Alterations in gonadotropin, prolactin, androgen and estrogen receptor and steroidogenesis-associated gene expression in gander testes in relation to the annual period.

Physiological mechanisms of seasonal changes in testicular function in birds are not fully elucidated. The balance between androgens and estrogens and testis sensitivity for gonadotropin and gonadal steroids are still unclear. The aim of the study was to examine: (1) the changes in circulating and intra-testicular steroid hormone levels and their relationship; (2) the mRNA expression of testicular gonadotropin, prolactin (PRL), progesterone (P4), androgen, and estrogen receptors, and (3) key steroidogenesis processes-related genes with immunofluorescent localization of aromatase in gander testes during the annual period. Testes from ganders (n = 25) in the first reproduction season were obtained at five breeding stages, i.e., prebreeding (PrB), peak of reproduction (PR), postbreeding (PoB), nonbreeding (NB), and onset of reproduction (OR). Males were kept under breeding conditions. It was found that plasma P4 levels decreased at the PoB and NB stages, whereas intra-testicular P4 was the highest in the NB stage. Intra-testicular estradiol (E2) levels were higher at the PoB and NB stages than the other stages, whereas testosterone (T) levels showed a nearly opposite pattern. The plasma estradiol-to-testosterone ratios were higher at the PrB, PoB and NB stages compared to other stages. The transcript abundances for luteinizing hormone receptor (LHR), PRL receptor (PRLR), estrogen receptor alpha (ERα), and estrogen receptor beta (ERß) also change in testicular tissue during the annual period. Moreover, StAR mRNA expression was upregulated at the PoB and NB stages, and CYP11A1 transcript level was the highest at the PoB stage. Stage-dependent changes in the CYP19A1 mRNA and aromatase protein levels with higher abundances of transcript at PoB and NB stages and protein at the NB stage were observed. Localization and immunofluorescent signal intensity for aromatase also differed in relation to the examined stages. It may be suggested that differential E2 levels, as well as aromatase expression and localization across annual stages are responsible for the seasonal activation/inactivation stages of testis spermatogenesis in domestic ganders. These data strongly suggest a role of aromatase in the control of gander steroidogenesis as changes in this enzyme level are associated with alternation in gonadal steroid hormones. In addition, joint action with others hormones, like PRL and LH, seems to be important in the final effect of seasonal reproduction potential.

Annual changes in cell proliferation and apoptosis and expression of connexin 43 in the testes of domestic seasonal breeding ganders.

Molecular mechanisms of seasonal changes in testicular morphology, histoarchitecture, and functions in birds have not been fully elucidated. The aim of the study was to examine the alternations in cell proliferation and apoptosis, these processes-related gene expressions, and gap junction protein (GJA1gene, connexin 43 protein; Cx43) expression and localization in gander testes during annual stages. Testes from domestic ganders (n = 28) in the first reproduction season were obtained at five stages, i.e., prebreeding (PrB), peak of reproduction (PR), postbreeding (PoB), nonbreeding (NB), and onset of reproduction (OR). Males were kept under controlled breeding conditions. Testicular weight, morphometry, and histology (H&E staining) were evaluated, and the following parameters were tested: (1) number of proliferating (PCNA-positive) and apoptotic (TUNEL-positive) cells; (2) mRNA and protein abundances of PCNA, caspase-3, and Cx43 by qRT-PCR and Western blot, respectively; (3) activity of caspase-3 by fluorometric method; and (4) localization of Cx43 by immunofluoresence. Testicular weight was found to decrease by 4-fold at the NB stage with massive depletion of germ cells concomitantly with a reduction of seminiferous tubule (ST) diameter and ST lumen compared to the PR and OR stages. The number of proliferating germ cells was higher at PrB and PR than at the PoB stage, whereas the number of apoptotic cells was higher at PoB and NB compared to PrB and OR. Thus, proliferation-to-apoptosis ratios were lower in PoB and NB than other stages. Moreover, mRNA expression of PCNA exhibited down regulation in these stages compared to PrB and PR. Stage-dependent changes in the Cx43 mRNA level and in the localization pattern in the ST germinal epithelium were observed. Lower abundances of GJA1 transcript during NB and OR than at PoB the stage and irregular distribution of Cx43 protein located near the lumen of ST primarily at PrB and NB compared to the remaining stages were noted. These results suggested that during gander testis development, function, regression, and recrudescence, the interaction between processes of cell proliferation, apoptosis, and changes in the localization of Cx43 protein in the germinal epithelium occurred. The balance between these processes may determine the final functional activity or inactive stage of the testes connected with weight and histoarchitecture changes.

