Estrus Synchronization Research Articles

A 12-year summary of the effects of estrous synchronization and body weight at breeding on reproductive success of Bos indicus-influenced beef heifers grazing warm-season grasses

A 12-year summary of the effects of estrous synchronization and body weight at breeding on reproductive success of Bos indicus-influenced beef heifers grazing warm-season grasses

Plasma progesterone profiles in ewes using different injectable progesterone formulations

Context The use of progesterone vaginal implants in sheep is frequently associated with vaginitis and adherences; and can hamper fertility in estrus synchronization programs. Aims The aim of this study was to characterize the plasma hormone profile induced by two injectable progesterone (iP4) formulations in ewes. Methods In Experiment 1, ewes received 20 or 40 mg of an iP4, with a third group as a control. In Experiment 2, 75 or 150 mg of a long-acting iP4 were administered, again with a control group. Key results In Experiment 1, progesterone concentrations remained at luteal levels for less than 24 h. The intervals from iP4 treatment to the onset of estrus and ovulation were greater in treated than in control ewes (P < 0.01). The proportion of ewes that ovulated within 8 days after treatment was lower in ewes that received 40 mg iP4 than in control ewes (P < 0.05). In Experiment 2, mean progesterone concentrations remained at luteal levels for 120 h. The interval from iP4 administration to estrus was longer in 150 mg treated ewes than in control ewes (P < 0.01). The interval from treatment to ovulation was longer in ewes treated with 150 mg than 75 mg and control ewes (P < 0.05). The proportion of ewes that ovulated was lower at 150 mg (P < 0.05). Conclusions The iP4 formula used in Experiment 1 could not maintain luteal levels for more than 24 h. The use of long-acting iP4 maintained plasma progesterone concentrations above luteal levels for at least 5 days. The long-acting treatment can therefore be tested for estrous synchronization treatments. Implications The long-acting progesterone may be an alternative to short estrous synchronization protocols.

Influence of hormonal treatments on progesterone levels to enhance embryo survival and kidding rates in goats.

This study investigated the efficiency of different estrous synchronization programs and hormonal treatments in improving reproductive outcomes in goats. Conducted on a commercial farm in southern Thailand, the study used multiparous Shami and Anglo-Nubian breed goats. In experiment 1, goats were randomly allocated to two estrous synchronization treatments: 11-day (CI11D) and 13-day (CI13D) intravaginal progesterone implants, followed by artificial insemination (AI) with frozen-thawed semen. Various hormonal treatments (human chorionic gonadotropin (hCG), GnRH analogue, progestogen) were administered on day 5 post-AI to elevate progesterone levels. Experiment 2 assessed embryo survival after transferring early- and late-stage embryos, using GnRH analogue to increase progesterone levels in the recipient goats. Results showed that GnRH analogue significantly increased pregnancy rates, kidding rates, and the number of kids born in the CI13D group. Progesterone levels were higher in treated groups, particularly with GnRH analogue, though estradiol levels varied between synchronization protocols. Late-stage embryo transfers significantly improved pregnancy rates and reduced embryonic loss compared to early-stage transfers. GnRH analogue supplementation reduced early embryonic mortality, enhancing embryo survival and overall reproductive performance. This study demonstrates the efficacy of tailored estrous synchronization and hormonal treatments in optimizing goat reproductive outcomes, with significant implications for improving fertility management in commercial goat farming. Although no significant differences were observed in progesterone levels, the administration of GnRH analogue reduced early embryonic mortality and improved reproductive outcomes, demonstrating its potential to enhance embryo survival and reproductive performance in goats.

