Oestrous cycles in Bos taurus cattle

Access to an outdoor open pack promotes estrus activity in dairy cows

Dairy cows have a partial preference to access an outdoor deep-bedded pack, but the effects of continuous access to an outdoor area on estrous behaviors has not been studied. Our objective was to investigate if access to an outdoor open deep-bedded pack improves the expression of estrus behaviors. We enrolled 60 lactating Holstein cows directly after calving and followed them each for 12 weeks. Cows were housed in a single freestall pen holding 36 cows at a time, with a dynamic group composition. Half of the cows were randomly assigned to the OUTDOOR treatment; these cows had access to an outdoor open pack via an automated selection gate. INDOOR cows were housed together with OUTDOOR cows but were not allowed outdoor access. All cows were fitted with an automated activity monitor (AAM) 21 ± 3 d before expected calving date. Estrous behaviors (i.e., standing to be mounted and mounting behaviors) were continuously monitored using video, and the intensity of mounting (i.e., the number of standing to be mounted and other mounting behaviors per hour) was calculated per estrus event per cow. Temperature and humidity were monitored by data loggers indoors, and these data were used to calculate the Temperature Humidity Index (THI). Following an alert from the AAM, cows were checked to detect the presence of a dominant preovulatory follicle and an absence of a mature corpus luteum (CL) by rectal ultrasonography following milking, as well as 7 d thereafter to confirm ovulation by the presence of a new CL. A total of 94 estrus events were used in the final analysis. INDOOR cows tended to have a lower mounting intensity with increasing indoor THI, but no such effect was noted for OUTDOOR cows. The total number of cows in estrus positively influenced mounting intensity. OUTDOOR cows had a longer duration of estrus, as measured by the automated monitors, compared with INDOOR cows (12.4 ± 0.7 h versus 9.9 ± 0.8 h). Estrus event number and the total number of cows in estrus were both positively associated with estrus duration. These results indicate that access to an outdoor pack tended to increase mounting behavior for freestall housed dairy cows, especially during periods of elevated THI. We conclude that providing dairy cows access to an outdoor area can help with estrus detection and may thus help improve the reproductive programs on dairy farms.

Unveiling the role of protein kinase A (PKA) activity in bovine oviductal epithelial cells: implications on apoptotic signaling pathways during the estrous cycle

The complex interactome crucial for successful pregnancy is constituted by the intricate network of endocrine and paracrine signaling pathways, involving gametes, embryos, and the female reproductive tract. Specifically, the oviduct exhibits distinct responses to gametes and early embryos during particular phases of the estrus cycle, a process tightly regulated by reproductive hormones. Moreover, these hormones play a pivotal role in orchestrating cyclical changes within oviductal epithelial cells. To unravel the molecular mechanisms underlying these dynamic changes, our study aimed to investigate the involvement of protein kinase A (PKA) in oviductal epithelial cells throughout the estrus cycle and in advanced pregnancy, extending our studies to oviductal epithelial cell in primary culture. By a combination of 2D-gel electrophoresis, Western blotting, and mass spectrometry, we identified 17 proteins exhibiting differential phosphorylation status mediated by PKA. Among these proteins, we successfully validated the phosphorylation status of heat shock 70 kDa protein (HSP70), aconitase 2 (ACO2), and lamin B1 (LMNB1). Our findings unequivocally demonstrate the dynamic regulation of PKA throughout the estrus cycle in oviductal epithelial cells. Also, analysis by bioinformatics tools suggest its pivotal role in mediating cyclical changes possibly through modulation of apoptotic pathways. This research sheds light on the intricate molecular mechanisms underlying reproductive processes, with implications for understanding fertility and reproductive health.

Development of a biotechnology process for the production of a novel hyperglycosylated long-acting recombinant bovine follicle-stimulating hormone

Follicle-stimulating hormone (FSH) is an important protein used for bovine ovarian hyperstimulation in multiple ovulation and embryo transfer technology (MOET). Several attempts to produce bovine FSH (bFSH) in recombinant systems have been reported, nonetheless, up to date, the most commonly used products are partially purified preparations derived from porcine or ovine (pFSH or oFSH) pituitaries. Here we describe the development of a biotechnology process to produce a novel, hyperglycosylated, long-acting recombinant bFSH (LA-rbFSH) by fusing copies of a highly O-glycosylated peptide. LA-rbFSH and a nonmodified version (rbFSH) were produced in suspension CHO cell cultures and purified by IMAC with high purity levels (>99%). LA-rbFSH presented a higher glycosylation degree and sialic acid content than rbFSH. It also demonstrated a notable improvement in pharmacokinetic properties after administration to rats, including a higher concentration in plasma and a significant (seven-fold) reduction in apparent clearance (CLapp). In addition, the in vivo specific bioactivity of LA-rbFSH in rats was 2.4-fold higher compared to rbFSH. These results postulate this new molecule as an attractive substitute for commercially available porcine pituitary-derived products.

Is prolonged luteal phase a problem in lactating Holstein cows?

In this study, the main objective was to assess if long luteal phases could have other causes than pregnancy losses. We enrolled Holstein dairy cows ≥50 d in milk (DIM) from a commercial herd in Brazil from October 2016 to August 2017. All cows received an estradiol-based synchronization protocol, and, on the day of insemination (d 0), were randomly assigned either an artificial insemination (AI) or a placebo insemination (PBO) in a 3:1 ratio. An ultrasound was used to assess the presence of a CL on d17, 24, and 31, which, combined to the information from patches for the detection of estrus, was used to determine the length of the luteal phase following AI or PBO. Pregnancy was assessed by ultrasound on d 31 and cows that were pregnant were excluded from the analyses. The length of the estrous cycles was categorized as short (<17 d), normal (17-23 d), long (24-30 d), and very long (≥31 d). We compared the proportion of cows in each category between the AI and PBO groups using a cumulative ordinal mixed model. We define prolonged luteal phase as estrous cycles ≥24 d and tested its association with potential risk factors (parity, season, DIM, uterine size and position score, milk production, body condition score, and the presence of a corpus luteum (CL) at enrollment to the synchronization protocol) using mixed logistic regression models. Results are presented as odds ratio (OR) and 95% credible intervals (BCI). Data from 876 inseminations (AI: n = 616, PBO: n = 260) was collected. Overall, 12% of estrous cycles were short, 31% were normal, 19% were long, and 38% were very long. There was no difference in the odds of being in longer estrous cycle categories for the AI compared with the PBO group (OR = 0.92, 95% BCI = 0.76-1.10). Season and presence of a CL at enrollment were associated with prolonged luteal phase. In the AI group, there was a possible effect of early pregnancy losses on the lifespan of the CL, but not the PBO group, which led us to conclude that long and very long estrous cycles were not all caused by the embryonic loss. In fact, the high prevalence of cows with an extended CL lifespan in the present study suggests this could be an under- or miss-reported characteristic of high-producing lactating Holstein cows. This finding may have important repercussions in the understanding of the CL function physiology of lactating Holstein cows.

Gonadotropin-Releasing Hormone (GnRH) and Its Agonists in Bovine Reproduction I: Structure, Biosynthesis, Physiological Effects, and Its Role in Estrous Synchronization

GnRH is essential for the regulation of mammalian reproductive processes. It regulates the production and release of pituitary gonadotropins, thereby influencing steroidogenesis and gametogenesis. While primarily produced in the hypothalamus, GnRH is also produced in peripheral organs, such as the gonads and placenta. GnRH analogs, including agonists and antagonists, have been synthesized for the reproductive management of animals and humans. This review focuses on the functions of hypothalamic GnRH in the reproductive processes of cattle. In addition to inducing the surge release of LH, the pulsatile secretion of GnRH stimulates the pituitary gland to release FSH and LH, thereby regulating gonadal function. Various GnRH-based products have been synthesized to increase their potency and efficacy in regulating reproductive functions. This review article describes the chemical structures of GnRH and its agonists. This discussion extends to the gene expression of GnRH in the hypothalamus, highlighting its pivotal role in regulating the reproductive process. Furthermore, GnRH is involved in regulating ovarian follicular development and luteal phase support, and estrus synchronization is involved. A comprehensive understanding of the role of GnRH and its analogs in the modulation of reproductive processes is essential for optimizing animal reproduction.

