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The effects of the in ovo administration of vitamin D 3 (D 3 ) and its metabolite, 25-hydroxyvitamin D 3 (25OHD 3 ) , on the performance, breast meat yield, and inflammatory responses of broilers fed commercial diets were investigated. Live embryonated Ross 708 broiler hatching eggs were randomly assigned to one of the following 5 in ovo injection treatments at 18 d of incubation: 1) noninjected; 2) diluent; diluent containing 3) 2.4-μg D 3 , 4) 2.4-μg 25OHD 3 , or 5) 2.4-μg D 3  + 2.4-μg 25OHD 3 . A 50-μL solution volume of each prespecified treatment was injected into each egg using an Inovoject multiegg injector. At hatch, 18 male chicks were randomly assigned to each of 30 floor pens. The BW, BW gain, feed intake, and feed conversion ratio of the birds were determined in each dietary phase. At 14, 28, and 39 d of posthatch age (doa), plasma α-1-acid glycoprotein (AGP) levels in 1 bird in each of 6 replicate pens per treatment were determined at 14 and 39 doa. The pectoralis major and minor weights of those same birds were also determined. The remaining birds were processed at 43 doa, and the weights of their processing parts were determined. At 39 doa, the in ovo injection of 25OHD 3 alone decreased plasma AGP concentrations in comparison with the noninjected, diluent, and D 3 -alone treatment groups. In addition, birds that received 25OHD 3 alone had a greater BW at 42 doa than birds in the noninjected, diluent, and D 3 -alone treatment groups. At 39 and 43 doa, breast meat yield was increased in response to the in ovo injection of 25OHD 3 alone in comparison to all other treatments. These results indicate that the in ovo injection of 2.4 μg of 25OHD 3 resulted in an improvement in the performance and inflammatory responses of broilers. A reduction in the inflammatory response subsequent to the in ovo injection of 2.4 μg of 25OHD 3 may have led to an increase in broiler performance., (Copyright © 2020. Published by Elsevier Inc.)

The embryonic period represents approximately 33 percent of the total productive life of modern broilers and is very important for attaining quality broiler performance at marketing. In this symposium, recent developments in pre-hatch broiler development were discussed with special focus on maternal nutrition, in ovo nutrition, and the regulation and monitoring of the incubational environment. The symposium was concluded with discussion about the implementation of future innovations in incubation technology.

Probiotics can improve broiler performance and reduce pathogens. Because the hatchery can be a source of contamination, delivering probiotics to the embryo before hatch is desirable. To date, probiotics have primarily been injected into eggs manually. Therefore, the objective of this study was to deliver various probiotic bacteria into broiler hatching eggs using an automated commercial in ovo injection system to evaluate hatchability of fertile eggs (HF). Three separate experiments were conducted using Lactobacillus acidophilus, Bacillus subtilis, or Bifidobacterium animalis. In each experiment, 7 treatments (non-injected control; dry punch control; diluent-injected control; and injections of 103 cfu, 104 cfu, 105 cfu, or 106 cfu of bacteria/50 μL of diluent) were evaluated using 10 replicates per treatment. For each experiment, 2,490 eggs were obtained from a commercial hatchery. Eggs were incubated under standard incubation conditions. At 10 d of incubation (doi), eggs were candled, and infertile eggs were removed. On 18 doi, all eggs were injected with the appropriate treatment using an automated in ovo injection system. Once all eggs were injected, they were transferred to hatching baskets and placed into the hatcher. On 21 doi, chicks were removed from the hatcher, counted, and weighed. Hatch residue analysis was conducted to determine infertile, early dead, mid dead, late dead, pipped, cracked, contaminated, and cull chick statuses of all unhatched eggs. Injecting L. acidophilus, even at a concentration as high as 106 cfu/50 μL, did not impact hatch residue analysis (P > 0.05). However, HF was significantly less for eggs treated with B. subtilis than for control eggs (P < 0.0001). For the non-injected control, HF was 91%, but as concentration of B. subtilis increased, HF decreased to as low as 1.67% for the 105 cfu treatment. Late deads, pipped, and contaminated egg percentages were higher, and chick BW was lower for B. subtilis treatment groups compared to controls. In conclusion, L. acidophilus and B. animalis but not B. subtilis, appear to be suitable candidates for in ovo injection as probiotics., (© 2017 Poultry Science Association Inc.)

