Genetic and Genomic Analyses of Service Sire Effect on Female Reproductive Traits in Holstein Cattle

Fertility and reproductive performance are key drivers of dairy farm profitability. Hence, reproduction traits have been included in a large majority of worldwide dairy cattle selection indexes. The reproductive traits are lowly heritable but can be improved through direct genetic selection. However, most scientific studies and dairy cattle breeding programs have focused solely on the genetic effects of the dam (GED) on reproductive performance and, therefore, ignored the contribution of the service sire in the phenotypic outcomes. This study aimed to investigate the service sire effects on female reproductive traits in Holstein cattle from a genomic perspective. Genetic parameter estimation and genome-wide association studies (GWAS) were performed for the genetic effect of service sire (GESS) on conception rate (CR), 56-day non-return rate (NRR56), calving ease (CE), stillbirth (SB), and gestation length (GL). Our findings indicate that the additive genetic effects of both sire and dam contribute to the phenotypic variance of reproductive traits measured in females (0.0196 vs. 0.0109, 0.0237 vs. 0.0133, 0.0040 vs. 0.0289, 0.0782 vs. 0.0083, and 0.1024 vs. 0.1020 for GESS and GED heritability estimates for CR, NRR56, CE, SB, and GL, respectively), and these two genetic effects are positively correlated for SB (0.1394) and GL (0.7871). Interestingly, the breeding values for GESS on insemination success traits (CR and NRR56) are unfavorably and significantly correlated with some production, health, and type breeding values (ranging from −0.449 to 0.274), while the GESS values on calving traits (CE, SB, and GL) are usually favorably associated with those traits (ranging from −0.493 to 0.313). One hundred sixty-two significant single-nucleotide polymorphisms (SNPs) and their surrounding protein-coding genes were identified as significantly associated with GESS and GED, respectively. Six genes overlapped between GESS and GED for calving traits and 10 genes overlapped between GESS for success traits and calving traits. Our findings indicate the importance of considering the GESS when genetically evaluating the female reproductive traits in Holstein cattle.

Frequent origins of traumatic insemination involve convergent shifts in sperm and genital morphology

Traumatic insemination is a mating behaviour during which the (sperm) donor uses a traumatic intromittent organ to inject an ejaculate through the epidermis of the (sperm) recipient, thereby frequently circumventing the female genitalia. Traumatic insemination occurs widely across animals, but the frequency of its evolution, the intermediate stages via which it originates, and the morphological changes that such shifts involve remain poorly understood. Based on observations in 145 species of the free-living flatworm genus Macrostomum, we identify at least nine independent evolutionary origins of traumatic insemination from reciprocal copulation, but no clear indication of reversals. These origins involve convergent shifts in multivariate morphospace of male and female reproductive traits, suggesting that traumatic insemination has a canalising effect on morphology. Signatures of male-female coevolution across the genus indicate that sexual selection and sexual conflict drive the evolution of traumatic insemination, because it allows donors to bypass postcopulatory control mechanisms of recipients.

Environmental and genetic influences on fitness-related traits in a hatchery coho salmon population.

Many natural and managed organisms will require substantial functional genetic variation to respond to selection in the face of rapid environmental change. Pacific salmon have experienced strong fluctuations in critical fitness traits over the past five decades. We examined genetic and phenotypic variability over three generations in a pedigreed hatchery population of coho salmon (Oncorhynchus kisutch) by monitoring seven fitness-related traits. Three-year-old adult return numbers varied more than five-fold, and jack (2-year old males) numbers varied 13-fold. Body sizes of Inch Creek coho salmon decreased consistently such that fish were only 40.7% as heavy in 2015 as in 2006 and female reproductive traits also decreased. During the study period, the majority of families produced returning adult progeny and effective population size was relatively constant. Heritability estimates for phenotypic traits were significantly greater than zero except for condition factor, and the estimated heritability for jacking was 0.42. The Inch Creek coho salmon population harbours substantial heritability for fitness and reproductive traits and thus likely retains significant capacity for adaptation despite many years of hatchery propagation.

A Systematic Two-Sample Mendelian Randomization Analysis Identifies Shared Genetic Origin of Endometriosis and Associated Phenotypes

Endometriosis, one of the most common gynecological disorders, is a complex disease characterized by the growth of endometrial-like tissue in extra-uterine locations and is a cause of pelvic pain and infertility. Evidence from observational studies indicate that endometriosis usually appears together with several other phenotypes. These include a list of autoimmune diseases, most of them more prevalent in women, anthropometric traits associated with leanness in the adulthood, as well as female reproductive traits, including altered hormone levels and those associated with a prolonged exposure to menstruation. However, the biological mechanisms underlying their co-morbidity remains unknown. To explore whether those phenotypes and endometriosis share a common genetic origin, we performed a systematic Two-Sample Mendelian Randomization (2SMR) analysis using public GWAS data. Our results suggest potential common genetic roots between endometriosis and female anthropometric and reproductive traits. Particularly, our data suggests that reduced weight and BMI might be mediating the genetic susceptibility to suffer endometriosis. Furthermore, data on female reproductive traits strongly suggest that genetic variants that predispose to a more frequent exposure to menstruation, through earlier age at menarche and shorter menstrual cycles, might also increase the risk to suffer from endometriosis.

The Genetics of Human DZ Twinning

In the course of twin studies whose main focus was elucidation of genetic and environmental factors on behavioral traits, many twin researchers became aware of the strong tendency for dizygotic (DZ) twinning to run in families. Over four decades, Nick Martin and others initiated hormone and ultrasound studies, performed segregation and pedigree analyses, tested candidate genes, carried out linkage projects in sister pairs and formed large collaborations to illuminate the genetics of DZ twinning by genome-wide association studies and meta-analysis. This article summarizes the early work on hormone and genetic studies and describes the meta-analyses that have at last met with success in finding the first genes that predispose to DZ twinning, which also appear to influence many other female reproductive traits.

REPRODUCTIVE PERFORMANCE, FEED INTAKE AND EFFICIENCY OF INDIGENOUS AND CROSSBRED TURKEYS

This study assessed the reproductive performance of indigenous and crossbred parent stocks and the influence of sire genotype on the growth and efficiency of feed utilization by their progenies. A total of 300 poults, 150 for each genotype were generated from two crosses (Nicholas white x Indigenous and Indigenous x Indigenous turkeys). Data were collected on the reproductive performance of the parents while body weight and feed intake from day old to the 20th week of age were also collected from the progenies generated. The experiment was a complete randomized design with data generated subjected to two way analysis of variance using SAS. The result of the study showed that sire genotype had significant effect (p<0.05) on semen colour and semen volume while semen pH, motility, morphology and live dead ratio were not significantly affected. Crossbred tom had higher semen volume (0.39 ml) compared to 0.18 ml recorded in indigenous turkey. Genotype had no significant effect (p>0.05) on all female reproductive traits such as fertility, hatchability, dead in-germ, weak in-shell and dead in-shell. However, the indigenous turkey had higher fertility percentage (85%) while 80% hatchability was observed in crossbred turkey. Crossbred turkey significantly (p<0.05) had higher body weight (3330g) at 20 week of age compared to the indigenous turkey (2869g). Sexual dimorphism in favour of the male turkey was also observed throughout the period of the experiment. Although the crossbred turkey consumed more feed, the efficiency of feed utilization was better in the indigenous turkey. This findings suggested that the indigenous turkeys can be successfully improved with the introgression of exotic genetic material while crossbred turkeys can be further selected for improved productive and adaptive traits.