Effects of catecholamines on ovary morphology, blood concentrations of estradiol-17beta, progesterone, zinc, triglycerides and rate of ovulation in domestic hens

Influence of Dietary Probiotic and Alpha-Monolaurin on Performance, Egg Quality, Blood Constituents, and Egg Fatty Acids' Profile in Laying Hens

This work was designed to evaluate the advantages of using multi-strain probiotics feed (Bacillus subtilis, Bacillus licheniformis and Clostridium butyricum) (PRO) and alpha-monolaurin (AML) on laying performance, criteria of egg quality, blood parameters, and yolk fatty acids' profile in laying hens. One hundred forty of Bovans brown laying hens at 45 weeks old (25th week of egg production) were randomly allocated into four groups, with seven replicates of five birds each in a complete randomized design. The first group was fed a basal diet without feed additives (0 g/kg diet), and the second, third, and fourth groups received diets containing 1 g PRO, 1 g AML, and 1 g PRO + 1 g AML/kg diet, respectively. No significant impacts of PRO, AML, or their mixture on body weight (BW), body weight gain (BWG), feed intake (FI), or egg weight. Egg production, egg mass, and feed conversion ratio (FCR) were enhanced by 1 g PRO/kg and /or 1 g AML/kg supplementation in laying hen diets. Furthermore, egg shape index, eggshell thickness, and yolk color were statistically higher by PRO and AML supplementation at 55 weeks. However, oviduct, infundibulum, and uterus weights were significantly decreased by 1 g PRO or/and 1 g AML. Additionally, total cholesterol, triglycerides, low density lipoprotein (LDL), glucose, and glutamate pyruvate transaminase (GPT) levels were decreased by PRO and AML supplementation. In conclusion, it seems that dietary inclusion with 1 g PRO/kg, 1 g of AML/kg, and 1 g PRO + 1 g AML improved egg production, egg mass, FCR, and yolk fatty acids profile and lowered total cholesterol and malondialdehyde (MDA) contents in laying hens.

Antioxidant Status, Lipid Metabolism, Egg Fatty Acids, and Nutritional Index of White-Egg Laying Hens Fed Flaxseed Cake

Flaxseed cake contains high levels of phenolic compounds, which have numerous biological activities, as well as a considerable amount of omega-3 fatty acids, such as α-linolenic acid, which remains after oil extraction. In this study, we examined the effects of flaxseed cake meal (FSCM) on the antioxidative status, lipid metabolism, egg fatty acid profile, and egg health index of white-egg laying hens. A total of 63 Hisex White laying hens were divided into three experimental treatment groups and fed diets containing 0, 5, or 10% FSCM from 48 to 58 weeks of age. Feeding with 5 and 10% FSCM did not significantly (p>0.05) influence total lipid, triglyceride, total cholesterol, very low-density lipoprotein-cholesterol, or low-density lipoprotein-cholesterol concentrations, or the high-/low-density lipoprotein ratio in the serum and egg yolk; however, 10% FSCM significantly (P<0.05) increased serum high-density lipoprotein. Dietary FSCM also did not affect (P>0.05) antioxidant markers in the eggs and blood plasma. Notably, dietary inclusion of FSCM significantly increased (P<0.05) total n-3 polyunsaturated fatty acids (PUFAs), α-linolenic acid, docosahexaenoic acid, and eicosapentaenoic acid levels in egg yolk, whereas the n-6:n-3 PUFAs ratio was markedly (P<0.05) decreased in a dose-dependent manner. Moreover, including 5-10% FSCM improved (P<0.05) egg health indices, with 10% being the most beneficial. Together, these findings indicated that the inclusion of up to 10% FSCM in laying hen diets improved egg yolk lipid and fatty acid profiles, as well as egg quality and nutritional and metabolic indices.