Increased expression of Interferon-stimulated gene 15 (ISG15) in cervical cells on day 14 of pregnancy in Holstein heifers

In cattle, expression of interferon (IFN)-stimulated genes in the female reproductive tract has been reported as an early pregnancy diagnostic tool, as early as d 17 of pregnancy. The hypothesis of this study was that expression of ISG15 in the cervix of pregnant heifers is increased on d 14 of pregnancy. The objective was to compare the expression of ISG15 in cervical cells between pregnant and cyclic heifers (control, sham-inseminated) on d 14, 16, and 18 after insemination (d 0; D0). Holstein heifers were submitted to an estrus synchronization protocol and inseminated with extender only (“control,” n = 6), or with regular semen (n = 15). Heifers were classified as pregnant (n = 10) by ultrasound at D30 through the detection of a viable embryo with a heartbeat. Blood samples from the coccygeal vein were collected to determine serum progesterone concentrations on D14, D16, and D18. The expression of ISG15 and PGR in cervical cells collected through cytobrush was measured on D14, D16, and D18. A receiver operating characteristic (ROC) curve was calculated to quantify the pregnancy diagnostic accuracy of ISG15 and PGR expression. The expression levels of ISG15 in cervical cells were significantly greater in pregnant compared with control heifers on D14, and remained greater on D16 and D18, while differences in PGR were observed only on D18. Scatter plots and ROC analyses showed the most accurate prediction of pregnancy for ISG15 on D16. In conclusion, cervical cells express greater ISG15 mRNA in pregnant vs control heifers as early as D14 post-insemination, with the best accuracy on D16.

Reproductive Biotechnology Tools as a Game Changer for the Dairy Sector: The Case of Sexed Semen and Estrus Synchronization to Produce Seedstock Dairy Heifers

Human curiosity about the sexual orientation of living things has a long history. For thousands of years, livestock owners wanted to find a suitable way to predict the sex of the progeny to be born for their herds on their farm. Thanks to the development of semen sexing technology, animal breeding has undergone a revolution, which allows farmers to control the sex of their offspring. Sexed semen enhances overall productivity and also assists farmers in meeting the rising demand for high-quality dairy animals by enabling them to selectively generate seedstock female calves. The technology is a one-stop solution to enhance breed improvement especially in a country like Ethiopia where 97 percent of the cattle population is indigenous, which is not selected for milk production and results in undernourishment for animal source origin diet, including milk and meat. The benefits of using sexed semen include sex selection, improved genetic selection, enhanced breeding effectiveness, better control over herd dynamics, greater financial gains, environmental sustainability, and improved animal welfare. Hence, with the finding of this study, an overall result of a 98% response rate 95% female skewness, and 79% conception rate was recorded after being inseminated with sexed semen. The finding of the response rate is closer to the results reported by another researcher, while the average conception rate is comparatively higher. This could be due to careful animal selection, the use of fertile quality semen, proper heat detection, and inseminating at an optimum window of time. In general, from the piece of this study, it is possible to foresee and conclude that the adoption and application of sexed semen technology is a groundbreaking and game-changer technology for the dairy industry in a country like Ethiopia, which overcomes the limitations of improved crossbred dairy cattle, replacement heifers, and high milk prices on the one hand, a shortage of grazing land, ...

Heat stress: a major threat to ruminant reproduction and mitigating strategies.

Stress is an external event or condition that puts pressure on a biological system. Heat stress is defined as the combination of internal and external factors acting on an animal to cause an increase in body temperature and elicit a physiological response. Heat stress is a set of conditions caused by overexposure to or overexertion at excess ambient temperature and leads to the inability of animals to dissipate enough heat to sustain homeostasis. Heat exhaustion, heat stroke, and cramps are among the symptoms. For the majority of mammalian species, including ruminants, heat stress has a negative impact on physiological, reproductive, and nutritional requirements. Reproductive functions, including the male and female reproductive systems, are negatively affected by heat stress. It decreases libido and spermatogenic activity in males and negatively affects follicle development, oogenesis, oocyte maturation, fertilization, implantation, and embryo-fetal development in females. These effects lead to a decrease in the rate of reproduction and financial losses for the livestock industry. Understanding the impact of heat stress on reproductive tissues will aid in the development of strategies for preventing heat stress and improving reproductive functions. Modification of the microenvironment, nutritional control, genetic development of heat-tolerant breeds, hormonal treatment, estrous synchronization, timed artificial insemination, and embryo transfer are among the strategies used to reduce the detrimental effects of heat stress on reproduction. These strategies may also increase the likelihood of establishing pregnancy in farm animals.

