Hen Age Research Articles

Relationships Between Rearing Enrichments, Range Use, and an Environmental Stressor for Free-Range Laying Hen Welfare.

Enrichments during pullet rearing may improve adaptation and welfare of hens as they move from indoor rearing to a free-range system. Individual variation in outdoor ranging may also affect welfare. This study assessed the effects of rearing enrichments and an imposed environmental stressor on hen welfare and egg quality along with the association of welfare with ranging. Hy-Line Brown® chicks (n = 1,386) were reared indoors until 16 weeks with 3 enrichment treatments including a “control” group with standard floor litter, a “novelty” group that received novel objects that were changed weekly, and a “structural” group with H-shaped perching structures. Pullets were then moved to a free-range system with three replicates of each rearing treatment. Daily ranging was individually tracked from 25 to 64 weeks via radiofrequency identification technology. Individual hen welfare assessments were performed at 25, 33, 43, 56, and 64 weeks and correlated with ranging time prior to these dates. At 44 weeks, the range area was reduced by 80% for 11 days to induce stress. Changes in ranging behavior, albumen corticosterone concentrations and egg quality were evaluated. GLMMs showed significant interactions between hen age and rearing treatment for live weight, number of comb wounds, plumage coverage, and toenail length (all P ≤ 0.003), with the enriched hens showing more consistent live weight at the later ages, fewer comb wounds at 33 weeks, and better plumage coverage at the later ages, whereas the structural hens had shorter toenails as age increased. Plumage coverage showed a positive relationship with range use across most age points (P < 0.0001). Hens reduced ranging time following the imposed stressor but increased their number of visits with the lowest increase by the structural hens (P = 0.03). Significant interactions between rearing treatment and stressor for albumen corticosterone concentrations showed the structural hens decreased concentrations immediately post-stress, but the control and novelty groups increased (P < 0.006). The stressor increased or decreased values of most egg quality parameters across all rearing groups (all P ≤ 0.02). Overall, provision of rearing enrichments and greater range use may have positive impacts on hen welfare.

Effect of Different Percentage of Camelina sativa Cake in Laying Hens Diet: Performance, Welfare, and Eggshell Quality.

Simple SummaryNowadays, it is of primary importance to find alternative and sustainable protein sources for animal feeding, taking into account environmental sustainability and animal welfare and production. Camelina sativa, as an alternative source of protein in animal feeding, seems to be a good candidate, but its use is limited by the presence of antinutritional compounds. In this study, a camelina breeding line with a low level of glucosinolates was tested for 31 weeks, in order to verify if the inclusion of up to 20% of camelina cake, in the diet of laying hens, could have an adverse effect on the production performance, eggshell quality, and animal welfare and health. Results demonstrated that the performance was maintained, as well as health and welfare, while eggshell quality slightly improved when hens got older.Although camelina [Camelina sativa (L.) Crantz] is a good source of protein, antioxidants, and polyunsaturated fatty acids, its antinutritional compounds limit its use in animal feeding. The aim of this study was to verify the effect of feeding laying hens with up to 20% of camelina cake from a breeding line containing a low level of glucosinolates on performance, welfare, and eggshell quality. Two hundred and forty Hy-Line® hens from 18 to 51 weeks of age were divided into three treatments: control (C), camelina cake 10% (CAM10), and camelina cake 20% (CAM20). Egg number was recorded daily, while egg weight, feed consumption, and mortality were recorded weekly. At 24 and 43 weeks of hen age, shell resistance to fracture was measured. Our results demonstrate no detrimental effects for CAM10 and CAM20 diets on feed intake, growth performance, and welfare. No difference in egg production was detected among the diets. The significant (p < 0.05) interaction of diet and age factors suggest that the addition of camelina cake, up to 20%, likely protects the eggshell of older hens. Our findings confirm that camelina cake might be an alternative and sustainable protein source for hens.

