Plateau Stage In Oxygen Consumption Research Articles

Dam Line and Sire Line Effects on Turkey Embryo Survival and Thyroid Hormone Concentrations at the Plateau Stage in Oxygen Consumption

Inheritance of embryo thyroid function was measured in lines of turkeys. Two lines that had been selected for either increased egg production (E) or increased 16-wk BW (F) and their respective randombred controls (i.e., RBC1 and RBC2) were examined. Reciprocal crosses of dams and sires from each selected line and its randombred control were made to estimate sire line and dam line effects. Orthogonal contrasts were used to determine if the differences found were due to the presence of additive, nonadditive, or maternal, sex-linked, or both, gene effects. With the data involved, sex-linkage and maternal effects could not be separated. Embryo survival was measured for all lines and their reciprocal crosses. Crossing the RBC1 sire and E dam also resulted in better embryo survival and lower death losses at pipping than for the other cross- or purelines. Reciprocal crosses of the F and RBC2 lines showed better total embryo survival, and they survived pipping better than the F or RBC2 purelines. Thyroxine (T4) and triiodothyronine (T3) concentrations differed between the reciprocal crosses at external pipping, but the effects were inconsistent for the 2 data sets. Reciprocal tests indicated that maternal, sex-linked, or both, effects were present for T3 concentrations at internal pipping in the E and RBC1 lines and at external pipping for the F and RBC2 lines. Reciprocal effects were significant for T4 at internal pipping for both data sets. The RBC1 sire embryos had significantly higher T3:T4 ratios than the E line sire embryos at internal and external pipping, and the pureline RBC1 embryos had consistently higher ratios than the pureline E embryos. The differences for the T3:T4 ratios between these 2 lines at internal pipping, external pipping, and hatch appeared to be consistently additive in nature, although significant nonadditive or heterotic effects were present for the ratio at external pipping. Similar effects on the T3:T4 ratio were observed for the F and RBC2 lines at external pipping.

Effect of Incubator Temperature and Oxygen Concentration at the Plateau Stage in Oxygen Consumption on Turkey Embryo Muscle Growth and Development

Effect of Incubator Temperature and Oxygen Concentration at the Plateau Stage in Oxygen Consumption on Turkey Embryo Muscle Growth and Development

Shell Thickness of Turkey Eggs Affects Cardiac Physiology and Embryo Survival

4 Abstract: Supplementing 500 ppm of a chelated calcium proteinate (CCP) to a commercial breeder diet resulted in thicker shells and improved embryo livability. The CCP diet was fed to one half of a flock of breeders on a commercial farm that was suffering shell problems, and a standard commercial diet was fed to the remaining half. Egg production, eggshell thickness, fertility and hatchability of eggs were all monitored over an 18 wk laying period. Feeding CCP increased shell thickness and reduced numbers of cull eggs after 8 wk of lay compared to the controls. When differences in eggshell thickness were seen after 10 weeks of egg production, embryo survival and cardiac physiology were examined in three trials comparing the thicker shells to thin. Thick shells (0.44 versus 0.39 mm) improved embryo survival 2% by decreasing numbers of embryos dying late in development compared to controls and affected cardiac physiology. Thus, thick shells may improve embryo viability by affecting cardiac health during the plateau stage in oxygen consumption.

Incubator Environment Interacts with Genetic Line of Broiler at the Plateau Stage to Affect Embryo Plasma Thyroxine and Triiodothyronine Concentrations

We hypothesize that temperature and oxygen in conjunction with genetic lines of broilers regulate embryo thyroid function. Thyroid response of broiler embryos of the two lines was measured at differen t incubator temperature and oxygen concentrations at the plateau stage in oxygen consumption (days 17 to 20 of embryo development). Each of the lines showed different eggshell conductance (G) values. Eggs of the same weight from the lines of broilers were incubated identically until the 17 day of development. On th

Incubator Temperature and Oxygen Concentration at the Plateau Stage in Oxygen Consumption Affects Intestinal Maturation of Broiler Chicks

