Lung growth of the turkey, Meleagris gallopavo: II. Comparison of two genetic lines

Comparisons of lung growth in two genetic lines of turkeys, one unselected and one selected for increased body mass, were used to evaluate the lung's alteration in structure with changes in body form or physiology. Seventy-two male turkeys, 36 genetically selected for early rapid growth and large pectoral musculature, and 36 unselected birds, were killed at 12 different ages to compare lung growth in the two lines. Body weights and lung volumes were determined. A three-level cascade sampling system was used to prepare lung tissue for qualitative and quantitative observation by light microscopy. Allometric equations describing growth of lung volume and lung compartments relative to body weight in two phases (tissue proliferation and equilibrated growth) were compared between lines of turkey for differences in slopes or intercepts. Means of data for 112- and 420-day-old birds were also compared. There were no qualitative histological differences observed between lungs of the two lines of turkey, yet there were morphometric differences in lung growth relative to body weight. During equilibrated lung growth, there was less rapid growth of air and blood capillary volumes and surfaces relative to body weight in the selected than in the unselected turkey. The gas-exchange compartment did not enlarge concomitant with the large increase in muscle mass of the selected turkeys, while large-vessel volume and small-airway volume grew similarly to body weight in both turkey lines. We conclude that the lung of the selected line of turkeys did not show an enlarged gas-exchange compartment relative to the greater body muscle mass, but it did show enlarged vessels and conducting airways.     

Changes in the extents of viable and necrotic tissue, interstitial fluid pressure, and proliferation kinetics in clone A human colon tumour xenografts as a function of tumour size

Abstract. Total, viable and necrotic tumour tissue, tumour cell yields, and colony forming efficiencies were measured in clone A human colon tumour xenografts as neoplasms grew from about 100 mm³ to about 6000 mm³. The volumes of the total, viable and necrotic compartments were fit using the Verhulst equation to obtain estimates of growth rates and maximal sizes of the various compartments (carrying capacities). Additionally, at four discrete tumour volumes (250, 850, 2500 and 5500 mm³), hypoxic percentages, proportions of parenchymal tumour and host cells, interstitial fluid pressures, and proliferation kinetics including measurements of apoptosis were determined. There were interesting relationships between the shapes of the curves for total, viable and necrotic tissue to some of the other endpoints measured. Specifically, the volumetric growth curves for the total and viable tumour tissue compartments were identical to a volume of approximately 1000 mm³, but diverged at larger sizes, with the viable cell compartment exhibiting a smaller carrying capacity. The shape of the growth curve for the necrotic compartment exactly mimicked that for the total volume compartment, but was delayed in time by about 21 days. Similarity in shape to that of the overall tumour volume/necrotic volume curves was also seen for the curve for the increase in interstitial fluid pressure, and for the increase in the size of the host cell compartment. In contrast, the growth of the hypoxic compartment and of the parenchymal tumour cell compartment were similar in shape to that of the viable compartment. These data indicate that these compartments are functionally linked. Marked changes in cell kinetic parameters occurred as tumour size increased from 250–5500 mm³. The labelling index and growth fractions decreased from 0.256–0.125, and 0.77–0.40 respectively, and the cell loss factor increased from 0.52–0.74. The volumetric and potential doubling times increased from 4.3–17.6 and 2.1–4.6 days respectively. The cell kinetic changes could not be clearly related to the changes in shape of either the overall tumour volume or the viable tumour volume.     

