Genomic Prediction for Abortion in Lactating Holstein Dairy Cows.

Abortion in dairy cattle causes great economic losses due to reduced animal health, increase in culling rates, reduction in calf production, and milk yield, among others. Although the etiology of abortions can be of various origins, previous research has shown a genetic component. The objectives of this study were to (1) describe the development of the genomic prediction for cow abortions in lactating Holstein dairy cattle based on producer-recorded data and ssGBLUP methodology and (2) evaluate the efficacy of genomic predictions for cow abortions in commercial herds of US Holstein cows using data from herds that do not contribute phenotypic information to the evaluation. We hypothesized that cows with greater genomic predictions for cow abortions (Z_Abort STA) would have a reduced incidence of abortion. Phenotypic data on abortions, pedigree, and genotypes were collected directly from commercial dairy producers upon obtaining their permission. Abortion was defined as the loss of a confirmed pregnancy after 42 and prior to 260 days of gestation, treated as a binary outcome (0, 1), and analyzed using a threshold model. Data from a different subset of animals were used to test the efficacy of the prediction. The additive genetic variance for the cow abortion trait (Z_Abort) was 0.1235 and heritability was 0.0773. For all animals with genotypes (n = 1,662,251), mean reliability was 42%, and genomic predicted transmitting abilities (gPTAs) ranged from −8.8 to 12.4. Z_Abort had a positive correlation with cow and calf health traits and reproductive traits, and a negative correlation with production traits. Z_Abort effectively identified cows with a greater or lesser risk of abortion (16.6% vs. 11.0% for the worst and best genomics groups, respectively; p < 0.0001). The inclusion of cow abortion genomic predictions in a multi-trait selection index would allow dairy producers and consultants to reduce the incidence of abortion and to select high-producing, healthier, and more profitable cows.

Relationship of molecular breeding value for beef tenderness with heifer traits through weaning of their first calf.

Polymorphisms in µ-calpain (CAPN1) that beneficially associate with beef tenderness are reported to antagonistically associate with calving day in beef heifers and post-partum interval to estrus in beef cows. We, therefore, hypothesized that a molecular breeding value for slice shear force, calculated based on CAPN1 and calpastatin (CAST) genotypes, would demonstrate an antagonistic relationship between genomically predicted slice shear force and ordinal calving date in replacement beef heifers. A secondary objective of this study was to evaluate the association of a polymorphism in diacylglycerol O-acyltransferase (DGAT1) with reproductive traits in beef heifers. One hundred eighty-seven MARC III heifers (» Angus, » Hereford, » Red Poll, and » Pinzgauer) that had been selectively bred to increase the frequency of these polymorphisms were submitted for monthly ultrasound exams beginning at 333 d of age and continuing until the start of breeding to determine pubertal status. At the last exam before breeding, all antral follicles were counted, and the length and height of each ovary was measured to determine if genomic selection for slice shear force associated with ovarian follicle number. Calving date, calf gender, and calf birth weight were recorded at parturition. Regression analysis of the molecular breeding value for slice shear force of the heifers on ordinal calving date indicated no association between genomic prediction of tenderness and calving date (P = 0.16); however, there was a tendency for age at puberty to be delayed in heifers as genetic merit for tenderness improved (P = 0.09). The results of the present study indicate that within experimental precision, selecting for tenderness using genomic predictions had minimal or no antagonistic association with reproductive performance in heifers. Further analysis of reproductive performance as cows is needed within this population but applying these genetic markers to select for tenderness in steers does not antagonize reproductive traits influencing conception or first calf birth date and birth weight in replacement beef heifers.

Genomic Prediction for Twin Pregnancies.