Effect of Different Protocols of Estrus Synchronization on Vaginal Microflora with Antibiotic Susceptibility to Bacteria

To investigate the effect of different protocols for estrus synchronization in ewes on the vaginal tract bacteria and evaluate the sensitivity of bacteria to different antibiotics. Sixteen local breed ewes were allocated to four groups, each containing four. Group A: ewes treated with sponges for 10 days; Group B ewes treated with CIDR for 10 days; Group C ewes treated with sponges for 14 days and finally Group D ewes treated with CIDR for 14 days. Sterile swaps were taken from the vaginaʼs mucous before insertion of sponge or CIDR and after removing it for each group. Vaginal swabs from synchronized ewes were obtained from the vaginaʼs mucous before insertion of sponge or CIDR and after removing it for each group to use in different bacteriological tests. The results showed that the most dominant bacteria were E-Coli 7/7 (100%), and Staphylococcus aureus (71%) before insertion, while in group A, the percentage was 75% and 100% for E-Coli only in group B and group C respectively. According to E-coli, the results showed that it was more sensitive to Doxycycline (3.36±0.3), Enrofloxacin (3.23±0.2), and Ciprofloxacin (3.18±0.3) figure (2). Also, Staphylococcus aureus was sensitive to Doxycycline (3.32±0.4), Enrofloxacin (3.17±0.3), and Ciprofloxacin (3.12±0.3). It was concluded that the E-coli was the most prominent microflora in the vagina in ewes before and after insertion of sponges. Doxycycline, Enrofloxacin, and Ciprofloxacin are the most effective antibiotics against E-coli and Staphylococcus aureus.

Success of Artificial Insemination in Rural Area Cows

Biotechnologies of reproduction like artificial insemination were identified as a mean to intensify the local production. Therefore, some factors are still responsible to the failure of their applications in rural area. This survey was conducted from April to June 2023, to evaluate the effects of age, body weight, body condition score (BCS), calving rank, postpartum to artificial insemination interval and feed complementation on the success rate of artificial insemination in females Goudali. Thus, activities took place at two peri-urban livestock farms in the town of Ngaoundéré, in the Adamaoua region of Cameroon where 34 cows were concerned. The selected cows have an average of 8.21±2.41 years old, a body weight of 343±52.28 kg, a body condition score of 3.23±0.55, a calving rank of 2.21±1.22 and a postpartum to insemination interval of 4.39±1.40 months. The induction and synchronization of estrus were carried out based on the PRID-PGF2α-PMSG protocol which allowed to obtain a synchronization rate of 97.06% and the insemination were done 56-57 hours after the previous operation, with an imported semen of Brahman bull. During rectal palpation and early pregnancy diagnosis based on progesterone level measurement, the result shown that, 20 cows out of 33 inseminated were pregnant. The success rate of artificial insemination recorded was 60.6%. Amongst all the studied factors, analysis shown no significant (P> 0.05) effect on the success rate after artificial insemination. Thus, recommendations were made to popularize the use of artificial insemination and early pregnancy diagnosis test as a mean to improve reproductive performances of local farms. However, studies must be done to evaluate the cost of their applications in rural areas.

