Non-pregnant Cows Research Articles

EFFECT OF STIMULIN-VET ON THE COWS PREGNANCY CONSOLIDATION AFTER INSEMINATION

Improving the reproductive performance of cattle is one of the main tasks in livestock. Numerous stressors, high productivity, poor feeding, improper conditions of care and operation cause hormonal changes in the system "hypothalamus-pituitary-ovaries" of females, which negatively affects reproduction. As a result, farms do not receive a certain amount of offspring and milk, and in the future - an increase in the infertility rate of uterine cattle. In cows after calving at the initial stage of lactation, the trophic function of the pituitary gland is more aimed at ensuring the secretion of milk than at restoring the cyclic activity of the ovaries. Therefore, to correct the reproductive capacity of cows use: feed additives, hormonal drugs, trace elements, physiotherapy methods and more. There are a small number of studies on the effects of biologically active drugs with neurohumoral action on the reproductive function of cows. The aim of our research was to establish the effects of biologically active substances of the neurotropic-metabolic drug "Stimulin-Cattle" on the reproductive capacity of cows. The studies were conducted on the basis of groups of analogues. The experiment selected cows after the first insemination and females who came back to sexual hunting. Experimental animals on day 7 - 9 of the sexual cycle were injected subcutaneously in the scapular region with 20 ml of the drug "Stimulin-Vet", and control according to the same scheme saline sodium chloride solution 0.9%. Cows were inseminated once by recto-cervical method. Three months later, rectal examinations of the animals were performed to determine pregnancy. The analysis of the obtained results showed that in experimental cows the fertility exceeded the control by 15.4 %. In the experimental group, 56.4 % came to sexual hunting again, and in the control group 71.8 %. Among 22 non-pregnant experimental cows, the cause of infertility in 63.6 % of animals was the anovulatory cycle, and in 36.4 % embryonic mortality. Whereas in the control of animals with anovulatory cycle was less by 42.2 %, and with embryonic mortality by the same percentage is probably higher. This situation with infertile animals suggests that the drug stimulates the development of the corpus luteum on the ovary, which promotes the secretion of more progesterone, which causes better conditions for embryo engraftment and thus reduces embryonic mortality. It was also found that animals after the first insemination react worse to the introduction of the drug than those who were inseminated for the first time, which confirms the level of fertility of 41.7 % vs. 46.7 %, respectively.

35 Vaginal pH changes due to the use of a controlled internal drug release (CIDR) and its effects on fertility of beef cows

Abstract The objective of this study was to evaluate changes in vaginal pH of beef cows enrolled in a 7-d CO-Synch+controlled internal drug release (CIDR) protocol and its effects on pregnancy. A total of 46 multiparous beef cows with no signs of vaginitis were enrolled. Individual vaginal flushes were collected from cows on D0, D7 and D10. Individual flushes were immediately analyzed for pH with a portable pH meter. As evidence of vaginitis, a CIDR score was determined at CIDR removal (D7), following a 1 to 4 scoring system: 1 = clean, no secretion; 2 = clean, clear secretion; 3 = purulent secretion; 4 = purulent secretion and blood. Pregnancy status was determined by rectal ultrasonography approximately 40 days after TAI. No cows had CIDR scores of 1 or 4, 19.6% of cows had a score of 2 and 80.4% a score of 3. Vaginal pH increased from D0 (6.88±0.007) to D7 (7.32±0.047), regardless of CIDR score (P < 0.001). Cows with a CIDR score 2 had greater pH on D7 (7.35±0.084) than on D0 (6.90± 0.14; P = 0.001), and pH on D10 was intermediate (7.14±0.14; P = 0.14). Cows with CIDR score 3 had reduced pH on D10 (7.09±0.07) when compared to D7 (7.29±0.04; P = 0.003), but greater pH on D10 than on D0 (6.87±0.07; P = 0.007). There was a pregnancy by day interaction for pH values (P = 0.046). Pregnant cows had greater vaginal pH in comparison with non-pregnant cows on D0 (6.99±0.081 and 6.68±0.09, respectively; P = 0.01) and D10 (7.26±0.08 and 6.89±0.09, respectively; P = 0.006), but not on D7 (7.34±0.05 and 7.27±0.06, respectively; P = 0.38). Non-pregnant cows had reduced vaginal pH on D10 in comparison to D7 (6.89±0.09 and 7.27±0.06, respectively; P < 0.001), whereas pregnant cows had similar vaginal pH on D10 and D7 (7.26±0.08 and 7.34±0.05, respectively; P = 0.35). We conclude that CIDR increases vaginal pH overtime and greater pH at TAI is beneficial to fertility.

