Control Hens Research Articles

Tissue oxidative stress and expression of chicken UCP and ANT mRNA in laying hens exposed to acute cold stress

ABSTRACT 1. Exposure to stress alters normal homoeostasis and, hence, the antioxidant defence system. The aim of this study was to examine the effect of acute cold temperature on the antioxidant defence system in hens. 2. Hy-line grey commercial layers (80 40-week-old) were randomly assigned to one of eight groups. In groups 1 to 5, hens were exposed to low temperature at −8.68°C (cool stressed) for 2, 4, 6, 8 and 10 h, respectively. In groups 6 and 7, post 10 h cool stressed, hens were quickly transferred to room at 21°C to recovery for 2 h and 4h, respectively. In treatment groups 6 and 7, post 10 h cool stressed, hens were quickly transferred to room at 21°C for 2 h and 4 h, respectively. Group 8 was the control, where hens were housed under regular condition at 21°C as controls. 3. Antioxidant enzymes (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA), in skeletal muscle, the kidney, liver and pancreas were measured. The transcription of avUCP and ANT mRNA was tested by RT-PCR. 4. The T-AOC activity was increased in the skeletal muscle of hens cold stressed for 2, 4, 6, 8 and 10 h and the 2 h recovery groups compared with control hens (p < 0.05). The GPx activity was increased in the liver and skeletal muscle after cold stress 4 h and in the pancreas of cold stress 2 h compared with the control group (p < 0.05). Antioxidant SOD activity was increased in the kidney after cold stress 6 h and in the liver after cold stress 10 h compared to the control group (p < 0.05). Measured MDA activity was increased in the pancreas after 2 h cold stress (p < 0.05). 5. UCP mRNA expression level was increased in the pectoral muscle for 2 h and 4 h recovery groups compared with the control hens (p < 0.05) and avian uncoupling protein (UPC), adenine nucleotide translocator (ANT) expression level was increased in the leg muscle of hens cold stress for 2, 6, 8 h and recovery 2 and 4 h. 6. The observed changes in the antioxidant defence system were tissue specific. Increments in levels of ANT (leg muscle) and UCP (pectoral and leg muscle) mRNA expression may be involved in the regulation of thermogenesis in skeletal muscle.

Physiological changes in the regulation of calcium and phosphorus utilization that occur after the onset of egg production in commercial laying hens.

At the onset of egg production, physiological changes governing calcium and phosphorus utilization must occur to meet demands for medullary bone formation and eggshell mineralization. The objective of this study was to identify these changes and determine if they are influenced by dietary supplementation with 1α-hydroxycholecalciferol (AlphaD3™, Iluma Alliance). Commercial laying hens fed either a control or AlphaD3-supplemented diet beginning at 18 weeks of age were sampled at 18 (n = 8) and 31 weeks (n = 8/diet) to evaluate mRNA expression associated with calcium and phosphorus utilization in kidney, shell gland, ileum, and liver, circulating vitamin D3 metabolites, and bone quality parameters in humerus, tibia, and keel bone. Though diet did not heavily influence gene expression at 31 weeks, several significant differences were observed between 18- and 31-week-old hens. Heightened sensitivity to hormones regulating calcium and phosphorus homeostasis was observed at 31 weeks, indicated by increased parathyroid hormone receptor 1, calcium-sensing receptor, calcitonin receptor, and fibroblast growth factor 23 receptors in several tissues. Increased renal expression of 25-hydroxylase and vitamin D binding protein ( DBP ) at 31 weeks suggests kidney participates in local vitamin D3 25-hydroxylation and DBP synthesis after egg production begins. Biologically active 1,25(OH)2D3 was higher at 31 weeks, with correspondingly lower inactive 24,25(OH)2D3. Increased expression of plasma membrane calcium ATPase 1 and calbindin in kidney, shell gland, and ileum suggests these are key facilitators of calcium uptake. Elevated renal inorganic phosphorus transporter 1 and 2 and sodium-dependent phosphate transporter IIa at 31 weeks suggests increased phosphorus excretion following hyperphosphatemia due to bone breakdown for eggshell formation. Diet did influence bone quality parameters. Bone mineral density in both humerus and tibia was higher in AlphaD3-supplemented hens at 31 weeks. Tibial bone mineral content increased between 18 and 31 weeks, with AlphaD3-supplemented hens increasing more than control hens. Moreover, control hens exhibited diminished tibial breaking strength at 31 weeks compared to hens at 18 weeks, while AlphaD3-supplemented hens did not. Together, these results indicate supplementation with AlphaD3 enhanced bone mineralization during the medullary bone formation period and elucidate the adaptive pathways regulating calcium and phosphorus utilization after the onset of lay.