In a preliminary experiment, the influence of pigment color variation on the temperature readings of the shells (EST) of live embryonated Ross 708 broiler hatching eggs was tested. Prior to set, eggshell color in L*, a*, and b* coordinates were measured at the equator of each egg. Eggshell pigmentation was found not to influence EST from zero through 18 d of incubation (DOI). In a subsequent experiment, EST, as well as air cell (ACT) and cloaca (CLT) temperature measurements were used for the calculation of absolute (GH2O) and specific (gH20) eggshell conductance values for these same types of eggs. An infrared thermometer was used to determine EST from zero to 19 DOI, ACT was measured using a transponder from 12 to 19 DOI, and CLT was determined using a transponder at 4:00 PM at 19 DOI. In the 12 to 19 DOI interval, the values for GH2O as well as for gH20 that were calculated using either EST or ACT were significantly correlated (r ≥ 0.99; P < 0.0001). A similar correlation level for both GH2O and gH20 was likewise observed in the 10:00 AM to 10:00 PM time period at 19 DOI when either EST, ACT, or CLT was used. However, in the 12 to 19 DOI interval, calculated GH2O and gH20 values based on ACT were significantly different from those based on EST. In addition, a significant difference in calculated GH2O and gH20 values resulted when ACT was used rather than when EST or CLT was used in the 10:00 AM to 10:00 PM time period at 19 DOI. In both time periods, GH2O and gH20 values calculated using ACT were significantly lower than those derived using the other 2 types of measurements. These findings suggest that although EST was not affected by shell coloration, because ACT more closely reflects embryo body temperature, it should be used to more accurately calculate the GH2O and gH20 of Ross 708 broiler hatching eggs., (© 2017 Poultry Science Association Inc.)

Relationships between physiological parameters of early posthatch chicks with their corresponding egg and embryo parameters were examined in progeny of young broiler breeders. Four hundred and 80 broiler hatching eggs that were obtained from a 29-wk-old Ross 308 breeder flock were incubated on 8 replicate tray levels of an incubator until hatch. Between 10.5 and 18.5 d of incubation, internal (T(emb)) and external (T(ext)) egg temperatures were recorded twice daily using temperature transponders. Beginning at 18.5 d, the eggs were individually monitored for hatch every 12 h. Average T(emb), T(ext), and average daily incubational egg weight loss (EWL) for the 10.5- to 18.5-d incubation period were used to calculate eggshell water vapor conductance (G(H2O)), specific G(H2O) (g(H2O); G(H2O) adjusted to 100 g of set egg weight basis), and a G(H2O) constant (K(H2O)) for each egg. Chicks were grown out for 10 d in pens of a single battery brooder. In each pen, on d 3 posthatch, carcasses, yolk sac, liver, and pipping muscle samples were collected from at least 2 chicks that hatched from eggs implanted with transponders for determination of their relative weights and moisture concentrations. Livers and pipping muscles were also analyzed for glucose, glycogen, fat, and protein concentrations. Yolk sac weight as a percentage of chick BW (YW) and its moisture concentration (YSM) were positively correlated with T(emb). Egg g(H2O) was positively correlated with chick carcass moisture concentration and its relative weight as a percentage of set egg weight, but it was negatively correlated with YW. The positive functional relationship between T(emb) and incubation length may be mediated via their common positive relationships to YSM. A negative correlation was observed between percentage EWL and relative BW on d 0 and 0.5 posthatch for chicks hatched from unimplanted eggs. The results suggest that a higher g(H2O) results in an increased metabolism of the broiler embryo, which subsequently increases growth and yolk sac absorption in broiler chicks through 3 d posthatch.

The comprehensive profiles of the internal and external temperatures of embryonated Ross × Ross 708 broiler hatching eggs during incubation were determined using temperature transponders, and eggshell water vapor conductance (G(H2O)), specific G(H2O) (g(H2O); G(H2O) adjusted to a 100 g set egg weight basis), and G(H2O) constants (K(H2O)) were calculated. On each of 8 replicate tray levels of an incubator, 2 nonembryonated and 4 embryonated eggs were each implanted with a transponder on d 10.5 of incubation for the determination of internal (air cell) temperatures of nonembryonated (T(nem)) and embryonated (T(emb)) eggs, respectively. In addition, 2 water-filled vials, each containing a transponder, were used on each tray level for the determination of the external microenvironment temperatures (T(ext)) of the embryonated and nonembryonated eggs. Between 10.5 and 18 d of incubation, incubator data logger temperatures were determined every 5 min; and incubator dry bulb temperature, T(ext), T(nem), T(emb), and the difference between T(emb) and T(nem) (T) were determined every 12 h. Over the days of incubation, regression coefficients for T(emb) and T were positive, whereas the regression coefficient for T(nem) was negative. There was a significant day of incubation × type of temperature measurement (T(ext), T(nem), and T(emb)) interaction for temperature. Between 13 and 18 d of incubation, mean values of T(emb) readings that were recorded every 12 h were consistently higher than those of T(ext) and T(nem), indicating the importance of air cell transponder implantation for the efficient estimation of broiler embryo temperature. Furthermore, mean values of the percentage of daily incubational egg weight loss, G(H2O), g(H2O), and K(H2O) of the embryonated eggs were 0.54 ± 0.019%, 14.4 ± 0.56 mg of H₂O/d per Torr, 25.0 ± 0.96 mg of H₂O/d per Torr per 100 g, and 5.20 ± 0.205, respectively. The results suggest that transponders may be implanted in the air cells of broiler hatching eggs to detect incubational variations in T(emb) and to subsequently calculate G(H2O), g(H2O), and K(H2O).

