In certain markets, synthetic pigments that enhance yolk color are banned, whereas in others, there is an increasing niche market for eggs produced using natural pigments. Nettle (Urtica dioica) has been shown to be an effective pigmenting agent in broilers giving a rich yellow skin. As such, it was considered interesting to test nettle as a potential natural yolk pigment. Thus, a four-week trial was conducted using 40 individually caged H&N Nick Brown layers (70 weeks of age), not only to test the effectiveness of nettle pigmentation, but also to investigate any possible side effects on performance, egg quality and antioxidant status.
A basal diet, low in pigments and tocopherols, was supplemented with 0, 6.25, 12.5 or 25 g nettle per kg feed. In addition, positive control diet was used containing synthetic pigments. Results indicated that yolk yellowness increased with nettle addition and this was as effective as synthetic pigmentation. Due to the lack of red pigments in nettle, scores were lower in this regard compared with the positive control treatment which contained a red pigment. Furthermore, nettle supplementation did not affect laying performance and general egg quality, thus making nettle an effective natural pigment. It should be noted, however, the authors (Y. Loetscher, M. Kreuzeremail, R.E. Messikommer, "Utility of nettle (Urtica dioica) in layer diets as a natural yellow colorant for egg yolk") indicated that batch can be an unpredictable variable when sourcing nettle for pigmenting purposes.