Social Environment Alters the Duration of Rapid Yolk Deposition in Eggs of Domestic Hens.

AbstractThe social environment can drive female birds to alter their investment in reproduction in the form of greater incubation behavior, more parental care, and greater allocation of physiological mediators to yolks. However, less is known about how social variables impact the speed at which females grow ovarian follicles in preparation for ovulation. We hypothesized that the social environment would influence how long ovarian follicles remain in rapid yolk deposition before reaching the size necessary for ovulation. For 8 d, we tested the effects of three types of social interactions: no social engagement (control), engagement with the same four females (social group 1), or engagement with the same four females plus six randomly selected roosters (social group 2). Starting on day 5 of engagement, we collected eggs and measured egg and yolk masses and yolk diameters. Then we stained the yolks with potassium dichromate to quantify the number of days the ovarian follicle spent accumulating yolk. We compared the results of the treatment groups with those of the control hens that were kept in individual laying cages throughout the study. The number of eggs laid, the yolk mass, and the yolk diameter did not differ among any of the three groups, but hens exposed to both females and males produced yolks with significantly more rings than hens in the other groups. Thus, the presence of males appeared to lengthen the time it took for ovarian follicles to reach the size needed for ovulation but did not result in larger or heavier yolks.

Effect of different levels of single cell protein and probiotic microorganisms on performance, immunological responses, and intestinal histology in laying hens

AbstractAn experiment was conducted to evaluate the effects of single‐cell protein (SCP), as a valuable by‐product and substitute for soybean meal, and multistrain probiotics on the performance, blood biochemistry, intestinal histomorphology, ileal microbiota, and immune responses in laying hens. Leghorn laying hens were randomly assigned to nine experimental treatments with eight replicates of five birds each. Dietary treatments consisted of three levels of replacement of soybean meal with SCP (0.0%, 30%, and 60%) and three levels of probiotics (0.0, 50, 100 mg/kg) offered through 70 days of main recording. The result indicated that replacing 30% soybean meal with SCP in the diet significantly increased the eggshell weight, thickness, and strength; however, hens receiving 60% SCP replacement showed lower productive performance. During the second 35‐d trial, hens receiving at least 50 mg/kg probiotics produced higher eggshell weight, thickness, and strength than the control hens. Remarkable lower levels of serum cholesterol content were observed in the SCP and probiotic‐supplemented diets. The significant reduction in the ileal pH, Escherichia coli and Clostridium spp. enumerations and a remarkable increase in Lactobacillus count was observed after feeding incremental levels of probiotics. The highest villus height to crypt depth ratio, antibody titer against sheep red blood cells (in secondary response) and Newcastle disease vaccine, as well as egg production and egg mass, were found in the hens that received 30% SCP replacement in combination with 50 or 100 mg/kg probiotic (SCP × Probiotic). The present study concluded that feeding SCP, as a cheap protein alternative source, along with probiotics while reducing production costs can support productive performance via modulating the intestinal microbiomes and health indices and fortifying the immune system in laying hens.

Comparative responses of Lohmann Select Leghorn-lite and Shaver Heritage White Leghorn hens when fed diets containing fine and coarse oat hulls

A standard commercial mash (control), or a mixture of control and fine (FOH) or coarse oat hulls (COH) at a ratio of 80:20 w/ w were fed to 57-week old Lohmann Select Leghorn-lite (LSL) and 44-week old Shavers Heritage White Leghorns (SHW) for 28 days. There was no ( P &gt; 0.05) strain and diet interaction or diet effects on egg production indices (EP) and feed intake (FI). However, LSL hens had similar ( P &gt; 0.05) FI but higher ( P &gt; 0.05) EP than SHW. There was no strain and diet interaction observed on apparent retention of gross energy (ARGE) and gizzard weight ( P &gt; 0.05). However, the control hens had higher ARGE, and lighter gizzards compared to oat hull-fed hens ( P &lt; 0.01). In addition, COH hens had higher ARGE and heavier gizzards compared to FOH hens. The SHW hens exhibited greater jejunal crypt depth ( P = 0.011) compared to LSL hens. An interaction ( P = 0.041) between strain and diets on ceca digesta short chain fatty acids (SCFA) was such that oat hulls reduced SCFA in LSL but not in SHW hens. In conclusion, despite differences in age, relative to predecessors the modern hen is adaptable to ingestion of structural material rich insoluble fiber without negative impact on egg production and feed intake.