Earlier hatching time predisposes Cobb broiler chickens to tibial dyschondroplasia

Fertile eggs from Cobb 500 broiler breeder hens were incubated to provide low starting egg shell temperatures (EST; 36.9°C to 37.3°C) which were gradually increased to 37.8°C during the first 7 to 15 days of incubation compared with eggs incubated with a constant EST of 37.8°C (standard conditions) over the first 18 days of incubation. Time of individual chick hatching (measured at 6 h intervals from 468 h of incubation), chick weight, chick length and yolk weight were measured at take-off and BW was measured at 7, 14, 28, 34 and 42 days of age. Male birds at 34 and 42 days of age were assessed for their ability to remain standing in a latency-to-lie test. At 34 and 42 days, male birds were examined for leg symmetry, foot pad dermatitis, hock bruising and scored (scale 0 to 4, where 0=no lesion and 4=lesions extending completely across the tibial growth plate) for tibial dyschondroplasia (TD) lesions. The lower EST profiles caused chicks to hatch later than those incubated under the standard EST profile. Chicks which hatched at ⩽498 h incubation grew faster over the first 7 days than those that hatched later. There were significantly more birds (only males were studied) that hatched from the lower EST profiles with TD scores of 0 and 1 and fewer with score 4 at 34 days than those hatched under the standard profile. Male birds at 34 days with TD lesions ⩾3 stood for significantly shorter times than males with TD scores ⩽2. Moreover, male birds at 34 and 42 days with TD lesion scores of ⩾3 hatched significantly earlier and grew significantly faster over the first 2 weeks of age than did male birds with TD scores ⩽2. It appears possible to decrease the severity and prevalence of TD in the Cobb 500 broiler by ensuring that the birds do not hatch before 498 h of incubation.     

Waiting for a sign: extended incubation postpones larval stage in the beach spawning California Grunion <Emphasis Type="Italic">Leuresthes tenuis</Emphasis> (Ayres)

Unlike most embryos that hatch on a predetermined timetable, California Grunion Leuresthes tenuis can prolong the embryonic period up to three times longer than the time required for hatching readiness. L. tenuis are teleosts that spawn tidally around the highest spring tides of spring and summer, incubating eggs above the water line. Embryos are competent to hatch in 10 days, however they do not hatch until triggered by an environmental cue, agitation in seawater, as the next spring tides rise. This study examined the growth and survival of L. tenuis embryos and larvae that were all fertilized on the same day, then triggered to hatch after different durations of incubation, up to 35 days post fertilization. L. tenuis embryos that survive extended incubation had decreased yolk reserves and did not advance appreciably in morphological development, even when incubation time was extended to its upper limit. After extended incubation, length of hatchlings was significantly longer than hatchlings from the primary incubation time. Regardless of the duration of incubation, larvae provided food ad libitum grew rapidly and were not significantly different in length at three weeks post hatch. Dry mass increased over time and was not significantly different between larval groups within any post-hatch age. Larval growth and survival after one additional tidal cycle of incubation are not adversely affected, but longer incubation significantly decreases embryonic and larval survival. Large reproductive output, environmentally cued hatching, and plasticity in incubation duration enable L. tenuis to reproduce successfully in the unpredictable sandy intertidal ecosystem.     

Regional lung growth following pneumonectomy assessed by computed tomography.

After pneumonectomy (PNX), mechanical strain on the remaining lung is greatly increased. To assess whether remaining lobes expand uniformly after left or right PNX (removing 42 and 58% of lung mass, respectively), we performed high-resolution computed tomography (CT) scans at 45 ml/kg above end-expiratory lung volume on adult male foxhounds after left or right PNX, which were compared with adult Sham controls. Air and tissue volumes were separately measured in each lobe. After left PNX, air and tissue volumes in the right upper and cardiac lobes increased approximately 2.2-fold above and below the heart, whereas volumes in right middle and lower lobes did not change significantly. After right PNX, air and tissue volumes in the left upper and middle lobes increased 2.3- to 2.7-fold across the midline anterior to the heart, whereas the left lower lobe expanded approximately 1.9-fold posterior to the heart. Regional changes in volume density of tissue post-PNX estimated by CT scan parallel postmortem estimates by morphometric analyses. Data indicate heterogeneous regional distribution of mechanical lung strain, which could influence the differential cellular compensatory response following right and left PNX.     

