The data were analyzed using Statistical Package for the Social Sciences (SPSS, version 23). Descriptive analysis was performed on the sociodemographic information of the respondents. We noticed a high number of women with a high education level originating from two specific provinces out of 12 provinces in the Netherlands as can be seen in Table 2A. The data were divided into two subsets (Tables 2A,B), so that any statistical analysis would not be wrongly attributed to the large group of highly educated women (HEW). That is, more than half of the respondents were HEW, subset 1 (n = 143). Subset 2 contained the rest of the respondents (REST: n = 86). Our aim was not to compare subsets but to limit incorrect conclusions on demographics as a consequence of the background of HEW skewing the dataset. In order to have an equal number of respondents in specific categories, we combined provinces together as follows: South NL: Limburg and Noord-Brabant; Urban South-West: Noord-Holland and Zuid-Holland; North NL: Overijssel, Drenthe, and Groningen. The same was done for age group 51–60 and 60+ in subset 1. We excluded one respondent below 17 years old and two in the category 17–21 due to low sample sizes.

First, descriptive analysis on knowledge levels of the Dutch poultry industry (true/false answer options for part 1) was performed. Likert scale data were analyzed as frequencies of respondents adding agree + strongly agree and adding disagree + strongly disagree together and comparing these frequencies with a chi-square test. Change in acceptability of CMC was calculated for the subsets by comparing the response to the first and second questions on acceptability (in the beginning and at the end of the survey). To test which alternative was preferred, the overall percentage of first preference was calculated and analyzed with a chi-square test. The relative importance of the factors influencing choice of product was assessed with a Wilcoxon signed rank test. The WTP for eggs and for meat without CMC was assessed with a Wilcoxon rank sum test. A chi-square test was used to determine whether income levels were affecting the price respondent were willing to pay for eggs and for meat with or without CMC.

For both subsets, roughly 52% knew about the practice of CMC (Figure 1). The majority of respondents were aware that culled chicks are used as animal food (HEW: 74.8%; REST: 79.1%). Roughly half of the respondents knew about the method of culling (HEW: 50.3%; REST: 58.1%) and that only male layer chicks are culled and not male broiler chicks (HEW: 44.8%; REST: 47.7%). The majority of respondents knew that sex determination of chicks takes place after hatch (HEW: 73%; REST: 65%) by a specialist (HEW: 74%; REST: 64%). Regarding the general knowledge on the Dutch poultry industry, <50% of the respondents answered all questions correctly (HEW: 34.4%; REST: 32.6%). The most incorrect answers were given on the question regarding the chicken population in the Netherlands (HEW: 37.1% and 46.5%).

See Table 3 for mean and median levels of the respondents' acceptance levels on 10 statements regarding CMC. All five questions regarding accepting the practice of CMC were disagreed (1) or strongly disagreed (2) (min–max mean levels: HEW: 1.72–2.02; REST 2.13–2.45). This was also significantly shown by the percentage of respondents disagreeing with CMC in HEW (78.8%) and REST subset (67.3%), X² = 3.65, P = 0.05. A smaller percentage of respondents disagreed with CMC as unavoidable (HEW: 44.8%; REST: 26.7%; X² = 7.03, P < 0.001). Keeping chickens for food tended to be accepted based on high Likert scale levels (1 = strongly disagree, 5 = strongly agree: HEW: 3.52; REST: 3.92). Roughly half of the respondents agreed with keeping chicken for food production (51%: HEW; 45.3% REST). Very high levels of agreement were seen regarding finding an alternative for CMC (HEW: 4.49; REST: 4.22), with highest levels of acceptance for in-ovo sex determination (3.85 for both subsets).

For both subsets, the percentage of respondents who disagreed with the practice of CMC increased, although not significantly (X² = 1.55, NS; Figure 2). At the start of the survey, for HEW, 40.6% strongly disagreed to accepting CMC vs. 45.5% after the survey. At the start of the survey, for REST, 27.9% strongly disagreed with accepting CMC vs. 33.7% after the survey.

