Growth Rate Of Chicks Research Articles

Single-cell transcriptomics and tissue metabolomics uncover mechanisms underlying wooden breast disease in broilers

Accompanied by the accelerated growth rate of chickens, the quality of chicken meat has deteriorated in recent years. Wooden breast (WB) is a severe myopathy affecting meat quality, and its pathophysiology depends on gene expression and intercellular interactions of various cell types, which are not yet fully understood. We have performed a comprehensive transcriptomic and metabolomic atlas of chicken WB muscle. Our data showed a significant increase in the number of immune cells, WB muscle displayed a unique cluster of macrophages (cluster 11), distinct from the M1 and M2 macrophages. Regarding the myocytes, the most significant differences were the decrease in cell number and the intensification of fatty deposits. Satellite cells were involved in muscle repair and regeneration producing more collagen. Interestingly, the interaction network in the WB group was weaker compared to that in normal breast muscle. Additionally, we found six key differential metabolites across 22 pathways. When WB occurs, myocytes and endothelial cells undergo apoptosis, macrophages are activated and exert immune functions, satellite cells participate in muscle rebuilding and repair, and the content of metabolites undergoes significant changes. This cell transcriptome profile provides an essential reference for future studies on the development and remodeling of WB.

The effect of feed Supplementation with Cannabis sativa on the Growth rate and Development of Broiler Chicks

This experiment was carried out to study the effect of broiler feed supplementation with dry powdered Cannabis sativa on the growth performance of broiler chicks. A total of 25 day-old broiler chicks of similar weight were randomly divided into five equal groups (1, 2, 3, 4 and 5). Each group having 5 chicks. Dry ground Cannabis sativa powder were added to the feed of groups 2, 3, 4 and 5 at the rate of 0.1%, 0.2%, 0.4% and 0.8% respectively per kg of feed, while group 1 served as control. The studied parameters were body weight, feed intake and feed conversion ratio (FCR). After an experimental period of 28 days, the data were analyzed statistically. It was revealed from the results that feed intake and body weight gain was significantly higher (P<0.05) in group 5 compared to the control. FCR was significantly better in birds of group 5 compared to controls. Return per chick (in Naira) was lower in group 5 compared to group 2, 3 and 4 (P<0.05) due to the high cost of Cannabis sativa. It was concluded from these results that feed supplementation with Cannabis sativa has a remarkable impact on the growth rate and development of broiler chicks but may not be the best of option due to its restriction and cost Keywords: Broilers, Cannabis sativa, Feed intake, Weight gain, FCR.

It is good to be average: Ecological correlates of breeding phenology in an Arctic seabird, Alle alle (Dovekie)

Abstract Recognizing the deviation in an animal’s behavior from a population mean is not only necessary to understand the evolution and stability of the whole system but also to predict the future of a population in a changing environment. Arctic seabirds are expected to exhibit high synchronization in timing of breeding at the population level, due to highly seasonal and harsh environmental conditions. Nevertheless, even in such a highly synchronized system, there are always some earlier and later breeders, and the drivers of inter-pair variation remain largely unknown. Using an 8-year dataset on Alle alle (Dovekie), a small Arctic seabird, we examined potential drivers of breeding phenology. We found that A. alle pairs were quite repeatable in their phenology, and preserved their phenological status, with their chicks hatching consistently before, during, or after the population median date for hatching, despite that the calendar position of the median shifted between years. This would suggest that timing of breeding is associated with some pair characteristics, either via properties of the nest and/or some partner’s traits. However, breeding phenology of the pair was not dependent on nest location, pair bond duration or morphological similarity of the partners. Importantly, timing of breeding was negatively associated with chick growth rate, indicating fitness consequences of phenology. A simulation in our study further suggests that the chance of fledgling survival in the context of predation may be the highest for the chicks that hatched during the peak of the hatching period. While our results suggest that the timing of the breeding is important for the reproductive outcome, further research is required to determine the drivers of the consistent breeding phenology within A. alle pairs.