Phenotypic Correlation Between External and Internal Egg Quality Characteristics in 85-Week-Old Laying Hens

Background and Objective: Several studies confirm that the age of hens has a tremendous impact on external and internal egg quality characteristics. Egg production could be at serious risk if egg quality characteristics and age of hens are not seriously considered. This study was conducted to analyze the phenotypic correlations between some internal and external egg quality characteristics in old laying hens. Materials and Methods: A total of 288 eggs of 85-week-old Hy-Line Brown laying hens were collected during 3 weeks and their internal and external egg characteristics were evaluated. Results: Phenotypic correlations between egg quality characteristics in old laying hens indicate a negative impact on shell and albumen quality but not affected yolk quality characteristics. Conclusion: This study helps to understand that raising laying hens above 80 weeks would have a negative impact on egg quality characteristics.

Glycerol Monolaurate Enhances Reproductive Performance, Egg Quality and Albumen Amino Acids Composition in Aged Hens with Gut Microbiota Alternation

As it is known to all that the laying rate of commercial laying hens is significantly decreased during the late laying period, paralleled with increased feed conversion rate (FCR) and declined egg quality. However, recent studies demonstrate that reproductive performance as well as egg quality in aged hens can be largely improved by feed supplements. Among them, glycerol monolaurate (GML), a monoglyceride of medium chain fatty acids, is regarded as a promising supplement in poultry production. The aim of this experiment was to evaluate the effect of dietary GML on laying performance, serum biochemical indices, egg quality and gut microbiota in hens during 40–64 weeks of age. A total of 378 (40-week-old) Hy-Line Brown laying hens were randomly assigned into three treatments (21 hens/replicate and 6 replicates/treatment). The control group received a basal diet, and the treated groups fed basal diets containing 150 and 300 mg/kg GML. The results revealed that laying rate (p &lt; 0.05) was significantly increased and the FCR (p &lt; 0.05) was reduced in GML-containing groups compared with the control group. The egg quality (including eggshell thickness and strength) was notably improved by GML supplementation at the later late laying period, and the content of total amino acids and flavor amino acids in the albumen were also increased. Inclusion of 300 mg/kg GML in diet increased the levels of laying-related sex hormones (serum follicle stimulating hormone, luteinizing hormone and estradiol, p &lt; 0.05), serum calcium and lipid (total serum cholesterol, triglycerides and low-density lipoprotein cholesterol, p &lt; 0.05). Moreover, the community and microbial function of gut microbiota were notably altered by GML supplementation. These findings revealed that dietary GML improved the reproductive performance and egg quality mainly by stimulating the sex hormones secretion, serum calcium metabolism and nutrients utilization, which provided us a new approach to simultaneously promote the egg production and improve the egg quality at aged hens.

The Attenuating Effect of the Intraovarian Bone Morphogenetic Protein 4 on Age-Related Endoplasmic Reticulum Stress in Chicken Follicular Cells.

In the poultry, only less than 5% primordial follicles in the ovary can develop into the prehierarchical follicles (PHFs) leading to progressive development, ovulation, and egg formation. This low rate of recruitment indicates a huge potential for improvement of the laying performance. A great reduction in egg production is caused by aging with extensive follicular atresia. In this study, age-related changes in the laying performance and ovarian status were compared between the peak-lay (D280) and aged (D580) chickens. Subsequently, a cross coculture of PHFs and granulosa cells (GCs) from D280 or D580 hens was adopted to reveal the mechanism of declined follicle development. Results showed that persistent endoplasmic reticulum (ER) stress in GCs of the aged hens was accompanied with intensified apoptosis. Bone morphogenetic protein 4 (BMP4) secreted by GCs of PHFs in D280 hens was capable of relieving ER stress and improving follicular dominance for selection in D580 hens. During this action, BMP4 reduced free calreticulin (CALR, an ER marker) content and attenuated cell apoptosis in PHFs of D580 hens via the PERK-CHOP-BCL2/caspase3 or CALR-Ca2+-BCL2-caspase12 pathway. Furthermore, BMP4 prevented follicular atresia by promoting production of steroid hormones to improve survival of GCs in PHFs from the aged hens. In conclusion, intensified ER stress and apoptosis occurred in GCs of PHFs in aged chickens, while BMP4 secreted by GCs was capable of improving follicular viability by alleviating ER stress to promote follicular development.

