Male gamete biology shows specific features in birds that contribute to the reproductive strategy of flying animals adapted to highly variable environmental conditions. In this paper, we review the main characteristics of bird sperm, their selection and storage in the highly specialized female oviduct, specific features of polyspermic fertilization, and the consequences of these biological adaptations on semen biotechnology. Among other features, the storage of sperm in specific oviducal glands is a key factor to increase reproductive “freedom” but is also a critical point for the success of semen in vitro storage.

View full abstract

Transplantation of male germ cells into sterilized recipients in chicken opened a new approach for chicken transgenesis as well as for preservation of endangered bird species.
We describe the post transplantation re-population of the recipient seminiferous epithelium up to the production of heterologous sperm in about 50% of transplanted males. However, it is important to precisely identify basic germinal cell populations that trigger renewal cascade of the whole process of the spermatogenesis in the testes of cockerels. Detection of the nuclear DNA content by fluorescence-activated cell sorting (FACS) and expression of specific genes in single cell suspensions of testicular tissues seems to be suitable way for selection of proper cells.
An improvement in the approach to germ cell transplantation between fowl males seems to be remarkably influenced by using an enriched subpopulation of c-Kit positive spermatogonia as well as SSEA-1 positive testicular cells as donor cells.
Other chicken spermatogonia specific gene markers such as gfra, stra 8 or dazl can also be used for basic spermatogonial cells identification. Chicken recombinant GFRA1 receptor protein has been prepared and was used for obtaining mouse specific polyclonal antibodies. The presence of GFRA1 protein on the cell surface was confirmed by mmunocytochemical and immunohistochemical analyses.
Particular identification of cellular and molecular markers unique to the germ cells together with efficient transplantation model will make testicular stem cells an indispensable tool not only for biotechnological application but can also contribute to endangered species preservation programs.

View full abstract

The germ cell lineage is unique as it is the cell lineage that ensures the continuation and the variation of genetic information from one generation to the next. Primordial germ cells are the stem cell precursors of this lineage differentiating into mature spermatozoa and oocytes in the adult. The recent development of cell culture conditions for the extended propagation of chicken primordial germ cells isolated from embryonic blood heralds the emergence of a technology that will have a considerable impact on the management of avian resources, efforts in avian species preservation and transgenic technologies. This review will address what is known of the formation of avian germ cells, the current state of the field, and discuss the prospects that this technology offers for both developmental biology and the preservation of avian germplasm.

View full abstract

Korea is an important geographical location for wintering dabbling ducks. In order to investigate their relationships, 92 ducks from ten breeds were sampled from nine different geographical areas in Korea. Of these, 38 samples are represented as Mallard (Anas platyrhynchos), Spot-billed (Anas poecilorhyncha zonorhyncha) and domestic (Anas platyrhynchos domesticus) ducks. They are very closely related to commercial duck breeds. The partial (746 and 749 bp) mitochondrial DNA (mtDNA) COI (Cytochrome Oxidase I) gene sequences were obtained and 126 SNPs were identified, which belong to 23 haplotypes. Eighty five Anas and ten Aix genus have been used for phylogenetic analysis. Based on the neighbor-joining (NJ) method, duck species used in this study can be well differentiated, except for the three duck breeds, Mallard, Spot-billed and domestic ducks, where most of the individuals belong to haplotype 12. The highest K2P distance, 0.31, was observed in Spot-billed ducks, with a range of 0.07-10.96 between the species. However, there was no correlation between geographic distance (km) and K2P distance (%) between the species. Based on our results, duck species can be discriminated with COI sequences, except for the three closely related breeds, and this can be effectively used for an appropriate conservation program for the wild duck breeds in Korea.