The Assessment of Mixing Solid Waste from Palm Kernel Cake and Indigofera Zollingeriana as Chicken Feed towards the Free-Range Chicken Growth Rate

The Assessment of Mixing Solid Waste from Palm Kernel Cake and Indigofera Zollingeriana as Chicken Feed towards the Free-Range Chicken Growth Rate

Design and Fabrication of Automatic Temperature Control for Chicken Shade

Design and Fabrication of Automatic Temperature Control for Chicken Shade

Lactiplantibacillus plantarum and Saccharomyces cerevisiae-Fermented Coconut Water Alleviates Dextran Sodium Sulfate-Induced Enteritis in Wenchang Chicken: A Gut Microbiota and Metabolomic Approach.

In order to investigate the potential mechanisms of probiotic-fermented coconut water in treating enteritis, this study conducted a comprehensive analysis of the effects of probiotic intervention on the recovery from Dextran Sodium Sulfate-induced acute enteritis in Wenchang chicks. The analysis encompassed the assessment of growth performance, serum indicators, intestinal tissue structure, and metagenomic and metabolomic profiles of cecal contents in 60 Wenchang chicks subjected to intervention. This approach aimed to elucidate the impact of probiotic intervention on the recovery process from acute enteritis at both the genetic and metabolic levels in the avian model. The results revealed that intervention with Saccharomyces cerevisiae Y301 improved the growth rate of chicks. and intervention with Lactiplantibacillus plantarum MS2c regulated the glycerophospholipid metabolism pathway and reshaped the gut microbiota structure in modeling chicks with acute enteritis, reducing the abundance of potentially pathogenic bacteria from the Alistipes and increasing the abundance of potentially beneficial species from the Christensenellaceae. This intervention resulted in the production of specific gut metabolites, including Gentamicin C and polymyxin B2, recognized for their therapeutic effects on acute enteritis. The combined intervention of S. cerevisiae Y301 and L. plantarum MS2c not only enhanced growth performance but also mitigated intestinal wall damage and increased the abundance of gut metabolites such as gentamicin C and polymyxin B2, thereby mitigating symptoms of enteritis. Furthermore, this combined intervention reduced the levels of serum immune markers, including IL-10, IL-6, TNF-α, IFN-γ, and D-lactic acid, thus mitigating intestinal epithelial cell damage and promoting acute enteritis recovery. This study provides crucial insights into the mechanisms of action of probiotics and probiotic-fermented coconut water in acute enteritis recovery, offering new perspectives for sustainable farming practices for Wenchang chicken.

Transcriptome Sequencing and Mass Spectrometry Reveal Genes Involved in the Non-mendelian Inheritance-Mediated Feather Growth Rate in Chicken

The feather growth rate in chickens included early and late feathering. We attempted to characterize the genes and pathways associated with the feather growth rate in chickens that are not in agreement with Mendelian inheritance. Gene expression profiles in the hair follicle tissues of late-feathering cocks (LC), early-feathering cocks (EC), late-feathering hens (LH), and early-feathering hens (EH) were acquired using RNA sequencing (RNA-seq), mass spectrometry (MS), and quantitative reverse transcription PCR (qRT‑PCR). A total of 188 differentially expressed genes (DEGs) were ascertained in EC vs. LC and 538 DEGs were identified in EH vs. LH. We observed that 14 up-regulated genes and 9 down-regulated genes were screened both in EC vs. LC and EH vs. LH. MS revealed that 41 and 138 differentially expressed proteins (DEPs) were screened out in EC vs. LC and EH vs. LH, respectively. Moreover, these DEGs and DEPs were enriched in multiple feather-related pathways, including JAK-STAT, MAPK, WNT, TGF-β, and calcium signaling pathways. qRT-PCR assay showed that the expression of WNT8A was decreased in LC compared with EC, while ALK and GRM4 expression were significantly up-regulated in EH relative to LH. This study helps to elucidate the potential mechanism of the feather growth rate in chickens that do not conform to genetic law.