Dietary flaxseed cake influences on performance, quality, and sensory attributes of eggs, serum, and egg trace minerals of laying hens

Nowadays, there is a global shortage in feed supply for animal nutrition; however, there are a considerable amount of agro-industrial co- and by-products that may offer a reasonable solution. Flaxseed cake (FSC) is a by-product of flaxseed for oil extraction rich in n-3 α-linolenic acid (ALA). Thus, the dietary inclusion of FSC on laying performance, egg quality, and serum and egg trace elements (Se, Zn, and Fe) was evaluated using Hisex White hens. The hens were distributed to three equal experimental treatments and provided diets including 0%, 5%, or 10% FSC from 48 to 58 weeks of age. Findings clarified that up to 10% FSC in the laying hen diet had no detrimental effect on laying rate, egg mass, and feed utilization. It was found that FSC resulted in a valuable source of protein, energy, macro- (Ca and P), micro- (Se, Zn and Fe) elements, and essential amino acids, with arginine being the highest. Dietary FSC did not negatively influence the egg quality traits, as well as egg sensory attributes. Including 5% or 10% FSC in diet did not significantly affect serum total protein and renal function in terms of creatinine, uric acid, and uric acid-to-creatinine ratio. Different FSC levels did not influence the chemical composition of eggs and trace elements in serum and eggs. It could be concluded that FSC is a valuable feedstuff that can provide a good source of energy, protein, amino acids, and macro- and micro-elements for hens' nutrition. The inclusion of up to 10% of FSC in hens diet did not adversely influence egg laying performance, egg quality of both fresh and stored eggs, sensory attributes, and nutritional composition, as well as Se, Zn, and Fe in serum and eggs due to balanced nutrient profile of FSC.

Estradiol-17ß Is Influenced by Age, Housing System, and Laying Performance in Genetically Divergent Laying Hens (Gallus gallus f.d.)

The estrogen estradiol-17ß is known as one of the major gonadal steroid hormones with different functions in reproduction. In this study we analyzed estradiol-17ß concentration in laying hens of four pure bred chicken laying lines at four different time intervals of the laying period (17th-19th week of age, 33rd-35th week of age, 49th-51st week of age, and 72nd week of age). The high performing white egg (WLA) and brown egg (BLA) layer lines as well as the low performing white (R11) and brown (L68) layer lines were kept in both single cages and a floor housing system. We investigated whether there were differences in estradiol -17ß concentrations between lines at different ages that could be related to selection for high egg production or phylogenetic origin of the animals, and whether there was an influence of housing conditions on estradiol-17ß. Estradiol-17ß concentrations differed between high and low performing layer lines at all time intervals studied. High performing hens showed higher estradiol-17ß concentrations compared to low performing hens. In all lines, highest estradiol-17ß concentration was measured at their 49th to their 51st week of age, whereas the peak of laying intensity was observed at their 33rd to their 35th week of age. Additionally, hens with fewer opportunities for activity housed in cages showed higher estradiol-17ß concentrations than hens kept in a floor housing system with more movement possibilities. We could show that laying performance is strongly linked with estradiol -17ß concentration. This concentration changes during laying period and is also influenced by the housing system.

Characterization of Chicken α2A-Adrenoceptor: Molecular Cloning, Functional Analysis, and Its Involvement in Ovarian Follicular Development

Adrenoceptors are suggested to mediate the functions of norepinephrine (NE) and epinephrine (EPI) in the central nervous system (CNS) and peripheral tissues in vertebrates. Compared to mammals, the functionality and expression of adrenoceptors have not been well characterized in birds. Here, we reported the structure, expression, and functionality of chicken functional α_2A-adrenoceptor, named ADRA2A. The cloned chicken ADRA2A cDNA is 1335 bp in length, encoding the receptor with 444 amino acids (a.a.), which shows high amino acid sequence identity (63.4%) with its corresponding ortholog in humans. Using cell-based luciferase reporter assays and Western blot, we demonstrated that the ADRA2A could be activated by both NE and EPI through multiple signaling pathways, including MAPK/ERK signaling cascade. In addition, the mRNA expression of ADRA2A is found to be expressed abundantly in adult chicken tissues including thyroid, lung, ovary and adipose from the reported RNA-Seq data sets. Moreover, the mRNA expression of ADRA2A is also found to be highly expressed in the granulosa cells of 6–8 mm and F5 chicken ovarian follicles, which thus supports that ADRA2A signaling may play a role in ovarian follicular growth and differentiation. Taken together, our data provide the first proof that the α_2A-adrenoceptor is functional in birds involving avian ovarian follicular development.

