Early Sexual Maturation Research Articles

Reproductive characteristics of indigenous village chickens

BackgroundIndigenous village chickens (IVCs) show a wide variation in production performance and reproductive characteristics. This high variation is occurred due to genetic and environmental factors and gene-environment interactions.ResultsThis work reports the results of a cross-sectional study conducted using a face-to-face interview with 119 small-scale farmers regarding their insights on the production performance and reproductive characteristics of IVCs. It was reported that pullets were sexually mature on average at the age of 5.5 months and cockerels at 6 months. This comparatively early sexual maturity by the standards of IVCs might be associated with the impact of uncontrolled gene flow from production breeds. However, there is high variation in age at sexual maturity at an individual bird’s level. It was found that pullets mature earlier than cockerels (t = 3.250, df = 159, p = 0.001, 95% CI: -0.670, -0.166). According to the respondents, local hens laid on average 14 eggs per clutch. The average number of clutches per year was 4, which can culminate in the yearly production of 56 eggs. A significantly large proportion of the respondents reported that the dry season is appropriate for laying eggs (96.7%) and brooding chicks (94.1%). During the dry season, the scavenging feed resource is relatively abundant, the risk of infection is comparatively low, and the hot weather is suitable for laying eggs and brooding chicks. IVCs possess a long reproductive lifetime, that is, on average, 3 years in hens and 2 years in cocks, which makes them more productive than has been anticipated. For example, this study found that a hen, on average, can lay 174 eggs and hatch 58 chicks in its average reproductive lifetime of 3 years.ConclusionsThe high intrapopulation variation in the reproductive performance of IVCs is vital resource in genetic improvement programs.

Analysis of the genetic diversity of Tahe red deer and population structure of Cervus elaphu/hanglu/canadensis

The Tahe red deer is currently the largest breeding population of antlered Cervus elaphus in China. It has unique characteristics such as drought and roughage tolerance, high antler yield and early sexual maturity. It is a high-quality provenance for cultivating high-yield Cervus elaphus breeds and is also the subject of study on the origin, evolution, and classification of Cervus elaphus. The breeding quantity of Tahe red deer has decreased significantly in recent years due to the influence of feeding conditions and consumer market. This has resulted in a serious threat to its genetic resources. To provide a scientific theoretical basis for the protection of the Tahe red deer population, we performed PCR amplification and direct sequencing of the AMELY2, DBY and SRY genes of the Y chromosome, and the ND1, COX1, ATP6, ND5, Cyt b and D-loop regions of the mtDNA, and analysed their genetic diversity and population genetic structure. The results showed high haplotype diversity and low nucleotide diversity in both the Y chromosome and mtDNA genes. The phylogenetic tree and haplotype network diagram, constructed using white-lipped deer as the outgroup, indicate that Tahe red deer has two distinct ancestral types. The phylogenetic tree, based on the Cyt b gene and D-loop region, reveals that the Cervus elaphus/hanglu/canadensis is divided into three clades: western, central, and eastern. Tahe red deer, C.h.bactrianus, and C.h.hanglu are clustered in the central clade. The study results indicate that Tahe red deer has low genetic diversity and two distinct ancestor types. It is speculated that the central clade is either the earliest differentiation from the ancestor species or the closest to it.

Perlindungan Hukum Terhadap Anak Korban Eksploitasi Seksual Melalui Media Video Call

Children are the embryo of the birth of a new generation which is the successor to the ideals of the nation's struggle and human resources for national development. Children are national assets, the future of the nation and state in the future is in the hands of children now. "The better the child's personality now, the better the future life of the nation will be. Likewise, if the child's personality is bad, the future life of the nation will be bad. Crimes against decency in general raise concern, especially parents' anxiety for female children because apart from being able to threaten the safety of female children (for example rape, obscene acts) they can also affect the process of growth towards earlier sexual maturity. This research discusses 2 ( two) things, namely the urgency of anti-sexual crime education in tackling sexual crimes against children and legal protection for children who are victims of sexual crimes. A brief conclusion can be drawn from this discussion, namely that sexual education/anti-sexual crimes are very important and necessary to introduce every child to know and understand which parts of the body organs should not be touched by other people. Apart from that, legal protection for children as victims has been accommodated in several laws and regulations, especially in Law Number 35 of 2014 Jo. Law Number 23 of 2002 concerning Child Protection.

