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Background: The use of NSAIDs have caused stomach injury by inhibiting endogenous mucosal prostaglandin production. Cucumis melo is reported to possess antiulcer potential. This study investigates the mechanism underlying the antiulcer potentials of Cucumis melo (CUM). Methods: Thirty-five male Wistar rat were randomly assigned to each of seven groups; A(control given water and rat pellets), B(gastric ulcer induced with ibuprofen 400 mg/kg), C (Misoprotol 200 μg/kg), D to G (pretreated with different variation of CUM extract; 25 %, 50 %, 75 % and 100 % at a dose of 1 ml/kg for 3 weeks prior to gastric ulcer induction). Ulcer score, ulcer index and percentage inhibition, total gastric acidity was measured. Antioxidant activities, Malondialdehyde, H+/K+ ATPase, PGE2, TNF-α was done by spectrophotometry. Molecular docking investigation of Cucumis melo compounds against Prostaglandin E2 was carried out. Level of significance was tested at P ≤ 0.05 using Tukey post hoc. Result: Total gastric acidity, ulcer score, ulcer index, MDA, TNF-α significantly decreased after CUM treatment when compared to group B. The percentage inhibition, antioxidant activities, PGE2 concentration was significantly increased in all treatment groups compared to group B. Interactions of selected compounds of CUM with Prostaglandin E2 at various docking pockets showed folic acid has highest binding affinity followed by delta7-avenasterol and codisterol to PGE2 receptor. this study shows that one of the mechanisms by which CUM exhibits its antiulcer potential by enhancing Prostaglandin synthesis and antioxidant capacity. Therefore, Cucumis melo can therefore be explored as novel antiulcer agents.

Indigenous and were used to study genetic diversity and population structure analyses. Polymorphism information content (PIC) values ranged from 0.0 to 0.5, with 21,285 SNP markers (35%) being in the lowest PIC value range (0 to 0.15) while 13,511 (commercial chickens have developed unique adaptations to their environments, which may include nutrition, pathogens, and thermal stress. Besides, environmental pressures and artificial selection have generated significant genome-wide divergence in chickens, as those selection pressures contribute a considerable evolutionary force to phenotypic and genotypic differentiation. Herein, we determined genomic diversity of indigenous chickens from semi-deciduous rainforest (SDR), coastal savannah (CS) and Guinea savannah (GS) agro-ecological zones (AEZs) in Ghana and commercial crossbreds (CC) reared at the Kwame Nkrumah University of Science and Technology (KNUST). We generated SNP markers from 82 chickens (62 indigenous chicken ecotypes and 26 commercial crossbred ecotype) using DArT-Seq technology. A total of 85,396 SNP markers were generated and after filtering the data, 58,353 markers 21%) were in the highest PIC value range (0.45 to 0.50). The CC were more genetically diverse than the indigenous birds, with the highest expected heterozygosity value of 0.220. Between the commercial crossbreds population and the indigenous ecotypes, pairwise FST values were estimated to be 0.105 between CS, 0.096 between SDF, and 0.133 between GS. Furthermore, PCA analysis showed that the CC, SDF and GS chickens clustered together and are genetically distant from the commercial crossbred. We herein show that chickens from the AEZs studied can be considered as one population. However, due the abundance of agro-byproducts in the SDR compared to the CS and GS, chickens from the SDR AEZ had better growth compared to their counterparts. It is suggested that the genetic diversity within the local ecotypes could form the basis for genetic improvement., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

The study assessed chicken egg storage duration and short periods of incubation during egg storage (SPIDES) on embryo development. Eggs samples from 310 eggs from 72-week-old hybrid layer breeder flocks were divided and stored at 16 °C and 75% RH for 1, 4, 7, 10, 14, 17, and 21 days (D). Some eggs were also divided between 14D and 21D alone and stored. One subgroup received heat application for 6 h during storage resulting in 0-h × 14D (control); 0-h × 21D (control); 6-h × 14D (SPIDES) and 6-h × 21D (SPIDES). Storage durations between 1D and 21D did not influence most egg quality parameters. The interaction of storage duration and SPIDES affected initial, final egg weights and egg weight loss. SPIDES eggs recorded heavier wet embryos than non-SPIDES eggs at embryonic days (ED) 4, ED7, ED11, and dry embryo weight at ED11. SPIDES resulted in longer embryos at ED4 and ED11. In 21D stored eggs hatchability was higher in SPIDES compared to non-SPIDES treatments (66.7 vs. 48.3%). The reverse effect of SPIDES occurred in 14D stored eggs. In conclusion, the study shows positive effect of SPIDES in longer stored eggs and could be due to a positive impact on embryo.

