Adult Pigeons Research Articles

Prevalence of Pigeon Diseases in Sylhet District, Bangladesh

The study was conducted to determine the occurrence of different diseases in pigeon from January to December 2019 at Sylhet District in Bangladesh. A total of 723 pigeons either infected or dead were collected and examined to diagnose the diseases followed by clinical history, clinical signs, and postmortem lesions and laboratory examination. The data were analyzed by using chi-square test. The result, the proportion of bacterial diseases, viral diseases and parasitic diseases were 22.48%, 66.06% and 11.46% in young and 53.31% of viral, 17.4% of bacterial and 29.27% in adult pigeon respectively.

Cryptosporidium spp. in Columba livia Gmelin, 1789 (Columbiformes: Columbidae) free-living pigeons from urban areas in Pelotas, Rio Grande do Sul, Brazil.

Cryptosporidium spp. are parasites with zoonotic potential that cause intestinal diseases, generally intense diarrheal, on their hosts, which tend to be immunocompromised. Large populations of pigeons in urban environments can lead to greater human exposure to Cryptosporidium spp., as this bird is considered a potential reservoir and is able to transmit several pathogens. This study aimed in determining the occurrence of Cryptosporidium spp. oocysts in feces of free-living pigeons (Columba livia) found in urban areas in the city of Pelotas, Rio Grande do Sul, south of Brazil. Fecal samples (n = 50) were collected from young and adult pigeons captured in different locations in the urban area and the parasitological diagnosis was performed through Ritchie's modified technique and Kinyoun's technique. Among the 50 samples, 18% (IC95% 9.7-30.8) were positive for Cryptosporidium spp. with a low number of oocysts being detected on fecal smears. Our results confirmed the occurrence of Cryptosporidium spp. oocysts in feces of free-living pigeons from the urban area of the city of Pelotas. This is the first report of Cryptosporidium spp. oocysts in feces of pigeons in south Brazil. This data has epidemiological significance because the oocysts could be from zoonotic species, which consequently shows that humans might be exposed to infection.

Domestic Pigeons As A Potential Hazzard For Transmission Of Some Human Protozoan Parasites

Domestic pigeons (Columba liviadomestica) of the order Columbiformes are ubiquitous birds and can be found in virtually every town and city around the globe. Their interaction with humans and domestic animals and wild birds makes them a potential carrier of zoonotic parasites. The present study aimed to detect the prevalence of different zoonotic protozoans that affect different-aged domestic pigeons in different localities in Assiut Governorate, Egypt. A total of 50 fecal samples from 20 young and 30 adult pigeons were collected and examined for identification and estimation of prevalence of Cryptosporidium sp. and Microsporidium sp. using modified Kinyoun acid-fast stain. For detection of the prevalence of Toxoplasma gondii, serum samples from 50 pigeons were examined serologically for the presence of Toxoplasma antibodies by using Latex Agglutination test. The prevalence of Cryptosporidium sp. infection was 20%; 6.7% in adult pigeons and 40 % in young pigeons while that of Microsporidium sp. was 40% both in adult and young pigeons. Mixed infection was detected in only two young pigeons (10%). Regarding Toxoplasma gondii detection, the number of seropositive cases detected by LAT was 29 out of 50 (58%). The positive agglutination titers, among 14 (48.27%) seropositive pigeons ranged between 1:2 -1:128. It was concluded that domestic pigeons may be considered as a reservoir host for Cryptosporidium, Microsporidium, and Toxoplasmagondii human infection which represents a serious human public health problem especially for high risk groups of population living in the same dwellings with pigeons. Moreover, the present pilot results provide a baseline data for planning future researches and control strategies against domestic pigeon's parasites.

Smaller on the left? Flexible association between space and magnitude in pigeons (Columba livia) and blue jays (Cyanocitta cristata).

