Hy-Line Brown Research Articles

Physical and mechanical properties of eggshell as affected by chicken breed and flock age

ABSTRACT1. A study was conducted to evaluate the relationship among physical and mechanical properties of the eggshell, as affected by breed and hen’s age.2. Data on eggshell quality (external characteristics and derived measurements) were obtained from 322 laying hens, from three breeds (Fayoumi, Dandarawi and Hy-Line Brown) during the laying cycle, starting from 38 wks of age for four experimental periods (38, 46, 54 and 62 wks).3. Eggs obtained from the Fayoumi breed exhibited the highest shell thickness and breaking force. There was a linear improvement in eggshell quality attributes associated with hen’s age up to 54 wks, thereafter a deterioration was found for all breeds.4. Generally, eggs laid by native breeds (Fayoumi and Dandarawi) had better mechanical properties compared to those produced by the commercial strain (Hy-Line Brown). In addition, the interaction between breed and hen’s age was not significant for any physical property or mechanical attribute. There was a highly significant (P ≤ 0.01) positive correlation between the breaking force and either eggshell toughness or shell thickness, and regression analyses suggested that eggshell toughness was the best predictor for breaking force, followed by shell thickness.

Establishment of Hy-Line commercial laying hen whole blood gas and biochemistry reference intervals utilizing portable i-STAT1 clinical analyzer

Blood gas and biochemistry reference intervals were established for 3 genetically distinct commercial varieties (CVs) of Hy-Line laying hens: 2 brown-egg layers (Hy-Line Brown, Hy-Line Silver Brown) and a tint-egg layer (Hy-Line Sonia) utilizing the i-STAT1 analyzer. Each respective variety of laying hen was sampled on a replicate cycle of 2 wk for a total of 6 replicates (35 to 46 wk of age). Blood samples were obtained in the production house from the brachial vein, and subsequently analyzed by the i-STAT1 portable device. i-STAT1 clinical analyzer reports blood gas and biochemistry values for the following parameters: pH, partial pressure of carbon dioxide (pvCO2, mm Hg), partial pressure of oxygen (pvO2, mm Hg), bicarbonate (HCO3, mmol/L), base excess (BE, mmol/L), saturation of oxygen on hemoglobin (sO2%), glucose (Glu, mg/dL), sodium (Na, mmol/L), potassium (K, mmol/L), total concentration of carbon dioxide (TCO2, mmol/L), ionized calcium (iCa, mmol/L), hematocrit (Hct % packed cell volume [PCV]), hemoglobin (Hb, g/dL). A total of 1,800 individual hen i-STAT1 records were utilized in the establishment of reference interval values for the 13 parameters between the 3 CVs. Statistical analysis via ANOVA and Tukey's test revealed significant line differences for all 13 blood gas and chemistry parameters measured, with particularly interesting results in iCa. The blood gas and chemistry parameters collected in this study will serve as reference intervals to set the framework for potential future correlations to genetic markers, physiological abnormalities, and production performance.

Effects of dynamic feeding low- and high-methionine diets on the variation of glucose and lipid metabolism-related genes in the liver of laying hens