Respondents were asked to arrange the alternatives to CMC in order of preference. The majority of the respondents chose in ovo sex determination as first preference as alternative to CMC (HEW: 57%; REST: 51%; Figure 3), followed by keeping dual-purpose breeds (HEW: 29%; REST: 23%). Rearing layer males were scored the least as first preference (HEW: 6%; REST: 10%), even lower than keeping the current situation (HEW: 8%; REST: 16%). For effects due to income, education level, awareness, and change in acceptability, see Table 4. More respondents with a higher level of awareness (X² = 15.08, P < 0.05) and higher income (X² = 19.15, P < 0.05) chose in-ovo sex determination as first preference.

The most important factor for choice of alternatives for CMC is food safety in both subsets, followed by animal friendliness, the environment, naturalness, taste, feasibility, availability of the product, and price (Table 5; HEW: X² = 273.7, P = 0.000; REST: X² = 152.03, P = 0.000). No relationship was found between whether price was the most important factor and income level (HEW: X² = 15.89; REST: X² = 27.9, NS).

WTP more for eggs without CMC was seen in 41.9% of respondents vs. 45.3% who is willing to pay equal to the general costs for 10 eggs. There is a significant difference in WTP for the general costs for 10 eggs and the extra costs for 10 eggs without CMC (REST: Z = −4.134, P = 0.000). In the HEW, respondents were willing to pay more for 10 eggs without CMC (Z = −7.368, P = 0.000). Here, 62.9% of HEW are willing to pay more for eggs without any culling, whereas 26.6% are willing to pay equal to the general costs for 10 eggs. Only 10.5% of HEW and 12.8% of the remaining respondents are not willing to pay more for eggs without any culling.

In both subsets, a large group of respondents answered not applicable to the question WTP cockerel burgers (HEW: 43%; REST: 39%), see Figure 4. Of this N/A group, 77% had a special diet in HEW, and 52.9% in REST. WTP (and effects of income levels) was, therefore, only assessed for the remaining respondents. The WTP for two cockerel meat burgers was €3.50 in HEW (21.7%; mean: 4.07; median: 4.00) and €4.50 in REST (18.6%; mean: 3.86; median: 4.00). The set price for cockerel burgers was €2.50, indicating WTP 1 or 2 € on top of the original price. Income levels did not affect respondents' WTP for 10 eggs with or without culling for both subsets (HEW: general cost: X₂ = 22.064; NS, no culling: X₂ = 17.390, NS, and REST: general cost: X₂ = 19.78, NS; no culling: X₂ = 24.097, NS). No relationship was seen between income level and the WTP for cockerel meat in both subsets (HEW: X₂ = 16.533, NS; REST: X₂ = 16.625, NS). WTP for cockerel meat was affected by whether the product contained a label “produced without CMC” (HEW: X² = 48.17, P = 0.03; REST: X² = 22.25, P < 0.05). No relationship was found between income level and WTP for cockerel meat (HEW: X² = 16.53, NS; REST: X² = 16.63, NS).

When comparing our results with other surveys on CMC (Table 6), we note that the percentage of respondents being aware of CMC was similar to the Dutch study in 2015 (52 vs. 55%) but lower to a German study in 2016 (70%) and higher than the Dutch study in 2011 (42%) and a Swiss study (25%). Percentage of respondents not accepting CMC or indicated that there is a need for an alternative to CMC was relatively high (67.3–78.8%) compared to the previous Dutch studies in 2011 (58%) and 2015 (47%). In a recent German study with 482 respondents, a need for an alternative was chosen by 89%. No direct comparison could be made between studies regarding preferences for alternatives to CMC, as the presented alternatives slightly differed, i.e., more information on in ovo techniques was given (39) or the focus was on dual-purpose chicken (10, 40), and rearing male layers was not included (9, 10, 39, 40). However, in-ovo sex determination as an alternative to CMC was preferred in more than 50% of our respondents, which was higher than in any other study except for a study in Germany in 2018 (75%).