Effects of dietary vitamins supplementation level on the production performance and intestinal microbiota of aged laying hens

The objective of this study was to investigate the effects of higher vitamins supplementation level on the performance, immunity, and intestinal microbiota of old laying hens. Twelve birds were randomly chosen from 312 healthy, 65-wk-old Hy-Line Brown layers for sampling after a 7-wk acclimation period. The remaining 300 hens were randomly allocated to 1 of 4 dietary treatments for a 13-wk feeding trial: basal diet (CON), basal diet with 2-fold supplementation level of lipid-soluble vitamins (LV), 2-fold supplementation level of water-soluble vitamins (WV), or 2-fold supplementation level of both lipid-soluble and water-soluble vitamins (BV), respectively. Compared with 72-wk-old laying hens, the 85-wk-old laying hens showed declined egg quality, which implied by inferior eggshell strength and yolk color (P < 0.05). However, after 13 wks feeding trial, the birds in WV group had higher yellowness of yolk color, and LV group had increased laying rate (P < 0.05) compared with CON. Meanwhile, WV and/or BV groups showed improved GSH/GSSG levels in liver and increased secretory immunoglobulin A concentrations in jejunum compared with CON (P < 0.05). In addition, higher dietary vitamin supplementation levels significantly altered the composition of intestinal microbiota, as evidenced by increased abundance of ileal Lactobacillus, whereas reduced richness of ileal Romboutsia, Turicibacter, and cecal Faecalibacterium (P < 0.05) in WV group and increased cecal Megasphaera and Phascolarctobacterium (P < 0.05) in LV group compared with CON group. In conclusion, higher vitamin supplementation levels in the diet could improve laying performance and egg quality of aged hens, which was closely correlated with the increased abundance of beneficial microbiota in the intestine.

Use of Tea Tree Essential Oil (Melaleuca alternifolia) in Laying Hen’s Nutrition on Performance and Egg Fatty Acid Profile as a Promising Sustainable Organic Agricultural Tool

The level of production in a variety of organic production systems is often lower than in other traditional production systems. In poultry production, there is also a direct negative effect of the small scale regarding sustainable organic poultry production. Regardless of differences between organic and conventional production systems, this experiment aimed to investigate the usage of tea tree Melaleuca alternifolia (Maiden and Betche) Cheel essential oils as a natural alternative to antibiotics in hen nutrition on productive parameters, table egg quality and eggs fatty acid profile as a promising sustainable organic agricultural tool. A total of 360 Lohmann Brown hens, aged 54 weeks, divided into three different treatment diets, were supplemented with 0 (T1), 40 (T2) and 80 mg/kg (T3) of M. alternifolia essential oil, respectively. Experimental treatments were replicated four times within 30 birds each. The experiment lasted for a total of 56 days (55 to 62 weeks of hens age). A 56-day experimental had two timetable periods of 28 days each: period 1 (55 to 58 weeks of hen age) and period 2 (59 to 62 weeks of hen age). For compound feed supplemented with M. alternifolia essential oil, daily egg production and the efficiency of nutrient utilization (FCR) was improved significantly (p &lt; 0.05) until the end of week 58, with a significant (p &lt; 0.05) increase in the thickness of eggshell, as well as egg production (p &lt; 0.05). However, egg mass, feed consumption, FCR and albumen height, Haugh unit, and eggshell strength did not show any significant (p &gt; 0.05) differences influenced by essential oil feed supplementation. Lower concentrations of saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA), and higher concentrations of polyunsaturated fatty acid (PUFA), were recorded with M. alternifolia essential oil supplementation, but without significant (p &gt; 0.05) differences. At the end of the experiment, the obtained results showed that the addition of M. alternifolia essential oil to hen nutrition had a positive effect on production parameters and eggs fatty acid profile, with increased eggshell thickness (p &lt; 0.05).