Snakebites are rampant in Ghana, especially among the farmers, herdsmen, military recruits, hunters, and rural dwellers, and the antisnake venoms (ASV) use to treat these bites are not locally produced but rather imported, which come with a high cost, lack of constant supply and low specificity. The study was therefore aimed at isolating, purifying, and evaluating the efficacy of monovalent ASV from chicken egg yolk using puff adder (Bitis arietans) venom from Ghana. The major pathophysiological properties of the venom and the efficacy of the locally produced ASV were evaluated. The results showed that the snake venom (LD 50 of 0.85 mg/kg body weight) had anticoagulant, haemorrhagic, and edematic activities in mice which were effectively neutralized using the purified egg yolk immunoglobulin Y (IgY), with two distinct molecular weight bands (∼70 and 25 kDa). The cross-neutralization studies also showed that the venom/IgY mixture (2.55 mg/kg body weight: 90 mg/kg body weight) offered 100% protection to the animals with ED 50 of IgY being 22.66 mg/kg body weight. However, the applied dose (11.36 mg/kg body weight) of the available polyvalent ASV offered 25% protection compared with the 62% protection of the IgY at the same dose. The findings showed successful isolation and purification of a Ghanaian monovalent ASV with a better neutralization efficacy compared with the clinically available polyvalent drug., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: This work was supported by the Postgraduate Research Fund of the College of Science, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi-Ghana., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The present study was conducted to examine the impact of incubation temperature profile on embryonic growth and chick quality post-hatch. Hatching eggs (n = 405) were incubated in a Jamesway PS-5000 single-stage incubator at 37.5°C and 56% RH until embryonic day 14 (ED14). At ED14, 135 eggs each were transferred into 3 identical G.Q.F. MFG. CO incubators, and each set to one of the following incubation temperatures: 36.5°C, 37.0°C, and 37.5°C. Data on eggshell temperature (EST) and embryo quality were collected from ED15 to ED20. At hatch, chick quality and leg bone qualities were assessed. Blood collected from chicks was used to assess hematological and immunological parameters. The remainder of the chicks was reared on standard broiler feed for 8 wk to measure growth performance. Data were analyzed using the SAS Proc. GLM at P ≤ 0.05. The daily EST was higher at 37.5°C incubation temperature compared to 36.5°C and 37.0°C during ED15 to ED21. Chicks of 37.5°C had early external pipping and hatching times compared to 36.5°C. There were no significant differences in external chick quality parameters. The chick leg bone Ca and P levels increased with increasing incubation temperature at day old, 4 wk, and 8 wk. Besides mean corpuscular hemoglobin and concentration, which were higher at 37.5°C compared to 36.5°C and 37.0°C, all blood parameters measured were not different. Bone mineral levels may not be the same as bone development. Therefore, appropriate incubation and nutritional strategies are needed to increase bone development, and broiler growth to reduce leg problems., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Aim: The quality of day-old chicks is a cornerstone to successful poultry production. Chicks with a poor quality start slowly in the field and may have high feed intake, poor growth rate, and poor feed conversion ratio. The current study aimed to assess chick quality challenges encountered from day-old chicks hatched in most commercial hatcheries in Ghana., Materials and Methods: A total of 300 day-old chicks each were obtained from commercial hatcheries in Ghana and Europe. The chicks were labeled as locally hatched broiler day-old chicks (LBDOC) and foreign hatched broiler day-old chicks (FBDOC), respectively. Chicks were reared and monitored from day old to 21 days post-hatch. Sample of chicks (n=25) from each hatchery was euthanized weekly at 1, 7, 14, and 21 days and blood samples collected for analysis. The parameters measured included physical, hematological, immunological, histological, and bacteriological characteristics. All data were analyzed by SAS Proc GLM at p<0.05., Results: The live weight of chicks was higher in FBDOC compared to LBDOC on the 1 st day. The chick length and shank length of FBDOC were longer than the LBDOC. The 7-day chick mortality was 6% in LBDOC as compared to 1.5% in FBDOC. The LBDOC also had a higher wet and dry residual yolk sac percentages as well as higher residual yolk sac fluid volume than the FBDOC. The rate of yolk sac disappearance of the FBDOC was higher than the LBDOC. More than half of the LBDOC had developed navel strings and leaky navel compared to FBDOC. The LBDOC recorded Escherichia coli , Proteus, Streptococcus spp., and Gram-negative bacteria in the residual yolk sac isolated through the 21 days while FBDOC recorded E. coli , Proteus, and Gram-negative bacteria. The intestinal villi count, lengths, width, and surface area were all not significantly different. The blood monocyte levels appeared higher in FBDOC than LBDOC, which give evidence of higher immunity in FBDOC than LBDOC., Conclusion: The results indicate a challenging situation in maintaining the quality of locally hatched broiler day-old-chicks compared to foreign hatched broiler-day-old-chicks. The study demonstrates that chick quality impact goes beyond the physical characteristics of chick weight and chick length, and the higher performance of FBDOC may be influenced by compliance with international hatchery standards and vaccination protocols., (Copyright: © Yeboah, et al.)