Productive Performance, Ovarian Follicular Development, Lipid Peroxidation, Antioxidative Status, and Egg Quality in Laying Hens Fed Diets Supplemented with Salvia officinalis and Origanum majorana Powder Levels

This study aimed to assess the effect of dietary supplementation with different levels of Salvia officinalis and/or Origanum majorana on productive performance, ovarian follicular development, lipid peroxidation, antioxidative status, and egg quality in laying hens. Two hundred and ninety-four 45-week-old Bovans brown hens were allocated into seven groups, with seven replicates of six hens each. The first group was fed with the basal considered as a control (A); the second (B) and third (C) groups were provided with the same control diet further supplemented with 0.5 and 1 kg/ton Salvia officinalis, respectively; the fourth (D) and fifth (E) groups received the control diet further supplemented with 0.5 and 1 kg/ton Origanum majorana, respectively; while the sixth (F) and the seventh (G) groups were offered a diet supplemented with 0.5 kg/ton Salvia officinalis and 0.5 kg/ton Origanum majorana and 1 kg/ton Salvia officinalis and 1 kg/ton Origanum majorana, respectively. No significant effects were observed in the final body weight (BW) and feed intake (FI) of the laying hens. In the diets supplemented with Salvia officinalis and Origanum majorana, the egg weights for groups C, F, and G had significantly higher values only compared to group D. The supplementation of the diets with Salvia officinalis and/or Origanum majorana significantly (p < 0.05) increased the Follicle stimulating hormone (FSH), luteinizing hormone (LH), and estradiol estrogenic hormone concentration, except for Origanum majorana at both levels with regard to estradiol. The dietary utilization of Salvia officinalis and Origanum majorana did not significantly alter the plasma glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT), total protein, albumin, globulin, and High density lipoprotein (HDL) parameters. Cholesterol, glucose, triglyceride, and Low density lipoprotein (LDL) were decreased (p < 0.05) in the birds fed with Salvia officinalis and/or Origanum majorana supplemented diets. Moreover, at both doses, the dietary supplementation with Salvia officinalis and Origanum majorana decreased (p < 0.05) the yolk cholesterol and liver Malondialdehyde (MDA) levels. In addition, the dietary enrichment with Salvia officinalis and/or Origanum majorana decreased (p < 0.05) the palmitoleic and stearic fatty acids' egg yolk concentration. In contrast, the yolk linoleic fatty acid concentration was significantly increased by Salvia officinalis and/or Origanum majorana. In conclusion, dietary supplementation with Salvia officinalis and/or Origanum positively affected productive performance, ovarian follicular development, antioxidant activity, hormonal status, and steroidogenesis in Bovans brown laying hens.

The stimulation and inhibition of beta-2 adrenergic receptor on the inflammatory responses of ovary and immune system in the aged laying hens

Background

Ovarian chronic inflammation has been known to incidence in the laying hen mainly via increasing laying frequency and microbial infection, especially during late stage of production period. This study was aimed to evaluate beta-2 adrenergic agonist (Beta-2 Adrenergic Agonist, BAA) Salmeterol and beta blocker (Beta Blocker, BB) Propranolol on the gene expression of the ovarian pro- and anti-inflammatory mediators, inflammatory responses of immune system, ovarian functions and, hormones in the laying hens on the late stage of production period. Forty-eight White Leghorn hens aged 92 weeks were used for 4 weeks to be supplemented by Salmeterol and Propranolol. Ovulation rate and follicular growth were determined based on laying frequency and ovarian visual evaluation, respectively; the mRNA expressions of follicular beta-2 adrenergic receptor (Beta-2 Adrenergic Receptor, β2ADR), cyclooxygenases (Cyclooxygenases, COX) 1 and 2, and cytokines were measured by real-time PCR. The plasma concentration of ovarian hormones, cellular, and humoral immune responses were measured via ELISA, heterophil to lymphocyte ratio (Heterophil to Lymphocyte ratio, H:L), and sheep red blood cell (Sheep Red Blood Cell, SRBC) test, respectively.