The effect of breed and age on the gloss of chicken eggshells

The monitoring of eggshell quality is important mainly in terms of production economy. Eggshell appearance is one of the most characteristics, influencing the purchasing behavior of consumers. Besides numerous eggshell appearance quality (color, shape, etc.), gloss is an important trait to reflect the eggshell appearance. In this study, 2 experiments were conducted to investigate the effect of breed and age on the gloss of eggshells. In experiment 1, we compared the eggshell gloss of 7 chicken breeds. In experiment 2, 105 Wanan (WA) chickens were raised, and 1 egg was collected from each individual at 26, 32, 40, and 50 wks of age. Eggshell gloss, color (L*, a*, b*), cuticle coverage (ΔE*ab), and thickness were measured. The results of experiment 1 showed that the average gloss values were highly variable among different breeds, and the highest was found in WA (gloss unit [GU] = 8.12), almost 2.5 folds as many as the lowest in Rhode Island Red (GU = 3.23). Also, the eggshell gloss of the local chicken breeds was significantly higher than the highly selected lines of egg-type chicken breeds (P < 0.001). In experiment 2, the results showed that gloss ranged from 9.08 GU to 12.12 GU with a variation of 28.38 to 39.71%. It fluctuated with the increasing age of hens and had the peak value at 26 wk. But, the correlation analysis between eggshell gloss and other eggshell quality traits were very low (−0.07 to 0.25). This study laid a foundation for improving the uniformity and intensity of eggshell gloss for breeders.

Accuracy of genomic prediction of shell quality in a White Leghorn line

Several genomic methods were applied for predicting shell quality traits recorded at 4 different hen ages in a White Leghorn line. The accuracies of genomic prediction of single-step GBLUP and single-trait Bayes B were compared with predictions of breeding values based on pedigree-BLUP under single-trait or multitrait models. Breaking strength (BS) and dynamic stiffness (Kdyn) measurements were collected on 18,524 birds from 3 consecutive generations, of which 4,164 animals also had genotypes from an Affymetrix 50K panel containing 49,591 SNPs after quality control edits. All traits had low to moderate heritability, ranging from 0.17 for BS to 0.34 for Kdyn. The highest accuracies of prediction were obtained for the multitrait single-step model. The use of marker information resulted in higher prediction accuracies than pedigree-based models for almost all traits. A genome-wide association study based on a Bayes B model was conducted to detect regions explaining the largest proportion of genetic variance. Across all 8 shell quality traits analyzed, 7 regions each explaining over 2% of genetic variance and 54 regions each explaining over 1% of genetic variance were identified. The windows explaining a large proportion of genetic variance overlapped with several potential candidate genes with biological functions linked to shell formation. A multitrait repeatability model using a single-step method is recommended for genomic evaluation of shell quality in layer chickens.

Quality of Eggs and Albumen Technological Properties as Affected by Hermetia Illucens Larvae Meal in Hens' Diet and Hen Age.

Simple SummaryConcurrently with the actual challenges in the poultry industry, we aimed to assess the changes induced by the inclusion of an alternative protein source (partially defatted Hermetia illucens larva meal, HI) at two different levels as well as hen age on the overall egg quality and deepened their effect of albumen technological properties. This study could provide useful information for the egg supply chain in order to optimize egg utilization, as a whole or as egg products, thus preventing food losses or undesirable wastes. Specifically, based on the obtained results, the eggs laid by hens fed the highest inclusion of HI would be directed towards egg product industry due to their reduced eggshell percentage and thickness which could increase their fragility. Contrariwise, due to the impaired albumen technological properties, as foaming, found in the egg laid by 27–35 wk-old hens, they could be preferentially sold as a whole.The impact on the egg quality and the albumen technological properties were here evaluated as affected by diet and hen age (A) of 162 Hy-line Brown hens. Three isoproteic and isoenergetic diets were formulated respecting the requirements for Hy-line hens: the control diet (C) based on conventional protein sources, and other two where vegetable proteins were substituted at 25% (HI25) and 50% (HI50) by partially defatted Hermetia illucens larva meal (HI). Ten eggs collected from each group at the hen ages of 20, 27, and 35 weeks were evaluated. The eggshell percentage and thickness were significantly reduced in the HI50 eggs (11.93% and 476 µm, respectively) compared to the C (12.34%, 542 µm) and HI25 (12.54%, 516 µm). The aging lowered (p = 0.05) the protein and increased (p < 0.001) water contents of the eggs. Although the foam capacity of the HI50 albumen was halved than the C group (p < 0.05), it was unaffected by the aging. Additionally, this did not impair the volume and the textural properties of a batter (angel cake) in which it was included. On the opposite, the textural characteristics of the cake made by the oldest hens (i.e., 35 wk-old) were compromised. In conclusion, the diet and hen age differently affected egg quality and its technological properties, which could be positive to obtain eggs to destine directly to the market or to the egg industry.