Research Note: The nutritional value of eggs from native Polish Crested chickens and commercial hybrids that have been stored in various conditions.

The aim of the study was to compare the nutritive value of eggs from Polish Crested chickens (PCr) to that of eggs from commercial hybrid Hy-Line Brown (HLB) and to examine the effect of storage conditions on physical quality parameters. In total, 135 PCr (9 pens) and 75 (5 pens) HLB chickens were kept on litter and fed commercial feed. At laying peak (36 wk), all eggs (n = 66/ genotype) were collected on the same day and divided into 3 groups (n = 20): group I was assessed on the day after laying; group II was analyzed after 28 d of storage in a fridge; group III, after 28 d in storeroom conditions of 19.5 to 20.5°C. For group I, vitamin A and E content (n = 3 samples) and fatty acid (FA) profiles (n = 6 samples) were determined. For all groups, the physical quality parameters of the eggs were assessed. The vitamin E content was higher (P < 0.05) for PCr than HLB. The PUFA n-6 FA content was higher and the amount of MUFA was lower (P < 0.05) for PCr when compared to HLB. All physical parameters changed after storage, with more negative changes recorded for group III than for group II. Concerning egg weight, albumen height, Haugh unit score and the pH of the yolk and albumen, interaction between genotype and storage conditions (P < 0.001 - P < 0.05) was demonstrated. The lightest eggs with the lowest albumen height and the highest pH were recorded from PCr in group III. The lowest Haugh unit score was recorded from HLB eggs stored in the same conditions. Moreover, the eggs of PCr were characterized by a higher (P < 0.001) yolk content and yolk color (P < 0.05), whereas the weight of the yolk and content of albumen were lower (P < 0.001) for HLB. Eggs from PCr that are stored in appropriate conditions could possibly be offered as a niche product.

Determination of Annual Plasma Hormone Levels Associated with Reproduction in Long-Day Breeding Domestic Geese.

This paper examines the dynamics of circulating hormone changes connected with reproduction in geese during the annual period related to gonad morphometry. One hundred geese were examined. The levels of prolactin (PRL), triiodothyronine (T3), thyroxine (T4), testosterone (T), progesterone (P4) and estradiol (E2) were estimated. In both sexes, PRL level patterns fit a quadratic trend with elevations in the post-breeding and the second half of the breeding-laying periods. During these periods, differences in the PRL level between sexes were noted. In ganders, increased PRL levels during the laying period occurred earlier compared to in female geese. Cubic trends for T and E2 in ganders and quadratic for T, P4, and E2 in female geese were observed. PRL was negatively correlated with T in both sexes and with P4 and E2 in female geese. A higher level of T3 and variation in T4 in ganders with a quartic trend in ganders vs. a quadratic in female geese were noted. Patterns of PRL, T, and E2 suggested that the breeding-laying period in ganders may be shorter than in female geese. These findings will be used to explore experimental manipulations of the endocrine axis to increase synchronisation of both sexes.

Targeted differential monochromatic lighting improves broiler breeder reproductive performance.

