Young Hens Research Articles

PSX-A-24 Late-Breaking: Testosterone production by theca cells of large preovulatory follicles is affected by growth hormone depending on the hen age and the presence of granulosa cells

Abstract Testosterone produced by theca cells may be involved in regulating of the growth and ovulation of hen preovulatory follicles (Rangel, Gutierrez, Gen Comp Endocrinol, 203:250, 2014). In the current research, we studied effects of growth hormone (GH), a known regulator of the hen ovarian function, on in vitro testosterone production by the theca layer (TL) from the two largest yellow follicles in relation to the hen age and the presence of the granulosa layer (GL). Young hens with long clutch (YLC, 32–33 week-old, >10 eggs per clutch) and old hens with short clutch (OSC, 74–76 week-old, 3–6 eggs per clutch) were used. After isolation, TL from F1 and F2 follicles (n = 8–9) was cultured for 18 h in two systems, separately or together with the corresponding GL, in the presence or absence of chicken GH (25 ng/ml). Concentrations of testosterone in the spent media were measured by ELISA. The data were analyzed by RM-ANOVA. In the case of separate TL culture, GH did not change significantly testosterone production in both follicles of YLC hens and reduced it from 338±105 to 152±52 fmol/mg tissue (P < 0.05) in F1 follicles of OSC hens. When TL was cultured in the presence of GL, GH enhanced 1.8-2.6-fold (P < 0.05) the secretion of testosterone in the case of F1 follicles and decreased it 1.8-2.5-fold (P < 0.05) in the case of F2 follicles in both young and old hens. Regardless of the treatment, follicular size or culture system, the production of testosterone in OSC hens was 2–5 times higher than in YLC hens. The results indicate that the interaction between TL and GL changes the steroidogenic response of theca cells from preovulatory follicles to GH in young and old hens. Furthermore, testosterone production is obviously increased with reproductive aging of laying hens. The study was supported by RFBR (19-016-00216).

Heritability of perching behavior and its genetic relationship with incidence of floor eggs in Rhode Island Red chickens

BackgroundAs cage-free production systems become increasingly popular, behavioral traits such as nesting behavior and temperament have become more important. The objective of this study was to estimate heritabilities for frequency of perching and proportion of floor eggs and their genetic correlation in two Rhode Island Red lines.ResultsThe percent of hens observed perching tended to increase and the proportion of eggs laid on the floor tended to decrease as the test progressed. This suggests the ability of hens to learn to use nests and perches. Under the bivariate repeatability model, estimates of heritability in the two lines were 0.22 ± 0.04 and 0.07 ± 0.05 for the percent of hens perching, and 0.52 ± 0.05 and 0.45 ± 0.05 for the percent of floor eggs. Estimates of the genetic correlation between perching and floor eggs were − 0.26 ± 0.14 and − 0.19 ± 0.27 for the two lines, suggesting that, genetically, there was some tendency for hens that better use perches to also use nests; but the phenotypic correlation was close to zero. Random regression models indicated the presence of a genetic component for learning ability.ConclusionsIn conclusion, perching and tendency to lay floor eggs were shown to be a learned behavior, which stresses the importance of proper management and training of pullets and young hens. A significant genetic component was found, confirming the possibility to improve nesting behavior for cage-free systems through genetic selection.

Effect of feed additions marine and plant origin on growth of poultry

The article contains materials of scientific and economic experience on the use of feed flour from Japanese Corbicula and Eastern Galega in feeding young hens. We conducted two scientific research and economic experiments on the inclusion of these additives in the diet of young poultry. Experiments were carried out on young poultry of the Haysex white cross. The purpose of the research work is to study the possibility of including in the diets feed flour from Japanese Corbicula and plant additives made from Eastern Galega. Thus, when feed flour from Japanese Corbicula was included in the diet of young poultry, the following results were obtained: weight gain increased by 14.3-19%. The inclusion of plant-based additives in the diet of young poultry increased the live weight in the experimental groups by 10.5-14.9%.

Effect of Age on Bone Structure Parameters in Laying Hens.

