Changes in some blood parameters and production performance of old laying hens due to growth hormone and testosterone injection

Analysis of Transcriptomic Differences in the Ovaries of High- and Low-Laying Ducks

The egg-laying performance of Shan Ma ducks (Anas Platyrhynchos) is a crucial economic trait. Nevertheless, limited research has been conducted on the egg-laying performance of this species. We examined routine blood indicators and observed higher levels of metabolic and immune-related factors in the high-egg-production group compared with the low-egg-production group. Furthermore, we explored the ovarian transcriptome of both high- and low-egg-production groups of Shan Ma ducks using Illumina NovaSeq 6000 sequencing. A total of 1357 differentially expressed genes (DEGs) were identified, with 686 down-regulated and 671 up-regulated in the high-egg-production (HEP) ducks and low-egg-production (LEP) ducks. Several genes involved in the regulation of ovarian development, including neuropeptide Y (NPY), cell cycle protein-dependent kinase 1 (CDK1), and transcription factor 1 (E2F1), exhibited significant differential expressions at varying stages of egg production. Pathway functional analysis revealed that the DEGs were primarily associated with the steroid biosynthesis pathway, and the neuroactive ligand-receptor interaction pathway exhibited higher activity in the HEP group compared to the LEP group. This study offers valuable information about and novel insights into high egg production.

Dietary Canthaxanthin Supplementation Promotes the Laying Rate and Follicular Development of Huaixiang Hens

Canthaxanthin(CX) is a ketocarotenoid, which is widely used in poultry production as a lipophilic antioxidant. Huaixiang chickens are a local breed in China famous for their excellent meat quality; improving their laying rate via nutritional regulation has attracted extensive attention. The aim of this study was to evaluate the effects of dietary CX on the laying rate and follicular development in Huaixiang hens. A total of 180 Huaixiang hens were randomly divided into five groups with six replicates, and six chickens per replication. The control group (CON) were fed a basal diet, and the treatment group (NT) were fed a basal diet supplemented with 4, 6, 8 and 10 mg/kg CX. All chickens were 26 weeks old, living at an average environmental temperature of 25 ± 2 °C with a relative humidity of 65-75%. The results showed that supplementing the CX improved the laying rate and large white follicles (LWF) number (p < 0.05) and increased the concentration of reproductive hormones (LH, FSH, E2 and Prog) (p < 0.05), and the basal diet supplemented with 6 mg/kg CX worked best. Moreover, CX could increase the activities of antioxidant enzymes SOD and GSH-Px (p < 0.05) and reduce the content of the lipid peroxidation product MDA in Huaixiang chickens (p < 0.05); again, 6 mg/kg CX was best. In conclusion, dietary CX had positive effects on the laying rate, ovarian structure, reproductive hormone secretion, follicle development, and the antioxidant capacity of Huaixiang hens, and 6 mg/kg CX was recommended to be added to the diet of Huaixiang chickens.

Dietary cholecalciferol and 25-hydroxycholecalciferol supplementation interact to modulate reproductive performance, egg quality, serum antioxidant capacity, intestinal morphology and tibia quality of breeder geese

1. A study was conducted to evaluate the effects of dietary cholecalciferol (vitamin D3) and 25-hydroxycholecalciferol (25-OH-D3) supplementation on the reproductive performance, egg quality, eggshell ultrastructure, serum hormone level and antioxidant capacity, intestinal morphology and tibia quality of breeder geese during the laying period.2. The trial was designed as a 3 × 3 factorial arrangement with three levels (300, 400 and 500 IU/kg) of vitamin D3 supplementation and three levels (25, 50 and 75 μg/kg) of 25-OH-D3 supplementation in a 10-wk feeding trial.3. The results showed that the combined supplementation of 400 IU/kg vitamin D3 and 50 μg/kg 25-OH-D3 had a better feed conversion ratio and a higher egg laying rate than the other groups. Vitamin D3 supplementation significantly increased the rate of qualified eggs for hatching, eggshell strength and thickness, serum testosterone and progesterone levels, serum total superoxide dismutase and glutathione peroxidase activities, tibia ash content and bone mineral density (P < 0.05). Dietary 25-OH-D3 supplementation significantly increased serum glutathione peroxidase activity and duodenal villus height and villus height-to-crypt-depth ratio (P < 0.05). The geese receiving 500 IU/kg vitamin D3 and 75 µg/kg 25-OH-D3 had the highest tibia calcium and phosphorous content among all groups (P < 0.05).4. Feeding 400 IU/kg vitamin D3 plus 50 µg/kg 25-OH-D3 gave optimal effects on feed conversion ratio and egg laying rate. This combination could be a nutritional strategy for increasing the laying rate, eggshell quality, serum hormone levels and serum antioxidant function regardless of 25-OH-D3 supplementation. Supplementation of 50 μg/kg 25-OH-D3 could be a recommended dose for improving the serum antioxidant capacity and intestinal morphology regardless of vitamin D3 supplementation.