Adult onset lung disease following transient disruption of fetal stretch-induced differentiation

One of the mechanisms by which adult disease can arise from a fetal origin is by in utero disruption of organogenesis. These studies were designed to examine respiratory function changes in aging rats following transient disruption of lung growth at 16 days gestation. Fetuses were treated in utero with a replication deficient adenovirus containing the cystic fibrosis conductance transmembrane regulator (CFTR) gene fragment cloned in the anti-sense direction. The in utero-treated rats demonstrated abnormal lung function beginning as early as 30 days of age and the pathology progressed as the animals aged. The pulmonary function abnormalities included decreased static compliance as well as increased conducting airway resistance, tissue damping, and elastance. Pressure volume (PV) curves demonstrated a slower early rise to volume and air trapping at end-expiration. The alterations of pulmonary function correlated with lung structural changes determined by morphometric analysis. These studies demonstrate how transient disruption of lung organogensis by single gene interference can result in progressive change in lung function and structure. They illustrate how an adult onset disease can arise from subtle changes in gene expression during fetal development.     

Calcium transport and exchange in mouse 3T3 and SV40-3T3 cells

The kinetics of Ca++ uptake have been evaluated in 3T3 and SV40-3T3 mouse cells. The data reveal at least two exchangeable cellular compartments in the 3T3 and SV40-3T3 cell over a 50-min exposure to 45Ca++. A rapidly exchanging compartment may represent surface-membrane-localized Ca++ whereas a more slowly exchanging compartment is presumably intracellular. The transition of the 3T3 cell from exponential growth (at 3 day's incubation) to quiescence (at 7 days) is characterized by a 7.5-fold increase in the size of the fast component. Quiescence of the 3T3 cell is also characterized by a 3.2-fold increase in the unidirectional Ca++ influx into the slowly exchanging compartment and a 3.6-fold increase in its size. The increase in size of the slow compartment at quiescence may result from a redistribution of intracellular Ca++ to a more readily exchangeable compartment, possibly reflecting a release of previously bound Ca++. In contrast, no significant change in any of these parameters is observed in the proliferatively active SV40-3T3 cells after corresponding period of incubation, even though these cells attained higher growth densities and underwent postconfluence.     

A Meta-Analysis of Experiments Linking Incubation Conditions with Subsequent Leg Weakness in Broiler Chickens

A series of incubation and broiler growth studies were conducted using one strain of broiler chicken (fast feathering dam line) observing incubation effects on femoral bone ash % at hatch and the ability of the bird to remain standing at 6 weeks of age (Latency-To-Lie). Egg shell temperatures during incubation were consistently recorded. Parsimonious models were developed across eight studies using stepwise multiple linear regression of egg shell temperatures over 3-day periods and both bone ash at hatch and Latency-To-Lie. A model for bone ash at hatch explained 70% of the variation in this factor and revealed an association with lower egg shell temperatures during days 4–6 and 13–15 and higher egg shell temperatures during days 16–18 of incubation. Bone ash at hatch and subsequent Latency-To-Lie were positively correlated (r = 0.57, P<0.05). A model described 66% of the variation Latency-To-Lie showing significant association of the interaction of femoral ash at hatch and lower average egg shell temperatures over the first 15 days of incubation. Lower egg shell temperature in the early to mid incubation process (days 1–15) and higher egg shell temperatures at a later stage (days 16–18) will both tend to delay the hatch time of incubating eggs. Incubation profiles that resulted in later hatching chicks produced birds which could remain standing for a longer time at 6 weeks of age. This supports a contention that the effects of incubation observed in many studies may in fact relate more to earlier hatching and longer sojourn of the hatched chick in the final stage incubator. The implication of these outcomes are that the optimum egg shell temperature during incubation for broiler leg strength development may be lower than that regarded as ideal (37.8°C) for maximum hatchability and chick growth.     