We examined the effects of dynamic feeding low- and high-methionine diets on the transcriptional level of glucose and lipid metabolism-related genes in the liver of laying hens. A total of 180 laying hens (Brown Hy-line, 41 wk old) were exposed to 16 h of light and 8 h of darkness with lights on at 06:00h local time (Zeitgeber time [ZT] 0) and allocated into 3 equal groups with 6 replicates. The control group was fed a 0.30% methionine diet. The low-high (LH) group was fed 0.27% methionine diet at ZT1.5 and 0.33% methionine diet at ZT8.5. The feeding regime in high-low (HL) group was opposite to that of the LH group. After 10 wk, a total of 108 hens (6 hens/group/time point) were randomly and equally selected for further analysis. Blood and liver tissues were collected at ZT21.5, ZT1.5, ZT5.5, ZT9.5, ZT13.5, and ZT17.5. The results showed that the serum ALP activity in the HL group was the highest at ZT9.5 and ZT13.5, and that the serum glucose content in the HL group was lowest at ZT21.5 compared to the other 2 groups (P < 0.05). The mesors, amplitudes, and acrophases of the cosine curves for the CLOCK, BMAL1, CRY1, PER2, and PER3 genes were altered in the LH and HL groups. G6PC3, PCK2, GPAT, INSIG2, FASN, ACACA, ACOX1, HMGCR, LDLR, and PPARA expression in the liver were affected by the feeding regime at some time point (P < 0.05). Two-way analysis of variance comparisons showed some significant effects of time on the mRNA expression of G6PC3, G6PC2, PCK2, FBP1, FBP2, GCK, GYS2, FASN, GPAT, HMGCR, LDLR, ACC, SREBP2, and INSIG1 (P < 0.05). Moreover, different feeding regimes significantly affected the expression of FASN, GPAT, HMGCR, LDLR, ACACA, SREBP1, and INSIG1 (P < 0.05). In conclusion, dynamical feeding low- and high-methionine diets affected the variation of serum ALP and glucose levels, as well as the mRNA expression of circadian clock- and glucose and lipid metabolism-related genes in the liver of laying hens.

Daytime occupancy of resources and flooring types by 4 laying hen strains in a commercial-style aviary

In response to consumer demands and legislative measures for improving hens' welfare, many laying hen producers are replacing conventional cages with aviaries. Aviary resources, such as nest boxes, litter areas, ledges, and perches, are intended to increase the display of natural behaviors. However, commercial laying hen strains have been differentially selected for varying traits including egg quality, feed efficiency, and behavior. Therefore, the assumption that laying hens are using the given resources similarly, irrespective of their genetic strain, may be false. This research examined the influence of laying hen strains (brown hens: Hy-Line Brown, Bovans Brown; white hens: DeKalb White and Hy-Line W36) on resource or flooring substrate occupancy (litter areas, nests, elevated wire tiers, ledges, and perches) inside aviaries during peak lay (25 to 28 weeks of age), and whether this occupancy changed in response to litter access. Live observation and video-recording of hens' distribution among different resources were conducted at 3 different times (morning, midday, and evening) for 3 consecutive days, immediately before (PRE), immediately after (IMM), and 3 weeks after (ACC) hens gained access to litter. Observations were conducted in 16 aviary units; 4 units/strain, 144 hens/unit. Data were analyzed in R using generalized linear mixed model with Tukey's post hoc test and α set at 0.05. More brown hens were in nests than white hens during morning across all periods (PRE; P = 0.002, IMM; P = 0.012, and ACC; P = 0.015), but more white hens were recorded in nests than brown hens during midday of all periods (PRE; P = 0.026, IMM; P = 0.028, and ACC; P = 0.024). More white hens were on litter compared with brown (P = 0.002), particularly when litter was first accessible. White hens occupied the open litter area in larger numbers than brown hens during midday and evening of IMM and ACC periods (P ≤ 0.05). Brown hens occupied the underneath litter area in larger numbers than white hens during midday and evening of the ACC period (P ≤ 0.05). Throughout the day, brown hens occupied wire floors in higher numbers than white hens, whereas the latter occupied both ledges and perches more (all P ≤ 0.05). These strain differences suggest that specific aviary designs may be best suited to specific hen strains.

Impact of cuticle quality and eggshell thickness on egg antibacterial efficiency.