Alterations in aquaporin 4 expression in the chicken ovary following tamoxifen treatment

Previously, we demonstrated the follicular size- and a layer of the follicular wall-dependend expression of aquaporin 4 (AQP4) in the chicken ovary. In this study, we aimed to examine the mRNA and protein expression of aquaporin 4 (AQP4) in the chicken ovary during a pause in laying induced by a tamoxifen (TMX, oestrogen receptor modulator) treatment. Ovarian white and yellowish follicles and the granulosa and theca layers of the largest yellow preovulatory follicles were harvested from control and TMX-treated (daily until the cessation of egg-laying) hens. It was found that the TMX treatment lowered the AQP4 transcript abundance in the white follicles, but increased it in the theca layer of the F3-F1 follicles. Moreover, the TMX caused a decrease in AQP4 protein abundance in the theca layer of the F2 follicle. We propose that AQP4 plays a role in the ovarian follicle development and that there is a relationship between oestradiol action and the AQP4 gene and protein expression in chicken ovarian follicles.

Lactulose with synergists supplementation improving a health of chicks and reducing the environmental burden in poultry industry.

The study aims to understand the effect of new antibiotic-substituting supplements in feeding chickens of the Hisex Brown cross in industrial conditions. A total of 216 hatched chicks were randomly selected and distributed into Control, Test I, and Test II groups, with 3 replicates of 24 birds in three treatments. At the end of the experiment, BW of T1/T2 birds was higher by 6.12% (p <0.01) and 10.29% (p <0.001) than CON. In comparison with the control hens, T1/T2 birds had a higher feed conversion rate and digestibility of nutrients. The blood indicators of T1/T2 hens exceeded those in control. Prebiotic supplementations were positively influenced in the immune indices of birds. IgA, IgG, IgM increased in groups T1/T2. Similar regularity was found in the natural resistance of chicks fed S1/S2. In the caecum, the Lactobacilli number was higher than in CON by 17.03% (p <0.01) in T1 and by 18.47% (p <0.01)-in T2; Bifidobacteria-by 17.94 (p <0.001) and 19.09% (p <0.01), respectively; at the same time, the number of E. coli decreased by 21.05% (p <0.01) and 24.21% (p <0.01). The concentration of emitted excreta noxious gases decreased: ammonia by 22.40%-24.95% (p <0.01); hydrogen sulfide by 10.67%-16.00% (p <0.01); and mercaptans by 12.90%-17.74% (p <0.05). These findings support the use of lactulose-based supplements as antibiotic alternatives to improve production in poultry farming and to reduce the toxic load on the environment.

Inclusion of Dried Black Soldier Fly Larvae in Free-Range Laying Hen Diets: Effects on Production Efficiency, Feed Safety, Blood Metabolites, and Hen Health

Identifying alternative feedstuffs to replace conventional nutrient sources in poultry diets is crucial to supplying the growing demand for animal feed. A 17-week-long feeding experiment with three diets, including 0% (control), 10%, and 18% full-fat dried black soldier fly larvae (DBSFL), was conducted to evaluate the production efficiency and feed safety of using the larvae for partial (50%) and full (100%) substitutions of soybean meal and 90% replacement of soybean oil in free-range laying hen diets. Thirty hens (18–36 weeks old) were housed in two mobile poultry trailers per treatment level. The weight gain of hens, their feed intake, egg production, egg weights, feed conversion ratios, bird welfare parameters, hematology and blood metabolites, fecal microbiology, and digestive tract weights were examined. Control hens had higher weight gains, laid more and bigger eggs while consuming less feed, and had lower feed conversion ratios than 18% DBSFL hens. However, the production performances of 10% DBSFL hens were not significantly different from the control in many of the parameters considered (e.g., hen-day egg production or HDEP). In conclusion, partial replacement of soybean meal and oil with DBSFL in layer diets maintains production efficiency, feed safety, and hen health and welfare status.