Light perception in birds is composed of the retina and extraretinal sites, located in the brain. Previous studies indicate that selective photostimulation of the eye decreased reproductive performance, whereas extraretinal photostimulation increases it. Differential photostimulation of the retina and extraretinal sites is based on the retina's sensitivity to green wavelengths and on the red wavelengths' ability to penetrate body tissues. We previously found that short-day exposure to green light within a long-day exposure to red light increases reproductive activity in female turkeys and broiler breeder hens. Furthermore, in a study conducted recently in our laboratory, we found that blue light repressed expression of green light receptor in the retina, which can further enhance reproduction activity in broiler breeders. Here, we examined the "brain activate/eye deactivate" hypothesis on gonadal axis activity and reproductive performance in a broiler breeder flock. Broiler breeder hens and roosters (ROSS 308) were divided into 5 light-treatment groups (controlled rooms with light-emitting diodes [LED] lamps): warm white (control), long-day (14 h) red (630 nm) and short-day (6 h) green (514 nm) (red-green), long-day green and short-day red (green-red), long-day red and short-day blue (456 nm) (red-blue), and long-day blue and short-day red (blue-red). Birds were reared from 20 to 55 wk of age. Eggs were collected daily. Weekly egg production calculated. All eggs were incubated for fertility and hatchability examination. Blood was drawn monthly for plasma analysis. At 35 wk of age (after peak production) and 55 wk of age (end of the experiment), 10 hens from each treatment group were euthanized, and selected tissues and glands were taken for gene expression trials. Providing long-day red light to extraretinal photoreceptors while maintaining retinal photoreceptors on short day with blue or green light significantly improved reproductive activities, manifested by elevated egg production and gonadal axis activity compared with Controls and primary breeder recommendations. Long-day green light reduced reproductive performances. We suggest that targeted photostimulation enhances reproductive and gonadal axis activities in broiler breeders.

The effect of parachlorophenylalanine treatment on the activity of gonadal and lactotrophic axes in native Polish crested chickens stimulated to broodiness.

Brooding behavior, a common characteristic of native breeds of the domestic chicken, is marked by elevated prolactin (PRL) levels, which is necessary for incubation and connected with changes in hypothalamic-pituitary-gonadal axis activity. Evidence indicates the serotoninergic system is a potent modulator of PRL secretion. The objective of this study is to investigate whether blocking serotonin synthesis with parachlorophenylalanine (PCPA) prevents incubation behavior in native Polish crested chickens. In addition, we examined the effect of PCPA on the gene expression of the gonadal and lactotrophic axes. Birds were stimulated to broodiness by artificial eggs in nests. At 34 wk of age (April: spring period), the hens were divided into 2 groups (14 hens in each group): control and PCPA-treated (50 mg/kg BW) group. After 5 wk of treatment, the artificial eggs were removed from the nests. Egg production, incubation activity, and levels of plasma ovarian steroids progesterone (P4), testosterone (T), estradiol (E2), and PRL were examined. At the end of the experiment (45 wk of age, June: summer period), ovarian characteristics and mRNA gene expression of gonadal (gonadotropin-releasing hormone [GnRH] I, luteinizing hormone [LH] ß, follicle-stimulating hormone [FSH] ß) and lactotrophic (vasoactive intestinal peptide [VIP], PRL) axes were measured by quantitative real-time PCR. Incubation activity was observed in the hens of both groups but with lower frequency in PCPA-treated birds. Moreover, the PCPA group had a higher cumulative egg production than the controls. During the first six and 8 wk of the experiment, levels of P4 and E2, respectively, were similar in both groups, but all concentrations increased in the PCPA-treated hens after this period. In addition, increased GnRH-I, LHß, and FSHß and decreased VIP mRNA expression was observed in the PCPA group compared with the controls. There were no differences in PRL mRNA expression, the PRL level, and ovarian morphometry between the 2 groups. These results indicate that blockage of serotonin synthesis by PCPA does not effectively prevent incubation in native Polish crested chickens. However, treatment with PCPA increased gonadal axis activity and improved reproductive performance.

Comparison of carcass traits and meat quality of intensively reared geese from a Polish genetic resource flock to those of commercial hybrids.