Humans and other apes represent magnitudes spatially, demonstrated by their responding faster and more accurately to one side of space when presented with small quantities and to the other side of space when presented with large quantities. This representation is flexible and shows substantial variability between cultural groups in humans and between and within individuals in great apes. In contrast, recent findings suggest that chicks show a spatial representation of magnitude that is highly lateralized and inflexible, implying a qualitatively different underlying representation than in primates. Using methods similar to those used with great apes and humans, we trained adult domestic pigeons (Columba livia) and blue jays (Cyanocitta cristata) to select the smaller (or larger) of two nonadjacent quantity arrays; later, this task was reversed. At test, birds were presented with novel probe pairs consisting of adjacent quantity pairs (e.g., 2 vs. 3). Both species showed robust evidence for a flexible spatial representation of magnitude with considerable individual variability in the orientation of this representation. These results are not consistent with an inflexible, lateralized, left-to-right representation of magnitude in birds, but are consistent with the flexible spatial representation of magnitude observed in apes and humans. We conclude that the tendency to organize quantities spatially may be a fundamental and evolutionarily ancient feature of cognition that is widespread among vertebrates. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Effects of Mannan Oligosaccharides and/or Bifidobacterium on Growth and Immunity in Domestic Pigeon (Columba livia domestica).

The goal of this study was to evaluate the influences of mannan oligosaccharides (MOSs) and/or Bifidobacterium on the growth and immunity of pigeons over a 56-day period. One hundred paired adult pigeons were randomly divided into four groups of five paired pigeons. Paired pigeons with two young squabs were housed in a man-made aviary. Parent pigeons in the control group received a basal diet (C), while the other three groups were fed with the basal diet supplemented with 20 g of MOSs/kg of feed (M), 10 g Bifidobacterium (1×1010 CFU/g)/kg of feed (B), or a combination of M and B (MB). We found higher body weights (BW) in pigeons of the B group than in the C, M, and MB groups. None of the treatments exerted significant effects involving spleen and thymus indices, whereas M birds tended to improve the bursa of Fabricius index. Pigeons fed with the M-supplemented diet exhibited improved serum immunoglobulin M (IgM) concentrations compared with those fed with C and the B- and MB-supplemented diets. In addition, M treatment increased immunoglobulin A (IgA) levels compared with MB treatment. MB treatment improved serum immunoglobulin G (IgG) concentrations compared to that by the C treatment. The concentration of secretory immunoglobulin A (sIgA) was significantly reduced in the duodenum and increased in the ileum in pigeons fed with the MB-supplemented diet. This study indicated that dietary supplementation with Bifidobacterium increased the growth performance. Dietary supplementation with MOSs or in combination with Bifidobacterium was able to improve immune function in pigeons but exerted no apparent effect on weight gain. Accordingly, in terms of economic benefits, the findings suggested that supplementation with Bifidobacterium alone may improve production performance, and that supplementation with MOSs alone may improve immune function in pigeons.

Formaldehyde-contaminated feed induces histopathological changes in the testes of adult pigeons (Columba livia)

Formaldehyde-contaminated feed induces histopathological changes in the testes of adult pigeons (Columba livia)

The profiling of amino acids in crop milk and plasma and mRNA abundance of amino acid transporters and enzymes related to amino acid synthesis in the crop tissue of male and female pigeons during incubation and chick-rearing periods

