Anogenital Distance Research Articles

Alleviative effect of quercetin against reproductive toxicity induced by chronic exposure to the mixture of phthalates in male rats

Phthalates (PEs) are widely used plasticizers in polymer products, and humans are increasingly exposed to them. This study was designed to investigate the alleviative effect of phytochemicals quercetin (Que) against male reproductive toxicity caused by the mixture of three commonly used PEs (MPEs), and further to explore the underlying mechanism. Forty-eight male SD rats were randomly and evenly divided into control group, Que group, MPEs group and MPEs+Que group (n = 12); The oral exposure doses of MPEs and Que were 450 mg/kg/d and 50 mg/kg/d, respectively. After 91 days of continuous intervention, compared with control group, the testes weight, epididymis weight, serum sex hormones, and anogenital distance were significantly decreased in MPEs group (P < 0.05); Testicular histopathological observation showed that all seminiferous tubules were atrophy, leydig cells were hyperplasia, spermatogenic cells growth were arrested in MPEs group. Ultrastructural observation of testicular germ cells showed that the edges of the nuclear membranes were indistinct, and the mitochondria were severely damaged with the cristae disrupted, decreased or even disappeared in MPEs group. Immunohistochemistry and Western blot analysis showed that testicular CYP11A1, CYP17A1 and 17β-HSD were up-regulated, while StAR, PIWIL1 and PIWIL2 were down-regulated in MPEs group (P < 0.05); However, the alterations of these parameters were restored in MPEs+Que group. The results indicated MPEs disturbed steroid hormone metabolism, and caused male reproductive injuries; whereas, Que could inhibit MPEs’ male reproductive toxicity, which might relate to the restored regulation of steroid hormone metabolism.

Using targeted fetal rat testis genomic and endocrine alterations to predict the effects of a phthalate mixture on the male reproductive tract

Administration of phthalates in utero disrupts gene expression and hormone levels in the fetal rat testis, which are key events in an Adverse Outcome Pathway (AOP) for the Phthalate Syndrome. These measures can be used to predict the postnatal adverse effects of phthalate esters (PEs) on male rat sexual differentiation. Here, pregnant rats were exposed to dibutyl (DBP)- and diisononyl (DINP) phthalate on gestational days 14 to 18 individually and as a mixture (DBP,250 mg/kg/d; DINP, 750 mg/kg/d; and DBP 250 mg/kg/d plus DINP 750 mg/kg/d). We found that each PE reduced testosterone production (T Prod) and related gene transcripts by about 50 % and that they acted in a dose additive manner, reducing T Prod and gene expression by 75 % as a mixture. Based upon effects on T Prod, DINP was 0.33 times as potent as DBP and thus the DBP + DINP mixture was predicted to be equivalent to 500 mg DBP/kg/d.Logistic regression models of T Prod predicted that the adverse effects of the DBP + DINP mixture group versus the DBP and DINP individual treatments would reduce anogenital distance (AGD) by 27 % versus 10 %, increase hypospadias in 18 % versus < 1 %, induce epididymal agenesis in 46 % versus 10 %, and increase areolae/nipples in 4.8 % versus < 0.1 % of the, respectively. These predictions were highly consistent with effects from previously published dose response studies on the male reproductive effects of DBP. In summary, these results support the use of this New Approach Method to predict the detrimental effects of PEs and PE mixtures, replacing or reducing the need to run long-term, resource and animal use intensive extended one-generation reproduction studies for this class of chemicals.

Anogenital Distance for Detection of Fetal Sex in First Trimester

Anogenital Distance for Detection of Fetal Sex in First Trimester

Racial disparities affect the association between gestational urinary phthalate mixtures and infant genital measures.