This research evaluates the effectiveness of local hatcheries in producing quality broiler day-old chicks in Ghana. A total of 600 Cobb 500 unsexed day-old broiler chicks obtained from 3 local hatcheries were raised for 6 wk with recommended starter and finisher diets from a registered source. The parameters measured included feed intake, body weights, body weight gain, feed conversion ratio, percent mortality, and haemagglutination inhibition test against Newcastle Disease virus and Infectious Bursal Disease virus (IBDv) during the first 2 wk. At the end of the study, 2 birds from each hatchery were selected and slaughtered to assess carcass parameters and primal parts including shank, neck, and head. Data were analyzed using the GLM Procedure of SAS 9.4 at P < 0.05 and LS means separated by the PDIFF of SAS. Results indicated that with the exception of the initial weight of the chicks, all other parameters were not different between the 3 hatcheries. The maternal antibody titre against IBDv was higher for all chicks but the response to Newcastle Disease virus and IBDv was relatively low in 1 hatchery. It could be concluded that the sources of chicks influenced initial chick weight but not the post-hatch performance. There is concern about the maternal antibodies levels of the chicks, which could be due to lack of appropriate and efficient vaccination of chicks., (© 2019 Poultry Science Association Inc.)

The aim of the present experiment was to examine the effect of direct fed microbial (DFM) on egg laying performance and health response of indigenous Ghanaian guinea fowls (Numida meleagris). A total of 216, 9-wk-old guinea keets (already sexed) were randomly assigned to 4 DFM administering treatments. These included control, daily, 3 consecutive days per week, and 7 d repeated every other week at 1.5 mL/L through water for 30 wk. Feed intake, body weight gain, feed conversion ratio, egg weight, yolk weight, egg albumen weight, shell weight, shell thickness, mortality, hematological and serum biochemical parameters were recorded. Birds on daily DFM treatment consumed the least feed (P = 0.007) with an increased weight gain (P = 0.009). Hen-day egg production, eggshell thickness and eggshell weight, albumen weight, albumen height, yolk weight, and yolk height were not different between treatments (P > 0.05). Egg weight was higher in daily supplementation of DFM in water than other treatments (P < 0.0001). Serum albumin was higher (P = 0.024) in daily DFM treatment, whereas serum low-density lipoprotein (LDL) cholesterol concentration was reduced (P = 0.017). The results showed that supplementing DFM daily at 1.5 mL/L of water resulted in increased total proteins and albumin as well as reduced LDL cholesterol. It could be concluded that these health indices increased the quality of guinea fowls eggs and may have improved the hatchability of eggs in the 1.5 mL/L DFM supplementation and there the supplementing DFM daily at 1.5 mL/L is recommended in Guinea fowls to increase hatchling numbers.