The present study was carried out to investigate the changes in amino acid (AA) contents of crop milk and plasma and mRNA abundance of AA transporters and AA synthesis–related enzymes in the crop tissue of male and female pigeons during incubation and chick-rearing periods. Forty-two pairs of adult White King pigeons with 2 fertile eggs per pair were randomly divided into 7 groups by different breeding stages. The AA content of crop milk decreased from day 1 (R1) to day 25 (R25) of chick rearing (P < 0.05). In both male and female adult pigeons, the contents of Thr, Leu, Val, His, Asp, and Pro in plasma increased to maximum levels on R25. Parental sex effect and interaction between stage and sex were observed in the AA contents of pigeon plasma (P < 0.05). For AA transporters, the mRNA abundances of SNAT2, ASCT1, LAT1, and y+LAT2 in the male crops reached the highest value on day 17 of incubation (I17), and the peak mRNA levels of PAT-1, xCT, b0,+AT, and CAT1 were found on R7 (P < 0.05). In females, the abundances of ASCT1, B0AT1, asc-1, and CAT1 mRNA peaked on R1, whereas the maximum levels of LAT1, PAT-1, b0,+AT, and y+LAT2 were observed on R7. For enzymes involved in AA synthesis, the highest gene expressions of glutamate dehydrogenase 1, acetolactate synthase in both parent pigeons, and L-threonine 3-dehydrogenase in female pigeon crops were attained on I17. The expressions of ornithine-δ-aminotransferase, glutamic-oxal(o)acetic transaminase 1, glutamic-oxal(o)acetic transaminase 2, asparagine synthetase, serine hydroxymethyltransferase 2, and glutamic-pyruvic transaminase 2 in both sexes and argininosuccinate lyase and L-threonine 3-dehydrogenase in males were the highest on R1. In conclusion, AA used for pigeon crop milk formation may originate from plasma and intracellular synthesis. The genes involved in AA transport and synthesis varied significantly with sexual effects, indicating that other factors should be considered in future explorations of the mechanism of protein formation in crop milk.

A comparative study on anti-inflammatory drug combinations in domestic pigeons with experimentally induced acute arthritis.

The study compares the effect of one-time administration of nonsteroidal and/or steroidal anti-inflammatory combinations by topical or intramuscular (IM) routes to pigeons with monosodium urate (MSU)-induced arthritis. Forty-five adult domestic pigeons were assigned into nine equal groups: NC, negative control; PC, positive control with arthritis; sham, sham control; T1, meloxicam + hydrocortisone; T2, dexamethasone + piroxicam; T3, meloxicam + dexamethasone; T4, hydrocortisone + piroxicam; T5, dexamethasone + hydrocortisone; T6, meloxicam + piroxicam. Arthritis was also induced in T1 to T6 birds. Meloxicam and dexamethasone were administered by IM injection and the other drugs topically right after the induction of arthritis. Different drug combinations significantly decreased one-leg standing time. Induction of arthritis significantly increased TNF-α and IL-6 levels in synovial fluid and serum corticosterone and epinephrine in the PC group. Administration of drugs to birds of Groups T1 and T5 did not significantly change corticosterone concentration, while all different drug combinations decreased epinephrine level. Drug combinations that demonstrated better analgesic effect more strongly reduced serum epinephrine concentration. Meloxicam + hydrocortisone was the most effective combination in reducing inflammatory cytokines. In conclusion, one-time combination therapy with anti-inflammatory agents was effective in the acute management of inflammatory pain due to MSU-induced arthritis in pigeons, even by the topical route.

Age-related ultrastructural features of the tongue of the rock pigeon Columba livia dakhlae in different three age stages (young, mature, and adult) captured from Egypt.

This study represents the first attempt to describe the ultra-structural and histological features of different three age-stages (young, mature, and adult) of rock pigeon Columba livia dakhlae captured from Egypt. The elongated tongue with round lingual apex carried a lingual nail rostrally on lingual tip. The current work gave a first record of numerous descriptions as in young and mature, small lingual nail formed from aggregation of lingual scales, but in adult, the nail formed from lingual membrane without any lingual scales. The current work gave full descriptive methods of shape, directions, and distribution of filiform-like papillae with lingual scales among three age-stages on dorsal surface and lateral border of apex and body. The taste buds present only on the tongue of mature and adult pigeon. The only one transverse row in young took the wide V-shape but, wide U-shape in mature and adult. The papillae on the papillary crest took triangular spoonful-like shape in young and mature, but in adult take the shape of blunt tubercles. The current work was the first record of the presence of the openings of lingual glands on concave dorsal lingual surface of giant papillae and papillae of papillary crest in adult stage. The lingual membrane was thin one membrane in young and three to four layers in mature but, in adult it is well-developed and formed from 10-11 layers. The supportive entoglossum cartilaginous was extended rostrally till the apical part.