Effects of the in ovo injection of commercial diluent supplemented with dextrin or with dextrin in combination with various other carbohydrates on the somatic characteristics and liver nutrient profiles of Ross × Ross 708 broiler embryos and chicks were investigated. Results include information concerning the gluconeogenic energy status of the liver before and after hatch. Eggs containing live embryos were injected in the amnion on d 18 of incubation using an automated multiple-egg injector for the delivery of the following carbohydrates dissolved in 0.4 mL of commercial diluent: 1) 6.25% glucose and 18.75% dextrin; 2) 6.25% sucrose and 18.75% dextrin; 3) 6.25% maltose and 18.75% dextrin; and 4) 25% dextrin. Also, a noninjected control and a 0.4-mL diluent-injected control were included. Body weight relative to set egg weight on d 19 of incubation (E19) was increased by the injection of all carbohydrate solutions, and on the day of hatch was increased by the injection of diluent, sucrose and dextrin, and maltose and dextrin solutions. Hatchability of the fertilized eggs, residual yolk sac weight, and liver weight were not affected by any injection treatment; however, as compared with the 0.4 mL diluent-injected group, all of the supplementary carbohydrates, except for the glucose and dextrin combination group, increased liver glycogen and glucose concentrations on E19. Furthermore, all carbohydrates, except for the 25% dextrin treatment, decreased liver fat concentration on E19. From E19 to the day of hatch, liver glycogen concentrations dropped dramatically from an average of 3.2 to 0.6%. Despite treatment differences observed on E19 for liver glycogen, glucose, and fat concentrations, these differences were lost by the day of hatch. Nevertheless, liver glycogen and glucose concentrations were positively correlated on the day of hatch. In conclusion, the in ovo injection of various supplemental carbohydrates dissolved in 0.4 mL of commercial diluent altered the liver nutrient profile of Ross × Ross 708 broiler embryos before hatch. However, the subsequent pattern of energy utilization during the hatching process modified these effects.

This study is the first proteomics analysis of the muscularis complexus (pipping muscle) in chicken (Gallus gallus) broiler embryos. We used differential detergent fractionation and nano-HPLC-MS/MS analysis to identify 676 proteins from all cellular components. The identified proteins were functionally classified in accordance with their involvement in various cellular activities., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The effects of the in ovo injection of different carbohydrate solutions on the internal egg temperature (IT), hatchability, and time of hatch of embryonated Ross × Ross 708 broiler hatching eggs were determined. In addition, the BW, liver weight, yolk sac weight (YSW), and yolk-free BW (YFBW) of the embryos on d 19.5 of incubation and of the chicks on day of hatch were determined. Eggs containing live embryos were injected in the amnion on d 18.5 of incubation using an automated multiple-egg injector. Solution injections delivered 1.2 mL of physiological saline (0.85%) alone or with a supplemental carbohydrate. The following supplemental carbohydrates were separately dissolved in saline at a concentration of 0.3 g/mL: glucose, fructose, sucrose, maltose, and dextrin. Temperature transponders were implanted in the air cells of embryonated and nonembryonated eggs after in ovo injection for the detection of IT at 6, 14, and 22 h after injection. The IT of embryonated eggs was significantly greater than that of nonembryonated eggs at all 3 times after the treatment period. Eggs that were injected with saline with or without supplemental carbohydrates experienced a reduction in IT when compared with control eggs whose shells were perforated without solution delivery, and the decrease in IT was associated with a delay in hatch time. Liver weight was negatively related to YSW and positively related to YFBW, and YSW was negatively related to YFBW. Although the saline and carbohydrate solution injections increased chick BW compared with noninjected controls, chick YFBW was decreased in the maltose- and sucrose-injected groups. In conclusion, the injection of 1.2 mL of saline with or without supplemental carbohydrates lowered embryonic metabolism, as reflected by a lower IT and a delay in time of hatch. However, effects of the different carbohydrate solutions on yolk absorption and tissue deposition in yolk-free embryos varied. These results suggest that lower volumes for solutions containing maltose, sucrose, or fructose should be considered for in ovo injection.