Results

As compared to control, both of BAA Salmeterol and BB Propranolol resulted in a significant decrease in the mRNA expression of β2ADR, cyclooxygenases, and pro- and anti-inflammatory cytokines (P < 0.01). A significant elevation was observed in the ovulation rate (P < 0.05), plasma estradiol content on both treated groups (P < 0.05), and the content of progesterone and was just significantly (P < 0.05) increased in Salmeterol group. H:L was reduced in BAA group (P < 0.05), and immunoglobulin (Ig) M was elevated in both treated hens, when compared to control. The results indicated that Salmeterol significantly increases body weight (P < 0.05).

Conclusion

The stimulation and inhibition of beta-2 adrenergic signaling could reduce ovarian inflammatory condition in addition to enhancing laying efficiency in the aged laying hens.

Effect of Bacterial or Fungal Phytase Supplementation on the Performance, Egg Quality, Plasma Biochemical Parameters, and Reproductive Morphology of Laying Hens

Simple Summary

The present study shows that 5000 FTU/kg dietary supplementation with bacterial (E. coli) or fungal (Aspergillus niger and Trichodermareesei) sources of phytase with less available phosphorus is capable of maintaining productive efficiency, reproductive morphology, and egg quality of laying hens. Eggshell consistency was increased while yolk cholesterol was decreased as a result of diets supplemented with bacterial or fungal phytase. All in all, our results clarify that feeding laying hens bacterial and fungal phytase at 5000 FTU/kg can be effective to replace inorganic phosphorus commercially.

Abstract

Catalytic and physicochemical properties of microbial phytase sources may differ, affecting phosphorus (P) release and subsequently the productive and reproductive performance of layers. The current study aimed to evaluate the impact of bacterial and fungal phytase sources on layer productivity, egg production, biochemical blood indices, and reproductive morphology. For this purpose, 360 Bovans brown hens at 42 weeks of age were randomly allocated into 4 experimental groups, each with 15 replicates of 6 hens. The first group (control) was fed a basal diet with 4.6 g/kg available P. In contrast, the second, third, and fourth groups were fed diets treated with 3.2 g/kg available P, supplemented with either 5000 FTU/kg of bacterial E. coli (Quantum^TM Blue 5G), fungal Aspergillus niger (VemoZyme^® F 5000 Naturally Thermostable Phytase (NTP)), or fungal Trichodermareesei (Yemzim^® FZ100). Dietary supplementation of bacterial and fungal phytases did not affect the productive performance or egg quality criteria, except for increased shell weight and thickness (p < 0.05). Serum hepatic function biomarkers and lipid profiles were not altered in treated hens, while calcium and P levels were increased (p < 0.05) related to the controls. Ovary index and length, and relative weight of oviduct and its segments were not influenced. The contents of cholesterol and malondialdehyde in the yolks from treated birds were lower compared to control hens, while calcium and P content increased (p < 0.05). Conclusively, bacterial and fungal phytase sources can compensate for the reduction of available P in layers’ diets and enhance shell and yolk quality without affecting productive performance, and no differences among them were noticed.