Genetic improvement of duration of fertility in chickens and its commercial application for extending insemination intervals

The growth rate of chickens has made remarkable progress in recent decades through continuous breeding efforts. However, this advancement has also led to a decline in fertility among commercially bred chickens. Therefore, it is crucial to understand and improve factors that influence fertility to ensure the continued success of the industry. Here, we conduct a 3-generation selection experiment within 2 purebred female lines, with the aim of increasing the duration of fertility (DF). Duration of fertility refers to the length of time hens remain capable of producing fertilized eggs and is a crucial factor that directly impacts chick output. The results showed that significant genetic progress was achieved in embryo survival rates and the fertility duration day during both the peak and late laying periods. Moreover, after 3 generations of selective breeding, the disparities in embryo survival and chick health rates from setting eggs between 8-d and 5-d insemination intervals in the grandparent stock were significantly reduced. The rates decreased from 1.83% and 2.39 to 0.72% and 0.33%, respectively. Surprisingly, the hatching performances of hens with an 8-d interval were comparable to those hens that had not undergone genetic selection for DF and had a 5-d interval. We further discussed the possibility of extending the insemination interval to 8 d in parent stock for commercial practices. The parental populations exhibited remarkable performance in terms of percentages of embryo survival and healthy chicks from the setting eggs, with rates exceeding 94 and 90%, respectively. Thus, it can be inferred that an extended insemination interval is feasible by genetic selection for DF. These findings will provide valuable insights into the efficacy of genetic selection in enhancing DF and its practical application in commercial breeding programs.

Effects of Dietary Microbial Muramidase on the Growth, Liver Histoarchitecture, Antioxidant Status, and Immunoexpression of Pro-Inflammatory Cytokines in Broiler Chickens.

The impact of microbial muramidase (MMUR) addition to broiler chicken rations was evaluated through growth parameters, liver histoarchitecture, antioxidant status, biochemical analysis, and expression of pro-inflammatory cytokines for 35 days. Four hundred three-day-old chicks (97.68 ± 0.59 g) were distributed to four distinct groups with ten duplicates each (100 chicks/group) consisting of: group 1 (G1): a basal diet without MMUR (control group); G2: a basal diet + 200 mg MMUR kg-1 G3: a basal diet + 400 mg MMUR kg-1; and G4: a basal diet + 600 mg MMUR kg-1. The results showed that the final body weight and total weight gain were increased (p = 0.015) in birds fed with diets supplemented with MMUR at 600 mg kg-1. The feed conversion ratio (FCR) was improved in all treatment groups compared with the control group. Birds fed with a diet supplemented with 600 mg MMUR kg-1 showed the highest body weight gain and improved FCR. The values of thyroxin hormones and growth hormones were increased in all MMUR-supplemented groups. Dietary MMUR increased the activities of antioxidant enzymes (total antioxidant activity, catalase, and superoxide dismutase) and decreased the activity of malondialdehyde (p < 0.05). In addition, it increased the values of interleukin 1 beta and interferon-gamma compared with the control group. Furthermore, dietary MMUR increased the expression of transforming growth factor-beta immunostaining in the liver and spleen tissues. Our results show that supplementing broilers' diets with 600 mg MMUR kg-1 could enhance the chicken growth rate and improve their antioxidant, inflammatory, and anti-inflammatory responses.

Between-year and spatial variation in body condition across the breeding cycle in a pelagic seabird, the Red-billed Tropicbird.

Body condition in pelagic seabirds impacts key fitness-related traits such as reproductive performance and breeding frequency. Regulation of body condition can be especially important for species with long incubation periods and long individual incubation shifts between foraging trips. Here, we show that body condition of adult Red-billed Tropicbirds (Phaethon aethereus) at St Helena Island, South Atlantic Ocean, exhibited considerable variation between years (2013-2017) and between different stages of the breeding cycle. Females took the first incubation shift following egg laying, after which males and females alternated incubation shifts of varying length, ranging from <1 to 12 days. Body condition declined in both sexes during an incubation shift by an average of 22 g (2.83% of starting mass) per day and over the incubation period; mass loss was significantly greater during longer incubation shifts, later within a shift and later in the total incubation period. There was also significant differences in incubation behaviour and body condition between years; in 2015, coinciding with a moderate coastal warming event along the Angolan-Namibian coastlines, adults on average undertook longer incubation shifts than in other years and had lower body condition. This suggests that substantial between-year prey fluctuations in the Angola Benguela upwelling system may influence prey availability, in turn affecting incubation behaviour and regulation of body condition. Adults rearing chicks showed a significant reduction in body condition when chicks showed the fastest rate of growth. Chick growth rates during 2017 from two localities in the Atlantic Ocean: an oceanic (St Helena) versus neritic (Cabo Verde) population were similar, but chicks from St Helena were overall heavier and larger at fledging. Results from this multi-year study highlight that flexibility and adaptability in body condition regulation will be important for populations of threatened species to optimise resources as global climate change increasingly influences prey availability.

