Several models of maternal undernutrition reveal impairment of testicular development and compromise spermatogenesis in male offspring. The expansion of the litter size model, valuable for studying the impact of undernutrition on early development, has not yet been used to evaluate the consequences of early undernutrition in the adult male reproductive system. For this purpose, pups were raised in either normal litter (ten pups/dam) or large litter (LL; sixteen pups/dam). On postnatal day 90, sexual behaviour was evaluated or blood, adipose and reproductive tissues were collected for biochemical, histological and morphological analysis. Adult LL animals were lighter and thinner than controls. They showed increased food intake, but decrease of retroperitoneal white adipose tissue weight, glycaemia after oral glucose overload and plasma concentration of cholesterol. Reproductive organ weights were not altered by undernutrition, but histopathological analysis revealed an increased number of abnormal seminiferous tubules and number of immature spermatids in the tubular lumen of LL animals. These animals also showed reduction in total spermatic reserve and daily sperm production in the testes. Undernutrition decreased the number of Sertoli cells, and testosterone production was increased in the LL group. Mitochondrial activity of spermatozoa remained unchanged between experimental groups, suggesting no significant impact on the energy-related processes associated with sperm function. All animals from both experimental groups were considered sexually competent, with no significant difference in the parameters of sexual behaviour. We conclude that neonatal undernutrition induces histological and physiological testicular changes, without altering sperm quality and sexual behaviour of animals.

Cross-generational sexual relationships are a major route of transmitting HIV and STI between older and younger generations. However, previous research has focused mainly on the young women in these relationships. This study examined the characteristics of men engaging in non-marital sexual relationships with girls aged 15–19 in Nigeria. The data were drawn from the 2013 Nigeria Demographic and Health Survey, and the analysis was restricted to a sub-sample of 7557 men aged 30–49 who were sexually active in the 12 months prior to the survey. Data analysis was carried out using frequency distributions, chi-squared tests of association and binary logistic regression. It was found that 9.5% of men aged 30–49 reported engaging in cross-generational sexual relationships. Also, being older (OR = 0.35), married (OR = 0.37), having secondary or higher education (OR = 0.70; 0.59) and having sexual debut between ages 18 and 30 (OR = 0.73) were associated with a lower likelihood of having cross-generational sexual relationships. However, Muslim men (OR = 2.10), men from Igbo (OR = 1.90), Hausa/Fulani (OR = 8.47) and Northern and Southern minority tribes (OR = 4.73; 2.49), men living in rural areas (OR = 1.34), men who were over the age of 30 at sexual debut (OR = 2.67) and those with 2–4 and 5 or more lifetime sexual partners (OR = 1.43; 1.58) were significantly more likely to engage in cross-generational sexual relationships. Addressing the challenges of cross-generational sexual relationships can be an effective strategy to reduce the menace of HIV and STI transmission. Men who have low education, those aged 30–34 years, those who initiated sex at an older age, rural dwellers and those who have had several lifetime sexual partners need to be targeted while designing and implementing programmes and policies to reduce cross-generational sexual relationships in Nigeria. These interventions must also take into account the religious and cultural attitudes towards cross-generational sexual relationships, and further investigations should identify men’s motives for engaging in the practice.

Coupled with the social practice of female hypergamy, the male surplus within the never-married population means that today's Chinese marriage market is extremely tight in particular for men from a rural background and the least privileged socio-economic categories. Drawing on quantitative data from a survey conducted in 2014–2015, this article sheds light on the situation of single men who are past prime marriage age in three rural districts of Shaanxi particularly affected by this phenomenon. It compares single men's characteristics to those of their married counterparts and offers insights into the heterogeneity of single men with the aim of challenging some commonly accepted assumptions about bachelorhood in rural China. Results suggest a strong internalization of the various characteristics, centred on being able to offer social mobility to a potential wife, that a man is expected to have to be attractive to women in a context where women have more choice in mate selection. We conclude that mate selection is highly marked by class, social norms, social interactions, health, generation and age, and requires the mobilization of certain amounts of individual, social and economic resources. Unwanted bachelorhood would thus be better understood using an intersectional approach rather than mainly in numeric terms.