Reduction in metabolic noise reveals rejuvenation following transient severe caloric restriction.

Among land vertebrates, the laying hen stands out due to its great reproductive efficiency: producing an egg daily all year long. This production rate makes the laying hen a special model animal to study the general process of reproduction and aging. One unique aspect of hens is their ability to undergo reproductive plasticity and to rejuvenate their reproductive tract during molting, a standard industrial feed restriction protocol for transiently pausing reproduction, followed by improved laying efficiency almost to peak production. Here we use longitudinal metabolomics, immunology, and physiological assays to show that molting promotes reproduction, compresses morbidity, and restores youthfulness when applied to old hens. We identified circulating metabolic biomarkers that quantitatively predict the reproduction and age of individuals. Lastly, we introduce metabolic noise, a robust, unitless, and quantifiable measure for heterogeneity of the complete metabolome as a general marker that can indicate the rate of aging of a population. Indeed, metabolic noise increased with age in control hens, whereas molted hens exhibited reduced noise following molting, indicating systemic rejuvenation. Our results suggest that metabolic noise can be used as a quick and universal proxy for assessing successful aging treatments, accelerating the timeline for drug development.

PSXIII-1 Proof of Concept of Feeding Non-Protein Nitrogen Based Special Liquid Product (StimGain) Improve the Performance and Production in Swine and Poultry

Abstract Feed is generally the greatest expense for animal production today. Improved feed formulations and new approaches of feeding existing feedstuffs are being explored to increase total protein production. The objective of this study was to determine the efficacy of an energy-based Special Liquid (StimGain) containing non-protein nitrogen (NPN), alcohol, and distiller grain solubles monogastric diets without critically affecting growth and performance. The Study 1 (Swine grow-finish test) test included 24 pigs (average purchase weight 19.1 kg) per treatment group with three replications were placed for 90 days. The treatments were: 1) Control diet with 16% protein, 2) Protein Check: Control diet with 15% protein, 3) StimGain: same as protein check including 22.7 kg of StimGain product per ton feed. The Study 2 (Laying Hen test) test included 100 pullets per treatment group, with 10 pullets per cage 10 weeks. At 10 weeks of age, pullets were placed in layer cage 2 birds per cage for 30 weeks. The treatments were: 1) Control diet, 2): Control diet + 22.7 kg StimGain product per ton feed. Each group of hens received identical amounts of minerals and vitamins. The Study 3 (Broiler Chicken test) test included 110 birds per treatment group, with 10 birds per cage for 42 days. The treatments were: 1) Control diet, 2): Control diet + 22.7 kg of StimGain product per ton feed. Each group of hens received identical amounts of minerals and Vitamins. Differences in growth performance between groups were analyzed for significance using ANOVA then used PostHoc test. Kruskal-Wallis test was done to confirm if there is a significant difference among treatments, and normality was tested by using the Wilcoxon rank sum test to do pairwise comparisons. Significance was considered at P ≤ 0.05 . The pig study (Study 1), StimGain improved average feed to gain (Control = 3.240, Protein check = 3.391, StimGain = 3.016), salable meat production (Contro l= 78.47%, Protein check = 80.02%, StimGain = 82.22%), lard formation (Control = 14.33%, Protein check = 12.39%, StimGain = 11.58%).In Study 2, StimGain increased average laying percent of hens (StimGain hens = 80.47%, Control hens = 79.34%). In the broiler chicken study (Study 3), StimGain improved Feed to Gain (StimGain = 2.590, Control = 2.911) and salable meat weight (average dressed weight to live weight percentage for StimGain birds = 69.93%, Control birds = 69.01%). Diets formulated with StimGain in pigs improved feed to gain ratio and improved the efficiency of proteins, rather than addition of protein to a conventional swine diet. Also, StimGain improved efficiency of metabolism by reducing lard formation and increasing salable meat formation in pigs. StimGain increased average laying percent of hens, and improved feed to gain and salable meat in broilers.