Effect of Magnetic Water on Semen Evaluation and Some Hatchability Traits for Egyptian Developed Chickens

A total of 280 females with 28 males for Silver Sabahia strain at two different ages (35 and 50 weeks) were used in this study. Besides, 40 cocks (10 cocks / group) used for semen evaluation. Birds of each age were divided into two groups, the 1st group drank water exposed to magnetic field (MFW) and the 2nd group drank non-magnetic tap water (TW) to determine the beneficial effect of drinking magnetized water for aged chickens to cope low fertility% and hatchability%, besides studying semen and egg parameters, embryonic development and chick quality. Supplementation elder cocks with MFW significantly increased semen volume, number of motile sperm and number of live sperm compared with those for untreated cocks. Treated old flock with magnetic water had a heavier egg weight (p≤0.05) than treated young flock with magnetic water. MFW X old and MFW X young had a comparable influence on egg weight loss, embryonic mortality, fertility% and hatchability%. On day 14 and 18 of incubation, supplementation older birds with MFW water had a heavier residual yolk sac weight% compared with the other rest groups. At hatch, the residual yolk sac weight% was similar between MFW X old and MFW X young. In addition, chick weight and all internal organs weight% were not affected by interaction of both types of water and hens age. It is concluded that exposing water to magnetic field, have a stimulating influence on the percentages of fertility and hatchability of birds (especially older age) through improving semen and egg qualities, besides stimulating the development of embryogenesis.

Quality of eggs from pasture rearing layers of different genotypes

The comparison of physical quality properties of table eggs of commercial hybrid Tetra SL and two native indigenous breeds of hens, Banat Naked Neck and Svrljig hen, was performed in conditions of alternative production in the pasture system in portable cages without the floor. The experiment was conducted during the vegetation period, at the age of hens of 53-57 weeks. In order to produce good quality eggs, the diet was designed with a complete mixture based on maize and soybean. In addition, constant availability of pastures was ensured. Egg sampling was performed in the morning and the initial egg quality was examined based on egg weight, shape index, egg white, egg yolk and shell quality parameters. Layer hens of the commercial hybrid Tetra SL had significantly higher egg weight and better internal egg quality (p&lt;0.01) compared to hens of Banat Naked Neck and Svrljig hens, except for the colour of the yolk, which was more intense in the same feeding and breeding conditions and the age of laying hens, in eggs of native breeds (p&lt;0.01). Native breeds in relation to the commercial hybrid had lighter shell colour (p&lt;0.01). Deformation and egg shell thickness differed (p&lt;0.01) between all three genotypes. The determined rank of layer hen genotypes for shell thickness was: Tetra SL, Banat Naked Neck, Svrljig hen. However, the breaking force was without statistically confirmed difference between hen genotypes.

