Perspectives in Dealing with Surplus Male Farm Animals

The selection of farm animals for single production goals has led to hybrids and breeds which are highly efficient but also largely specialized. In modern poultry production, for instance, broiler chickens are reared for meat production, whereas layer hybrids are kept for egg laying purposes. Similarly, specialized breeds for dairy or beef production are used by the cattle sector. In some regions of the world, goats are almost exclusively bred for milk production.

However, about half of all offspring will usually be male. Due to their specialization, male animals from strains selected for egg or milk production are not suitable for economic fattening purposes. Therefore, it is common practice to kill these animals directly after hatch or birth, or - sometimes in the case of male calves - to keep them for a short period of time at the lowest costs possible until slaughter. This routine killing of young, healthy animals without prior intention of carcass use is often regarded as unavoidable side effect of a particular line of livestock production. The practice might not be a welfare issue for the respective animals per se, provided the killing is performed humanely and state-of-the-art. However, there are several welfare risks, for instance the application of inadequate killing methods or the treatment of the animals before killing, particularly since they lack economic value. In addition, the killing of surplus male livestock raises moral concerns as the animal is seen as unwanted “by-product” or waste, which disrespects its intrinsic value. Although some of the carcasses may be used as animal feed, this is rather an afterthought than an initial intention, and might not contribute to the acceptance of the practice.
Therefore, alternatives have to be developed either for avoiding the production of surplus male animals or their killing without intentional use. Such alternatives may include novel breeding or selection methods, the use of less specialized breeds which may have additional advantages, such as improved resilience, or rearing animals for special markets. The goal is to provide science-based approaches for tackling the issue and moving towards welfare friendly, socially accepted, and thus sustainable livestock farming practices.

This Research Topic aims to present a collection of Original Research articles and Reviews on novel or alternative approaches tackling the issue of killing surplus male production animals. Perspectives and Mini-Reviews may also be considered. Contributions should focus on reducing the numbers of unwanted male offspring or avoiding the need to routinely kill these animals without prior intended purpose. Topics of interest are for instance: the investigation or application of selection methods, such as using sexed sperm, dual-purpose breeds or hybrids, of which animals of both sexes gain economic value, or rearing surplus males to high welfare standards for special niche markets. These themes may also be addressed from a socio-ethical perspective, for instance by investigating the perceptions, concerns or claims of the different stakeholders involved, or by reflecting on these with the help of ethical theories.