Effect of feed with extruded components and phytobiotics on quail

Quails are a valuable type of poultry, as their eggs and meat have high nutritional value. Moreover, quails are distinguished by early sexual maturity, high egg production and small body size. These unique characteristics make them an attractive object for breeding and scientific research. The purpose of the study was to investigate the effect of feed with extruded components and phytobiotics on the meat productivity and blood biochemistry of Texas quails. The methodology involved dividing 200 quails into experimental and control groups, feeding them different diets over a 60-day period, and analysing their growth performance, meat yield, and biochemical blood parameters using statistical analysis tools. As a result of the research, it was revealed that feed produced according to the developed recipe has a positive effect on the weight gain of quails. In the experimental group (EG), the absolute increase was 313.7 ± 4.34 g, in the control group (CG) – 275.9 ± 2.89 g (not significant difference, P > 0.05). Furthermore, the feed with extruded components and phytobiotics led to improved feed conversion ratio in the EG compared to the control. The birds in the EG also demonstrated higher carcass weight and yield. The experimental diet also appeared to have a positive influence on the immune status of the quails. The results demonstrate the potential benefits of incorporating extruded components and phytobiotics into quail feed to improve growth performance and maintain healthy physiological parameters. Evaluating the biochemical blood test results, it can be indicated that no significant changes in the blood composition were detected, which may indicate the absence of a negative effect of the developed feed on the body of birds. The results obtained may be of practical importance for developing optimal diets for meat quails and improving the quality and safety of their products

Single-Nucleus RNA-Seq Reveals Spermatogonial Stem Cell Developmental Pattern in Shaziling Pigs.

Normal testicular development ensures the process of spermatogenesis, which is a complex biological process. The sustained high productivity of spermatogenesis throughout life is predominantly attributable to the constant proliferation and differentiation of spermatogonial stem cells (SSCs). The self-renewal and differentiation processes of SSCs are strictly regulated by the SSC niche. Therefore, understanding the developmental pattern of SSCs is crucial for spermatogenesis. The Shaziling pig is a medium-sized indigenous pig breed originating from central China. It is renowned for its superior meat quality and early male sexual maturity. The spermatogenic ability of the boars is of great economic importance to the pig industry. To investigate testicular development, particularly the pattern of SSC development in Shaziling pigs, we used single-cell transcriptomics to identify gene expression patterns in 82,027 individual cells from nine Shaziling pig testes at three key postnatal developmental stages. We generated an unbiased cell developmental atlas of Shaziling pig testicular tissues. We elucidated the complex processes involved in the development of SSCs within their niche in the Shaziling pig. Specifically, we identified potential marker genes and cellular signaling pathways that regulate SSC self-renewal and maintenance. Additionally, we proposed potential novel marker genes for SSCs that could be used for SSC isolation and sorting in Shaziling pigs. Furthermore, by immunofluorescence staining of testicular tissues of different developmental ages using marker proteins (UCHL1 and KIT), the developmental pattern of the spermatogonia of Shaziling pigs was intensively studied. Our research enhances the comprehension of the development of SSCs and provides a valuable reference for breeding Shaziling pigs.

Isolation, culture, characterization and the functional study of testicular Leydig cells from Hezuo pig.

Testosterone, an important sex hormone, regulates sexual maturation, testicular development, spermatogenesis and the maintenance of secondary sexual characteristics in males. Testicular Leydig cells are the primary source of testosterone production in the body. Hezuo pigs, native to the southern part of Gansu, China, are characterized by early sexual maturity, strong disease resistance and roughage tolerance. This study employed type IV collagenase digestion combined with cell sieve filtration to isolate and purify Leydig cells from the testicular tissue of 1-month-old Hezuo pigs. We also preliminarily investigated the functions of these cells. The results indicated that the purity of the isolated and purified Leydig cells was as high as 95%. Immunofluorescence analysis demonstrated that the isolated cells specifically expressed the 3β-hydroxysteroid dehydrogenase antibody. Enzyme-linked immunosorbent assay results showed that the testosterone secretion of the Leydig cells cultured invitro (generations 5-9) ranged between 1.29-1.67 ng/mL. Additionally, the content of the cellular autophagy signature protein microtubule-associated protein 1 light chain 3 was measured at 230-280 pg/mL. Through this study, we established an invitro system for the isolation, purification and characterization of testicular Leydig cells from 1-month-old Hezuo pigs, providing a reference for exploring the molecular mechanism behind precocious puberty in Hezuo pigs.