PSVII-17 Program Chair Poster Pick: Reproductive function of cows depending on lipid metabolism

Abstract The aim of the study was to determine the etiopathogenesis of reproductive dysfunction in highly productive cows. Studies were conducted on cows of black-motley breed, aged 3–5 lactations, with a live weight of 480–520 kg. Cows were divided into two groups. The first group included 20 cows effective inseminated after the first insemination. The second group included 17 cows that did not fertilize after the first insemination. Blood samples (n = 253) were taken from 4–7; 14–17; 24–34; 35–50; 88–95; 195–210 days of pregnancy; during the beginning of dry period (DP); 1–4 days before calving and on the first day after calving. The content of total serum lipids in pregnant animals was 15.8% higher compared to unfertilized animals. In non-pregnant cows, a decrease in free cholesterol (by 28.65%), especially in its ether-bound fraction (14.91%), indicates a lower synthetic function of the liver, which is confirmed by the low serum levels of vitamins A and E (a difference of 11.3 and 23.65%). The DP was characterized by a significant increase in the products of lipid peroxidation - malondialdehyde by 12–17%, diene and triene conjugates - by 10–15 and 8–15%, respectively, and 1–4 days before calving in cows, which subsequently had a pathological calving, in particular - retention of placenta (5 cows), were characterized by an increased content in the blood plasma of lipid peroxidation products. Thus, the difference in the number of dienes, trienes, and malondialdehyde products was 14.0, 12.0, and 23.5%, compared with animals without obstetric pathology. On the first day after calving, this difference increased even more. Cows with retention of placenta had a significantly higher level of lipid peroxidation products and were characterized by a predominance of oxidized products over the antiradical thiol disulfide and ascorbate systems restored in the antioxidant balance.

46 Endometrial transcriptome profiles associated with bovine preimplantation pregnancy outcome and parity

Abstract Pregnancy failure in dairy cattle appears to be attributable to losses during embryogenesis, mainly within the first month. Models have estimated that pregnancies lost after day 30 of fertilization cost producers US $550/cow. The reasons for these losses are not well understood, and the transcriptome profile of the reproductive tract during the establishment of pregnancy may point to mechanisms. Thirty-eight cows in lactations 1 to 3 were artificially inseminated, and endometrial biopsies were collected on day 15 after artificial insemination to investigate the effect of parity on the preimplantation pregnancy outcome. Pregnancy status was determined by the presence of interferon-tau in the uterine flushing, revealing 19 pregnant (P) and 19 non-pregnant (NP) cows. Nineteen biopsy samples [9 cows in lactation 1 (6 P and 3 NP), 4 in lactation 2 (2 P and 2 NP), and 6 in lactation 3 (3P and 3NP)] with an average RNA integrity number of 7 were selected for RNA sequencing with an Illumina HiSeq analyzer. Sequence reads were assembled to the ARS_USD1.2.99 bovine reference genome using the CLC genomics workbench software. On average, the samples generated ~56 million reads and 94.99% were mapped to the reference genome. Differential gene expression analysis between P and NP cows identified 187, 60, and 136 differentially expressed genes (DEG) in lactation 1, 2 and 3, respectively (P < 0.01, FDR < 0.05, FC > ±2). Metabolic pathway enrichment analysis identified several DEG upregulated in lactations 2 and 3 associated with IL-17 signaling pathway, although expression of IL-17 itself was not different. This pathway is part of the protective response against extracellular bacteria and likely participates in pregnancy maintenance through local regulation of immune function. Further functional genomic analyses will be performed to determine additional metabolic pathways, key regulator genes, and functional SNPs associated with the establishment of pregnancy.