Effects of temperature during early life history on embryonic and larval development and growth in haddock

The effect of incubation temperature (2, 4, 6, 8 and 10° C) on haddock Melanogrammus aeglefinus development and growth during the embryonic period and in subsequent ontogeny in a common post‐hatch thermal environment (6° C) was investigated. Hatching times were inversely proportional to incubation temperature and ranged from 20·3 days at 2° C to 9·1 days at 10° C. Growth rates were directly proportional to incubation temperature during both the embryonic and larval periods. There was a significant decline in growth rates following hatch in all temperature groups. Compared to the endogenously feeding embryos, growth rates in the exogenous period declined by 4·4‐fold at 4° C to 3·9‐fold at 8° C, indicative of the demarcation between the endogenous and exogenous feeding periods. Yolk utilization varied from 17 days at 2° C to 6 days at 10° C and followed a three‐stage sigmoidal pattern with the initial lag period inversely proportional to incubation temperature. Time to 50% yolk depletion varied inversely with temperature but occurred 1–1·5 days post‐hatch at all temperatures. Additionally, the period between 10 and 90% yolk depletion also decreased with increased temperature. Overall developmental rate was sequential with and directly proportional (2·3‐fold increase) to incubation temperature while the time spent in each developmental stage was inversely proportional to temperature. Larger embryos tended to be produced at lower temperatures but this pattern reversed following hatch, as larvae from higher temperature groups grew more rapidly than those from other temperature groups. Larvae from all temperatures achieved a similar length (c.total length 4·5 mm) upon complete yolk absorption. The study demonstrated the significant impact that temperature has upon developmental and growth rates in both endogenous and exogenous feeding periods. It also illustrated that temperature changes during embryogenesis had significant and persistent effects on growth in subsequent ontogeny.     

Age-dependent lipid peroxidation in neonatal rat lung tissue.

A unique, age-specific pulmonary lipid peroxidation has been found to occur after incubation of neonatal rat lung homogenates in the absence of any added factors. As measured by the formation of malondialdehyde, lipid peroxidation was not detectable in rat lung homogenates prepared from animals immediately after birth but appeared by the second day and reached a maximum at 5 days of age. The effect gradually disappeared by 20 to 21 days after birth. The addition of NADPH did not enhance lipid peroxidation in the sensitive age group nor did it initiate lipid peroxidation when added to lung homogenates from either 1-day-old or adult rats. The activities and concentrations of various endogenous antioxidants were measured in neonatal lung tissue. When measured in lung tissue obtained from rats during the sensitive age period, no concomitant deficiencies of glutathione peroxidase, glutathione reductase, glucose 6-phosphate dehydrogenase, reduced glutathione, or a-tocopherol were observed. With the exception of α-tocopherol, none of these factors inhibited malondialdehyde formation when added to homogenized lung tissue prepared from 5-day-old rats. α-Tocopherol did inhibit malondialdehyde formation in 5-day-old rat lung homogenates but at a concentration much greater than the endogenous concentration found in adult rat lungs. The 21-day neonatal age period during which malondialdehyde is produced following incubation of lung tissue is similar to the 3-week period immediately after birth reported to be the time of maximum proliferation of rat lung fibroblasts, type 1 pneumocytes and type II pneumocytes.     

Induction of intra- and extra-cellular phospholipids in the lungs of rats exposed to silica.

Intracellular and extracellular compartments of phospholipids in the lungs of rats were examined 28 days after intratracheal injection of silica (200 mg/kg). All compartments containing phospholipids were elevated, but the largest increases were seen in the intracellular and extracellular pulmonary surfactant. Intracellular pulmonary surfactant increased 123-fold from 1.18 +/- 0.65 to 144.9 +/- 53.8 and the extracellular surfactant increased 22-fold from 1.17 +/- 0.04 to 25.1 +/- 7.1 mg per pair of rat lungs respectively. The phospholipid composition of intracellular and extracellular surfactant did not change in response to silica, except for an almost 2-fold increase in the percentage of total phosphatidylinositol in both compartments. The phospholipid content of the lungs increased from 24.9 +/- 4.6 to 268.6 +/- 20.8 mg, with the intracellular and extracellular surfactant accounting for 59.1 and 24.6% of this total increase respectively. These data demonstrate that the major increases in the phospholipid content of the lungs induced by silica is associated with the pulmonary-surfactant system.     