The effects of in ovo injection of different carbohydrate solutions on hatchability of fertilized eggs (HF), rate of hatch, BW, body moisture, yolk sac weight, and yolk sac moisture of Ross × 708 broiler chicks, hatched from eggs laid by a 34-wk-old breeder flock, were investigated. Eggs containing live embryos were injected, using an automated multiple-egg injector, in the amnion on d 18.5 of incubation with 0.1, 0.4, 0.7, or 1.0 mL of commercial diluent or a carbohydrate dissolved in diluent. The commercial diluent containing 0.25 g/mL of one of the following carbohydrates was injected into eggs: glucose, fructose, sucrose, maltose, or dextrin. The results showed that no carbohydrate type or solution volume affected rate of hatch. Absolute and proportional BW on day of hatch were positively related to injection volume (P < 0.001). However, HF was negatively related to injection volume (P < 0.001). To realize an HF of 90%, the injection volume could not exceed 0.4 mL for fructose or sucrose and could not exceed 0.7 mL for glucose, maltose, or dextrin. Yolk-free BW was negatively related to injection volume of fructose and sucrose (P < 0.004), but was not related to injection volume of diluent, glucose, maltose, and dextrin. Conversely, absolute and proportional yolk sac weights were positively related to injection volume of fructose, sucrose, and dextrin (P < 0.01), but were also not significantly related to injection volume of diluent, glucose, and maltose. Yolk sac moisture was positively related to injection volume for all injectables, including the diluent (P < 0.03). However, body moisture and yolk-free body moisture were not related to injection type or volume. In conclusion, the use of carbohydrates added to a commercial diluent for the in ovo injection of broiler hatching eggs requires the use of appropriate volumes to promote growth and nutrient utilization without adversely affecting HF.

Effects of the automated in ovo injection of various concentrations and volumes of physiological electrolyte solutions and a carbohydrate-electrolyte solution (CEN) on broiler embryo development and posthatch chick performance were investigated in 5 individual consecutive trials to test potential diluents for commercial injection. A 200-µL saline solution (117 mM) injection treatment and a noninjected control were included in all trials. For the first 4 trials, solutions were injected into the amnion of embryos on d 16 of incubation, and subsequent percentage incubational egg weight loss, embryo mortality, proportional embryo BW, embryo moisture content, proportional yolk sac weight, and yolk moisture content were evaluated on d 18. In trial 5, solutions were injected into the amnion on d 18, and subsequent hatchability and posthatch performance were investigated. In trial 1, a 200-μL injection of 5 mM tripotassium citrate (C(6)H(5)K(3)O(7)) and a 200-μL injection of CEN at 1:400 and 1:8,000 concentrations had no detrimental effect on proportional embryo BW. However, embryo moisture content was increased by the injection of either solution at all concentrations. In trial 2, 200-μL injections of saline, potassium chloride (KCl), or sodium dihydrogen phosphate (NaH(2)PO(4)) solution at various physiological concentrations did not affect any of the parameters examined. In trial 3, the injection of 2,000 µL of 117 mM saline reduced 0 to 18 d percentage egg weight loss. In trial 4, percentage egg weight loss was reduced and embryo moisture was increased by a 200-μL saline (117 mM) injection, but not by 200 μL of solutions of CEN (1:400), C(6)H(5)K(3)O(7) (5.0 mM), or NaH(2)PO(4) (1.0 mM) in 5.5 mM KCl. Compared with controls in trial 5, plasma refractive index was increased by CEN-KCl (1:400-5.5 mM) and saline (117 mM) injections, but not by C(6)H(5)K(3)O(7)-KCl (5 mM-5.5 mM). The current study indicated that 5.5 mM KCl and 5 mM C(6)H(5)K(3)O(7) have the greatest potential for use individually or in combination for the commercial injection of broiler hatching eggs.

Previous techniques that have been used to monitor broiler embryonic temperature and metabolism during incubation either have been invasive to the embryo or have not directly determined internal egg temperature. Therefore, the current investigation was conducted to determine the earliest day of incubation on which temperature transponder implantation in the egg air cell could be performed with minimal invasiveness to broiler embryogenesis. Eggs from young broiler breeder hens (Ross 308; 27 wk of age) were weighed and set on 3 tray levels (approximately 120 eggs per tray level) of a single incubator. Randomly, on each tray level and on each day between d 10 and 14 of incubation, 4 embryonated eggs were assigned to an invasive control (IC) treatment (shell perforation only) and 4 other embryonated eggs were assigned to a transponder implantation (TI) treatment (shell perforation, followed by transponder implantation in the air cell). Four embryonated eggs per tray were also assigned to a noninvasive control treatment on d 10 of incubation. Percentage of embryo survivability through d 18 of incubation, and percentages of mean daily incubational egg weight loss between d 18 and each respective day of implantation were calculated. Furthermore, various internal organ and tissue parameters were examined on d 18 of incubation. Embryo survivability was reduced because of transponder implantation on d 10 and 11 of incubation; however, embryo survivability was not different between eggs in the noninvasive control and IC treatments and the eggs that received the TI treatment on d 12, 13, and 14 of incubation. In comparison with eggs in the IC treatment, those in the TI treatment had a higher percentage of embryo weight. Conversely, yolk sac moisture was significantly higher in IC-treated eggs than in TI-treated eggs. It was concluded that temperature transponders may be inserted into the air cells of broiler hatching eggs between d 12 and 14 of incubation without adversely affecting eggshell porosity or embryogenesis and without causing physiological stress to growing broiler embryos.