Association of obesity and menarche SNPs and interaction with environmental factors on precocious puberty.

Obesity is an important cause for the precocious or early puberty. However, the association between obesity-related loci and the risk of precocious puberty as well as the effect of gene-environment interaction are unclear, especially in the Chinese children population. This was a case-control study using baseline data from two cohorts and hospital cases in China. 15 SNPs loci and several environmental factors were included in the analysis of 1201 participants. Chi-square test and logistic regression were used to analyze the association between SNPs and precocious puberty. Additionally, exploratory factor analysis was conducted on 13 environmental variables, and then to explore their interaction with genes on precocious puberty. The effect allele C of rs571312, and G of rs12970134MC4R were associated with precocious puberty in girls with obesity. Regarding the gene-environment interaction, we found that when girls were in the high socioeconomic status, the rs571312 (OR: 3.996; 95% CI: 1.694-9.423) and rs12970134 (OR: 3.529; 95% CI: 1.452-8.573) risk genotypes had a greater effect on precocious puberty. The obesity risk gene polymorphisms MC4R rs571312 and rs12970134 were associated with precocious puberty in Chinese girls with obesity, and girls with risk genotypes and high socioeconomic status should be given extra attention. This is the first study that identified the association between rs571312 and rs12970134 of MC4R gene and precocious puberty in Chinese children. We found that when girls were in the high socioeconomic status, the risk genotypes of rs571312 and rs12970134 had a greater effect on precocious puberty. The results of this study have great public health implications. It is recommended that girls who are in high socioeconomic status and have a high genetic risk for early sexual maturity should closely monitor their pubertal development and consider early intervention strategies.

Оценка на живото тегло и вълнодайната продуктивност на овце от Карнобатска тънкорунна порода

In order to evaluate the levels of some main productive traits in sheep of the Karnobat Fine Fleece breed, raised in the flock of the Institute of Agriculture - Karnobat, a study was conducted for the live weight and wool productivity of animals born in the period 2013 - 2019. Some main productive traits of 316 sheep were controlled: live weight from weaning to 4.5 years of age, wool yield and staple length up to 4.5 years of age, clean wool yield and clean fiber at 1.5 and 2.5 years. It was established that the sheep of the Karnobat Fine Fleece breed at 2.5 years weigh an average of 59,090 kg live weight and give an average of 6,540 kg of wool with an average staple length of 11.43 cm, an average clean wool yield of 64.42 % and clean fiber – 4,220. The levels of all studied productive traits depended on environmental factors and the year of birth had a significant effect. Linear affiliation gave a significant effect on wool yield and the amount of clean fiber obtained by sheep at 2.5 years. The results obtained for the wool productivity traits are higher than the breed standards and show a good evenness in the flock and by ages. Live weight data are within the norm and confirm the early sexual maturity of the Karnobat fine fleece sheep breed.

Smoltification, seawater performance, and maturation in Atlantic salmon (Salmo salar) fed different fat levels

IntroductionThe use of recirculating aquaculture systems (RAS) to produce Atlantic salmon smolts has resulted in exceptionally high fish growth rates. However, there are potential negative trade-offs between fast growth and key physiological processes, such as inadequate smoltification and early sexual maturation, which can both be linked to body energy reserves.MethodsThis study determined the effect of i) dietary fat levels on Atlantic salmon whole-body fat and fatty acids composition, growth performance and smoltification and ii) a previous dietary regime on seawater growth performance and male early sexual maturation. In freshwater RAS, salmon parr (~19g) were fed 3 fat levels (20, 24, and 28%) over a 14-week period at 12°C. Subsequently, in seawater flow-through systems, smolt (~96g) were fed a control diet (26%) for 12 weeks at 2 temperatures (12 and 16°C).ResultsDietary fat levels resulted in differences in k-factor, fish whole-body fat and fatty acids composition; the low fat diet resulted in fish with a 23% lower whole-body fat when compared to the other two dietary groups at the end of the freshwater phase. These differences in whole-body fat faded at the end of the seawater phase. During the freshwater phase, all three feeds resulted in a comparable growth performance and smoltification indicator values, including k-factor, gill Na+, K+-ATPase, blood serum chloride and smolt index score. In contrast, water temperature resulted in fish body weight differences, where groups reared at 16°C were larger than those reared at 12°C. Nevertheless, both temperature regimes supported a similar thermal growth coefficient. Smolts grown at 16°C showed a higher level of the sex steroids androstenedione compared to those at 12°C. However, 11-ketotestosterone and testosterone levels did not differ despite a trend for higher levels at 16°C. Furthermore, testis histology at the final sampling indicated that some individuals showed initial signs of maturation (stage 3).DiscussionIn conclusion, varying dietary fat levels (20 - 28%) during the freshwater phase did not influence smoltification or male early sexual maturation during the subsequent grow-out phase. However, a temperature increase from 12 to 16°C resulted in larger fish and appeared to stimulate early male maturation in some fish individuals.

