Trophoblast differentiation and embryonic development are delayed in lactating cows compared to nulliparous heifers.

Effect of manipulating progesterone before timed artificial insemination on reproductive and endocrine outcomes in high-producing multiparous Holstein cows

Differences in placental mass and vascularity exist between cows gestating single vs. multiple fetuses. Therefore, the association between fetal number and placental development or function was assessed by comparing concentrations of vascular endothelial growth factor (VEGF), pregnancy-associated glycoproteins (PAG), IGF-I, and progesterone in the maternal blood of cattle selected for twin births and gestating 1 (n = 23) vs. 2 (n = 17) fetuses. Samples of jugular venous blood were collected serially at a mean of 57, 121, 192, and 234 d (range within groups was 20 d) after AI. Plasma concentrations of VEGF, IGF-I, and progesterone were measured by double-antibody RIA, and of PAG by an indirect sandwich ELISA. Concentrations of VEGF and progesterone were greater (P < 0.05) in dams with twin vs. single fetuses. Maternal VEGF concentrations did not differ among collection times, but progesterone concentrations increased (P < 0.01) between d 192 and 234. Conversely, PAG concentrations were low at d 57 and 121 and did not differ between dams carrying singles or twins. However, the subsequent increase (P < 0.01) in PAG was greater in dams with twins, resulting in greater (P < 0.01) PAG concentrations for dams with twins at d 192 and 234 (type of birth x time; P < 0.01). Maternal IGF-I concentrations were unaffected by fetal number. Because corpora lutea persisted for the duration of the evaluation period, maternal progesterone concentrations were likely related to the number of corpora lutea rather than the number of fetuses. It is postulated that the greater PAG and VEGF concentrations in the blood of dams gestating twins are the result of a larger uteroplacental mass, including increased numbers of binucleate cells and increased angiogenesis and vasculogenesis associated with a twin pregnancy. Although PAG and VEGF were elevated in dams gestating twins, variability within and among birth groups limits the use of PAG or VEGF measurements for the diagnosis of twins.

Early embryo losses, progesterone and pregnancy associated glycoproteins levels during summer heat stress in dairy cows.

Plasma concentrations of pregnancy-associated glycoprotein-1 (PAG-1) in high producing dairy cows suffering early fetal loss during the warm season

Pregnancy-associated glycoprotein and progesterone profiles during pregnancy and postpartum in native goats from the north-east of Brazil

Post-ovulatory supplementation of progesterone (P4) to cows has been associated with enhanced conceptus elongation. The aim of the present study was to investigate the impact of P4 supplementation on peri-implantation conceptus signaling including the secretion of interferon tau (IFNT), the maternal response to IFNT (mRNA abundance of interferon-stimulated genes [ISG; ISG15 and MX2]), and circulating pregnancy-associated glycoproteins (PAG). Two cohorts (A and B) of primiparous Angus beef cows were synchronized to estrus, artificially inseminated (d0), and assigned randomly to receive intravaginal P4 device (CIDR, 1.38 mg) from d3 to d12 or remain as untreated controls. Blood and cervical cytobrush were collected from d3 to d24 and a uterine cytobrush was collected on d24 from Cohort A to assess circulating concentrations of P4, PAG, mRNA abundance of ISG, and concentrations of IFNT, respectively. Blood and cytobrush (cervical and uterine) were collected from Cohort B on d18 to assess circulating concentrations of P4, mRNA abundance of ISG, and concentrations of IFNT, respectively. The mRNA abundance of ISG was assessed in luteal biopsies on d18 and d22. There was no effect of P4 supplementation on concentrations of IFNT in the uterus on d18. There was no effect of supplemental P4 on mRNA abundance or timing of ISG in endometrial, cervical, or luteal tissue. The earlier detection of PAG in circulation and lower uterine fluid concentrations of IFNT on d24 in P4-supplemented cows suggests advanced trophoblast differentiation and enhanced conceptus development beyond previously reported advances in conceptus elongation alone.

This study presents serum concentrations of pregnancy-associated glycoprotein (PAG), oestrone sulphate (E1-S) and progesterone (P4), and the effects of some dam and foetus-related factors on these profiles during gestation in Borana and crossbred cattle. The PAG concentrations at 4th week post-conception ranged from 1.5-5.5 and 2.1-4.7 ng/ml in Borana (n = 6) and crossbred (n = 8) cattle, respectively. The mean PAG concentrations increased progressively from 4th to 33rd week of gestation (from 3.3-173 ng/ml for Borana and 4.2-240 ng/ml for crossbred cattle) and reached peak around calving. Breed, parity status, dam body weight, foetal sex and foetal birth weight significantly influenced the PAG concentrations. After delivery, the PAG concentrations declined steadily to 5.7 ng/ml in Borana (n = 7) and 3.9 ng/ml in crossbred (n = 6) cattle 10 weeks post-partum. The serum E1-S concentrations at 17th week of pregnancy ranged from 0.3-2.6 and 0.9-5.7 ng/ml in Borana (n = 8) and crossbred (n = 9) cattle, respectively. The mean E1-S concentrations increased progressively from 17th to 33rd week of gestation (from 1.1-4.6 ng/ml for Borana and 2.7-10.8 ng/ml for crossbred). Breed, parity status, dam body weight and foetal sex significantly influenced E1-S concentrations. The P4 concentrations at 4th week of pregnancy ranged from 3.2-5.1 and 1.7-8.9 ng/ml in Borana (n = 6) and crossbred (n = 8) cattle, respectively. The P4 level remained elevated throughout pregnancy. This study indicated that the serum PAG and P4 concentrations at 4th and E1-S approximately 17th week of pregnancy were above the cut-off value for pregnancy test and the hormonal profiles observed were comparable to the previous reports. Furthermore, the PAG and E1-S profiles were considerably influenced by factors such as breed, weight and parity status of the dam, and foetal sex and foetal birth weight (only PAG).