Effect of 200 µg of gonadorelin at the first gonadotropin-releasing hormone of the Resynch-25 on ovarian dynamics and fertility in lactating Holstein cows

Our objective was to determine the effect of a 200-µg dose of GnRH 25 d after previous artificial insemination (AI) in a Resynch-25 resynchronization program on ovulatory response, circulating progesterone (P4) concentrations before and after treatment, and pregnancy per AI (P/AI) compared with a 100-µg dose in lactating Holstein cows. Experimental d 0 was considered the day of the previous AI. Lactating dairy cows (n = 3,240) with an average of 126 d in milk (DIM) and between 1 and 6 services were randomly assigned to receive 100 µg or 200 µg of GnRH on d 25 (GnRH25). On d 32 after AI, cows diagnosed nonpregnant with the presence of a corpus luteum (CL) detected by ultrasound (n = 1,249) received PGF2α treatments on d 32 and 33, followed by a GnRH 32 h later and AI 16 h after this last GnRH. Blood samples were collected on d 25, 32, and 34 to evaluate serum P4 concentrations. Transrectal ultrasonographic examination was performed on d 25 and 27 to assess ovulatory response to GnRH25. Cows were checked for pregnancy on d 32, 46, and 88 after AI. The larger dose of GnRH increased the overall proportion of cows that ovulated to the GnRH25 (25.0% for the 100-µg dose vs. 32.5% for the 200-µg dose). However, when cows were evaluated separately according to the pregnancy status on d 32 after AI, we found no treatment effect within cows pregnant and nonpregnant. Even though treatment increased the proportion of cows with serum P4 ≤0.42 ng/mL at the last GnRH treatment (G2; 86.2% for the 100-µg dose vs. 93.0% for the 200-µg dose), it did not affect P/AI on d 32, 46, and 88. Furthermore, a greater proportion of cows without a functional CL at GnRH25 had circulating P4 concentrations ≥1.00 ng/mL on d 32 and lower than 0.42 ng/mL on G2. These cows also had a greater P/AI on d 32, 46, and 88. In summary, the larger dose of GnRH on d 25 after AI did not increase the ovulatory response in nonpregnant cows and P/AI on d 32, 46, and 88 after AI after the Resynch-25 program. Additionally, nonpregnant cows without a functional CL at GnRH25 were better synchronized after the Resynch-25 protocol and had greater P/AI on d 32, 46, and 88 after timed-AI.

Transcriptomics analysis of the bovine endometrium during the perioestrus period

During the oestrous cycle, the bovine endometrium undergoes morphological and functional changes, which are regulated by alterations in the levels of oestrogen and progesterone and consequent changes in gene expression. To clarify these changes before and after oestrus, RNA-seq was used to profile the transcriptome of oestrus-synchronized beef heifers. Endometrial samples were collected from 29 animals, which were slaughtered in six groups beginning 12 h after the withdrawal of intravaginal progesterone releasing devices until seven days post-oestrus onset (luteal phase). The groups represented proestrus, early oestrus, metoestrus and early dioestrus (luteal phase). Changes in gene expression were estimated relative to gene expression at oestrus. Ingenuity Pathway Analysis (IPA) was used to identify canonical pathways and functional processes of biological importance. A total of 5,845 differentially expressed genes (DEGs) were identified. The lowest number of DEGs was observed at the 12 h post-oestrus time point, whereas the greatest number was observed at Day 7 post-oestrus onset (luteal phase). A total of 2,748 DEGs at this time point did not overlap with any other time points. Prior to oestrus, Neurological disease and Organismal injury and abnormalities appeared among the top IPA diseases and functions categories, with upregulation of genes involved in neurogenesis. Lipid metabolism was upregulated before oestrus and downregulated at 48h post-oestrus, at which point an upregulation of immune-related pathways was observed. In contrast, in the luteal phase the Lipid metabolism and Small molecule biochemistry pathways were upregulated.

Uterine Fluid Extracellular Vesicles Proteome Is Altered During the Estrous Cycle

Uterine environment is tightly and finely regulated via various signaling pathways mediated through endocrine, exocrine, autocrine, juxtacrine, and paracrine mechanisms. In utero signaling processes are paramount for normal and abnormal physiology which involves cell to cell, cells to gametes, cells to embryo, and even interkingdom communications due to presence of uterine microbiota. Extracellular vesicles (EVs) in the uterine fluid (UF) and their cargo components are known to be mediators of in utero signaling and communications. Interestingly, the changes in UF-EV proteome during the bovine estrous cycle and the effects of these differentially enriched proteins on embryo development are yet to be fully discovered. In this study, shotgun quantitative proteomics-based mass spectrometry was employed to compare UF-EV proteomes at day 0, 7, and 16 of the estrous cycle to understand the estrous cycle-dependent dynamics. Furthermore, different phase UF-EVs were supplemented in embryo cultures to evaluate their impact on embryo development. One hundred fifty-nine UF-EV proteins were differentially enriched at different time points indicating the UF-EV proteome is cycle-dependent. Overall, many identified pathways are important for normal uterine functions, early embryo development, and its nutritional needs, such as antioxidant activity, cell morphology and cycle, cellular homeostasis, cell adhesion, and carbohydrate metabolic process. Furthermore, the luteal phase UF-EVs supplementation increased in vitro blastocyst rates from 25.0 ± 5.9% to 41.0 ± 4.0% (p ≤ 0.05). Our findings highlight the importance of bovine UF-EV in uterine communications throughout the estrous cycle. Interestingly, comparison of hormone-synchronized EV proteomes to natural cycle UF-EVs indicated shift of signaling. Finally, UF-EVs can be used to improve embryo production in vitro.

The immunolocalization of cadherins and beta-catenin in the cervix and vagina of cycling cows

The adherens junctions (AJs) maintain the epithelial cell layers' structural integrity and barrier function. AJs also play a vital role in various biological and pathological processes. AJs perform these functions through the cadherin-catenin adhesion complex. This study investigated the presence, cell-specific localization, and temporal distribution of AJ components such as classical type I cadherins and beta-catenin in the cow cervix and vagina during the estrous cycle. Immunohistochemistry and Western blot analysis results demonstrated that beta-catenin and epithelial (E)-, neural (N)-, and placental (P)-cadherins are expressed in the cow cervix and vagina during the estrous cycle. These adhesion molecules were localized in the membrane and cytoplasm of the ciliated and non-ciliated cervical cells and the stratified vaginal epithelial cells. Positive immunostaining for P-, N-cadherin, and beta-catenin was also observed in the vascular endothelial cells of the cervical and vaginal stroma. Quantitative immunohistochemistry examinations revealed that in the cervical and vaginal epithelia, P-cadherin's optical density values (ODv) were the highest; in contrast, the N-cadherin ODv were the lowest. The ODv of P-cadherin and beta-catenin in the cervical epithelium and E-cadherin in the vagina were significantly higher in the luteal phase versus the follicular phase of the estrous cycle. Furthermore, the ODv of P-cadherin, N-cadherin, and beta-catenin in the cervix's central and peripheral epithelial regions were different during the estrous cycle. These findings indicate that classical cadherins and beta-catenin in the cervix and vagina exhibit cell- and tissue-specific expression patterns under the influence of estrogen and progesterone hormones during the estrous cycle.

Animal- and herd-level factors associated with onset of puberty in grazing dairy heifers

AIMS

To explore animal- and herd-level risk factors influencing age at puberty in predominantly Holstein-Friesian dairy heifers managed in seasonal, pasture-based systems.

METHODS

Heifers born in spring 2018 (n = 5,010) from 54 commercial dairy herds in New Zealand were visited on three occasions when the mean heifer age, within herd, was 10 (visit 1; V1), 11 (V2) and 12 (V3) months old. Blood samples were collected on each visit and liveweight, stature and anogenital distance (AGD) were measured at V2. Heifers were defined as having reached puberty at the first visit where blood progesterone was elevated (≥ 1 ng/mL). Animal-level response variables included pubertal status by V1, V2 and V3, and age at puberty (or age at V3 plus 31 days for those that had not attained puberty by V3). To explore herd-level management factors, farmers answered a questionnaire relating to animal location, land type, health, feeding, and management between weaning and mating. A partial least squares regression was undertaken to identify herd-level factors associated with the greatest influence on puberty rate within herd.