Sexual behavioural isolation can result from sexual selection and represents a relevant factor associated with the speciation process. We analysed the pheromone emission pattern and the courtship of males of five different populations of the Anastrepha fraterculus cryptic complex: Brazil (Vacaria, Tucumán and Piracicaba), Colombia and Peru. The time of pheromone emission was recorded in each population every 30 min during the day. The behavioural sequences of courting were video recorded and analysed using EthoSeq software. Males from different populations have showed different period of pheromone emission – Vacaria, Piracicaba and Tucumán executed calling only during the morning, Colombia only in the afternoon and Peru during both periods. The general frequencies of the courtship units of the males were distinct among the populations. Three groups were formed in the classification from the function of 14 behavioural routines: Vacaria, Piracicaba and Tucumán formed a single group (Brazil-1), while Colombia and Peru formed two distinct groups. In the probabilistic trees generated, the behavioural units that most contributed to the occurrence of copulation were distinct among the three groups formed: Brazil-1 (Contact, Alignment and Arrowhead-1); Colombia (Flying, Mobile, Contact and Alignment); Peru (Flying, Arrowhead-1 and Calling). Our results indicated differences in sexual behaviour that may explain the behavioural isolation found between the distinct groups in addition with the temporal isolation found between the Brazil-1 and Colombia populations. The evolutionary implications for the A. fraterculus cryptic species complex are discussed.

During oestrus, fattening female pigs are more prone to lameness, fractures and wounds due to mounting and agonistic behaviours of penmates. This study assessed the effect of sexual maturity on the behaviour and welfare of heavy female pigs slaughtered at 36 weeks of age (180±10 kg) for dry-cured ham production. An immunocastrated control group was used for comparison. In all, 56 15-week-old female pigs, individually identifiable by back tattoos were equally distributed among four pens. All animals from two pens were subject to a three-dose immunocastration schedule at 16, 20 and 32 weeks of age. Skin lesions and behaviours were assessed at 18, 23, 28, 33 and 36 weeks of age. A blood sample was collected at 20, 24, 28 and 32 weeks of age for assessing health/stress parameters and GnRH antibodies. At slaughter, ovaries were weighed, measured and histologically examined; stomachs, carcasses and lungs were scored for lesions and a further blood sample was taken. Immunocastrated pigs did not significantly differ from controls in growth rate, feed efficiency and slaughter performances (lung score, gastric score, backfat thickness). However, they showed a lower frequency of aggressive interactions at 33 and 36 weeks, lower front lesions at 28 weeks, but higher at 30 weeks; a lower haptoglobin level at 28 weeks, a lower level of cortisol and back lesions at slaughter (36 weeks). These findings suggest a low, yet not negligible, impact of sexual maturity on the welfare of heavy female pigs.

We investigated if sexual behaviour of rams can be assessed with an electronic Alpha-Detector (AD) which automatically records mounts of mating rams. To evaluate the rams’ libido (i.e. all sexual activities), we used six intact and six vasectomised rams in pen tests in three different seasons (late spring, autumn and early spring). The pen tests consisted of 30-min visual observations of each ram placed in a group of six Merino ewes (three ewes in oestrus and three ewes not in oestrus). In the pen tests, sexual behaviour was recorded and divided into two categories: pre-copulatory and copulatory. For validation purposes, during the pen tests the 12 rams were equipped with the AD and the number of times the 18 oestrous ewes were mounted were counted over a period of 3 days. Of the 1191 mounts visually identified in the six 30-min sessions, 1026 were recorded automatically by the AD (i.e. 94%). The paddock test is an automated method consisting of the same rams wearing an AD and placed in a flock of ~250 Merino ewes on two occasions (late spring (spring 1) and early spring of the following year (spring 2)), their copulatory activities were automatically recorded over a 5-day period. The results of the pen tests in the three seasons revealed no difference between the two types of rams (breeding v. detecting rams). Based on live observations high correlations (r=+0.81, P<0.003 for breeding and r=+0.76, P<0.02 for detecting rams) were found between pre-copulatory and copulatory behaviours. The libido of the two types of rams measured in pen tests showed high repeatability across the three seasons (83 and 75%, P<0.05 for copulatory and pre-copulatory behaviours, respectively). When measured automatically in paddock tests over two consecutive springs, even higher repeatability was observed in both breeding (94%; P<0.01) and detecting rams (97%; P<0.004) in the number of mounts. In addition, high correlations (+0.89<r<+0.94) between copulatory behaviours, as measured by live observations, and those measured by the AD were obtained. The automatic measurement of ram libido in paddock tests appears to be more reliable than pen tests and far less time consuming. We therefore recommend this automated method to estimate the libido of rams. In addition, this method can be used at any season of the year provided that ewes in oestrus are present in the flock.