Clinical, Parasitic, and Histopathological Study of Pigeons Infested with Raillietina spp in Al-Qadisiyah Province, Iraq

Pigeons, in Al-Qadisiyah Province-Iraq, were investigated Clinically, parasitically, and histopathologically for the presence of Raillietina spp in their intestines. For these reasons, 5 cities from the mentioned province above were sampled as 150 (100 males and 50 females) pigeons were studied. The general clinical inspection, intestinal exploration and slides for the worms, and histopathological slide sections for the infested intestines were performed. The results of the clinical studies revealed delay growth in the young birds and emaciation in the adult pigeons. For the parasitic characteristics in the intestines, the results showed clearly the presence of Raillietina spp, declaring by their firmly attachment to the mucosa by their suckers and showing their segments, in the lumens of the small intestines. In the case of histopathological pictures, intestines revealed grossly small-intestine-wall-based enlargement and obstruction via intussception caused by the tapeworm presence with huge amounts of mucus and air bubbles and the parasitic white convoluted tracks in the intestinal mucosa. Microscopically, the results recognized that mucosa had mechanical disintegration, marked sloughing of the epithelial layers that belonged to the villi and crypts, epithelial-cell-based desquamation of the villi that were affected by dwarfism, mucosa and submucosa infiltration with mononuclear cells. This study provides important clinical, parasitic, and histopathological data of pigeons infested with Raillietina spp in AlQadisiyah Province, Iraq.

Identification and comparative profiling of gonadal microRNAs in the adult pigeon (Columba livia)

ABSTRACT 1. MicroRNAs are small noncoding RNA molecules that play crucial roles in gene expression. However, the comparative profiling of testicular and ovarian microRNAs in birds are rarely reported, particularly in pigeon. 2. In this study, Illumina next-generation sequencing technology was used to sequence miRNA libraries of the gonads from six healthy adult utility pigeons. A total of 344 conserved known miRNAs and 32 novel putative miRNAs candidates were detected. Compared with those of ovaries, 130 differentially expressed (DE) miRNAs were identified in the testes. Among them, 70 miRNAs showed down-regulation in the ovaries, while another 60 miRNAs were up-regulated. 3. Combining the results of the expression of target gene measurements and pathway enrichment analyses, it was revealed that some DEmiRNAs from the gonad samples involved in sexual differentiation and development (such as cli-miR-210-3p and cli-miR-214-3p) could down-regulate AR (androgen receptor). Cli-miR-181b-5p, cli-miR-9622-3p and cli-miR-145-5p were highly expressed in both the ovaries and testes, which could co-target HOXC9, and were related to regulation of primary metabolic processes. KEGG enrichment analysis showed that DEmiRNAs may play biological and sex-related roles in pigeon gonads. 4. The expression profiles of testicular and ovarian miRNA in adult pigeon gonads are presented for the first time, and the findings may contribute to a better understanding of gonadal expression in poultry.

Rotavirus A Associated with Clinical Disease and Hepatic Necrosis in California Pigeons (Columba livia domestica).

Retrospective analysis of pigeon necropsy submissions to the California Animal Health and Food Safety Laboratory System from 2000 to 2018 revealed 14 submissions diagnosed with rotavirus A hepatic necrosis or "reoviruslike" viral hepatitis. Nine of the 14 submissions (64%) occurred in 2018. Submissions were racing pigeons and squab breeders from flocks with increased mortality. Juvenile and adult pigeons were submitted with a history of depression, diarrhea, regurgitation, labored breathing, and weakness. Flock morbidity peaked at 80% and mortality at 28%. The most consistent findings on postmortem examination were variably congested, mottled, and enlarged livers and spleens. Microscopically, mild to severe hepatic necrosis was observed with variable bile duct hyperplasia, sinusoidal congestion, hemosiderosis, and portal lymphoplasmacytic inflammation. Rotavirus A was detected in hepatocytes and inflammatory cells by immunohistochemistry. Negative-stain electron microscopy identified viral particles consistent with a member of Reoviridae in all negatively stained liver homogenates. Eleven cases were analyzed by reverse transcriptase-PCR targeting rotavirus A viral protein (VP) 6 and VP7 genes. Subsequent phylogenetic analysis of the VP6 and VP7 sequences compared to published Chinese, Nigerian, and German rotavirus A VP6 and VP7 sequences demonstrated the formation of two and three distinct clades, respectively. To the authors' knowledge, rotavirus A hepatic necrosis in pigeons has not been previously reported in the United States and represents a significant emerging disease for the pigeon industry due to the potential for high flock mortality and lost production.