The relative proportions and relationships of pipping muscle and liver nutrients in broiler embryos on d 15 and 19 of incubation were determined. Ninety hatching eggs obtained from a 30-wk-old broiler breeder flock were incubated on 3 replicate tray levels (30 eggs per tray) for 19 d. On 15 and 19 d of incubation, 10 live embryos per tray level were necropsied to collect pipping muscle and liver samples. As the broiler embryo developed between d 15 and 19 of incubation, the glycogen and protein concentrations of the pipping muscle increased, whereas those of the liver decreased, and the fat concentration of the pipping muscle decreased, whereas that of the liver increased. Across d 15 and 19, pipping muscle glycogen was negatively correlated with liver fat, whereas on d 15, pipping muscle glucose was negatively correlated with liver fat, and pipping muscle glycogen was negatively correlated with liver glucose and glycogen. Pipping muscle fat was negatively correlated with liver glucose on d 15 but positively correlated with liver glycogen on d 19. In conclusion, in preparation for hatch between d 15 and 19 of incubation, weights of the liver and pipping muscle of broiler embryos increased relative to their BW. This occurred in association with the accumulation of glucose, glycogen, and protein and with the loss of fat in the pipping muscle. The carbohydrate stores in the pipping muscle were supported by the active metabolism of the liver before 19 d of incubation, which included the transfer of glucose and fatty acids to the pipping muscle via the circulation. Despite the liver's active supply of these nutrient subunits for assimilation and oxidation by the pipping muscle, there was an overall accumulation of hepatic fat between d 15 and 19 of incubation. These data suggest that the integrated changes in the energy profiles of pipping muscle and liver between 15 and 19 d of embryogenesis are integral to the broiler embryo's preparation for hatch.

1. Ross 308 broiler breeder hens were given diets containing 0 or 25 mg L-carnitine/kg (8 replications per treatment) from 21 weeks of age. 2. Hens were inseminated with semen from Ross broiler breeder males. In a common facility, subsequent progeny hatchability and embryonic mortality at 25, 30, 32, and 38 weeks of breeder age were evaluated. 3. Subsequent egg component weights, incubational egg water loss, progeny embryo growth, and embryo, yolk sac and liver composition through 18 d of incubation at 27, 32, and 38 weeks of breeder age were evaluated. 4. Calculated additions of L-carnitine were in agreement with analysed contents of 3.5 and 31.1 mg free L-carnitine/kg of diet, respectively, and total L-carnitine concentrations increased by 48.6, 21.7, and 10.0% in 0-d yolk, 18-d yolk sac, and 18-d liver samples, respectively, due to the addition of dietary L-carnitine. 5. Supplemental L-carnitine resulted in increased (0.6%) relative 0-d egg yolk weight across weeks 27, 32, and 38, and reduced (0.38%) 18-d yolk sac palmitoleic acid concentration at week 27 without altering embryogenesis. 6. In conclusion, dietary L-carnitine (25 mg/kg of the diet) was deposited in the yolks of broiler breeder hens and was subsequently transferred to the embryonic liver via yolk sac absorption through 18 d of incubation. Furthermore, dietary L-carnitine supplementation increased ovarian follicle yolk deposition in 27-, 32-, and 38-week-old breeder hens, and influenced yolk sac fatty acid beta-oxidation in embryos from 27-week-old breeder hens causing yolk sac palmitoleic acid concentrations to be reduced by 18 d of incubation.

The objective of this study was to establish relationships among various physiological parameters in early (through 72 h posthatch) nutrient restricted broiler chicks from young breeder hens. Despite a 19% decrease in mean BW between 0 and 72 h posthatch, there were no chick mortalities. Liver glycogen peaked at 24 h, and peaks in rectal temperature, plasma glucose, and plasma refractive index occurred at 48 h. By 24 h, negative correlations were noted between BW and relative liver weight and between liver glycogen and both refractive index and rectal temperature. By 24 h, positive correlations were noted between relative liver weight and liver glycogen, BW and plasma glucose, rectal temperature and plasma glucose, and rectal temperature and body fat loss score. Mean daily relative egg weight loss between 0 and 19 d of incubation (RIEWL) was positively correlated with rectal temperature at 0 h but was negatively correlated with rectal temperature at 24 h and liver glycogen at 24 and 48 h. Furthermore, mean relative hatching chick weight (RHCW) had significantly positive correlations with plasma glucose at 6 h and rectal temperature at 48 and 72 h. Broilers having a greater RHCW after hatching from eggs with a lower RIEWL may maintain higher metabolic rates between 24 and 72 h posthatch despite nutrient deprivation. However, broiler chicks from eggs exhibiting a higher than optimal RIEWL may have greater dependence on gluconeogenesis, thus requiring stricter management during initial brooding.

