Abstract Seasonal reproductive inefficiency is still observed in modern swine facilities. We previously reported global placental methylation activity was reduced from summer breedings and tended to be less from semen collected during cooler periods. Our objective was to evaluate chromatin modification marks within swine placenta in relationship to breeding season, semen collection season, and semen storage. White composite gilts were artificially inseminated in August or January using single-sire semen that was collected during warm or cool periods and stored as either cryopreserved or cooled-extended. Gilts were harvested 45 d post-breeding and placental samples from the smallest, average, and largest fetus in each litter were collected and stored at -80C until RNA extraction. An RT2 Profiler assay featuring 84 known chromatin modification enzyme targets was performed using placental RNA pooled by litter. Real-time quantitative PCR results were analyzed using the MIXED procedure and p-values were Hochberg corrected using the MULTTEST procedure in SAS. The complete model included the fixed effects of: breeding season (winter or summer), semen collection season (cool or warm), semen storage (cooled-extended or cryopreserved), interactions; boar as repeated effect; and plate as random effect. If interactions were not significant, only main effects were tested. The genes; ATF2, AURKA, and KDM5 were different (P < 0.05) by interaction of breeding season, semen collection season, and semen storage. In general, the greatest (P < 0.05) expression was in placentas derived from summer breedings. Expression of AURKA was also influenced by semen collection and storage. Expression of placental KDM5 from winter breedings was also greater (P < 0.05) from semen collected during cool periods. Placental expression of; ASH2L, DNMT3B, ESCO1, HDAC2, ING3, KDM6B, MYSM1, and SMYD3 were greater (P < 0.05) from summer breedings. Increased expression of known chromatin modification genes, from placentas derived from summer breedings, are likely responsible for reduced global methylation activity.
Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife
Abstract Increased numbers of antral follicles are associated with greater fertility and a uterine environment that is more supportive of early embryonic development in beef heifers. Glucose is a primary energy source for embryos and glucose concentrations are elevated in uterine luminal fluid (ULF) of pregnant heifers. We hypothesized that ULF glucose concentrations and endometrial transcript abundance for glucose transporters at d16 after insemination would be greater in heifers with increased numbers of antral follicles. Heifers classified with either increased (32 ± 1.1) or diminished (14.7 ± 1.1) antral follicle counts were selected and artificially inseminated following the Select Synch protocol (d0). At d16 after insemination, heifers were sent to the abattoir and reproductive tracts were collected to retrieve conceptuses to determine pregnancy. Uterine luminal fluid was collected, the endometrium was biopsied, total RNA was extracted and glucose transporter transcript abundance was determined. Data were analyzed using the MIXED procedure of SAS with antral follicle group, pregnancy status, and the interaction as fixed effects. Glucose concentrations in ULF were greater (P < 0.05) in heifers with increased antral follicle numbers compared to heifers with diminished numbers (122.65 ± 11.91 vs 84.12 ± 12.42 mg/dL). Glucose ULF concentrations were increased (P < 0.05) in pregnant vs. non-pregnant heifers (124.84 ± 12.81 vs 81.93 ± 11.50 mg/dL). Endometrial glucose transporter 1 (GLUT1) transcript abundance was increased in pregnant heifers (P < 0.01) but was not different due to antral follicle number or the interaction. Therefore, differences in glucose concentrations associated with antral follicle number may be due to differences in GLUT1 transcription before d16 or due to differences in protein abundance or functionality. Taken together, heifers with increased number of antral follicles may have increased energy availability in the uterus for trophoblast proliferation and function. USDA is an equal opportunity provider and employer.
Significant increases in litter size within commercial swine production over the past decades have led to increases in preweaning piglet mortality due to increase within-litter birthweight variation, typically due to mortality of the smallest littermate piglets. Therefore, identifying mechanisms to reduce variation in placental development and subsequent fetal growth are critical to normalizing birthweight variation and improving piglet survivability in high-producing commercial pigs. A major contributing factor to induction of within-litter variation occurs during the peri-implantation period as the pig blastocyst elongates from spherical to filamentous morphology in a short period of time and rapidly begins superficial implantation. During this period, there is significant within-litter variation in the timing and extent of elongation among littermates. As a result, delays and deficiencies in conceptus elongation not only contribute directly to early embryonic mortality, but also influence subsequent within-litter birthweight variation. This study will highlight key aspects of conceptus elongation and provide some recent evidence pertaining to specific mechanisms from -omics studies (i.e., metabolomics of the uterine environment and transcriptomics of the conceptus) that may specifically regulate the initiation of conceptus elongation to identify potential factors to reduce within-litter variation and improve piglet survivability.
