Changes in pigment, spectral transmission and element content of pink chicken eggshells with different pigment intensity during incubation

Abstract

Objective. The objective of this study was to investigate changes in pigment, spectral transmission and element content of chicken eggshells with different intensities of pink pigment during the incubation period. We also investigated the effects of the region (small pole, equator and large pole) and pink pigment intensity of the chicken eggshell on the percent transmission of light passing through the chicken eggshells. Method. Eggs of comparable weight from a meat-type breeder (Meihuang) were used, and divided based on three levels of pink pigment (light, medium and dark) in the eggshells. During the incubation (0-21 d), the values of the eggshell pigment (ΔE, L (∗), a (∗), b (∗)) were measured. The percent transmission of light for different regions and intensities of eggshell pigmentation was measured by using the visible wavelength range of 380-780 nm. Result. Three measured indicators of eggshell color, ΔE, L (∗) and a (∗), did not change significantly during incubation. Compared with other regions and pigment intensities, eggshell at the small pole and with light pigmentation intensity showed the highest percent transmission of light. The transmission value varied significantly (P < 0.001) with incubation time. The element analysis of eggshells with different levels of pink pigment showed that the potassium content of the eggshells for all pigment levels decreased significantly during incubation. Conclusion. In summary, pigment intensity and the region of the eggshell influenced the percent transmission of light of eggshell. Differences in the spectral characteristics of different eggshells may influence the effects of photostimulation during the incubation of eggs. All of these results will be applicable for perfecting the design of light intensity for lighted incubation to improve productivity.

Keywords: Chicken eggshell; Element content; Light; Percent transmittance; Pink pigment.

Figure 1. The schematic of the detection equipment for light transmission.

Figure 2. The PT of light over the wavelength range of 380–780 nm at the small pole, the equator and the large pole of pink pigment eggshells on days 0 during incubation.

S, small pole; E, equator; and L, large pole. (A) shows the PT of light over the wavelength range of 380–780 nm at the small pole, the equator and the large pole of pink pigment eggshells on days 0 during incubation. (B) shows the mean PT value of eggshell over the wavelength range of 380–780 nm.

Figure 3. The PT of light over the wavelength range of 380 to 780 nm for the light, middle and dark levels of pink pigment in eggshells on day 0 during the incubation.

LIP (L), light intensity pigment; MIP(M), medium intensity pigment and DIP(D), dark. (A) shows the PT of light over the wavelength range of 380 to 780 nm for the light, middle and dark levels of pink pigment in eggshells on day 0 during the incubation. (B) shows the mean PT value of eggshell over the wavelength range of 380 to 780 nm.

Figure 4. The PT(%) of light over the wavelengths of 380–780 nm at different regions of the eggshell and at different levels of intensity of the pink pigment of the eggshells at different periods during incubation.

Values are the mean ± SEM, n = 30.

Figure 5. The thickness of eggshell on days 0, 4, 8, 12,16 and 21 during the incubation.

If followed by different superscripts, values are significantly different (P < 0.05). Data were presented as mean ± SEM, n = 30.