The productivity of 4th Generation KUB-2 Chicken

KUB-2 line of chicken has improved local chicken selected from the KUB-1 chicken line. KUB-2 was selected for more egg production and yellow shank. KUB-1 chicken has 64% various of black feather color, which sometimes tends to have unpreferred dark carcass. Yellow shank color has a positive correlation with the skin color of carcass. As many as 517 pullets of KUB-2 at 4th generation were divided into two groups of 194 pullets of KUB-2kk (yellow shank) and 323 pullets of KUB-2nk non-yellow shank). The chickens were raised intensively in the individual cages for the 24 weeks observation. Variables measured were age at first egg (AFE) bodyweight at first egg (BWFE), egg weight at first egg (EWFE), average egg weight (AEW), average egg production (AEP) during 24 weeks, feed conversion ratio (FCR) of 25-43 weeks of age, and mortality. The result showed that there was no statistically significant different (p&gt;0.05) between KUB-2nk and KUB-2kk respectively for AFE of 156.2 d and 158.1 d, for BWFE of 1788 g and 1808 g, for EWFE of 31.32 g and 31.34 g, for AEP24 of 103.3 eggs or 61.5% and 101.9 eggs or 60.7%, and for FCR25-43 of 3.53 and 3.54. AEW increased with increasing age of hen, the mortality of the whole population was 0.98%.

Beneficial effects of dietary coenzyme Q10 on the productive and reproductive variables of broiler breeder hens

The aim of this study was to evaluate the effects of supplementary CoQ10 in the diets of aged broiler breeder hens on productive and reproductive variables. A total of 128 hens)44 weeks of age) were randomly assigned to one of 16 groups (eight hens per group). The hen-groups (with equal mean egg production and egg weight) were randomly assigned to one of four diet-groups to provide four pen/groups per treatment. There was no CoQ10 supplementation or supplemental amounts of either 300, 600 or 900 mg CoQ10/kg added to the basal diet. Egg production, weight, and mass were determined weekly. To assess fertility, hatchability, and sperm penetration (SP) rate, the hens were artificially inseminated on a weekly basis (from 47–54 weeks of age). The hens were weighed and killed at the end of the experiment for evaluation of the ovarian morphology, oviduct histology, utero-vaginal junction (UVJ) total antioxidant capacity (TAC), and Pdss2, GDF9, and BMP15 mRNA transcript abundances in the germinal disc regions. The results indicated that there was a linear response curve to increasing amounts of supplemental dietary CoQ10 on fertility, hatchability of eggs, SP rates, TAC of the UVJ, fold height and surface epithelia of the magnum and isthmus, and abundance of GDF9, BMP15 and Pdss2 mRNA transcripts in the germinal disc region. In conclusion, the findings of the present study indicate diet supplementation with CoQ10 had beneficial effects on the productive and reproductive variables of aged hens.

PSXIII-42 Plasma levels of growth hormone in laying hens in relation to developmental and hormonal factors

Abstract Growth hormone (GH) is an important positive regulator of ovarian function in vertebrates, including birds, but it can accelerate aging processes. In the present study, GH levels in the blood of laying hens were investigated due to age, reproductive status and ovulatory cycle-related hormones. To this end, the following groups of hens were used: (1) young hens with long clutch (YLC, 29–31 week-old, &amp;gt;10 eggs per clutch), (2) YLC hens treated with LH (YLC-LH), (3) old hens with long clutch (OLC, 62–64 week-old), (4) old hens with short clutch (OSC, 3–6 eggs per clutch). The hens were sacrificed at 1.5 or 14.5 h after assumed ovulation as well as 3.5 h after the LH injection (n = 5–6 per each group). Plasma concentrations of GH were determined by RIA and those of ovarian steroid hormones were measured by ELISA. The data were analyzed by ANOVA. In all compared groups, levels of GH were similar at the beginning and the middle of the ovulatory cycle. The average concentration of GH in OSC hens was higher than in OLC hens (1.28±0.38 vs 0.39±0.09 ng/ml, P &amp;lt; 0.05) but did not differ from that in YLC hens (0.76±0.22 ng/ml). Furthermore, in OSC hens, a positive correlation (r=0.84, P &amp;lt; 0.05) was revealed between GH levels and testosterone levels in the middle of the ovulatory cycle. Injections of LH raised ovarian steroid concentrations (P &amp;lt; 0.001) and did not affect GH concentrations in the plasma of YLC hens. Meanwhile, GH levels correlated with estradiol-17β levels in the YLC-LH group (r=0.81, P &amp;lt; 0.05). The findings suggest that elevated plasma levels of GH are associated with a reproductive impairment in old hens. Besides, a relationship between GH and ovarian steroids depends on the hen age, reproductive status, ovulatory cycle stage, and LH impact. The study was supported partly by RFBR (19-016-00216).