The effects of broiler breeder age (26, 28, and 30 wk) and incubator relative humidity (43, 53, and 63% RH) on yolk sac weight and composition in broiler hatching eggs between 16 and 19 d of incubation were evaluated. Percentage yolk sac weight was reduced in eggs from the youngest (26 wk) breeder hens and in eggs incubated at 53% RH. Percentage yolk moisture, in eggs from the youngest hens, was lowest at 16 d and was highest at 19 d, and percentage yolk lipid was highest at 16 and 17 d of incubation in eggs from 30-wk-old hens. Percentage yolk lipid content was higher at 63% RH compared with 53% RH in eggs from 26-wk-old breeders but was lower in eggs incubated at a 43% RH compared with 53 and 63% RH from 30-wk-old breeders. Yolk stearic and arachidonic acid concentrations were higher and myristic acid concentration was lower in eggs from the 26-wk-old hens. Conversely, the highest yolk concentrations of linolenic and palmitoleic acids occurred in eggs from 30- and 28-wk-old breeders, respectively. At 16, 17, 18, and 19 d of incubation, yolk oleic acid concentrations were significantly, but variably, affected by breeder age, whereas linoleic acid concentration was highest in 26-wk-old breeders only at 19 d. Palmitic acid concentration at 17 d was lower in eggs incubated at 53% RH compared with 43 and 63% RH. Rate of yolk uptake from the yolk sac by embryos may be increased by incubating eggs at 53% RH, and the effects of changes in RH between 43 and 63% on yolk lipid content are influenced by breeder age.

There is a paucity of information regarding the influence of incubational humidity on the characteristics of broiler embryos from young hens that often produce chicks of marginal quality. Therefore, the effects of broiler breeder age (26, 28, and 30 wk) in young broiler breeders and incubator humidity (43, 53, and 63% RH) on embryonic growth between 16 and 21 d of incubation, hatching chick weight, and embryo and chick body compositions were evaluated. Hatching broiler chick BW at 21 d was lower for 26-wk-old breeders compared to those at 28 and 30 wk, and the lowest RH decreased relative wet embryo weight. Embryonic growth, on wet and DM bases, was increased in eggs from the youngest hens. Embryo moisture content (EM) was lower at 16, 17, and 19 d of incubation in eggs from breeders at 26 wk when compared to those at 28 wk of age. The effects of RH on embryo crude protein and fat composition were not consistent and varied with breeder age and length of incubation. It was demonstrated that broiler breeder age affects embryogenesis and hatching chick BW. Furthermore, EM was influenced by breeder age, and changes in incubational RH between 43 and 63% affected embryogenesis without having associated effects on EM or consistent effects on embryo crude fat and protein content. Nevertheless, a depression in embryogenesis with a reduction in incubational RH to 43% may accentuate poor posthatch performance of chicks from young breeders.

The effects of dietary fat and broiler breeder age on egg and embryo characteristics during incubation were investigated. Breeders were fed diets containing no added fat or 3.0% added poultry fat (PF) for peak energy intakes of 430 and 467 kcal/hen day (pC/d), or 1.5% PF or 3.0% corn oil at 449 pC/d. Feeding of diets was initiated at 22 wk, and eggs were collected for incubation at 27 and 36 wk of age. Percentage incubational egg weight loss was determined between day of set and Days 6, 12, and 18. Percentage wet and dry embryo weights, embryo moisture content, and eggshell weights were determined at 6, 12, and 18 d of incubation. Percentage yolk sac weight and wet and dry liver weights and moisture content were determined on Days 12 and 18. Percentage gall bladder weight was determined on Day 18. There were no observed effects due to breeder diet. However, eggshell weight at Days 6, 12, and 18 was higher in 27-wk-old hens compared with 36-wk-old hens. Conversely, egg weight loss between Day 0 and Days 6, 12, and 18 and yolk sac weight across Days 12 and 18 of incubation were lower in eggs at 27 wk of age compared with 36 wk. At Day 18, dry embryo weight was higher and wet liver weight was lower at 27 wk compared with 36 wk. A slower rate of DM accumulation in embryos at Week 36 compared to Week 27 was associated with increased incubational water loss and decreased embryo moisture content, eggshell percentage, and yolk sac absorption rate. These data demonstrate that changes in eggshell characteristics with broiler breeder age can alone impact yolk uptake, growth, and body composition in subsequent embryos.

