B. Kamers

Acid-base balance in chicken embryos (Gallus domesticus) incubated under high CO2 concentrations during the first 10 days of incubation.

Recent studies show the importance of differential CO2 levels during the first half of incubation of chicken eggs on embryonic and postnatal growth. However, it is not known how external higher CO2 levels affect embryonic acid-base balance. In this study, the effect of an early rise in CO2, between 25th and 96th hour of incubation to 1.5% and maintained at that level until 240 h of incubation, was investigated on air cell gases, blood gas parameters from ED10 onwards and on embryonic growth and hatching parameters. Higher external CO2 concentrations resulted in a faster acidification of albumen resulting in a faster decrease of albumen pH with development, illustrating the capacity of albumen to cope with higher environmental CO2. Moreover, PCO2 in blood was higher in CO2 incubated embryos at embryonic day 10 and 11 but without a change in blood pH. The additional increase in plasma HCO3- concentration at day 10 and 11 was responsible for buffering the higher PCO2 in CO2 incubated embryos in order to stabilize pH. However, effects of hypercapnia on blood acid-base parameters extinguished 2 days after termination of high CO2 incubation. Embryonic growth was modestly accelerated which was reflected in higher embryonic weights at day 6 and 10 and a significant earlier hatching; hatchling weights were not different between treatment groups.

The Effect of Nonventilation During Early Incubation on the Embryonic Development of Chicks of Two Commercial Broiler Strains Differing in Ascites Susceptibility

Despite thorough selection during the last decade, the incidence of ascites is still high in modern broiler strains. Although ascites occurs mostly at the end of the rearing period, there are indications that the etiology of this problem may have started during embryonic development. Recent studies have shown that the post-hatch performance of the broiler chick might be influenced by changing the environmental conditions in the incubator during embryonic development. This study investigated the effect of increasing incubator CO(2) concentration up to 0.7%, by nonventilation during the first 10 d of incubation, on the embryonic development of 2 commercial broiler strains (Cobb and SAS) differing in their susceptibility for ascites syndrome. The Cobb strain is suspected to be less susceptible than the SAS strain. Overall, the chick embryos of the Cobb strain had a faster development than those of the SAS strain as expressed by their higher BW from embryonic day (ED)10 until ED18. Nonventilation stimulated embryonic development resulting in higher embryonic BW, early hatch, and narrower spread of hatch in both strains. In the SAS strain, nonventilation improved hatchability by more than 10%. Gas composition of the air cell in the egg of the nonventilation groups (both Cobb and SAS) had higher partial pressure of CO(2) and lower partial pressure of O(2) from ED11 until ED14 compared with the ventilation groups. During the entire incubation period, partial pressure of CO(2) was higher in eggs of the Cobb strain compared with the SAS strain. Plasma triiodothyronine, thyroxine, and corticosterone levels were different at the end of the incubation period and during hatching due to nonventilation at the beginning of incubation. It is concluded that nonventilation during the first 10 d of incubation had a stimulatory effect on embryonic development of the 2 broiler strains with no effect of heart weights but with effects on hormone levels, air cell pressures, and hatching parameters.

The transmission color value: A novel egg quality measure for recording shell color used for monitoring the stress and health status of a brown layer flock

Stress and diseases have the potential to influence the deposition of eggshell pigmentation during egg formation. Therefore, defining the shell color of eggs on a daily basis could be a representative method for monitoring stress or health status of a flock and maintaining good performance. A novel way of measuring eggshell color based on visible-near infrared transmission spectroscopy transmission spectra was defined: the transmission color value (TCV). The TCV was calculated as the ratio between the transmission at 643 nm (maximum absorbance of the pigmentation molecule protoporphyrin IX) and the transmission at 610 nm (a reference wavelength). Experiments were carried out to investigate the relevance of TCV for monitoring flock stress and health or even anticipating any factors unfavorable to performance. In 2 small experimental flocks, deliberate heat stress challenges were applied. A medium-scale experimental flock in an aviary was monitored on a daily basis during the whole productive period. From the deliberate heat stress challenges, it was seen that stress had a significant effect on eggshell pigmentation. This observation was confirmed in a daily monitored flock, in which, for example, an infectious bronchitis infection occurred. These stress situations were quickly reflected by an increased TCV value: more transmission due to less pigmentation and hence less absorbance at the pigmentation wavelength. Furthermore, for the observed problems in the daily monitoring, the TCV value signaled the problem earlier (4 d) than the average egg weight or even signaled when the other parameters did not signal anything. Measuring the TCV of all eggs produced on a daily basis provides relevant information on the stress or health status of a flock of brown layers. This could be used as an early detection of stress situations or emerging diseases, even before important quality and health damage can occur.