Simple SummaryLaying hens supply calcium to their eggshells via a process of dynamic bone formation and resorption called remodeling. As hens age, their bone becomes weak and brittle due to an imbalance in remodeling, resulting in bone disorders. Osteoporosis, characterized by bone mass loss and increased risk of fractures, is a serious problem in the egg industry, affecting both productivity and animal welfare. Nonetheless, the mechanisms of age-related osteoporosis remain unknown. We evaluated differences in bone structure between age groups, using microscopy and 3D imaging. Bone quality was reduced by an increase in porosity, with loss of volume, contributing to age-related osteoporosis.Changes in medullary and cortical bone structure with age remain unclear. Twenty Hy-Line W36 hens, 25 or 52 weeks of age, were euthanized, and both tibiae were collected when an egg was present in the magnum. Serial cross sections of the tibiae were stained with Alcian blue. The bones were scanned using micro-computed tomography. Trabecular width (Tb.Wi) was significantly higher (p < 0.05) in 25-week-old hens, whereas medullary bone tissue volume (TV) was significantly higher (p < 0.01) in 52-week-old hens. 25-week-old hens had significantly higher (p < 0.01) bone volume fraction (BVF = calcified tissue / TV). Moreover, the cortical bone parameters were significantly higher (TV and bone mineral content (BMC) at p < 0.05, and bone volume (BV) and BVF at p < 0.01) in younger hens. Open porosity and total porosity, which indicate less density, were significantly higher (p < 0.01) in older hens. Older hens showed significantly higher (p < 0.01) tibial diaphysis TV than younger hens. Younger hens had significantly higher (p < 0.01) BV, BVF and bone mineral density (BMD) of the tibial diaphysis. These findings reveal that reductions in medullary bone quality might be associated with age-related low estrogen levels and stimulation of osteoclastic bone resorption by parathyroid hormone. Cortical bone quality decreased with enlargement of the Haversian canals and loss of volume, with a longer egg-laying period leading to osteoporosis.

Comparison of naturally-occurring versus experimental infection of Staphylococcus aureus septicemia in Laying Hens in two different age groups.

In April and November of 2018, multiple commercial laying hen flocks within the same company presented with a sharp increase in mortality and drop in egg production that persisted for several days. These flocks showed striking necropsy lesions consistent with systemic infection and responded to antimicrobial treatment in the feed. Staphylococcus aureus (SA) was the most frequently isolated organism from multiple tissues including comb and wattle lesions, lungs, liver, ovary, spleen, and bone marrow. Given such an uncommon presentation of SA, which is known as a secondary opportunistic pathogen, a challenge study was conducted to evaluate its role is these disease outbreaks. In the present study, laying hens of 2 ages (22 and 96 weeks) were inoculated with SA via 3 routes: oral gavage (OG), subcutaneous injection (SC), and intravenous injection (IV). Both young and old hens in the IV group showed a significant increase in body temperature and drop in body weight; however, the clinical signs observed in the naturally-occurring outbreaks were not present. SA was re-isolated at multiple time points post-challenge from all challenge groups except the negative control group. While the SC group showed localized necrosis at the injection site, microscopic changes were different from changes observed in birds from the natural outbreaks. Despite observed initial differences in route and age, the SA challenge strain was not capable of reproducing the disease on its own. The results of this study indicate that SA may have played a role in the increased mortality, clinical signs, and necropsy lesions reported with the naturally-occurring outbreaks. However, SA should still be considered as a secondary opportunistic pathogen. Other factors that could have caused the initial insult are stress, immunosuppression, or other primary infectious agents. The results of this study may aid veterinary diagnosticians, clinicians, and all poultry professionals to include SA in their differentials list as a secondary opportunistic pathogen in similar cases. This is an uncommon presentation and further field observations and clinical studies are needed to better elucidate the pathogenesis of this disease, which will in turn help to prevent future outbreaks.