Effect of anti-müllerian hormone on the development and selection of ovarian follicle in hens

To elucidate the role of anti-müllerian hormone (AMH) in regulating the development of ovarian follicles in laying hens, the expressions of follicle-stimulating hormone receptor (FSHR), AMH receptor type 2 (AMHR2), steroidogenic-related genes steroidogenic acute regulatory protein (STAR), cytochrome P450 side-chain cleavage (CYP11A1), and 3β-hydroxysteroid dehydrogenase (HSD3B1) genes were measured from different sized follicles and granulosa cells. The results showed that the expressions of FSHR and AMHR2 genes were higher in small follicles and decreased after follicular selection. Oppositely, the expressions of STAR, CYP11A1, and HSD3B1 were significantly increased after follicular selection. It indicated that AMHR2 might mediate AMH suppression in the stimulating effects of follicle-stimulating hormone (FSH) on steroidogenic-related genes expression. To make sure the effects of AMH in this process, a total of 40 hens were treated (negative control, sham operation, 150 ng AMH/d or 300 ng AMH/d) for 25 d. We analyzed ovarian morphology, progesterone concentration in blood plasma, and the expressions of steroidogenic genes in ovaries and follicles. The AMH300 group had significantly lower weight of ovary and hierarchical follicles. Egg weight and ovary weight in AMH150 group were higher than those of sham operation and AMH300 groups, so did hierarchical follicles weight. The steroidogenic genes expressions showed an increase in ovarian tissue and the largest follicle of AMH150 and AMH300 groups. However, progesterone level in the blood was reduced by AMH injection with different concentrations. To further verify the above results, granulosa cells from 6 to 8 mm follicles were cultured with AMH (0, 5, 10, 20, 40, or 80 ng/mL). The results revealed that excessive AMH (80 ng/mL) exerted an inhibitory effect on progesterone synthesis and the expressions of STAR, CYP11A1, and HSD3B1. However, these genes expressions showed a significant increase in 20 ng/mL AMH-treated group. In summary, AMH inhibited the development of prehierarchical follicles in laying hens. The effects of AMH treatment with different concentrations on follicle development showed the follicle was selected by changing FSH responsiveness of prehierarchical follicles.

Impact of Dietary Organic Mineral Supplementation on Reproductive Performance, Egg Quality Characteristics, Lipid Oxidation, Ovarian Follicular Development, and Immune Response in Laying Hens Under High Ambient Temperature

The objectives of this study were to investigate the impact of dietary organic mineral mixture (manganese, zinc, and copper) supplementation on reproductive performance, egg quality characteristics, and immune response in laying hens under high ambient temperature. Hens were randomly divided into three treatments: (1) control (basal diet without organic mineral mixture (Mn, Zn, and Cu) supplementation); (2) basal diet + 0.5 g/kg of organic mineral mixture; and (3) basal diet + 1 g/kg of organic mineral mixture from 30 to 38 weeks of age. Hen-day egg production and egg mass were significantly increased by dietary supplementation of 1 g/kg of organic mineral mixture, while feed intake was not affected; therefore, feed conversion ratio (FCR) was significantly improved (P < 0.01). Egg weight, albumen width, shell weight, and shell thickness were significantly increased by the dietary treatments. Serum total cholesterol and glucose were significantly decreased by organic mineral mixture supplementation. Interestingly, yolk contents of total cholesterol and malondialdehyde (MDA) were significantly decreased. Yolk contents of Zn and Cu were significantly increased, while Mn was numerically increased (P > 0.05). Dietary organic mineral mixture supplementation improved the antibody titers against avian influenza H9N1 significantly (P < 0.05) and Newcastle disease virus numerically (P > 0.05) in comparison with the control diet. It might be concluded that the inclusion of organic mineral mixture (Mn, Zn, and Cu) enhanced reproductive performance, shell quality characteristics, plasma profile, yolk mineral concentration, yolk lipid oxidation, and immune response in laying hens under high ambient temperature.