The cuticle is the first barrier against bacterial trans-shell penetration. To evaluate the cuticle quality among different colored eggshells, an efficient and reliable method is proposed in this paper on the basis of the opacity theory. It is shown that the Spearman's rank correlation coefficients between the proposed opacity method and the reported reflectance and ΔE*ab methods are all more than 0.90 in measuring the cuticle deposition for the same breed eggs, indicating that the result measured by the opacity method is credible. In addition, the validity of opacity method is also verified by the Escherichia coli penetration experiments performed on the eggs of Dwarf Layer (tinted-shelled), Hy-Line Brown (brown-shelled), and White Leghorn (white-shelled) birds. Results show that the Dwarf Layer eggs, with the thickest cuticle deposition, have the lowest bacterial penetration ratio than the eggs of the other 2 investigated breeds. We found that eggshell thickness is another important factor influencing bacterial penetration apart from the cuticle. Therefore, enhancing cuticle deposition and eggshell thickness would significantly improve the eggs' antibacterial efficiency. It is found that the antibacterial efficiency will reach as high as 98% in such a case where the cuticle opacity is over 27.5% and the eggshell is thicker than 340μm. No significant difference was found in pore density between the penetrated and non-penetrated eggs. Moreover, according to the data for 3 regions of the penetrated eggs, we found that the sharp end shows the highest proportion of bacterial contamination compared with the blunt end and equator. The cuticle quality at equator shows a strong positive correlation between the blunt and sharp end (r2 = 0.8 and 0.7, respectively, P < 0.05). The cuticle at the equator can be selected as an indicator for cuticle breeding to improve the cuticle quality at the blunt and sharp end simultaneously. These results are of significance for the improvement of egg quality and safety in modern commercial breeding.

Effect of layer genotype on physical characteristics and nutritive value of organic eggs

ABSTRACTThe aim of the study was to evaluate the quality of organic eggs from hens of different genotypes and ages. The study investigated the physical characteristics, nutritive value and foaming properties of egg whites from Hy-Line Brown commercial layers, native Greenleg Partridge hens included in the conservation program, and Araucana hens laying blue-shelled eggs. Genotype had an effect on egg weight, albumen height and Haugh units. The vitamin A content of egg yolks was greater for Greenleg Partridge compared to Hy-Line Brown hens (P < 0.05). The n-6/n-3 PUFA ratio in egg yolks from Greenleg Partridge hens was lower, while the EPA, DHA and PUFA n-3 content were higher than in egg yolks from Hy-Line Brown hens (P < 0.05). Egg yolk cholesterol concentration was similar for the studied hen breeds (P > 0.05). Layer age had a significant effect on egg weight, yolk weight and color, and the presence of meat and blood spots (P < 0.05).

The Effect of Grape Seed Extract and Yeast Culture on Both Cholesterol Content of Egg Yolk and Performance of Laying Hens

SUMMARY This study was conducted to investigate the effects of grape seed extract (GSE) and yeast culture (YC) on average daily feed intake (ADFI), feed/egg ratio (F/E), laying rate, average egg weight (AEW), and cholesterol content of egg yolk in laying hens. A total of 640 “Hy-Line Brown” laying hens aged 25 wk were assigned to 4 dietary treatment groups in a completely randomized design. Each group consisted of 5 replicates with 32 layers. The preliminary test lasted for 6 d and the experiment lasted for 48 d. Laying hens in group 1 were fed with basal diet as a control group, and laying hens in groups 2–4 were fed with basal diet supplemented with GSE, YC, and GSE+YC, respectively. The results showed that cholesterol content of egg yolk was significantly reduced by diets supplemented with GSE and GSE+YC (P 0.05). This study demonstrated that GSE and YC had no obvious effect on ADFI and F/E of laying hens, but significantly influenced the laying rate, AEW, and cholesterol content of egg yolk.

Analysis of a genetic factors contributing to feathering phenotype in chickens.