PSII-31 Effects of restricted dietary intake on protein expression of oviductal glycoprotein 1 (OVGP1) in the oviductal ampulla of beef cows

Abstract In vitro production of embryos (IVP) results in poor pregnancy rates, with 10 to 40% of embryos transferred surviving to term. Inclusion of oviductal fluid (OF) in the culture media improves success of IVP and pregnancy rates, but factors influencing OF composition are not well investigated. Therefore, we examined the effects of restricted maternal dietary intake on expression of oviductal glycoprotein 1 (OVGP1; or oviductin), a highly conserved glycoprotein involved in fertilization and early embryo cleavage. Multiparous nonpregnant beef cows were randomly assigned to one of 2 intake groups (n = 9 per group) designed to maintain [control (CON)] or lose [0.7 kg/d, negative (NEG)] body weight (BW) for 9 wk; for each cow, initial and final body condition score (BCS; 1–9 scale) and body weight (BW) were determined. Cows were estrus synchronized (Co-Synch + CIDR protocol) and slaughtered 3 d after synchronized ovulation. At slaughter, cross sections of the oviductal ampulla adjacent to the ovary containing the corpus luteum were fixed in neutral buffered formalin, embedded in paraffin, sectioned, and stained using a primary antibody against OVGP1 and fluorescently-labeled secondary antibody. Intensity of immunofluorescent staining for OVGP1 was quantified by image analysis, and differences between intake groups analyzed by t-test. Change (final – initial) in BCS and BW were greater for the NEG compared with CON cows (BCS: -1.06 vs. -0. 50, P< 0.03; and BW: -40.8 vs. -3.6 kg, P < 0.0001). The OVGP1 glycoprotein was expressed in the luminal epithelium of the ampulla, and site of expression did not differ between NEG and CON intake groups. Intensity of staining also did not differ (P >0.30) between NEG and CON intake groups (7.110 vs. 7.153 arbitrary intensity units; SEM = 0.059). Thus, restriction of maternal nutrient intake for 9 weeks did not influence protein expression of OVGP1, a major oviductal glycoprotein.

Prevalence, Etiology and Risk Factors of Endometritis in Zebus Cattle Slaughtered at the Municipal Abattoir of Ngaoundere, Adamawa Region, Cameroon

Objective: Identification of pathogens and risk factors associated with bovine endometritis is helpful in treatment and management decisions. This study was aim to determine the prevalence, etiology and risk factors of endometritis at the Ngaoundere municipal abattoir. Specifically, it was a question of characterizing slaughtered cows, evaluating the prevalence of endometritis, determining the bacterial species involved in endometritis, determining the risk factors for endometritis and the correlated effect of risk factors on the bacterial species responsible for the endometritis. Methodology: Three hundred and forty-four non-pregnant zebus cows slaughtered at the abattoir of Ngaoundere were evaluated. They were characterized and their uteri were collected, cleaned and the diameters of the cervix and uterine horns were measured using an electronic caliper. The affected uteri were sampled to determine the bacterial species responsible for the endometritis. Results: Data analysis revealed a prevalence of 12.5% for endometritis (at 95% CI). The bacteria species: Citrobacter braakii, Actinomyces pyogenes, Proteus mirabilis, Enterobacter cloacae, Escherichia coli, Aeromonas hydrophila, Bulkhoderia cepacia, Provendencia stuartii and Salmonella spp with the following proportions: 41,86%; 20,93%; 11,62%; 9,30%; 4,65%; 4,65%; 2,32%; 2,32% and 2,32%, respectively, were recorded in the positive cows. The correlation between the risk factors and the bacterial species showed that; there is a direct relation between the season and Citrobacter braakii; the rainy season and Citrobacter braakii was found to have correlation coefficients of 0.86 and 1, respectively. Nevertheless, moderate correlation values were observed between the bacteria species and the BCS (body condition score); emaciated animals and bacteria species; the Red Fulani breed and Escherichia coli with correlation coefficients of 0.42; 0.44 and 0.43, respectively. Conclusion: Endometritis is present in the bovine population ofAdamawa, and the age of the animals was a principal risk factor, with the age group (5-9 years) being the highest risk group.

Role of Brucella abortus Biovar 3 in the Outbreak of Abortion in a Dairy Cattle Herd Immunized with Brucella abortus Iriba Vaccine.

Bovine brucellosis is a widespread zoonosis caused by Brucella abortus. The disease is prevalent nationwide in Iran and is on an increasing trend among humans and livestock. The eradication of brucellosis is challenging and requires control policies at both national and regional levels. Regarding this, the aim of the current study was to evaluate if Brucella is implicated in an abortion outbreak that occurred in a dairy cattle herd, in Shahre Rey, Tehran province, Iran, after vaccination with B. abortus Iriba vaccine. The research context was a dairy cattle farm with 2,000 animals located in Shahre Rey. This farm was Brucella-free based on the results of two serological tests performed one month before vaccination. After the incidence of the first case of abortion following vaccination, serodiagnosis revealed a seropositive reaction in 30 non-pregnant cows and 19 pregnant cows that aborted later. Bacteriology and molecular typing facilitated the identification of 16 isolates of B. abortus biovar 3 from the aborted animals. None of the isolates were confirmed as B. abortus Iribavaccine strain. The results confirmed that B. abortus biovar 3 was the most prevalent biovar in the cattle of Iran. The source and time of infection in the current study were not detected most likely due to the low biosecurity level in the farm (e.g., uncontrolled introduction of the agents via humans, infected animals, semen, and vectors). In endemic countries, the serodiagnosis of brucellosis alone is not sufficient and has to be accompanied by isolation and molecular diagnosis. In addition, it is important to evaluate the presence of B. abortus in bovine semen and vectors.