Phthalates are ubiquitous anti-androgenic endocrine disrupting chemicals found in personal care products, medications, and many plastics. Studies have shown a racial disparity in phthalates exposure among U.S. women, which may also impact fetal development. We conducted a prospective cohort study of gestational exposure to a phthalates mixture in a racially-diverse population to determine their association with genital development. Mid-gestation (18-22 weeks) urine was collected from 152 women who self-identified as non-Hispanic Black and 158 women who self-identified as non-Hispanic White in Charleston, South Carolina between 2011 and 2014. We measured eight phthalate monoester metabolites in urine using liquid chromatography tandem-mass spectrometry. Mid-gestational penile dimensions were measured using ultrasound and anogenital distances were measured postnatally. We used Bayesian kernel machine regression to estimate the associations among the mixture of phthalate metabolites and mid-gestation penile dimensions and postnatal anogenital distance measures among singleton male (n = 179) and female (n = 131) infants, adjusted for urinary specific gravity, maternal age, body mass index, education level, cigarette smoking, and gestational age at enrollment or birth weight z-score. We found a stronger association between greater phthalates and decreased anopenile distance among infants born to women who self-identified as Black. Mono (2-ethylhexyl) phthalate (MEHP) was the driving mixture component among Black women, and monobutyl phthalate (MBP) and monoethyl phthalate (MEP) were drivers among White women. We also identified a non-linear association between phthalates and lesser ultrasound penile volume among women who self-identified as Black with monoisobutyl phthalate (MiBP) and MBP being most important. We also found an association between greater phthalates and shorter anoclitoral distance among infants born to women who self-identified as Black, with MEP and monobenzyl phthalate (MBzP) contributing most to this association. Our results suggest a disparity in the association between gestational exposure to a mixture of phthalates and fetal genital development among women who self-identified as Black compared to White.

Loss of NR5A1 in mouse Sertoli cells after sex determination changes cellular identity and induces cell death by anoikis.

To investigate the role of the nuclear receptor NR5A1 in the testis after sex determination, we analyzed mice lacking NR5A1 in Sertoli cells (SCs) from embryonic day (E) 13.5 onwards. Ablation of Nr5a1 impaired the expression of genes characteristic of SC identity (e.g. Sox9 and Amh), caused SC death from E14.5 onwards through a Trp53-independent mechanism related to anoikis, and induced disorganization of the testis cords. Together, these effects caused germ cells to enter meiosis and die. Single-cell RNA-sequencing experiments revealed that NR5A1-deficient SCs changed their molecular identity: some acquired a 'pre-granulosa-like' cell identity, whereas other reverted to a 'supporting progenitor-like' cell identity, most of them being 'intersex' because they expressed both testicular and ovarian genes. Fetal Leydig cells (LCs) did not display significant changes, indicating that SCs are not required beyond E14.5 for their emergence or maintenance. In contrast, adult LCs were absent from postnatal testes. In addition, adult mutant males displayed persistence of Müllerian duct derivatives, decreased anogenital distance and reduced penis length, which could be explained by the loss of AMH and testosterone synthesis due to SC failure.

Effects of perinatal exposures to a TAML catalyst on the mammary gland and hormone-sensitive outcomes in male mice

Estrogenic chemicals are common pollutants in wastewater and current effluent treatment processes are not typically effective in removing these compounds. Tetra-amido macrocyclic ligands (TAMLs) are catalysts that mimic endogenous peroxidases that may provide a solution to remove environmental pollutants including low concentrations of estrogenic compounds. Yet relatively little is known about the toxicity of TAMLs, and few studies have evaluated whether they may have endocrine disrupting properties. We administered one of three doses of a TAML, NT7, to mice via drinking water throughout pregnancy and lactation. Two pharmacologically active compounds, ethinyl estradiol (EE2) and flutamide were also included to give comparator data for estrogen receptor agonist and androgen receptor antagonist activities. Male pups were evaluated for several outcomes at weaning, puberty, and early adulthood. We found that EE2 exposures during gestation and the perinatal period induced numerous effects that were observed across the three ages including changes to spleen and testis weight and drastic effects on the morphology of the mammary gland. Flutamide had fewer effects but altered anogenital distance at weaning as well as spleen, liver, and kidney weight. In contrast, relatively few effects of NT7 were observed, but included alterations to spleen weight and modest changes to adult testis weight and morphology of the mammary gland at weaning. Collectively, these results provide some of the first evidence suggesting that NT7 may alter some hormone-sensitive outcomes, but that the effects were distinct from either EE2 or flutamide. Additional studies are needed to characterize the biological activity of this and other TAML catalysts.