Effect of age on the secretory activity of different layers of preovulatory follicles in laying hens

Age-related deterioration in female fertility is mainly associated with a decrease in the number and quality of ovarian follicles, which, in turn, leads to various endocrine disorders. In the present work, the steroidogenic activity of theca and granulosa layers from preovulatory follicles of laying hens of different ages was studied in vitro. Young hens aged 32-33 weeks with a long egg clutch and hens aged 74-76 weeks with a short egg clutch were used in the experiments. The granulosa and theca layers were isolated from the two largest preovulatory follicles F1 and F2 and cultured separately for 18 h. After culture, the concentration of sex steroid hormones in the media was determined by ELISA. The production of progesterone by the granulosa layer was 1.5-2.0 times higher in reproductively aged layers than in young layers. Concurrently, the secretory activity of granulosa cells increased with the development of follicles from the F2 stage to the F1 stage only in aged birds (from 74.0±7.5 to 97.0±10.9 pmol/mg tissue, P&lt;0.05). Furthermore, testosterone production by the theca layer in aged hens was 2.0-2.8 times higher than that in young hens, but did not change significantly with the growth of follicles in birds of both groups. At the same time the ability of theca cells to secrete estradiol-17β was 1.6-2.3 times lower (P&lt;0.001) in F1 than in F2 follicles, regardless of the age of the birds. The findings indicate that the processes associated with ovarian aging modulate the steroidogenic activity of follicular cells in laying hens, with the age-related reduction in the egg clutch being related to an increase in the basal production of progesterone and testosterone in the two largest preovulatory follicles.

Effect of laying hens age and housing system on physicochemical characteristics of eggs

Abstract In this study, the objective was to evaluate the effect of the age of Hy-line Brown hens – 44 and 60 weeks of age (26 and 42 weeks of laying) and housing system (enriched cages and litter) on the quality of eggs. According to our results, eggs with a better quality of albumen were obtained from younger hens than from older hens. Moreover, older hens produced eggs with inferior quality related to shell parameters, such as greater elastic deformation, poorer breaking strength, and thinner shells. However, hens kept in a litter housing system laid eggs with superior shell quality characteristics of less flexible and greater breaking strength, even though the thickness, weight, and percentage were similar in both housing systems. In addition, a higher amount and activity of lysozyme were obtained from eggs laid by hens kept in the litter housing system than those obtained from hens kept in cages. The maintenance system and age of birds also had a significant (P≤0.05) effect on the basic chemical composition of eggs, as well as on the proportion of individual elements and fatty acid profile. Taking these results into account, we can conclude that the more valuable characteristics from the morphological and nutritional point of view were observed in eggs obtained from younger Hy-line hens kept in the litter housing system.

Effect of chlorogenic acid on intestinal inflammation, antioxidant status, and microbial community of young hens challenged with acute heat stress.

Heat stress in poultry is deleterious to productive performance. Chlorogenic acid (CGA) exerts antibacterial, anti-inflammatory, and antioxidant properties. This study was conducted to evaluate the effects of dietary supplemental CGA on the intestinal health and cecal microbiota composition of young hens challenged with acute heat stress. 100-day-old Hy-line brown pullets were randomly divided into four groups. The control group (C) and heat stress group (HS) received a basal diet. HS + CGA300 group and HS + CGA600 group received a basal diet supplemented with 300- and 600-mg/kg CGA, respectively, for 2 weeks before heat stress exposure. Pullets of HS, HS + CGA300 , and HS + CGA600 group were exposed to 38°C for 4 h while the control group was maintained at 25°C. In this study, dietary CGA supplementation had effect on mitigate the decreased T-AOC and T-SOD activities and the increasing of IL-1β and TNFα induced by acute heat stress. Dietary supplementation with 600 mg/kg CGA had better effect on increasing the relative abundance of beneficial bacterial genera, such as Rikenellaceae RC9_gut_group, Ruminococcaceae UCG-005, and Christensenellaceae R-7_group, and deceasing bacteria genera involved in inflammation, such as Sutterella species. Therefore, CGA can ameliorate acute heat stress damage through suppressing inflammation and improved antioxidant capacity and cecal microbiota composition.