Extra-renal bovine leptospirosis: Molecular characterization of the Leptospira interrogans Sejroe serogroup on the uterus of non-pregnant cows

Bovine genital leptospirosis is a chronic disease that causes reproductive disorders such as abortions, stillbirths, and estrus repetition, as well as economic losses. Despite clinical signs related to reproductive failure, the majority of studies have focused on the detection of Leptospira spp. in the urine, while few have considered the reproductive tract. Consequently, the aim of the present study was to investigate the uterus as an important extra-renal site of leptospiral infection in cows. A total of 42 non-pregnant cows were studied at a slaughterhouse. Blood samples and uterine fragments were collected for serology and molecular analysis, respectively. Concerning serologic results, 20.5 % presented as reactive, all of them against the Sejroe serogroup. Regarding lipL32 PCR, 26.2 % (11/42) of samples were positive for pathogenic Leptospira sp. Sequencing the secY gene short region enabled nine strains to be characterized, all of which were L. interrogans, with high identity (98.8 %–99.8 %) with serovar Hardjo. The use of molecular tools substantially improved the sensitivity of Leptospira sp. detection at species level and demonstrated that the uterus is an important site of bovine leptospiral infection. The findings of the present study reinforce our understanding that leptospiral uterine infection are associated to members of the Sejroe serogroup.

Effect of a high-intensity one-week training programme and student-level variables on the bovine transrectal palpation and pregnancy diagnosis skills of final-year veterinary students

BackgroundTo improve bovine transrectal palpation (TRP) and pregnancy diagnosis (PD) training, the effect of a high-intensity one-week training programme for veterinary elective students (N=59) with an interest in production animal...

Infection with Bovine Viral Diarrhea Virus in Cattle in Southern Papua, Indonesia

The aim of this preliminary study was to determine the prevalence of Bovine Viral Diarrhea Virus (BVDV) and its association with reproductive problems in cattle in Timika, Southern Papua, Indonesia, an emerging area for beef production. Serum from 77 beef cattle was collected from four villages and tested, using both antibody and antigen ELISA kits for BVDV. Data of the villages of origin, age, breed, sex and the number of parities of the cattle were collected. The pregnancy status of the cattle was determined by rectal examination. Results showed that the prevalence of BVDV antibody in individual cattle in Timika was 11.7% (CI: 6.1 – 20.0%), while at the farm level the antibody prevalence was 18.4% (CI: 8.9 – 33.7%).). Seropositivity for BVDV increased with age (P=0.02), from 0% (CI: 0 – 37.2%) in less than two-years old to 28.6% (CI: 11.3 – 55.0%) in cattle older than eight years of age. BVDV antibody was 2.9 times more prevalent in non-pregnant cows than in antibody negative cows (CI: 1.02 - 8.14, P=0.04). BVD antigen was not detected in the present study. This study reported for the first time, evidence of infection with BVDV in cattle in Papua and indicated that BVDV infection may be associated with infertility.

Short communication: The effect of ruminal administration of 5-hydroxy-l-tryptophan on circulating serotonin concentrations