Movement patterns of adult Interior Band-tailed Pigeons (Patagioenas fasciata) in New Mexico

ABSTRACT Improved knowledge of movements of the Interior population of Band-tailed Pigeons (Patagioenas fasciata) is needed to inform management decisions. We investigated daily and seasonal moveme...

Intraocular Pressure Measurement by Rebound Tonometry (TonoVet) in Normal Pigeons (Columba livia).

We evaluated the applicability of a rebound tonometer (TonoVet) in pigeon eyes and established normal reference intraocular pressure (IOP) values in healthy pigeons; 20 eyes of euthanized pigeons were used for calibration of the TonoVet and 48 eyes of 24 adult pigeons were used for measurement of reference IOP. First, IOP of pigeon eyes ex vivo were measured using the 'd' and the 'p' modes of the TonoVet and compared to manometric IOP values from 5 to 80 mm Hg. Then, to establish normal reference values, IOP was measured from clinically normal pigeons in vivo. The 'd' and the 'p' modes of the TonoVet showed a strong linear correlation with the manometric IOP (R2 = .996 and .991, respectively). The obtained regression formulas were: y1 = 0.439x + 2.059 and y2 = 0.330x - 0.673, respectively (y1, 'd' mode of TonoVet; y2, 'p' mode of TonoVet; x, manometric IOP). The 'd' and the 'p' modes consistently measured one-half and one-third of the actual IOP, respectively. Therefore, the formula obtained through the 'd' mode was applied to obtain reference values. The calibrated IOP of normal pigeon eyes was 19.5 ± 4.4 mm Hg. The actual IOP could be calculated using the presented formula. Considering the limitations of the 'p' mode, use of the 'd' mode is more appropriate. Therefore, the TonoVet rebound tonometry under the 'd' mode is a reliable method for measuring IOP in pigeons.

Comparison of Viremia, Cloacal Virus Shedding, Antibody Responses and Pathological Lesions in Adult Chickens, Quails, and Pigeons Infected with ALV-A

Subgroup A of the avian leukosis virus (ALV-A) can cause severe pathological lesions and death in infected chickens, and its reported hosts have increased recently. To assess the susceptibility of adult chickens, quails, and pigeons to ALV-A, three sets of 250-day-old birds were intraperitoneally inoculated with ALV-A. Viremia and cloacal virus shedding were dynamically detected using an immunofluorescence assay (IFA), ALV-P27 antigen ELISA or RT-PCR; pathological lesions were assessed using tissue sections; ALV-A in tissues was detected by IFA; and ALV-A antibody responses were detected using antibody ELISA kits and an immune diffusion test. The results indicated that persistent viremia occurred in 80% (8/10) of infected chickens, and transient viremia occurred in 17% (2/12) of infected quails, but no viremia occurred in infected pigeons. Cloacal virus shedding occurred intermittently in 80% (8/10) of infected chickens and in 8% (1/12) of infected quails but did not occur in infected pigeons. Severe inflammatory pathological lesions occurred in the visceral tissues of most infected chickens, and mild lesions occurred in a few of the infected quails, but no pathological lesions occurred in the infected pigeons. The ALV-A virus was detected in the visceral tissues of most infected chickens but not in the infected quails and pigeons. Obviously different ALV-A antibody responses occurred in the infected chickens, quails and pigeons. It can be concluded that adult chickens, quails and pigeons have dramatically different susceptibilities to ALV-A. This is the first report on artificial infection by ALV-A in different birds.