Long-lasting developmental effects in rat offspring after maternal exposure to acetamiprid in the drinking water during gestation.

Neonicotinoids (NNTs) are a class of insecticides proposed to be safe for pest control in urban, suburban, and agricultural applications. However, little is known about their developmental effects after repeated low-dose exposures during gestation. Here, we tested a dose considered subthreshold for maternal toxicity in rats (6 mg/kg/day) by assessing several morphological, biochemical, and neurobehavioral features in preterm fetuses and developing pups after maternal administration of the NTT acetamiprid (ACP) dissolved in the drinking water during gestational days (GD) 2-19. The exploratory evaluation included monitoring maternal body weight gain, fetal viability, body weight and sex ratio, cephalic length, neonatal body weight and sex ratio, metabolic enzymes in the placenta, maternal blood and fetal liver, and anogenital distance and surface righting response during infancy. We also used the circling training test to study the integrity of the associative-spatial-motor response in adolescence. Results showed no consistent findings indicating maternal, reproductive or developmental toxicity. However, we found ACP effects on maternal body weight gain, placental butyrylcholinesterase activity, and neurobehavioral responses, suggestive of a mild toxic action. Thus, our study showed a trend for developmental susceptibility at a dose so far considered subtoxic. Although the ACP concentration in environmental samples of surface water and groundwater has been mostly reported to be much lower than that used in our study, our results suggest that the ACP point of departure used in current guidelines aimed to prevent developmental effects may need to be verified by complementary sensitive multiple-endpoint testing in the offspring.

Effects of different volumes of ovariectomy on fertility and offspring development of rats.

The purpose of this study was to explore the effect of removal of different volumes of ovarian tissue on fertility and offspring development of SD rats. SD rats were randomly divided into 6 groups according to different volumes of ovariectomy: Sham group (n=6), non-ovariectomized; 25%-OVX group (n=6), with half of the left ovary excised; 50%-OVX group (n=5), with the left ovary excised; 75%-OVX group (n=5), with the left ovary and half of the right ovary excised; 87.5%-OVX group (n=6), with the left ovary and three quarters of the right ovary excised; 100%-OVX group (n=6), with bilateral ovaries excised. These female rats (F0) were mated with healthy male rats one and four months after the surgery, and the offspring of F0 rats were named F11mon and F14mon, respectively. The number of days from mating to delivery and number of live cubs were recorded. At postnatal day 21 (P21), the body weight, length and anogenital distance (AGD) of the cubs were measured. There were no differences in the number of live cubs between 25%-OVX, 50%-OVX and sham groups. Rats in the 87.5%-OVX group did not give birth at 1 month and 4 months after the operation. When compared with the sham group, the body weight and length of F11mon at P21 were increased in 25%-OVX group and 50%-OVX group. However, after the second delivery, we controlled each mother's lactation to no more than eight pups. As a result, there were no differences in the body weight, length and AGD of F14mon compared with sham group. Removal of less than 50% of the ovaries did not affect the fertility of rats and offspring development of rats.

Evaluation of the relationship between polycystic ovary syndrome and anogenital distance

Evaluation of the relationship between polycystic ovary syndrome and anogenital distance

The Effect of Photoperiod Duration on Humoral Innate and Humoral Adaptive Immune Responsiveness in Campbell’s Dwarf Hamster

We studied the humoral innate immune responsiveness (HII), i.e. a hemolysis of rabbit erythrocytes by complement proteins, and adaptive humoral (antibody production) immune responsiveness (AHI) to SRBC, morphological and hormonal reproductive characteristics and stress level in male Campbell hamsters kept under long-day (LD; 16D: 8N) and short-day (SD; 8D: 16N) photoperiods. The results indicate lower HII, but not AHI in SD. In SD males we observed body mass, anogenital distance, midventral gland size and level of testosterone in the peripheral blood (but not the level of cortisol) decreased. Comparison of SD non-responders, SD responders and LD individuals demonstrated a statistically significant increase of HII in SD photosensitive hamsters, but not in non-responders compared to LD. There was no link between HII and AHI, which indicates an independent photoperiodic responsiveness of different branches of the immune system in Campbell’s hamster.