Effect of Dietary Supplemental Zinc on Laying Performance, Egg Quality, and Plasma Hormone Levels of Breeding Pigeons

This study aimed to evaluate the dietary zinc requirement of parental pigeons for better laying and reproductive performance, egg quality, sex hormones, and mineral content in eggs. A total of 160 pairs of healthy American Silver King pigeons were randomly assigned to five treatments of eight replicate cages each with four pairs of birds per cage, and fed a basal diet without zinc supplementation or the basal diet supplemented with 30, 60, 90, and 120 mg of zinc/kg (ZnSO₄·7H₂O). The experiment lasted for 45 days, including two laying cycles. Results indicated the egg production rate (P = 0.081), egg shape index (P = 0.038), egg eggshell percentage (P = 0.070), and zinc and calcium contents (P < 0.01) tended to be affected or significantly affected by zinc addition. They increased quadratically with dietary zinc levels (P < 0.05). Besides, shell thickness (P = 0.069), plasma testosterone (P = 0.008), LH, and carbonic anhydrase contents (P < 0.05) tended to be affected or significantly affected by zinc addition. They increased linearly as dietary zinc level increased (P < 0.05). Compared with the control, 60 mg/kg zinc addition increased egg production rate, egg shape index, zinc and calcium contents in eggshell, and plasma testosterone concentration in pigeons (P < 0.05), and tended to increase the eggshell percentage (P = 0.07). Besides, supplemental 120 mg/kg zinc had higher shell thickness and LH content than control (P < 0.05), but had no difference with 60 mg/kg zinc addition. In conclusion, the supplementation of zinc at the level of 60 mg/kg to basal diet improved laying performance by increasing eggshell quality and sex hormone levels of breeding pigeons.

Revisiting glucose regulation in birds - A negative model of diabetes complications

Birds naturally have blood glucose concentrations that are nearly double levels measured for mammals of similar body size and studies have shown that birds are resistant to insulin-mediated glucose uptake into tissues. While a combination of high blood glucose and insulin resistance is associated with diabetes-related pathologies in mammals, birds do not develop such complications. Moreover, studies have shown that birds are resistant to oxidative stress and protein glycation and in fact, live longer than similar-sized mammals. This review seeks to explore how birds regulate blood glucose as well as various theories that might explain their apparent resistance to insulin-mediated glucose uptake and adaptations that enable them to thrive in a state of relative hyperglycemia.

Effects of Zinc Methionine Hydroxy Analog Chelate on Laying Performance, Serum Hormone Levels, and Expression of Reproductive Axis Related Genes in Aged Broiler Breeders