The impact of phytoestrogen source supplementation on reproductive performance, plasma profile, yolk fatty acids and antioxidative status in aged laying hens

The objectives of this study were to investigate the effects of flaxseeds and/or fenugreek seeds as a source of phytoestrogens in laying feed on productive performance, egg quality, yolk fatty acids, plasma profile and antioxidative status in aged laying hens. A total of 120 Bovans Brown hens at 65 weeks of age were housed individually in laying cages in an open-sided building under a 16-hr light: 8-hr dark lighting schedule. Hens were randomly divided into four experimental treatments (n = 30 each): (a) control (basal diet without any supplementation); (b) 1 g/kg of flaxseeds; (c) 1 g/kg of fenugreek seeds; and (d) combination of 1 g/kg flaxseeds and 1 g/kg fenugreek seeds from 65 to 71 weeks of age. Hen-day egg production and egg mass were significantly increased by dietary supplementation of flaxseeds and/or fenugreek seeds, while feed intake was not affected; thus, feed conversion ratio was improved (p < 0.05). Weights of egg, albumen, yolk and shell were increased by the dietary treatments. Shell thickness and yolk colour were improved by supplementation of flaxseeds and/or fenugreek seeds. Yolk crude protein was not significantly affected by treatments; however, crude fat and calcium contents in yolk were increased and egg yolk cholesterol content was decreased. Interestingly, dietary supplementation of flaxseeds, fenugreek seeds and their combination had a significant positive effect on plasma luteinizing hormone, follicle-stimulating hormone, oestradiol-17β and triglycerides. Inclusion of flaxseeds and/or fenugreek seeds in the diets enhanced the serum glutathione peroxidase and superoxide dismutase activities and reduced the malondialdehyde and total cholesterol concentrations in plasma. Dietary supplementation of flaxseeds and/or fenugreek seeds increased α-linolenic and linoleic acids in egg yolk. It could be concluded that inclusion of mixed sources of phytoestrogens in diets improved laying performance, egg quality, the antioxidative status, hormonal profile and steroidogenesis in aged laying hens.

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.

An in vitro study on catecholamine modulation of ovarian steroidogenic activity in the catfish Heteropneustes fossilis

In the present study, α-methylparatyrosine (α-MPT), a tyrosine hydroxylase inhibitor was used to impair ovarian catecholaminergic activity in vitro. The consequent effects on catecholamine (CA) levels were correlated with follicular steroid production. l-dihdroxyphenylalanine (l-DOPA, the precursor of CA) and human gonadotropin (hCG) were supplemented to reverse the effect of α-MPT. The experiments were conducted in two reproductive phases, namely preparatory and pre-spawning phases in female catfish Heteropneustes fossilis. The incubation with α-MPT inhibited ovarian l-DOPA, dopamine (DA), norepinephrine (NE) and epinephrine (EP) levels and the l-DOPA supplementation compensated the inhibitory effect. The level of tyramine (TR) was increased by the α-MPT treatment but inhibited by the l-DOPA supplementation. α-MPT produced stage-specific (seasonal) effects on ovarian estradiol-17β (E2); in the preparatory phase, E2 was decreased significantly at both 12 and 24h and in the pre-spawning phase, the level was stimulated over the respective control groups. The changes were higher at 24h in both phases. l-DOPA and hCG increased the E2 level significantly in the preparatory phase and reversed the inhibitory effect of α-MPT in the co-incubation groups. In the pre-spawning phase, α-MPT-stimulated the E2 level compared to the control groups, which was reversed by l-DOPA, hCG, or by both, in co-incubations. In contrast, the α-MPT treatment decreased progesterone (P4), 17-hydroxyprogesterone and 17,20β-dihydroxy-4-prenen-3-one (17,20β-DP) in a duration-dependent manner while the co-incubations with l-DOPA, hCG, or by both, significantly reversed the inhibitory effect. These results suggest that ovarian CAs (DA, NE and EP) may exert differential and stage-specific effects on E2, inhibition in the preparative phase and stimulation in the pre-spawning phase. The progestin steroids appear to be stimulated by CAs. In conclusion, this study highlights a possible direct/causal functional interaction between CA activity and gonadotropin on steroidogenic activity, and that CAs may be involved in regulating temporal secretion of the hormones through causing the shift in steroidogenic pattern.