Broiler strain, maternal age, and incubation temperature influence embryo metabolism. Hatching eggs were obtained from young (Y; 28 to 34 wk, $\bar{\rm x}$ = 31.2 wk), mid (M; 36 to 45 wk, $\bar{\rm x}$ = 40.5 wk) and old (O; 49 to 54 wk, $\bar{\rm x}$ = 51.4 wk) Ross 708 (n = 88; Experiment 1) and Ross 308 [(n = 45; Experiment 2: (Y; 25 to 34 wk, $\bar{\rm x}$ = 30.5 wk), (M; 35 to 44 wk, $\bar{\rm x}$ = 40.2 wk), and (O; 49 to 54 wk, $\bar{\rm x}$ = 51.6 wk)] breeders. Eggs were stored for 2 to 4 d (18°C, 73% RH), and incubated for 14 d at 37.5°C and 56% RH. At 15 d (E15), 8 fertile eggs per flock age were incubated in individual metabolic chambers at 36.0, 36.5, 37.0, or 37.5°C until E21.5. Each temperature was repeated one additional time. O2 consumption and CO2 production were used to calculate embryonic heat production (EHP). Embryo temperature was measured as eggshell temperature (EST). Initial egg weight was used as a covariate; significance was assessed at P < 0.05. In Ross 708, daily EHP tended to be higher in M and O than Y treatments at E16; EHP of M was higher than Y and O eggs at E18; M and O were higher than O eggs at E19. Incubation at 37.0°C resulted in the highest EHP from E15 to E21, except at E17. Embryos at 37.5°C had reduced EHP beyond E17. Daily EST from E15 to E21 was higher at 37.5 and 37.0°C than at 36.0 and 36.5°C. In Ross 308, daily EST was highest at 37.5°C except at E20. Incubation temperature and EST were highly correlated (R2 = 0.90 to 0.89; P < 0.001). Ross 708 chicks were longer and hatched earlier at 37.0°C than at 36.0 and 37.5°C. EST and EHP increased with incubation temperature in Ross 708. In Ross 308, maternal flock age and incubation temperature did not impact EHP. However, EST was highest at 37.5°C except at E20. Ross 708 was more sensitive to incubation temperature than Ross 308.

The present study was conducted to investigate the effect of intermittent use of direct-fed microbial addition (DFM-"RE3®") on growth performance and health status of indigenous guinea fowls in northern Ghana. One-hundred and eighty day-old guinea keets were randomly assigned to 4 direct-fed microbial (DFM) treatments that included: control, daily, 3 consecutive days per wk (3CDW), and 7 days repeated every other wk (7DREOW) at 1.5 ml/L through water from day 1 to 56 days. Feed intake, body weight gain, and blood hematological and serum biochemical properties were recorded. The treatments had no effects (P > 0.05) on the hematological or serum biochemical properties recorded. Birds on DFM treatments appeared to consume less feed (range: 1,584 to 1,824 g/d) compared to the control (1,870 g/d/head). Birds on DFM treatments daily and 3CDW gained more (P < 0.05) weight (334 to 394 g/d) compared to the control (306.1 g/head) with keets on daily DFM supplementation recording the lowest (P < 0.05) feed conversion ratio. The total blood protein, globulin, lipids, albumin concentrations, and cholesterol concentrations were not affected (P > 0.05) by DFM supplementation. Supplementing birds with 1.5 mL of RE3®/liter of water daily can improve body weight. Further research on immune competence from the spleen, thymus, and bursa fibrosis for evidence of increased immune competence in probiotic administered birds is recommended.

1. Two experiments were conducted to determine the influence of the frizzle gene (F) on the production and quality of chicken eggs kept on village farms in Ghana. 2. In the first experiment, 144 pullets, 72 each of Ff and ff pullets from F1 birds, were compared in a randomised complete block design (RCBD), with three villages and 4 batches of hatch as blocks and the two feather genotypes (Ff and ff) as the treatments. 3. The Ff pullets were superior (P < 0.05) to their ff counterparts in terms of the number of eggs per clutch, egg mass and hen-housed and hen-d rates of lay, whereas age at first egg was lower (P < 0.05) in ff layers compared to Ff ones. 4. The eggs of the F1 heterozygous frizzle (Ff) layers had higher values for albumen height, Haugh unit and yolk height compared with eggs from their normal feathered counterparts. 5. In the second experiment, 144 pullets, 48 each of FF, Ff and ff pullets, were compared in a RCBD, with three villages and 4 batches of hatch as blocks and the two feather genotypes (Ff and ff) as the treatments. 6. The F2 birds with genotypes Ff and FF were better than their ff counterparts in terms of the number of eggs per clutch, egg mass, and hen-housed and hen-d rates of lay. Age at first egg was significantly lower in ff layers compared to FF and Ff ones. 7. The Haugh unit value was higher in the homozygous and heterozygous frizzles compared to the normal feathered ones. 8. The presence of the frizzle gene (F) in egg type chickens led to an improvement in egg production and egg quality traits in village chickens, and the cross-breeding scheme evaluated in this project could contribute to improved productivity.

