Exposure to heat stress can cause a significant increase in the death rate and disease susceptibility of poultry birds, ultimately impacting the profitability of the poultry industry. Despite being a more economical choice, Japanese quails (Coturnix japonica) are not immune to the harmful effects of heat stress. Quails may experience negative effects on their reproductive performance due to excessive reactive molecules caused by heat stress. However, they have developed various mechanisms to maintain their reproductive abilities in such conditions. The neuroendocrine system in birds plays a vital role in regulating their reproductive responses to thermal stress, and it is also connected to other environmental factors such as photoperiod that can impact their reproductive performance. Hormones are crucial in the complex interactions necessary for sexual maturation and reproductive responses to heat stress in Japanese quails living in stressful thermal conditions.

Keel bone damage is an important welfare issue in laying hens and can occur with a high prevalence of up to 100% of hens within one flock. Affected hens suffer from pain. Although multiple factors contribute to the prevalence and severity of keel bone damage, selection for high laying performance appears to play a key role. With up to 300 eggs/year, Japanese quails show a high laying performance, too, and, thus, may also show keel bone damage. However, to our knowledge, there are no scientific results on keel bone damage in Japanese quails to date. Therefore, the aim of this study was to assess whether keel bone fractures and deviations occur in Japanese quails and to obtain more detailed information about the development of their keel bone during the production cycle. A group of 51 female quails were radiographed at 8, 10, 15, 19, and 23 weeks of age. The X-rays were used to detect fractures and deviations and to measure the lateral surface area, length, and radiographic density of the keel bone. In addition, the length of the caudal cartilaginous part of the keel bone was measured to learn more about the progress of ossification. At 23 weeks of age, quails were euthanized and their macerated keel bones assessed for fractures and deviations. Both keel bone deviations and keel bone fractures were detected in the Japanese quails. In the 23rd week of age, 82% of the quails had a deviated keel bone as assessed after maceration. Furthermore, there was a decrease in radiographic density, lateral surface area, and length of the keel bone between weeks of age 8 and 19. This could indicate a general loss of bone substance and/or demineralization of the keel bone. Our study shows that keel bone damage is not only a problem in laying hens but also affects female Japanese quails.

Investigating the impact of early egg production selection (the first 90 d of laying) on egg production features, cumulative selection response (CSR), and the mRNA expression of gonadotropins (FSHβ and LHβ), and their receptors (FSHR and LHR), in Japanese quails was the goal. The selection experiment involved 1293 females in all, 257 from the base group and 1036 from the 4 selected generations. Age and body weight at sexual maturity (ASM, BWSM), weight of the first egg (WFE), days to the first 10 eggs (DF10E), egg mass for the first 10 eggs (EMF10E), egg weight (EW), egg number at the first 90 d of laying (EN90D), and egg mass at the first 90 d of laying (EM90D) were all recorded. Most egg production traits had heritability estimates that were low to moderate and ranged from 0.17 to 0.33., where the highest estimates were reported for EN90D (0.33) and BWSM (0.32). With the exception of EN90D, low to moderate positive genetic correlations were observed between ASM and other egg production traits (0.17-0.44). The fourth generation showed significantly (P < 0.05) lower ASM and DF10E but higher BWSM, WFE, EN90D, EM10E, and EM90D when compared with the base generation. CSR were significant (P < 0.05) for ASM (-6.67 d), BWSM (27.13 g), WFE (0.93 g), DF10E (-1.25 d), EN90D (7.24 egg), EM10E (10.57 g), and EM90D (140.0 g). FSHβ, LHβ, FSHR, and LHR gene mRNA expression was considerably (P < 0.05) greater in the fourth generation compared to the base generation. In conclusion, selection programs depending on the efficiency of egg production (EN90D) could improve the genetic gain of egg production traits and upregulate the mRNA expression of FSHβ, LHβ, FSHR, and LHR genes in selected quails (fourth generation). These findings might help to enhance breeding plans and create commercial lines of high egg production Japanese quails.

The aim of this study was to investigate the potential of dietary 3% oyster mushroom (Pleurotus ostreatus) waste in enhancing the anticoccidial effects in broilers challenged with Eimeria tenella infection. The experiment involved a total of 600 Japanese quails, raised from one to thirty-five days of age, which were divided into four treatment groups. These included a negative control group that received a basal diet (BD) without any anticoccidial or antibiotic supplementation in the non-challenged birds (negative control, NC); a positive control (PC) group consisting of NC birds challenged with E. tenella; a group that received the BD with an anticoccidial drug (standard); and a group that received the BD supplemented with 3% waste from oyster mushrooms (3% Pleurotus ostreatus). The results showed that the feed intake, body weight gain, and feed efficiency were significantly lower in the PC (p < 0.05). However, the growth traits were similar in the standard and 3% Pleurotus ostreatus-treated groups. Similarly, there was no difference (p < 0.05) in the mortality rate, oocyst count in the feces, and lesion score between the standard and 3% Pleurotus ostreatus groups. Based on intestinal histology evaluation, the villi height and width were significantly higher in the standard and 3% Pleurotus ostreatus-treated groups compared to those of the PC (p < 0.01). In conclusion, it was found that 3% Pleurotus ostreatus effectively mitigated the low growth rate of Japanese quails induced by coccidial infection.