The aim of the study was to determine slaughter yield and meat quality of native Zatorska (ZG) goose and compare them to those of commercial hybrid White Koluda® goose (WKG) after fattening in an intensive production system. The experiment was carried out on 500 birds of each group and lasted up to 10 wk of age. The birds were kept on deep litter with access to free range and were fed with the same complete feed mixtures, according to dietary requirements for broiler geese. Body weight, carcass composition, and technological properties of breast and thigh muscles were evaluated (pH24, L*a*b* color, water holding capacity, thermal loss, drip loss, and shear force). In addition, chemical composition of breast and thigh muscles, fatty acid profile of muscle lipids, and amino acids of proteins were determined. The body weight, weight of eviscerated carcass, and dressing percentage of ZG were lower (P < 0.05) than those in WKG. However, breast and thigh muscles of both groups of geese were characterized by similar technological and nutritive values. The differences in meat quality traits concerned only the shear force of breast muscles, with higher values (P < 0.05) for WKG. Moreover, dry matter content in breast muscles of ZG was higher than that in WKG. The effect of goose genotype on the level of oleic acid and monounsaturated fatty acids in breast muscles was shown. Also, the amino acid proportion of meat protein depended on goose breed. Breast muscles of ZG were characterized by higher (P < 0.05) content of some nonessential (Glu, Asp, Ala) and essential amino acids (Val, Thr), and thigh muscles contained less (P < 0.05) Gly, Lys, and Leu and more Pro and Ile than WKG. The present results indicate that the meat of both ZG and WKG broilers showed good technological properties and basic chemical composition and fatty acid profile, and the protein was characterized by high nutritional value. Moreover, the smaller carcasses produced from ZG can better meet the needs of the current market.

Effect of Repeated Gathering and Age on the Quality of Zatorska Goose Feathers.

We investigated a reproductive flock of Zatorska geese. The birds were divided into four groups: three-year-old ganders (n=10), and one-, two-, and three-year-old layers (n=30). Mature feathers were collected from the birds between July and September (i.e., after breeding). Before collection, the feathers and down were evaluated to determine their maturity. The quantitative composition of each sample of feathers was evaluated manually. The evaluated quality traits of the feathers were turbidity of an aqueous extract, acidity, oxygen index number, and fat content. The data were analyzed using the SAS statistical package with multivariate analysis of variance for repeated measures. The weight of feathers collected from all three gatherings was the highest for the three-year-old ganders. In subsequent gatherings, the weight of the collected feathers tended to increase. There was a statistically significant difference in down composition between the first and the subsequent two gatherings in all age-groups of geese. Neither the age nor the gender of the birds had an effect on the quantity of down obtained, which was 80-85 g. The turbidity of the feather extract was lowest for feathers collected in the first gathering. For the layers, the turbidity of the feather extract was lowest in feathers obtained from the one-year-old birds. The feathers ranged from slightly acidic to neutral, with pH values between 5.9 and 7.2. The fat content was lowest in feathers collected in the first gathering (2.4-2.7%), and tended to increase in subsequent gatherings. There was no statistically significant difference in the oxygen index number between individual gatherings, or between the three-years-old layers and the ganders.

Mating activity and sperm penetration assay in prediction of the reproduction potential of domestic goose ganders in a harem system.

In a natural mating system, the sexual behavior of birds has an important role in fertility success. Non-competitive mating system provides special conditions to study gander-goose interactions. Behavioral and physiological data from a domestic geese breeding flock was used to determine interrelationships between mating activity (MA) parameters, sperm penetration assay (SPA), plasma testosterone (T) concentration, and fertility (F). Moreover, variation in the frequency of gander-goose interactions during the intensive breeding period and the diurnal rhythm (short day - 10L:14D) were evaluated. The 2-/3-year-old ganders (n=15) and 1-/3-year-old geese (1♂:4♀) were observed. On the basis of successful copulation (SCop), groups of ganders with low (33.3%), intermediate (40%), and high (26.7%) frequency were categorized. Frequency of SCop was greater in the morning than in the afternoon. For the entire breeding period, SPA results obtained for the low frequency group were less than for the intermediate group. Fertility success for ganders from both low and intermediate groups was similar. There was a lack of association between MA, plasma T concentration, and SPA results. However, SCop was positively correlated with fertility. It is recommended that SCop be considered as a prognostic parameter for monitoring of ganders' reproductive potential. It is recommended that the sexual behavior of ganders be evaluated before the 1200h of the day. The SCop with an average frequency of 0.4-0.8 times during the day light hours appears to be associated with fertility results that are satisfactory for geese husbandry. Additionally, the SPA may be considered for identification of ganders with poor reproductive potential to facilitate the decision of changes in harem social structure during the first half of the breeding season.