1. Two experiments were conducted to develop naked neck (Na/na) and normal feathered (na/na) crossbreds and compare their growth performance, linear body measurements and carcass characteristics in the first and second filial generations. 2. In the first experiment, 4 indigenous naked neck males (Na/na) were mated to 36 Lohmann commercial females (na/na) in a ratio of 1:9. The two genotypes (Na/na, na/na) were allocated randomly according to batches of hatch, sire lines and sex to three different villages. 3. In the second experiment, 10 males and 100 females of F1 Na/na birds were selected and mated inter se in a ratio of 1:10. The three genotypes (Na/Na, Na/na and na/na) were compared in a randomised complete block design experiment, with the three villages, hatch and sex as blocks and the three genotypes as treatments. F1 Na/na birds had significantly higher (P < 0.05) feed conversion ratio, body weight, body weight gain, linear body measurements, survivability and carcass yield than their na/na counterparts. 4. In the F2 generation, Na/Na and Na/na birds had significantly higher (P < 0.05) feed conversion ratio, body weight, body weight gain, linear body measurements, survivability and carcass yield compared to their na/na counterparts. 5. The birds showing the naked neck phenotype appeared to show superior performance compared to normal feathered birds and could be exploited for potential utilisation in local poultry production.

It is well known that egg storage reduces embryo performance, but the fundamental reasons for reduced embryo quality remain unclear. The objective of this study was to investigate possible cellular and molecular mechanisms that might reduce embryo quality after egg storage. Broiler hatching eggs were obtained from the Ross 308 broiler strain, divided into 2 groups, and stored (4 and 14 d) under the same temperature and humidity conditions. Samples of the eggs were used to assess embryo quality by determining daily embryo weight (wet and dry) from 4 to 21 d of incubation. To understand possible cellular and molecular mechanisms that might affect embryo quality, blastoderms (unincubated embryos) were isolated from a sample of eggs from each storage group, dissociated into single cells, and subjected to flow cytometry analysis to differentiate between viable, apoptotic, and necrotic cell populations. Quantitative real-time PCR analysis was used to compare the expression of selected apoptotic genes (Bcl-2 homologous antagonist/killer gene, Bcl-2-associated X gene, Bcl-2-related ovarian killer gene, B-cell lymphoma 2 gene, and B-cell lymphoma xL gene) in blastoderms and embryos (6 d old after incubation). Data were analyzed by the MIXED model procedure of SAS (SAS Institute, Cary, NC), with significance set at P ≤ 0.05. After covariance analysis of initial egg weights, the results showed decreased daily embryo weights (wet and dry), an indication of decreased embryo quality that could affect hatch quality. In addition, a decrease in blastodermal cell viability was associated with an increased percentage of apoptotic cell deaths (P < 0.0001). Expression of pro-apoptotic genes (Bcl-2 homologous antagonist/killer gene, Bcl-2-associated X gene, and Bcl-2-related ovarian killer gene) were upregulated at the blastodermal level as the storage duration increased, but all genes were downregulated after 6 d of incubation. This suggests that an increase in egg storage duration could activate mechanisms of apoptotic cell death at the blastodermal level, which may be one of the molecular mechanisms that leads to reduced daily embryonic weight during incubation. Experimental controls capable of reducing the cellular and molecular mechanisms of egg storage should be used to increase embryo quality.

The metabolic response of some galliform embryos to embryonic heat production (EHP) and how incubation conditions have been adjusted to prevent overheating of embryos is well established in broiler breeders. However, the daily metabolic status of turkey embryos has not been studied or established in turkey embryos. The objectives of the current research were therefore to determine the respiratory (eggshell conductance, G) and metabolic status (EHP) of 2 modern turkey genetic strains [Hybrid (H) and Nicholas (N)] and 4 parent flock ages [young (Y, 30 wk), peak (P, 34 wk), mature (M, 55 wk), and old (O, 60 wk)] during incubation. To measure G, moisture loss from 15 eggs/genetic strain per flock age and saturated vapor pressure measured between the eggshell and its immediate environment were used. Daily embryonic O(2) consumption and CO(2) production rates were assessed 6 times each day from embryos of eggs (n = 11 eggs/genetic strain per flock age) incubated in individual metabolic chambers and were used to determined daily EHP. Data were analyzed using the mixed model procedure of SAS at P ≤ 0.05. The results showed that the G values (g/d per mmHg) were significantly different for the interaction between genetic strain and parent flock age (H × Y = 17.71, H × P = 17.53, H × M = 19.73, H × O = 26.46, N × Y = 16.70, N × P = 20.96; N × M = 25.47, N × O = 26.05; P = 0.0227). Daily EHP (mW) was higher in embryos from the O flock than in embryos from the Y flock during all days presented except at 8, 25, and 28 d of incubation (4 d: Y = 1.00, P = 0.93, M = 1.60, O = 1.75; 12 d: Y = 19.0, P = 20.0, M = 21.6, O = 23.4; 16 d: Y = 51.7, P = 60.5, M = 65.9, O = 70.8; 20 d: Y = 129, P = 146, M = 144, O = 155; 24 d: Y = 154, P = 188, M = 167, O = 180; 26 d: Y = 169, P = 199, M = 197, O = 230; and 27 d: Y = 231, P = 265, M = 288, O = 307; P < 0.05). The data showed that metabolic differences existed between embryos from flocks of different ages and that embryos from older flocks were metabolizing at a higher rate and could be subject to overheating, which requires further investigation. On the basis of the data, turkey eggs from flocks of different ages should be incubated separately for optimal physiological performance.