Aging is associated with larger brain mass and volume in homing pigeons (Columba livia)

In mammals, the brain decreases in mass and volume as a function of age. The current study is, to the best of our knowledge, the first to investigate age-related changes in brain mass and volume in birds. Following perfusion, brains from young and old homing pigeons were weighed on a balance and orthogonal measurements of the telencephalon, cerebellum, and tecta were obtained with a digital caliper. It was found that older pigeons had heavier brains than younger pigeons, a difference that remained after controlling for body mass. Additionally, older pigeons had on average greater estimated telencephalon volumes than younger pigeons, again also after controlling for body mass. Cerebellum and right tectum volumes also differed between age groups after controlling for body mass, with older pigeons having a larger cerebellum and right tectum than younger pigeons. In sum, brains are on average heavier and larger in old pigeons, which display age-related cognitive decline, compared to young adult pigeons. The larger brain in older homing pigeons also lies in stark contrast with aging of the mammalian brain.

Histomorphological and Histochemical Study of the Healthy Liver and Pancreas of Local Adult Homing Pigeon (Columba Livia Domestica)

The purpose of this study was to describe, some the grossly and histological structures and histochemical features of the liver and pancreas of local adult homing pigeon. The present study was conducted on 20 local adult homing pigeon divided into two groups (10 for morphological study and 10 for histological and histochemical study). The morphological results showed that the liver located in the right and left hepatoperitoneal cavity, it has red-brown to dark brown in color, the weight of the liver was (1.59 ± 0.21%) in relation with the body weight. The liver is divided into two undivided lobes left and right, the right lobe is larger than left lobe, mean length, weight and thickness of wall of left and right lobes were (32.1 ± 0.41mm), (22.6 ± 0.23 gm). and (3.5 ± 0.02 mm); (43.7 ± 0.25 mm), (46.6 ± 0.16 gm), (4.2 ± 0.03 mm) respectively. the pancreas was long gland, is on the lower right side of the abdominal wall between the arms of the duodenum. The mean length and weight of pancreas was (97.5 ± 2.20 mm), (3.12 ± 0.26 gm) respectively. Histological examination revealed that the liver consist of several lobules separated from each other by thin trabeculae of connective tissue extend from delicate capsule that enclosed the liver. The basic unit of the parenchyma of liver is hepatocyte which arranged in plates or cords like that radiated around the central vein and between these cords there is sinusoids lined by a layer of fenestrated endothelial cells and Kupffer's cells. In the boundary of each lobule showed portal area which consist of hepatic artery; hepatic vein and bile duct lining by cuboidal cells. The mean thickness of capsule, diameter of central vein, portal vein, hepatic artery and hepatic duct were (145 ± 12.6, 624 ± 32.4, 523 ± 90.0, 190 ± 20.4 and 325 ± 12.1 μm) respectively. The pancreas was serous tubuloacinar gland which covered by a thin connective tissue capsule consisted of collagenous, elastic and reticular fibers. The mean it thickness was (47 ± 2.2) μm. The parenchyma was consisted of exocrine portion and pancreatic islands. The pancreatic islands were composed of large Alpha and small Beta islets. The duct system composed of intercalated duct, intralobular duct, interlobular duct and main excretory duct. The histochemical study the hepatic cells were positive to periodic acid Schiff stain. The pancreatic islands were composed of large Alpha and small Beta islets.

Determination of the pharmacokinetics of a single oral dose of trazodone and its effect on the activity level of domestic pigeons (Columba livia).