Alveoli increase in number but not size from birth to adulthood in rhesus monkeys

Postnatal developmental stages of lung parenchyma in rhesus monkeys is about one-third that of humans. Alveoli in humans are reported to be formed up to 8 yr of age. We used design-based stereological methods to estimate the number of alveoli (N(alv)) in male and female rhesus monkeys over the first 7 yr of life. Twenty-six rhesus monkeys (13 males ranging in age from 4 to 1,920 days and lung volumes from 41.7 to 602 cm(3), 13 females ranging in age from 22 to 2,675 days and lung volumes from 43.5 to 380 cm(3)) were necropsied and lungs fixed, isotropically oriented, fractionated, sampled, embedded, and sectioned for alveolar counting. Parenchymal, alveolar, alveolar duct core air, and interalveolar septal tissue volumes increased rapidly during the first 2 yr with slowed growth from 2 to 7 yr. The rate of change was greater in males than females. N(alv) also showed consistent growth throughout the study, with increases in N(alv) best predicted by increases in lung volume. However, mean alveolar volume showed little relationship with age, lung volume, or body weight but was larger in females and showed a greater size distribution than in males. Alveoli increase in number but not volume throughout postnatal development in rhesus monkeys.     

Morphogenesis of the laminated, tripartite cytoarchitectural design of the blood-gas barrier of the avian lung: a systematic electron microscopic study on the domestic fowl, Gallus gallus variant domesticus

Formation of a thin blood-gas barrier in the respiratory (gas exchange) tissue of the lung of the domestic fowl, Gallus gallus variant domesticus commences on day 18 of embryogenesis. Developing from infundibulae, air capillaries radiate outwards into the surrounding mesenchymal (periparabronchial) tissue, progressively separating and interdigitating with the blood capillaries. Thinning of the blood-gas barrier occurs by growth and extension of the air capillaries and by extensive disintegration of mesenchymal cells that constitute transient septa that divide the lengthening and anastomosing air capillaries. After they contact, the epithelial and endothelial cells deposit intercellular matrix that cements them back-to-back. At hatching (day 21), with a thin blood-gas barrier and a large respiratory surface area, the lung is well prepared for gas exchange. In sites where air capillaries lie adjacent to each other, epithelial cells contact directly: intercellular matrix is lacking.     

The ventilation distribution of helium-oxygen mixtures and the role of inertial losses in the presence of heterogeneous airway obstructions

The regional distribution of inhaled gas within the lung is affected in part by normal variations in airway geometry or by obstructions resulting from disease. In the present work, the effects of heterogeneous airway obstructions on the distribution of air and helium-oxygen were examined using an in vitro model, the two compartments of a dual adult test lung. Breathing helium-oxygen resulted in a consistently more uniform distribution, with the gas volume delivered to a severely obstructed compartment increased by almost 80%. An engineering approach to pipe flow was used to analyze the test lung and was extrapolated to a human lung model to show that the in vitro experimental parameters are relevant to the observed in vivo conditions. The engineering analysis also showed that helium-oxygen can decrease the relative weight of the flow resistance due to obstructions if they are inertial in nature (i.e., density dependent) due to either turbulence or laminar convective losses.     