Effect of tamoxifen treatment on catalase (CAT) and superoxide dismutase (SOD) expression and localization in the hen oviduct

The imbalance between free reactive oxygen species (ROS) generation and removal (e.g., by antioxidative enzymes) leads to the damage of important biomolecules and cells. Earlier studies in hens showed that treatment with tamoxifen (TMX; estrogen receptor inhibitor) modulates oxidative stress and causes the reproductive system regression realized by cell apoptosis. The aim of the present study was, therefore, to examine the expression and immunolocalization of the key enzymatic antioxidants, i.e. catalase (CAT) and superoxide dismutase (SOD), in the chicken oviduct following TMX treatment. Laying hens were treated daily with TMX until a pause in egg-laying occurred and then euthanized on day 8 of the experiment. Quantitative real-time PCR and western blot analyses showed the presence of CAT and SOD transcripts and proteins, respectively, in all oviductal segments, i.e., the infundibulum, magnum, isthmus, shell gland and vagina. In control hens (laying), the mRNA expression of CAT was the highest in the shell gland, lower in the isthmus and the lowest in other oviductal parts, whereas protein expression was the highest in the magnum, lower in the isthmus and the lowest in other segments. The SOD transcript and protein abundances only were lower in the magnum than in other segments. Immunoreactive CAT and SOD products were localized in all layers of the oviductal wall, but the intensity of staining depended on the cell type. TMX treatment affected CAT and SOD expression and the effect of TMX depended on gene, protein, cell type and oviductal part. Generally, CAT expression was elevated, while SOD expression was decreased under TMX treatment. These results point to the importance of CAT and SOD in the maintenance of proper oviduct health and function. Changes in ROS scavenging enzymes after estrogen receptor blockage indicate the significance of estrogen in the regulation of oxidative status in the avian oviduct.

Increased dietary 5-hydroxytryptophan reduces fearfulness in red junglefowl hens (Gallus gallus).

Our production animals typically suffer poor welfare, which can be revealed by measuring the affective state these animals are in. Negative affective state is linked to poorer welfare, and can be measured as fearfulness. While continuing to research how to improve animal welfare, a compliment to reduce negative affective state could therefore be to reduce individuals' fearfulness, similar to how negative affective states are medicated in humans. A proposed mechanism for this is via the monoaminergic systems. This is based on previous studies across species that have linked the serotonergic system and fear-related behaviour. We here aimed to experimentally manipulate the serotonergic system in red junglefowl hens (Gallus gallus), the main ancestor of all domesticated chickens. We measured fearfulness as latency remaining immobile in a tonic immobility test, and did so both before and after our experimental manipulation. We set out to experimentally manipulate the serotonergic system via sub-chronic dietary treatment of 5-hydroxytryptophan (the precursor to serotonin). Our dietary manipulation of 5-hydroxytryptophan significantly reduced measured fearfulness in the manipulated hens, while latency in tonic immobility did not significantly change in our unmanipulated, control hens. This finding is promising since it indicates that increased tryptophan levels can be used to reduce fearfulness. Additionally, our result suggests that this can be done non-invasively via food (instead of injections), thus presenting a potentially feasible manipulation also for larger settings. Nevertheless, the serotonergic system is complex and its role in modulating behaviour in the fowl should be explored further to evaluate our findings, and more directly explored also in a production setting.

N-3 essential fatty acid and vitamin D supplementation improve skeletal health in laying hens

Keel bone fractures and osteoporosis are prevalent and damaging skeletal issues in the laying hen industry. There is a large interest in improving bone quality parameters to reduce or eliminate these conditions, thus improving bird welfare. Both essential fatty acids (EFA) and vitamin D can play a role in bone metabolism. The hypothesis of this study was that birds supplemented with lower n-6:n-3 EFA ratio or vitamin D would have improved bone properties compared to a control diet. A total of 3,520 Lohmann Brown-Lite pullets were used in this study. Pullets were housed on the floor from 0 to 17 wk of age and then moved to an aviary (17-52 wk of age). Starting at 12 wk of age, birds were split into diet treatments-control, flax, fish, or vitamin D diets with n-6:n-3 ratios of 6.750, 0.534, 0.534, and 6.750, respectively. Diets were formulated to be isonitrogenous and isocaloric. Basal vitamin D3 levels were formulated to be 2,760 IU/kg across all diets; for the vitamin D diet, the vitamin D3 level was increased to 5,520 IU/kg. Hens on fish and vitamin D diets had greater bone density, keel bone volume, digital bone mineral content, and keel condition compared to flax and control hens. Additionally, birds fed the vitamin D diet had the heaviest body weights compared to birds fed fish or control diets. Birds fed the flax and vitamin D diets had improved feather coverage across multiple body regions. Feeding an n-3 EFA- or vitamin D-enriched diet decreased mortality by 1.6 to 3.3% compared to the control. The fish and vitamin D diets generated mixed production performance. Compared to the other treatments, the vitamin D diet generated higher case weights but lower hen day percentage throughout the study. When compared to the other treatments, the fish diet had the lowest case weights but had a greater hen day percentage after 36 wk of age. Results indicate that a fish-based EFA and vitamin D supplementation show promise in improving skeletal health but require further investigation.

