than other modern cattle. Regarding (2) we argue that gene-edited individual cows are not disrespected. Regarding (3) we argue that there may be short-term significant negative effects on animal welfare, but that in the longer term there will be significant positive effects; and regarding (4) we argue that the well-being and safety of those working with the cattle is a strong argument in favour of polled cattle, while potential issues for consumer health are negligible. Our conclusion is that gene-editing dairy cattle for polledness seems to be a potentially acceptable and feasible solution. However, regulatory changes, either in the EU or in the US, will be required before the solution will work in practice. Recent developments in the US indicate that regulatory changes are very likely.

    Hornless cattle – is gene editing the best solution? (pdf)

    Transgenic livestock, ethical concerns and debate

    By M. Gjerris, R. Huber, J. Jesper, I.A.S. Olsson & P. Sandøe (2013)
    Encyclopedia of Sustainability Science and Technology. Springer 


    Glossary: Animal bioreactor Transgenic animal that produces recombinant proteins in its milk, egg white, blood, urine, or seminal plasma. - Antibody Protein produced as part of the immune reaction to render harmless a foreign substance (e.g., bacteria) entering the body of an organism. - Cloning (a) Production of exact copies (clones) of a gene/genes (gene cloning). The DNA strand containing the gene of interest is cut into suitably sized pieces (fragmentation) and the gene of interest is linked to a piece of DNA (cloning vector). This vector is then introduced into cells (transfection) which are cultured in vitro and then screened for the presence of the gene of interest. (b) Production of genetically identical organisms by somatic cell nuclear transfer (SCNT). It involves the introduction of the nucleus of a somatic cell from the organism to be cloned into an enucleated egg cell.

    Transgenic livestock, ethical concerns and debate (limited access)

    After Dolly - Ethical limits to the use of biotechnology on farm animals

    By J. Lassen, M. Gjerris & P.  Sandøe (2006)
    Theriogenology. Elsevier


    The cloning of Dolly the sheep gave rise to a widespread call for limits on interference with life. Until recently the main limits were technical: what it is possible to do. Now scientists are faced with ethical limits as well: what it is acceptable to do. In this context we take ethics to involve systematic and rational reflection on moral issues raised in the public sphere. The concerns of the general public are not necessarily valid, but they are the best point of departure if the discussion is to lead to a socially robust framework for setting limits to the use of animal biotechnology. To assess public understanding we examine two sources of data: Eurobarometer surveys from 1991 to 2002 and a qualitative interview study carried out in Denmark in 2000. Based on these sources, we formulate, and then discuss closely, the following concerns: dangers to human health and the environment, animal welfare, animal integrity, and usefulness. In the final part of the article it is proposed that a principle of proportionality should be the foundation for socially robust applications of animal biotechnology. Only in cases where the usefulness of the technology can be said to outweigh countervailing moral concerns, as in biomedical research, will applications of animal biotechnology stand up to scrutiny in the public sphere.

    After Dolly - Ethical limits to the use of biotechnology on farm animals (pdf)

    Breeding and biotechnology in farm animals - ethical issues

    By C. Gamborg & P. Sandøe (2003)
    Key issues in bioethics. A guide for teachers. Routledge Falmer


    Over the last century, and especially since the Second World War, animal production has become ever more efficient. Broiler chickens can grow to a weight of 2 kg in about five weeks, while 40 years ago it took twelve weeks to reach the same weight, and over the same period milk yields in most dairy cows have more than doubled. These achievements derive in part from improved management techniques, but to a large and still increasing extent they are the outcome of farm animal breeding, i.e. genetic improvement.

    Breeding and biotechnology in farm animals - ethical issues (pdf)























    Positive animal welfare: Bridging the gap or raising inequalities worldwide?

    Rault J-L, Sandøe P, Sonntag Q & Stuardo L (2022)
    Frontiers in Animal Science. Frontiers Media S. A.  


    Positive animal welfare (PAW) is a rising topic in animal welfare science, although its construct, definition, and operational approach remain debated. Despite this scientific uncertainty, there is societal interest to include more indicators of positive welfare in legislation, animal welfare assessment and accreditation schemes. Changes in some farming practices seem to be in line with promoting PAW (e.g., free-range housing), providing animals more opportunities for positive experiences such as rewarding natural behaviour, greater autonomy, or choice. Interestingly, some of the ideas underlying PAW are present in extensive production systems or low-input animal management practices that are common in low-income countries, for example free-roaming livestock or village dogs. Nevertheless, welfare challenges such as neglect, diseases, poor nutrition, animal abuse and other forms of suffering remain ubiquitous, especially where resources like veterinary support are limited. Living conditions for animals in low-income countries provide examples of the delicate balance between positive welfare and welfare risks relating to health and survival, with inextricable ethical dilemmas. In our view, the growing focus on PAW could stimulate a more balanced approach to animal welfare worldwide, promoting PAW while simultaneously limiting various forms of welfare challenges. However, this requires accounting for human factors such as societal and cultural location-specific aspects to find flexible solutions that also benefit and respect people whose livelihood may be at stake. Those human factors also modulate the consideration and importance of providing animals with positive welfare states and the role of underlying ethical concepts like happiness and “a good life.”

    Positive animal welfare: Bridging the gap or raising inequalities worldwide? (URL)

    What Is so Positive about Positive Animal Welfare? - A Critical Review of the Literature

    By A. B. Lawrence, B. Vigors & P. Sandøe (2019)
    Animals. MDPI


    It is claimed that positive animal welfare (PAW) developed over the last decade in reaction to animal welfare focusing too much on avoiding negatives. However, it remains unclear what PAW adds to the animal welfare literature and to what extent its ideas are new. Through a critical review of the PAW literature, we aim to separate different aspects of PAW and situate it in relation to the traditional animal welfare literature. We find that the core PAW literature is small (n = 10 papers) but links to wider areas of current research interest. The PAW literature is defined by four features: (1) positive emotions which is arguably the most widely acknowledged; (2) positive affective engagement which serves to functionally link positive emotions to goal-directed behavior; (3) quality of life which serves to situate PAW within the context of finding the right balance of positives over negatives; (4) happiness which brings a full life perspective to PAW. While the two first points are already part of welfare research going back decades, the two latter points could be linked to more recent research agendas concerning aggregation and how specific events may affect the ability of animals to make the best of their lives.

    What Is so Positive about Positive Animal Welfare? - A Critical Review of the Literature (pdf)