In the current study, we sought to determine whether or not the endogenous retroviral ev21 influences feathering type of chickens, and if one mutation locus in the unoccupied repeat (UR) region can be used to predict the corresponding feathering type and genotype. The distribution of ev21 as well as the mutation locus in UR and occupied site (OR) regions was detected in HY-line gray progenitor (HYGP) 4 lines, HY-line brown (HYB) and Taihang chickens (TH). Furthermore, a detection method for the genotype resulting in late feathering (LF) phenotype was developed by double PCR using C line of HYGP, C line of Dawu progenitor, commercial line of HY-line gray (HYG) males, LF males of TH and Bashang long-tail chickens (BS). Results indicated that a product of 7590bp from the long fragment amplification was observed to be a partial segment of ev21, and was linked with the LF phenotype in HYGP but not in HYB and TH chickens. A total of 2 of 35 males and 10 of 29 females of TH LF chickens were found to be ev21 negative. HaeIII RFLP mutations of 1450bp of UR, 1440bp of OR, and 538bp in the UR and OR common region were analyzed, and genotypic features at the locus correlated with the feathering type phenotype in HYGP, but exhibited no significant effects in HYB and TH chickens. The cut-off of relative intensity of 857 and 1305bp from the double PCR for distinction between homozygous and heterozygous LF males was 1.37. In conclusion, ev21 and the HaeIII RFLP patterns within the locus in UR cannot be used for prediction of feathering type phenotypes in Chinese heritage chickens. However, the partial duplication of PRLR and SPEF2 were able to predict the LF phenotype. Therefore, the double PCR detecting products of 857 and 1305bp described herein could be used for the accurate identification of genotypes influencing feathering type.

Effects of Different Selenium Sources on Laying Performance, Egg Selenium Concentration, and Antioxidant Capacity in Laying Hens.

Supplementation of selenium (Se) is a common practice in the poultry industry via sodium selenite (SS) and selenium yeast (SY), while the effects of nano-selenium (NS) on laying hens are poorly known. This study aimed to compare the effects of NS, SS, and SY on productivity; selenium (Se) deposition in eggs; and antioxidant capacity in laying hens. A total of 288 30-week-old Brown Hy-line laying hens were randomly assigned into four dietary treatments, which included corn-soybean meal basal diet (Con) without Se sources and basal diets supplemented with 0.3mg Se/kg as SS, SY, or NS, respectively. The results exhibited that Se-supplemented treatments achieved greater egg production, egg weight, and daily egg mass, also better feed conversion ratio than Con group (p < 0.05). Se supplementation significant increased egg Se concentration and decreased the egg Se deposition efficiency (p <0.05), while SY or NS supplementation had higher Se deposition efficiency than SS group at 35days (p < 0.05). Moreover, serum glutathione peroxidase (GSH-Px) activity increased in SS or NS group compared to Con group (p < 0.05). The glutathione peroxidase 4 (GPX-4) mRNA levels in liver were significantly higher (p < 0.05) in SS or SY group than in NS group, and mRNA levels of the methionine (Met) metabolism gene glycine N-methyltranserfase (GNMT) were markedly upregulated (p < 0.05) in SY group compared to SS or NS group. Taken together, the results revealed Se from SY is deposited into eggs more efficiently than Se from NS or SS, probably via enhancing the route of Met metabolism. Meanwhile, it might be concluded that SS or SY supplementation directly regulated GSH-Px activity via enhancing GPx4 level, whereas NS via GPx1, thus affecting body oxidation and development.

Effect of Alternative Housing System and Hen Genotype on Egg Quality Characteristics

The aim of the study was to determine the effect of type of alternative housing system and layer genotype on the quality of table eggs. The investigated eggs came from native Greenleg Partridge hens (Z-11) and Rhode Island Red hens (R-11) covered by the gene-pool protection program, as well as from Hy-line Brown commercial hens from litter barn (LS), free range (FR), and organic systems (OS). Eggs for the study were collected from the hens at 56 wk of age. Egg quality assessment was based on the following values egg traits: weight, shape index, yolk, albumen, and shell percentage in the whole egg; eggshell traits: color intensity, weight, thickness, density, breaking strength, physical features of egg content: albumen height, value of Haugh units, yolk color; presence of meat/ blood spots and cholesterol, higher fatty acids, vitamin A and E in egg yolks. In the rearing systems under study, eggs with the highest weight were laid by commercial hens, and the type of alternative rearing system had no significant effect on this trait. Shell colour intensity depends on the breed of hen, whereas the rearing system has no significant effect on this trait. Hen genotype and housing system had an effect on egg shell weight, thickness, and density. The housing system influences the content of MUFA, PUFA, PUFAn-6 and PUFAn-3 as well as PUFA 6/3 in egg yolks. No effect of the housing system on egg yolk cholesterol content was observed.

