The assessment of viscosity measurements on the albumen of consumption eggs as an indicator for freshness.

Viscosity values of albumen reported in the literature are difficult to compare because different shear rates and different methods of sample preparation have been adopted. Therefore, we first investigated the effect of shear rate on the viscosity measurements of thick albumen. For intact albumen, a large intersample fluctuation in viscosity with increasing shear rate was observed. Furthermore, a large hysteresis effect was observed, indicating that the structural properties were substantially altered by the rotational behavior of the rotor. From this, we concluded that to obtain reliable measurements, the albumen needed to be mixed. After mixing, a smooth evolution in viscosity with increasing shear rate was observed. Compared with intact albumen, the hysteresis effect was smaller but still present. We next investigated the correlation between albumen viscosity and Haugh units. For this, we compared the viscosity of fresh eggs with the viscosity of eggs stored for 24 d at a temperature of 18°C. The Haugh units were first determined, and the viscosity was next determined on mixed albumen at a shear rate of 200 rad/s. Mean viscosity equaled 0.0304 and 0.0181 Pa/s for fresh eggs and eggs stored for 24 d, respectively. The decrease in viscosity during storage was significant (α = 0.05). Furthermore, we observed that the correlation between Haugh units and viscosity measured on the same egg was low. Fresh eggs having comparable Haugh units differed substantially in their measured viscosities, whereas for stored eggs, the Haugh units differed substantially but the viscosities were comparable. It is unlikely that the very large variation in rheological properties observed among fresh eggs reflects the natural variation in albumen freshness present after lay. Results suggest that these differences were partly due to the structural changes caused by albumen sampling and by the turning motion of the rotor. We conclude that determination of the rheological properties of albumen is practically infeasible and that albumen viscosity cannot be used as an index for albumen freshness.

Albumen freshness assessment by combining visible near-infrared transmission and low-resolution proton nuclear magnetic resonance spectroscopy.

Recently, some nondestructive methods for the assessment of albumen freshness were developed. Among others, visible near-infrared transmission spectroscopy and low-resolution proton nuclear magnetic resonance (LR (1)H NMR) measurements were proposed. This study was performed to evaluate the potential of the combined measurement of visible near-infrared transmission spectroscopy and LR (1)H NMR measurements for the assessment of albumen freshness. Our results show that solely based on the transmission measurements, a good estimation of albumen freshness can be achieved. Based on LR (1)H NMR measurements, an estimation of albumen freshness can be achieved if larger egg collectives are used. However, when individual eggs are considered, only a moderate estimation is feasible. Finally, it was observed that combining both spectroscopic techniques did not improve the assessment of albumen freshness when compared solely to transmission measurements.

Semiautonomous development of the extraembryonic membranes in the chicken embryo.

Based on an old paradigm that the extra-embryonic membranes develop semiautonomously from the embryo, it can also be postulated that subembryonic fluid (SEF) will be formed semiautonomously against embryonic growth, because the formation of SEF is mediated by the yolk sac membrane. In this study, we interfered in the development of SEF or the embryo. The acoustic resonance technique (which measures the resonant frequency of an excited egg) was used as a nondestructive tool to monitor the development of SEF. In the first experiment, in which the embryo was killed chemically with NaN3, it was proven that the formation of SEF continued, even when the embryo was killed after the initiation of the growth of the yolk sac membrane. In the second experiment, in which the development of SEF was inhibited chemically with amiloride, it was shown that the embryo developed further, although SEF formation was inhibited. In the last experiment, it was shown that the age of the flock affected the development of the embryo and the sudden decrease of the resonant frequency in a different way. However, some presetting conditions, such as storage, may affect both in a similar way. Our results further strengthen the idea that the formation of SEF develops semiautonomously against embryonic development by using the nondestructive acoustic resonance technique as an indirect method to monitor yolk sac membrane formation.

Monitoring of eggshell breakage and eggshell strength in different production chains of consumption eggs.