Pregabalin is a γ-aminobutyric acid analogue that is primarily prescribed in psychiatry for management of generalized anxiety disorder. The belief in its low potential for abuse has placed it in a superior position to other anxiolytic agents. However, more recent, concerns have been raised about the addictive potential of pregabalin. This problem has not received much attention nor has the mechanism of its development. There is also a lack of understanding of the difference in the experience of abusing pregabalin in contrast to abusing other illicit drugs. We report the case of a 55-year-old patient with a background history of multiple psychoactive substances misuse who elaborated on his own personal experience of pregabalin abuse. He consumed a month’s supply of this medication over 2 days and realized an enhancement in sexual desire and excitement. This effect should be considered when prescribing pregabalin.

This study describes the incidence rate of reported lymphogranuloma venereum (LGV) in men who have sex with men (MSM) in Barcelona from 2007 to 2012. Epidemiological, clinical and sexual behaviour characteristics of LGV cases are described. Seroadaptive behaviours as a transmission risk factor were assessed by a telephone questionnaire during 2012. Data were handled on a strictly confidential basis. LGV annual rate ratios in MSM were compared with cases from 2007. Differences were statistically analysed with a Poisson test. The incidence rate of LGV in MSM aged 15–69 years ranged from 32·1/105 MSM per year in 2007 to 182·7/105 MSM per year in 2012. In 2012, 31/51 LGV cases (61%) answered the telephone questionnaire, of which 84% (26/31) were HIV positive, 39% (12/31) reported having sex according to their partners’ serostatus and 7% (2/31) used strategic positioning. The incidence of LGV has increased since 2007 and mainly affects HIV-positive MSM. It is probable that seroadaptation has facilitated LGV transmission.

The expression of oestrous behaviour in Holstein Friesian dairy cows has progressively decreased over the past 50 years. Reduced oestrus expression is one of the factors contributing to the current suboptimal reproductive efficiency in dairy farming. Variation between and within cows in the expression of oestrous behaviour is associated with variation in peripheral blood oestradiol concentrations during oestrus. In addition, there is evidence for a priming role of progesterone for the full display of oestrous behaviour. A higher rate of metabolic clearance of ovarian steroids could be one of the factors leading to lower peripheral blood concentrations of oestradiol and progesterone in high-producing dairy cows. Oestradiol acts on the brain by genomic, non-genomic and growth factor-dependent mechanisms. A firm base of understanding of the ovarian steroid-driven central genomic regulation of female sexual behaviour has been obtained from studies on rodents. These studies have resulted in the definition of five modules of oestradiol-activated genes in the brain, referred to as the GAPPS modules. In a recent series of studies, gene expression in the anterior pituitary and four brain areas (amygdala, hippocampus, dorsal hypothalamus and ventral hypothalamus) in oestrous and luteal phase cows, respectively, has been measured, and the relation with oestrous behaviour of these cows was analysed. These studies identified a number of genes of which the expression was associated with the intensity of oestrous behaviour. These genes could be grouped according to the GAPPS modules, suggesting close similarity of the regulation of oestrous behaviour in cows and female sexual behaviour in rodents. A better understanding of the central genomic regulation of the expression of oestrous behaviour in dairy cows may in due time contribute to improved (genomic) selection strategies for appropriate oestrus expression in high-producing dairy cows.