Effects of different levels of methionine in pre-starter diets on immunity function and DNA methylation in broilers

The study was carried out to determine the effects of different levels of methionine in Pre-starter diets on PPAR gene expression and immune function of broiler chickens. Methionine (Met) is necessary to achieve a fast growth rate in chickens. A total of 240 Ross 308 broilers were equally assigned to 8 treatments with 3 replicates. The treatments included T1: diet with 20% methionine less than Ross catalog recommendation. T2: Standard diet in accordance with the recommendations of the Ross catalog. T3, T4, T5, T6, T7 and T8: diets with 20, 40, 60, 80, 100 and 120 % methionine more than Ross catalog recommendation. The results showed that there was a significant difference in the expression of PPAR gene with the difference in diet methionine levels in the 8 groups. PPAR controls the expression of several genes involved in the proliferation and differentiation of adipose tissue cells. Gene expression in broiler chickens with methionine deficiency and excess may have compensated for this deficiency and excess in the birds. Also, the results indicated that increasing in the levels of methionine in Pre-starter diets of chickens the antibody production against ND increased significantly (P&lt;0.05). Besides, the antibody production against IBD increased significantly (P&lt;0.05). Furthermore, the antibody production against H9N1 not affected (P&gt;0.05). Studies suggest that dietary protein deficiency reduces the concentration of most amino acids in plasma and compromises the immune system. Totally it is suggested that the high levels of Met in the diet maybe beneficial and it needs more studies.

Effect of dietary vitamin D3 and ultraviolet-B light on the behaviour and growth of broilers challenged with social isolation stress

Within intensive poultry production systems, broilers are reared indoors, at fast growth rates in controlled environments with little access to natural light, which together impacts the expression of natural behaviours. Birds can see into the ultraviolet spectrum and the provision of ultraviolet-B (UVB) light may support the expression of natural behaviour and endogenous synthesis of vitamin D3 (vitD3). Commercially, chickens regularly encounter stressors, and both the environment and diet can influence their response to stressors. This study was designed to compare the impacts of providing dietary vitD3 at 4000 IU/kg (VitD) compared with provision via UVB light on the behaviour of broilers challenged with periodic social isolation stress. One-day-old Ross 308 broiler chicks (n = 192) were randomly allocated to non-isolated (control) and periodically isolated groups and were provided with either, additional dietary vitD3, or UVB light, in a 2 × 2 factorial design. UVB lamps were provided in all pens (12% UVB D3 of 55 cm length, 24-Watt, 280–315 nm wavelength and 28.12 µW/cm2 intensity) but in the VitD treatment, there were filters to remove UVB. Behaviour was recorded from video footage using instantaneous scans measuring the number of birds engaged in each behaviour six times per day on 12 days spread across days 2–39, resulting in 72 scan samples per pen. Body weight was measured weekly and analysed to provide context for understanding the activity of broilers. Body weight was modelled using growth curves and poisson models were used to analyse behaviour, controlling for the number of birds visible in scans. Chickens performed less active behaviour when they had been periodically isolated. Chickens spent more time sitting inactive (and less sitting active) and sleeping when they received UVB light but were not isolated. Sunbathing was lower in isolation treatments compared to controls, but this effect was reduced when they received UVB lighting. The growth rate of chickens was highest in the isolation and VitD treatment and higher for VitD compared to UVB treatments. Higher activity on days 2 and 39 was associated with a lower growth rate. These results indicate some benefits of supplementation of UVB light in terms of observing natural behaviour when chickens are exposed to stressors. However, we did not observe large differences in behaviour in chickens receiving UVB light compared to those provided with VitD. Further research is needed to investigate the benefits and optimal level of UVB light to support the behaviour and welfare of broilers.