We describe a method of isolating blastodermal cells for characterization through flow cytometry. Particular attention was placed on cell viability and integrity issues faced by conventional protocols. The method allowed us to examine mechanisms behind cellular death. Our protocol was optimized by the spatial resolution of the ImageStream multispectral imaging flow cytometer. Overall, the technique provides both quantitative and qualitative information on blastodermal cells. The methodology was applied to the current biological problem in which prolonged (14 d) versus short-term (4 d) layer egg storage reduces embryo viability. Data were obtained between 3 egg storage treatments (unstored, 4 d, and 14 d); the data were analyzed by the PROC MIXED model procedure of SAS at P < or = 0.05 and least squares means separated by the PDIFF procedure of SAS. The results showed that egg storage increases the rate of cell death by both apoptosis and necrosis. Importantly, our study showed higher percentages of necrosis and late apoptosis in long-term versus short-term stored eggs. The percentage of live cells decreased significantly when eggs were stored for 14 d (71.42 + or - 3.36%) compared with eggs stored for 4 d (83.58 + or - 2.15%). The percentage of early apoptotic cells was not significantly different between the 2 treatments. The percentage of necrotic cells and late apoptotic-necrotic cells was higher in eggs stored for 14 d (16.75 + or - 1.73%; 7.36 + or - 1.53%) versus eggs stored for 4 d (3.56 + or - 1.64%; 2.31 + or - 1.52%), respectively. This could negatively affect embryo survival because of the potential effect that necrosis has on surrounding tissue integrity. The technique will be particularly relevant in studies requiring single cells from chicken blastoderms or as a basis to characterize genes that regulate apoptosis in avian species.

The effect of genetic strain (Ross 308; Cobb 500) and parent flock age [young (29 wk), peak (Ross = 34 wk; Cobb = 36 wk), postpeak (40 wk), mature (45 wk), old (55 wk), and very old (59 wk)] on eggshell conductance and embryonic metabolism were examined. At each flock age, eggs from each strain were incubated for 21.5 d in individual metabolic chambers to measure embryonic O(2) intake and CO(2) output. From these data, the respiratory quotient (RQ) and metabolic heat production were calculated. Data were analyzed by the GLM procedure of SAS at P < or = 0.05. Neither strain nor flock age influenced conductance. Total embryonic O(2) consumption, CO(2) output, RQ, and metabolic heat production over the entire incubation period were not affected by strain. Daily differences existed between strains for embryonic O(2) intake (1, 7, 16, 17, 19, 20 d of incubation), CO(2) output (1 to 4, 16 to 20 d of incubation), and heat production (4, 7, 16 to 19 d of incubation). Embryos from young, mature, old, and very old flocks produced significantly more total embryonic heat over the entire 21 d (1,712, 1,677, 1,808, and 1,832, respectively) than embryos from peak (1,601) and postpeak (1,693) flocks. Average RQ for the entire incubation period was higher in embryos from mature flocks compared with all other flock ages. Daily differences among embryos from different flock ages were shown for O(2) consumption (all but d 8 of incubation), CO(2) production (all but d 7 and 9 of incubation), and heat output. The results showed that genetic strain and parent flock age influence daily embryonic metabolism, especially during the early and latter days of incubation. These daily differences coincide with the days of incubation having a higher incidence of embryonic mortality; these 2 factors may be related. Further investigation into the relationship between embryonic metabolic heat production and mortality during incubation may lead to the development of specific incubation conditions for different genetic strains and flock ages.