Inorganic zinc (Zn) supplements are commonly used in poultry feeds, but their low utilization results in the increase of Zn excretion. Thus, to provide a new perspective for the substitution of inorganic Zn, a novel Zn methionine hydroxy analog chelate (Zn-MHA) was studied in the present study to evaluate its effects on laying performance, serum hormone indexes and reproductive axis-related genes in broilers breeders. A total of 480 Hubbard breeders (56-week-old) were fed a basal diet (containing 27.81 mg Zn/kg) without Zn addition for 2 weeks, and then allocated to 4 groups with 6 replicates (each replicate consisting of 10 cages and 2 breeders per cage) for 10 weeks. Four treatment diets given to broiler breeders included the basal diet added with 25, 50, and 75 mg/kg of Zn-MHA and 100 mg/kg of Zn sulfate (ZnSO₄). The laying rate, egg weight and feed conversation ratio increased in the 75 mg/kg Zn-MHA group compared to the ZnSO₄ group. The eggshell thickness was not decreased with the addition of 50 mg/kg and 75 mg/kg Zn-MHA in the diet compared to the 100 mg/kg ZnSO₄ group. There was a significant improvement in the reproductive performance of breeders in the 75 mg/kg Zn-MHA group, including the fertility and 1-day-old offspring weight. Besides, serum sex hormone levels including FSH and P₄ increased significantly in 75 mg/kg Zn-MHA group. No significant effect on the ovarian weight or the number of follicles in broiler breeders was observed by supplementing Zn-MHA. Compared to the 100 mg/kg ZnSO₄ group, dietary supplementation with 75 mg/kg of Zn-MHA showed an up-regulation of the FSHR mRNA in the granular layer of follicles. However, dietary supplementation of Zn-MHA had no effects on mRNA expressions of the ovarian LHR and PRLR genes. These findings reinforce the suggestion that Zn-MHA (75 mg/kg) could replace ZnSO₄ (100 mg/kg) as a Zn supplement in diet of broiler breeders, which resulted in better laying and reproduction performances by regulating the expression levels of reproductive axis related genes and serum hormone levels.

Effects of Dietary Indole-3-Acetate Sodium on Laying Performance, Egg Quality, Serum Hormone Levels and Biochemical Parameters of Danzhou Chickens

This study was conducted to investigate the effects of indole-3-acetate sodium (IAA-Na) inclusion in diets on the egg production performance, egg quality, intestinal tissue morphology, serum hormone levels and biochemical parameters of Danzhou chickens to preliminarily explore the efficacy of IAA-Na as a feed additive. A total of 192 Danzhou chickens (50 weeks old) were randomly assigned to 2 groups of 96. The diets for the treatment group consisted of the basal diets, supplemented with IAA-Na (200 mg/kg). The formal feeding trial lasted for four weeks. The results showed that the feed supplemented with IAA-Na not only increased the laying rate (p < 0.05) and egg yolk ratio (0.05 < p < 0.1), but also significantly reduced the feed:egg ratio (p < 0.05). In addition, the dietary supplementation of IAA-Na significantly increased the serum estradiol levels (p < 0.05) and decreased serum alkaline phosphatase activity (p < 0.05). Compared with the control group, the addition of IAA-Na to the diet had no significant effect on the intestinal tissue morphology or serum antioxidant capacity of Danzhou chickens. This study preliminarily provides evidence that dietary IAA-Na can improve laying performance, indicating that IAA-Na is a potentially effective feed additive for laying hens, but further studies are required before arriving at definite conclusions.

Effects of photoperiod on performance, ovarian morphology, reproductive hormone level, and hormone receptor mRNA expression in laying ducks

We investigated the effect of photoperiod on performance, ovarian morphology, reproductive hormones levels, and their receptors mRNA expressions in laying ducks. After adaption, 300 252-day-old Jinding laying ducks were randomly allocated to 5 groups, receiving 12L:12D, 14L:10D, 16L:8D, 18L:6D, or 20L:4D, respectively. Each treatment had 6 replicates of 10 birds each. The feeding trial lasted 8 wk. Egg production, egg mass, and ADFI increased linearly and quadratically with increasing photoperiods (P < 0.05), and the higher values of them occurred in photoperiods ≥ 16 h, compared with 12L:12D (P > 0.05). Initial and bare stroma weight increased quadratically, while total large white follicle (LWF) number and weight increased linearly and quadratically, with increasing photoperiods (P < 0.05). The higher values of them occurred in 16L:8D and 18L:6D treatments as well as the higher total LWF weight also occurred in 20L:4D, compared with 12L:12D (P > 0.05). Besides, 16.93 and 16.93 h were the optimal photoperiods for bare stroma (follicles ≥ 2 mm in diameter removed) weight and total LWF weight, respectively, calculated from reliable regression equations (R² ≥ 0.5071). Compared with 12L:12D, the higher levels of estradiol, progesterone, follicle-stimulating hormone (FSH) as well as the higher expressions of estrogen, luteinizing hormone (LH) and progesterone receptors were observed in ≥16 h photoperiods (P < 0.05), while the higher LH level and FSH receptor expression only occurred in 16L:8D and 18L:6D (P < 0.05). In the hypothalamus, higher mRNA expression of gonadotropin-releasing hormone occurred in 16L:8D and 18L:6D groups (P < 0.05). Meanwhile, gonadotropin-inhibitory hormone and prolactin increased in 20-hour photoperiod (P < 0.05), and the latter may be due to theup-regulation of vasoactive intestinal peptide expression (P < 0.05). To sum up, an appropriate photoperiod could improve the performance and reproductive organ and ovarian follicles development through reproductive hormones and their receptors, and 16.56 to 10.93 h is an adequate photoperiod for laying ducks.