Early-life prophylactic antibiotic treatment disturbs the stability of the gut microbiota and increases susceptibility to H9N2 AIV in chicks

BackgroundAntibiotics are widely used for prophylactic therapy and for improving the growth performance of chicken. The problem of bacterial drug resistance caused by antibiotic abuse has previously attracted extensive attention; however, the influence of early-day use of prophylactic antibiotics on the gut microflora and on the disease resistance ability in chicks has not been explored. Here, we comprehensively evaluate the growth performance, gut microbial dynamics, level of antibiotic resistance genes (ARGs) in the gut microbial community, and resistance to H9N2 avian influenza virus (AIV) in chickens following long-term and short-term early-day prophylactic antibiotic treatment.ResultsUnexpectedly, long-term prophylactic enrofloxacin treatment slowed the growth rate of chickens, whereas short-term antibiotics treatments were found to increase the growth rate, but these changes were not statistically significant. Strikingly, expansions of Escherichia-Shigella populations were observed in early-life prophylactic antibiotics-treated groups of chickens, which is in contrast to the general perception that antibiotics should control their pathogenicity in chicks. The gut microbiota composition of chickens treated long term with antibiotics or received early-day antibiotics treatment tend to be more dramatically disturbed compared to the gut microbiome of chickens treated with antibiotics for a short term at a later date, especially after H9N2 AIV infection.ConclusionsOur data provide evidence that early-day and long-term antibiotic treatments have a more adverse effect on the intestinal microbiome of chickens, compared to short-term late age antibiotic treatment. Furthermore, our metagenomic data reveal that both long-term and short-term antibiotic treatment increase the relative abundance of ARGs. Our findings highlight the adverse effects of prophylactic antibiotic treatment and provide a theoretical basis for the cautious administration of antibiotics in food-producing animal management.Ao91n5eHkkQPyDkUXXsk_bVideo

Where have all the petrels gone? Forty years (1978–2020) of Wilson’s Storm Petrel (Oceanites oceanicus) population dynamics at King George Island (Isla 25 de Mayo, Antarctica) in a changing climate

Numerous seabird species are experiencing population declines, and this trend is expected to continue or even accelerate in the future. To understand the effects of environmental change on seabird populations, long-term studies are vital, but rare. Here, we present over four decades (1978–2020) of population dynamic and reproductive performance data of Wilson’s Storm Petrels (Oceanites oceanicus) from King George Island (Isla 25 de Mayo), Antarctica. We determined temporal trends in population size, breeding output, and chick growth rates, and related interannual variation in these variables to various environmental variables. Our study revealed a decline of 90% in population size of Wilson’s Storm Petrels in two colonies, and considerable changes in breeding output and chick growth rates. Temporal changes in breeding demographics were linked to interannual environmental variation, either causing changes in food availability (particularly Antarctic krill, Euphausia superba) or in nest burrow accessibility due to snow blocking the entrance. With the expected rise in air and sea surface temperatures, the predicted increases in precipitation over the Antarctic Peninsula will likely lead to increased snowstorm prevalence. Additionally, the rising temperatures will likely reduce food availability due to reduced sea ice cover in the wintering grounds of Antarctic krill, or by changing phyto- and zooplankton community compositions. The ongoing environmental changes may thus lead to a further population decline, or at the very least will not allow the population to recover. Monitoring the population dynamics of Antarctic seabirds is vital to increase our understanding of climate change-induced changes in polar food webs.