The data cannot be seen as representing the Dutch population. Due to this limitation, we have been careful not to overinterpret the sociodemographic aspects of our results. For both subsets, we had an underrepresentation of people with a low income and an overrepresentation of participants from the provinces of Utrecht and Gelderland, which was likely to be because we used personal connections of the authors for our survey. For the future, distribution via other sources is recommended [i.e., via egg producers (10), survey companies (9, 36), at supermarkets (40)] to obtain a more balanced view of the Dutch population and their buying habits. However, even though respondents do not represent the Dutch population, and subset REST was more diverse than subset HEW, and the result of both subsets were overall very similar. It appears that our respondents fit the targeted consumer class of “Price-insensitive In-Ovo supporters” (10, 38) as cost (WTP) was the least important factor for choice of alternatives to CMC. Our results should be a trigger to do further research on this topic in a broader range of the Dutch society to include other classes of consumers (10, 38). The setup of our study could be used in future surveys on CMC by giving insight on which factors to include, i.e., provide information on the poultry industry and including more elaborate information on the alternatives with regard to sustainability and economics.

A further explanation for the skewed respondents' background might be due to the topic of the questionnaire and the ethical issues it raises. People may feel uneasy knowing that the CMC takes place for the production of eggs and prefer to remain blind to the subject [i.e., a moral lock-in; (31)]. This might explain the high number of respondents initially starting the questionnaire but not finishing it (259 out of 372).

Our study showed comparable awareness levels (52%) as in other studies in the Netherlands in 2018 [55%; (36)] and 2011 [55%; (9)] but higher than in Switzerland [25%; (40)], see Table 6. Awareness and disapproval of CMC show an increase in several EU countries (36). Highest awareness levels were found in the provinces where most chicken farms are present in the Netherlands¹. The rise in awareness from 2011 to 2018 in the Netherlands was accredited to media attention in 2013 caused by a study commissioned by The Dutch State Secretary of Agriculture on public views on alternatives for CMC (36). In France and Germany, a rise in public awareness on CMC likely caused pressure to ban CMC and seek viable alternatives.

A very high percentage of our respondents agreed that an alternative to CMC is needed. Keeping the current situation was also less preferred as opposed to a study in 2018, where 28% chose keeping CMC (36). The first choice for an alternative for CMC was in-ovo sex determination, by 57% of the respondents, which is higher than that in other studies (9, 36). In our study, we only looked at alternatives that are available on the Dutch market and did not distinguish between types of in-ovo sexing techniques and at which embryonic stage the in-ovo technique is applied (3) as Leenstra et al. (9) did. They showed that in-ovo sex determination was most preferable, but only on non-incubated eggs. With this method, the sex of the embryo is determined in the fresh egg, and male eggs are excluded from incubation as opposed to determining the sex of the embryo in incubated eggs during early or late development (9). An aspect to consider in in-ovo sex determination that people may choose or not choose this alternative to CMC is at what age it takes place (39, 42, 43). Studies on neural development of chick embryos (44, 45) indicate that afferent nerves develop around day 4 of incubation and that the synaptic connection via the spinal cord is not present before day 7 of incubation, which make nociception impossible prior to this stage. At what age in-ovo sex determination is performed should be included (and explained in the survey), as it does influence respondents' attitude to in-ovo sexing (38). In another study in Dutch citizens, in-ovo sex determination was only accepted by 11% of respondents (36). In Switzerland, no difference was found between in-ovo sexing and keeping dual-purpose chicken as an alternative to CMC (40). An informed decision for an alternative requires knowledge of the pros and cons of the alternative and the current practice (9). Underlying social norms and values may overrule the initial choice (10) for an alternative. At the same time, when more information is provided about the alternatives, the decision for one or the other may not be so easy (9). Zoll et al. (11) developed a decision support tool for the case of a dual-purpose alternative to CMC in Germany, which could be used when targeting the Dutch society. Based on our outcome and the results of surveys in the past in the Netherlands and other EU countries, it appears that the majority of participants in these studies respond to the knowledge on CMC by disagreement and are strongly in favor of an alternative to CMC.

Based on our results, the respondents indicated that at this point in time, in ovo sex determination is more likely to be chosen as an alternative to CMC over rearing male layers and keeping dual-purpose chickens. It should be noted that aspects of sustainability and economics were absent specifically from our study, and that the choice of alternative should be under the highest level of welfare. Studies on keeping layer males (15) or dual-purpose chicken (13, 46, 47) are relatively scarce and require more investigation as to whether and how these cockerels can be kept under high as there might be issues with aggression (48).