New colonisers drive the increase of the emerging loggerhead turtle nesting in Western Mediterranean

The loggerhead sea turtle (Caretta caretta) is sensitive to climate change and is responding by colonising the Western Mediterranean. To understand the rapid nesting increase in recent years in Spain, we sampled 45 hatchlings from 8 nests between 2016 and 2019. We sequenced a mtDNA D‐loop region, genotyped 2291 SNPs using 2bRAD and collected data on clutch size, hatching success, and incubation duration. We confirmed that the colonisation has a Mediterranean and Atlantic mixed origin and we detected that these nests were laid by different females, except for two nests within the same season. Our results suggest that the recent increase in nesting is due to an increase in the number of colonising individuals rather than females born in the same area returning to breed. We hypothesize that this increase in the number of colonisers results from successful conservation efforts, feminisation of the populations of origin and earlier sexual maturation. However, the percentage of offspring females produced in Spain suggests that future returning individuals will aid to the settlement of the new population. These results allow defining the current status of this colonisation although future efforts are needed to detect remigrants to confirm the establishment of a resident population.

Gradually decreasing daylength after smoltification induced by “winter signal“ reduced sexual maturation in male Atlantic salmon

IntroductionMaturation in seawater-adapted (smoltified) male Atlantic salmon is undesirable yet frequently reported in fish weighing up to 1 kg reared under intensive conditions in land-based facilities. Although the photoperiod regulates both smoltification and maturation, the optimal post-smoltification regimen for the prevention of maturation is unclear.MethodsIn this study, mixed-sex Atlantic salmon weighing 95 g were exposed to three different photoperiod regimes: continuous daylength, gradually decreasing daylength, and short-to-long daylength after the induction of smoltification by the “winter signal” (12 h:12 h light:dark). Fish were maintained under these conditions in triplicate for 18 weeks in a brackish water flow-through system at 12°C and with a salinity of 20 ppt. This initial phase was followed by a grow-out period (1 kg–2.5 kg) in seawater (32-ppt salinity) at 13°C for 11 weeks, with exposure to decreasing daylength. Throughout the 29-week study, body condition, gonad development, and morphological traits were assessed. Additionally, during exposure to brackish water, serum 11-ketotestosterone (11-KT) levels were quantified, and the testes were examined histologically. Upon termination of the study, the maturation rate was determined.ResultsThis study exclusively detected maturation among male salmon. Under continuous light exposure, the number of fish initiating maturity steadily increased from week 8 and continued to increase in the subsequent samplings. In the short-to-long daylength group, a subset of male fish showed elevated 11-KT levels at week 14, although their gonadal development and morphological changes were not evident until week 18. Male fish exposed to decreasing daylength showed no substantial increase in 11-KT levels, although a few fish exhibited advanced gonad development by week 18. At the end of the trial, markedly lower percentages of maturing and fully mature male fish were observed among those fish previously exposed to decreasing daylength. The maturation rates at study termination were 44.4% for the short-to-long daylength group, 29.4% for the continuous daylength group, and 4.3% for the decreasing daylength group.DiscussionThese results show that photoperiod can be utilized to regulate maturation in male Atlantic salmon. In addition, decreasing the photoperiod after smoltification seems to limit early sexual maturation without compromising body size development. Thus, decreasing the photoperiod could be utilized to limit maturation in the production of post-smolt salmon or salmon in land-based facilities.