Twinning is a multifactorial trait influenced by both genetic and environmental factors that can negatively impact animal welfare and economic sustainability on commercial dairy operations. To date, using genetic selection as a tool for reducing twinning rates on commercial dairies has been proposed, but not yet implemented. In response to this market need, Zoetis (Kalamazoo, MI, USA) has developed a genomic prediction for twin pregnancies, and included it in a comprehensive multitrait selection index. The objectives of this study were to (1) describe a genetic evaluation for twinning in Holstein cattle, (2) demonstrate the efficacy of the predictions, (3) propose strategies to reduce twin pregnancies using this information. Data were retrieved from commercial dairies and provided directly by producers upon obtaining their permission. The twin pregnancies trait (TWIN) was defined as a pregnancy resulting in birth or abortion of twin calves, classified as a binary (0,1) event, and analysed using a threshold animal model. Predictions for a subset of cows were compared to their on-farm twin records. The heritability for twin pregnancies was 0.088, and genomic predicted transmitting abilities ((g)PTAs) ranged from -7.45-20.79. Genetic correlations between TWIN and other traits were low, meaning that improvement for TWIN will not negatively impact improvement for other traits. TWIN was effectively demonstrated to identify cows most and least likely to experience a twin pregnancy in a given lactation, regardless of reproductive protocol used. Effective inclusion of the prediction in a multitrait selection index offers producers a comprehensive tool to inform selection and management decisions. When combined with sound management practices, this presents a compelling opportunity for dairy producers to proactively reduce the incidence of twin pregnancies on commercial dairy operations.

Vascular endothelial growth factor A isoforms modulate follicle development in peripubertal heifers independent of diet through diverse signal transduction pathways.

Follicular progression during peripuberty is affected by diet. Vascular endothelial growth factor A (VEGFA) induces follicle progression in many species; however, there are limited studies to determine if diet may alter the effects of angiogenic VEGFA165-stimulated follicle progression or antiangiogenic VEGFA165b follicle arrest. We hypothesized that diet affects the magnitude of angiogenic and antiangiogenic VEGFA isoform actions on follicular development through diverse signal transduction pathways. To test this hypothesis, beef heifers in our first trial received Stair-Step (restricted and refeeding) or control diets from 8 to 13 months of age. Ovaries were collected to determine follicle stages, measure vascular gene expression and conduct ovarian cortical cultures. Ovarian cortical cultures were treated with phosphate-buffered saline (control), 50 ng/ml VEGFA165, VEGFA165b, or VEGFA165 + VEGFA165b. The Stair-Step heifers had more primordial follicles (P < 0.0001), greater messenger RNA abundance of vascular markers VE-cadherin (P < 0.0001) and NRP-1 (P < 0.0051) than controls at 13 months of age prior to culture. After culture, VEGFA isoforms had similar effects, independent of diet, where VEGFA165 stimulated and VEGFA165b inhibited VEGFA165-stimulated follicle progression from early primary to antral follicle stages. In vitro cultures were treated with VEGFA isoforms and signal transduction array plates were evaluated. VEGFA165 stimulated expression of genes related to cell cycle, cell proliferation, and growth while VEGFA165b inhibited expression of those genes. Thus, VEGFA isoforms can act independently of diet to alter follicle progression or arrest. Furthermore, follicle progression can be stimulated by VEGFA165 and inhibited by VEGFA165b through diverse signal transduction pathways.

Brangus cows have ovarian reserve parameters more like Brahman than Angus cows.

Bos indicus females have more surface antral follicles than Bos taurus females; however, histological studies demonstrated no difference in total number of primordial follicles between these two biological types of cattle. Primordial follicle density in the ovary was less in Nelore ovaries compared to Angus ovaries, but no studies have examined the primordial follicle density in Bos indicus cross-bred females. It, therefore, was hypothesized that primordial follicle density in the ovary would decrease as percentage Bos indicus increased. Ovaries were collected from cross-bred Angus (n = 32, no Bos indicus influence), Brangus (n = 15), or Brahman (n = 9) cows and prepared for histological evaluation. There was no difference in total number of primordial follicles per ovary between breeds (P > 0.10). When numbers of primordial follicles were expressed on a per gram of ovarian tissue basis, there were fewer primordial follicles per gram of ovarian tissue in Brangus and Brahman cows than in Angus cows (P < 0.05). Brangus cows did not differ from Brahman cows in primordial follicle density (P > 0.10). Differences in primordial follicle density could indicate differences in capacity of ovarian stroma to produce factors necessary for oogonial proliferation and primordial follicle formation among breeds. Identifying these factors could improve the aprroach for culturing pre-antral follicles of cattle. Furthermore, these results explain why ultrasonographic antral follicle counts may need to be adjusted to a greater threshold to predict size of the ovarian reserve and determine ovarian reserve related reproductive traits in Bos indicus females.