View full abstract

Alaska pollack protein (APP) reduces serum triacylglycerol and body fat accumulation by the enhancement of basal energy expenditure through fast-twitch muscle hypertrophy in rats. However, the effects of APP on brain function have not yet been clarified. In the present study, we investigated the effects of orally administered APP on the brain levels of 3-methoxy-4-hydroxyphenylglycol (MHPG), which is a metabolite of norepinephrine (NE) and can be used as an index of NE activity, in fasting chicks. Fasting stress significantly decreased plasma glucose, uric acid, triacylglycerol, proline and ornithine while MHPG levels in the brain and plasma corticosterone concentration were not affected. APP dose-dependently decreased MHPG level in the diencephalon, telencephalon and optic lobe. Plasma uric acid, alanine, β-alanine, arginine, anserine, aspartate, asparagine, glycine, histidine, isoleucine, leucine, lysine, 1-methylhistidine, 3-methylhisitidine, ornithine, proline, taurine and valine were dose-dependently increased with the increase of APP. It has been reported that some of them are known to centrally reduce the stress-induced behaviors of chicks. These results suggest that orally administered APP could influence brain NE activity through increase in amino acids to protect against stress conditions.

View full abstract

This experiment was conducted to evaluate the effect of coccidial control, dietary mineral density, and coccidial challenge on broiler chick performance. Commercial broiler chicks (1008) were placed across 48 floor pens (21 birds/pen, 6 replications/treatment) on either fresh or seeded bedding. Treatments involved phytase-supplemented diets containing two Ca-NPP levels (0.5% Ca, 0.25% NPP or 0.7% Ca, 0.35% NPP), two coccidiosis control strategies (vaccination or in-feed coccidiostat), and two Eimeria exposures (unchallenged or challenged). On d 11 and 20 body weight (BW) and feed consumption (FC) were recorded for each pen. Five birds/trt were sacrificed and intestinal samples were obtained for visual and microscopic lesion scoring on these days. The left tibia was also collected for the assessment of bone strength.
BW, FC, and bone strength were unaffected (P>0.05) by diet, though coccidiosis control methods had an affect on both body weight gain (BWG) and FC from 0-20d. Coccidiosis challenge led to a decline (P<0.05) in overall BWG. Regardless of treatment, visual and microscopic scoring of the duodenum and ceca showed few differences (P>0.05). The percentage of birds having lesions associated with Eimeria acervulina was increased (P<0.05) on d 20. Overall, the results indicate that bird performance and skeletal strength are not affected by decreased Ca-NPP levels when diets are supplemented with phytase, but a coccidiosis challenge will result in reduced growth performance.

View full abstract

This study was conducted to determine the impacts of two levels of oyster mushroom (Pleurotus ostreatus) powder on productive and carcass traits, humoral immune responses, and blood characteristics of Ross 308 male broiler chicks reared to 42 d of age in comparison with a prebiotic supplement. Two hundred and forty, day-old male broiler chicks (Ross 308) were randomly assigned to one of four treatments with four replicates of 15 chicks based on a completely randomized design. The dietary treatments consisted of the basal diet as control, prebiotic group receiving 1 g/kg A-Max^® (Mannan-oligosaccharides), 10, and 20 g/kg oyster mushroom powder added to the basal diet. The obtained results showed that inclusion of 20 g/kg mushroom powder significantly improved body weight over the starter and grower (P<0.05) while feed efficiency was improved only over the starter (P<0.05) period compared to the control group. Considering the entire experimental period, (1-42 d) birds receiving prebiotic supplemented diets exhibited the highest body weight and lowest feed conversion ratio relative to the other treatments (P<0.05). Carcass yield and internal organs relative weights were not influenced by dietary treatments, but prebiotic supplementation significantly (P<0.05) decreased abdominal fat pad compared to the control group. Newcastle, influenza and sheep red blood cell antibody responses of chicks did not differ significantly at either level of inclusion of supplements. Chicks fed supplemented diets had the lowest serum triglyceride concentration at 42 day (P<0.05) compared to the control chicks, but other biochemical and hematological values tested including protein, albumin, globulin, hig-density lipoprotein, low-density lipoprotein, and total cholesterol, red blood cell, white blood cell, hemoglobin and hematocrit were not markedly affected by treatments. In conclusion the obtained results indicated that oyster mushroom powder at an inclusion level of 20 g/kg of diet had favorable effects on performance criteria of chicks reared to 28 day of age while, prebiotic supplementation revealed its beneficial impact on chicks productive traits at slaughter age, besides reducing carcass abdominal fat and serum triglyceride concentration at 42 day.