Aging and growth outside the comfort zone: the case of alien fire-bellied toads in France

Understanding why some small populations succeed while others fail to establish in novel environments has major implications in applied fields such as in situ species conservation and reintroductions. Species introductions outside their native range provide excellent opportunities to address such topic, since invasions usually start with small populations. We studied the life-history strategy of a population of the fire-bellied toad (Bombina bombina) introduced in France, outside the natural range of the species, to estimate its population demographic potential. The introduced population showed a fast life history strategy, with early sexual maturation at 2 years of age, a relatively short life-span (3.1 years in females and 2.3 in males, with a maximum age of 5 years), and survival rates similar to those of populations from its native range. The population presents the characteristics for becoming invasive and might pose a threat to the native yellow-bellied toad (B. variegata) populations nearby through hybridization, competition and as potential vector of pathogens and parasites. Its spread should be closely monitored and additional introductions avoided to limit its potential negative impact.

Relationships among development, growth, body size, reproduction, aging, and longevity - trade-offs and pace-of-life

Relationships of growth, metabolism, reproduction, and body size to the biological process of aging and longevity have been studied for decades and various unifying “theories of aging” have been proposed to account for the observed associations. In general, fast development, early sexual maturation leading to early reproductive effort, as well as production of many offspring, have been linked to shorter lifespans. The relationship of adult body size to longevity includes a remarkable contrast between the positive correlation in comparisons between different species and the negative correlation seen in comparisons of individuals within the same species. We now propose that longevity and presumably also the rate of aging are related to the “pace-of-life.” A slow pace-of-life including slow growth, late sexual maturation, and a small number of offspring, predicts slow aging and long life. The fast pace of life (rapid growth, early sexual maturation, and major reproductive effort) is associated with faster aging and shorter life, presumably due to underlying trade-offs. The proposed relationships between the pace-of-life and longevity apply to both inter- and intra-species comparisons as well as to dietary, genetic, and pharmacological interventions that extend life and to evidence for early life programming of the trajectory of aging. Although available evidence suggests the causality of at least some of these associations, much further work will be needed to verify this interpretation and to identify mechanisms that are responsible.

Sleep deprivation alters pubertal timing in humans and rats: the role of the gut microbiome.

Evidence implied that sleeping duration is associated with the timing of puberty and that sleep deprivation triggers early pubertal onset in adolescents. Sleep deprivation can affect metabolic changes and gut microbiota composition. This study investigated the effects of sleep deprivation on pubertal onset and gut microbiota composition in animal models and a human cohort. This study comprised 459 boys and 959 girls from the Taiwan Pubertal Longitudinal Study. Sleep duration was evaluated using the self-report Pittsburgh Sleep Quality Index questionnaire. Early sexual maturation was defined by pediatric endocrinologist assessments. Mediation analyses were done to examine the association between sleep parameters, obesity, and early sexual maturation. Besides, Sprague Dawley juvenile rats were exposed to 4 weeks of chronic sleep deprivation. Vaginal opening (VO) and preputial separation (PS) were observed every morning to determine pubertal onset in female and male rats. The sleep-deprived juvenile rats in the sleep-deprived-female (SDF) and sleep-deprived-male (SDM) groups experienced delayed VO (mean VO days: 33 days in control; 35 days in SDF; p-value < 0.05) and PS (mean PS days: 42 days in control; 45 days in SDM; p-value < 0.05), respectively. Relative to their non-sleep-deprived counterparts, the sleep-deprived juvenile rats exhibited lower body weight and body fat percentage. Significant differences in relative bacterial abundance at genus levels and decreased fecal short-chain-fatty-acid levels were identified in both the SDF and SDM groups. In the human cohort, insufficient sleep increased the risk of early sexual maturation, particularly in girls (OR, 1.44; 95% CI: 1.09 to 1.89; p-value < 0.01). Insufficient sleep also indirectly affected early sexual maturation in girls, with obesity serving as the mediator. Overall, sleep deprivation altered the timing of puberty in both animal and human models but in different directions. In the rat model, sleep deprivation delayed the pubertal onset in juvenile rats through gut dysbiosis and metabolic changes, leading to a low body weight and body fat percentage. In the human model, sleep deprivation led to fat accumulation, causing obesity in girls, which increased the risk of early puberty.