By surveying extensive epidemiological behavioural and sexual risk factors in a Korean twin cohort, risk factors for human papillomavirus (HPV) infection were investigated in South Korea. A total of 912 vaginal specimens were collected from the Healthy Twin Study, consisting of twins and their families. A range of epidemiological, behavioural, and sexual activity characteristics were evaluated using multivariate logistic regression analyses of family and twin relationships, adjusted to elucidate the risk factors for HPV infection. Of the various epidemiological characteristics, the possibility of extramarital affairs [odds ratio (OR) 2·48, 95% confidence interval (CI) 1·02–6·02] significantly increased the prevalence of HPV infection. Our multivariate regression analysis indicated that oral contraceptive use (OR 40·64, 95% CI 0·99–1670·7) and history of sexually transmitted disease (OR 2·56, 95% CI 0·93–7·10) were strongly associated with an increase in HPV infection. On the other hand, more frequent vaginal douching (OR 0·32, 95% CI 0·13–0·77) significantly decreased the prevalence of HPV infection. Our results suggested that HPV infection is associated with both biological and behavioural factors.

Traditionally, marriage is a near universality in China. However, in the coming decades, owing to the growing sex imbalance, millions of men will be unable to marry. As a consequence, bachelorhood is becoming a new demographic concern, particularly affecting men from the most disadvantaged socio-economic groups. In China's cultural context today, heterosexual marriage remains a prerequisite for family formation and, in rural society particularly, the legitimate setting for sexual activity. Under such circumstances, bachelorhood is likely to produce privations on various fronts, the consequences of which for both the individual and the community are still largely unknown. This article focuses on the opinions and sexual behaviour of bachelors, and highlights significant variations from those of married men. It is based on the findings of an exploratory survey conducted in 2008 in selected villages in a rural county in Anhui province, referred to here as JC county. The survey provides insights into the more general situation of rural men unable to marry in a context of female shortage, and indicates the conditions a growing number of Chinese men will face in the near future.

Human sexuality is a complex interaction of biological, social and emotional factors. When any or all of these factors are disrupted by a progressive dementia it is unsurprising that sexual ‘problems’ are identified. Most sexual behaviour ‘problems’ relate to expressions of normal sexuality complicated by changes in relationships, care needs and cognitive function, and complex ethical and legal considerations emerge. Rarely, new and severe hypersexual or paraphilic behaviours arise de novo, usually due to damage to certain brain areas, and sometimes due to medication side-effects, psychiatric disorder or delirium. Evidence and approaches to assess and to manage sexual behaviour problems in dementia are discussed.

Parasitism is defined in various ways as an intimate relationship in which one partner, the parasite, lives on or in another, the host, generally at the expense of the latter. Parasitism commonly results in a unique array of host physiological responses and adaptations. Most studies of the physiological effects of parasitism have focused on the pathological consequence of infection and disease. While many physiological changes contribute to pathogenesis, it is now recognized that parasitic infections at sub-clinical levels also produce physiological effects that either ameliorate or may not contribute to the disease process. Moreover, these physiological changes are often manifested by altered host behaviour. Behavioural studies have enabled an ecological- and evolutionary-oriented evaluation of host responses. In this fashion, physiological effects may be assessed as to whether they affect fitness and confer benefit or harm to one or both of the symbionts involved. We briefly examine how these physiological responses, specifically neural, endocrine, neuromodulatory, and immunomodulatory components, may interact to modify host behaviours. We consider the adaptiveness of these responses and how the behavioural patterns elicited may simultaneously appear adaptive for the parasite as well as the host. In addition, we address how parasite-host physiological and behavioural interactions may be altered during the course of parasitism.