Maternal age influences the number of primordial follicles in the ovaries of yearling Angus heifers.

The number of antral follicles detectable by ultrasonography in heifers is influenced by age of the dam, because daughters of primiparous cows have fewer antral follicles than daughters of mature cows. We, therefore, hypothesized that heifers with primiparous dams would have fewer primordial follicles in their ovaries than heifers born to mature (4+ y) cows. Angus heifers (n = 464) were submitted for ultrasonographic evaluation of antral follicle number at 325, 355, and 385 d of age. Ovaries were collected from a random subset of heifers (n = 79) and processed for histological evaluation to determine number of primordial follicles. A greater percentage of heifers with primiparous dams had a corpus luteum at first ultrasonographic examination; however, a greater percentage of heifers with multiparous dams had ovulated by the start of breeding (P < 0.01). Heifers with primiparous dams had fewer antral follicles detectable by ultrasonography (P < 0.01). Heifers with primparous dams had fewer surface antral follicles on their ovaries (P < 0.01), and the number of primordial follicles per histological section was less for heifers with primiparous dams (P = 0.02). These data indicate that the lesser number of antral follicles detectable by ultrasonography in heifers with primparous dams is due to less ovarian follicle reserves. Selecting replacement heifers from mature dams may result in daughters with greater fertility and reproductive longevity; however, further research is necessary to determine if interactions between size of the ovarian follicle reserve and age at puberty influence fertility and reproductive longevity in replacement heifers.

Effects of preovulatory estradiol on uterine environment and conceptus survival from fertilization to maternal recognition of pregnancy.

Preovulatory estradiol is known to impact embryo quality and survival. The objective of this study was to determine the effects of preovulatory estradiol on the uterine environment and conceptus survival through maternal recognition of pregnancy. Beef cows/heifers were AIed following induced ovulation. Cows were grouped into high and low preovulatory estradiol. Conceptuses were collected on day 16 nonsurgically (Rep 1; n = 20), or following slaughter (Rep 2; n = 29). Blood was collected to determine plasma glucose concentrations, and uterine luminal fluid (ULF) was analyzed for protein, glucose, and interferon tau (IFNT) concentrations. Total cellular RNA was extracted from caruncular (CAR) and intercaruncular (INCAR) endometrial tissue. There was no effect of preovulatory estradiol on conceptus recovery rate (P = 0.38) or on apoptosis rate in the trophectoderm (P = 0.64). Cows in which a conceptus was recovered had greater concentrations of protein in the ULF (P = 0.04). Animals with elevated preovulatory estradiol had greater endometrial abundance of SLC2A1 (P = 0.05) and SLC5A1 (P = 0.04) in both INCAR and CAR tissue. Presence of a conceptus also tended to increase (P = 0.10) abundance of SLC5A1 in INCAR. In CAR tissue, cows with a conceptus had decreased SLC2A4 abundance (P = 0.05). In summary, conceptus recovery rates, apoptosis in the trophectoderm, IFNT, glucose, and protein concentration in ULF did not differ between cows that did or did not have an increase in preovulatory estradiol concentrations. Thus, there is no indication of increased conceptus survival to day 16 of pregnancy based on estradiol concentrations.

µ-Calpain (CAPN1), calpastatin (CAST), and growth hormone receptor (GHR) genetic effects on Angus beef heifer performance traits and reproduction.