The monoamine serotonin has been shown to regulate peripartal calcium homeostasis in multiparous cows and be a possible mitigation tool for hypocalcemia. Increasing circulating serotonin concentrations via prepartum intravenous (IV) administration of the serotonin precursor 5-hydroxy-L-tryptophan (5-HTP) increases postpartum calcium concentrations. However, the ability of 5-HTP to be used orally or ruminally to alter circulating serotonin concentrations has not been established. Hence, our objective was to determine if ruminal administration of 5-HTP altered circulating serotonin concentrations. Four ruminally cannulated, nonlactating, nonpregnant multiparous Holstein dairy cows were randomly assigned to 1 of 4 treatments in a 4 × 4 replicated Latin square with 4-d periods separated by a 7-d washout. On d 1 and 2 of each period, cows were dosed with 1 of 4 experimental treatments as follows: (1) 0 mg/kg of body weight (BW) of 5-HTP, (2) 1 mg/kg of BW of intraruminal 5-HTP, (3) 2 mg/kg of BW of intraruminal 5-HTP, or (4) 1 mg/kg of BW of IV 5-HTP. Infusions were administered over a 1-h period, and all groups not receiving 5-HTP IV were infused with an equal volume of IV saline to that of IV 1 mg/kg of BW of 5-HTP treatment. Continuous serial blood samples were collected beginning after d 2 of treatment administration. Whole blood serotonin concentrations were higher in cows dosed with 2 mg/kg of BW of intraruminal 5-HTP immediately after dosing when compared with cows dosed with 0 mg/kg of BW of 5-HTP on d 2, but were similar on d 3 and 4 of the experimental period. Cows receiving IV 5-HTP had the highest circulating serotonin concentrations relative to all other treatments. These findings demonstrated that 2 intraruminal dosings of 5-HTP at 2 mg/kg of BW resulted in elevated circulating serotonin concentrations relative to the control immediately after dosing. This supports the potential for 5-HTP to be used orally to manipulate circulating serotonin concentrations.

Impact of summer heat stress on the thermal environment of bovine female genital tract.

Summer heat stress (HS) is associated with a reduction in conception rate, increase in services per conception, and early embryonic death. However, the impact of summer HS on the thermal environment of different regions of the bovine female genital tract remains unknown. This study aimed to elucidate the effect of summer HS on the thermal environment of different regions of the genital tract in the cow. Three non-pregnant Japanese Black cows were investigated using a specially designed digital thermometer to record the temperatures of the rectum (RT), vagina (VT), cervix (CT), uterine body (UBT), and uterine horns (UHT) on days 0, 1, 2, 3, and 8 of the estrous cycle (day 0 = heat) in February (winter), May (spring), and August (summer). During the experiment, the temperature humidity index (THI) was recorded. THI during summer was higher (P˂0.001) than in winter and spring (78.45 ± 0.32 vs. 60.26 ± 1.20 and 68.51 ± 0.80, respectively) and was higher than the alert THI indicating HS (i.e., THI > 73). Consequently, the VT, CT, UBT, and UHT were elevated during summer HS (P < 0.05) in comparison to winter and spring. THI was positively correlated (P < 0.01) with RT, VT, CT, UBT, and UHT. Linear regression revealed that VT, CT, UBT, and UHT increased by 0.05°C per unit of THI. VT was more highly correlated than RT with THI and with the temperature of other regions of genital tract. HS induced increases in the temperatures of different regions of the female genital tract. The relationship between THI and VT could be incorporated into a mathematical model to predict the thermal load of HS on different regions of the female genital tract.

Lactating dairy cows managed for second and greater artificial insemination services with the Short-Resynch or Day 25 Resynch program had similar reproductive performance