Faster growth and larger size at crèche onset are associated with higher offspring survival in Adélie Penguins

Abstract We conducted the first assessment of Adélie Penguin (Pygoscelis adeliae) chick survival that accounts for imperfect resighting. We found that when chicks are larger in size when they enter the crèche stage (the period when both parents forage at the same time and chicks are left relatively unprotected), they have a higher probability of survival to fledging. We investigated the relationships between growth, crèche timing, and chick survival during one typical year and one year of reduced food availability. Chicks that hatched earlier in the season entered the crèche stage older, and chicks that both grew faster and crèched older entered the crèche at a larger size. These relationships were stronger in the year of reduced food availability. Thus, parents increased their chicks’ chance of fledging if they provided sufficient food for faster growth rates and/or extended the length of the brood-guarding period. Early nest initiation (i.e., early hatching) provided parents with the opportunity to extend the guard period and increase chick survival. However, to extend the guard stage successfully, they must provide larger meals and maintain higher chick growth rates, even if just one parent at a time is foraging, which previous work has shown is not possible for all individuals. We show that the factors governing tradeoffs in chick-rearing behavior of Adélie Penguin parents may vary in accord with environmental conditions, a result from which we can better understand species’ adaptations to environmental changes.

Features of Fractal Conformity and Bioconsolidation in the Early Myogenesis Gene Expression and Their Relationship to the Genetic Diversity of Chicken Breeds.

Elements of fractal analysis are widely used in scientific research, including several biological disciplines. In this study, we hypothesized that chicken breed biodiversity manifests not only at the phenotypic level, but also at the genetic-system level in terms of different profiles of fractal conformity and bioconsolidation in the early myogenesis gene expression. To demonstrate this effect, we developed two mathematical models that describe the fractal nature of the expression of seven key genes in the embryonic breast and thigh muscles in eight breeds of meat, dual purpose, egg and game types. In the first model, we produced breed-specific coefficients of gene expression conformity in each muscle type using the slopes of regression dependencies, as well as an integral myogenesis gene expression index (MGEI). Additionally, breed fractal dimensions and integral myogenesis gene expression fractal dimension index (MGEFDI) were determined. The second gene expression model was based on plotting fractal portraits and calculating indices of fractal bioconsolidation. The bioconsolidation index of myogenesis gene expression correlated with the chick growth rate and nitric oxide (NO) oxidation rate. The proposed fractal models were instrumental in interpreting the genetic diversity of chickens at the level of gene expression for early myogenesis, NO metabolism and the postnatal growth of chicks.

ВОЗМОЖНОСТИ МУЛЬТИЛОКУСНОГО АНАЛИЗА В ОЦЕНКЕ ГЕНЕТИЧЕСКОГО ПОТЕНЦИАЛА ПРОДУКТИВНЫХ КАЧЕСТВ КУР ГЕНОФОНДНЫХ ПОРОД

The article discusses the use of genome-wide analysis of associations of single nucleotide polymorphisms (SNPs) in DNA with growth rate in chickens and other productive traits. The chip technology is considered, which makes it possible to detect SNPs localized in multiple places in the genome. Some examples of the use of mutations in structural genes that determine traits and various aspects of the application of genomic selection are also given.

The growth rate of Black-tailed Gull chicks is negatively related to total mercury of female parents on Kabushima (Kabu Island), Japan

The mercury (Hg) contamination at high concentrations affects the physiological state and behavior of animals, however, the effects of low Hg exposure on avian breeding success and the impact on the growth of chicks that depend on feeding from their parents are unclear. We investigated the effects of maternal Hg concentrations on breeding success in a colony of Black-tailed Gulls (<em>Larus crassirostris</em>) breeding on Kabushima, northeastern Honshu, Japan, in 2018 and 2019. Total Hg concentrations in blood cells in females were 2.48 ug/g dry weight ± 0.55 (1.28–3.28) in 2018 and 2.42 ug/g dry weight ± 0.55 (1.87–3.29) in 2019. In our two-year field study, female parents did not differ in Hg concentrations between two years, but δ15Ns, i.e., the difference in diet, were significantly lower in 2019 than those in 2018. The difference in δ15Ns could be related to difference in fledging success between two years (90% and 40% in 2018 and 2019, respectively). However, the results of this study showed that Hg exposure was not significantly associated with clutch size, hatching success, or nest success in the two years with different diets and was not significantly associated with any reproductive parameters at δ15N. Hg exposure was significantly negatively correlated with chick weight gain (g/day), while blood Hg accumulation in female Black-tailed Gulls was below the threshold for direct effects on breeding success. However, there was no noticeable abnormal behavior when feeding the chicks at their Hg exposure levels, under the current level value. Although the breeding numbers of Black-tailed Gulls are not thought to be declining at colonies around Japan at the moment, Hg contamination may threaten their numbers in the future.