Genetic marker effects and type of inheritance are estimated with poor precision when minor marker allele frequencies are low. An Angus population was subjected to marker assisted selection for multiple years to equalize CAPN1 haplotypes, CAST, and GHR genetic marker frequencies. The objective was to estimate the pleiotropic effects of these carcass quality oriented markers for body weight, reproduction, and first calf performance traits in 174 replacement beef females which were managed under 2 post-weaning development protocols. Heifers were weighed at 11-, 12-, and 13-mo, at first breeding season pregnancy evaluation, and prior to first calving season. Pubertal status was determined at 11-, 12-, and 13-mo of age. Antral follicles were counted, reproductive tracts were scored, and tract dimensions were measured at 13-mo. Body condition and hip height were scored and measured at pregnancy evaluation and prior to calving season. Heifer pregnancy and weaning rates and ordinal birth date were recorded. Calf body weights at birth and weaning were analyzed. Single df linear contrasts for recessive effects of the GHR heterozygous genotype showed significant decreases of 2.5-3.6% in 11-, 12-, and 13-mo heifer body weights and heifer weight prior to calving. The additive differences between GHR homozygotes were small and not significant for all body weights measured but a 1 wk difference in calf birth date was significant. For all 13-mo uterine measurements, scores, and antral follicle counts, only the CAST dominance contrast for medium antral follicle count was significant. The CAPN1 haplotype with a strong additive effect for increased beef tenderness also had a significant additive effect on calving date. Heifers homozygous for the tender haplotype calved 7.9 days later than heifers homozygous for the tough haplotype. Most heifer reproductive traits were not significantly affected by CAST and CAPN1 markers that are widely used to improve beef tenderness by selection and breeders should not be concerned with how these markers affect reproduction and other heifer traits with the possible exception of CAPN1 effects on calving date.

Validation of genomic predictions for wellness traits in US Holstein cows.

The objective of this study was to evaluate the efficacy of wellness trait genetic predictions in commercial herds of US Holstein cows from herds that do not contribute phenotypic information to the evaluation. Tissue samples for DNA extraction were collected from more than 3,400 randomly selected pregnant Holstein females in 11 herds and 2 age groups (69% nulliparous, 31% primiparous) approximately 30 to 60 d before their expected calving date. Lactation records from cows that calved between September 1, 2015, and December 31, 2015, were included in the analysis. Genomically enhanced predicted transmitting abilities for the wellness traits of retained placenta, metritis, ketosis, displaced abomasum, mastitis, and lameness were estimated by the Zoetis genetic evaluation and converted into standardized transmitting abilities. Mean reliabilities of the animals in the study ranged between 45 and 47% for each of the 6 traits. Animals were ranked by their standardized transmitting abilities within herd and age group then assigned to 1 of 4 groups of percentile-based genetic groups of equal size. Adverse health events, including retained placenta, metritis, ketosis, displaced abomasum, mastitis, and lameness, were collected from on-farm herd management software, and animal phenotype was coded as either healthy (0), diseased (1), or excluded for each of the 6 outcomes of interest. Statistical analysis was performed using a generalized linear mixed model with genetic group, age group, and lactation as fixed effects, whereas herd and animal nested within herd were set as random effects. Results of the analysis indicated that the wellness trait predictions were associated with differences in phenotypic disease incidence between the worst and best genetic groups. The difference between the worst and best genetic groups in recorded disease incidence was 2.9% for retained placenta, 10.8% for metritis, 1.1% for displaced abomasum, 1.7% for ketosis, 7.4% for mastitis, and 3.9% for lameness. Odds ratio estimates between the highest and lowest genetic groups ranged from 1.6 (lameness) to 17.1 (displaced abomasum) for the 6 traits analyzed. These results indicate that wellness trait information of young calves and heifers can be used to effectively predict meaningful differences in future health performance. Improving wellness traits through direct genetic selection presents a compelling opportunity for dairy producers to help reduce disease incidence and improve profitability when coupled with sound management practices.

Timing of transcriptomic and proteomic changes in the bovine placentome after parturition.