We first tried to monitor the critical points for eggshell breakage in different logistic chains. Second, we examined whether there was a difference in eggshell strength among eggs produced in different housing systems. Finally, we developed a model to investigate the relation between eggshell strength and the likelihood of an egg cracking during handling and grading. Four logistic chains with different housing systems (battery cages, furnished cages, aviary, and free-range), all housing Bovans Goldline chickens in their mid-lay (45 wk), were compared. In every chain, a randomized set of 1,500 eggs was sampled, and the strength was defined. At every critical point in every logistic chain, the eggs were reexamined for breakage. The classic and furnished cage systems showed the highest percentage of breakage directly at point of lay (6.73 and 10.72%), whereas the other systems showed lower breakage (1.94% in the aviary and 1.99% in the free-range system). Further, in the logistic chain, grading and packing of the eggs generated the second highest percentage of breakage (from 1.50 to 2.65%). Breakage due to transportation ranged from 0.16 to 2.65%. There was a significant difference among the eggshell strength (shell stiffness and damping ratio) of eggs from chickens in different housing systems, showing eggs from chickens in the aviary system to be stronger than cage eggs (classic and furnished) and free-range eggs to be weaker than the other eggs. A significant correlation was found between eggshell strength and the likelihood of breakage in the production chains. In conclusion, it was first shown that, besides the laying, packing of the eggs is a critical point in the logistic chain of consumption eggs; second, the strength of the eggs in the different housing systems differed, and, finally, the eggshell stiffness and damping ratio of consumption eggs are an acceptable measure for rapid eggshell quality assessment and could provide a good predictive value for eggshell breakage in all types of table egg production chains.

The influence of line and laying period on the relationship between different eggshell and membrane strength parameters.

We investigated the correlations between different eggshell and membrane strength parameters and their changes over time. Eggshell and membrane characteristics were measured for 2 different lines of laying hens, Hisex Brown and Bovans Brown, from wk 33 up to wk 78. Several parameters were investigated: 2 parameters concerning total eggshell strength (static and dynamic stiffness), 1 structural parameter (i.e., eggshell thickness), 2 parameters describing the material characteristics of the shell [dynamic Young's modulus (EM) and nitrogen content], and 3 parameters to measure the membrane characteristics (attachment force breaking strength and nitrogen content). This study shows that the correlations among parameters change during the laying period and among lines. The EM of the eggshell increased during the laying period for the Hisex line. No difference was observed in case of the Bovans line. In general, a negative correlation was obtained between eggshell thickness and the EM. The correlation between static and dynamic stiffness increased during lay. Finally, the attachment force and breaking strength of the membranes declined during the laying period.

Use of the Foodtexture Puff Device to monitor milk coagulation.

The further automation of cheese-making on an industrial level requires the development of sensor devices to monitor the gelation process and especially the firming phase. In this paper, the Foodtexture Puff Device (FPD) is tested for its ability to monitor the gelation process by comparing it with classical rheometry (G' and G'') in a series of coagulations at different initial milk pH (6.01 to 6.61). The FPD measures the deformation of the surface of the milk during coagulation after applying an air puff directed on this surface. The maximal and minimal deformation values and the deformation range were calculated. A nonlinear model of the registered characteristics with the time point from adding rennet until the end of the gelation process was fitted on the FPD data and also on the classic rheology parameters. It was concluded that the FPD monitored the coagulation process in the same way as the rheology. Moreover, the start point of the coagulation process as well as the strength of the coagulum could be estimated nondestructively. Therefore, the presented technology together with the nonlinear model may be a basis for the development of an industrial monitoring device.

Dirt detection on brown eggs by means of color computer vision.

In the last 20 yr, different methods for detecting defects in eggs were developed. Until now, no satisfying technique existed to sort and quantify dirt on eggshells. The work presented here focuses on the design of an off-line computer vision system to differentiate and quantify the presence of different dirt stains on brown eggs: dark (feces), white (uric acid), blood, and yolk stains. A system that provides uniform light exposure around the egg was designed. In this uniform light, pictures of dirty and clean eggs were taken, stored, and analyzed. The classification was based on a few standard logical operators, allowing for a quick implementation in an online set-up. In an experiment, 100 clean and 100 dirty eggs were used to validate the classification algorithm. The designed vision system showed an accuracy of 99% for the detection of dirt stains. Two percent of the clean eggs had a light-colored eggshell and were subsequently mistaken for showing large white stains. The accuracy of differentiation of the different kinds of dirt stains was 91%. Of the eggs with dark stains, 10.81% were mistaken for having bloodstains, and 33.33% of eggs with bloodstains were mistaken for having dark stains. The developed system is possibly a first step toward an on line dirt evaluation technique for brown eggs.

Comparison of three lines of broiler breeders differing in ascites susceptibility or growth rate. 1. Relationship between acoustic resonance data and embryonic or hatching parameters.