Comparison of Cobb and Ross strains in embryo physiology and chick juvenile growth.

Broiler performance is known to be related to embryonic developmental parameters. However, strain or genotype differences with regard to embryo physiological parameters and juvenile growth have received little attention. A total of 1,200 hatching eggs produced by Cobb and Ross broiler breeders of the same age were studied. At setting for incubation and between 66 and 130 h of incubation, egg resonant frequency (RF) was measured as an indicator of embryonic development. Also, eggs were weighed before setting and at d 18. From d 10 to 18 of incubation, remaining albumen was weighed. During the last days of incubation, hatching events such as internal pipping (IP), external pipping, and hatch were monitored every 2 h. Hatched chicks were recorded and weighed. At IP stage, gas partial pressures in the egg air chamber were measured. Hatched chicks were reared for 7 d and weighed. Results indicate that RF of Ross eggs were lower than those of Cobb eggs (P < 0.01) and starting time point of RF decrease occurred earlier in Cobb eggs than in Ross eggs. Relative egg weight loss up to 18 d of incubation was lower in Cobb than in Ross (P < 0.05). At IP, partial pressure of CO(2) was higher in Cobb than in Ross (P < 0.05) with shorter incubation duration in Cobb. Between 6 and 60 h posthatch, heat production was higher in Cobb than in Ross (P < 0.05). At 7 d posthatch, Cobb chicks were heavier than Ross chicks (P < 0.05). It is concluded that Cobb and Ross embryos-chicks have different growth trajectories leading in different patterns of growth resulting from differences in physiological parameters.

Changes in acid-base balance and related physiological responses as a result of external hypercapnia during the second half of incubation in the chicken embryo.

This study investigated the effect of high CO2 (4%) from embryonic day (ED)10 until ED16 on the acid-base balance and related parameters in the chicken embryo. From ED10 to ED16, blood was taken from a vein from the chorioallantois membrane and was analyzed for pH, partial pressure of CO2, partial pressure of O2 (pO2), [HCO3(-)], [K+], and [Ca2+]. Allantoic fluid was taken for measurement of pH, NH3-N, phosphate, and calcium concentration. The right tibia was ashed, and calcium was measured with atomic absorption spectroscopy. Embryos exposed to high CO2 showed a consistent higher blood pH than control embryos. Notwithstanding this alkalosis, bicarbonate concentration was significantly higher in the CO2 group from ED12 until ED16. Potassium concentration in the blood was significantly higher in the CO2 group from ED11 until ED16. The pH of the allantois was significantly higher on ED14 and ED15. Ammonia N concentration was significantly higher in the CO2-incubated embryos on ED12 and ED13, whereas phosphate did not differ between groups. Calcium per tibia dry weight did not differ between incubation conditions. We can conclude that embryos adapt to high CO2 during the second half of incubation by increasing blood HCO3(-). It appears that this increase in HCO3(-)is mainly the result of the stimulated intracellular exchange of H+ with K+, although temporary reabsorption of HCO3(-)by the kidney cannot be excluded.

Modeling torque-angle hysteresis in a pneumatic muscle manipulator

Hysteresis is inherently present in Pneumatic Artificial Muscle (PAM) Actuators. Our new observation shows that the hysteresis in a PAM is characterized by quasirate independency and history dependency, and is completely described by the Maxwell-slip (MS) model. In this paper, we explain how to model the existing hysteresis in an antagonistic PAM configuration, using the models derived for the individual PAMs. Experimental results show that the pneumatic manipulator hysteresis has the same behaviors as those found in a single PAM. The proposed model is used to predict the output torque of the manipulator joint not only for any arbitrary angular displacements but also for any arbitrary pressure difference.