The objective of this randomized controlled experiment was to evaluate reproductive performance and reproductive physiological outcomes of lactating Holstein cows managed for second and greater artificial insemination (AI) services with the Short-Resynch or Day 25 Resynch program. Cows from 2 commercial farms were randomly assigned after first service to the Short-Resynch (SR; n = 870) or Day 25 Resynch (D25R; n = 917) program in which they remained until 210 d after first service or left the herd. Cows in D25R received GnRH 25 ± 3 d after AI, whereas cows in SR did not. Cows not reinseminated at detected estrus (AIE) by 32 ± 3 d after AI underwent nonpregnancy diagnosis (NPD) through transrectal ultrasonography (TUS). Nonpregnant cows from both treatments with a corpus luteum (CL) ≥15 mm and an ovarian follicle ≥10 mm (hereafter, CL cows) received 2 PGF2α treatments 24 h apart, GnRH 32 h after the second PGF2α, and timed AI 16 to 18 h later. Cows that did not meet the criteria to be included in the CL group (NoCL cows) received a modified Ovsynch protocol with progesterone (P4) supplementation [P4-Ovsynch; GnRH and controlled internal drug-release device (CIDR) in, 7 d later CIDR removal and PGF2α, 24 h later PGF2α, 32 h later GnRH, and 16 to 18 h later timed AI]. In a subgroup of cows, blood samples were collected and TUS conducted at each treatment to evaluate ovarian responses to resynchronization. Binary data were analyzed with logistic regression, continuous data by ANOVA, and time-to-event data by Cox's proportional hazard regression. A greater proportion (mean; 95% CI) of cows were AIE before NPD in the SR (60.5%; 57.0-63.8; n = 3,416) than the D25R (50.1%; 46.5-53.7; n = 3,177) treatment, whereas pregnancy per AI (P/AI) at 32 d for AIE services before NPD was greater for the D25R (41.3%; 38.8-43.8; n = 1,560) than the SR (37.6%; 35.5-39.8; n = 1,961) treatment. At NPD, a greater proportion of cows in the D25R (84.3%; 82.2-86.2) than the SR (77.0%; 74.4-79.4) treatment were considered CL cows. Pregnancy per AI at 32 d was greater for the D25R than the SR treatment for all timed AI services (D25R = 43.0%; 40.2-45.9 vs. SR = 36.8%; 33.8-39.8) and for CL cows (D25R = 42.8%; 39.7-45.9 vs. SR = 33.8%; 30.6-37.2) but did not differ for NoCL cows (D25R = 39.4%; 32.1-47.3 vs. SR = 44.0%; 36.8-51.4). The hazard ratio for time to pregnancy (1.03; 0.93-1.14) and the proportion of cows not pregnant at the end of the observation period (D25R = 5.9%; 4.4-7.8 vs. SR = 6.7%; 5.0-8.7) did not differ between SR and D25R treatments. The GnRH treatment 25 d after AI resulted in more cows with P4 >1 ng/mL (D25R = 80.5%; 75.3-84.9 vs. SR = 63.6%; 57.3-69.4) and smaller follicle diameter at NPD 32 ± 3 d after AI for D25R (16.2 ± 0.4 mm) than for SR (17.5 ± 0.4 mm); however, it did not affect follicle diameter and luteal regression risk (CL cows only) before TAI. We concluded that the use of reproductive management programs including SR and D25R for CL cows and the P4-Ovsynch protocol for NoCL cows resulted in similar hazard of pregnancy and proportion of nonpregnant cows for up to 210 d after first service.

Dynamic Changes in Progesterone Concentration in Cows' Milk Determined by the At-Line Milk Analysis System Herd NavigatorTM.

Simple SummaryAccording to the literature, the at-line progesterone monitoring system Herd NavigatorTM (Lattec I/S, Hillerød, Denmark) was used in combination with a DeLaval milking robot (DeLaval Inc., Tumba, Sweden). It works automatically and provides real-time physiological information about lactating dairy cows. For making farm-management decisions, it is not only a novel tool for scientific research, but also a mechanism for improving productivity, food safety, animal well-being, the environment, and the public perception of the dairy industry. It has been hypothesized that the progesterone concentration determined by the at-line milk analysis system and changes in its dynamics correlate with the parity, reproductive status, and milk yield of cows. The aim of the current study was to evaluate relative at-line milk progesterone (mP4) dynamic changes, according to the parity and status of reproduction, and to estimate the relationship with productivity in dairy cows. Frequent automated mP4 sampling can help identify characteristics of mP4 dynamic changes associated with successful pregnancies, pregnancy losses, and potential differences in mP4 dynamics among parity groups, which have not been studied previously.The aim of the current instant study was to evaluate relative at-line milk progesterone dynamic changes according to parity and status of reproduction and to estimate the relationship with productivity in dairy cows by at-line milk analysis system Herd NavigatorTM. According to the progesterone assay, experimental animals were divided into three periods: postpartum, after insemination, and pregnancy. In the first stage of the postpartum period, progesterone levels in milk were monitored every 5 days. This period of reproductive cycle recovery was followed for 30 days (days 0–29). The second stage of the postpartum period (30–65 days) lasted until cows were inseminated. In the period (0–45 days) after cow insemination, progesterone levels were distributed according to whether or not cows became pregnant. For milk progesterone detection, the fully automated real-time progesterone analyzer Herd NavigatorTM (Lattec I/S, Hillerød, Denmark) was used in combination with a DeLaval milking robot (DeLaval Inc., Tumba, Sweden). We found that an at-line progesterone concentration is related to different parities, reproductive statuses, and milk yield of cows: the 12.88% higher concentration of progesterone in milk was evaluated in primiparous cows. The average milk yield in non-pregnant primiparous cows was 4.64% higher, and in non-pregnant multiparous cows 6.87% higher than in pregnant cows. Pregnancy success in cows can be predicted 11–15 days after insemination, when a significant increase in progesterone is observed in the group of pregnant cows.