Research Note: Development and application of specific molecular identity cards for “Yufen 1” H line chickens

The "Yufen 1" H line chicken (YF) has excellent characteristics including early sexual maturity and high egg production, and the conservation of its genetic diversity is the core of the breeding activity. To overcome misrepresented breeds and protect the integrity of the germplasm genetic resources, it is important to develop accurate and convenient methods to identify YF. In this study, whole genome resequencing was performed on the YF population, and bioinformatics analysis was conducted by combining the data from different breeds. Linkage disequilibrium (LD) analysis revealed that YF had the slowest LD-decay rate, suggesting strong natural and artificial selection in its history. Through selective sweep analysis, 1,126 selected regions in YF were identified, which contained 163,661 single nucleotide polymorphisms (SNPs). In particular, 5 specific SNPs (SNP1: Chr2:45509616, SNP2: Chr2:45510792, SNP3: Chr9:13788193, SNP4: Chr9:13795646, SNP5: Chr9:13798154) were found exclusively in the YF population. Subsequently, PCR amplification and Sanger sequencing confirmed the presence of these 5 SNPs in YF. Finally, 4 SNPs (SNP1, SNP2, SNP4, SNP5) were screened and verified using the Kompetitive Allele Specific PCR (KASP) typing technique. These SNPs can be used as specific molecular identity cards (IDs) for YF authentication. The present study is of great significance to ensure sustainable conservation and promotion of YF germplasm resources.

Optimization Model for Captive Breeding of Lake Sheep Based on Space Utilization

Power Lake sheep have excellent characteristics such as fast early growth, early sexual maturity, four-season estrus and can be kept in captivity, etc. It is of great significance to explore the development of appropriate production plans to improve the space utilization of farms in order to increase the annual turnout of lake sheep. In this paper, under the condition of continuous production, in order to determine the reasonable number of breeding rams and basic ewes in the farm and estimate the range of the annualized number of sheep, we used a set of inequalities to depict the breeding cycle of the lake sheep from the spatial and temporal dimensions, and established a model to analyze the number of annualized number of sheep under the condition of deterministic factors, and based on the analytical model, we solved the gap between the number of standard sheep pens and the number of standard sheep pens in the existing one, under the requirement of the farms to have not less than 1500 sheep pens per year. gap in the number of standard sheep pens. On the basis of the above model, taking into account the influence of uncertain factors such as the success rate of mating, the number of lambs delivered and the mortality rate, an optimization algorithm for fluctuating reproduction of lake sheep was adopted to achieve the optimization of the production plan in order to maximize the economic benefits.

Clinical Management and Therapy of Precocious Puberty in the Sapienza University Pediatrics Hospital of Rome, Italy.

Puberty identifies the transition from childhood to adulthood. Precocious puberty is the onset of signs of pubertal development before age eight in girls and before age nine in boys, it has an incidence of 1/5000-1/10,000 with an F:M ratio ranging from 3:1 to 20:1. Precocious puberty can be divided into central, also known as gonadotropin-dependent precocious puberty or true precocious puberty, and peripheral, also recognized as gonadotropin-independent precocious puberty or precocious pseudopuberty. Thus, the main aim of this narrative report is to describe the standard clinical management and therapy of precocious puberty according to the experience and expertise of pediatricians and pediatric endocrinologists at Policlinico Umberto I, Sapienza University of Rome, Italy. In the suspicion of early sexual maturation, it is important to collect information regarding the age of onset, the speed of maturation of secondary sexual features, exposure to exogenous sex steroids and the presence of neurological symptoms. The objective examination, in addition to the evaluation of secondary sexual characteristics, must also include the evaluation of auxological parameters. Initial laboratory investigations should include serum gonadotropin levels (LH and FSH) and serum levels of the sex steroids. Brain MRI should be performed as indicated by the 2009 Consensus Statement in all boys regardless of chronological age and in all girls with onset of pubertal signs before 6 years of age. The gold standard in the treatment of central precocious puberty is represented by GnRH analogs, whereas, as far as peripheral forms are concerned, the triggering cause must be identified and treated. At the moment there are no reliable data establishing the criteria for discontinuation of GnRH analog therapy. However, numerous pieces of evidence suggest that the therapy should be suspended at the physiological age at which puberty occurs.