QPCTL Affects the Daily Weight Gain of the F2 Population and Regulates Myogenic Cell Proliferation and Differentiation in Chickens.

Molecular breeding can accelerate the process of animal breeding and improve the breeding efficiency. To date, many Indel molecular markers have been identified in livestock and poultry, but how Indels affect economic traits is not well understood. For molecular breeding, it is crucial to reveal the mechanism of action of Indels and to provide more accurate information. The purpose of this study was to investigate how the 52/224-bp multiallelic Indels of the chicken QPCTL promoter area affect the daily weight gain of chickens and the potential regulatory mechanism of the QPCTL gene. The analysis was conducted by association analysis, qPCR, dual-fluorescence assay and Western blotting. The results showed that Indels in the QPCTL promoter region were significantly associated with the daily weight gain in chickens and that QPCTL expression showed a decreasing trend in embryonic breast muscle tissues. Furthermore, QPCTL expression was significantly higher in breast muscle tissues of the AC genotype than in those of the AB and BB genotypes. Based on the transcriptional activity results, the pGL3-C vector produced more luciferase activity than pGL3-A and pGL3-B. In addition, overexpression of QPCTL promoted chicken primary myoblast (CPM) proliferation and inhibited differentiation. The results of this study suggest that Indels in the promoter region of the QPCTL gene may regulate the proliferation and differentiation of CPMs by affecting the expression of QPCTL, which ultimately affects the growth rate of chickens. These Indels have important value for the molecular breeding of chickens, and QPCTL can be used as a candidate gene to regulate and improve chicken growth and development.

Pre-but not post-meiotic senescence affects sperm quality and reproductive success in the North African houbara bustard

Age-dependent reduction in reproductive success can arise due to multiple factors including a deterioration of reproductive physiology. Senescing males have been shown to produce ejaculates with poor sperm quality, which impinges on male reproductive success. In addition to individual age, gamete age can also affect male reproductive success. Accordingly, variance in male reproductive success can be due to pre-meiotic (referring to individual age) and post-meiotic senescence (sperm age). Here, we tested whether male senescence and sperm cell aging have additive or interactive effects on male reproductive success in a bird with a promiscuous mating system, the North African houbara bustard. To assess the effect of pre-meiotic aging, we compared male reproductive success between two age classes (3-6- and 12–16-year-old). To infer the effect of post-meiotic aging, male ejaculates were collected at three-time intervals following a common initial collection (day 1, 5, and 10). Therefore, day 1 ejaculates are supposed to contain younger sperm than day 5 and 10 ejaculates. Following controlled artificial inseminations, reproductive success was assessed using three fitness-linked traits (hatching success, chick growth rate and survival). In addition to reproductive output, we also assessed whether pre- and post-meiotic aging affected a wide range of sperm and ejaculate traits. In agreement with previous reports, we found that males in the older age class produced less sperm with poorer motility compared to young individuals. However, contrary to the prediction, we found that ejaculates collected at day 5 and 10 tended to have better sperm traits such as motility and velocity. The results on sperm traits were generally mirrored in the effect on reproductive success since young males produced offspring that grew faster and had better survival during the first month of life, and eggs fertilized by sperm collected at day 5 had the highest hatching success. In any of the models, there was evidence for interactive effects of male and sperm age. Overall, these results confirm the role of pre-meiotic aging on male reproductive success. The lack of evidence for sperm aging could come from the experimental design but might also reflect the pattern of mating frequency in a species with a lek-based mating system.