Effect of breeding stage and photoperiod on gonadal and serotonergic axes in domestic ganders.

Reduction in reproductive potential of ganders with progress in seasonal breeding is a known problem in commercial geese production. The role of changes in hypothalamic-pituitary-gondal axis and testis functions in this process is not clear. This article presents studies on the hypothalamic (GnRH-I, vasoactive intestinal peptide), pituitary (LHß, prolactin [PRL], PRL receptor [PRLR]), testis (PRLR) axis messenger RNA (mRNA) expression during different stages of the breeding period and photoperiodic conditions. Testis mass; histologic and functional (testosterone [T]) parameters; and plasma concentrations of T, LH, and PRL were evaluated. We collected (six times) samples from 2-year-old ganders (n = 48) maintained in short day (10L:14D) during the period from November to July. Moreover, in the peak of sexual activity (March), an additional group was on exposure (6 weeks) to long day (LD; 16L:8D). During the first half of reproduction (January, March; photosensitive period), GnRH-I (1.9 vs. 0.3 relative quantity [RQ]) and LHß (3.0 vs. 0.7 RQ) mRNA transcript expression and concentrations of T (1.9-2.9 vs. 0.3 ng/mL), LH (13.6-7.4 vs. 0.7 ng/mL) were found to be higher (P < 0.05) than at the end of breeding (July). With progress in breeding, marked elevation (P < 0.05) in PRL (22.0-387.1 ng/mL) concentration related to similar changes in vasoactive intestinal peptide (0.9-3.0 RQ) and PRL mRNA abundance (1.3-11.5 RQ; May, July) was observed. However, testis PRLR mRNA increased (P < 0.05) only at the end of reproduction (1.2 RQ) compared to the peak of sexual activity (0.4 RQ; March). Furthermore, changes in mRNA transcript expression of the lactotrophic axis were accompanied with reduction of testis weight (left: 11.1-5.8 g), spermatogenesis (spermatogenic index: 5.4-3.0), and steroidogenesis (T: 24.8-1.3 ng/g testis), which may suggest their pivotal inhibitory modulation role in the regression of seasonal reproductive activity in ganders. The LD conditions (similar to spring-summer) resulted in earlier peripheral changes in T (0.9 vs. 1.8 ng/mL), LH (1.1 vs. 3.8 ng/mL), and PRL (296.1 vs. 161.2 ng/mL) concentrations than in short day, and this may be related to the advance in the timing of the sexual activity failure observed under natural light regimes. The lack of differences in gonadal and lactotrophic axis mRNA expression after LD treatment suggested a regulation based on the posttranslational mechanisms or modification of transcript or protein.

Breeding period-associated changes in semen quality, concentrations of LH, PRL, gonadal steroid and thyroid hormones in domestic goose ganders (Anser anser f. domesticus).

In flocks of geese fertility decreases in the second half of the breeding season. The reasons for this reduction in reproduction ability are still unclear. This study measured changes in semen quality variables throughout the period of intensive breeding in relation to hormonal concentrations associated with the sexual activity of ganders. Semen was collected (2×/week) from 2-year-old ganders in the period February-June. Standard ejaculation parameters and spermatozoa (spz) membrane integrity after E/N and SYBR-14/PI staining were evaluated. The DNA Fragmentation Index was measured by flow cytometry and sperm quality factors (SQF). The plasma levels of T, E2, P4, LH, PRL, THs in relation to semen parameters were evaluated. In ejaculate collected at the onset of the second half of breeding (April - spring period), a reduction in sperm concentration and % of liveE/N and liveSYBR-14+/PI- spz was shown. At this time, decrease in concentrations of LH and T and increase in PRL were found as well as moderate changes in THs were observed. However, in May a second peak in T and sperm production occurred. The DFI-% was higher in the middle part of breeding. Gonadal steroids concentration were not good prognostic marker of the reproductive potential of ganders. We suggest that a marked decline in LH and T in the spring period indicated the onset of endocrine changes mediated by PRL and THs resulting in progressive regression of testis functions. The lowest SQF in the spring/summer period coincided with the highest PRL suggesting an anti-spermatogenic action of PRL in ganders.