Mineral content of eggs differs with hen strain, age, and rearing environment

Egg nutrient quality is strongly influenced by hen diet but is also affected by rearing environment, hen strain, and hen age. The objective of the current study was to determine the effect of: 1) conventional battery cages, 2) enrichable cage systems, 3) enriched colony housing, 4) cage-free, and 5) free-range rearing systems on mineral concentrations of whole, dried egg (yolk and albumen combined) from TA Tetra White (TW) and Hy-Line Brown (HB) hens at 44, 68, and 88 wk of age. We hypothesized that mineral concentration of eggs would differ among rearing systems but not between strains or with hen age. Hens held in enriched colony housing systems produced eggs with 10% lower Mg and 11% lower Mn levels than conventional hens. Concentrations of Ca and Cu were higher (7 and 8%, respectively) in eggs from TW hens than from HB hens. Eggs from HB hens had 8% higher concentrations of Fe, 6% higher Mg and 5% higher Mn than TW hens. Mn was higher in eggs from 44-wk hens than from 68- or 88-wk hens (16 and 11%, respectively). Interaction effects between rearing environment and hen age were observed for K and Mn concentrations. Eggs from 68-wk hens in conventional rearing systems contained 14 to 21% more K than eggs from conventional hens at 44- and 88 wk and 14 to 18% more than eggs from 68-wk hens in other rearing systems. At 88 wk of age, hens in conventional rearing systems produced eggs with higher Mn concentration than hens in enrichable or enriched colony housing systems (22 and 23%, respectively). Interactions between rearing environment, hen strain, and hen age were observed for egg Zn levels among 44- and 68-wk hens but were not detectable among 88-wk hens regardless of rearing system or hen strain. Observed differences in egg mineral content in our study were small and are unlikely to have substantial impact on human nutrition.

Effects of Modified Palygorskite Supplementation on Egg Quality and Mineral Element Content, and Intestinal Integrity and Barrier Function of Laying Hens.

This study was conducted to investigate effects of modified palygorskite (MPal) supplementation on the laying performance, egg quality and mineral element content, immunity, oxidative status, and intestinal integrity and barrier function of laying hens. A total of 360 52-week-old Hyline Brown hens were randomly assigned into four dietary treatments for a 7-week feeding trial. The birds were fed a basal diet supplemented with 0 (control group), 0.25, 0.5, and 1g/kg MPal, respectively. The supplementation of MPal did not alter laying performance and egg quality among groups. Compared with the control group, MPal inclusion decreased lead (Pb) content in yolks at 49days, and either 0.5- or 1-g/kg MPal supplementation decreased Pb accumulation in yolks at 25days and manganese (Mn) accumulation in yolks at 25 and 49days. The contents of jejunal secretory immunoglobulin A (SIgA), ileal SIgA, and immunoglobulin G were decreased by the dietary 0.5-g/kg MPal supplementation. The supplementation of MPal also decreased malondialdehyde content in jejunum and ileum, and decreased serum diamine oxidase activity of the laying hens at 25 and 49days. The inclusion of 0.5 and 1g/kg MPal enhanced villus height in jejunum and ileum, and also increased the ratio of villus height to crypt depth in ileum. In conclusion, MPal supplementation decreased Pb and Mn contents in yolks, and exhibited beneficial effects on the intestinal immunity, oxidative status, and intestinal integrity and barrier function of laying hens and its optimal dosage was 0.5g/kg.

Effects of halothane on the electroencephalogram of the chicken.