Physiological role of dietary energy in the sexual maturity: clues of body size, gonad development, and serum biochemical parameters of Chinese indigenous chicken

Sexual maturity is a crucial factor in the formation and development of poultry reproductive capacity. The nutritional status has been confirmed to play an important role in the regulation of sexual maturity. To investigate the effect of dietary energy levels on sexual maturity in chicken, diets with 3 energy levels (group L: 2,573 kcal/kg, group C: 2,836 kcal/kg, group H: 3,122 kcal/kg) were implemented to feed Guangyuan Gray chickens. During this trial, body weight, body size, organ development, sexual maturity, reproductive performance and blood biochemical parameters were monitored. The earlier sexual maturity was observed in group H, as well as a heavier first egg weight, larger interpubic distance and higher total cholesterol (T-CHO) content at sexual maturity. The dietary energy levels had no significant effect on body weight at first egg and egg production at 300 d of age. Although dietary energy levels had a significant effect on body weight, comb length, tibia length and girth, abdominal fat weight, oviduct weight and length, T-CHO, triglyceride (TG) content and estradiol (E2) level during the rearing period. No significant difference of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) level among 3 groups was observed during the trial. The dietary energy levels had effects on mRNA expression of GnRH, estrogen receptor 1 (ESR1), estrogen receptor 2 (ESR2) in hypothalamus, gonadotropin inhibitory hormone receptor (GnIHR) in pituitary and luteinizing hormone receptor (LHR), ESR2 in ovary. The GnIHR/GnRHR ratio in pituitary was higher before sexual maturity and decreased at sexual maturity. The results of correlations analysis found that all the body size, carcass traits, serum biochemical parameters negatively correlated with age at first egg except for interpubic distance and serum blood glucose content. Collectively, dietary energy levels had effects on sexual maturity of chicken, which may be achieved by affecting body weight, gonad development, endocrine and the mRNA expression of genes related to hypothalamus-pituitary-gonad axis. These results further set our understanding of how dietary energy regulates sexual maturity.

Biological characteristics and distribution of the glowbelly Acropoma japonicum, a dominant fish in the Beibu Gulf, China

In the 1990s, a rapid increase in fishing intensity in the Beibu Gulf, disrupted the demersal ecosystem, wherein the dominant species shifted to smaller-sized individuals. Among the smaller-sized species, Acropoma japonicum was the most prominent. We examined the biological characteristics, distribution and environmental factors of this species to better understand its population status and sustained dominance. The dominant body length group was 50–55 mm (18.98%), and the dominant body weight group was 4–5 g (15.69%). The exponent b value was 2.55 for both sexes. The ratio of females to males was 1.33:1. Gonadal maturity was mainly at stages III (20.21%), IV (34.10%) and V (28.27%). Size at first maturity (L50) was 39.40 mm for females and 63.16 mm for males. The mean CPUE and proportion of A. japonicum in the survey catches decreased from 2006 to 2018, but increased thereafter. Redundancy analysis indicated that water depth is the most important factor affecting the species' distribution, followed by bottom water temperature. The overall results indicate that long-term dominance by A. japonicum in the Beibu Gulf is likely attributable to early sexual maturity, a high proportion of females and long reproductive time, as well as a suitable environment in the ecosystem.

Metabolic and transcriptomic response of two juvenile anadromous brook charr (Salvelinus fontinalis) genetic lines towards a chronic thermal stress

Many salmonid species are particularly susceptible to chronic and acute temperature changes caused by global warming. We aimed to study the differences in metabolic and transcriptomic responses of a chronic heat stress on a control and selected (absence of early sexual maturation and growth) line of brook charr Salvelinus fontinalis (Mitchill, 1814). We exposed individuals to different temperatures for 35 days (15, 17, and 19 °C). High temperature reduced the growth rate (in length) and the Fulton condition factor. Both maximal metabolic rate and the aerobic scope were higher in fish reared at 17 °C, while they decreased in fish maintained at 19 °C. The relative gene expression of cytochrome c oxidase was lower at 19 °C than at 15 °C. The relative gene expressions of both liver and gill hsp90 was higher at the highest temperature. The standard metabolic rate, while not affected by temperature, was higher for the control line over the selected line. Only in the control line, the relative expression of catalase and of receptor of insulin-like growth factor-1 increased at 19 °C. Our results showed that the selected line was able to cope more effectively with the oxidative stress caused by the rise in temperature.