Transcriptome analysis and identification of age-associated fertility decreased genes in hen uterovaginal junction

Avian sperm storage tubules (SSTs), which are located in the uterovaginal junction (UVJ) of the oviduct, are primary sperm storage sites after mating or artificial insemination. The mechanism underlying reduced sperm storage efficiency of SSTs which is highly correlated with decreased fertility rates in aged laying breeders remains largely unclear. Here, comparative transcriptomic analysis between the aged and young White Leghorn hens (120 vs. 30 wk) was applied to identify gene expression changes of UVJs containing SSTs. Bioinformatics analysis revealed 567 upregulated and 1998 downregulated differentially expressed genes. Gene ontology analysis was highly enriched in terms of immune system, cell adhesion, and cytoskeleton proteins. Kyoto Encyclopedia of Genes and Genomes analysis revealed 5 significant (P < 0.05) pathways including inositol phosphate and glycerophospholipid metabolism. β-Galactosidase staining of chicken UVJ sections suggested increased cell senescence via aging. Oil Red O staining and immunohistochemistry detection of ADFP both confirmed distribution of lipid droplets in SST cells with increased intensity in aged breeders. The lipid synthesis and metabolism-related genes represented by TFAP2 and PLD1 were differentially expressed in aged laying breeders. The upregulation of IL15 and downregulation of a large number of immune-related genes in aged breeders indicate altered immune homeostasis in UVJs and SSTs. The increased accumulation of lipids, and altered immunity homeostasis, combined with other factors (TJP1, MYL9, AFDN, and RPL13, etc.) are potentially dominant effectors to decrease the sperm storage efficiency and egg fertility in aged laying breeders.

PSII-32 In vitro effect of growth hormone on progesterone production by large preovulatory follicles depends on the hen age and follicular layers interaction

Abstract Growth hormone (GH) is an endocrine and paracrine/autocrine regulator of the hen ovarian function, with the GH receptor concentration in the granulosa layer (GL) being maximum in the largest preovulatory follicle (Lebedeva et al. 2004, Biol.Reprod. 71:1174–1181). In the present study, GH effects on in vitro production of progesterone by GL from the two largest yellow follicles (F1 and F2) were investigated due to the hen age and the presence of the theca layer (TL). Young hens with long clutch (YLC, 32–33 week-old, &amp;gt;10 eggs per clutch) and old hens with short clutch (OSC, 74–76 week-old, 3–6 eggs per clutch) were used. After isolation, GL from F1 and F2 follicles (n = 8–9) was cultured separately or jointly with the respective TL for 18 h in the presence or absence of chicken GH (25 ng/ml). Concentrations of progesterone in culture media were measured by ELISA. The data were analyzed by repeated measures ANOVA. When GL from F1 follicle cultured alone, GH did not affect progesterone production in YLC hens and decreased it from 30,5±3,4 to 20,5±2,9 ng/mg tissue (P &amp;lt; 0.01) in OSC hens. Conversely, when tested GL from F2 follicle, GH increased progesterone output from 15,8±2,4 to 20,4±2,5 ng/mg tissue (P &amp;lt; 0.05) in YLC birds and had no effect on the output in OSC birds. During co-culture of GL and TL, GH raised 1.4–1.5 times the production of progesterone in the case of F1 follicle and did not change it in the case of F2 follicle in hens of both ages. The findings indicate that the steroidogenic response of GL from the two largest preovulatory follicles to GH differs in young and old hens. However, the interaction with TL modifies the GL response and makes it similar in birds regardless the age and reproductive status. The study was supported by RFBR (19-016-00216).

Uterine transcriptome analysis reveals mRNA expression changes associated with the ultrastructure differences of eggshell in young and aged laying hens

BackgroundLower eggshell quality in the late laying period leads to economic loss. It is a major threat to the quality and safety of egg products. Age-related variations in ultrastructure were thought to induce this deterioration. Eggshell formation is a highly complex process under precise regulation of genes and biological pathways in uterus of laying hens. Herein, we evaluated the physical, mechanical and ultrastructure properties of eggshell and conducted RNA sequencing to learn the transcriptomic differences in uterus between laying hens in the peak (young hens) and late phase (aged hens) of production.ResultsThe declined breaking strength and fracture toughness of eggshell were observed in aged hen group compared to those in young hen group, accompanied with ultrastructure variations including the increased thickness of mammillary layer and the decreased incidence of early fusion. During the initial stage of eggshell formation, a total of 183 differentially expressed genes (DEGs; 125 upregulated and 58 downregulated) were identified in uterus of laying hens in the late phase in relative to those at peak production. The DEGs annotated to Gene Ontology terms related to antigen processing and presentation were downregulated in aged hens compared to young hens. The contents of proinflammatory cytokine IL-1β in uterus were higher in aged hens relative to those in young hens. Besides, the genes of some matrix proteins potentially involved in eggshell mineralization, such as ovalbumin, versican and glypican 3, were also differentially expressed between two groups.ConclusionsAltered gene expression of matrix proteins along with the compromised immune function in uterus of laying hens in the late phase of production may conduce to age-related impairments of eggshell ultrastructure and mechanical properties. The current study enhances our understanding of the age-related deteriorations in eggshell ultrastructure and provides potential targets for improvement of eggshell quality in the late laying period.