Morphometric Examination of Anogenital Distance, Penis and Clitoris Dimensions in Human Fetuses

Morphometric Examination of Anogenital Distance, Penis and Clitoris Dimensions in Human Fetuses

Phenotypic and genetic relationships among anogenital distance, anti-Müllerian hormone, and in vitro embryo production in Gyr dairy cattle

Anti-Müllerian hormone (AMH) concentration and number of recovered oocytes (ROOC) are phenotypic parameters associated with in vitro embryo production (IVEP). More recently, anogenital distance (AGD) has been proposed as a proxy for fertility in dairy cattle that is easy to collect at a low cost. The aim of this study was to characterize the AGD and its phenotypic and genetic associations with AMH and IVEP in Bos indicus Gyr dairy cattle. The hypothesis was that the number of ROOC, in vitro-produced embryos, and AMH concentration would increase as the AGD decreases. From July to December 2021, a single morphometrical measurement of AGD was collected in 552 donors from 6 herds in Brazil. A subset of donors had AMH assayed on the same day. Only ovum pick-up events that occurred up to 12 mo preceding and 7 mo succeeding the AGD measurement were used to assess the association between AGD, AMH, and IVEP. Thus, 472 donors (1,551 ovum pick-up events and 140 donors with AMH) were considered in the analysis. A raw average was calculated for each individual donor's ROOC, viable oocytes, total produced embryos, viability rate, and embryo rate (defined as total produced embryos/viable oocytes). Comparisons were conducted within the age categories of 3 to <6 yr or 6 to <10 yr. Phenotypic associations were performed in SAS software (SAS Institute Inc., Cary, NC). Genetic correlations were estimated using the BLUPF90 family of programs. The AGD (128.7 mm ± 14; mean ± standard deviation) had a normal distribution and was highly variable (83 to 172 mm) among the Gyr population. Our experimental hypothesis was partially supported by a phenotypic association of a greater number of total produced embryos (R2 = 0.023) as AGD decreased. Our results failed to support an increase in AMH concentration along with a decrease in AGD. In addition, positive and low genetic correlations were observed between AGD and viable oocytes (r = 0.08), and embryo rate (r = 0.20). A greater number of viable oocytes and embryos were observed in donors in the high compared with intermediate and low ROOC categories within both age categories. The age interval of 3 to <6 yr showed a greater number of recovered and viable oocytes for the high AMH compared with the low category, but no differences were observed among the AGD categories. In summary, for the Gyr breed, AGD was phenotypically inversely associated with a quantity-related parameter, such as the total number of produced embryos. In contrast, AGD showed a low genetic correlation with qualitative-related outcomes such as viable oocytes and embryo rate. Further studies should be performed to validate these retrospective analyses and to better understand the association between AGD and IVEP.

The correlation between Anogenital Distance (AGD) and Endometriosis

Link of Video Abstract: https://youtu.be/XmIf_eavZto Background: Endometriosis is a disease that causes recurrent chronic pain related to menstruation in around 10% of women of reproductive age. However, current non-invasive diagnostic tools are not sufficiently good at detecting endometriosis. Anogenital Distance (AGD) is a new measurement parameter that is non-invasive and proven to be used to help detect endometriosis. This study aims to assess the ability of AGD in detecting endometriosis. Methods: This study is a diagnostic test study involving 35 endometriosis patients and 35 controls by comparing the clinical characteristics of the patients and the length of AGD-AF and AGD-AC for both groups. Data were analyzed using SPSS version 22.0 for Windows. Results: The median AGD-AF length in endometriosis patients and controls were 22.65 + 6.54 and 29.53 + 3.52 (p&lt;0.001) respectively, with AGD-AC lengths being 68.04 + 5.8 and 66.81 + 5.49 (p=0.369). In the multivariate logistic regression test, AGD-AF length was a single significant predictor (p &lt;0.001). Based on the ROC curve, the length of AGD-AF with a cut-off of 23.35 mm has a sensitivity and specificity value of 97.1% and 65.7%. Conclusion: This study states that there is a correlation between AGD and endometriosis, especially AGD-AF, so it can be used as one of the predictors to help detect endometriosis.