View full abstract

Effects of maternal and posthatch dietary oils and vitamin E (VE) on antioxidant capability and muscle quality of the progeny broilers were studied. Two-factor experiment was designed, there were two main effects, one was oil source, the other was VE level, diets were as follows: corn oil (CO) +20 mg/Kg VE, fish oil (FO) +20 mg/Kg VE, CO+ 100 mg/Kg VE and FO+ 100 mg/Kg VE. The results showed that: (1) FO in maternal and posthatch diets significantly reduced body weight of the progeny broilers at 42 d (P<0.05), significantly increased food/gain ratio (P<0.01) of 0-42 d, significantly increased lipid peroxides malondialdehyde (MDA) content of broiler serums at 10 d (P<0.01), 21 d (P<0.01), 28 d (P<0.01) and 42 d (P<0.01) respectively, there was also a substantial interaction (P<0.05) between oil sources and vitamin levels at 28 d, and also a trend at 42 d, the highest MDA content of serums was always observed in FO with 20 mg/kg VE group, the lowest MDA content of serums was occured in CO with 100 mg/kg VE group. (2) FO inclusion in maternal and posthatch diet increased breast meat MDA content, decreased superoxide dismutase (SOD) activity of breast meat compared to corn oil treatment. (3) Addition of higher level of VE in maternal and posthatch diets significantly reduced MDA content of broiler serums at 10 d, 21 d (P<0.05), 28 d (P<0.05) and 42 d (P<0.05) respectively. (4) Higher level of VE in maternal and posthatch diets also significantly reduced drip loss of breast meat of the progeny broilers, but increased meat MDA significantly, decreased meat SOD activity significantly, besides, there was an interaction trend (P=0.06) between oil source and VE level on meat MDA, FO group with higher VE appeared the highest MDA content in breast meast. These findings suggest that diet with FO need more antioxidant to protect from oxidation, but FO oil with higher VE in maternal and posthatch diets may bring about meat deterioration to the progeny broilers.

View full abstract

This study was conducted to evaluate whether culture of chicken fibroblasts could induce cell aggregation leading to embryonic stem cell (ESC)-like, colony-formation. Gradual increase in expression of leukemia inhibitory factor (LIF) gene were detected as retrieval age of chicken embryonic fibroblasts (CEFs) was increased from 5- to 8-day-old, which accompanied increase in cell proliferation after culture in LIF-free medium. Colony-like cell aggregation was detected after culture of the 8-day-old fibroblasts, while the exposure to 0.5, 1 or 2 mM glutathione did not increase the cell aggregation. The cell aggregates were positive for periodic acid Schiff solution, and the antibodies of anti-stage specific embryonic antigen (SSEA)-1 and anti-SSEA-3. However, they were negative for alkaline phosphatase and anti- SSEA-4 antibody. Expression of chicken Vasa homolog did not detect in the aggregated CEFs. Continuous culture of the aggregates in LIF- and CEF monolayer-free condition resulted the formation of embryoid bodies possessing the cells being positive for three germ layer makers (Nestin, S-100, smooth muscle actin, desmin, alpha-fetoprotein and Troma-1). In conclusion, our results demonstrate cell aggregates having ESC-like activity can be derived from the culture of chicken fibroblasts on CEF monolayer, which strongly supports the possibility on deriving chicken stem cells from non-germline tissue.