Expression profiles of somatotropic axis genes in lines of chickens divergently selected for 56-day body weight

The objective of this study was to evaluate mRNA expression of somatotropic axis genes in chickens divergently selected for high (HWS) or low (LWS) body weight at 56 days of age. Gene expression was measured on days 16, 18, and 20 of incubation, day of hatch, and days 3, 7, 28, and 56 posthatch. Pituitary growth hormone mRNA raised from prehatch to posthatch, with a similar profile in both lines. Liver growth hormone receptor (GHR) mRNA was high during embryogenesis, declined to low levels at day 3 posthatch, and then increased to day 56. Expression of liver insulin-like growth factor 1 (IGF-1) mRNA increased sharply by day 28 in line HWS and day 56 in line LWS. Pectoralis major muscle GHR mRNA was greater in line LWS than HWS. Muscle IGF-1 mRNA declined during embryogenesis, increased posthatch, and declined after day 7. IGF-1 mRNA was 1,000-fold greater in embryonic muscle than embryonic liver. Muscle IGF-1 receptor mRNA was greater in line LWS than HWS posthatch. These results demonstrate that genetic selection for high or low body weight has altered the expression profiles of somatotropic axis genes in a line-, age-, and tissue-specific manner.     

Spatial and temporal variation of the intestinal bacterial community in commercially raised broiler chickens during growth

The objective of this study was to determine whether host, compartment, or environmental specific factors play an important role in the establishment of the intestinal microflora in broiler chickens during growth. This objective was addressed using a 16S rDNA approach. PCR-amplicons from the V6 to V8 regions of the 16S rDNA of intestinal samples were separated by denaturing gradient gel electrophoresis (DGGE). The number of bands in all intestinal compartments increased when broilers grew older, indicating that the dominant bacterial community becomes more complex when chickens age. Each chicken had a unique banding pattern for all locations in the intestinal tract, irrespective of the age of chickens. This suggests that host-related factors affect the establishment of the dominant bacterial community. Banding patterns of intestinal compartments within one chicken were different from each other for broilers older than 4 days, except for both ceca which were highly similar. In 4-day-old broilers, banding patterns from crop, duodenum, and ileum were very similar. We conclude that (unknown) host specific factors play an important role in the development of the intestinal bacterial community in each broiler chicken. Furthermore, compartment-specific factors play an important role in the bacterial development of each intestinal compartment within one chicken.     

Posthatching Development of Vascularization,Arteriovenous Anastomoses and Seromucous Glands in the Avian Nasal Mucosa

The development of blood vessels and growth of different tissue compartments in the avian nasal mucosa were studied in chickens from hatching to 5 months of age. The vascularity of the rostral and middle nasal conchae increased about 4-fold, while there was a progressive decrease in the relative size of the epithelium and connective tissue compartments, during the maturation period. Arteriovenous anastomoses (AVAs) were present already at hatching and their density increased 3-fold during the second week of posthatching development. The seromucous glands form by a process of invagination of the epithelium, which occurs predominantly during the first week after hatching. The glands continue to grow in size and an increasing fraction of the cells becomes mucous-secreting. The observations are discussed in relation to the role of the nasal mucosa in temperature regulation and conditioning of the inhaled air.     

What is the clinical relevance of different lung compartments?

The lung consists of at least seven compartments with relevance to immune reactions. Compartment 1 - the bronchoalveolar lavage (BAL), which represents the cells of the bronchoalveolar space: From a diagnostic point of view the bronchoalveolar space is the most important because it is easily accessible in laboratory animals, as well as in patients, using BAL. Although this technique has been used for several decades it is still unclear to what extent the BAL represents changes in other lung compartments. Compartment 2 - bronchus-associated lymphoid tissue (BALT): In the healthy, BALT can be found only in childhood. The role of BALT in the development of the mucosal immunity of the pulmonary surfaces has not yet been resolved. However, it might be an important tool for inhalative vaccination strategies. Compartment 3 - conducting airway mucosa: A third compartment is the bronchial epithelium and the submucosa, which both contain a distinct pool of leukocytes (e.g. intraepithelial lymphocytes, IEL). This again is also accessible via bronchoscopy. Compartment 4 - draining lymph nodes/Compartment 5 - lung parenchyma: Transbronchial biopsies are more difficult to perform but provide access to two additional compartments - lymph nodes with the draining lymphatics and lung parenchyma, which roughly means "interstitial" lung tissue. Compartment 6 - the intravascular leukocyte pool: The intravascular compartment lies between the systemic circulation and inflamed lung compartments. Compartment 7 - periarterial space: Finally, there is a unique, lung-specific space around the pulmonary arteries which contains blood and lymph capillaries. There are indications that this "periarterial space" may be involved in the pulmonary host defense. All these compartments are connected but the functional network is not yet fully understood. A better knowledge of the complex interactions could improve diagnosis and therapy, or enable preventive approaches of local immunization.     