Mating activity of domestic geese ganders (Anser anser f. domesticus) during breeding period in relation to age, testosterone and thyroid hormones.

In breeding geese, natural mating applies. The objective of this study was to determine seasonal- and age-related changes in the sexual activity of ganders. Moreover, T, T4 and T3 plasma levels were evaluated. The study was conducted on 2/3-year-old males (n=15) and 1- or 2/3-year-old females (1♂:4♀). Sexual activity of ganders was characterized through the frequency of: courtship, attempts at and successful copulations and total mating activity (MA). Reproductive results manifested by egg production and fertility were recorded. Laying percentage (January-June) was 37.1 and 28.6% for 1-, and 2/3-year-old geese, respectively. MA was noted before the sexual maturity of females and the T level peak. MA was highest at the onset and during peak production (March) for ganders kept with 1-, and 2/3-year-old geese, respectively. From April to May a decrease in fertility with a reduction of the frequency of copulations was observed. At this time low levels of T were noted. The effect of goose age on the MA was shown, with higher frequency of copulations for ganders kept with 1-year-old geese. We suggest that in the successful seasonal mating in geese, social factors such as the presence of females and female age play an important role. The reduction in fertility during the spring period may be associated with decreases in the efficiency of successive mating sequences. The higher frequency of copulations without affecting fertility, for ganders kept with young geese, may be because of differences in sperm transfer or storage/transport efficiency.

Age effect of broiler breeders on fertility and sperm penetration of the perivitelline layer of the ovum.

The objective of this study was to determine the age effect of a broiler breeder flock on duration of fertility and number of spermatozoa penetrating the perivitelline layer overlying the germinal disc (SP/mm(2) GDIPVL). Moreover, in the second half of the flock's reproductive life, the effect of using ejaculates of young roosters (CA2) in artificial insemination (AI) on the above parameters of fertility was estimated. The commercial flock of broiler breeder hens (n = 100) was inseminated six times from 31 to 62 weeks of age. Additional inseminations, with ejaculates of roosters aged 31 and 36 weeks (CA2), were performed at 56 and 62 weeks of age. AI was performed during two consecutive days (D0 and D1) with an insemination dose of 125 x 10(6) spermatozoa/0.06 ml containing pooled ejaculates. The following parameters were studied: the effective and maximum duration of fertility (De and Dm), percent of fertility on different days after AI (FD10, FD15 and FD20), indices of duration of sperm penetration (DSP, SP < or = 3/GDIPVL), SP/mm(2) GDIPVL in eggs laid on successive days after insemination of hens at different age, and correlations between some fertility indices. Both for De and Dm, the highest values were noted after AI of the layers at 36 weeks of age (14.8 +/- 0.49 and 17.4 +/- 0.46 days, respectively), which were about 2 days longer than at 56 weeks. All fertility indices decreased gradually with age, starting from AI at peak egg production (31-36 weeks of age), while the use of ejaculates from CA2 did not help to increase them significantly. Correlation coefficients between SP/mm(2) GDIPVL and the other fertility indices were positive and highest for eggs laid on D3. It is concluded that high De values can be obtained from broiler breeders in adequate environmental and technological conditions of AI. It is suggested that the age-related decrease in fertility is more pronounced in females, in which the efficiency of sperm storage tubules decreases. The present fertility indices indicate the possibility of lengthening AI intervals, especially at peak egg production.