Incubator temperature and oxygen concentrations were tested as factors determining the intestinal maturation of two lines of broiler chickens. One line was a Low G line selected because its eggs display low eggshell conductance. The second line was a High G line that grew at a reduced rate and its eggs show high eggshell conductance values. All eggs were incubated normally until the 18 day of development or the th beginning of the plateau stage in oxygen consumption. At that time the eggs were divided randomly and placed into experimental cabinets operating at 36, 37 38 or 39oC in experiment 1 or with 17, 19, 21 or 23% oxygen in experiment 2. In experiment 3, the best and worst conditions observed in experiments 1 and 2 were combined in a factorial arrangement. Body weight and intestinal maturation were measured by assaying for maltase and alkaline phosphatase activities in intestinal tissues. Increasing temperatures suppressed intestinal maturation whereas increasing oxygen concentrations enhanced intestinal maturation. When examined together in a factorial arrangement, it was clear that the effects of temperature and oxygen on the embryos were independent because they did not interact. The effects of temperature and oxygen were greater on Low G broiler embryos than they were on High G type embryos. It is concluded that incubator temperatures greater than 37o C, and oxygen concentrations less than 21% are detrimental to intestinal maturation in broiler chicks.

Incubator Temperature and Oxygen Concentrations During the Plateau Stage in Oxygen Uptake Affect Turkey Embryo Plasma T4 and T3 Concentrations

Avian embryo thyroid responses to incubator temperature and oxygen concentrations during the plateau stage in oxygen consumption were measured. It was hypothesized that turkey embryo thyroid responds in a limited way at this critical time to environmental conditions to modulate basal metabolism. Turkey embryos were exposed to one of four incubator temperatures (36, 37, 38 or 39 C) beginning on the o 25 day of incubation at the onset of the plateau, a time when plasma thyroxine (T ) and triiodothyronine (T ) th 4 3 concentrations normally increase. Blood was collected and thyroid hormone concentrations were measured at pipping (27 day) and hatching (28 day). Elevated temperatures depressed T and T concentrations and th th 3 4 increased the T to T ratios. In a second experiment four oxygen concentrations (17, 19, 21 or 23% oxygen) 3 4 were provided to the embryos using identical procedures. The 21% treatment significantly reduced T and 3 T at pipping compared to all other treatments, but 23% oxygen increased plasma T and the T to T ratio 4 3 3 4 compared to all other treatments. The 17% oxygen treatment elevated T compared to all other treatments. 3 At hatching, 23% oxygen elevated T and T to T ratios compared to all other treatments. When temperature 3 3 4 and oxygen treatments were applied together in a factorial arrangement, temperature and oxygen affected T and T hormone concentrations independently but did not interact. Therefore, we conclude that 3 4 temperature and oxygen are independent stimuli of the avian embryonic thyroid gland during the plateau stage, and that incubator temperature and oxygen concentrations can modulate development of turke y embryos by changing plasma T and T concentrations. 3 4

Incubator Temperature and Oxygen Concentration at the Plateau Stage Affects Intestinal Maturation of Turkey Embryos

The plateau stage in oxygen consumption of turkey embryos occurs at 25 and 26 days of incubation when many embryos die. The plateau stage creates hypoxia, hypercapnia and presents a paradox for growth and embryo metabolism. Prior to the plateau, vital tissues accumulate glycogen to ensur e embryonic survival through anaerobic metabolism during the plateau. Intestinal maturation at the plateau demands great amounts of energy. Therefore, the objective of the study was to define the temperature and oxygen concentrations at the plateau that affect intestinal maturation. Three experiments were conducted to test incubator conditions during the plateau stage and their affect on intestinal maturation. In Experiment 1, turkey embryos at the plateau stage were exposed to 36, 37, 38 or 39 C. In Experiment 2, embryos at the o plateau stage were exposed to 17, 19, 21 or 23% oxygen concentrations, and in Experiment 3, the extreme levels of temperature and oxygen treatments were combined to test interaction effects on intestina l maturation. Elevating temperature depressed intestinal weight but not length. The elevated temperature also depressed intestinal maltase and alkaline phosphatase activities indicating inhibited function. Increasing oxygen had little effect on intestinal weight or length, but hypoxia increased maltase and decreased alkaline phosphatase activities in hatchlings. When examined in a factorial arrangement, temperature and oxygen displayed independent effects on growth and function and did not interact. Thus, incubator temperature greater than 37 C and oxygen concentrations less than 19% during the plateau stage delay intestinal o maturation.

