Undernutrition in early life remains a significant public health challenge affecting millions of infants and young children globally. Children who are wasted, stunted or underweight are at increased risk of morbidity and mortality. Undernutrition at critical periods also impacts on aspects of neurodevelopment, with longer-term consequences to educational performance and mental health outcomes. Despite consistent evidence highlighting an increased risk of neonatal and infant mortality among boys, a common assumption held across many disciplines is that girls are more vulnerable with respect to early-life exposures. In relation to undernutrition, however, recent evidence indicates the reverse, and in contexts of food insecurity, boys are at increased risk of undernutrition in early life compared to girls, with sex-specific risks for neurodevelopmental deficits. These effects appear independent of social factors that may favour boys, such as gender disparities in infant feeding practices and health-seeking behaviours. The observed vulnerability among boys may therefore be underpinned by biological processes such as differential energy requirements during periods of rapid growth. As boys have greater needs for growth and maintenance, then, in times of nutritional hardship, these needs may not be met resulting in risk of undernutrition and subsequent health consequences. In view of this emerging evidence, a greater understanding of the mechanisms behind this vulnerability among boys is needed and policy considerations to protect boys should be considered. This review will explore sex differences in risk of undernutrition and consider these in the context of existing programmes and policies.

Visceral organs play an important role in animals' energy requirements, so their growth must be well understood. The objective of the current study was to fit and compare growth curves that best describe body and visceral organ growth over time in Saanen goats of different sexes. Data were synthesized from seven studies in which curves were fitted to visceral organ growth over time for female, intact male and castrated male Saanen goats from 5 to 45 kg body weight. The liver, pancreas, spleen, rumen–reticulum, omasum, abomasum, small intestine, large intestine and mesenteric adipose tissue (MAT) data were fitted to eight models: simple linear regression, quadratic, monomolecular, Brody, Von Bertalanffy, logistic, Gompertz and Richards. The best-fit model was chosen based on the corrected Akaike information criterion and the concordance correlation coefficient. Model parameters for each sex were compared. Overall, the model that best described visceral organ growth was the logistic model. Sex did not influence the parameters that predicted organ growth (g), except for MAT, where females presented a lower tissue deposition rate and greater inflection point than males. Irrespective of sex, at the beginning of the growth curve, the liver accounted for 28 ± 1.1 g/kg of empty body weight, and the inflection point occurred at 1.7 months. The rumen–reticulum and large intestine presented higher growth rates in the first 2 months of life. Knowledge of the visceral organ growth curve is useful in improving the understanding of the effect of nutritional requirements for goats and must be used to optimize the nutritional plans.

In birds, vector-borne parasites invading the bloodstream are important agents of disease, affect fitness and shape population viability, thus being of conservation interest. Here, we molecularly identified protozoan blood parasites in two populations of the threatened Aquatic Warbler Acrocephalus paludicola, a migratory passerine nesting in open marsh. We explored whether prevalence and lineage diversity of the parasites vary by population and whether infection status is explained by landscape metrics of habitat edge and individual traits (body mass, fat score, wing length and sex). Aquatic Warblers were infected by genera Plasmodium, Leucocytozoon and Trypanosoma, with seven, one and four lineages, and 29.9, 0.7 and 12.5% prevalence, respectively. No Haemoproteus infections were detected. Prevalence did not vary between the populations, but lineage diversity was higher in Polesie than in Biebrza for all the lineages pooled and for Plasmodium. Infection by Trypanosoma decreased with patch core area and increased with density of habitat edge. Infection status was not predicted by the individual traits. Our study is the first to show an association between edge-related landscape features and blood parasitism in an open habitat bird. This finding will support informed conservation measures for avian species of the globally shrinking marshland and other treeless habitats.

The relationship between the genetic and environmental risk factors for alcohol use disorders (AUD) detected in Swedish medical, pharmacy, and criminal registries has not been hitherto examined. Prior twin studies have varied with regard to the detection of shared environmental effects and sex differences in the etiology of AUD. In this report, structural equation modeling in OpenMx was applied to (1) the three types of alcohol registration in a population-based sample of male–male twins and reared-together full and half siblings (total 208,810 pairs), and (2) AUD, as a single diagnosis, in male–male, female–female, and opposite-sex (OS) twins and reared-together full and half siblings (total 787,916 pairs). An independent pathway model fit best to the three forms of registration and indicated that between 70% and 92% of the genetic and 63% and 98% of the shared environmental effects were shared in common with the remainder unique to each form of AUD registration. Criminal registration had the largest proportion of unique genetic and environmental factors. The best fit model for AUD estimated the heritability to be 22% and 57%, respectively, in females and males. Both shared (12% vs. 6%) and special twin environment (29% vs. 2%) were substantially more important in females versus males. In conclusion, AUD ascertained from medical, pharmacy, and criminal Swedish registries largely share the same genetic and environmental risk factors. Large sex differences in the etiology of AUD were seen in this sample, with substantially stronger familial environmental and weaker genetic effects in females versus males.

Birthweight was measured on 188 monochorionic monozygotic, 54 dichorionic monozygotic, 102 like-sexed dizygotic, and 94 unlike-sexed dizygotic liveborn twin pairs. Overall, males were found to be significantly heavier than females. These differences were not significant, however, when birthweights were compared within zygosity/chorion-type categories. Males were also characterized by a slightly greater overall total variance. Comparisons of intrapair variation of monochorionic and dichorionic monozygotic twins revealed significant differences between monochorionic pairs and dichorionic separate pairs and no significant differences between monochorionic pairs and dichorionic fused pairs. The results of this study suggest that placental proximity may have as important an influence on variation in birthweight as does the presence or absence of vascular anastomoses.