Characteristics and retention of luteal structures, extended postinsemination cycle, progesterone, and pregnancy-specific protein B in serum after human chorionic gonadotropin treatment of dairy cows

Holstein (HO) calves, 3-breed crossbred calves of Montbéliarde, Viking Red, and HO (MVH), and 3-breed crossbred calves of Normande, Jersey, and Viking Red (NJV) were compared for gestation length (GL), calf weight at birth (CW), calving difficulty (CD), and stillbirth (SB) in 2 research herds at the University of Minnesota. Calves were born from January 2009 to December 2019. For the St. Paul and Morris herds, HO calves (n = 1,121) were compared with MVH calves (n = 1,393) from primiparous and multiparous cows. For the single herd analysis at Morris, HO calves (n = 476), MVH calves (n = 922), and NJV calves (n = 405) were compared from primiparous and multiparous cows. Primiparous and multiparous births were analyzed separately because multiparous cows had multiple births, and CD and SB are likely different traits for primiparous and multiparous cows. Statistical analysis of GL, CW, CD, and SB included fixed effects of sex of calf, herd, breed group of calf, and year-season of calving. For the St. Paul and Morris herds, HO calves from primiparous (278 d) and multiparous (279 d) HO cows had shorter GL compared with MVH calves from primiparous (280 d) and multiparous (282 d) crossbred cows. The HO calves (39.4 and 43.2 kg, respectively) from primiparous and multiparous HO cows had lower CW compared with MVH calves (40.3 and 44.3 kg, respectively) from primiparous and multiparous crossbred cows. Calving difficulty and SB were not different for HO and MVH calves from primiparous and multiparous cows. For the single herd analysis at Morris, HO calves (278 and 279 d, respectively) from primiparous and multiparous HO cows had shorter GL compared with MVH calves (281 and 282 d, respectively) and NJV calves (282 and 282 d, respectively) from primiparous and multiparous crossbred cows. The CW of HO calves (38.6 and 42.0 kg, respectively) from primiparous and multiparous HO cows was lower compared with MVH calves (39.7 and 42.9 kg, respectively), but higher compared with NJV calves (35.1 and 38.0 kg, respectively) from primiparous and multiparous crossbred cows. Calving difficulty and SB did not differ for HO, MVH, and NJV calves from primiparous and multiparous cows. The longer GL for crossbred calves and higher CW for MVH calves did not increase CD and SB for primiparous and multiparous cows. Dairy producers may implement 3-breed rotational crossbreeding systems that include the HO, Jersey, Normande, Montbéliarde, and Viking Red breeds, and some breeds may increase GL and CW without an increase in CD and SB.

Effects of crossbreeding on endocrine patterns determined in pregnant beef/dairy cows naturally infected with Neospora caninum

Three-breed rotational crossbreds of Montbéliarde, Viking Red, and Holstein compared with Holstein cows for feed efficiency, income over feed cost, and residual feed intake

The Concentration of Progesterone in the Milk of Cows During the Reproductive Cycle

Effects of oral calcium supplementation on productive and reproductive performance in Holstein cows.

Nulliparous heifers (n = 58) were studied to determine whether computer-assisted quantitative echotexture analysis of ultrasound images reflects the functional and histomorphological characteristics of the corpus luteum. The ovaries of heifers were examined daily by transrectal ultrasonography from day -2 (day 0 = ovulation) until the day of ovariectomy during metoestrus (day 3; n = 8), early dioestrus (day 6; n = 9), mid-dioestrus (mean, day 10; n = 7), or pro-oestrus (mean, day 18; n = 8; Expt 1). High resolution ultrasound images of corpora lutea were obtained in vitro, and were digitized and analysed using custom-developed computer algorithms optimized for ultrasonography. Cryostat sections of corpora lutea were examined for lipid distribution, and corpora lutea were homogenized to determine the content of progesterone, total protein, cholesterol and triglyceride. In Expt 2, heifers (n = 26) were ovariectomized as in Expt 1, and ovaries were prepared for histomorphometric evaluation. Pixel values (brightness of picture elements) of ultrasound images of corpora lutea were characterized as high during metoestrus, low during early and mid-dioestrus, and increasing again during pro-oestrus (P < 0.05). Changes (P < 0.001) in volume density of luteal cells were characterized as increasing from metoestrus (40.7 +/- 0.4%) to mid-dioestrus (55.8 +/- 2.8%) and decreasing again at pro-oestrus (41.5 +/- 0.9%). The proportion of blood vascular components decreased (P < 0.001) progressively from 31.0 +/- 1.0% in metoestrus to 15.6 +/- 1.1% in pro-oestrus. Pixel values of ultrasound images of corpora lutea were correlated with luteal (r = -0.72, P < 0.05) and plasma (r = -0.71, P < 0.03) progesterone concentration, and to the volume densities of luteal cells (r = -0.75, P < 0.02) and connective tissue (r = 0.69, P < 0.03). Estimates of triglyceride, protein and cholesterol content of corpora lutea were not correlated with pixel values of ultrasound images. Protein and cholesterol content did not change while triglyceride concentration increased during pro-oestrus (P < 0.05). Results support the hypothesis that ultrasound images reflect luteal and plasma progesterone content, and histomorphological characteristics of the corpus luteum.

Short communication: Field evaluation of a pregnancy confirmation test using milk samples in dairy cows