RESULTS

The mean age at puberty was 352 (SD 34.9) days. Heavier animals at a greater proportion of expected mature liveweight based on their breeding value for liveweight, or animals with a higher breed proportion of Jersey and lower breed proportion of Holstein, were associated with earlier puberty. Herd puberty rates varied widely among enrolled herds, and averaged 20%, 39% and 56% by V1, V2 and V3, respectively. Liveweight, followed by breed and land type, had the greatest influence on the herd puberty rate. Heifer herds with a greater mean liveweight (absolute and proportion of expected mature weight) or greater Jersey proportion had more animals that reached puberty at any visit, whereas herds located on steep land or with greater Holstein breed proportions had lower puberty rates. Management-related factors such as vaccinations, provision of feed supplements, and weighing frequency were also herd-level risk factors of puberty but had less influence.

CONCLUSIONS AND CLINICAL RELEVANCE

This study highlights the importance of having well-grown heifers for increasing the chances of earlier puberty onset and the effect of breed and youngstock management to achieve growth targets. These outcomes have important implications for the optimal management of heifers to achieve puberty before their maiden breeding and for the timing of measurements to potentially incorporate a puberty trait in genetic evaluations.

Scientific characterization methods for better utilization of cattle dung and urine: a concise review

Cattle are usually raised for food, manure, leather, therapeutic, and draught purposes. Biowastes from cattle, such as dung and urine, harbor a diverse group of crucial compounds, metabolites/chemicals, and microorganisms that may benefit humans for agriculture, nutrition, therapeutics, industrial, and other utility products. Several bioactive compounds have been identified in cattle dung and urine, which possess unique properties and may vary based on agro-climatic zones and feeding practices. Therefore, cattle dung and urine have great significance, and a balanced nutritional diet may be a key to improved quality of these products/by-products. This review primarily focuses on the scientific aspects of biochemical and microbial characterization of cattle biowastes. Various methods including genomics for analyzing cattle dung and gas chromatography-mass spectroscopy for cattle urine have been reviewed. The presented information might open doors for the further characterization of cattle resources for heterogeneous applications in the production of utility items and addressing research gaps. Methods for cattle's dung and urine characterization.

Peri-estrus activity and mounting behavior and its application to estrus detection in Hanwoo (Korea Native Cattle)

This study was conducted to investigate the change in activity and mounting behavior in Hanwoo (Korean Native Cattle) during the peri-estrus period and its application to estrus detection. A total of 20 Hanwoo cows were fitted with a neck-collar accelerometer device, which measured the location and acceleration of cow movements and recorded the number of instances of mounting behavior by the altitude data. The data were analyzed in three periods (24-, 6-, and 2-h periods). Blood samples were collected for 5 days after the prostaglandin F2α (PGF2α) injection, and the concentrations of estradiol, progesterone, follicle-stimulating hormone, and luteinizing hormone were determined by enzyme-linked immunosorbent assays. Activity and mounting behavior recorded over 2-h periods significantly increased as estrus approached and were more efficient at detecting estrus than over 24- and 6-h periods (p < 0.05). Endocrine patterns did not differ with the variation of individual cows during the peri-estrus period (p > 0.05). Activity was selected as the best predictor through stepwise discriminant analysis. However, activity alone is not enough to detect estrus. We suggest that a combination of activity and mounting behavior may improve estrus detection efficiency in Hanwoo. Further research is necessary to validate the findings on a larger sample size.

Use of intravaginal lactic acid bacteria prepartum as an approach for preventing uterine disease and its association with fertility of lactating dairy cows

The objective of this study was to evaluate the effects of the use of intravaginal probiotics prepartum on the incidence risk of metritis postpartum and conception risk after first artificial insemination (AI). A total of 606 Holstein cows were enrolled 3 wk before their expected calving date from 2 farms. Cows were randomly assigned to either receive a 2-mL dose of a combination of 3 lactic acid bacteria (probiotic treatment) washed with approximately 2 mL of a sterile saline solution, into the vaginal canal twice weekly until parturition, or no intervention (control). Metritis diagnoses were carried out on 6 and 12 d postpartum. Vaginal discharge and rectal temperature were assessed, and vaginal discharge was scored on a scale from 1 to 4, where 1 = clear and 4 = fetid, purulent discharge. Metritis was defined as cows having a vaginal discharge score of 4 with or without fever (rectal temperature ≥39.5°C) on either 6 or 12 d postpartum, or both. Cows were bred after a 60-d voluntary waiting period primarily via the detection of estrus using automated activity monitors; cows not found in estrus were enrolled onto timed AI protocols to receive first breeding before 100 DIM. Pregnancy diagnosis was carried out at d 35 ± 7 post-AI on both farms. Data were analyzed via ANOVA using linear mixed regression models and survival analysis using a Cox proportional hazard model. Total incidence risk of metritis was 23.7% and 34.4% on farm A and farm B, respectively. Overall, the incidence of metritis was not different between treatment groups (control: 41.6 ± 3.8%; probiotic: 38.6 ± 4.0%); however, an interaction by farm was detected, where the probiotic treatment reduced metritis on one farm but not on the other. Conception risk after first AI was not affected by treatment. However, we detected an interaction between parity and treatment, where multiparous cows receiving the probiotic treatment were more likely to become pregnant compared with multiparous cows within the control group (hazard ratio: 1.33; 95% confidence interval: 1.10-1.60); no effect of probiotic treatment was found on the hazard of pregnancy for primiparous cows. In addition, the probiotic treatment was associated with an increased proportion of cows being detected in estrus for the first AI postpartum. In conclusion, vaginal probiotic treatment applied during the 3 wk prepartum was associated with a decreased incidence of metritis on one farm but not the other, suggesting that farm management may be a key player influencing treatment efficacy. Overall, probiotic treatment was found to have only limited effects on fertility in the current study.

Review: Endometrial function in pregnancy establishment in cattle

The endometrium is fundamentally required for successful pregnancy in ruminants and species where the posthatching conceptus undergoes a protracted elongation and peri-implantation phase of pregnancy. Moreover, there are substantial waves of pregnancy loss during this pre- and peri-implantation period of pregnancy the precise source of which has not been clearly defined i.e., the maternal uterine contribution to this loss. Understanding the molecular interactions required for successful pregnancy in cattle will allow us to intervene to support pregnancy success during this vulnerable window. The endometrium contributes to most key developmental milestones of pregnancy establishment, including (1) contributing to the regulation of the oestrus cycle, (2) nourishing the preimplantation conceptus, (3) responding to the conceptus to create a more receptive microenvironment, (4) providing essential biophysical support, and (5) signalling and producing factors which affect the mother systemically. This review will summarise what we currently know about conceptus-maternal interactions as well as identify the gaps in our knowledge that could be filled with newer in vitro model approaches. These include the use of microfluidics, organ-on-a-chip devices, and bioinformatic approaches. This will help maximise food production efficiency (both meat and dairy) and decrease the environmental burden, while enhancing our understanding of the fundamental processes required for successful implantation in cattle.

Cow characteristics associated with the variation in number of contacts between dairy cows

In modern freestall barns where large groups of cows are housed together, the behavior displayed by herd mates can influence the welfare and production of other individuals. Therefore, understanding social interactions in groups of dairy cows is important to enhance herd management and optimize the outcomes of both animal health and welfare in the future. Many factors can affect the number of social contacts in a group. This study aimed to identify which characteristics of a cow are associated with the number of contacts it has with other group members in 2 different functional areas (feeding and resting area) to increase our understanding of the social behavior of dairy cows. Inside 2 herds housed in freestall barns with around 200 lactating cows each, cow positions were recorded with an ultra-wideband real-time location system collecting all cows' positions every second over 2 wk. Using the positioning data of the cows, we quantified the number of contacts between them, assuming that cows spending time in proximity to one another (within a distance of 2.5 m for at least 10 min per day) were interacting socially. We documented in which barn areas these interactions occurred and used linear mixed models to investigate if lactation stage, parity, breed, pregnancy status, estrus, udder health, and claw health affect the number of contacts. We found variation in the number of contacts a cow had between individuals in both functional areas. Cows in later lactation had more contacts in the feeding area than cows in early lactation. Furthermore, in one herd, higher parity cows had fewer contacts in the feeding area than first parity cows, and in the other herd, cows in third parity or higher had more contacts in the resting area. This study indicates that cow characteristics such as parity and days in milk are associated with the number of contacts a cow has daily to its herd mates and provides useful information for further research on social interactions of dairy cows.