Ascites is a prevalent cardiovascular disease among modern broilers with negative impacts on production and animal welfare. The peak of mortality due to ascites occurs at the end of the growing period, but the etiology of this problem may start during embryonic development. A few recent reports have demonstrated that the signs of ascites susceptibility are manifested during the late stages of incubation. In the current study, we used a nondestructive method based on egg acoustic resonance parameters [resonant frequency (RF) and damping] to establish a relationship between embryo physiological events during early development in broiler eggs and susceptibility to ascites. The hatching eggs of 3 broiler lines differing in ascites susceptibility were used for this study: ascites-resistant dam line (DAR), ascites-sensitive dam line (DAS), and ascites-sensitive sire line (SASL). These lines were selected on the basis of fast growth, high breast meat yield, and ascites induction at low temperatures such that the order of ascites susceptibility in terms of mortality was SASL >> DAS > DAR. Eggs were incubated under standard conditions in forced-draft incubators. We measured egg weights at setting, albumen pH, Haugh units (HU) at setting, and embryo weights at d 11 and 18, at internal pipping (IP), and at hatch. The durations of IP, external pipping (EP), and hatching were also determined. At 2 hourly periods during incubation, egg RF and damping were also measured. There were differences in egg weights between DAR and SASL vs. DAS, but albumen HU, albumen pH, and the ratio of yolk weight to egg weight were similar. There were differences in RF, damping, embryonic growth rates, and hatching events. Changes in resonant frequency and damping, which certainly suggest eggshell differences among lines, were not totally related to variations in physiological events during early and late embryonic development. A comparison between DAR and DAS, between DAS and SASL, or DAR and SASL indicates that sensitivity to ascites and selection for rapid growth rate in ascites-sensitive lines have different effects on embryonic parameters. We concluded that the sensitivity of broiler breeders to ascites does not influence egg internal quality, but the occurrence of ascites sensitivity in broilers could not be reliably predicted by early in ovo acoustic resonance parameters and hatching events.

An automatic monitoring of the hatching process based on the noise of the hatching chicks.

In this manuscript, a new tool is presented for automatic monitoring of the hatching process of eggs without opening the incubator doors. The amount of energy in the noise produced by the hatchlings was registered by means of a microphone and a personal computer for signal treatment. Evidence is shown that it is possible to detect exactly when the first chicks are hatched, the mean hatching time, and the finish of hatch. The information generated by this tool can be used by the hatchery manager to make the decision to end the incubation at the right moment, resulting in a higher number of first quality chicks without the risk of a reduced hatchability due to too early termination of the incubation process. The presented research also shows evidence that there is already a circadian rhythm in the newborn hatchling even when no external stimulus is present.

Changing albumen-membrane adhesive forces during early embryonic development.

Using acoustic resonance analysis, it is possible to detect embryonic development. In fertile eggs, the resonant frequency suddenly decreases after about 100 h of incubation. Previous research has shown that this decrease coincides with changing mechanical properties of the albumen near the shell, caused by the formation of subembryonic fluid (SEF). In the present experiment, the adhesive forces between the shell, the membranes, and the albumen were measured before and after the decrease in the resonant frequency. The adhesive forces between shell and outer membrane and between the 2 membranes remained constant, whereas the adhesive force between the inner membrane and the albumen, indirectly measured by a Kjeldahl analysis, increased significantly. Whether the decrease in resonant frequency is caused by the increase of adhesive force between albumen and inner membrane or by the changed properties of the membranes (both of which are altered by dehydration of the albumen) is still open for discussion.

Effects of egg storage time on spread of hatch, chick quality, and chick juvenile growth.

A total of 1,800 incubating eggs produced by a commercial flock of Cobb broiler breeders was used to determine the effects of storage duration (3 or 18 d) on spread of hatch and chick quality. Chick relative growth (RG) at the end of 7 d of rearing was also determined as a measure of the chick performance. Chick quality was defined to encompass several qualitative characteristics and scored according to their importance. Eggs stored for 3 d hatched earlier than those stored for 18 d (P < 0.05). Hatching was normally distributed in both categories of eggs, and the spread of hatch was not affected by storage time (P = 0.69). Storage duration of 18 d reduced the percentage of day-old chick with high quality as well as average chick quality score (P < 0.05). RG varied with length of egg storage, quality of day-old chick, and the incubation duration (P < 0.05). Eighteen-day storage of eggs not only resulted in longer incubation duration and lower quality score but also depressed RG. Chick quality as defined in this study was correlated to RG and storage time. It was concluded that day-old chick quality may be a relatively good indicator of broiler performance. The results suggest however that in order to improve performance prediction power of chick quality, it would be better to define it as a combination of several qualitative aspects of the day-old chick and the juvenile growth to 7 d.