Economic incentives are needed to pursue this avenue also with respect to sustainability issues since it takes longer to raise cockerels, which require more food and other costs, as opposed to broiler chicken. In Thailand, layer males are kept for 60 days to achieve a body weight of 0.8–1.2 kg (49). In a growing world population where broiler chicken meat production is more sustainable than other sources of animal protein, it makes the choice for other—less profitable (50, 51)—chicken meat difficult. Additionally, the meat of layer cockerels has a different texture and taste from those of broiler meat (52). In Asia and Africa, however, meat of cockerels of layers and native chicken is very popular (53, 54).

Respondents were willing to pay [willingness to pay (WTP)] more for eggs without CMC involved even above the current price for existing CMC-free eggs [Kipster® (www.kipster.nl: keeping male layers for meat products); Respeggt (www.respeggt.com: in-ovo sex determination and exclusion of male embryos for further development)]. Price per egg on the Dutch market varies by type of farming system the hens are kept as well as the type of hen (i.e., brown or white). The price of eggs fluctuates due to seasonal changes, demand and supply, and legal restrictions (i.e., keeping hens indoors during bird flu). At present, the price per egg (approximation over different Dutch supermarkets; 2021) from white barn layers is €0.16, from brown barn layers is €0.20, free-range white or brown layers is €0.29 and for organic layers is €0.45. Currently, Dutch Kipster eggs are sold (at a specific supermarket) for €0.25 per egg and German Respeggt eggs are being sold for €0.39 per egg. Most of the respondents who consumed eggs were WTP at least or more than €0.35 per egg without CMC. This is consistent with earlier studies, showing that 50–60% of respondents were WTP 5–10 cents more per egg (9). Although our respondents were less inclined to buy processed poultry meat products, they are WTP at least €3.50 for two processed cockerel burgers, 1€ more than the current price of cockerel burgers in the Netherlands. However, it should be mentioned that a large percentage of our respondents (HEW: 28.7%; REST: 36.0%) had a relatively high income (>€50.000, income levels were similar to those by Dutch statistical database; statline.nl), which may have skewed this result. Furthermore, no relationship was found between the importance of price and income level. This also supports the aforementioned idea that our respondents who buy meat and eggs fit within the “Price-insensitive In Ovo supporters”—a specific class of consumers, and the results should be viewed as biased toward this type of consumers (38). We did not ask how often meat or eggs are bought as done by Gangnat et al. (40) and Busse et al. (10), and thus, we cannot fully assess the motives of our respondents, and further research is needed to understand which factors influence choice for specific poultry products. One issue in surveys is whether the WTP given is the real WTP of consumers (55), i.e., the price people indicate to pay and the real price they are paying. Therefore, future research on this topic should include indirect measures of WTP and estimate a hypothetical bias that is higher for niche products, such as eggs without CMC and cockerel meat.

The most important factor when buying poultry meat or eggs was food safety, similar to a study of the Dutch public in 2018 (36). Interestingly, this was not the first factor in earlier studies on the alternative for CMC under the Dutch public (9). All three studies [this study, (36), and (9)] have animal friendliness as an important factor for choice of alternative for CMC. In the study by Leenstra et al. (9), animal friendliness was the most important factor. Likely due to the provision of more in-depth understanding of the topic (i.e., by a film and focus group), respondents could make a better assessment on the factors of importance for this type of animal-based product. The image of culling day-old chicks may have also further shocked participants in that study, as it did regarding information on CMC in the survey in Switzerland (40). Naturalness was an important factor in alternatives to CMC (9) and when accepting specific foods and certain technologies involving food production (56). This aspect is consistent across countries and years, indicating that it might be one of the most important factors to include when promoting CMC-free food products. We did not explain or define naturalness and whether this factor is excluding or including aspects such as animal welfare and the environment. In future surveys, the definition of naturalness should be provided either by the respondents (i.e., in a preliminary questionnaire) or given by the survey makers.

Our results showed that providing respondents with information on the poultry industry decreased the level of accepting CMC, i.e., more disagreement after the questionnaire than before. This was comparable to Swiss consumers, who were more WTP when they knew more about the poultry industry (40), which is stipulated as important to make an informed choice in this matter (9). In our study, labels were preferred so as to make a choice for CMC-free products easier. These results were also found in other studies where labels were recommended (40). Pictures may provide shocking images but could also be helpful in communicating the essential ethical elements of CMC (57) and the process of in-ovo sex determination techniques in detail to establish a higher WTP (58).