Time to increase in pregnancy-specific protein B following artificial insemination is a direct determinant of subsequent pregnancy loss in lactating dairy cows

Pregnancy maintenance and fetal loss assessment in Holstein cows through analyzing pregnancy-associated glycoproteins in milk

Fetal loss (FL) from the 45th day of gestation until calving can impose a significant economic burden on dairy farmers, resulting in lost profits and increased production costs. Pregnancy-associated glycoprotein (PAG) is commonly used for detecting pregnancy in cows. PAG is secreted by binucleated trophoblast cells of the placenta and regulated by more than 24 genes. The purpose of this study was to determine the PAG threshold for FL and a probability of pregnancy maintenance until calving based on milk PAG levels. Our results reveal that primiparous and multiparous cows that maintained pregnancy until the 40th week exhibited higher PAG sample-negative (SN) values in their milk in the 6th week of gestation than did those that experienced FL later in gestation. Pregnant cows with higher PAG SN values in the 6th week of gestation were more likely to maintain their pregnancies. The area under the receiver operating characteristic curve for predicting the probability of pregnancy maintenance was 0.722 for our prediction model. On the other hand, a milk PAG SN value of <0.192 indicated 95 % confidence that FL would occur between the 7th and 40th weeks of gestation. Milk PAG testing is a noninvasive sampling technique that does not induce additional stress in lactating cows. The study reveals that PAG SN values increase significantly in Holstein cows during the 6th week of gestation. The predictive model developed was effective in forecasting pregnancy outcomes up to the 40th week of gestation or calving. The model's performance is moderately good for field application and could be a useful tool for dairy producers.

Profiles of interferon-stimulated genes in multiple tissues and circulating pregnancy-associated glycoproteins and their association with pregnancy loss in dairy cows†

Pregnancy loss (PL) in lactating dairy cows disrupts reproductive and productive efficiency. We evaluated the expression of interferon-stimulated genes (ISG) in blood leukocytes, vaginal and cervical epithelial cells, luteolysis-related genes, progesterone, and pregnancy-associated glycoprotein (PAG) profiles in lactating dairy cows (n = 86) to gain insight about PL. Expression of ISG on d17, d19, and d21 was greater in cows that maintained the pregnancy (P33) compared to nonpregnant with no PL (NP). Greater ISG differences between groups were observed in the cervix (96.7-fold) than vagina (31.0-fold), and least in blood leukocytes (5.6-fold). Based on individual profiles of ISG and PAG, PL was determined to occur either before (~13%) or after (~25%) d22. For cows with PL before d22, ISG expression was similar on d17 but by d21 was lower and OXTR was greater than P33 cows and similar to NP; timing of luteolysis was similar compared to NP cows suggesting embryonic failure to promote luteal maintenance and to attach to the endometrium (no increase in PAG). For cows with PL after d22, ISG expression was similar to P33 cows on d17, d19, and d21 and luteolysis, when it occurred, was later than NP cows; delayed increase in PAG suggested later or inadequate embryonic attachment. In conclusion, PL before d22 occurred due to embryonic demise/failure to signal for luteal maintenance, as reflected in reduced ISG expression by d21. Alternatively, embryos with PL between d22 and 33 adequately signaled for luteal maintenance (ISG) but had delayed/inadequate embryonic attachment and/or inappropriate luteolysis causing PL.

Maternal blood transcriptome as a sensor of fetal organ maturation at the end of organogenesis in cattle†

Harnessing information from the maternal blood to predict fetal growth is attractive yet scarcely explored in livestock. The objectives were to determine the transcriptomic modifications in maternal blood and fetal liver, gonads, and heart according to fetal weight and to model a molecular signature based on the fetal organs allowing the prediction of fetal weight from the maternal blood transcriptome in cattle. In addition to a contemporaneous maternal blood sample, organ samples were collected from 10 male fetuses at 42 days of gestation for RNA-sequencing. Fetal weight ranged from 1.25 to 1.69 g (mean = 1.44 ± 0.15 g). Clustering data analysis revealed clusters of co-expressed genes positively correlated with fetal weight and enriching ontological terms biologically relevant for the organ. For the heart, the 1346 co-expressed genes were involved in energy generation and protein synthesis. For the gonads, the 1042 co-expressed genes enriched seminiferous tubule development. The 459 co-expressed genes identified in the liver were associated with lipid synthesis and metabolism. Finally, the cluster of 571 co-expressed genes determined in maternal blood enriched oxidative phosphorylation and thermogenesis. Next, data from the fetal organs were used to train a regression model of fetal weight, which was predicted with the maternal blood data. The best prediction was achieved when the model was trained with 35 co-expressed genes overlapping between heart and maternal blood (root-mean-square error = 0.04, R2 = 0.93). In conclusion, linking transcriptomic information from maternal blood with that from the fetal heart unveiled maternal blood as a predictor of fetal development.