The evaluation of feeding, mortality and oviposition of poultry red mite ( Dermanyssus gallinae) on aging hens using a high welfare on-hen feeding device.

A study was performed to examine any effect of hen age on the feeding ability and mortality of different life-stages of Dermanyssus gallinae [Poultry Red Mite (PRM)] when fed using a high welfare, on-hen mite feeding device. Mite feeding assays were carried out every two weeks on a cohort of five Lohman Brown hens with devices containing adult and deutonymph PRM or adult and protonymph PRM. Feeding rates and mortality of each PRM life stage and oviposition of adult female PRM were evaluated over an 18-week period. There was a significant reduction in oviposition rates of female PRM as they fed on hens of increasing age. However, no clear trend was detected between the feeding rates of all three haematophagous life stages and hen age. The same conclusion was reached regarding mite mortality post-feeding in both deutonymph and adult female PRMs, although a weak positive association was apparent between hen age and protonymph PRM mortality. This study shows that the on-hen feeding device can be used both for short term studies to assess novel anti-PRM products (new acaricides, vaccines etc.) and longer, longitudinal studies to determine longevity of the effects of such novel anti-PRM products. It also demonstrates that blood feeding by mites on older hens is less able to sustain PRM populations than feeding on younger hens. This on-hen mite feeding device directly impacts upon reduction and refinement by greatly reducing the numbers of birds required per experimental group compared to traditional PRM challenge infestation models and by eliminating the need for birds to be exposed to large numbers of mites for extended periods of time that can cause welfare concerns. This paper describes the methodology for these studies and how to assemble pouches and handle mites both before and after feeding assays.

Age-related changes in egg yolk composition between conventional and organic table eggs

The aim of this study was to investigate fatty acids, fat-soluble vitamins, malondialdehyde and cholesterol in conventional and organic eggs obtained from hens of different ages (30 and 60 weeks). A total of 360 egg yolks were used in this study. Polyunsaturated fatty acid, omega-3, and omega-6 levels were higher in the organic eggs from the 30-week-old hens. The monounsaturated fatty acid level was higher in the conventional eggs but was the same between the two age groups. Cholesterol and vitamin A levels were not influenced by either the rearing system or the age of the hens. The malondialdehyde, vitamin D2, and vitamin K2 were higher in the organic eggs; however, vitamin E was higher in the conventional eggs. The results showed that the rearing system and age, as well as the diet, had an impact on the composition of the egg. Total levels of polyunsaturated fatty acid, omega-3, and omega-6 are higher in organic eggs produced by younger hens.