Progress toward species-tailored prematuration approaches in carnivores

In the past four decades, the bovine model has been highly informative and inspiring to assisted reproductive technologies (ART) in other species. Most of the recent advances in ART have come from studies in cattle, particularly those unveiling the importance of several processes that must be recapitulated in vitro to ensure the proper development of the oocyte. The maintenance of structural and functional communications between the cumulus cells and the oocyte and a well-orchestrated chromatin remodeling with the gradual silencing of transcriptional activity represent essential processes for the progressive acquisition of oocyte developmental competence. These markers are now considered the milestones of physiological approaches to increase the efficiency of reproductive technologies. Different in vitro approaches have been proposed. In particular, the so-called "pre-IVM" or "prematuration" is a culture step performed before in vitro maturation (IVM) to support the completion of the oocyte differentiation process. Although these attempts only partially improved the embryo quality and yield, they currently represent a proof of principle that oocytes retrieved from an ovary or an ovarian batch shouldn't be treated as a whole and that tailored approaches can be developed for culturing competent oocytes in several species, including humans. An advancement in ART's efficiency would be desirable in carnivores, where the success is still limited. Since the progress in reproductive medicine has often come from comparative studies, this review highlights aspects that have been critical in other species and how they may be extended to carnivores.

Characterization of bovine uterine fluid extracellular vesicles proteomic profiles at follicular and luteal phases of the oestrous cycle

Extracellular vesicles (EV) have been identified in uterine fluid (UF), however the bovine UF-EV profile during different phases of the oestrous cycle has not yet been established. Therefore, we compared the UF-EV, and their protein profile at follicular and luteal phases of the oestrous cycle. UF samples were collected from healthy uteri of six live and six slaughtered cows at follicular or luteal phases. Isolation of EV was performed using tangential flow filtration followed by size exclusion chromatography. EV were characterized by nanoparticle tracking analysis (NTA), fluorescence NTA, zeta potential, and transmission electron microscopy. Mass-spectrometry was used to evaluate EV protein profile from live cows. Particle concentrations (mean ± SD) were higher (P < 0.05) at follicular than at luteal phase in both live (1.01 × 108 ± 1.66 × 107 vs 7.56 × 107 ± 1.80 × 107, respectively) and slaughtered cows (1.17 × 108 ± 2.34 × 107 vs 9.12 × 107 ± 9.77 × 106, respectively). The proportion of fluorescently labelled EV varied significantly between follicular and luteal phases across live (28.9 ± 1.9% vs 19.3 ± 2.8%, respectively) and slaughtered cows (26.5 ± 6.3% vs 27.3 ± 2 .7%, respectively). In total, 41 EV proteins were differentially expressed between the phases. Some of the proteins were involved in reproductive processes, cell adhesion and proliferation, and cellular metabolic processes. The results indicated differences in bovine UF-EV concentration and protein profile at follicular and luteal phases, which would suggest that EV modulate uterine microenvironment across the oestrous cycle. Further research is needed to understand the effect of EV changes throughout the oestrous cycle.

Noninvasive monitoring of steroid hormone production and activity of zoo-housed banteng (Bos javanicus)

This study describes patterns of steroid hormone production and activity for banteng (Bos javanicus), an endangered member of the Bovidae family. Using validated assays, concentrations of fecal progestagens, androgens, and glucocorticoids were quantified for four females and one male at the Saint Louis Zoo. A commercial activity monitor was also validated for assessing movement. The devices were then used to characterize activity in relation to season, reproductive status, and fecal steroid concentrations. General linear mixed models assessed differences in activity and steroid concentrations among individuals, in regards to reproductive status and season. Ovulatory cycle patterns, changes in activity around estrus and parturition, and events correlated with increased glucocorticoid production were also documented. Cycle lengths were 24.7 ± 0.4 days, and cycle lengths varied among individuals. Females cycled year-round, but luteal progestagen concentrations, along with glucocorticoids and male androgens, increased during the summer. Activity also increased in the summer. Progestagen concentrations were greater in pregnant females, and the gestation length of one pregnancy was 254 days. Pregnant females were less active overall, but activity increased the day before parturition. Activity was also greater preceding the onset of the luteal phase. The majority of glucocorticoid concentrations were in the range of baseline concentrations. However, a small number of elevated concentrations were correlated with husbandry and veterinary events. This study is the first to validate non-invasive methods for monitoring reproduction, welfare, and activity of banteng. Our results may contribute to the improved management of captive populations.

Integration of transcriptomic and metabolomic analysis of the mechanism of dietary N-carbamoylglutamate in promoting follicle development in yaks

Yak is the main livestock in the highlands of China. The low reproductive rate of yaks is a serious constraint on their production and utility. N-carbamylglutamate (NCG) can increase arginine synthesis in mammals and has been shown to improve reproductive performance. Twelve multiparous and simutaneous anoestrous female yaks were randomly divided into two groups, one of which was fed the basal diet (Control, n = 6), and the other was fed the basal diet supplemented with NCG at 6 g/day/yak (NCG, n = 6). All yaks were slaughtered on the 32nd day (the time predicted for the selection of the last wave of dominant follicles), and their ovarian tissues were collected and follicles were classified. NCG supplementation increased the number of large ovarian follicles (diameter > 10 mm), as well as caused significant changes in the transcriptional and metabolic levels in yak ovaries which due to the differential expression of 889 genes and 94 metabolites. Integrated analysis of the transcriptomics and metabolomics data revealed that the differentially expressed genes and differential metabolites were primarily involved in the process of energy metabolism, amino acid metabolic pathways, carbohydrate metabolic pathways, and lipid metabolic pathways. The highlighted changes were associated with amino acid synthesis and metabolism, ovarian steroid hormone synthesis, the pentose phosphate pathway, and the tricarboxylic acid cycle, suggesting that NCG supplementation may promote estrogen synthesis and help regulate follicular development by altering the pathways associated with glucose catabolism. The results present important clues for understanding the mechanisms by which NCG supplementation promotes follicular development in yaks. The findings of this study provide a basis for the development and application of NCG in optimizing animal reproduction, including yak reproductive performance, which may help optimize livestock management and uplift the pastoral economy.

RNA-Sequencing based analysis of bovine endometrium during the maternal recognition of pregnancy

BACKGROUND

Maternal recognition is the crucial step for establishing pregnancy in cattle. This study aims to identify endometrial genes and biological pathways involved in the maternal recognition of pregnancy. Caruncular endometrial tissues were collected from Day 15-17 of gestation (pregnant), non-pregnant (absence of conceptus), and cyclic (non-bred) heifers.

RESULTS

Total RNAs were isolated from the caruncular endometrial tissues of pregnant, non-pregnant, and cyclic heifers, and were subjected to high-throughput RNA-sequencing. The genes with at least two-fold change and Benjamini and Hochberg p-value ≤ 0.05 were considered differentially expressed genes and further confirmed with quantitative real-time PCR. A total of 107 genes (pregnant vs cyclic) and 98 genes (pregnant vs non-pregnant) were differentially expressed in the pregnant endometrium. The most highly up-regulated genes in the pregnant endometrium were MRS2, CST6, FOS, VLDLR, ISG15, IFI6, MX2, C15H11ORF34, EIF3M, PRSS22, MS4A8, and TINAGL1. Interferon signaling, immune response, nutrient transporter, synthesis, and secretion of proteins are crucial pathways during the maternal recognition of pregnancy.

CONCLUSIONS

The study demonstrated that the presence of conceptus at Day 15-17 of gestation affects the endometrial gene expression related to endometrial remodeling, immune response, nutrients and ion transporters, and relevant signaling pathways in the caruncular region of bovine endometrium during the maternal recognition of pregnancy.