Unraveling the Potential of Orange Pulp for Improving Laying Rate, Egg Quality, Oxidative Stability, Fatty Acids Composition, and Reproductive Tract Morphology of Laying Hens.

The current study aimed to demonstrate the effects of dietary dried orange pulp (DOP) on the laying performance, egg quality, antioxidant status, yolk fatty acid composition, serum biochemistry, and reproductive tract morphology of laying hens. A total of 200 Lohman Brown Lite laying hens were randomly allotted into 4 dietary treatments with 10 replicates each. The experimental treatment groups were the control group, a basal diet containing 50 g DOP/kg feed (DOP5%), a basal diet containing 70 g DOP/kg feed (DOP7%), and a basal diet containing 100 g DOP/kg feed (DOP10%). Data were statistically analyzed by one-way ANOVA following a completely randomized design, and the incremental levels of dietary DOP were tested by orthogonal polynomial contrasts. The body weight gain, feed intake, egg production%, egg weight, egg mass, and feed conversion ratio of laying hens fed the DOP7% and DOP10% diets were greater (p < 0.01) than those fed the control diet. Eggs obtained from the DOP7% and DOP10% groups had a heavier shell weight% and shell thickness, as well as a greater yolk color score (p < 0.01; linear, p < 0.01). Dietary DOP improved the egg yolk concentrations of PUFA, n-3 PUFA, and n-6 PUFA (linear, p < 0.001; quadratic, p < 0.05), whereas the content of SFA was reduced (p < 0.001; linear, p < 0.001). The egg yolk cholesterol and triglyceride levels were linearly decreased (p < 0.001) with the inclusion of DOP in the diets of hens. After storage for 40 days, the malondialdehyde (MDA) contents in the egg yolk were reduced, whereas the glutathione peroxidase content was increased (p < 0.01) due to dietary DOP. The DOP7% and DOP10% hens had an obvious reduction in the levels of serum total lipids, total cholesterol, triglycerides, low-density lipoprotein, and MDA, whereas high-density lipoprotein and GPx levels were increased (p < 0.01) compared with those fed the control diet. The relative weights of the ovary, oviduct, uterus, and follicle of hens receiving diets containing 7% and 10% DOP were heavier (p < 0.01) than those of the control hens. Moreover, the number of large yellow follicles was increased (p < 0.001; linear, p < 0.001) in the hens-fed diets containing 7% and 10% DOP. In conclusion, dietary DOP at up to 100 g/kg of feed improves laying performance, health status, antioxidant capacity, egg nutritive value, and egg shelf life in laying hens.

Response of the hen ovary to eCG treatment: Insight into morphology and expression of genes related to steroidogenesis and vitellogenesis

The present study aimed to examine the effect of equine chorionic gonadotropin (eCG) treatment on the chicken ovarian folliculogenesis and steroidogenesis. The expression of vitellogenesis-related genes in the liver was also investigated. Laying hens were injected with 75 I.U./kg of body weight/0.2 mL of eCG, once a day for 7 successive days. On day 7 of the experiment hens, including control hens which were receiving vehicle, were euthanized. The liver and ovarian follicles were harvested. Blood was collected daily through the whole experiment. The eCG treatment resulted in the cessation of egg laying after 3 or 4 days. The eCG-treated hens had heavier ovaries with a higher number of yellowish and yellow follicles arranged in a non-hierarchical way in contrast to ovaries of control hens. Moreover, these birds had elevated plasma estradiol (E2) and testosterone (T) concentrations. The molar ratios of E2:progesterone (P4) and T:P4 were increased in chickens injected with eCG. Real-time polymerase chain reaction revealed changes in mRNA abundances of steroidogenesis-associated genes (StAR, CYP11A1, HSD3β, and CYP19A1) in ovarian follicles: white, yellowish, small yellow, and the largest yellow preovulatory (F3-F1) as well as VTG2, apoVLDL II, and gonadotropin receptors in the liver. In general, the abundances of gene transcripts were higher in eCG-treated hens than in control hens. Western blot analyses showed an elevated abundance of aromatase protein in the prehierarchical and small yellow follicles of eCG-treated hens. Unexpectedly, there was presence of both FSHR and LHCGR mRNA in the liver and the level of expression was shifted in eCG-treated hens. In summary, eCG treatment leads to disruption of the ovarian hierarchy with accompanying changes in circulating steroids and ovarian steroidogenesis.