Proper post-partum reproductive performance is important for reproductive efficiency in beef cows, and dystocia decreases post-partum fertility. Crossbred beef cows (n = 1676) were evaluated for lifetime performance based on degree of dystocia at presentation of the first calf. Cows that experienced moderate or severe dystocia produced fewer calves during their productive life (P < 0.01). The exact mechanism is unclear, but may be due to the contributions of dystocia to abnormal placental separation. Proteolytic activity is hypothesized to contribute to placental separation in ruminants; however, when ovine placentomes were collected following caesarian section, no proteolytic activity was detected. We hypothesized that stage 2 of parturition was necessary to stimulate proteolysis and initiate placental separation. Serial placentome collections were performed on mature cows (n = 21 initiated; 7 with complete sampling) at hourly intervals for the first 2 h after expulsion of the calf. An intact piece of each placentome was fixed for histological evaluation, and a separate piece of caruncular and cotyledonary tissue from each placentome was frozen for transcriptomic and proteolytic analysis. A full set of placentomes was collected from only 7 of 21 cows at 0, 1, and 2 h, and all cows had expelled fetal membranes by 6 h. Histological, transcriptomic and proteolytic analysis was performed on placentomes from cows from which three placentomes were collected (n = 7). The microscopic distance between maternal and fetal tissues increased at 1 h (P = 0.01). Relative transcript abundance of matrix metalloprotease 14 (MMP14) tended to increase with time (P = 0.06). The relative transcript abundance of plasminogen activator urokinase-type (PLAU) was greater in caruncles than cotyledons (P = 0.01), and tended (P = 0.10) to increase in the caruncle between 0 and 2 h while remaining unchanged in the cotyledon over the same span of time. Greater PLAU and plasminogen activator tissue-type (PLAT) proteolytic activity was detected by zymography in the caruncle than the cotyledon immediately post-partum (P < 0.01). From these findings we conclude that 1) dystocia during the first parity decreases lifetime productivity in beef cattle, 2) the PA system is present at both the transcript and protein level in the bovine plactentome during parturition and 3) proteolytic activity is localized to the caruncular aspect of the placentome.

Beef heifers with diminished numbers of antral follicles have decreased uterine protein concentrations.

Previous research demonstrated a favorable relationship between the number of follicles detectable in the bovine ovary by ultrasonography and fertility, and bovine females with diminished numbers of antral follicles had smaller reproductive tracts. Therefore, we hypothesized that uterine function would be compromised in beef heifers with diminished numbers of antral follilcles. Angus heifers (n=480) were submitted for ultrasonographic evaluation of antral follicle number at 325 and 355d of age. After the second ultrasonographic examination, 40 pubertal heifers with the greatest average number of antral follicles (30.9±0.7) and 40 pubertal heifers with the lowest average number of antral follicles (14.2±0.7) were synchronized with two i.m. injections of prostaglandin F2α (25mg) administered 11d apart, and heifers were slaughtered on d6 (n=26 heifers/group) or d16 (n=14 heifers/group) of the resultant estrous cycle. The uterus was weighed, flushed for determination of protein content, and representative samples were fixed for determination of endometrial gland morphometry. Heifers in the Low group had fewer surface antral follicles and smaller reproductive tracts than heifers in the High group (P<0.01). Protein content of the uterine flushes was decreased in heifers in the Low group (P<0.01); however, there was no difference in the percent area of the endometrium occupied by endometrial glands. From these results, we conclude that the uterine environment of beef heifers with diminished numbers of antral follicles is less conducive to supporting early embryonic survival.

Uterine environment and pregnancy rate of heifers with elevated plasma urea nitrogen.

Diets high in protein are associated with lower reproductive performance and changes in the uterine environment. The objective of this study was to determine the effect of elevated systemic concentrations of urea nitrogen on the uterine environment and pregnancy success in beef heifers. Heifers (n=150) were matched by breed, age, and body weight then randomly assigned to one of two dietary treatments: 1) Control (10% CP) or 2) High protein (14% CP) over three replicates (n=40/replicate). Estrus was synchronized with an injection of PGF2α. Uterine pH, plasma urea nitrogen (PUN), ammonia, and glucose concentrations were determined on d 7 of the estrous cycle. Pregnancy status was determined by ultrasonography 30 d following the breeding season. In vitro fertilization was performed on heifers precluded from uterine analysis (n=15/diet) to determine the effect of a High Protein diet on oocyte quality. Plasma urea concentrations were greater in the High Protein diet compared to Control (P<0.001). There was no effect of diet on plasma ammonia (P=0.12), plasma glucose (P=0.40), uterine pH (P=0.67), interval to estrus (P=0.54), duration of estrus (P=0.38), or pregnancy rate (P=0.83). There was no effect of diet (P>0.40) on the number of oocytes collected, number of oocytes cleaved, amount of blastocysts, percentage of oocytes cleaved and percentage of blastocysts present. In summary, high nitrogen diets increased PUN concentrations in heifers; however, there were no deleterious effects on reproduction.