Dietary combined supplementation of iron and Bacillus subtilis enhances reproductive performance, eggshell quality, nutrient digestibility, antioxidant capacity, and hematopoietic function in breeder geese

A 3 × 2 factorial arrangement of treatments was conducted to investigate the effects of iron (Fe, 40, 60, and 80 mg/kg) and Bacillus subtilis (2.5 × 10⁹ and 5.0 × 10⁹ CFU/kg) supplementation on reproductive performance, egg quality, nutrient digestibility, hormone levels, antioxidant indices, and hematological parameters in breeder geese. A total of one hundredtwenty 46-week-old Wulong breeder geese were randomly assigned to 1 of 6 dietary treatments with 4 replicates per treatment and 5 geese per replicate for 10 wk following 1 wk of adaption. Dietary Fe supplementation increased egg weight (P = 0.036), fertility (P = 0.022), serum total antioxidant capacity (P = 0.022), red blood cell (P = 0.001), hematocrit (HCT, P < 0.001), hemoglobin (HGB, P = 0.005), and mean corpuscular volume (MCV, P < 0.001). Dietary B. subtilis supplementation increased egg production (P = 0.025), eggshell thickness (P = 0.020), apparent phosphorus digestibility (P < 0.001), serum follicle stimulating hormone (P = 0.043), total antioxidant capacity (P < 0.001), HCT (P < 0.001), HGB (P < 0.001), and MCV (P = 0.025), and reduced malondialdehyde level (P = 0.008). The birds fed diets supplemented with 60 mg/kg Fe and 5 × 10⁹ CFU/kg B. subtilis showed the highest percentage of hatched eggs (P = 0.004) and mean corpuscular hemoglobin (P < 0.001) among the 6 groups. Supplementation of 40 and 60 mg/kg Fe significantly increased the apparent digestibility of calcium compared with that of 80 mg/kg Fe in the birds fed 5.0 × 10⁹ CFU/kg B. subtilis (P = 0.004). Supplementation with 60 and 80 mg/kg Fe in the birds fed 5 × 10⁹ CFU/kg B. subtilis significantly decreased serum urea nitrogen level compared with other 4 groups (P = 0.022). In conclusion, the combination of Fe and B. subtilis effectively improves reproductive performance, eggshell quality, nutrient digestibility, antioxidant status, and hematopoietic function of breeder geese. Dietary addition of 60 mg/kg Fe and 5.0 × 10⁹ CFU/kg B. subtilis was an optimum supplementation dose.

Effect of photoperiod on ovarian morphology, reproductive hormone secretion, and hormone receptor mRNA expression in layer ducks during the pullet phase