Minimal effects of ultraviolet light supplementation on egg production, egg and bone quality, and health during early lay of laying hens.

Chicken vision is sensitive to ultraviolet (UV) light containing the UVA spectrum, while UVB plays a key role in the endogenous production of vitamin D3. However, commercially available light sources are typically deficient in the UV spectrum and thus may not adequately fulfill the lighting requirements of indoor-housed laying hens. We hypothesized that supplementary UVB light may improve egg production and egg quality, and bone health during early lay relative to UVA supplementation or standard control lighting. To investigate the effects of UV light supplementation, an experiment was conducted on 252 ISA Brown hens during 16 to 27 weeks of age. Birds were housed in eighteen pens (14 hens/pen) under three different light treatment groups each with six replications: (i) UVO: standard control lighting with LED white light, (ii) UVA: control lighting plus supplemental daylight with an avian bulb, and (iii) UVA/B: control lighting plus a supplemental full spectrum reptile bulb containing both UVA and UVB wavelengths. Hen-day egg production and egg quality, blood parameters including plasma Ca and P, and serum 25(OH)D3, and hen body weight and external health scoring were measured at different age points; while bone quality was assessed at the end of the experiment at 27 weeks. Data were analyzed in JMP® 16.0 using general linear mixed models with α level set at 0.05. Results showed that UVA and UVA/B supplemented birds reached sexual maturity (50% production) 3 and 1 day earlier, respectively, than control birds. There was a trend for UV lights to increase hen-day egg production (P=0.06). Among egg quality traits, only eggshell reflectivity and yolk index were affected by UV lights (P=0.02 and 0.01, respectively); however, most of the egg quality traits changed over age (all P<0.01). Post-hoc tests showed higher serum 25(OH)D3 in the UVA/B group relative to control hens (P<0.05); but there was no treatment effect on plasma Ca and P or on bone quality parameters (all P>0.05). A significant interaction was observed between light treatment and age for the number of comb wounds (P=0.0004), with the UV supplemented hens showing more comb wounds after 24 weeks. These results demonstrated that supplemental UVA/B light had minimal effects on egg production and egg quality, whereas, UVA/B exposure may increase vitamin D3 synthesis during the early laying period. The optimum duration of exposure and level of intensity needs to be determined to ensure these benefits.

Addition of a protected complex of biofactors and antioxidants to breeder hen diets confers transgenerational protection against Salmonella enterica serovar Enteritidis in progeny chicks

Addition of vitamins and antioxidants has been long associated with increased immunity and are commonly used in the poultry industry; however, less is known regarding their use in broiler breeder hens. The objective of this study was to determine if feeding a complex of protected biofactors and antioxidants composed of vitamins and fermentation extracts to broiler breeder hens conferred resistance against Salmonella enterica serovar Enteritidis (S. Enteritidis) in the progeny chicks. Three-day-old chicks from control- and supplement-fed hens were challenged with S. Enteritidis and necropsied 4- and 11-days postchallenge (dpc) to determine if there were differences in invasion and colonization. Serum and jejunum were evaluated for various cytokine and chemokine production. Fewer (P=0.002) chicks from supplement-fed hens had detectable S. Enteritidis in the ceca (32.6%) compared to chicks from control-fed hens (64%). By 11 dpc, significantly (P < 0.001) fewer chicks from supplement-fed hens were positive for S. Enteritidis (liver [36%]; ceca [16%]) compared to chicks from the control hens (liver [76%]; ceca [76%]). The recoverable S. Enteritidis in the cecal content was also lower (P=0.01) at 11 dpc. In additional to the differences in invasion and colonization, cytokine and chemokine production were distinct between the 2 groups of chicks. Chicks from supplement-fed hens had increased production of IL-16, IL-6, MIP-3α, and RANTES in the jejunum while IL-16 and MIP-1β were higher in the serum of chicks from the control-fed hens. By 11 dpc, production of IFN-γ was decreased in the jejunum of chicks from supplement-fed hens. Collectively, these data demonstrate adding a protected complex of biofactors and antioxidants to the diet of broiler breeder hens offers a measure of transgenerational protection to the progeny against S. Enteritidis infection and reduces colonization that is mediated, in part, by a robust and distinct cytokine and chemokine response locally at the intestine and systemically in the blood.