Age and Nursing Affect the Neonatal Porcine Uterine Transcriptome.

The lactocrine hypothesis for maternal programming of neonatal development was proposed to describe a mechanism through which milk-borne bioactive factors, delivered from mother to nursing offspring, could affect development of tissues, including the uterus. Porcine uterine development, initiated before birth, is completed postnatally. However, age- and lactocrine-sensitive elements of the neonatal porcine uterine developmental program are undefined. Here, effects of age and nursing on the uterine transcriptome for 48 h from birth (Postnatal Day [PND] = 0) were identified using RNA sequencing (RNAseq). Uterine tissues were obtained from neonatal gilts (n = 4 per group) within 1 h of birth and before feeding (PND 0), or 48 h after nursing ad libitum (PND 2N) or feeding a commercial milk replacer (PND 2R). RNAseq analysis revealed differentially expressed genes (DEGs) associated with both age (PND 2N vs. PND 0; 3283 DEGs) and nursing on PND 2 (PND 2N vs PND 2R; 896 DEGs). Expression of selected uterine genes was validated using quantitative real-time PCR. Bioinformatic analyses revealed multiple biological processes enriched in response to both age and nursing, including cell adhesion, morphogenesis, and cell-cell signaling. Age-sensitive pathways also included estrogen receptor-alpha and hedgehog signaling cascades. Lactocrine-sensitive processes in nursed gilts included those involved in response to wounding, the plasminogen activator network and coagulation. Overall, RNAseq analysis revealed comprehensive age- and nursing-related transcriptomic differences in the neonatal porcine uterus and identified novel pathways and biological processes regulating uterine development.

Influence of puberty and antral follicle count on calving day in crossbred beef heifers.

Lifetime productivity and longevity are greater in beef cows that give birth early in their first calving season. The ability of heifers to conceive early in the breeding season is traditionally thought to be a function of pubertal status; however, recent evidence suggests that antral follicle count is positively associated with calving day in pubertal beef heifers. Additionally, there is evidence to suggest that the total number of ovarian follicles may alter response to hormonal synchronization protocols. The objectives of this study were to confirm the beneficial influence of antral follicle count on calving day in beef heifers and to determine whether response to PGF2α is associated with differences in antral follicle counts. A 2 × 2 factorial experiment was designed to investigate the interaction between calving period (early vs. late) and PGF2α (control vs. PGF) on calving day and antral follicle count in yearling beef heifers (n = 95). As intended, calving day was less in the early calving period compared to the late calving period (P < 0.01). There were no differences in calving day in response to treatment with PGF2α (P > 0.05). There was a significant interaction between calving period and PGF2α on age at first calving (P < 0.01), such that heifers treated with PGF2α that gave birth early were younger than heifers treated with saline that gave birth early. Calf weaning weights were greater in the early calving group than in the late calving group (P < 0.01). Heifers that gave birth in the early calving group possessed more antral follicles at prebreeding ultrasonographic examination than heifers that gave birth in the late calving group (P = 0.05). These findings confirm that antral follicle counts are associated with calving day in pubertal beef heifers. The use of antral follicle counts as a prebreeding phenotype provides additional utility to reproductive tract scoring for commercial production because of its association with calving day. As a prebreeding ovarian phenotype, antral follicle counts may hold additional applicability for organic beef producers looking to reduce the length of their calving season without increasing the total number of replacement heifers retained.

Placental accommodations for transport and metabolism during intra-uterine crowding in pigs.