Adipokine concentrations in sheep with experimental pregnancy toxemia. A randomized, controlled clinical trial

Pregnancy toxemia (PT) is a metabolic disease of small ruminant that develops during the last period of pregnancy and can cause death. Considering the high mortality rate, early diagnosis of the disease is important to minimize economic loss. Thus, this study aimed to investigate the concentrations of some adipokines (Leptin, Apelin, Resistin) and some other biochemical parameters for their role in the diagnosis and prognosis of PT. Fifty Kangal ewes that were between the ages of 2–4 year–old, were used in the study. The animals included in the study were subjected to estrus synchronization. Rams were introduced to all ewes subjected to synchronization. Pregnancies were diagnosed with ultrasonography on the 25th, 60th, and 110th days (d) following matings. Sixteen ewes bearing twin fetuses, whose fetal viability continued, were included in the study after general examinations. The ewes were maintained under grazing conditions in the first 110 d of gestation. At the end of the 110th d, 16 twin–bearing pregnant ewes were randomly divided into two groups (Control and PT). Ewes in the control group were fed to meet the nutritional requirements. the experimental PT group ewes were fed with equivalent to 50% of the daily needs for 20 d (120–140) and then fasted for 72 hours (141–143). During study blood samples were taken via jugular vein every 5 d from the 120th d to the 140th d. BHBA, glucose, Leptin, Resistin, Insulin and Apelin were measured in the blood samples. Liver biopsy samples were collected twice from all ewes on the 120th and 143rd d. As a result, in group PT, BHBA and leptin concentrations have been increased significantly while glucose levels significantly reduced. Resistin, Insulin and Apelin concentration were similar in both groups. In conclusion, it was concluded that monitoring BHBA, glucose and leptin in PT may be useful in diagnosis and prognosis.

Impact of heat stress on female reproduction in farm animals: challenges and possible remedies

Global warming poses significant challenges to agriculture, particularly within the livestock industry. Heat stress in animals refers to the physiological and metabolic distress experienced when environmental heat causes an animal’s body temperature to exceed its thermoneutral zone. Heat stress has a significant detrimental impact on reproductive outcomes, posing a direct threat to the profitability of livestock operations. Heat stress disrupts the normal hormonal balance essential for reproduction in female livestock, adversely affecting events of folliculogenesis and embryogenesis. As a result, the developmental competence of oocytes is compromised, which is crucial for successful fertilization and reproduction. Consequently, heat stress can lead to issues such as immature oocytes, atypical or sluggish embryonic development, silent estrus, and increased pregnancy loss causing a decline in reproductive rates and livestock owners face substantial financial losses. Despite using various cooling strategies, such as water sprinkler systems, cooling shades, and cooling devices, these measures are often insufficient to restore normal reproductive rates. Therefore, it is crucial to implement and explore novel strategies to enhance reproductive efficiency during periods of heat stress. Potential mitigation techniques include estrus synchronization, artificial insemination, hormonal alterations, embryo transfer, genetic engineering, sophisticated breeding strategies, the use of nutraceuticals, and changes in management practices. This review aims to consolidate recent findings on the adverse effects of heat stress on female reproduction, especially in tropical environments, and to evaluate potential strategies for improving summer fertility of livestock. Bangladesh Journal of Animal Science 53(3): 77-100, 2024

Reproductive Response of Hair Sheep to Short or Long Duration Estrus Synchronization Protocols

Objective: Evaluate the reproductive response of hair ewes treated with estrus synchronization protocols that included a progesterone-releasing intravaginal device (CIDR) for a period of 7 or 12 days. Methodology: During the end of winter, ewes were randomly allotted to one of two estrus synchronization protocols: 1) Short-term protocol (SD), ewes (n=24) received a CIDR on Day 1 and removed on Day 7, and received 400 IU of equine chorionic gonadotropin (eCG) and 0.125 mg of cloprostenol; 2) Long-term protocol (LD), ewes (n=24) received a CIDR on Day 1, retired on Day 12 and received 400 IU eCG. Ewes showing estrous behavior were bred with a mature ram. Results: There were no differences (P>0.05) in the estrus response in both groups of ewes (100 vs 95.8% for SD and LD, respectively), the pregnancy rate (87.5 vs 87.5%), prolificacy (1.95+0.1 vs 2.2+0.1 lambs/ewe), hours between CIDR removing and the beginning of estrus (34.4+8.1 vs 34.8+9.2 h), and estrus duration (39.7+2.9 vs 39.9+4.7 h). At CIDR removal, ewes in the PL group showed a greater diameter (P<0.05) for the largest follicle in both ovaries (5.42+0.3 and 5.42+0.4 mm for the follicle in the left and right ovaries, respectively) vs PC ewes (4.25+0.1 and 4.29+0.1 mm). Limitations of study: Results observed in the follicle diameter could be due to low circulating progesterone levels in the LP group, which must be confirmed in future studies. Conclusions: The short protocol for estrus synchronization can be used in hair ewes under temperate conditions, without affecting their reproductive response.