The present paper aims to evaluate the effect of different levels of bovine colostrum and probiotic dietary supplementation on egg production performance, egg traits, carcass characteristics, blood biochemistry and antioxidant status of laying Japanese quails. For the trial, 240 laying quails, aged between 24 weeks and 30 weeks, were involved in a 3 × 2 factorial experimental design, with 3 levels of bovine fresh colostrum (0, 2, and 4 percent of the total ratio) and 2 levels of probiotics (0 and 0.01 percent of the total ratio) administration. The colostrum supplementation improved the egg production performance, egg traits, carcass characteristics, blood biochemistry, and antioxidant status (p < 0.01). Probiotics used without colostrum did not affect the investigated traits of laying Japanese quails (p > 0.05), but a synergistic effect was observed when combined with colostrum. The overall results recommended that using 4% of bovine colostrum in laying Japanese quails, with the addition of 0.01% of probiotic feed additive results in positive effects on egg production performance, egg traits, carcass characteristics, blood biochemistry, and antioxidant status of laying Japanese quails in the late laying period.

The present study explored the neurotoxic impacts of lead (Pb) and the potential alleviating effect of Yucca schidigera extract (YSE) in Japanese quails. About 360 adult Japanese quails (8 weeks old) were used. Quails were randomly distributed to six groups with 4 replicates each: the control group (fed basal diet, BD), the BD + YSE1 and BD + YSE2 groups (BD + 100 and 200 mg/kg diet of YSE, respectively), the Pb group (BD + 100 mg/kg Pb), and the Pb + YSE1 and Pb + YSE2 groups (BD + Pb + 100 and 200 mg/kg YSE, respectively). This feeding trial lasted for 8 weeks. The exposure to Pb in the diet induced oxidative damage stress in the brain of exposed quails reflected by the significant increase in the oxidative markers including malonaldehyde (MDA) and protein carbonyl (PC) and the significant reduction in the activities of antioxidants including catalase (CAT), superoxide dismutase (SOD), and the reduced glutathione (GSH). Brain neurochemistry and enzyme activities were also altered following Pb exposure. Pb significantly reduced serotonin, dopamine, norepinephrine, GABA, Ach, and Na + /K + -ATPase activities. Pb dietary intoxication markedly increased brain inflammatory biomarkers, including tumor necrosis factor (TNF-α), myeloperoxidase, and nitric oxide. Peripherally, Pb toxicity decreased the amino acid neurotransmitters (glutamic acid, glycine, and aspartic acid) in the serum of birds. At the transcriptomic level, Pb exposure upregulated the transcription patterns of CASP3, TNF-α, HSP70, and IL-1β. The single effect of YSE maintained that all the assessed parameters were not changed compared to the control. Interestingly, the YSE co-supplementation with Pb alleviated the Pb-induced neuro-oxidative damages by lowering the lipid, protein, and DNA damage, and the inflammatory biomarkers.

This research investigated the growth and other production traits of four distinct lines (L1, L2, L3, and L4) of Japanese quail (Cortunix japanoica) kept in the tropical climate of Tamil Nadu, India. The traits related to body weight at different weeks and weight gain were measured in 180 birds (90 males and 90 females) per line up to the fifth week of age, and then 90 birds (females only) from the sixth to the 16th week of age, with egg production and feed efficiency parameters measured in 10 observations per line. The traits were analysed using the General Linear Model procedure, and Tukey\'s HSD was used to test for statistical differences (p < 0.05) between the means for subclasses under a specific effect. The results revealed a highly significant difference (p < 0.01) in body weight from hatch to fifth week of age. At 5th week of age, the L3 and L2 did not differ (p > 0.05) based on Tukey test; therefore, both presented the highest values and were statistically significant (p < 0.01) with L4 with a lowest value of 203.62 g. The cumulative fifth week feed conversion ratio showed non-significant difference (p > 0.05) at first and second week, and highly significant difference (p < 0.01) from third to fifth week of age. The age at 50 per cent egg production was 60.2 (L4), 61.4 (L2), 65.1 (L3) and 66.0 (L1) days and the L1 egg production differed significantly (p < 0.01) from L4 line. The highest bodyweight (g) during the laying period (at 15 weeks of age) was observed in L2 (327.08) and L3 (326.54) and differed significantly (p < 0.01) from L1 (309.24) as well as L4 (288.69) lines. The mean egg weight (g) of different lines showed non-significant difference (p > 0.05) at all weeks, except at 11th week of age (p < 0.01). The mean feed consumption (g)/bird/day differed significantly (p < 0.01) from 6th to 16th week of age, except at sixth and eighth week of age, where it was non-significant (p > 0.05). The overall feed efficiency/dozen of eggs (from 6th to 16th weeks) ranged from 1.33 (L1) to 1.98 (L3). The livability from 6 to 16 weeks of age was 100 per cent in all the lines. In order to boost Japanese quail production in the tropics, L3 and L4 may be selected for body weight and egg production, respectively.

