Sustainable Intensification of Beef Production in the Tropics: The Role of Genetically Improving Sexual Precocity of Heifers

Increasing productivity through continued animal genetic improvement is a crucial part of implementing sustainable livestock intensification programs. In Zebu cattle, the lack of sexual precocity is one of the main obstacles to improving beef production efficiency. Puberty-related traits are complex, but large-scale data sets from different “omics” have provided information on specific genes and biological processes with major effects on the expression of such traits, which can greatly increase animal genetic evaluation. In addition, genetic parameter estimates and genomic predictions involving sexual precocity indicator traits and productive, reproductive, and feed-efficiency related traits highlighted the feasibility and importance of direct selection for anticipating heifer reproductive life. Indeed, the case study of selection for sexual precocity in Nellore breeding programs presented here show that, in 12 years of selection for female early precocity and improved management practices, the phenotypic means of age at first calving showed a strong decreasing trend, changing from nearly 34 to less than 28 months, with a genetic trend of almost −2 days/year. In this period, the percentage of early pregnancy in the herds changed from around 10% to more than 60%, showing that the genetic improvement of heifer’s sexual precocity allows optimizing the productive cycle by reducing the number of unproductive animals in the herd. It has a direct impact on sustainability by better use of resources. Genomic selection breeding programs accounting for genotype by environment interaction represent promising tools for accelerating genetic progress for sexual precocity in tropical beef cattle.

A Novel Virus of Flaviviridae Associated with Sexual Precocity in Macrobrachium rosenbergii

The iron prawn syndrome (IPS), also described as sexual precocity, results in the reduced size of farmed prawns at harvest and significant economic losses. IPS has been frequently reported in populations of farmed Macrobrachium rosenbergii since 2010, but the cause was heretofore unknown.

Precocious sexual development in a male toddler caused by unrecognized transdermal exposure to testosterone: case report and review of the literature

Objectives Exogenous exposure to transdermal testosterone is often overlooked as a cause of precocious sexual development in children. Case presentation A 16-month-old male presented for a second opinion consultation before commencing treatment with bicalutamide and anastrozole for a presumptive diagnosis of familial gonadotropin-independent male-limited sexual precocity. Enlargement of the penis was first observed at four months of age. The initial evaluation showed isolated elevation of his plasma testosterone level; however, by 16 months, his testosterone level was prepubertal and no pathogenic variants in the LHC GR gene were identified. The history revealed that his grandfather, who had cared for him regularly in the first year of life, had used testosterone gel for treatment of hypogonadism. Conclusions Despite the 2009 “black box” warning issued by the United States Food and Drug Administration (FDA) regarding potential consequences of transdermal testosterone exposure to women and children, this continues to be an important cause of sexual precocity in children. Children are often subjected to unnecessary and costly evaluation before this exposure is recognized, underscoring the importance of obtaining a thorough medical, family, and social history tailored to the differential diagnosis.

Dynamic behavior of egg weight in free-range hens discriminated by productive indicators at sexual maturity

The effects on the dynamic pattern of egg weight of five traits at sexual maturity were characterized in Campero Casilda hens. When the first egg was laid, body weight, age (an indicator of sexual precocity), weight of the first 10 eggs (an indicator of their initial weight), days needed to lay them (an indicator of regularity) and coefficient of variation of these weights (an indicator of uniformity) were recorded. All the eggs laid between sexual maturity and 72 weeks of age was weighed. Longitudinal data relating weekly average egg weight versus laying age were adjusted by non-linear regression with the Weatherup & Foster model. Birds were categorized by the values of each trait measured at sexual maturity and the category effect on the estimators of the function parameters was evaluated. Less precocious birds were heavier and laid larger eggs at the beginning of the cycle and in the asymptote, without differences on the egg weight maturation rate, in comparison to those more precocious. The latter began the laying period irregularly, requiring a greater number of days to lay the first 10 eggs and the weight of these had a higher coefficient of variation. The birds that began laying more uniform eggs in weight maintained that difference throughout the curve. Early selection of birds that begin laying at an older age, with greater body weight, more regularly and with heavier eggs uniform in size would show a favorable dynamic pattern in egg weight.