PSVI-24 Gene expression profiles of granulosa and peripheral white blood cells from fertile and sub-fertile beef heifers

Abstract Beef heifer fertility issues contribute to a major economic loss in the cow-calf production industry. Therefore, identifying beef heifers with superior genetic potential for improved fertility would increase profitability. This study aimed to identify differences in the transcriptome profiles from granulosa and peripheral white blood cells (pWBCs) of beef heifers with varying reproductive potential. For this, Angus-Simmental crossbred heifers were subjected to an estrus synchronization and fixed-time artificial insemination (AI) protocol (7-D CO-Synch + CIDR) followed by exposure for 60-d to a fertile bull. Depending on the presence or absence of conceptus 120 d post-AI, heifers were classified as fertile (pregnant by AI) or sub-fertile (non-pregnant by AI or bull-breeding). Pregnancies were terminated, and all animals in both groups (fertile, n = 8; and sub-fertile, n = 5) were cycling when the blood and ovaries were collected from each heifer. Total RNA was extracted from the pWBCs and granulosa cells and subjected to library preparation and sequencing on the Nova-Seq platform. The read counts were obtained after data quality control using FastQC v0.11.9 and MultiQC v1.12 and alignment to the Ensemble’s ARS UCD1.2 Bos taurus genome reference using STAR aligner v2.7.5. The filtered data were subjected to differential expression analysis using DESeq2. We identified 1,061 and 72 significantly differentially expressed genes (DEGs) with P-values ≤ 0.05 and absolute (log2 fold change) ≥ 0.5 from pWBC and granulosa, respectively. Notably, 12 targets including 9 protein coding genes (PLCL1, DNER, GNAS, CDH3, PER1, ITGA2B, CXCL12, ENSBTAG00000048613, ENSBTAG00000051519), bta-mir-2887-1, 5-8S-rRNA and U5 were found as DEGs in both the tissues. Based on a differential co-expression analysis using PCIT, we identified GNAS and DNER as hub genes in pWBC and the granulosa cells of the sub-fertile heifer group. The 12 shared genes were over-represented for pathways such as NF kappa B and chemokine signaling, regulation of actin cytoskeleton, and platelet activation. Some of the identified genes have been previously associated with fertility, while others are novel. A detailed understanding of the underlying biological mechanisms of the top genes and a follow-up study with a larger sample size at different time points could validate the candidates identified in this study for their role as potential therapeutic targets.

PSIII-2 Exploring differential gene expression and pathways associated with pregnancy outcomes in beef heifers