Analysis of circulating-microRNA expression in lactating Holstein cows under summer heat stress.

Korean peninsula weather is rapidly becoming subtropical due to global warming. In summer 2018, South Korea experienced the highest temperatures since the meteorological observations recorded in 1907. Heat stress has a negative effect on Holstein cows, the most popular breed of dairy cattle in South Korea, which is susceptible to heat. To examine physiological changes in dairy cows under heat stress conditions, we analyzed the profiles circulating microRNAs isolated from whole blood samples collected under heat stress and non-heat stress conditions using small RNA sequencing. We compared the expression profiles in lactating cows under heat stress and non-heat stress conditions to understand the regulation of biological processes in heat-stressed cows. Moreover, we measured several heat stress indicators, such as rectal temperature, milk yield, and average daily gain. All these assessments showed that pregnant cows were more susceptible to heat stress than non-pregnant cows. In addition, we found the differential expression of 11 miRNAs (bta-miR-19a, bta-miR-19b, bta-miR-30a-5p, and several from the bta-miR-2284 family) in both pregnant and non-pregnant cows under heat stress conditions. In target gene prediction and gene set enrichment analysis, these miRNAs were found to be associated with the cytoskeleton, cell junction, vasculogenesis, cell proliferation, ATP synthesis, oxidative stress, and immune responses involved in heat response. These miRNAs can be used as potential biomarkers for heat stress.

Implantation associated changes in expression profile of indoleamine-2, 3-dioxygenase 1, Th1-Th2 cytokines and interferon-stimulated genes on neutrophils and peripheral blood mononuclear cells of crossbred cows

Effective bidirectional communication between the embryo and dam improves the reproductive efficiency of dairy cows. Possible role of immunosuppressive indolamine-2, 3-dioxygenase 1 (IDO1) enzyme in the regulation of maternal systemic cytokine balance/shift during early pregnancy establishment along with various interferon-stimulated genes (ISGs) expression in neutrophils and peripheral blood mononuclear cell (PBMCs) were investigated in crossbred cows. Blood was collected on days 0 i.e. day of Artificial Insemination (AI), 10, 18 and 36 post-AI followed by isolation of neutrophils and PBMCs for gene expression study of IDO1, anti-inflammatory cytokines (IL-4, IL-10 and TGFβ1), pro-inflammatory cytokines (IFNγ and TNFα) and ISGs (ISG15, MX1, MX2, OAS1) in pregnant and non-pregnant cows. Cows were grouped as pregnant and non-pregnant after pregnancy confirmation by non-return to heat, ultrasonography, per rectal examination along with progesterone and IFNτ assay. Significantly (P < 0.05) higher relative mRNA expression of IDO1 and anti-inflammatory cytokines on days 10 and 18 post-AI were observed in both neutrophils and PBMCs of pregnant cows. Pregnant cows showed significantly (P < 0.05) higher mRNA transcripts of IFNγ and TNFα genes on days 18 post-AI in both neutrophils and PBMCs. Expression of ISGs was higher (P < 0.05) on day 10th and 18th post AI in both the neutrophils and PBMCs of pregnant cows. The study indicates that systemic immune regulation by IDO1 (through cytokine shift) and ISGs in peripheral immune cells are essential for the establishment of pregnancy and may be targeted in future as biomarkers for pregnancy diagnosis.

Influence of an Exercise Program, Muscle Strength, Proprioception, and Arm Length on Veterinary Students' Bovine Pregnancy Diagnosis Accuracy.

Bovine pregnancy diagnosis (PD) by transrectal palpation (TRP) is an important skill for veterinary graduates. Factors influencing students' PD accuracy were investigated to optimize bovine PD by TRP training without increasing live animal exposure. The objective was to determine whether arm length and strength, proprioception, and exposure to a 6-week exercise training program were significantly associated with students' PD accuracy. Veterinary students (n=128) who had previously received formal theoretical and practical training in bovine TRP and PD (live cows and TRP simulators) were assessed for PD accuracy on live cows. Prior to assessment, arm muscle strength measurement, an exercise program, and additional TRP sessions on Breed'n Betsy® simulators and live cows were offered to the students. Seventy-eight students volunteered to participate in the arm length measurement, muscle strength, and proprioception testing. Of these, 35 randomly allocated students completed a 6-week exercise program, after which muscle strength was reassessed. Each student performed PDs on six cows of which the pregnancy status, ranging from 6 weeks to 9 months pregnant or not pregnant, was predetermined by an experienced veterinarian. PD accuracy was measured as sensitivity and specificity, being defined as the proportion of pregnant or nonpregnant cows, respectively, correctly identified by the student. It is concluded that hand grip strength and participation in an exercise program are significant predictors of veterinary students' PD accuracy. Implementation of an exercise program aimed at improving grip strength in the veterinary curriculum is a novel approach to improve bovine TRP and PD training.

