Description of the physical characteristics of the eggs from creole hens and commercial eggs : Description of the egg from creole hens and commercial eggs

Resumen

Objective: to compare the external and internal physical characteristics and yolk color of eggs with white, brown or blue shells from creole hens, and the commercial eggs with white and brown shells from hens bred in layer-farms, which are sold in the region of Mezquital Valley (Hidalgo), Mexico.

Design/ Methodology/ Approach: eggs from creole hens were collected in traditional markets (called tianguis in Mexico) customarily placed in the Mezquital Valley (Hidalgo), Mexico. The colors of the shell were blue (n = 100), white (n = 100), brown (n = 100), in addition, pieces of eggs with white shell (n = 100) and brown shell (n = 100) were purchased in retailer stores. In those stores no eggs with blue shells were found. Variables evaluated in the eggs were weight, area, volume, shape index, length and width, whites and yolk weight; also, color intensity of the yolk was evaluated with the DSM™ Yolk color fan.

Results: the blue egg in this study presented (p ≤ 0.05) the highest weight (61 vs 53, ± 0.66 g), area (72 vs 65, ± 0.67 cm²) and volume (56 vs 48, ± 0.60 cm³) compared to the creole white egg. Creole brown egg, as well as commercial white and commercial brown eggs had a similar shape index (78, 79 and 77, ± 0.65 %). Egg length was also similar; no significant differences were found (p > 0.05). However, the creole white egg had the smallest egg width compared to the other types of egg. The blue egg had the highest weight of whites, and the creole white egg the lowest, compared to the other types of egg (36 vs 30, ± 0.51g). Creole blue, commercial white and commercial brown eggs had similar yolk weight (19, 18 and 18, ±0.52 g). The commercial white and commercial brown eggs had the highest color intensity in the yolk (10.3 and 11.3, ±0.15 DSM™ Yolk color fan), whereas the creole white egg had the least colorful yolk (7.4 ±0.15 DSM™ Yolk color fan).

Limitations/ Implications of the study: backyard poultry farming in the state of Hidalgo is limited by the loss of rural areas and creole hens are displaced by commercial breeds.

Findings/ Conclusions: the blue egg from backyard creole hens was larger than the commercial egg, while the creole white egg was the smallest. However, this characteristic does not affect nutritional quality. Commercial white egg and commercial brown egg had the highest color intensity in the yolk. The color of the yolk is due to the carotenoids present in the yolk that are beneficial for human health.