Little is known about the effects of inhalant anaesthetics on the avian electroencephalogram (EEG). The effects of halothane on the avian EEG are of interest, as this agent has been widely used to study nociception and analgesia in mammals. The objective of this study was to characterize the effects of halothane anaesthesia on the EEG of the chicken. Twelve female Hyline Brown chickens aged 8–10 weeks were anaesthetized with halothane in oxygen. For each bird, anaesthesia was progressively increased from 1–1.5 to 2 times the Minimum Anesthetic Concentration (MAC), then progressively decreased again. At each concentration, a sample of EEG was recorded after a 10‐min stabilization period. The mean Total Power (PTOT), Median Frequency (F50) and 95% Spectral Edge Frequency (F95) were calculated at each halothane MAC, along with the Burst Suppression Ratio (BSR). Burst suppression was rare and BSR did not differ between halothane concentrations. Increasing halothane concentration from 1 to 2 MAC resulted in a decrease in F50 and increase in PTOT, while F95 increased when MAC was reduced from 1.5 to 1. The results indicate dose‐dependent spectral EEG changes consistent with deepening anaesthesia in response to increasing halothane MAC. As burst suppression was rare, even at 1.5 or 2 times MAC, halothane may be a suitable anaesthetic agent for use in future studies exploring EEG activity in anaesthetized birds.

Space use by 4 strains of laying hens to perch, wing flap, dust bathe, stand and lie down.

The laying hen industry is implementing aviary systems intended to improve welfare by providing hens with more space and resources to perform species-specific behaviors. To date, limited research has examined spatial requirements of various strains of laying hens for performing key behaviors and none has been conducted within an alternative housing system. This study investigated the amount of space used by 4 strains of laying hens (Hy-Line Brown [HB], Bovans Brown [BB], DeKalb White [DW], and Hy-Line W36) to perform 5 different behaviors in the litter area of a commercial-style aviary. Hens were recorded standing [S], lying [L], perching [P], wing flapping [WF], and dust bathing [DB] on an open-litter area with an outer perch between 12:00 and 15:00 at peak lay (28 wk of age). Still images of each behavior were analyzed using ImageJ software for 16 hens per strain, and maximum hen length and width were used to calculate total area occupied per hen for each behavior. Brown hens required, on average, 89.6cm2 more space for S (P≤0.021) and 81.5cm2 more space for L (P≤0.013) than white hens. White hens used, on average, 572cm2 more space to perform WF than brown hens (P≤0.024) while brown hens used 170.3cm2 more space for DB than white hens (P≤0.022). On average, hens of all strains were wider while perching than the 15cm commonly recommended per hen (e.g., DW: 18.03; HB: 21.89cm), and brown hens required, on average, 3.38cm more space while perching than white hens (P≤0.01). Brown and white hens occupy different amounts of space when performing key behaviors. These differences, along with factors such as behavioral synchrony, clustering, and preferred inter-bird distances associated with these behaviors, should be considered when creating industry guidelines, crafting legislation and designing and stocking laying hen facilities to ensure hens can fulfill their behavioral needs.

Development of locomotion over inclined surfaces in laying hens

The purpose of the present study was to evaluate locomotor strategies during development in domestic chickens (Gallus gallus domesticus); we were motivated, in part, by current efforts to improve the design of housing systems for laying hens which aim to reduce injury and over-exertion. Using four strains of laying hens (Lohmann Brown, Lohmann LSL lite, Dekalb White and Hyline Brown) throughout this longitudinal study, we investigated their locomotor style and climbing capacity in relation to the degree (0 to 70°) of incline, age (2 to 36 weeks) and the surface substrate (sandpaper or wire grid). Chicks and adult fowl performed only walking behavior to climb inclines ⩽40° and performed a combination of wing-assisted incline running (WAIR) or aerial ascent on steeper inclines. Fewer birds used their wings to aid their hind limbs when climbing 50° inclines on wire grid surface compared with sandpaper. The steepness of angle achieved during WAIR and the tendency to fly instead of using WAIR increased with increasing age and experience. White-feathered strains performed more wing-associated locomotor behavior compared with brown-feathered strains. A subset of birds was never able to climb incline angles >40° even when using WAIR. Therefore, we suggest that inclines of up to 40° should be provided for hens in three-dimensional housing systems, which are easily negotiated (without wing use) by chicks and adult fowl.