Stimulatory effects of TGFα in granulosa cells of bovine small antral follicles

Intraovarian growth factors play a vital role in influencing the fate of ovarian follicles. They affect proliferation and apoptosis of granulosa cells (GC) and can influence whether small antral follicles continue their growth or undergo atresia. Transforming growth factor-alpha (TGFα), an oocyte-derived growth factor, is thought to regulate granulosa cell function; yet its investigation has been largely overshadowed by emerging interest in TGF-beta superfamily members, such as bone morphogenetic proteins (BMP) and anti-Mullerian hormone (AMH). Here, effects of TGFα on bovine GC proliferation, intracellular signaling, and cytokine-induced apoptosis were evaluated. Briefly, all small antral follicles (3-5 mm) from slaughterhouse specimens of bovine ovary pairs were aspirated and the cells were plated in T25 flasks containing DMEM/F12 medium, 10% FBS, and antibiotic-antimycotic, and incubated at 37 °C in 5% CO2 for 3 to 4 d. Once confluent, the cells were sub-cultured for experiments (in 96-, 12-, or 6-well plates) in serum-free conditions (DMEM/F12 medium with ITS). Exposure of the bGC to TGFα (10 or 100 ng/mL) for 24 h stimulated cell proliferation compared to control (P < 0.05; n = 7 ovary pairs). Proliferation was accompanied by a concomitant increase in mitogen-activated protein kinase (MAPK) signaling within 2 h of treatment, as evidenced by phosphorylated ERK1/2 expression (P < 0.05, n = 3 ovary pairs). These effects were entirely negated, however, by the MAPK inhibitor, U0126 (10uM, P < 0.05). Additionally, prior exposure of the bGC to TGFα (100 ng/mL) failed to prevent Fas Ligand (100 ng/mL)-induced apoptosis, as measured by caspase 3/7 activity (P < 0.05, n = 7 ovary pairs). Collectively, the results indicate TGFα stimulates proliferation of bGC from small antral follicles via a MAPK/ERK-mediated mechanism, but this action alone fails to prevent apoptosis, suggesting that TGFα may be incapable of promoting their persistence in follicles during the process of follicular selection/dominance.

Mammalian cumulus-oocyte complex communication: a dialog through long and short distance messaging

Communications are crucial to ovarian follicle development and to ovulation, and while both folliculogenesis and oogenesis are distinct processes, they share highly interdependent signaling pathways. Signals from distant organs such as the brain must be processed and compartments within the follicle have to be synchronized. The hypothalamic–pituitary–gonadal (HPG) axis relies on long-distance signalling analogous to wireless communication by which data is disseminated in the environment and cells equipped with the appropriate receptors receive and interpret the messages. In contrast, direct cell-to-cell transfer of molecules is a very targeted, short distance messaging system. Numerous signalling pathways have been identified and proven to be essential for the production of a developmentally competent egg. The development of the cumulus-oocyte complex relies largely on short distance communications or direct transfer type via extensions of corona radiata cells through the zona pellucida. The type of information transmitted through these transzonal projections is still largely uncharacterized. This review provides an overview of current understanding of the mechanisms by which the gamete receives and transmits information within the follicle. Moreover, it highlights the fact that in addition to the well-known systemic long-distance based communications from the HPG axis, these mechanisms acting more locally should also be considered as important targets for controlling/optimizing oocyte quality.

Effect of Negative Energy Balance on Plasma Metabolites, Minerals, Hormones, Cytokines and Ovarian Follicular Growth Rate in Holstein Dairy Cows

Introduction

The aim of this study was to evaluate the effect of negative energy balance (NEB) on the final growth of the dominant ovarian follicle in Holstein cows.

Material and Methods

Cows at 14 to 21 d postpartum from an intensive dairy farm were randomly selected and allocated into a positive energy balance group (PEB, with β-hydroxybutyric acid (BHBA) level < 1.2 mmol/L, n = 15) and an NEB group (BHBA > 1.2 mmol/L, n = 15). Plasma samples were collected at 21, 50 and 55 d postpartum to assess the concentrations of energy metabolites, minerals, hormones and cytokines. Ovaries were examined by transrectal ultrasound on days 50 and 55 (120 hours later) to evaluate the diameter of the largest follicle.

Results

Compared with PEB cows, there were a more severe body condition loss and a lower milk yield in NEB cows (P < 0.05) and these had greater concentrations of plasma BHBA, non-esterified fatty acids, triglycerides, urea nitrogen, growth hormone, interleukin 6, and fibroblast growth factor 21 and lesser concentrations of plasma glucose, total cholesterol, insulin, insulin-like growth factor 1, insulin-like growth factor binding protein 3, leptin, brain-derived neurotrophic factor and angiopoietin-like protein 8 on d 21 (P < 0.05), while plasma minerals were not affected by energy status (P > 0.05). These changes persisted until the end of the study period (50–55 days postpartum) resulting in a lower follicular growth rate for cows in the NEB than the PEB group.

Conclusion

These observations indicate that follicular growth rate is associated with measurable changes in energy metabolite, hormone and cytokine concentrations caused by early postpartum NEB.

Modelling Oscillatory Patterns in the Bovine Estrous Cycle with Boolean Delay Equations

Boolean delay equations (BDEs), with their relatively simple and intuitive mode of modelling, have been used in many research areas including, for example, climate dynamics and earthquake propagation. Their application to biological systems has been scarce and limited to the molecular level. Here, we derive and present two BDE models. One is directly derived from a previously published ordinary differential equation (ODE) model for the bovine estrous cycle, whereas the second model includes a modification of a particular biological mechanism. We not only compare the simulation results from the BDE models with the trajectories of the ODE model, but also validate the BDE models with two additional numerical experiments. One experiment induces a switch in the oscillatory pattern upon changes in the model parameters, and the other simulates the administration of a hormone that is known to shift the estrous cycle in time. The models presented here are the first BDE models for hormonal oscillators, and the first BDE models for drug administration. Even though automatic parameter estimation still remains challenging, our results support the role of BDEs as a framework for the systematic modelling of complex biological oscillators.

Estimation of the true prevalence of inaccurate artificial inseminations in Irish milk recording dairy cows using a Bayesian latent class analysis

Inaccurate artificial insemination (IAI) refers to an artificial insemination (AI) that is performed when a cow is not in oestrus. IAIs have economic impacts on the dairy industry through of semen wastage or iatrogenic pregnancy loss. However, few studies have quantified the prevalence of IAIs in a population. The primary objective of this prospective study was to estimate the cow-level true prevalence of IAIs in Irish milk recording dairy herds using a latent class model with a Bayesian framework. Milk samples were collected at a milk recording laboratory from 576 dairy cows in 125 herds who had received an AI on the same day they were sampled for routine milk constituent analysis. Milk progesterone (MP4) analysis was conducted on these samples using radioimmunoassay to determine the progesterone concentration. Fertility data (i.e., subsequent calving date) was retrospectively obtained from the Irish National Cattle Breeding Federation for milk sampled cows and an apparent conception (AC) to the sample AI was determined based on an estimated gestational range of 270-290 days. Both tests (MP4 and AC) were used in a latent class model to estimate the true prevalence of IAI. For the MP4 test, a concentration of ≥ 5 ng/mL in whole milk was deemed to be test positive while for the AC test, a cow that did not conceive to the sampled AI was deemed test positive. Prior information for prevalence of IAI was obtained from a literature review while MP4 sensitivity (Se) and specificity (Sp) were obtained from expert opinion. Non-informative priors were used for the Se and Sp of the AC test. Posterior inferences (median and 95 % Bayesian probability intervals; BPI) were obtained using the 'rjags' package in the R statistical software. In the final model, median cow-level true prevalence of IAI was 4.4 % (BPI; 1.7-9.0 %). Median Se and Sp estimates for MP4, were 83.0 % (BPI; 65.0-96.2 %) and were 97.4 % (BPI; 94.6-99.6 %), respectively. Median Se and Sp estimates for AC, were 64.8 % (BPI; 44.5-88.6 %) and 49.8 % (BPI; 45.3-54.1 %), respectively. The present study estimates that the overall cow-level true prevalence of IAI in Irish dairy cows is relatively low. This is the first study to report the cow-level true prevalence of IAI using a Bayesian latent class model.

The ovarian follicle of ruminants: the path from conceptus to adult

This review resulted from an international workshop and presents a consensus view of critical advances over the past decade in our understanding of follicle function in ruminants. The major concepts covered include: (1) the value of major genes; (2) the dynamics of fetal ovarian development and its sensitivity to nutritional and environmental influences; (3) the concept of an ovarian follicle reserve, aligned with the rise of anti-Müllerian hormone as a controller of ovarian processes; (4) renewed recognition of the diverse and important roles of theca cells; (5) the importance of follicular fluid as a microenvironment that determines oocyte quality; (6) the 'adipokinome' as a key concept linking metabolic inputs with follicle development; and (7) the contribution of follicle development to the success of conception. These concepts are important because, in sheep and cattle, ovulation rate is tightly regulated and, as the primary determinant of litter size, it is a major component of reproductive efficiency and therefore productivity. Nowadays, reproductive efficiency is also a target for improving the 'methane efficiency' of livestock enterprises, increasing the need to understand the processes of ovarian development and folliculogenesis, while avoiding detrimental trade-offs as greater performance is sought.