The use of poly additive Nabicat in the feeding of laying hens

In modern poultry farming the most urgent tasks are to search for and test new environmentally safe feed and economically justifi ed additives that stimulate productivity, positively aff ect the health of poultry, and consequently increase the livability of livestock and other important zootechnical traits. In order to maintain physiologically normal processes of life, metabolism and increase the level of productivity of poultry it needs mineral components and their chelated compounds. The purpose of this work was to increase the egg productivity of poultry by using the silicon-containing poly additive Nabicat in feeding young hens and laying hens. The researches have been carried out on the poultry cross Highsex Brown under the environments in CJSC “Poultry Farm “Volzhskaya” in the Sredneakhtubinsky area in the Volgograd region. In this paper, The optimal dose of the introduction of the silicon-containing poly additive Nabicat in the diets of young and laying hens of the cross Highsex Brown has been scientifi cally justifi ed and the biological value of using an organic form of silicon has been determined. The positive infl uence of the optimal dose of poly additive on growth, consumption, and digestibility, nutrient metabolism in the poultry body, as well as egg productivity and quality of the resulting egg has been revealed. Thus, the average egg productivity per 1 hen in the control group during the experiment period was 321,3 pcs., and in the 1st, 2nd and 3rd experimental groups it was 322,6 pcs., 325,8 and 325,7 pcs., which was higher than in the control group by 0,40 %, 1,40 and 1,37 %, respectively. The average egg weight in the 1st experimental group exceeded the control by 0,43 g or 0,68 %, in the 2nd experimental group by 1,16 g or 1,84 %, in the 3rd experimental group by 0,81 g or 1,28 %. The economic eff ectiveness of using the organic silicon additive in the composition of Nabicat poly additive in the feeding of laying hens has been proved. The economic eff ect due to the use of diff erent doses of the introduction of silicon-containing poly additive Nabicat in compound feed for laying hens of the 1st experimental group was 141,66 rubles, the 2nd experimental group 962,76 rubles, and the 3rd experimental group 821,89 rubles.

Функциональная характеристика печени ремонтного молодняка яичных кур, выращенных при монохроматическом и белом освещении

Abstract. The aim of the research is to identify the effect of monochromatic and white lighting on the functional state of the liver of egg chickens during the growing period, taking into account the season of the year. Method of research. Laboratory diagnostics of blood of 30-, 60- and 90-day old young animals. Anatomical examination of the liver of a bird at the age of 15 weeks (70 carcasses of birds were used), using the decapitation method, histological examination of the liver (19 organs), using a light microscope Carl Zeiss. Results. In all seasons of the year, the number of hemoglobin in the blood increases by 14.6 %, red blood cells by 9.4 %, albumins by 15.8 %, high values of white blood cells decrease by 2.5 times, gamma globulins by 19.8 %, bilirubin by 37.3 %, triglycerides by 26.9 %, cholesterol by 34.6 %, and asparagine aminotransferase activity by 27.5 % and alanine at 37.7 %. In young hens under white light, the amount of epicardial fat is less by 13.0–78.1 %, abdominal fat by 30.5–64.9 %, than in birds with monochromatic lamps. Histological examination of the liver of hens containing in any light revealed chronic hepatitis. In birds by white and yellow lighting, the development of the inflammatory process is less pronounced, there is no significant increase in the size of the nucleus and cells of hepatocytes, the expansion of the lumen of blood vessels, the number of lymphoid follicles in the centre and intermediate zone of the liver lobes less is 36.2–55.7 %, than in young hens by green and blue (white-blue) lighting. Scientific novelty. The use of white and yellow compact fluorescent lamps with a color temperature of 4500–5500 K and 2800–3000 K, respectively, with a light flux of 400–800 LM in the poultry house, has a weak positive effect on the functional state of the liver of egg chickens during the the period of growing from the daily age to the age of 15 weeks in cells in conditions of gradually decreasing length of daylight hours and light level.

The Effect of Bacterial Enzyme-Based Feed Additives on the Productivity, Digestibility and Assimilation of Nutrients in Young Laying Hens

The work aimed to study the effect of feed additives based on proteinase and phytase on the productivity, digestibility of nutrients and the development of laying hens up to 18 weeks of age. A total of 360 1-day-old Hisex Brown chickens were assigned to a completely randomized design composed of 3 diets with 4 replicates of 30 birds each. Dietary treatments were: (1) Control group: Basic diet with nutritional parameters consistent with recommended feeding standards, without enzymes additives, (2) experimental group A: Basic diet with the addition of proteinase at a concentration of 10 U/kg, (3) experimental group B: Basic diet with the addition of phytase at a concentration of 1000 FTU/kg. It has been shown that by adding microbial enzyme is increased digestibility of organic matter of diet of laying hens (p