Effects of streptozotocin-induced diabetes on lung mechanics and biochemistry in rats

Young and adult rats were given a single intraperitoneal injection of 75 mg/kg streptozotocin in citrate buffer and were compared with age- and weight-matched controls that received an equal volume of buffer alone. Studies done 8 wk after the injections showed that final body weight, lung dry weight, lung DNA content, and air and saline lung volumes were significantly lower in both young and adult diabetic rats compared with the controls. In young diabetic rats, volume-pressure (V-P) curves expressed as percent maximal lung volume (%MLV) were shifted downward and to the right of those in young control rats at 5 cmH2O transpulmonary pressure (PL) for air and at 4, 6, and 8 cmH2O PL for saline-filled lungs; specific lung compliance (CL) values obtained from both air and saline V-P curves were significantly reduced, and concentration of hydroxyproline relative to DNA was significantly increased. In adult diabetic rats, V-P curves expressed in %MLV, CL values, and concentrations of protein and hydroxyproline were similar to those in adult control rats. We conclude that in both young and adult rats, diabetic state leads to somatic and lung growth retardation. In addition in young diabetic rats lung distensibility is decreased. An increase in the concentration of some connective tissue proteins may be responsible for the latter observation.     

Effects of oxygen concentration during incubation and broiler breeder age on embryonic heat production,chicken development,and 7-day performance

Older breeder flocks produce eggs with a relatively larger yolk and thereby a higher nutrient availability than young breeder flocks. To optimise nutrient utilisation and embryonic development throughout incubation and posthatch period, embryos originating from older breeder flocks may require a higher oxygen availability. The current study investigated effects of broiler breeder flock age and incubational oxygen concentration on embryonic metabolism and chicken development until 7-day posthatch. Similar sized eggs of a young (28–32 week) or old (55–59 week) Cobb 500 breeder flock were incubated at one of three oxygen concentrations (17%, 21% or 25%) from day 7 of incubation until 6 h after emergence from the eggshell. Posthatch, chickens were reared until 7 days of age. Egg composition at the start of incubation, heat production during incubation, and embryo or chicken development at embryonic day (ED)14 and ED18 of incubation, 6 h after hatch and day 7 posthatch were evaluated. An interaction was found between breeder age and oxygen concentration for yolk-free body mass (YFBM) at ED18. A higher oxygen concentration increased YFBM in the old breeder flock, whereas no difference was found between 21 and 25% oxygen in the young breeder flock. Yolk size was larger in the old compared to the young flock from ED0 until 6 h after hatch. Breeder flock age did not affect YFBM at ED14 and 6 h after hatch nor daily embryonic heat production, but there were some effects on relative organ weights. Chickens of the old compared to the young breeder flock showed a higher weight gain at day 7, but at a similar feed conversion ratio (FCR). A higher oxygen concentration during incubation stimulated embryonic development, especially between 17% and 21% of oxygen, in both flock ages_. Although this growth advantage disappeared at 7 days posthatch, a low oxygen concentration during incubation resulted in a higher FCR at 7 days posthatch. Results indicated that breeder flock age seemed to influence body development, with an advantage for the older breeder flock during the posthatch period. Oxygen concentrations during incubation affected body development during incubation and FCR in the first 7 days posthatch. Although an interaction was found between breeder flock age and oxygen concentration at ED18 of incubation, there was no strong evidence that nutrient availability at the start of incubation (represented by breeder flock ages) affected embryo and chicken development at a higher oxygen concentration.