Exogenous testosterone administration decreases rates of ovarian follicle growth in domestic chickens

Avian egg yolks provide critical nutrients and energy reserves for a growing embryo. Once a follicle is selected into the ovulatory hierarchy, rings of yolk precursors are deposited daily until the yolk is large enough to ovulate. The composition of hen egg yolk and the mechanisms responsible for deposition in the ovarian follicle are well-studied. However, the factors that affect the rate of yolk deposition, and the number of days it takes for follicles to grow to the optimal size for ovulation, are less well-known. Social interactions appear to impact the rate of yolk deposition in many avian species and testosterone is a key hormone involved in regulating those interactions. Therefore, we hypothesized that testosterone would influence the rate of follicle growth. We tested the influences of exogenous testosterone treatment by rubbing either testosterone propionate cream (1.25 %) or a control cream to hen combs daily for 7 days to increase plasma testosterone concentrations. We then collected eggs and measured egg and yolk weight, yolk diameters, and stained and counted the number of concentric rings in each yolk. Testosterone-treated hens laid fewer eggs and grew their yolks more slowly than control hens. Testosterone also caused an increase in yolk weight but not yolk diameter. These results indicate that testosterone may play a role in the rate of yolk deposition in birds.

Efficacy of passive immunization in broiler chicks via an inactivated Escherichia coli autogenous vaccine administered to broiler breeder hens

ABSTRACT Avian pathogenic Escherichia coli (APEC) cause extra-intestinal infections called colibacillosis, which is the dominant bacterial disease in broilers. To date, given the diversity of APEC strains and the need for an acceptable level of protection in day-old chicks, no satisfactory commercial vaccine is available. As part of a French nationwide project, we selected three representative strains among several hundred APEC that cause colibacillosis disease. We first performed experiments to develop colibacillosis in vivo models, using an inoculum of 3 × 107 CFU of each E. coli strain per chick. Two APEC strains (19-381 and 19-383-M1) were found to be highly virulent for day-old chicks, whereas the third strain (19-385-M1) induced no mortality nor morbidity. We then produced an autogenous vaccine using the (Llyod, 1982; MaCQueen, 1967) 19–381 and 19-383-M1 APEC strains and a passive immunization trial was undertaken. Specific-pathogen-free Leghorn hens were vaccinated twice 2 weeks apart, the control group receiving a saline solution. The vaccinated and control hens exhibited no clinical signs, and egg production and fertility of both groups were similar. Fertile eggs were collected for 2 weeks after the second vaccination and chicks were obtained. After challenge with each APEC (19-381 and 19-383-M1), chicks appeared to be partially protected from infection with the 19-383-M1 strain, with 40% mortality compared with 80% for the non-vaccinated chicks. No protection was found when the chicks were challenged with the 19–381 strain. Now, further work is needed to consider some aspects: severity of the pathogen challenge model, persistence of the protection, number of APEC strains in the autogenous vaccine, choice of adjuvants, and heterologous protection by the vaccine made from strain 19-383-M1. RESEARCH HIGHLIGHTS Three APEC strains were characterized and selected to develop in vivo models of colibacillosis. A bivalent autogenous vaccine was produced and a passive immunization trial was carried out. Protection of chicks was demonstrated when challenged with the 19-383-M1 APEC strain (homologous challenge). Further work is needed in particular to evaluate the protection against heterologous challenge.

Validation of a novel model of ovarian carcinogenesis: Digital spatial profiling of premalignant fallopian tube lesions in the MADM mouse and the potential impact on primary prevention of epithelial ovarian cancer (124)

Validation of a novel model of ovarian carcinogenesis: Digital spatial profiling of premalignant fallopian tube lesions in the MADM mouse and the potential impact on primary prevention of epithelial ovarian cancer (124)