We evaluated the effect of photoperiod on ovarian morphology, reproductive hormone secretion, and hormone receptor mRNA expression in layer ducks during the pullet phase. A total of 480 71-d-old Jinding layer ducks were randomly divided into 5 groups that received 6L (hours of light):18D (hours of darkness), 8L:16D, 10L:14D, 12L:12D, or 14L:10D, respectively. Each group had 6 replicates with 16 birds each. The photoperiod feeding trial lasted 80 d until 150 d of age. The age at first egg (AFE), the total number, and weight of eggs increased linearly with increasing photoperiods (P < 0.05); lower values of AFE occurred with photoperiods ≥8 h, whereas a higher total number and weight of eggs occurred with photoperiods ≥10 h, compared with 6L:18D (P > 0.05). Oviduct weight, ovary percentage, and initial and bare stroma (weight and percentage) increased quadratically with increasing photoperiods (P < 0.05), and 10.24, 10.01, and 10.10 h were the optimal photoperiods for oviduct weight, bare stroma (follicles ≥2 mm in diameter removed) weight, and bare stroma percentage, respectively, as calculated from reliable regression equations (R2 ≥ 0.5791). Compared with 6L:18D, 10L:14D had a higher total large white follicle weight, small yellow follicle number, and weight (P < 0.05). In addition, higher serum levels of follicle-stimulating hormone, luteinizing hormone, and progesterone were observed with ≥10-h photoperiods (P < 0.05), as were levels of hormone receptor mRNA expression in ovarian follicles (P < 0.05), with the highest values for both measures at 10L:14D. In the hypothalamus, mRNA expression of gonadotropin-releasing hormone increased in ≥8-h photoperiods, with the highest value at 10L:14D. In contrast, gonadotropin-inhibitory hormone increased in photoperiods ≥12 h (P < 0.05). In conclusion, an appropriate photoperiod led to early sexual maturity and improved the development of reproductive organs and ovarian follicles through effects on reproductive hormones and their receptors; 10 to 10.24 h is an adequate photoperiod for layer ducks during the pullet phase.

Effects of rearing systems on reproductive hormones secretion and their receptors gene expression in Xianju chickens under summer conditions

Previous study in our lab showed that indigenous Xianju chickens from free-range system (FRS) under summer conditions had lower egg production than those from conventional cage rearing system (CRS). The objective of this study was to preliminarily determine the FRS-dependent mechanism of depressing laying performance according to determining the effect of rearing systems on reproductive hormones secretion and their receptors mRNA expression in Xianju chickens reared under summer conditions. A total of 360 indigenous Xianju chickens were randomly allocated to CRS and FRS groups, each of which included 5 replicates of 36 hens. The experiment lasted between 21 and 29 wk of age. We found that the ovarian weight, numbers of small yellow follicles, and large white follicles in the FRS group were lower than those in the CRS group (P < 0.05). Changing from CRS to FRS increased serum concentrations of prolactin and decreased serum-luteinizing hormone and progesterone levels (P < 0.05). Gene expressions in the preovulatory follicles from FRS hens were upregulated for prolactin receptor and downregulated for luteinizing hormone receptor and progesterone receptor, compared to those from CRS hens (P < 0.05). It can be concluded that changing from CRS to FRS in the current experimental conditions depressed egg production traits in Xianju chickens by inducing a synergistic activity of reproductive hormones and the gene expressions of their receptors.

Effects of dietary octacosanol supplementation on laying performance, egg quality, serum hormone levels, and expression of genes related to the reproductive axis in laying hens

This experiment was conducted to evaluate the effects of dietary octacosanol supplementation on laying performance, egg quality, serum hormone levels, and gene expression related to reproductive axis in laying hens to confirm the reproduction-promoting function of octacosanol. In total, 360 Hy-Line Brown (67-wk-old) laying hens were randomly assigned to one of three treatments with 0, 5, and 10 mg octacosanol (extracted from rice bran, purity >92%)/kg feed. The feeding trial lasted for 10 weeks. The results showed that the dietary addition of 5 and 10 mg/kg octacosanol improved feed efficiency by 4.9% and 3.4% (P < 0.01), increased the albumen height by 20.5% and 13.3% (P < 0.01), the Haugh unit score by 12.9% and 8.7% (P < 0.01), and the eggshell strength by 39.5% and 24.5% (P < 0.01), respectively, compared with the control diet. Dietary octacosanol addition significantly affected serum triiodothyronine, estradiol, follicle-stimulating hormone levels (P < 0.05), and progesterone and luteinizing hormone level (P < 0.01). Compared with the control, dietary addition of octacosanol at 5 mg/kg promoted the follicle-stimulating hormone receptor (FSHR) mRNA expression in different-sized follicles, and significantly increased the FSHR mRNA expression of granulosa cells from the F2 and F3 follicles (P < 0.05). Dietary supplementation with both 5 and 10 mg/kg octacosanol promoted the mRNA expression of luteinizing hormone receptor and prolactin receptor in different-sized follicles, and significantly up-regulated the expression levels in F1 granulosa cells (P < 0.05). The ovarian weight was significantly increased with the dietary addition of 5 mg/kg octacosanol (P < 0.05). The numbers of small yellow follicles and large white follicles were increased with the addition of dietary 5 and 10 mg/kg octacosanol (P < 0.01). This study provides evidence that octacosanol has the capacity to improve reproductive performance, indicating that it is a potentially effective feed additive in egg production.