Dynamic feeding low and high methionine diets affect the diurnal rhythm of amino acid transporters and clock related genes in jejunum of laying hens

ABSTRACTThis study was conducted to investigate effects of dynamic feeding low and high methionine (Met) diets on circadian clock gene expression in jejunum of laying hens. A total of 180 laying hens (Brown Hy-line, 41 weeks old) were allocated into 3 groups with 6 replicates each. The CON group received diet containing 0.30% Met, LH group received low Met diet (0.27% Met) at 07:30 h and high Met diet (0.33% Met) at 15:30 h, while HL group received high Met diet at 07:30 h and low Met diet at 15:30 h. After 10 weeks, jejunum samples were collected at 4 h intervals in a daily cycle initial starting at 07:30 h before feeding. Results showed that dynamic feeding of Met significantly affected the wave of mRNA expression of B0AT1, LAT1, SNAT2, CAT-2, and y+LAT2 by feeding regime during a day (P<0.05). Dynamic feeding of Met also influenced the fluctuation of relative mRNA expression of Clock, Bmal1, Cry1, Cry2, Per2, and Per3 significantly in hens during a day (P<0.05). These results demonstrated that dynamic feeding different Met level diets of hens affected the rhythmic fluctuation of amino acid transporters and may affected intestinal function by influencing the clock-related genes further.

Alterations in apoptotic markers and egg-specific protein gene expression in the chicken oviduct during pause in laying induced by tamoxifen

The aim of this study was to examine the cell apoptosis, gene expression and activity of caspases 2, 3, 8 and 9, and the mRNA expression of selected egg-specific proteins in the chicken oviduct during pause in egg laying induced by tamoxifen (TMX) treatment. The experiment was carried out on Hy-Line Brown laying hens. The control birds were treated subcutaneously with vehicle (ethanol) and the experimental ones with TMX at a dose of 6 mg/kg of body weight. Hens were treated daily until a pause in egg laying occurred and sacrificed on Day 7 of the experiment. Within the oviductal wall, the highest number of apoptotic cells (TUNEL-positive) was found in the luminal epithelium and the lowest in the stroma. The administration of TMX increased the percentage of apoptotic cells in the magnum, isthmus, and shell gland as well as immunoreactivity for caspases 3 and 9. Real-time PCR analysis revealed the segment-dependent mRNA expression of caspases 2, 3, 8 and 9. Treatment of hens with TMX elevated the level of caspase-2 transcript in the infundibulum, caspases 2, 3 and 8 in the isthmus, and caspase-9 in the shell gland (P < 0.05 - P < 0.001). As shown by fluorometric method TMX caused an increase in the activity of caspases 3 and 8 in the magnum, isthmus and shell gland, and the activity of caspases 2 and 9 in the isthmus and shell gland (P < 0.05 - P < 0.01). The expression of ovalbumin, avidin and ovocleidin-116 mRNAs was decreased (P < 0.05 - P < 0.001), ovocalyxin-36 mRNA level tended to increase, and ovocalyxin-32 expression was not affected by TMX. The results obtained indicate that caspases are involved in the chicken oviduct regression during a pause in laying induced by TMX, and estrogen is involved in the regulation of examined caspase expression and activity. The changes in mRNA transcript levels of some examined egg-specific proteins after TMX treatment suggest that there is a relationship between estrogen action and the expression of these genes.

Nest use and patterns of egg laying and damage by 4 strains of laying hens in an aviary system1