Abstract Heifer fertility is a key factor in the success of beef production systems, as the reproductive performance of a heifer correlates with her stayability in the breeding herd. However, despite being reproductively mature and physically healthy, 5 to 15% of these heifers fail to conceive within a designated breeding season. The underlying physiological mechanisms preventing these heifers from achieving pregnancy remain elusive. Therefore, this study aimed to determine differentially expressed genes (DEGs) and biological pathways associated with pregnancy outcomes in beef heifers. Angus-Simmental crossbred heifers were subjected to an estrus synchronization and fixed-time artificial insemination (AI) program (7-d CO-Synch + CIDR) and blood samples were collected at the time of AI for isolation of peripheral white blood cells (PWBC). After pregnancy check, heifers were classified as pregnant (P) and non-pregnant (NP). Based on that, 6 animals per group were randomly selected for total RNA isolation from the PWBC samples, and genome-wide expression was measured through RNA sequencing. The RNA-Seq data were analyzed using an in-house bioinformatics pipeline, with filtered reads aligned to the Bos taurus reference genome using STAR. DEGs were identified using DESeq2, followed by functional analysis using ShinyGO. Our approach unveiled 230 DEGs, comprising 102 up and 128 downregulated genes in the NP group (P-value ≤ 0.05 and |log2FC| > 0.5). Upregulated genes included those from the cytochrome P450 superfamily (CYP27B1 and CYP2U1). The genes SCML2, USIG2, and FBP1 were upregulated and have been associated with immune response and increased PWBC counts. This may be related to the over-representation of biological processes involved in cell division based on the upregulated genes. KEGG pathway over-representation analysis of DEGs retrieved allograft rejection, graft-versus-host disease, type I Diabetes Mellitus, insulin signaling pathway, and transcriptional misregulation of cancer. These pathways included genes such as BOLA-DQB, PRKAR1B, CALML4 and JUP, which were reported as downregulated during times of inflammatory response. Another downregulated gene was GZMB, which is needed for proper cell targeting during immune response. This finding may provide a link between immune function and early pregnancy failure. However, the relationship between the immune system and pregnancy warrants further investigation. Our results shed light on the molecular mechanisms underlying reproductive performance in beef heifers and support previous studies associating immune function with pregnancy outcomes. These differentially expressed genes may be further explored as potential avenues for enhancing fertility in beef production systems.

PSVII-13 Influence of early maternal gestational body weight gain on liver gene expression across generations in offspring

Abstract Maternal nutrition in the periconceptional period influences gene regulation in the fetal liver across generations, affecting long-term metabolism. This study aimed to examine the effects of the rate of body weight (BW) gain of the dam (F0) during early gestation on the differential gene expression of the liver of first (F1) and second-generation (F2) offspring. Crossbred Angus heifers (F0) were assigned into two groups based on their targeted rate of BW gain during the first 84 d of gestation: low gain (LG; 0.28 kg/d; n = 8) or moderate gain (MG; 0.79 kg/d; n = 8). Following this period, all heifers (F0) were kept on a forage-based diet until the F1 offspring were weaned at 8 mo. The F1 heifers underwent estrus synchronization and were artificially inseminated at 15 mo of age. Liver samples were obtained from the F1 heifers at birth and later when harvested at 84 d of gestation, along with liver samples from their F2 fetuses, for a comprehensive multigenerational RNA-Seq analysis. Differentially expressed genes (DEGs) were identified using the DESeq2 R-package, focusing on significant genes determined by a P-value ≤ 0.05 and a log2 fold change |0.5|. Metabolic pathways and biological processes were analyzed using the WebGestalt tool to understand the implications of the observed gene expression changes. At birth, F1 heifers from MG dams exhibited 281 DEGs, comprising 152 downregulated and 129 upregulated genes compared with the offspring of LG dams. These genes were over-represented in lipid metabolism, cellular homeostasis, and signaling pathways, such as MAPK and chemokine signaling. At harvest, 159 DEGs were identified in F1 heifers, with 67 genes downregulated and 92 genes upregulated in the MG group. These genes were related to cellular morphogenesis and biogenesis processes, with a notable downregulation of metabolic pathways. For the F2 fetuses, 192 DEGs were identified, where 71 genes were downregulated, and 121 genes were upregulated. These genes were involved in biological functions such as peptide secretion to cell proliferation and signaling pathways, including PI3K-Akt and Hippo signaling. The analysis of DEGs shared between F1 heifers and F2 fetuses highlighted the influence of the moderate BW weight gain of the F0 dams. At birth and harvest, F1 heifers shared three genes (NAV2, FAM131C, SH3D21). F1 heifers at birth and F2 fetuses shared five genes (CD3E, H1-12, SLC7A11, PIP4P2, ENSBTAG00000051730). From the harvest at d 84 in F1 heifers and F2 fetuses, five genes were shared (DCDC2, RIN1, ENSBTAG00000008911, ENSBTAG00000040518, ENSBTAG00000048049). No DEGs were shared across all comparisons. These findings emphasize the multigenerational impact of early gestational BW gain of the dam on liver gene expression, influencing metabolic pathways and signaling across generations.