The seasonal glucocorticoid response of male Rufous-winged Sparrows to acute stress correlates with changes in plasma uric acid, but neither glucose nor testosterone

We sought to clarify functional relationships between baseline and acute stress-induced changes in plasma levels of the stress hormone corticosterone (CORT) and the reproductive hormone testosterone (T), and those of two main metabolites, uric acid (UA) and glucose (GLU). Acute stress in vertebrates generally stimulates the secretion of glucocorticoids, which in birds is primarily CORT. This stimulation is thought to promote behavioral and metabolic changes, including increased glycemia. However, limited information in free-ranging birds supports the view that acutely elevated plasma CORT stimulates glycemia. Acute stress also often decreases the secretion of reproductive hormones (e.g., T in males), but the role of CORT in this decrease and the contribution of T to the regulation of plasma GLU remain poorly understood. We measured initial (pre-stress) and acute stress-induced plasma CORT and T as well as GLU in adult male Rufous-winged Sparrows, Peucaea carpalis, sampled during the pre-breeding, breeding, post-breeding molt, and non-breeding stages. Stress increased plasma CORT and the magnitude of this increase did not differ across life history stages. The stress-induced elevation of plasma CORT was consistently associated with decreased plasma UA, suggesting a role for CORT in the regulation of plasma UA during stress. During stress plasma GLU either increased (pre-breeding), did not change (breeding), or decreased (molt and non-breeding), and plasma T either decreased (pre-breeding and breeding) or did not change (molt and non-breeding). These data provide only partial support to the hypothesis that CORT secretion during acute stress exerts a hyperglycemic action or is responsible for the observed decrease in plasma T taking place at certain life history stages. They also do not support the hypothesis that rapid changes in plasma T influence glycemia.

Egg quality and production performance of laying hens injected with growth hormone and testosterone in the late phase of production

In this study, 160 73-week-old laying hens (HyLine W-36) were used to investigate the changes in production performance and egg quality parameters of aged laying hens after injection of different doses of growth hormone (GH) and a fixed dose of testosterone (Ts). The hens were weighed individually, placed in laying cages and then randomly assigned to four treatments with four replicates of 10 birds each, in a completely randomised design. The experiment was started at the 75th week and lasted until the 82nd week of age. The treatments were: 1: injection of 100 µL distilled water (control group), 2: injection of 500 µg Ts/kg liveweight + 50 µg GH/kg liveweight, 3: injection of 500 µg Ts/kg liveweight + 100 µg GH/kg liveweight and 4: injection of 500 µg Ts/kg liveweight + 150 µg GH/kg liveweight. In this study, ovulation rate (egg production percent), egg mass and feed intake were significantly higher in Treatment 3 than the control group (P < 0.05), and in Treatment 4, feed conversion ratio was significantly higher than for the other experimental groups (P < 0.05). In addition, the birds in Treatment 3 showed greater egg weight, albumen height, eggshell weight, eggshell density and eggshell weight per surface area than the control group (P < 0.05). In Treatment 3, egg length significantly increased compared with Treatments 1 and 4 (P < 0.05), and in Treatments 2 and 4, shell breaking strength was significantly lower than for the control group (P < 0.05). In conclusion, our results showed positive effects of GH and Ts administration on egg quality parameters and production performance in aged laying hens. Taken together, in the present study Treatment 3 was found more effective in improving egg quality and production performance of the old laying hens.