Effects of storage time on incubating egg gas pressure, thyroid hormones, and corticosterone levels in embryos and on their hatching parameters.

Incubating eggs (1,800 total) produced by a commercial flock of Cobb broiler breeders were used to determine the effects of storage duration (3 and 18 d) on gas partial pressure, thyroid hormones, and hatching parameters. Partial pressure of oxygen (pO2) and carbon dioxide (pCO2) were measured on d 18 and at internal pipping (IP) during incubation. Blood samples were collected for determination of triiodothyronine (T3), thyroxine (T4), and corticosterone concentrations in the embryos at IP and in newly hatched chicks. From 464 to 510 h of incubation, eggs were checked individually every 2 h to determine the timing and duration of IP, external pipping (EP), and total hatching time. At 18 d of incubation and at IP, pCO2 was greater in air cell of eggs stored for 3 d compared to those stored for 18 d (P < 0.05), but pO2 was greater in eggs stored for 18 d. At IP, T3 and corticosterone levels were higher in plasma of the embryos of eggs stored for 3 d compared to those stored for 18 d, but it was the reverse in newly hatched chicks (P < 0.05). Embryos from eggs stored for 18 d required more time to complete IP compared to embryos of eggs stored for only 3 d (P < 0.05), whereas the duration of EP was not affected by storage. The overall longer incubation was, however, not only due to prolonged IP but also to later occurrence of IP. It was concluded that prolonged IP as a result of long storage may be related to the late increase in corticosterone level, which may be a necessary stimulus for higher T3/T4 ratio, late increase in pCO2 level, and decrease in pO2. The effect of long storage was a delay in hatching and a continuous increase in T3 due to higher corticosterone levels between IP and hatching, which may be an indication of the more stressful event of hatching of embryos from eggs stored longer. Differences in pCO2, pO2, T3, T4, and corticosterone levels in the incubating eggs may be manifestations of these changes culminating in altered hatching parameters and consequently differences in chick quality and growth potentials.

Detection of early embryonic development in chicken eggs using visible light transmission.

1. In two separate experiments, the possibility of detecting embryonic development in chicken eggs was assessed using the same spectrophotometric method used to detect blood in Table eggs, using a combination of two wavelengths (577 and 610 nm) of the transmission spectrum. 2. In the first experiment, during the first 10 d of incubation, transmission spectra of 30 Hisex White eggs and 30 Hybro eggs were measured daily. 3. In the second experiment, 292 Hisex White eggs were incubated. Seven groups were randomly assigned. Six received an injection of sodium azide (NaN3) at different times during incubation in order to stop embryonic development, and during the first 12 d of incubation the transmission spectrum was measured daily. The acoustic resonance analysis method was also used on a group of uninjected eggs. 4. In the first experiment, it was possible to detect embryonic development from 120 h of incubation onwards in fertile eggs. In the second experiment changes in light transmission due to embryonic development were detected from 108 h of incubation. Detection of embryonic development using the acoustic resonance analysis method in the second experiment was possible only from 120 h of incubation. 5. It was concluded that the detection of embryonic development using visible light transmission is not directly linked with the formation of blood, but with the formation of sub-embryonic fluid, which takes place from 72 h of incubation onwards. This fluid makes the yolk sac translucent so that absorption of light at 577 nm can be detected.

Effect of induced molting on albumen quality, hatchability, and chick body weight from broiler breeders.

Commercial Cobb broiler breeders were subjected to molting from 55 to 62 wk of age. Incubating eggs were collected before molting and after molting and were stored for 18, 13, 8, or 3 d. Sample eggs were broken to measure albumen Haugh units (HU) and pH. Two hundred twenty-five eggs per treatment, stored for 18, 13, 8, or 3 d, were incubated for 21 d; the hatched chicks were weighed at the end of incubation and again after Day 7 of rearing. As the storage time increased, albumen HU decreased (P < 0.001). At all storage times, HU after molting were higher than those before molting (P < 0.001). Albumen pH increased with storage time (P < 0.001). A molting x storage interaction on pH was observed after 8 d of storage (P = 0.03). Hatchability of eggs increased after hens were molted, if the eggs were stored for a long time (P < 0.001). Body weights of 1-d-old chicks from the eggs of hens before molt were heavier than those from eggs after molting (P < 0.001). Conversely, at 7 d, the chicks from the eggs after molting were significantly heavier than those from eggs before molting (P < 0.001). We concluded that molting was a procedure to improve hatchability and chick juvenile growth. If eggs need to be stored, we recommended that fresh eggs with high HU value be stored rather than those with low HU values.