To determine the pharmacokinetics of a single oral dose of trazodone and its effect on the activity of domestic pigeons (Columba livia). 6 healthy adult male domestic pigeons. During the first of 3 experiments, birds received orally administered trazodone at doses ranging from 3 to 30 mg/kg to determine the dose for subsequent experiments. During the second experiment, each bird received 1 dose of trazodone (30 mg/kg, PO). Blood was collected for determination of plasma trazodone concentration before and at predetermined times for 24 hours after drug administration. Pharmacokinetic parameters were calculated by noncompartmental analysis. During experiment 3, birds were instrumented with ultralightweight accelerometers and received orally administered trazodone (30 mg/kg) or an equal volume of water twice at a 48-hour interval. Activity of birds was monitored for 24 hours after administration of each treatment. No adverse effects were observed. Mean ± SD terminal half-life of trazodone was 5.65 ± 1.75 hours. Plasma trazodone concentrations remained > 0.130 μg/mL for approximately 20 hours. Trazodone did not affect the activity of birds during the first 2 and 15 hours after administration. Results suggested that oral administration of 1 dose (30 mg/kg) of trazodone to healthy pigeons was safe and resulted in plasma drug concentrations that were similar to those considered therapeutic in humans and dogs for up to 20 hours. Further research is necessary to characterize the pharmacokinetics for repeated doses as well as the clinical effects of trazodone in birds with behavior problems.

Effect of Photoperiod on the Egg Production, Plasma Luteinizing Hormone, Follicle-Stimulating Hormone, Gonadal Hormones, and Mrna Levels of Lh and Fsh in the Hypothalamic-Pituitary-Gonadal Axis of Pigeons

ABSTRACT We investigated the egg production, changes in luteinizing hormone (LH), follicle-stimulating hormone (FSH), gonadal hormones, and their mRNA levels in the hypothalamic-pituitary-gonadal axis of White King pigeons submitted to different photoperiods. The treatments consisted of three photoperiods (8 h light (L):16 h dark (D), 12L:12D, and 16L:8D), with three replicates of twelve pairs of adult pigeons. The birds were exposed the photoperiods for 45 days. Egg production performance was recorded daily. Six pigeon pairs per replicate were selected for plasma collection, and six pigeon pairs per replicate for the resection of the hypothalamic-pituitary-gonadal (HPG) axis. Egg production was significantly improved by long-day lighting (16L:8D), while no differences in egg shape index were detected. Higher average egg weight was obtained in 16L:8D group, whereas broken egg percentage was higher in the 8L:16D group. Female LH level was significantly higher in long-day lighting, and the FSH level significantly lower in short-day lighting. The females in the 16L:8D group had higher estrogen level. The photoperiods had a minor effect on plasma LH and testosterone in males, whereas the FSH level was significantly higher in the 16L:8D group. The level of LH mRNA expression was higher in both females and males of the 16L:8D group. Similar trends in FSH mRNA expression observed in both females and males. The 16L:8D photoperiod not only improved egg production, but also stimulated plasma LH, FSH, gonadal hormones, and promoted LH and FSH mRNA expression in pigeons.

Effect of monochromatic lights on egg production, sex hormone levels, and expression of their receptors in pigeons

This study evaluated the effects of monochromatic light on egg production, egg weight, fertility rate, plasma sex hormone levels, and their receptor mRNA levels in the HPG axis of pigeons. Sixty paired adult White King pigeons were randomly divided into four groups, exposed to violet light (VL), green light (GL), red light (RL), or white light (WL). Exposure to monochromatic light comprised 16 h of light, every 24 h for 100 days. Nine paired pigeons from each group were selected for estradiol (E2) and testosterone (T) analysis, and 24 paired birds were randomly selected from the four groups for ERβ and AR expression analysis. Results showed that RL increased egg production more than WL and VL (P < 0.05). No significant difference was observed in egg weight or fertility rate of birds exposed to monochromatic light (P > 0.05). Plasma E2 in female pigeons exposed to RL was higher than that in those exposed to VL (P < 0.05). No significant difference was noted in plasma T levels in male pigeons (P > 0.05). In females, GL increased ERβ mRNA levels in the pituitary (P < 0.05), and RL significantly increased ERβ expression in the ovary (P < 0.01). In males, RL induced the highest AR mRNA levels, and WL induced the lowest levels in the pituitary and testis (P < 0.01). In conclusion, the results suggest that RL improves egg production, and enhances E2 concentration, ERβ expression in the ovary, and AR expression in the pituitary and testis.