Egg Storage Effects on Plasma Glucose and Supply and Demand Tissue Glycogen Concentrations of Broiler Embryos

The hypothesis was tested that enhanced embryonic carbohydrate metabolism may enable embryos to survive egg storage effects. As lines of broiler breeders age, some lines resist detrimental effects of egg storage on embryonic survival, whereas others do not. Fertile eggs were obtained from two lines differing in storage ability. Eggs from each line by age group were stored for 1 or 14 d prior to setting. Eggs were distributed randomly into a single machine and incubated under standard conditions. Beginning at 17 d of incubation, immediately prior to the plateau stage in oxygen consumption, embryos from each of the treatment groups were sampled for BW, organ growth, glycogen concentration, and plasma glucose concentrations. Sampling continued through hatching. Plasma glucose concentrations increased significantly, and hepatic glycogen concentrations declined as embryos approached hatching. The rate at which glycogen was accrued into muscle and heart tissue displayed a significant three-way interaction among line, age, and storage. Embryos from the line that resisted storage mortality maintained greater glycogen concentrations in muscle and heart tissues than those from the line and age with diminished survival rates. It was concluded that embryonic survival rates differ following egg storage because of the ability of the embryo to accrue and maintain adequate carbohydrate for growth and function of vital demand tissues.

Effect of supplemental oxygen on blood plasma organic acids within embryos from selected lines of turkeys

The hypothesis was tested that increased oxygen tensions during the plateau stage of oxygen consumption (25 and 26 d of incubation) would cause different metabolic responses from embryos selected for increased egg production or growth. Embryos were exposed to 171 or 152 mm Hg partial pressure of oxygen from 25 to 28 d of incubation, a time when the oxygen conductance properties of the eggshell are exceeded by the embryonic tissue demands for oxygen. Carbohydrate and lipid metabolism were observed by measuring plasma organic acids in embryos from selected lines and randombred controls. (E was selected for increased egg production; RBC1 is the randombred line from which it was selected. F was selected for increased BW; RBC2 is the randombred line from which it was selected.) During the plateau stage in oxygen consumption, RBC2 embryos responded to added oxygen by utilizing fat rather than carbohydrate, whereas F embryos responded by using less fat as well as less carbohydrate from the liver and kidney. The response of F embryos to added oxygen is the opposite that might be expected for aerobic metabolism. The reason that selection for growth has resulted in such a metabolism is unknown. The E embryos displayed depressed lactate and beta-hydroxybutyrate levels, but plasma urates were elevated compared with RBC1, suggesting that the selection for egg production has also resulted in a unique metabolism. The embryonic processes described in the current study suggest that selected embryos are unable to respond to elevated partial pressure of oxygen by adjusting energy metabolism, which may result in increased embryonic mortality during this stage.

Effects of an oxygen-enriched environment on the survival of turkey embryos between twenty-five and twenty-eight days of age

The hypothesis was tested that increased partial pressure of oxygen during the plateau (25 to 26 d of incubation for turkeys) and paranatal (27 to 28 d of incubation) stages of incubation may increase survival rates of turkeys from selected genetic lines. Partial pressure of oxygen inside the incubator cabinet was increased to 171 + 3 mm Hg of the barometric pressure during the plateau stage in oxygen consumption and compared to ambient oxygen (152 + 3 mm Hg). Turkey embryos from genetic lines selected for egg production (E) or growth (F) were compared to their respective randombred controls. These genetic lines have previously been shown to differ in egg weight, eggshell conductance, length of incubation period, embryonic gluconeogenesis, and survival rates during late incubation. Blood, liver, heart, and pipping muscle samples were obtained prior to pipping, at internal pipping and external pipping, and at hatching. The blood was analyzed for glucose concentration and the remaining tissues were assayed for glycogen concentrations. Survival rates were determined on approximately 2,200 eggs in each of three independent trials of the experiment. Interactions of oxygen treatment and genetic line were observed for embryonic survival, heart growth, and hepatic glycogen content. The data suggest that the response to increased oxygen tension in selected genetic lines has been diminished. It was concluded that embryos have been altered metabolically by genetic selection and the concomitant increase in mortality of selected lines during the plateau and paranatal stages is not simply the result of shell quality and hypoxia.

Eggshell Conductance and Other Functional Qualities of Ostrich Eggs

Eggshell conductance was measured and eggshell conductance constants were calculated for eggs from ostriches. In addition, egg water, yolk, albumen, shell, and total solids were measured in an effort to determine the maternal investment of ostrich eggs. The results of the study suggest that the optimal incubator humidity for ostrich eggs is less than 25% to allow a 15% loss of initial egg mass during the 45-d incubation period. This low humidity does not preclude increasing humidity during the actual hatching process. In addition, incubation temperatures need to be adjusted to allow a longer development time for the embryo to attain an adequate level of maturity to survive the plateau stage in oxygen consumption or to prevent the use of limited energy of the yolk to survive the anoxia of tucking and internal pipping. The optimal incubation temperature of ostrich eggs appears to be between 36.1 and 36.9 C.

