Current approaches to avoid the culling of day-old male chicks in the layer industry, with special reference to spectroscopic methods

Abstract

The negative correlation between fattening and laying performance prevents breeding improvement in both laying performance and meat yield. Therefore, specialized chicken lines have been bred in order to achieve either an efficient production of high-quality eggs or high growth rates. As a result, day-old male chicks are culled in the layer hatchery, which poses animal welfare and ethical problems. Breeding companies, scientific groups, and hatcheries are attempting to resolve this issue, with a common aim to find feasible alternatives for the routine killing of male layer chicks. Some approaches aim to influence the sex ratio, while others target at the economically feasible use of the male layer offspring, such as the fattening of "laying hen brothers" or crossbreedings of layers and broilers to create "dual-purpose chickens." Another approach is the sex determination prior to hatch. One of the prerequisites of in ovo sex determination is a practicable method that can be used in industry. The analysis needs to be rapid, cost-efficient, and highly precise; in addition, negative impacts on hatching rate, animal health, and/or performance parameters should be limited. Furthermore, sex determination should be performed before the sensory nervous system's response of the chick embryo to certain or potentially harmful stimuli is developed, which according to current knowledge is before the d 7 of incubation.

Growth Performance of Local Chicken Breeds, a High-Performance Genotype and Their Crosses Fed with Regional Faba Beans to Replace Soy

“…Since the genetic correlation between growth rate and egg production is negative, in commercial poultry farming, predominantly crosses of specialized lines are used that have been selected either for a high laying performance or for a high growth rate and muscularity [1]. Therefore, in the layer industry the male chicks of layer hybrids are culled on the first day of life because of their low fattening performance.…”

“…In Germany alone this accounts for more than 42 million chicks per year, given a sex ratio of 50% females and 50% males [2], which is problematic in terms of animal welfare, legal and ethical aspects, and social acceptance. In addition to methods of sex determination "in ovo", which are currently under development, and extended laying periods [1,3], fattening of male layer chicks is considered to be a possibility for overcoming the killing of day-old chicks. In this context, the fattening of male chickens up to a maximum weight of 650 g, then called poussins [4], the fattening of the cocks of heavy layer hybrids or the use of dual-purpose-breeds [5,6] have been examined.…”

Ethical Concerns in Poultry Production: A German Consumer Survey About Dual Purpose Chickens

“…In ovo sexing and fattening of "lay hen brothers" are seen as potential economically viable solutions because they build on conventional hybrid breeds and established market structures. In ovo sexing refers to determining the sex of fresh eggs to sort out male eggs (Krautwald-Junghanns et al 2018;Galli et al 2017;Kaleta and Redmann 2008). The fattening of "lay hen brothers" deals with rearing layer-variety male chicks of conventional hybrid breeds for meat (Krautwald-Junghanns et al 2018;Bruijnis et al 2015).…”

“…In ovo sexing refers to determining the sex of fresh eggs to sort out male eggs (Krautwald-Junghanns et al 2018;Galli et al 2017;Kaleta and Redmann 2008). The fattening of "lay hen brothers" deals with rearing layer-variety male chicks of conventional hybrid breeds for meat (Krautwald-Junghanns et al 2018;Bruijnis et al 2015). Whereas in ovo sexing is still in its infancy, fattening male chicks is an increasingly disseminated agricultural practice.…”

Integrating Sustainability Goals in Innovation Processes: Applying a Decision Support Tool in a Dual-Purpose Chicken Case Study

“…Eggs that are developing into male chickens are destroyed, preferably before embryonic development starts. However, the respective technology has not been fully developed [20,21]. Another alternative practice is the use of dual-purpose chicken breeds that are suitable for the production of both eggs and meat, but the production costs are higher compared to those of specialized layer hens and broiler chickens [19].…”