The Japanese quail (Coturnix japonica) is farmed for its eggs and meat across the globe. A series of experiments were conducted to evaluate the effect of the permanent or intermittent use of different levels of BC (bovine colostrum) on the egg performance and traits, carcass characteristics, blood biochemical and antioxidant status of laying Japanese quails. In this study, 200 laying quails were used for a duration of six weeks (week 24 to 30) to measure the selected parameters. Treatments included: (1) control (without BC); (2) 2% continuous BC; (3) 4% BC permanently; and (4) and (5) 2% and 4% BC intermittently (every other week), respectively. According to the results, performance, egg quality, carcass traits, biochemical indices and antioxidant status of BC-fed (continuous and intermittent mode) quails were improved compared to the control-diet-fed birds (p < 0.01). Per our observations, quails fed daily with 4% BC had the highest performance, best egg and carcass quality traits, best blood composition and best antioxidant status of serum, although the same parameters were also improved in birds fed intermittently with 4% BC. The final conclusion is that, although quails fed daily with 4% BC showed the best performance, intermittent feeding exerted comparable effects. Therefore, the intermittent-feeding approach could benefit the birds when colostrum preparation is limited due to the high cost of the related process. This approach could improve the economics of poultry breeding while reducing environmental problems, such as antibiotic resistance.

BACKGROUND: Insulin-like growth factor 2 (IGF2) is one of three hormones that share high structural similarity to insulin. It is involved in several insulin-like growth-regulating and mitogenic activities. This study was conducted to genotype the coding regions of the IGF2 gene in Japanese quail (Coturnix japonica) using PCR-SSCP-sequencing, and to assess the possible association of the polymorphism of these regions with the main egg production traits. A total of 240 female birds with an equal number of three Japanese quail populations (Brown or BR, Black or BL, and White or WT) were included in this study.
RESULTS: All the genotyped regions exerted no heterogeneity in their sequences with one exception detected in the exon 2. In this locus, a novel single nucleotide polymorphism (SNP) was detected in which \"A\" was substituted with \"G\" at 81 position with a silent effect (p.F79=SNP) on IGF2 protein. Association analyses indicated a significant (P < 0.05) relation of this SNP with egg number (EN) and bird weight (BW) in the analyzed populations, in which the birds with AG genotype had lower EN and BW than those with AA genotype. The p.F79=SNP was largely detected in the WT line than the other two lines.
CONCLUSIONS: The detected p.F79=SNP has a highly negative effect on EN and BW in Japanese quail. Thus, the implementation of the variations of the IGF2 gene can be a useful marker in the marker-assisted selection of Japanese quail. This is the first report to describe IGF2 gene variations in Japanese quail, which strongly suggests raising the birds from the BR line with AA genotype when breeders desire to raise Japanese quail for large-scale egg production.

Exposure to dibutyl phthalate (DBP) induces testicular damage in mammals. However, studies on the effects of DBP on spermatogenic cells in birds are grossly lacking. Therefore, this study was designed to determine the effects of the pre-pubertal exposure to DBP on the histology and ultrastructure of spermatogenic cells in the testis of adult Japanese quail (Coturnix coturnix japonica). The birds were randomly divided into five dosage groups at the age of 4 weeks. The control group received a corn oil vehicle only (a dose of 1 mL/kg body weight), while the other four experimental groups received a daily dosage of 10, 50, 200, 400 mg/kg body weight of DBP (dissolved in corn oil), respectively with the aid of gastric lavage, for 30 days. Testicular samples were processed and examined by light microscopy and transmission electron microscopy. Histopathological evaluation revealed vacuole formation, germ cell degenerations, and the absence of spermatogenic cell series. Ultrastructurally, chromatin clumps in spermatocyte and degenerated spermatogonia with ruptured nuclear membranes resting on the distorted basement membranes were observed. Others were intracytoplasmic vacuoles in round spermatids and fragments of dense apoptotic bodies. In conclusion, the findings of the present study reveal that spermatogenic cells of Japanese quails seem to be more sensitive to DBP-induced degeneration compared to mammalian species studied. The Japanese quail could be used to monitor environmental contamination with low doses of DBP.