The effects of hen's age and egg storage time on the frequency of occurrence of physical defects in turkey poults

The aim of this study was to determine the effect of the interaction between hen's age and egg storage time on the frequency of occurrence and type of physical defects in turkey poults. The experimental materials comprised 6,048 eggs laid by BUT 6 turkey hens at 32, 38, 46, and 51 wk of age (1,512 eggs per week), which were randomly divided into 4 groups (378 eggs per group) and stored for different periods of time, i.e., 7, 10, 13, and 17 D. After incubation, poults were evaluated individually. Egg weight and the hatch-weight of poults increased with hen's age (P < 0.001). The relative body weight of poults, expressed as a percentage of egg weight, was highest in the group of the youngest hens (70.6%). Prolonged egg storage before incubation contributed to an increase in the percentage of poults with physical abnormalities (P < 0.001). Umbilical abnormalities were most common regardless of the week of the laying season and egg storage time.

Changes in the quality of eggs during storage depending on the housing system and the age of hens

The objective of the study was to evaluate changes during storage time (0, 7, 14, and 21 D) in the weight, albumen quality and its functional properties, and protein content of eggs from enriched cage and free range at 26 and 51 wk of age. Egg weight was affected by a significant interaction between the housing system and the age of hens. Regarding individual factors, heavier eggs (P < 0.001) were obtained with the enriched cage (61.7g) environment than with free range (59.6g) environment at 51 wk (P < 0.001) (63.3g vs. 58.0g), and freshly laid eggs were heavier compared to eggs stored for 14 and 21 D (P < 0.001). The significant interaction of evaluated factors affecting egg weight loss included the Haugh unit score and pH. Albumen dry matter content was significantly higher in free-range eggs (14.70%vs. 14.0%), in eggs from younger hens (15.0%vs. 13.7%) and in eggs that were stored 21 D. Free-range eggs contained more lysozyme (P < 0.001), and younger hens produced eggs with higher ovotransferrin (P < 0.05) and ovalbumin content (P < 0.01). The data from the study show that the evaluated factors and their interactions significantly affected the physical parameters of the eggs, whereas albumen functional properties and lysozymes, ovalbumin, and ovotransferrin were negligibly affected.

Dietary supplementation of 25-hydroxycholecalciferol improves livability in broiler breeder hens

The study aimed to examine the effects of 25-hydroxycholecalciferol (25-OH-D3) on reproductive performance and livability in broiler breeder hens. Hens at age of 26 wk were continued on restricted rations (R) or allowed ad libitum feeding (Ad) to 60 wk of age. Ad-feed intake greatly impaired egg production and hens' livability. The survival rate in both R- and Ad-hens was improved (86.7vs.78.9% and 48.2vs.29.1%, respectively) as was egg production in R-hens (P < 0.05) by inclusion of 69 μg 25-OH-D3/kg feedin the basal diet. Sudden death (SD) was the cause of hen mortality; hens died earlier with heavier BW and greater absolute and relative abdominal fat weights than surviving hens. Interestingly, feed intake of SD hens became less than that of surviving hens after 37 and 42 wk in Ad- and R-groups, respectively, and led to a progressive decline in SD hen BW with a ratio (relative to surviving hens of the same age) equaled 1 around 34 to 38 wk in Ad-groups and 52 to 53 wk in R-groups. Supplementation of 25-OH-D3 ameliorated untoward changes of heart and respiratory rate of Ad-survivors after 29 wk (P < 0.05), but had no significant effects on SD AD-hens. In contrast to the surviving counterparts, all SD hens experienced persistently higher respiratory rates in conjunction with declining heart rates (P < 0.05), suggesting compromised cardiac function as the cause of SD, in which hens increased heart and respiratory rate for more blood and oxygen supply to meet the need for rapid BW gain and/or adiposity in response to Ad-feed intake or due to genetically better feed efficiency even under R-feed intake. As the cardiorespiratory derangements advanced, compromised cardiac function ultimately led to heart failure and sudden death despite spontaneous reductions in feed intake and BW loss in all SD hens. Provision of 69 μg 25-OH-D3/kg feed is an effective and practical method to improve livability in broiler breeder hens.