Energy requirements for pregnant dairy cows.

This study aimed to estimate energy requirements of pregnant Holstein × Gyr cows. Different planes of nutrition were established by two feeding regimens: ad libitum or maintenance. Sixty-two nonlactating cows with average body weight of 480 ± 10.1 kg and an age of 5 ± 0.5 years were used. Cows were divided into three groups: pregnant (n = 44), non-pregnant (n = 12), and baseline reference (n = 6). The 56 pregnant and non-pregnant cows were randomly allocated into a feeding regimen: ad libitum or maintenance. To evaluate the effects of days of pregnancy, pregnant and non-pregnant animals were slaughtered at 140, 200, 240, and 270 days of pregnancy. Energy requirements for maintenance differed between pregnant and non-pregnant cows, thus two equations were developed. Net energy and metabolizable energy requirements for maintenance of non-pregnant cows were 82 kcal/kg empty body weight0.75/day and 132 kcal/kg empty body weight0.75/day, respectively. The efficiency of use of metabolizable energy for maintenance of non-pregnant cows was 62.4%. Net energy and metabolizable energy for maintenance of pregnant cows were 86 kcal/kg empty body weight0.75/day and 137 kcal/kg empty body weight0.75/day, respectively. Efficiency of use of metabolizable energy for maintenance of pregnant cows was 62.5%. The efficiency of use of metabolizable energy for gain was 41.9%. The efficiency of use of metabolizable energy for pregnancy was 14.1%. Furthermore, net energy requirement for pregnancy was different from zero from day 70 of pregnancy onwards. In conclusion, net energy and metabolizable energy requirements for maintenance of non-pregnant cows are different from pregnant cows. Furthermore, we believe that the proposed non-linear equations to estimate net energy requirements for pregnancy are more adequate than current NRC equation, and should be recommended for Holstein × Gyr cows.

To What Extent Does Photoperiod Affect Cattle Reproduction? Clinical Perspectives of Melatonin Administration – A Review

Abstract The seasonality of reproduction in most mammals is dictated by photoperiod, temperature and nutrition. Melatonin, mainly synthesized in the pineal gland, is generally accepted as the active mediator of photoperiod responses including reproduction. While non-pregnant heifers and cows show continuous sexual activity and are therefore not seasonal breeders, it has been suggested that photo-periodicity may influence the appearance of puberty in heifers and the onset of parturition. Further, the light/dark ratio may influence endocrine patterns of gestation and a shorter light period correlates with the incidence of twin pregnancies. This review considers specific aspects of the effects of photoperiod and melatonin on reproduction in dairy cattle and discusses the clinical applications of melatonin.

Characterization of the endometrial transcriptome in early diestrus influencing pregnancy status in dairy cattle after transfer of in vitro-produced embryos.

Modifications of the endometrial transcriptome at day 7 of the estrus cycle are crucial to maintain gestation after transfer of in vitro-produced (IVP) embryos, although these changes are still largely unknown. The aim of this study was to identify genes, and their related biological mechanisms, important for pregnancy establishment based on the endometrial transcriptome of recipient lactating dairy cows that become pregnant in the subsequent estrus cycle, upon transfer of IVP embryos. Endometrial biopsies were taken from Holstein Friesian cows on day 6-8 of the estrus cycle followed by embryo transfer in the following cycle. Animals were classified retrospectively as pregnant (PR, n = 8) or nonpregnant (non-PR, n = 11) cows, according to pregnancy status at 26-47 days. Extracted mRNAs from endometrial samples were sequenced with an Illumina platform to determine differentially expressed genes (DEG) between the endometrial transcriptome from PR and non-PR cows. There were 111 DEG (false discovery rate < 0.05), which were mainly related to extracellular matrix interaction, histotroph metabolic composition, prostaglandin synthesis, transforming growth factor-β signaling as well as inflammation and leukocyte activation. Comparison of these DEG with DEG identified in two public external data sets confirmed the more fertile endometrial molecular profile of PR cows. In conclusion, this study provides insights into the key early endometrial mechanisms for pregnancy establishment, after IVP embryo transfer in dairy cows.