Flip Bamelis

THE DAY-OLD CHICK: A CRUCIAL HINGE BETWEEN BREEDERS AND BROILERS

The quality of the day-old broiler chick is foremost in the minds of many poultry managers. From fertilised ovum to the placement at the broiler farm, some factors such as the characteristics of the incubating eggs, the egg holding conditions, the incubation conditions and the conditions that exist between hatching and placement at the farm and their interactions may affect chick quality. It may be questioned if maximal hatchability is the best indicator for chick quality and/or post-hatching viability, even if optimal hatchability is considered a prerequisite for successful incubation. The environmental conditions during incubation (e.g. the temperature, humidity and ventilation rate (carbon dioxide concentration)) are not set independently from each other, although each may have its own optimum for hatchability and chick quality. These optima for each incubation factor may alter differentially according to the characteristics of the incubating egg. It is concluded that more independent control as well as more control of the variability of the classical physical conditions in the incubator are required in order to improve hatchability and chick quality.

Non-destructive measurements of the egg quality

Due to the increasing throughput of modern egg grading machines, which grade up to 120 000 eggs per hour, the visual inspection of eggs by humans (“candling”), becomes a critical bottleneck in the egg sorting chain. In order to assure a high and consistent egg quality, researchers investigated the use of modern sensor technologies to replace the candling operation. During the last decades, several types of sensors were developed, and it is believed that these sensors will replace human candling in the near future. A first class of sensors is based on mechanical techniques and allows investigation of the physical shell quality, such as the presence of cracks and shell strength. A second class is based upon spectroscopic principles and allows the operator to “see” through the egg shell in order to determine the internal quality of the eggs, such as albumen pH and viscosity and the presence of inclusions such as blood and meat spots. A third class of sensors aims at mimicking the human eye by means of a camera and a software platform (“computer vision”). Besides these types of sensors, some others based on ultrasonic, magnetic resonance and electronic nose principles are investigated and discussed. This paper gives an overview of these modern sensor technologies for egg grading.

Eggshell Penetration of Various Types of Hens' Eggs by Salmonella enterica Serovar Enteritidis

Egg weight, shell thickness, number of pores, cuticle deposition, eggshell strength (dynamic stiffness and damping ratio), and the ability of Salmonella enterica serovar Enteritidis (SE) to penetrate the eggshell were determined. Penetration was assessed by filling the eggs with a selective medium that allowed viewing of Salmonella growth on the inside of the shell and membrane complex. After inoculation of each shell with on average 2.71 log CFU, the eggs were stored for up to 14 days at 20 degrees C and 60% relative humidity. Commercially available eggs were used. At 14 days of storage, only 6.0% of the eggs from free-range hens and 16.0% of the generic (i.e., eggs from hens in conventional battery cages that were given standard feed) white eggs were penetrated. The generic brown, organic, and omega-3-enriched eggs were penetrated at a frequency of 30 to 34%. In a second experiment it was shown that the layer strains of the hen (ISA-Brown Warren versus Bovans Goldline), which were kept in furnished cages, did not affect eggshell penetration by SE. For Bovans Goldline hens, the housing system (furnished cage versus aviary) did not affect penetration, while a trend was visible toward a higher fraction of penetrated eggshells when hens were fed corncob mix rather than standard feed. Eggshell penetration was observed more frequently in the absence of cuticle spots and for eggs having lower dynamic stiffness values. Shell contamination at the end of storage was highly correlated with SE penetration.

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 (NaN 3 ) 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.

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.

Vibration Analysis on Incubating Eggs and Its Relation to Embryonic Development

Coucke (1998) was the first to use acoustic resonance analysis to monitor embryo development in chicken eggs. He remarked that at around 100 hours of incubation, the course of the resonant frequency and damping changed abruptly in the case of fertile eggs. He also showed that these changes were related to a physiologic event during early embryonic development. The objective of our study is to monitor the course of the vibration parameters during the early incubation of chicken eggs and to relate these changes to egg and embryo characteristics. A total of 72 Hybro eggs were incubated vertically in a small incubator at standard conditions. Several egg parameters were measured before incubation. During the early stages of incubation the vibration behavior of these eggs was monitored. The time at which the damping of the vibration suddenly changed, the diameter of the eggs and their interaction were found to be significant explanatory variables in order to predict hatching time. A correlation coefficient r of 0.72 was obtained.

Assessment of embryonic growth in chicken eggs by means of visible transmission spectroscopy.

During this work, it was investigated whether spectral measurements can be used to monitor embryonic growth. An experiment was conducted in which both the transmission spectra and embryonic weight were determined on 240 eggs (Cobb, 37 weeks) between Day 5 and Day 10 of incubation. The spectral data were linked to embryonic weight by means of a partial least squares analysis. Different preprocessing procedures were compared during this work, that is, smoothing, multiplicative scatter correction (MSC), and first‐ and second‐order derivative. Compared to the remainder of the preprocessing procedures, MSC leads to a considerable improvement of the prediction capability of the embryonic weight. The ratio of performance to deviation obtained for the MSC spectra equaled 4.5 indicating that a very accurate prediction of embryonic weight is feasible based on the VIS/NIR transmission measurements. Important regions for the prediction are situated around 685–740 nm. It is suggested that the spectral changes in these spectral regions result from the displacement of carotenoids from the yolk into the blood circuitry.

Eggs and Egg Products

To a great extent eggs and egg products used in the food industry are bought in either the frozen or dried state. The objective of either drying or freezing is to retain the native characteristics of the raw egg to the greatest possible extent. Egg yolks and whole eggs are spray-dried commercially, while egg whites may be either spray-dried (powder) or pandried (flaked).

The potential of spatially resolved spectroscopy for monitoring angiogenesis in the chorioallantoic membrane.

Over the last decade, the poultry sector has sought to develop ways to monitor chicken embryonic development as to optimize the incubation conditions. One of the parameters of development which may change under different incubation conditions is the angiogenesis in the chorioallantoic membrane (CAM). To be able to quantify these changes in the angiogenesis and detect long‐term effects on health, a non‐destructive technique is necessary. In this article, the first steps toward such a non‐destructive technique are successfully taken. A spatially resolved spectroscopy set‐up is built and tested for its potential to measure changes in angiogenesis with incubation time, and differences between a normal and hypercapnic incubation. In this first study, reflectance measurements are performed directly on the CAM as the eggshell considerably complicates the analysis. This issue should be addressed in future research to come to a really non‐destructive technique. An experiment was conducted in which one group was incubated under normal conditions, and another under early prenatal hypercapnic conditions (i.e., increased CO2 concentrations). The angiogenesis in the CAM was measured at embryonic day (ED) 10, 13, and 16. The measurements showed a clear blood spectrum with an increasing amount of blood in time, and significant differences in the reflectance as function of the source‐detector distances. However, no significant differences between the hypercapnia and the control group could be detected.

Multi-objective optimization of a flash lamp drive

To adjust the light spectrum of a flash lamp, the current flowing through the flash lamp has to be controlled. An optimal design of a switched resistor bank circuit following a predefined current profile is presented. The optimal values of the switched resistors are calculated using multi-objective optimization with genetic algorithms.