View full abstract

In a view to explore blood vessels neo formation as a possible adaptive response to hypobaric hypoxia in the chicken lung, mRNA expression of the following genes was examined: hypoxia inducible factor-1α (HIF-1α) and -2α (HIF-2α), vascular endothelial growth factor (VEGF), receptors for VEGF (Flk-1 and Flt-1), hepatocyte growth factor (HGF) and its receptor (HGFR), epidermal growth factor (EGF) and its receptor (EGFR). The molecular regulation of these genes remains completely unknown in these conditions. One group of birds was exposed to relative normoxia and the other group, to hypobaric hypoxia. Comparisons were made among non-pulmonary hypertensive chickens under relative normoxic conditions (NHCN) and non-pulmonary hypertensive chickens (NHCH) and pulmonary hypertensive chickens (PHCH) under hypobaric hypoxic conditions, respectively. For HIF-2α, VEGF, Flk-1, HGF and HGFR genes, no statistical differences were found in the relative mRNA expression between PHCH and NHCH, but those were lower when compared to NHCN (P<0,05). For Flt-1 mRNA expression, a significant difference between NHCH and NHCN was noted (P<0.05), but relative mRNA expression in the lungs of PHCH did not show differences with findings in the lungs of NHCN or NHCH. HIF-1α and EGFR mRNA expression analysis indicated significant differences between NHCN and PHCH, but not between NHCH and PHCH. There was a general trend towards a lower mRNA expression of genes involved in the response to hypoxia and vascular proliferation in the lungs of chickens exposed to chronic hypoxia in PHCH and NHCH when compared with NHCN. These results show consistency with those registered in a parallel study which indicated a lower number of blood vessels with a diameter range ≥50-100 μm in the lungs of PHCH and NHCH when compared with observations obtained in NHCN.

View full abstract

Birds reduce their food intake by the exposure to high ambient temperature (HT) which ultimately affects their productivity. However, physiological and behavioral responses of young chicks of different ages to HT have not yet been investigated. In this study, we examined the effects of HT (40°C, 4-h) in 3-, 5-, 7-, 14- and 21-d old chicks. There were no significant differences in food intake between heat exposed and control chicks up to 7-d old, while clear suppressions of food intake were observed in 14- and 21-d old heat exposed chicks. Body weights were not affected in all age groups; however, rectal temperature was significantly increased in almost all ages. We examined blood metabolites of 7-, 14- and 21-d old chicks and found that plasma glucose concentration gradually increased in 14- to 21-d old heat exposed chicks. Conversely, triacylglycerol age-dependently decreased during exposure to HT. No significant changes were detected in plasma total protein, uric acid and calcium investigated in 7-, 14- and 21-d old heat exposed chicks compared to control groups. However, plasma glutamic-oxalacetic transaminase showed a significant interaction between HT and age, implying that liver and/or heart was damaged by HT with aging. These results indicate that HT (40°C; 4-h) suppresses food intake in young chicks of 14- or 21-d old age which reflects in some of their plasma metabolic concentrations.

View full abstract

Sexual dimorphism of growth and development of organs and tissues in poultry species results from differentiated endocrine system and metabolic processes rate, and leads to difference of skeletal muscles mass and final body weight. Our knowledge on physiological variation in free amino acid status of skeletal muscles in meat-type turkeys is strongly limited. The aim of the study was to determine sex-related differences of free amino acid concentration in breast muscles obtained from turkeys at the age of 20 weeks. The experiment was performed with 34 birds divided into two equal groups consisting of females and males. During whole period of the breeding cycle all birds were kept under identical environmental conditions and had free access to fresh water and feed supplied in accordance to their growth stage. At the age of 20 weeks of life, final body weights of birds were measured and breast muscle samples were obtained. To evaluate free amino acid concentrations in breast muscles, the samples were analyzed with the use of ion-exchange chromatography. Statistical comparison of amino acid concentration in breast muscles of females and males was performed using non-paired Student’s t-test. Final body weight was 27.6% higher in male than in female turkeys. Skeletal muscle concentration of glutamine, tryptophan, serine and asparagine was found to be significantly higher in males than in females, while opposite results were obtained analyzing cysteic acid, taurine and valine. In conclusion this study revealed sex-differentiated final body weight and skeletal muscle amino acid concentrations in turkeys. Improved skeletal muscle metabolism of functional amino acids glutamine and tryptophan in males may be postulated as crucial factors responsible for their higher growth rate and final body weight when compared to females. The obtained results may serve to optimizing feed for turkeys and their systemic development.

View full abstract