Physiological Differences in Late Embryos from Turkey Breeders at Different Ages

Physiological mechanisms were measured in embryos from turkey hens of different ages to determine associations with declines in hatchability as breeder hens age. As the hens aged from 32 to 54 wk of age, embryonic viability declined (P < 0.05). The greatest proportional increase (P < 0.01) in embryonic mortality of aging hens occurred at the plateau stage in oxygen consumption or immediately thereafter at pipping. Eggshell conductance constants increased (P < 0.01) as hens aged but did not change after mid-lay, suggesting an alteration in respiration for the embryos in eggs produced by older hens compared to eggs produced by the same hens at younger ages. The alteration may cause embryos in eggs from older hens to reach the plateau stage in oxygen consumption (approximately 25 to 26 d of incubation) earlier in development than embryos from young hens. Hepatic and cardiac glycogen concentrations were greatest (P < 0.001) in embryos from hens at the youngest age and then declined (P < 0.05) as the hens aged. Embryonic blood plasma glucose concentrations declined (P < 0.05) similarly. Plasma thyroxine (T4) and triiodothyronine (T3) concentrations were measured in embryos from the hens at different ages as well. Increased (P < 0.05) T4 was evidenced in embryos from the youngest hens, whereas increased (P < 0.05) T3 activity was evident in embryos from hens of older ages. It was concluded that the decline in hatchability seen as turkey breeder hens age may have a basis in the differences seen in the physiology of hatching in embryos. Specifically, thyroid influences on growth and carbohydrate metabolism may be involved in decreased embryonic viability.

Hematological Indices of Turkey Embryos Incubated at High Altitude as Affected by Oxygen and Shell Permeability

Turkey eggs (Meleagris gallopavo) were incubated at altitude of 1,707 m to test the effects of oxygen supplementation and increased eggshell permeability by removal of shell cuticle on embryonic hematology. Turkey embryo hematological indices measured were red blood cell count (RBC), hemoglobin concentration, packed cell volume, mean cellular volume, mean cellular hemoglobin, and percentage of reticulocytes. Although hemoglobin concentration measured during pipping increased as expected by increasing RBC, no significant differences were observed between oxygenation, or permeability treatments, or their interaction. Under the high altitude conditions of the present experiment, increased hemoglobin concentrations in all treatments corresponded to increased numbers of erythrocytes with constant mean cellular hemoglobin. None of the remaining hematological indices examined was affected by oxygen or permeability treatments. It was concluded that turkey embryos incubating at 1,707-m elevation make no additional changes in hemoglobin concentrations during the plateau stage in oxygen consumption (25, 26, and 27 days of incubation) when exposed to increased oxygen tension (151 mm Hg versus 135 mm Hg) or increased eggshell permeability (19.9 mg H2 O/day per mm Hg versus 23.2 mg H2 O/day per mm Hg).

Comparisons of turkey embryos incubated in tenuous or dense gas environments—II. Organ growth

1. 1. Eggs from large white turkeys were incubated in tenuous and dense gas atmospheres. 2. 2. Tenuous gases resulted in heavier embryos until the onset of the plateau stage in oxygen consumption when dense gas environments caused heavier embryos. 3. 3. Tenuous gases decreased heart and lung weight but increased liver weight. 4. 4. Oxygen supplementation in tenous gases increased liver weights but had no effect on lung or heart weights. 5. 5. The data suggest an interaction of gas density and partial pressures of individual gases which affects breathing and the physiology of developing poult embryos.

Water Balance in Incubating Turkey Eggs

The eggshell water vapor conductance capable of maintaining constant water content in incubating turkey eggs was determined for three different egg weight classifications. Metabolism of the developing turkey embryos was altered by increasing or decreasing eggshell permeability. Eggshell permeability accommodated metabolic water in large eggs very well. Both relative poult weights and relative water content of embryos in large eggs at the plateau stage in oxygen consumption decreased or increased allometrically to the permeability treatment. However, among small and medium eggs, if eggshell permeability was increased, relative poult weights at hatching were much less than expected. This occurred despite the fact that relative water content of the eggs at 25 days of incubation was not similarly affected. The data suggest a biological asynchrony for egg size, metabolism, and water content of turkey eggs.