227 Moderate body weight loss reduces total antioxidant capacity in pregnant beef heifers and one-carbon metabolite supplementation does not mitigate this response

Abstract In beef heifers, body weight (BW) gain and physiological stress are important considerations for reproductive outcomes and whole herd production efficiencies. The objective of this study was to determine if dietary one-carbon metabolite (OCM) supplementation in moderate BW loss pregnant heifers alters circulating total antioxidant capacity, superoxide dismutase, and glutathione peroxidase activity. In a replicated 2 × 2 factorial, Angus-cross heifers (n = 81) were stratified by BW to gain 0.45 kg/d (CON) or lose 0.23 kg/d (RES) and receive corn carrier with OCM supplements (+OCM) or without (−OCM). The OCM supplements consisted of vitamin B12 (20 mg) and folate (320 mg) injections weekly and dietary rumen-protected methionine (7.4 g/d) and choline (44.4 g/d) from breeding (d 0) to d 63 of gestation. The four treatment groups were: CON−OCM (n = 20), CON+OCM (n = 21), RES−OCM (n = 21), and RES+OCM (n = 19). Heifers underwent estrus synchronization and were bred via artificial insemination using female sexed semen to a single sire. Pregnancy was diagnosed and fetal sex was verified on d 35 of gestation. Blood was collected and assayed for total antioxidant capacity, superoxide dismutase, and glutathione peroxidase activity on d −2 (baseline), 35, and 63 of gestation for all three replicates. Data were analyzed using the MIXED procedure of SAS with repeated measures to determine the effect of gain, supplement, day, and their two-way and three-way interactions. The gain × supplement interaction remained in all models, but other interactions were removed if P > 0.10. Replicate and heifer BW were included in the model as covariates and covariance structure was determined by lowest AIC and BIC. Statistical significance was considered at P ≤ 0.05 and tendencies at 0.05 < P ≤ 0.10. There was no BW gain × supplement interaction, or main effect of OCM supplements in total antioxidants. There was a gain × day effect (P ≤ 0.01), in which total antioxidants were increased on d 35 and further increased on d 63 in CON compared with RES treatments. There was no gain × supplement interaction, or main effect of gain or OCM supplements in superoxide dismutase and glutathione peroxidase. However, both superoxide dismutase and glutathione peroxidase were decreased (P ≤ 0.01) on d 63 compared with d 0 and 35. These data suggest that moderate BW loss reduces total antioxidant capacity in pregnant beef heifers, which could affect redox homeostasis. However, OCM supplements did not affect total antioxidant capacity, superoxide dismutase, or glutathione peroxidase. These findings are somewhat surprising considering oxidative stress has been well characterized in nutrient-restricted pregnancies, and given the interconnection between energy metabolism and one-carbon metabolism. Future research is warranted to fully elucidate the therapeutic effects of one-carbon metabolites.

Study on the Technology of Laparoscopic Ovum Pick-Up and In Vitro Embryo Production in Chongming Goats.