The objective of this study was to determine the effects of undefined and semidefined culture systems for in vitro embryo production on angiogenesis and morphometry of bovine placentas during early gestation. Blastocysts produced in vivo were recovered from superovulated Holstein cows and served as controls. Blastocysts produced in vitro were exposed to either serum-supplemented medium with cumulus cell coculture (in vitro-produced with serum; IVPS) or modified synthetic oviductal fluid medium without serum or coculture (mSOF). Single blastocysts from each production system were transferred into heifers. Fetuses and placentas were recovered on Day 70 of gestation. Cotyledonary tissues were obtained for quantification of vascular endothelial growth factor (VEGF) and peroxisome proliferator-activated receptor-gamma (PPARG) mRNA and protein. Samples of placentomes were prepared for immunocytochemistry and histological analysis. Placentas from the mSOF group were heavier and had the fewest placentomes, least placental fluid, and lowest placental efficiency (fetal weight/placental weight) compared with the in vivo and IVPS groups. There was no effect of embryo culture system on volume densities of fetal villi or maternal endometrium within placentomes. The volume density of fetal pyknotic cells was increased in placentomes in the mSOF group compared with the in vivo and IVPS groups. Placentomes in the mSOF group had decreased densities of blood vessels and decreased levels of VEGF mRNA in cotyledonary tissue. In conclusion, compared with placentas from embryos produced in vivo or in vitro using an undefined culture system, placentas from embryos produced in vitro using a semidefined culture system exhibited a greater degree of aberrant development of the placenta during early gestation.
Farrowing induction is a common practice among swine producers to manage timing of farrowing and the labor associated with farrowing. In this experiment, the effect of induction of labor using cloprostenol on Day 114 of gestation ( = 88) was compared to our standard farrowing protocol at USMARC (natural farrowing with induction using cloprostenol on Day 116 if needed, = 82) in gilts and sows up to fourth parity. In a subset of dams ( = 10 each treatment), colostrum was collected within 30 min of birth of the first piglet, and at 4, 8, 12, and 24 h. Colostrum samples were measured for immunoglobulin G (IgG) using the immunoglobulin immunocrit and porcine IgG specific ELISA, and for total protein. Blood samples were collected from each live piglet on d 1 of age and measured using the immunocrit assay, and average immunocrit was calculated for each litter. Total piglets born and born alive, birth and weaning weights, and the stillbirth rate and preweaning mortality rate were also recorded for each litter. Results indicated that induction of farrowing by cloprostenol treatment on d 114 reduced average gestation length by 0.5 to 1 d depending on parity ( < 0.05), and reduced overall colostrum immunocrit, IgG and total protein ( < 0.05). Colostrum immunocrits and IgG concentrations were well correlated ( = 0.89; < 0.01) but IgG was curvilinearly related to total protein. Litter average immunocrits were similar in gilts between treatments, but were reduced in later parity sows induced to farrow using cloprostenol on d 114 of gestation. Total born, born alive, birth and weaning weights, and stillbirth and preweaning mortality rates were unaffected by treatments. In conclusion, induction of farrowing using cloprostenol injection on d 114 reduced colostrum IgG concentrations in dams, but this was reflected in a reduction in litter average immunocrit only in later parity sows. This reduction in litter average immunocrit was not sufficient to influence preweaning mortality, but other effects are possible given the reported influence of colostrum on growth and reproductive traits.
Abstract Varicocele, a condition of abnormally dilated veins within the pampiniform plexus, is associated with reduced male fertility in several species but its frequency and impact in rams is not well documented. Semen was collected and pampiniform plexus ultrasound performed in early December during breeding soundness examinations (BSE) of mature Composite-IV rams over a three-year study. A portion of rams were evaluated in multiple years and data from a total of 129 collections on 90 rams were available for analyses. Semen parameters were estimated by computer-assisted sperm analysis (CASA). Imaging software was used to quantify the cross-sectional area of five vessels per testis and average areas of the left testis (AAL), right testis (AAR), and both testes (AAT) were calculated. The correlation between AAL and AAR measured on the same ram within a year was moderate and positive (0.51; P < 0.001). However, correlations between AAL, AAR, and AAT measured on the same ram in consecutive years were not different from zero. Average vessel area was analyzed with fixed effects of testis side (AAL or AAR), year (2020, 2021, or 2022), ram age (2, 3, or ≥ 4 yr-old) and a random effect of ram. Across years, AAL was 23 to 25% greater than AAR and 16 to 18% greater in ≥ 4-yr-old than younger rams (P < 0.01). Unilateral varicocele (UV) was diagnosed when AAL/AAR or AAR/AAL ratio exceeded 1.5 in a ram and, for rams sampled in multiple years, those diagnosed in one year were considered affected for all subsequent years. Within year, prevalence of UV ranged from 16 to 36%. Scrotal circumference (SC) and CASA parameters were analyzed with fixed effects of year, ram age, and UV status and a random effect of ram. Within 2- and 3-yr-olds, sperm from UV rams had lower motility than unaffected rams (42.1 ± 6.7% vs 62.2 ± 4.1% and 47.8 ± 7.4% vs 70.1 ± 4.7%, respectively; P ≤ 0.02) but no differences were observed within 4-yr-old rams. Across ages, sperm from UV rams had a lower percentage of normal than unaffected rams (91.5 ± 1.1% vs 94.3 ± 0.74%; P = 0.03). Sperm concentration, progressive motility, and SC were unaffected by UV status. Future studies will evaluate the effect UV status on siring capacity. Ultrasound methodologies previously refined to diagnose varicocele in boars helped identify sub-fertile rams that would not have been classified by routine BSE procedures. However, these methodologies would benefit from concurrent machine learning and software development to ensure imaging consistency across technicians and streamline procedures for real-time decision making. USDA is an equal opportunity provider and employer.