Maternal-fetal safety evaluation of an aqueous extract of Casearia sylvestris leaves in rats.

This study evaluated the maternal, embryotoxic, and teratogenic effects of the aqueous extract of Casearia sylvestris (AECS), a species listed in the Unique Health System of Brazil, and widely used for treating several conditions, such as diarrhea, wounds, pain, and ulcers. Pregnant rats were daily treated orally with 0, 175, 350, or 700 mg/kg/body weight of AECS, from gestational day (GD) 6 to 15 (organogenesis period). On GD 20, the pregnant rats were euthanized, and the litters submitted to an assessment of fetal development. No clinical signs of toxicity were observed in the dams during the treatment. In the embryo-fetal development study, a significant increase in the basal zone height of the placenta was observed in the intermediate dose group. Furthermore, there was a significant increase in the relative anogenital distance measurement of female fetuses in the lowest and intermediate dose groups. Although no visceral abnormalities were observed in the treated-fetuses, skeletal anomalies evidenced by changes in the ossification of the sternum and the presence of supernumerary ribs were found in the intermediate and high dose groups. In conclusion, the treatment with AECS during organogenesis at this dose level had detrimental effects on the normal development of fetuses.

THU574 Hsd17b1 Partially Compensates For The Lack Of Hsd17b3 In Testicular Testosterone Production In Fetal Mice, But Not In Adults

Abstract Disclosure: M. Poutanen: None. A. Junnila: None. P. Sipilä: None. I.T. Huhtaniemi: None. Hydroxysteroid (17β) dehydrogenase type 3 (Hsd17b3) is the primary enzyme converting androstenedione to testosterone in human testes. HSD17B3 deficiency is a known cause of a disorder of sex development (DSD), where XY individuals are born with a female appearance, but are virilized during puberty as testosterone starts to suddenly rise due to unknown compensatory mechanisms. We have previously established and characterized an Hsd17b3 knockout mouse line (HSD17B3KO). HSD17B3KO males were born phenotypically normal, but presented various signs of under-masculinization at later ages. However, although they have very high circulating androstenedione at adulthood, they also maintain normal-to-high concentrations of testosterone. Indeed, testosterone was only seen to be low during certain fetal and pubertal time points. We suspected that Hsd17b1, capable of catalyzing the same reaction and expressed in testes towards the end of the fetal development, could be responsible for the compensation in the testosterone production, especially in the presence of higher than normal concentrations of androstenedione. To test this, we created an Hsd17b1-Hsd17b3 double KO (DKO) mouse line. The loss of both Hsd17b1 and Hsd17b3 had a more drastic effect on the phenotype of the male animals than was observed in HSD17B3KO. The outward appearance of the DKO males was completely feminized both as newborns and at adulthood, with an anogenital distance comparable to females. The male internal genitalia were present, but compared to HSD17B3KO they were further reduced in size, as were several other androgen-sensitive tissues. However, the testes and epididymides of the DKO contained high number of mature spermatozoa. The loss of both enzymes had a clear effect on the testis steroidogenesis of the newborn animals, with a 2-fold increase in intra testis androstenedione and 6-fold decrease in testosterone concentration compared to WT and HSD17B3KO males. In contrast, at the age of 3 months, no difference in the circulating steroid concentrations was observed between the DKO and HSD17B3KO, and high concentrations of androstenedione and testosterone was present in both mice. This, along with the active spermatogenesis, imply that in a presence of high LH, a further compensatory mechanism of testosterone production is present in the adult testes. In conclusion, our results demonstrate that in the absence of Hsd17b3, Hsd17b1 is crucial for the remaining testosterone production capacity in fetal mouse testis. However, in adult animals, the compensatory role is taken over by other, so far unknown, enzymes. Compared to HSD17B3KO, the overall phenotype of the DKO male mice is more similar to that of the humans with HSD17B3 deficiency, while the phenotype of HSD17B3KO is less feminized. Presentation Date: Thursday, June 15, 2023