Cross-sectional analyses of a national database to determine if superior genetic merit translates to superior dairy cow performance

Various studies have validated that genetic divergence in dairy cattle translates to phenotypic differences; nonetheless, many studies that consider the breeding goal, or associated traits, have generally been small scale, often undertaken in controlled environments, and they lack consideration for the entire suite of traits included in the breeding goal. Therefore, the objective of the present study was to fill this void, and in doing so, provide producers with confidence that the estimated breeding values (EBV) included in the breeding goal do (or otherwise) translate to desired changes in performance among commercial cattle; an additional outcome of such an approach is the identification of potential areas for improvements. Performance data on 536,923 Irish dairy cows (and their progeny) from 13,399 commercial spring-calving herds were used. Association analyses between the cow's EBV of each trait included in the Irish total merit index for dairy cows (which was derived before her own performance data accumulated) and her subsequent performance were undertaken using linear mixed models; milk production, fertility, calving, maintenance (i.e., liveweight), beef, health, and management traits were all considered in the analyses. Results confirm that excelling in EBV for individual traits, as well as on the total merit index, generally delivers superior phenotypic performance; examples of the improved performance for genetically elite animals include a greater yield and concentration of both milk fat and milk protein, despite a lower milk volume, superior reproductive performance, better survival, improved udder and hoof health, lighter cows, and fewer calving complications; all these gains were achieved with minimal to no effect on the beef merit of the dairy cow's progeny. The associated phenotypic change in each performance trait per unit change in its respective EBV was largely in line with the direction and magnitude of expectation, the exception being for calving interval. Per unit change in calving interval EBV, the direction of phenotypic response was as anticipated but the magnitude of the response was only half of what was expected. Despite the deviation from expectation between the calving interval EBV and its associated phenotype, a superior total merit index or a superior fertility EBV was indeed associated with an improvement in all detailed fertility performance phenotypes investigated. Results substantiate that breeding is a sustainable strategy of improving phenotypic performance in commercial dairy cattle and, by extension, profit.

Evaluation of a small volume oil-free in vitro production system for bovine embryos

Background:

Embryos are usually produced in culture systems with an oil overlay, which conveys protection against the evaporation of water and microbial contamination. The oil can also release toxic substances and absorb essential components, such as hormones, which adversely affect the quality of the oocytes and the development of embryos in vitro.

Objective:

The aim of this study was to validate an oil‐free bovine in vitro production (IVP) system.

Method:

Cumulus–oocyte complexes collected from abattoir‐derived ovaries were matured, fertilized and cultured employing a standard system. The quantity of medium in both groups (with and without an oil overlay) and throughout all stages of IVP was maintained at a volume of 100 μl. The oil group was covered with paraffin oil. The maturation stage of oocytes was assessed using fluorescence staining after 24 hr and developmental stages of embryos were evaluated on day 8. The expanded day 8 blastocysts were assessed by live–dead staining.

Results:

Oocytes matured in the absence of an oil overlay had significantly higher maturation rates when compared against matured oocytes in medium with an oil overlay. Steroid concentration is higher in medium after maturation without oil cover. The developmental rate was significantly higher after culture without oil overlay. The total cell number and the live–dead ratio was not significantly different. The osmolality did not differ between both groups during maturation and slightly decreased during culture without oil.

Conclusion:

Based on the current study, bovine oil‐free IVP systems can be suggested as an alternative to oil‐covered medium.

Effect of variable interservice interval on conception in crossbred cows

Reducing number of services per conception holds the key for profitable dairying. The widely considered estrous cycle length of 21 d has been refuted, a change that can seriously implicate fertility. The present investigation evaluated association amongst interservice interval (ISI, the period intervening two successive inseminations) and services per conception alongwith certain cow related variables (age, lactation number, days in milk to AI, days in milk at conception, age at conception and 305 d lactation yield). Data on 768 ISIs (range: 17 to 24 d) from 1,479 AIs (600 in normal; 879 in repeat breeders) in 193 lactating Jersey crossbred cows conceiving to different number of inseminations, was utilized. The ISI data in form of average, immediately prior to conception and pattern (regular – if ISI between AIs was of same duration; irregular – if ISI between AIs was of different durations) was considered for analysis. Nearly 84% of ISI ranged from 19 to 22 d, merely 22.6% being of 21 d (overall average of 20.3±0.44 d). Correlation matrix revealed a solitary, significant and negative relation of ISI, both average and prior to conception, with services per conception. The ISI of ≥21 d culminated consistently into more number of pregnant cows as well as lesser services per conception. The forward selection regression model predicted reduction in ISI by 0.17 d with each additional insemination. Irregular pattern of ISI was also unfavourable for conception. The probable mechanisms for variable ISI in light of conception have been exhaustively elaborated, which could pave potential future studies aiming reduced reproductive wastage.

Understanding Allogrooming Through a Dynamic Social Network Approach: An Example in a Group of Dairy Cows

For gregarious species such as domestic cattle, the social environment is a very important determinant of their welfare and fitness. Understanding the complexity of cows' relationships can assist the development of management practices that are more integrated with the cows' social behavioral processes. The two aims of this study were: (1) to determine the dynamics of affiliative relationships, as indicated by allogrooming, by means of stochastic actor-oriented modeling, in dairy cows during early lactation; (2) to explore the underlying processes and the individual attributes, such as age, social rank and reproductive state, that could shape network pattern changes in grooming contacts between individual. We observed the allogrooming behavior of a dynamic group of 38 dairy cows for 4 h per day for 30 days. Using stochastic actor-oriented models, we modeled the dynamics of weekly contacts and studied how structural processes (e.g., reciprocity, transitivity, or popularity) and individual attributes (i.e., age, social rank, and reproductive state) influence network changes. We found that cows tended to groom individuals that had previously groomed them, implying a possible cooperation. Cows that groomed more actively did not appear to have a preference for specific individuals in the herd, and in return, tended to be groomed by fewer cows over time. Older individuals groomed more cows than younger ones, indicating that allogrooming could be related to seniority. Cows groomed mainly individuals of similar age, suggesting that familiarity and growing up together enhanced social grooming. Over time, cows with higher social rank were groomed by fewer cows and individuals recently reintroduced to the group groomed more herdmates. The study of social network dynamics can be used to better understand the complexity and non-linearity of cow relationships. Our findings, along with further research, can complement and strengthen the design of improved management practices that are more in line with the natural social behavior of cows.

Embryonic diapause in roe deer: A model to unravel embryo-maternal communication during pre-implantation development in wildlife and livestock species

An alarming number of large mammalian species with low reproduction rates is threatened with extinction. As basic knowledge of reproductive physiology is currently lacking in many species, increasing the understanding of reproductive physiology is imperative and includes the development of novel artificial reproduction technologies. Despite the relatively comprehensive knowledge on molecular mechanisms underlying reproduction in livestock species such as cattle, pregnancy failures are likewise far from understood. Contrary to other wildlife species, the European roe deer (Capreolus capreolus) displays a remarkably high pregnancy rate. In parts, cattle and roe deer exhibit comparable features of preimplantation embryo development. Therefore, understanding the high fertility rate in the roe deer holds a great potential for cross-species knowledge gain. As the only known species among the artiodactylae, the roe deer displays a long period of embryonic diapause. The preimplantation blastocyst reaches a diameter of 1 mm only at around 4 months compared to around 13 days post estrus in cattle. The expanded blastocyst survives in a uterine microenvironment that contains a unique set of yet unidentified factors that allow embryonic stem cells to proliferate at low pace without impairing their developmental potential. Upon reactivation, intimate embryo-maternal communication comparable to those reported in cattle is thought to occur. In this review, current knowledge, parallels and differences of reproductive physiology in cattle and roe deer are reviewed. The roe deer is proposed as a unique model species to (1) enhance our knowledge of fertility processes, (2) define factors that support embryo survival for an extended period, (3) advance knowledge on embryonic stem cells, and (4) unravel potential implications for the development of novel strategies for artificial reproductive technologies.

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

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.