Litter size and birth weights are limited by uterine capacity, defined as the ability of the uterus to maintain the appropriate development of some number of conceptuses. Uterine capacity is the result of the combined effects of uterine, placental and embryo/fetal function. The number of living conceptuses that the uterus is capable of supporting is greater during early gestation compared to later gestation. Plots of log fetal weight versus log placental weight also indicate that fetal weights are less sensitive to reduced placental weight (and therefore reduced intrauterine space) in early gestation compared to late gestation. However, even in late gestation, mechanisms still exist that maintain fetal growth when the size of the placenta is reduced. One such mechanism is likely to be improved development of the folded placental-epithelial/maternal-epithelial bilayer. Fold depth, and therefore the maternal fetal interactive surface, increases as gestation advances and is greater in placenta from small fetuses. On the fetal side of the placenta, the epithelial bilayer is embedded in stromal tissue. Glycosaminoglycans are major components of stroma, including hyaluronan and heparan sulfate. Hyaluronidases and heparanases are present within placental tissues, and likely play roles in modification of stromal components to facilitate fold development. Glycosaminoglycans are polymers of forms of glucose (glucosamine, glucuronic acid, iduronic acid) suggesting that glycosaminoglycan synthesis may compete with the glucose needs of the developing fetus. Pig conceptuses are fructogenic, such that a substantial portion of glucose transferred from mother to fetus is converted to fructose. Fructose is an intermediate product in the synthesis of glucosamine from glucose, and glucosamine is linked to regulation of trophoblast cell proliferation through regulation of mTOR. These findings suggest a link between glucose, fructose, glucosamine synthesis, GAG production, and placental morphogenesis, but the details of these interactions remain unclear. In addition, recent placental epithelial transcriptome analysis identified several glucose, amino acid, lipid, vitamin, mineral and hormone transporter mechanisms within the placenta. Further elucidation of mechanisms of placental morphogenesis and solute transport could provide clues to improving nutrient transport to the pig fetus, potentially increasing litter size and piglet birth weights.

The plasminogen activator system in the ovine placentome during late gestation and stage-two of parturition.

The process of placental separation is not completely understood. In domestic animals, especially cattle, it is important that expulsion of the fetal membranes takes place in a timely manner in order to achieve maximal reproductive efficiency. The activity of the matrix-metalloprotease (MMP) family of proteases is known to be reduced in placentomes from cases of retained placenta. Members of the MMP family are known to be activated by the plasminogen activator (PA) family of proteases. We hypothesized that the expression and activity of the PA family increase in the cotyledon and/or caruncle as parturition approaches, with maximal expression and activity at parturition. To test this hypothesis, we performed reverse-transcriptase quantitative PCR and plasminogen-casein zymography to detect the presence and activity of PA family members in the placentome leading up to and during parturition in spontaneous and dexamethasone-induced parturient ewes. The results from our experiments indicated that serine proteases inhibitor E1 (SERPINE1) mRNA abundance in the cotyledon was different between treatment groups (P = 0.0002). In the caruncle, gene expression for plasminogen activator urokinase-type (PLAU) was different (P = 0.0154), and there was a strong trend for differences in SERPINE1 expression (P = 0.0565). These results demonstrate that expression of the PA system in the placentome changes from late pregnancy to parturition, and the presence or activity of these enzymes may occur after fetal expulsion.

Technical report: serial collections of placentomes during parturition in cattle and subsequent reproductive performance.

Placental separation is a complex physiological event in reproductive physiology and the underlying molecular mechanisms remain unclear. When comparing different experiments the timing of tissue collections is a significant consideration due to the variability in time between fetal expulsion and expulsion of the placenta (30 min to >24 h). This makes comparison of tissues samples across animals difficult and supports the need for serial tissue collections within animal. Additionally, the instrument most commonly used, a modified Richter-Resinsinger effeminator, for placentome collections is difficult to obtain and there are no data in the literature record regarding subsequent reproductive performance of animals subjected placentome collections. To facilitate continued research into the physiology behind placental separation, we designed an instrument from readily available components and performed serial transvaginal placentome collections in cattle. Three placentomes at 2-h intervals were collected after expulsion of the calf in 18 multiparous cows. There was no incidence of mortality and all cows resumed estrous after the procedure. Neither time from placentome collection nor age had a significant effect on pregnancy status at diagnosis (P > 0.05). These results demonstrate the viability of and utility of this device for collecting multiple placentomes in cattle.