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

The experiment was designed to study the changes in some blood parameters and production performance of old laying hens after injection of different doses of growth hormone (GH) and testosterone (Ts). A total of 160 old laying hens (HyLine W-36) at 73 weeks of age were weighed individually and randomly allocated to four treatments with four replicates and 10 birds in each replicate in a completely randomized design. Growth hormone and Ts hormones were injected subcutaneously. Treatment groups were as follows: treatment 1: injection of 100 μl distiled water (control group), treatment 2: injection of 500 μg Ts/kg live-weight + 50 μgGH/kg live-weight, treatment 3: injection of 500 μgTs/kg live-weight + 100 μgGH/kg live-weight and treatment 4: injection of 500 μgTs/kg live-weight + 150 μgGH/kg live-weight. Plasma levels of oestradiol, T4 , LDL, HDL and cholesterol significantly increased in treatment 3 in relation to the control group. All injected hens showed significantly higher levels of glucose in relation to control group. The results showed the positive effects of GH and Ts administration on production performance and blood parameters which are associated with egg production potentiality and in turn may improve reproductivity (egg production) in old laying hens. The positive results of the study may be useful in animal selection and breeding programmes.

Temporal and periovulatory changes in ovarian catecholamines in the catfish Heteropneustes fossilis

A high performance liquid chromatography-fluorescence detection method was employed to demonstrate temporal and periovulatory changes in ovarian catecholamines in the catfish Heteropneustes fossilis. Tyrosine, L-DOPA, dopamine (DA), norepinephrine (NE) and epinephrine showed significant seasonal and diurnal changes during the reproductive cycle. A high concentration of tyrosine was detected, the values increased in day and decreased in night during recrudescence from preparatory to spawning phases. Similarly, L-DOPA increased during the breeding phase giving the day value concentration peak in the spawning phase and the night value peak in the postspawning phase. DA activity or turnover index (calculated as a ratio of DA to 3,4-dihydroxyphenylacetic acid, DOPAC) showed a bimodal pattern with the major activity peak in the postspawning phase and the minor one in the prespawning phase, the spawning phase registered the lowest activity. NE activity or turnover index (ratio of NE to normetanephrine, NME) increased during the recrudescent phase to give the peak in the spawning phase and decreased in the quiescent phase. Epinephrine elicited an inverse relationship in the day-night pattern, the day values increased to the peak in the spawning phase. All the study correlates showed significant periovulatory changes after hCG treatment. DA activity dropped to the nadir at 8h but recovered at 16 and 24h. NE activity showed only a marginal decrease up to 16h but decreased drastically at 24h. Epinephrine levels remained unchanged but only to increase at 24h. The seasonal patterns and periovulatory changes strongly point to important functions for catecholamines in the ovary. The occurrence of tyramine (an invertebrate neurotransmitter) suggests the presence of alternate catecholamine pathway in fish ovary.

Annual and periovulatory changes in tyrosine hydroxylase activity in the ovary of the catfish Heteropneustes fossilis

In the present study, tyrosine hydroxylase (TH, the rate-limiting enzyme in catecholamine synthesis) activity was demonstrated in the ovary of the catfish to elucidate the possible physiological role of catecholamines in the gonad. The ovary is innervated by seven pairs of nerves, originating from the paired sympathetic chain lying dorsal to the posterior kidney. Ovarian TH activity showed a significant annual variation (P<0.001, one-way ANOVA), correlating with gonado-somatic index. Activity was low from December to February (resting phase), increased from March to July (recrudescent phase) and then decreased in post-spawning phase (August-November). The annual pattern was similar to that of the brain. An intraperitoneal injection of 100 IU hCG/fish induced significant periovulatory changes in TH activity with the peak rise at 16 h, and the activity decreased after egg-stripping (P<0.001, one-way ANOVA). Brain TH activity showed similar periovulatory changes. The results suggest that catecholamine synthesis is increased during both ovarian recrudescence and spawning of the annual reproductive cycle, implying a functional role in ovarian growth, maturation and ovulation.