Broiler hatching eggs were subjected to one RH condition (53% RH) from 0 to 16 d and switched to one of three different RH conditions (43, 53, or 63%) from transfer at 16 d to pull time at 21.67 d of incubation. The broiler breeder ages were 27, 29, and 31 wk for Trial 1, and 26, 28, and 30 wk for Trial 2 in Experiment 1. For both trials, BW at hatch, BW at pull, hatch time, and chick weight loss between hatching and pull were measured. All unhatched eggs were opened and examined macroscopically. Experiment 2 was conducted using the chicks produced in Experiment 1. The chicks were immediately placed after pull and randomly distributed by sex into brooding pens by RH treatment in Trial 1, and by sex, RH, and brooding temperature in Trial 2. Two brooding conditions, warm and cool, were used in Trial 2. Body weight at placement, BW gain to 12 d, feed conversion, and mortality were recorded. There was no effect of RH treatment on fertile hatchability. Body weight at hatch, pull, and placement increased with hen age. Mortality was higher for the late-hatching chicks in the warm brooding conditions in Trials 1 and 2 of Experiment 2, whereas mortality was significantly greater for the early-hatching chicks and those chicks hatched at 43% RH under the cool-brooding temperature conditions. Relative humidity treatment had no effect on chick performance in the presence of warm brooding conditions. Warm brooding conditions improved BW gain to 12 d compared with cold brooding conditions. Overall, optimal chick performance was achieved at 53% RH. Chick quality problems that may be due to high or low RH during incubation can be ameliorated by proper brooding conditions.

The relationship of albumen height (AH) to the compositions of yolks and embryos in hatching eggs from a young (30 wk of age) broiler breeder flock was evaluated during incubation. On Day 2 of incubation, egg weight, yolk weight, and yolk moisture, lipid, and fatty acid contents were determined in eggs from broiler breeders previously identified as laying eggs of either low or high AH. In addition, egg weight, wet and dry embryo weight, and embryo moisture and protein contents were determined on Days 10, 12, and 16, and embryo lipid content was determined on Days 12 and 16. Yolk and embryo weights were expressed as percentages of sampled egg weight. Egg, yolk, and wet embryo weights, yolk moisture and lipid contents, and embryo moisture, protein, and lipid contents were not affected by AH; however, yolk myristic acid concentration was higher, and yolk linoleic acid concentration was lower, in low AH eggs on Day 2 of incubation. Furthermore, on Day 16, dry embryo weight was significantly higher in low AH eggs. Young breeder hens laying eggs of different AH may also produce egg yolks with different fatty acid compositions. Differences in yolk fatty acid profiles between AH groups during early incubation may impact subsequent embryo DM weight without associated effects on embryo moisture, protein, or lipid contents.

We conducted an experiment to determine the effect of relative humidity (RH) during incubation on characteristics of hatched chicks from eggs produced by young broiler breeders. Eggs were collected for 6 consecutive d, every other week, in each of two trials from broiler breeder flocks at 26, 28, and 30 wk of age. The eggs were randomly distributed in machines according to RH treatments that were 43, 53, and 63% RH from set to pulling time at 21.75 and 22 d of incubation for Trials 1 and 2, respectively. The same dry bulb temperature (37.5 C) was used throughout incubation for both trials. Body weight at hatch, but not BW at pull (removal from machine), increased significantly with increasing RH treatment. The BW at hatch and BW at pull increased with increasing hen age. Percentages of late dead and fertile hatchability were the highest for the 63% and 53% RH treatments, respectively. These data demonstrated that, although a high RH during incubation produced chicks with increased BW at hatch, this extra weight was greatly reduced by time of pull, which suggests a significant rate of evaporation even in the presence of high RH. Further, the high RH appears to have a detrimental effect on embryonic development, as evidenced by the increased percentage of late dead.

The effects of dietary fat and eggshell cuticle removal on egg water loss, embryo growth, and hatchability were determined in eggs from broiler breeder hens at different ages. Hens were fed isocaloric diets containing one of three different types and levels of added fat. In addition, eggs were either left intact or washed to remove the eggshell cuticle prior to set. Cuticle removal increased egg water loss between 43 and 62 wk. Cuticle removal increased relative wet embryo weight at Week 52 and relative dry embryo weight at 52 and 62 wk. Furthermore, at 62 wk, diet and day of incubation interacted to affect wet embryo weight, and diet variably affected dry embryo weight. No treatment differences were observed for cumulative hatchability, rate of hatch, and relative yolk sac weight at Day 19 of incubation. It was concluded that cuticle removal and the addition of fat to breeder diets may influence embryonic growth without having any subsequent effects on hatchability.

