Oviposition time, flock age, and egg position in clutch in relation to brown eggshell color in laying hens.

In Australia and other parts of the world, table eggs with uniform brown eggshell color are well regarded by consumers. Brown eggshell color has been positively correlated with certain egg characteristics such as shell strength and egg specific gravity, along with specific antibacterial functions. In the current study, the effect of hen oviposition time, flock age, and egg position in-clutch on the intensity of brown eggshell color was studied in commercial laying hens. The collected eggs were processed to measure egg weight, shell reflectivity, shell color (L*a*b*), quantification of protoporphyrin IX (PP IX), and shell thickness. Hen oviposition time had a statistically significant effect (P < 0.05) on egg weight, L*a*b*, amount of PP IX, and shell thickness. L* increased from 59.72 in the first half hour after lights on to 61.67 6 hours later, and PP IX per gram of eggshell decreased from 1.32×10(-7) mM to 1.26×10(-7) mM. Flock age had a significant effect on egg weight, L*a*b*, shell reflectivity, PP IX, and shell thickness. The mean egg weight increased from 55.4 g at 25 wk of flock age to 63.3 g at 75 wk of flock age. PP IX per gram of eggshell was 1.45×10(-7) mM at 25 wk and declined to 1.31×10(-7) mM at 75 wk of flock age. Individual hen clutch length was highly variable, ranging from 22 to 123 eggs in a single clutch. Egg position in a clutch had a significant effect on all egg quality variables measured; however, the R(2) values for each variable measured were low. The eggshell color declined to a greater extent with increasing position in a clutch for long clutches compared with short and medium clutches. In conclusion, hen oviposition time affected brown eggshell color with darker brown eggs laid early in the d and lighter colored brown eggs laid later in the morning. The intensity of brown color decreased with flock age, and egg position in-clutch had relatively little effect on brown eggshell color.

Eggshell color in brown-egg laying hens - a review.

The major pigment in eggshells of brown-egg laying hens is protoporphyrin IX, but traces of biliverdin and its zinc chelates are also present. The pigment appears to be synthesized in the shell gland. The protoporphyrin IX synthetic pathway is well defined, but precisely where and how it is synthesized in the shell gland of the brown-egg laying hen is still ambiguous. The pigment is deposited onto all shell layers including the shell membranes, but most of it is concentrated in the outermost layer of the calcareous shell and in the cuticle. Recently, the genes that are involved in pigment synthesis have been identified, but the genetic control of synthesis and deposition of brown pigment in the commercial laying hen is not fully understood. The brown coloration of the shell is an important shell quality parameter and has a positive influence on consumer preference. The extent of pigment deposition is influenced by the housing system, hen age, hen strain, diet, stressors, and certain diseases such as infectious bronchitis. In this article, the physiological and biochemical characteristics of the brown pigment in commercial brown-egg layers are reviewed in relation to its various functions in the poultry industry.

The location of protoporphyrin in the eggshell of brown-shelled eggs.

Protoporphyrin has been identified as the main eggshell pigment in brown-shelled eggs. However, there has been some uncertainty concerning the distribution of the pigment within the shell (and cuticle) in brown-shelled eggs. Most previous studies have suggested that the bulk of the shell pigment is deposited in the cuticle of the shell. The present study measured the levels of protoporphyrin in intact eggshells and in shells from which the cuticle had been removed, using eggs from flocks at 3 different ages. This enabled the calculation of the relative amount of protoporphyrin in the calcareous eggshell and the cuticle layer of the eggshell. The majority of the protoporphyrin pigment was located in the calcareous part of the eggshell (80-87%) with a minority contained within the cuticle (13-20%). These findings suggest that studies focused on maintenance of shell color in brown-shelled eggs need to consider the stage of egg formation at which the reduction in pigment deposition is occurring.

Significance of serum inhibin in female infertility.

BACKGROUND: Serum inhibin, a glycoprotein hormone is secreted from granulosa cells in females and has been shown to suppress secretions of FSH from pituitary. METHODS: A total of 45 women, 30 infertile subjects and 15 age matched fertile controls were included in this study. Blood samples from each subject were collected during follicular and luteal phases separately and were tested for serum inhibin levels using an enzyme linked immunosorbent assay (ELISA). RESULTS: Serum inhibin concentration of infertile subjects during follicular phase was 35.5 +/- 22.94 pg/ml and luteal phase was 32.4 +/- 24.2 pg/ml. Whereas serum inhibin level in follicular phase was 10.39 +/- 2.03 pg/ml and luteal phase was 12.78 +/- 6.86 pg/ml of the fertile subjects. Serum inhibin was significantly raised in the infertile subjects as compared to the fertile subjects (P < 0.05). However serum inhibin concentration during the follicular and luteal phases of the infertile subjects was not significantly different (P > 0.05). CONCLUSION: It is thus concluded that increased serum inhibin level may be treated as sensitive and early index of declining ovarian function.