Reproductive toxicity following in utero and lactational exposure to a human-relevant phthalate mixture in rats.

This rodent (Wistar rats) study examined reproductive effects of in utero/lactational exposure to a mixture of 6 antiandrogenic phthalates (PMix): diisobutyl phthalate, di-n-butyl phthalate, diisopentyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, and diisononyl phthalate. The PMix was defined based on exposure data from pregnant women in Brazil. Experimental groups were established by extrapolating the estimated human dose to rats (0.1 mg/kg/day), followed by up to 3 additional doses corresponding to 5, 1000, and 5000 times the starting rat dose: 0 (control), 0.1, 0.5, 100, and 500 mg/kg/day. The fetal experiment assessed gestational exposure effects on fetal gonads, whereas the postnatal experiment evaluated reproductive parameters in males and females after in utero and lactational exposure. Prenatal exposure decreased fetal testicular testosterone production at 0.5 and 500 mg/kg/day. PMix 500 also reduced mRNA expression of steroidogenesis-related genes, upregulated transcript expression of the retinoic acid-degrading enzyme Cyp26b1, and increased multinucleated gonocytes incidence in fetal testes. Postnatal assessment revealed antiandrogenic effects at the highest dose, including reduced anogenital distance, nipple retention, and decreased weight of reproductive organs. Early puberty onset (preputial separation) was observed at the lowest dose in males. In contrast, females did not show significant changes in fetal and adult endpoints. Overall, the PMix recapitulated early and late male rat phthalate syndrome phenotypes at the highest dose, but also induced some subtle changes at lower doses, which warrant confirmation and mechanistic assessments. Our data support the use of epidemiologically defined mixtures for exposure risk assessments over traditional toxicological approaches.

Shorter Anogenital Distance in Women with Ovarian Endometriomas and Adenomyosis, but Not Uterine Leiomyomas.

We investigated whether anogenital distance (AGD) is associated with adenomyosis, endometriosis and uterine leiomyomas (UL, also called uterine fibroids). We recruited 81 women with UL, 105 with ovarian endometrioma (OE), 116 with adenomyosis, 28 with both adenomyosis and UL, and 100 control subjects with other acquired gynecological conditions but not endometriosis, adenomyosis, UL, or polycystic ovarian syndrome. Measurements from the anterior clitoral surface to the center of the anus (AGDAC), from the tip of the clitoris to the center of the anus (AGDACt), and from the posterior fourchette to the center of the anus (AGDAF) were made in all subjects. Multiple regression was performed to estimate the association between AGDs and presence of OE, adenomyosis, and UL while controlling for possible confounding factors. We found that, compared with controls, women with OE and adenomyosis, but not UL, had significantly shorter AGDAF, but not AGDAC. However, the amount of variance that could be explained by the disease status is rather moderate, suggesting that factors other than disease status, bodyweight and height were also responsible for AGD. Thus, prenatal exposure to reduced levels of androgen may increase the risk of developing endometriosis and adenomyosis. However, other factors may also contribute to the pathogenesis of endometriosis and adenomyosis.

Effects of an App-Based Mindfulness Intervention during Pregnancy on the Infant's Prenatal Androgen Exposure: A Randomized Controlled Pilot Trial.