In two experiments, the effects of dietary fat and breeder hen age on relative yolk sac weight (RYSW) and total serum cholesterol (CHOL), high (HDLC) and low (LDLC) density lipoprotein cholesterol, triglycerides (TRI), and glucose (GLU) were monitored in broiler embryos and chicks. In Experiment 1, embryos at 18 d of incubation and chicks at hatch were sampled from eggs laid by breeder hens at 26 (young), 36, and 48 wk of age. No dietary effects were noted in either experiment; however, chicks from young hens exhibited elevated serum CHOL, HDLC, LDLC, and lower GLU when compared with chicks from hens at either 36 or 48 wk of age. Additionally, embryos from young breeders displayed a lower RYSW at 18 d of incubation. Conversely, by hatch there was no difference in RYSW among offspring from different aged hens. In Experiment 2, newly hatched chicks were sampled from breeder hens at 36, 51, and 64 wk of age. Dietary effects were also not evident in this experiment; however, chicks from 51-wk-old breeders displayed the highest and lowest serum HDLC and TRI, respectively, compared to the other two age groups, whereas chicks from either 51- or 64-wk-old breeders exhibited higher levels of CHOL than those at 36 wk. Chicks from 64-wk-old breeders displayed an increase in LDLC when compared with the other two ages. These data suggest that serum concentrations of lipids and GLU, and RYSW in 18 d embryos and newly hatched chicks are influenced by hen age and not by added dietary fat.

Preliminary studies were performed to develop a method for using real-time, B-mode ultrasonography (US) to directly image the internal morphology of the chicken egg and developing embryo. Different soft tissue interfaces will reflect US waves differentially. These reflected waves, or echoes are then converted into a two-dimensional image of internal morphology. A major limitation of diagnostic US is its inability to penetrate through gas or hard tissue (bone, shell) interfaces. Methodology development to overcome the acoustic obstacle presented by the eggshell and air cell constituted the initial part of the preliminary study. An acoustical window was achieved by creating a 2-cm fenestration through the large end of the eggshell, then filling the air cell with sterile saline. Morphological features of the yolk and embryo were recorded at 0, 2, 6, 9, 14, and 17 days of incubation. The second part of the preliminary study explores whether the acoustic window, once created, could then be closed, and if closed, whether egg viability could be maintained. A second concurrent trial was conducted with 32 eggs that were fenestrated, imaged, recorded, reclosed, and incubated. Two methods of closure were attempted: one using dialysis membrane and tape; the other using an eggshell allograft. Hatchability was partially retained with both window closure methods.

The influence of creating and closing acoustic windows on embryonic and posthatch development for the purpose of chicken embryogenesis monitoring by real-time ultrasonography (US) was evaluated at 2, 6, 9, 14, and 17 days of incubation. Acoustic windows were closed using either a porous dialysis film and tape (FM) or an eggshell allograft attached with collodion (CP). Results from eggs closed in each manner with and without concurrent nonsterile US examination were compared with two control groups. Window creation reduced hatchability. The hatchability reduction was caused primarily by bacterial contamination. Contamination was more common in the FM eggs than in the CP eggs and was greater in eggs that also underwent US. Hatchability increased and contamination decreased when US was performed closer to hatch. Egg weight loss was increased after Day 6 of incubation in FM + US eggs treated on Day 2 and after Day 9 in all eggs with windows except CP eggs treated on Day 9 and CP + US eggs treated on Days 6 and 9. Hatch weight decreased in chicks from eggs that had windows, particularly in FM eggs.

The effects of eggshell cuticle removal and two levels of incubation humidity 28.3 C [50% relative humidity (RH)] and 30.0 C (55% RH) wetbulb temperature (WB) on embryonic mortality and hatchability were determined from broiler hatching eggs laid during 38, 42, 48, and 54 weeks of age. Variables measured were: egg weight loss during the first 17 days of incubation, hatch at Days 19.5 and 20.5 of incubation, hatch of fertile eggs, stage of embryonic mortality, and chick weight at 21.5 days of incubation. Day 0 to 17 percentage egg weight loss was increased when the incubation humidity was lowered and the loss was greater than that observed after cuticle removal. A greater percentage of chicks hatched on Day 19.5 at 28.3 C than at 30.0 C WB. The percentage hatch of 38-week fertile eggs was improved at the higher humidity; the higher humidity also decreased late dead and increased pipped embryonic mortalities. Cuticle removal decreased early dead and increased late dead mortality. At Week 38 cuticle removal and lower humidity resulted in a decrease in chick weight at 21.5 days of incubation. For Weeks 42, 48, and 54 combined, pipped mortality was increased by higher humidity and late dead mortality was increased by cuticle removal. Water loss from the egg was increased by cuticle removal or by lowering incubation humidity from 30.0 C to 28.3 C WB, or by both, but lowering humidity was more effective. Changes in humidity and cuticle removal may affect vital gas exchange to different degrees.(ABSTRACT TRUNCATED AT 250 WORDS)