ВЛИЯНИЕ БЕТА - ГЛЮКАНА НА ОРГАНИЗМ БРОЙЛЕРОВ

Our studies are devoted to the search for new drugs with antioxidant, antihypoxant, immunomodulatory effects in order to in-crease the productivity of poultry. Due to the fact that beta-glucan has not previously been studied on poultry, before determining the effective therapeutic range of its doses, it is necessary to study the effect of a conditionally therapeutic dose of the drug on the body. A conditionally therapeu-tic dose - hereinafter - means the average therapeutic dose of a drug offered by the manufacturers of the respective drugs, calcu-lated for humans (mammals).The main pur-pose is to study the effect of beta-glucan on meat productivity, morphological, biochemi-cal indices of blood. In the experiment we used clinically healthy young hens of meat breeds of three months of age of the “Cobb 500” cross. The broilers of the first group (n = 9) were not prescribed the drug, they served as controls; the second group (n = 9) were given beta-glucan at 10 mg/kg body weight, corresponding to 125 g/t of food, for 14 days. The use of beta-glucan was accom-panied by an increase in the average daily body weight, gain by 4,9%, slaughter yield by 1,5%, a significant increase in blood erythrocyte content by 32,6% on day 7, monocyte level by half, a decrease in total bilirubin by 21,0%, and a decrease in blood malonic dialdehyde by 10,8% on day 14. Cumulatively all data collected indicates positive effect of beta-glucan on meat productivity, morphological composition of blood broilers and metabolism in organism and prospects of its use in poultry industry.

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).

Age-related modulation of the isthmic and uterine mucosal innate immune defense system in laying hens

Sustained production of good quality eggs for longer production cycles is a challenge for poultry farms. The impact of aging on the mucosal immune defense in the isthmus and uterus of hens, where the eggshell membrane and eggshell are formed, remains obscure. Thus, the aim of this study was to determine whether aging affects the mucosal tight junction (TJ) proteins, the synthesis of antimicrobial peptides including avian β-defensins (AvBDs) and cathelicidins (CATHs), and Toll-like receptors (TLRs) in the isthmus and uterus of laying hens. Young and aged White Leghorn laying hens (35 and 130 wk old, respectively) were used. Total RNA and protein contents were isolated from the isthmic and uterine mucosae of these hens to examine the expression of TJ proteins, AvBD, and CATH genes and AvBD proteins by the real-time polymerase chain reaction and western blotting. The results showed that the mRNA expression of TJ proteins, namely zonula occludin 2 in the isthmus and occludin in the uterus, was higher in aged hens than in young hens. Expression of 2 AvBD genes in the isthmus and 4 AvBD genes in the uterus was higher in aged hens than in young hens. However, the expression of AvBD proteins 1 and 11 was not altered by aging. Expressions of CATH genes were not affected by aging in the isthmus or uterus. Expression of TLR genes was higher in aged hens than in young hens in the isthmus, while their expression in the uterus was not affected by aging. It can be concluded that aged hens have a higher potential ability to express TJ proteins and AvBDs for mucosal defense in the isthmic and uterine mucosae than in young hens.

Effect of Hens Age and Storage Time on Functional and Physiochemical Properties of Eggs

SUMMARY In this study, we aimed to determine the effect of hens age and storage time on the functional and physicochemical properties of eggs. Eggs from hens 25–26, 45–46, 55–56, and 69–70 wk of age were assessed, when fresh (0 d) and after storage 3, 6, and 9 d at 30°C and at 50% humidity. As hens age and storage time progressed, albumen height, Haugh unit (HU) score, yolk index (YI), and vitelline membrane strength (force breaking and elasticity) significantly decreased. The values of albumen height, HU, and YI were found to be higher in eggs obtained from the younger hens (25–26 wk of age) than those from the older hens. A significant effect of hens age was also found on the yolk pH and water activity. There was no statistical difference observed between the analyzed parameters of eggs from older hens (45–70 wk of age). There was no effect of hens age on the egg quality that was found to be the best when fresh. Interaction between hens age and the storage time also had significant impact on egg weight, albumen height, HU, yolk pH and YI, yolk weight, yolk ratio, and water activity. HU and YI scores were found to be greatly influenced by the age of hens and storage time of eggs. Changes of egg quality from the younger and older hens during storage have proceeded similarly, but eggs from older hens had significantly higher eggs weight and yolk weight that changed slowly.