Effects of the Methionine Hydroxyl Analogue Chelate Zinc on Antioxidant Capacity and Liver Metabolism Using 1H-NMR-Based Metabolomics in Aged Laying Hens.

Simple SummaryZinc, an essential trace element for laying hens, plays an important role in biological processes, such as growth, tissue growth and repairment, skeletal development, and immune competence, which also has better effects on growth performance, biochemical indexes, and antioxidant capacity. Our previous work has shown that methionine hydroxyl analogue chelated zinc (MHA-Zn) has better effects on eggshell quality, the apparent retention of minerals and nutrients, trace element deposit, and metallothionein (MT) mRNA expression. The objective of the current study was to investigate the effects of different levels of MHA-Zn on antioxidant capacity and liver metabolism of aged laying hens. The results suggest that dietary supplementation of MHA-Zn levels at 80 mg/kg has better effects on antioxidant capacity and liver metabolism, as well as homeostasis of the body. This study aimed to investigate the effects of different levels of methionine hydroxyl analogue chelated zinc (MHA-Zn) on antioxidant capacity and liver metabolism of aged laying hens. A total of 960 57-week-old layers were fed a basal diet (Zn: 35.08 mg/kg) without extra zinc for two weeks, and then allocated to four treatments consisting of eight replicates of 30 birds each for 14 weeks. Four levels of Zn (zinc sulfate (ZnSO4): 80 mg/kg; MHA-Zn: 20, 40, 80 mg/kg) were added to the diet. The results indicated that compared with inorganic zinc, organic zinc of 80 mg/kg has a significant advantage in improving the antioxidant capacity of aged hens, which increased the level of Cu/Zn-superoxide dismutase (SOD) and the total antioxidant capacity (T-AOC) in the serum and liver, and reduced the concentration of malondialdehyde (MDA) of laying hens. The serum albumen composition was significantly modified, meanwhile, the level of total protein, globulin, and urea increased remarkably, whereas serum glutamic-oxaloacetic transaminase decreased notably in 80 mg/kg MHA-Zn groups. Compared with the 20 mg/kg MHA-Zn group, the metabolic profile of 40 and 80 mg/kg MHA-Zn groups was higher than that of the inorganic zinc group. Furthermore, integrated key metabolic pathway analysis showed that 40 and 80 mg/kg MHA-Zn groups participated in the regulation of glutathione metabolism, glycine, serine, and threonine metabolism. Therefore, this study suggests that 40 and 80 mg/kg supplementation of MHA-Zn can increase the activity of Cu/Zn-SOD and T-AOC and decrease MDA; additionally the 80 mg/kg MHA-Zn group has better antioxidant capacity. Meanwhile, the enhanced MHA-Zn promoted methionine (Met) synthesis and protein metabolism.

The impact of breeder age on egg quality and lysozyme activity

The aim of this study was to analyze the biological components of eggs as well as lysozyme activity in relation to the age of hens. The research material consisted of eggs from parent stock of Ross 308 meat chickens. The eggs were evaluated at peak laying, i.e. eggs from 30-week-old hens, and after peak laying, i.e. from hens aged 60 weeks. Ninety eggs were evaluated in each period (180 eggs in total). Egg quality traits were divided into destructive and nondestructive traits. In addition, lysozyme activity in the albumen of the eggs was assessed. The quantitative characteristics of the eggs were found to increase with the age of the hens, with a smaller proportion of albumen and a larger of yolk. Egg weight, egg shape index, albumen and yolk weight, and air cell depth were increased with the hen?s age. The eggshell qualitative traits were changed with the hen?s age. Analyses showed that the shell weight and color of shells increased with the decrease of the density and strength of this element. In eggs from older hens marbled shells and pimples were found significantly more frequently. The lysozyme activity in the egg albumen also changed with the age of the hens. The activity of this enzyme was higher in the eggs of older hens.