The Influence of Different Types of Outdoor Access on Dairy Cattle Behavior

Pasture access for dairy cows is highly valued both by cows and the public at large. When pasture access is not feasible, farmers can provide cows with alternative forms of outdoor access, such as an outdoor bedded pack, that may be easier to implement on some farms. We reviewed the literature on how lying, standing, walking, feeding, social, and estrus behaviors are influenced by pasture and other types of outdoor areas. Pasture allows the expression of grazing and can facilitate the expression of lying, standing, walking, and estrus behaviors. In addition, pasture can decrease the number of negative social interactions between cows, likely because more space per cow is provided than what is normally available indoors. The provision of soft flooring and an open space in outdoor bedded packs appears to provide some benefits for lying, standing, and walking behavior and may also have positive effects on social behavior, especially with larger space allowances. The effects of an outdoor bedded pack on estrus behavior are less well-documented, but the provision of a standing surface that provides better footing than typically available indoors may promote estrus behavior. Alternative outdoor areas assessed to date appear to be less attractive for cows than pasture, perhaps because these areas do not provide the opportunity to graze. We encourage future research to investigate the importance of grazing for dairy cows. The motivation of dairy cows to access alternative outdoor areas should also be investigated. As cow preference for the outdoors depends on many factors, providing cows a choice may be of particular importance.

FOXL2 is a Progesterone Target Gene in the Endometrium of Ruminants

Forkhead Box L2 (FOXL2) is a member of the FOXL class of transcription factors, which are essential for ovarian differentiation and function. In the endometrium, FOXL2 is also thought to be important in cattle; however, it is not clear how its expression is regulated. The maternal recognition of pregnancy signal in cattle, interferon-Tau, does not regulate FOXL2 expression. Therefore, in the present study, we examined whether the ovarian steroid hormones that orchestrate implantation regulate FOXL2 gene expression in ruminants. In sheep, we confirmed that FOXL2 mRNA and protein was expressed in the endometrium across the oestrous cycle (day 4 to day 15 post-oestrus). Similar to the bovine endometrium, ovine FOXL2 endometrial expression was low during the luteal phase of the oestrous cycle (4 to 12 days post-oestrus) and at implantation (15 days post-oestrus) while mRNA and protein expression significantly increased during the luteolytic phase (day 15 post-oestrus in cycle). In pregnant ewes, inhibition of progesterone production by trilostane during the day 5 to 16 period prevented the rise in progesterone concentrations and led to a significant increase of FOXL2 expression in caruncles compared with the control group (1.4-fold, p < 0.05). Ovariectomized ewes or cows that were supplemented with exogenous progesterone for 12 days or 6 days, respectively, had lower endometrial FOXL2 expression compared with control ovariectomized females (sheep, mRNA, 1.8-fold; protein, 2.4-fold; cattle; mRNA, 2.2-fold; p < 0.05). Exogenous oestradiol treatments for 12 days in sheep or 2 days in cattle did not affect FOXL2 endometrial expression compared with control ovariectomized females, except at the protein level in both endometrial areas in the sheep. Moreover, treating bovine endometrial explants with exogenous progesterone for 48h reduced FOXL2 expression. Using in vitro assays with COS7 cells we also demonstrated that progesterone regulates the FOXL2 promoter activity through the progesterone receptor. Collectively, our findings imply that endometrial FOXL2 is, as a direct target of progesterone, involved in early pregnancy and implantation.

Hormonal therapy for ovarian dysfunctions in high-productive cows

The analysis was made of culling data in the farm of the Udmurt Republic. As a result, it was found that the animals are eliminated due to gynecological and limb diseases. They make up 19–24 % and 18–31 % respectively. Analyzing the results of gynecological clinical examination of cows, we found a predominance of ovarian diseases 32–36 %, as well as endometritis 28–30 %. The ovarian dysfunction progresses mostly. This can be attributed to an increase in the productivity of cows in the Udmurt Republic over the past 5 years from 5601 to 6250 kg per 1 cow. In connection with an increase in the incidence of ovaries, the calf yield per 100 cows decreases from 88 to 85 %. Causes of ovarian disease can be diseases of the birth and postpartum period. For the treatment of ovarian hypofunction, 3 schemes were used for anestral and reactive reproductive cycles. Often, the cause of ovarian hypofunction is uterine pathology; drugs that have a therapeutic effect on the uterus are included in the scheme.

System of prevention of gynaecological diseases in high-productive cows under in a farm in the Udmurt Republic

The purpose of the work is to develop a system for the restoration of the genital organs of cows after calving. We studied the therapeutic efficacy of drugs for the incidence of genital diseases of cows. The studies were conducted based on a complex of cattle of Black Motley breed at the facilities of Rico-Agro LLC in the Uvinsky district, Udmurt Republic. The average milk yield per lactation is 6250 kg. Most animals are susceptible to ovarian disease. The incidence of ovaries hypofunction increases annually. In the study of cows on the 60th day after calving, it was found that the uterus was ready for insemination in 86% of cows. However, the condition of the ovaries allows insemination of only 50% of the cows. The remaining animals needed treatment. The most common pathology was ovarian hypofunction. This is more common in highly productive cows and cows with a low body mass index. Three regimens for treating ovaries have been tested. The most effective Scheme 2 included Surfagon and an emulsion from ASD-2 and Tetravit. In the Scheme 2 group, 6 out of 8 cows were first successfully inseminated. It was established that using Estrofan on the first day after calving, it is possible to reduce the number of persistent corpus luteum.

Genomic merit for reproductive traits. II: Physiological responses of Holstein heifers

Fertility traits were recently added to the evaluation of genetic merit, allowing for the selection of Holstein cattle with improved reproductive performance. In the current study, we investigated the associations among genomic merit for daughter pregnancy rate (GDPR) and heifer conception rate (GHCR) and physiological responses during proestrus and diestrus. Holstein heifers (n = 99) were classified based on GDPR [high = 3.26 ± 0.76 (1.6 to 5.3), n = 48; low = -0.17 ± 0.75 (-1.8 to 1.0), n = 51] and GHCR [high = 2.75 ± 0.77 (1.5 to 5.5), n = 49; low = 0.06 ± 0.67 (-2.1 to 1.2), n = 50]. Heifers were fitted with an automated estrous detection device, were treated with PGF_2α for synchronization of estrus, and received either artificial insemination or embryo transfer at detected estrus. Blood was sampled at the time of PGF_2α treatment, within 24 h of the onset of estrus (d 0), and on d 7, 14, 19 ± 2, 28, and 35. Blood samples from all heifers were analyzed for concentrations of estradiol (d 0) and progesterone (on the day of PGF_2α treatment and d 0, 7, and 14). Blood samples from heifers pregnant on d 38 ± 3 were analyzed for concentrations of progesterone (d 0, 7, 14, 19 ± 2, 28, and 35), pregnancy-specific protein B (d 19 ± 2, 28, and 35), and insulin-like growth factor 1 (d 0, 7, 14, 19 ± 2, 28, and 35). Expression of mRNA for interferon-stimulated gene 15 in peripheral leukocytes isolated from blood collected on d 19 ± 2 was determined. Ovaries were scanned by ultrasound daily from d 0 to 4 or until ovulation was detected. Heifers with low GHCR tended to be less likely to be detected in estrus (78.0 vs. 91.8%). Estradiol concentration on d 0 was greater for heifers with high GDPR (4.53 ± 0.23 vs. 3.79 ± 0.23 pg/mL). The ovulatory follicle was larger for heifers with high GDPR (16.28 ± 0.33 vs. 14.55 ± 0.35 mm), whereas heifers with high GHCR tended to have smaller ovulatory follicles (15.00 ± 0.31 vs. 15.83 ± 0.37 mm). Heifers with high GDPR tended to be more likely to ovulate within 96 h of the onset of estrus (90.7 vs. 75.0%). Among heifers pregnant on d 38 ± 3, GDPR and GHCR were not associated with mRNA expression for interferon-stimulated gene 15. Heifers with high GDPR had greater concentration of pregnancy-specific protein B from d 28 to 35 (3.03 ± 0.15 vs. 2.48 ± 0.1 ng/mL). Heifers with high GHCR tended to have greater insulin-like growth factor 1 concentration from d 7 to 35 (108.0 ± 3.2 vs. 97.7 ± 4.2 ng/mL). Our results suggest that selection for Holstein cattle for GDPR may have positive effects on reproductive performance through changes in ovarian follicle development and steroidogenesis. Although selection of Holstein cattle for GHCR may negatively affect estrous expression by affecting ovarian follicle growth, selection for GHCR may improve reproductive performance by altering the somatotropic axis.