Regulatory capacities of a broiler and layer strain exposed to high CO2 levels during the second half of incubation

It has been shown that during embryonic chicken (Gallus gallus) development, the metabolism of broiler embryos differs from that of layers in terms of embryonic growth, pCO2/pO2 blood levels, heat production, and heart rate. Therefore, these strains might adapt differently on extreme environmental factors such as exposure to high CO2. The aim of this study was to compare broiler and layer embryos in their adaptation to 4% CO2 from embryonic days (ED) 12 to 18. Due to hypercapnia, blood pCO2 increased in both strains. Blood bicarbonate concentration was ~10 mmol/L higher in embryos exposed to high CO2 of both strains, while the bicarbonates of broilers had ~5 mmol/L higher values than layer embryos. In addition, the pH increased when embryos of both strains were exposed to CO2. Moreover, under CO2 conditions, the blood potassium concentration increased in both strains significantly, reaching a plateau at ED14. At ED12, the layer strain had a higher increase in CAII protein in red blood cells due to incubation under high CO2 compared to the broiler strain, whereas at ED14, the broiler strain had the highest increase. In conclusion, the most striking observation was the similar mechanism of broiler and layer embryos to cope with high CO2 levels.

Interaction between ascites susceptibility and CO2 during the second half of incubation of two broiler lines: the effect on post-hatch development and ascites mortality

1. The aim of this study was to investigate if genetic predisposition to ascites interacts with changed incubation conditions, and how this might affect the post-hatch performance and ascites susceptibility. 2. An ascites sensitive (A) and resistant (E) broiler line were incubated under standard or high CO2 conditions (up to 4%) from embryonic d 10 onwards. After hatch, chicks were exposed to cold from the 15th day of the rearing period to increase the incidence of ascites. 3. The A line had a higher post-hatch body weight from week three, higher blood pCO2 from d 21, higher haematocrit at d 35 and d 42, and higher plasma corticosterone concentration from d 21 onwards, compared with the E line, regardless of incubation conditions, supporting the given selection criteria. Ascites mortality did not, however, differ between lines. 4. Incubation under high CO2 conditions during the second half of incubation increased the ascites mortality, decreased body weight from week 4 onwards, affected venous blood pCO2, decreased blood pO2 from d 31, increased haematocrit at d 35 and d 42, and lowered the thyroxine and triiodothyronine concentrations at most sampling days. These effects were observed in both lines. The results suggested a metabolic programming of CO2 incubated chickens which affected ascites susceptibility.

Interaction between ascites susceptibility and CO during the second half of incubation of two broiler lines. Effect on embryonic development and hatching process.

1. Because CO2 during the second half of incubation is known to influence air cell and blood gases, and embryo development, it is postulated that post-hatch development and ascites sensitivity could also be influenced. 2. An ascites susceptible (A) and an ascites resistant (E) broiler line were incubated under standard incubation or high CO2 conditions (up to 4%) from embryonic day (ED) 10 onwards. The embryonic development and the hatching process of these two lines were compared when incubated under standard or high CO2 conditions from over the second half of incubation. 3. The A line, selected for high post-hatch growth rate, exhibited a higher relative embryo weight from ED10 until ED16, which was supported by a higher air cell pCO2, lower air cell pO2, higher corticosterone and thyroid hormones and earlier hatching time. 4. Incubation under high CO2 increased air cell pCO2, retarded yolk consumption, and decreased glycogen concentration in the liver at hatch. Hatchability decreased in both lines when incubated under high CO2, due to an increased late mortality of embryos that died before IP. 5. These results suggest that the development and metabolism of CO2-incubated embryos differ from control incubated embryos.

A model for promoting poultry industry development in Togo: feeding improvement, capacity building and extension

Although being the main bottlenecks for commercial poultry development in Togo, feeding and management practices retain little attention. Indeed, there is no proficient feed miller unit which can provide high quality feed according to the needs of the farmers. This is due to a lack of information on nutrition and relevant management tools or people trained as poultry farm managers. With the aim to alleviate poverty and hunger in Togo, an inter-university project [Catholic University of Leuven (KUL) and University of Lome (UL)] as a model for poultry development was being run from June 2006 to May 2012. Specific objectives of the project are 1) to provide insights and disseminate guidelines and information on adapted methods to improve poultry production and 2) to focus on development of new technologies in poultry production and implementation of research on better poultry nutrition, feeding and management practices.