Prenatal androgen exposure modulates the development of the brain, with lasting effects on its function and behavior over the infant's life span. Environmental factors during pregnancy, in particular maternal stress, have been shown to influence the androgen load of the unborn child. We here addressed the research gap on whether a mindfulness intervention or a pregnancy education administered to pregnant women more affects the androgen exposure of the unborn child (quantified by the proxies of second-to-fourth digit length ratio (2D:4D) and anogenital distance assessed one year after delivery and at delivery, respectively). Moreover, we tested the mindfulness intervention's effects on maternal perceived stress, anxiety, depressiveness, and mindfulness. Pregnant women (gestation weeks 8-14) were randomized to a 15-week app-based mindfulness-oriented intervention (N = 72) or a pregnancy education intervention (control condition; N = 74). The mindfulness-oriented group did not significantly differ from the pregnancy education group in infants' 2D:4D or anogenital distance (partial η2 ≤ 0.01) or in maternal stress, anxiety, depressiveness, or mindfulness. However, the descriptive results indicate that across pregnancy, stress and anxiety decreased and mindfulness increased in both groups. Overall, this study did not show that the mindfulness intervention (relative to the pregnancy education) reduced the prenatal androgen exposure of the unborn children or improved the maternal outcomes significantly.

Social behaviour and personality profiles of breeding does housed part-time in group.

Housing breeding female rabbits in multi-litter instead of single-litter cages allows for more natural behaviour and social contact with conspecifics. Hierarchy fights among does, however, inhibit uptake on farms. Past focus on high reproductive performances in single-litter cages may have yielded rabbit breeds that are less suited to living in groups. For (part-time) multi-litter systems, it may prove beneficial to identify does with personality traits that are desirable for group-living and that promote the rapid formation and maintenance of a stable social hierarchy without grave injuries and prolonged stress. In this trial, we aimed to profile the personality of does by investigating the consistency of their social behavioural strategy when mixed in different groups. We further tested if strategy and personality of does were linked with skin injuries in the groups and if skin injuries could serve as a proxy to identify doe strategies and profiles. During three consecutive reproduction cycles, three or four does and their 22-day-old kits were housed in multi-litter cages for a period of 13 days (N = 51 does in total). Doe agonistic behaviour was recorded during the first 24 h (cycle 1 and 2) and the first 8 h (cycle 3) after grouping. Cluster analysis revealed two social behavioural strategies does adopted when a new group was formed: ‘offensive’ (36.8%) versus ‘submissive/avoider’ (63.2%). From all does that participated in the study for all three reproduction cycles (N = 32), 46.9% changed strategy at least once between cycles and were identified as an ‘all-rounder’ personality profile. Two other profiles were identified for does that did not change between cycles: ‘consistently submissive’ (40.6%) and ‘consistently offensive’ (12.5%). The presence of both ‘stable’ and ‘unstable’ does suggests that some does adjust their behaviour in response to their social environment. No significant correlations were found between injuries at both individual and group level and doe strategy or profile. Likewise, results could not confirm if skin injuries were a good proxy to identify doe strategy or profile. Future investigations could explore alternatives to identify ‘sociable’ does without relying on intensive behavioural studies (e.g. ano-genital distance of female kits at birth). Additionally, it needs to be ascertained whether removing offensive behaving does would indeed lead to reduced aggression and stress in group housing systems. ImplicationsBreeding female rabbits may benefit from group housing but aggressive behaviour compromises animal welfare and commercial uptake. To gain knowledge on the social dynamics between does, we investigated whether problematic agonistic behaviour could be a stable personality trait. This could facilitate selection towards ‘sociable’ on-farm doe groups. Results showed that social behaviour strategies (offensive or submissive/avoider) were stable across three successive production rounds in half of the does. Other does showed more flexibility, possibly depending on group composition. Links between doe behaviour and skin injuries (including those of group mates), however, are missing which makes identification and practical uptake challenging.

Phthalates and anogenital distance: phthalates in maternal urine vs. placental tissue, by tissue type, by timepoint, and by genital measure

Phthalates and anogenital distance: phthalates in maternal urine vs. placental tissue, by tissue type, by timepoint, and by genital measure