Evaluation of an ear-attached accelerometer for detecting estrus events in indoor housed dairy cows

Precision dairy farming technologies have tremendous potential to improve and support farmers in herd management decisions, particularly in reproductive management. Nowadays, estrus detection in cows is challenging and several supporting tools are available. In this study, a 3D-accelerometer integrated into an ear-tag (SMARTBOW, Smartbow GmbH, Weibern, Austria) was used for the detection of cows in estrus. Movement pattern based on accelerometer data were analyzed and processed by algorithms and machine learning, resulting in estrus alerts. For the evaluation of the system, reproductive performance data of 579 estrus events of multiparous cows were used to retrospectively evaluate the accuracy of estrus alerts generated by the accelerometer-based system and the overall performance of the system. Estrus events were classified as 'gold standard' events, if an estrus followed by AI resulted in pregnancy, and as 'recorded estrus' events, if two estrus events with an interval of 18-25 d were in the herd records, independent of whether estrus was followed by AI or pregnancy. In total, 316 'gold standard' events were matched with estrus alerts generated by the accelerometer-based system, resulting in a sensitivity of 97%. Furthermore, 263 'recorded estrus' events were compared with correct or incorrect estrus alerts by the system. Sensitivity, specificity, positive and negative predictive values, accuracy, and error rate for 'recorded estrus' events were 97%, 98%, 96%, 94%, 96%, and 2%, respectively. In summary, the SMARTBOW system is suitable for an automated detection of estrus events of multiparous cows in indoor housed dairy cows.

FSH in bovine superovulation

Bovine follicle stimulating hormone (FSH) is the hormone mainly used for superovulation treatments. It is used so that several secondary follicles can reach a dominant state at the same time and thus, treated cows can release up to ten or more ovules in each zeal, decreasing the generational interval and increasing livestock production. The hormones available in the current market are obtained mostly from pituitary extracts of swine and sheep, and although they are widely used. Several negative aspects have been reported, implying high risks of contamination with pathogens, contamination with other hormones that interfere with assisted fertilization processes, significant variations between each production batch and the decreased half-life that exhibit FSH leading to excessive handling of donor cows. In this review, we detail some new approaches to overcome these problems, like slow-release FSH formulations that have been developed in order to increase the half-life of FSH and, finally the use of recombinant DNA technology to ensure a pure product.

Fatty acid profile of milk for determining reproductive status in lactating Holstein Friesian cows

Large percentages of dairy cows do not express behavioural signs of oestrus. Faecal and urine fatty acid concentrations increase during oestrus. The objective of the present study was to determine the milk FA profile of dairy cows during the oestrous and dioestrous periods and the relationship with behavioural signs on the day of oestrus. The activity of 32 Holstein Friesian cows was measured continuously using GEA Rescounter ll pedometers (GEA Farm Technologies, Düsseldorf, Germany) and IceQubes (IceRobotics Ltd., Edinburgh, UK). Milk samples were collected on the day of oestrus and on day 14 of the subsequent oestrous cycle and analysed for FA concentration using gas chromatography (GC) and milk composition was also determined. All cows were artificially inseminated within 12 h of the onset of oestrus. On the day of oestrus, the concentration of acetic acid (P < 0.001), valeric acid (P = 0.016), caproic acid (P < 0.001) and myristoleic (P = 0.035) were greater in milk compared to day 14. On day 14 milk arachidonic acid concentration, however, was greater (P = 0.004) compared to the day of oestrus. Also, on day 14 arachidonic acid concentration was greater (P = 0.002) in non-pregnant compared to pregnant cows. In conclusion, the results of this study indicate there are changes in the concentrations of some milk FA during oestrus and dioestrus in lactating dairy cows.

Transcriptomics-genomics data integration and expression quantitative trait loci analyses in oocyte donors and embryo recipients for improving invitro production of dairy cattle embryos

In this paper we first provide a brief review of main results from our previously published studies on genome-wide gene expression (transcriptomics) in donor and recipient cattle used in invitro production (IVP) of embryos and embryo transfer (ET). Then, we present novel results from applying integrative systems genomics and biological analyses where transcriptomics data are combined with genomic data in both donor and recipient cattle to map expression quantitative trait loci (eQTLs). The eQTLs are genetic markers that can regulate or control the expression of genes in the entire genome, via complex molecular mechanisms, and thus can act as a powerful tool for genomic and gene-assisted selection. We identified significant eQTLs potentially controlling the expression of 13 candidate genes for donor cow quality (IVP parameters; e.g. cyclin B1 (CCNB1), outer dense fiber of sperm tails 2 like (ODF2L)) and 19 candidate genes for recipient cows quality (endometrial receptivity; e.g. ER membrane protein complex subunit 9 (EMC9), mannosidase beta (MANBA), peptidase inhibitor 16 (PI16)). Annotation and colocation of detected eQTLs show that some of the eQTLs are in the same genomic regions previously reported as QTLs for reproduction-related traits. However, eQTLs and the candidate genes identified should be further validated in larger populations before implementation as genetic markers or used in genomic selection for improving IVP and ET performance.

Perturbations in Lineage Specification of Granulosa and Theca Cells May Alter Corpus Luteum Formation and Function

Anovulation is a major cause of infertility, and it is the major leading reproductive disorder in mammalian females. Without ovulation, an oocyte is not released from the ovarian follicle to be fertilized and a corpus luteum is not formed. The corpus luteum formed from the luteinized somatic follicular cells following ovulation, vasculature cells, and immune cells is critical for progesterone production and maintenance of pregnancy. Follicular theca cells differentiate into small luteal cells (SLCs) that produce progesterone in response to luteinizing hormone (LH), and granulosa cells luteinize to become large luteal cells (LLCs) that have a high rate of basal production of progesterone. The formation and function of the corpus luteum rely on the appropriate proliferation and differentiation of both granulosa and theca cells. If any aspect of granulosa or theca cell luteinization is perturbed, then the resulting luteal cell populations (SLC, LLC, vascular, and immune cells) may be reduced and compromise progesterone production. Thus, many factors that affect the differentiation/lineage of the somatic cells and their gene expression profiles can alter the ability of a corpus luteum to produce the progesterone critical for pregnancy. Our laboratory has identified genes that are enriched in somatic follicular cells and luteal cells through gene expression microarray. This work was the first to compare the gene expression profiles of the four somatic cell types involved in the follicle-to-luteal transition and to support previous immunofluorescence data indicating theca cells differentiate into SLCs while granulosa cells become LLCs. Using these data and incorporating knowledge about the ways in which luteinization can go awry, we can extrapolate the impact that alterations in the theca and granulosa cell gene expression profiles and lineages could have on the formation and function of the corpus luteum. While interactions with other cell types such as vascular and immune cells are critical for appropriate corpus luteum function, we are restricting this review to focus on granulosa, theca, and luteal cells and how perturbations such as androgen excess and inflammation may affect their function and fertility.

Injectable progesterone in timed artificial insemination programs in beef cows

The aims of this study were I) to compare the follicular diameter, corpus luteum diameter and serum progesterone (P4) concentrations in cows treated with conventional protocol vs. injectable P4 protocol; II) to determine the serum P4 profile in ovariectomized heifers; and III) to compare pregnancy rate between protocols. In experiment I, multiparous cows received a protocol for ovulation synchronization with an intravaginal P4 device (n = 38; device + EB day 0; device removal + PGF2α + eCG + EC day 8) or injectable P4 (n = 38; injection + EB day 0; PGF2α + eCG + EC day 8). In experiment II, ovariectomized heifers (n = 8) were treated with injectable P4 and blood samples were collected to determine the serum P4 profile. In experiment III, multiparous cows were timed AI with two different P4 approaches, intravaginal P4 device (n = 48) or injectable P4 (n = 47). In the first experiment, cows treated with P4 device had higher (P < 0.05) diameter of dominant follicle after ovulation induction (11.6 ± 1.8 vs.10.3 ± 1.8 mm) and ovulation rate (97%, 37/38 vs. 47.3%, 18/38) than cows treated with injectable P4. But, the follicular growth daily was higher (P < 0.05) in cows treated with injectable P4 than intravaginal device (1.3 ± 0.4 vs. 1.0 ± 0.3 mm/day, respectively). In experiment II, the P4 concentration peak occurred within 48 hours (6.54 ng/mL) and decreased after 96 hours (P < 0.05) after P4 injection. In experiment III, cows with P4 device had higher (P < 0.05) pregnancy rate than the injectable P4 group (60.4 vs. 34.0%, respectively). These results demonstrate that although the intravaginal P4 devices showed a higher pregnancy rate, a protocol with injectable P4 represents an easier method and a promising alternative for TAI in cattle.