Laying hens are strongly motivated to use nests for egg laying, and alternative production systems (e.g., aviaries) provide artificial sites to meet this need and ensure efficient collection of clean, undamaged eggs. However, nests are typically not provided to allow simultaneous use by all hens; therefore, competition or mislaid eggs can result. To understand the influence of strain on laying eggs outside nests and damage to eggs, we compared daily patterns of nests use and egg laying among 4 laying hen strains (Hy-Line Brown (HB), Bovans Brown (BB), DeKalb White (DW), and Hy-Line W36 (W36)). Hens were observed over 3 consecutive days in aviaries with colony nests in the enclosure’s top tier (2 nests/unit, 4 aviary units/strain, 144 hens/unit). The number and location of hens in nests and the number, location and condition of eggs throughout aviaries were recorded. Most eggs (90 to 95%) were laid in nests; however, brown hens consistently laid more non-nest eggs and damaged more eggs than white hens (P ≤ 0.05). Higher nest occupancy by brown hens was correlated with more non-nest and damaged eggs (P ≤ 0.05). In the morning, brown hens occupied more nest space and laid more nest eggs than white hens (e.g., HB vs. DW: 82.97 and 34.66% of space; 91.35 and 68.73% of nest eggs; P ≤ 0.05). At midday, white hens occupied more nest space and laid more nest eggs than brown hens (e.g., HB vs. DW: 28.47 and 15.81% of space; 27.39 and 8.29% of nest eggs; P ≤ 0.05). Brown hens preferred right nest compartments and laid more eggs there, whereas white hens preferred left compartments and W36 laid more eggs there (P ≤ 0.05). These findings indicate that different strains of hens have different patterns of nest use and laying behavior. In brown hens, heavy morning nest use was related to laying eggs outside nests and more damaged eggs, suggesting insufficient space for oviposition in nests. Specific facility design should be matched to hens’ preferences to accommodate behavioral needs of different strains.

EFFECT OF STRAIN, SEASON AND BREEDER'S AGE ON SOME PHYSIOLOGICAL PARAMETERS FOR LAYER DEAD EMBRYO

The effect of breederʼs strain (Hy-line Brown and Hy-line White W36) flock aged (28, 36, 46, 55, 66 weeks of age) and breeding season on some physiological measurements in egg, demand organs, dead supply organs and lymphoid organs were examined. At each age, 10 unhatched eggs from each genotype were examined on embryo weight percentage, Chorioallotoic weight %, albumen pH %, yolk pH %, residual yolk %, pectoral muscles weight %, hatch muscles weight %, heart, liver, lunges, spleen, burse weight percentage. There was a significant difference between layer breeder genotypes for lunges weight percentage the brown was higher (0.84) than the white (0.62). The breeding season had a significant effect on heart, liver, lunges weight percentages in winter higher than summer but yolk pH and residual yolk the summer higher than the winter. Breeder's age significant effect on embryo weight percentage, Chorioallotoic weight %, albumen pH %, yolk pH%, residual yolk %, hatch muscles weight % heart, liver, lunges and burse weight percentage. It could be observed that the genetic differences among layer breeder strain and age of breeders can affect the hatchery performance. Additionally, handling of hatching eggs and incubation management can play a major role to overcome numerous hatching problems. In turn, increasing the production of table eggs and achieves the balance between supply and demand of that strategic commodity in Egyptian market.

Characterization and comparation test of chicken eggs strain isa brown and hyline brown in different areas

This study aims to determine the characterization and comparative test of exterior and interior qualities including egg weight, eggshell thickness, egg shape, air cavity and interior including high albumin, egg yolk, and haugh egg unit from egg strain Isa Brown and Hyline Brown in different areas of Deli Serdang and Langkat regencies, North Sumatra Province in June-July 2017. The eggs used in this study were 400 eggs divided by 100 Isa Brown and 100 Hyline Brown from Denai Village, Pantai Labu Subdistrict, Regency Deli Serdang, then 100 Isa Brown and 100 Hyline Brown from Sei Limbat Village, Kecamatan Selesai, Langkat District. Each egg is collected directly from the chicken and then measured against the exterior and interior. The results showed that the characterization and comparative test of chicken eggs consumption of strains of Isa Brown and Hyline Brown in different regions had results(thit&gt; ttable) with t test on comparative test I1: H1 and I2: H2 meaning egg of different strain showed different result also on egg weight parameter, shapeegg, shell weight, air cavity, egg white index, haugh unit, egg yolk index and yolk color. The comparative test I1: I2 showed no significant differences (thit &lt;ttabel) on egg weight, shell thickness, shell weight, egg white index, haugh unit and egg yolk index, but showed significantly different (titable) results in egg shape, air cavity and yolk color, meaning there is environmental influence but not significant to other quality of egg with same strain in different region. In the H1: H2 comparative test the results were not significantly different (thit &lt;ttabel) on all parameters except the color of egg yolks, meaning that no environmental or strain effect produced eggs of the same quality in different regions.