The application of laparoscopic ovum pick-up (LOPU) and in vitro production of embryos (IVEP) technologies has opened up a new path for purebred breeding and breed improvement in goats. However, due to the complexity of the procedures and multiple influencing factors, these technologies have not been widely adopted in goat production. This study explores factors affecting the efficiency of LOPU in goats by comparing the use of controlled internal drug release (CIDR) for estrus synchronization, conventional FSH versus long-acting recombinant ovine FSH (R-FSH) for superovulation, and the timing of LOPU at 48 h, 60 h, and 72 h of follicular development. The metrics evaluated included the recovery rate of cumulus-oocyte complexes (COCs), the average number of ovarian follicles, the average number of COCs, and the average number of available COCs. The results demonstrated that the efficiency of LOPU was significantly higher with two doses of R-FSH compared to the conventional FSH superovulation protocol and the control group (p < 0.05), with two doses of R-FSH providing a higher LOPU efficiency than one dose (p < 0.05). Using CIDR for estrus synchronization showed no significant difference in LOPU efficiency compared to the non-CIDR group. Similarly, the efficiency of LOPU showed no significant difference between the hormone treatments at 48 h, 60 h, and 72 h. By exploring and optimizing the factors influencing LOPU, we ultimately established a LOPU technology system for goats that meets the production needs of small ruminants.

RNA Sequencing Reveals the Involvement of Serum Exosomal miRNAs in Early Pregnancy in Cattle.

Low fertility is the main cause of the low productivity in beef cattle and is mainly associated with a lack of conception after fertilization. The establishment of early pregnancy in cattle is a complex physiological process, and embryo implantation is crucial for the successful establishment of pregnancy. Exosomal miRNAs play an important role in regulating mammalian embryo implantation and development. This study used synchronous estrus technology to extract exosomes from bovine serum at 0, 14, and 21 days of early pregnancy and analyzed the expression profile of exosomal miRNAs through RNA-seq technology. We identified 472 miRNA precursor sequences and 367 mature miRNA sequences in the three sample groups, with the majority of the miRNAs having high abundance. Differentially expressed miRNAs (DEmiRNAs) were screened, and 20 DEmiRNAs were obtained. The differential expression analysis results show that compared to day 0, there were 15 DEmiRNAs in the serum on day 14 and 5 on day 21 of pregnancy. Compared to the 14th day of pregnancy, there were eight DEmiRNAs in the serum on the 21st day of pregnancy. Bioinformatics analysis shows that the target genes of DEmiRNAs regulated the signaling pathways closely related to early pregnancy, including the VEGF, NF-κB, and MAPK signaling pathways. In addition, the newly discovered miRNAs were bta-miR-3604, bta-miR-2889, bta-miR-3432a, and bta-miR-409b. These results provide a theoretical reference for screening the molecular markers for early pregnancy establishment and maternal recognition of pregnancy (MRP) in cattle and new ideas for shortening the calving interval in cows.

Impact of Short-Term of Estrous Synchronization on Some Reproductive Performance Characteristics in Awassi Sheep

Impact of Short-Term of Estrous Synchronization on Some Reproductive Performance Characteristics in Awassi Sheep

Buserelin Acetate Added to Boar Semen Enhances Litter Size in Gilts in Tropical Environments.

The use of exogenous hormones has long been of interest for improving reproductive performance in swine production. Enhancing litter size directly impacts the economic efficiency of pig production. Various strategies, including nutritional, genetic, and hormonal approaches, have been explored with varying degrees of success. Administering a gonadotropin-releasing hormone (GnRH) agonist, such as buserelin, at the onset of estrus can induce ovulation and reduce the variation in ovulation timing among sows. This study assessed the impact of GnRH agonist supplementation in boar semen doses on the litter size of inseminated gilts. The research was conducted on a commercial swine herd in northern Thailand. A total of 231 Landrace × Yorkshire crossbred gilts, aged 224.5 ± 16.2 days at the onset of estrus synchronization, participated in the experiment. The gilts' estrus was synchronized with oral altrenogest supplementation at a dosage of 20 mg/day for 18 days. After exhibiting standing estrus, the gilts were randomly divided into three groups. Control group: gilts were inseminated at 0 and 12 h post standing estrus onset with a conventional semen dose (n = 94). Treatment 1: similar to the control group, but with an added 5 µg (1.25 mL) of buserelin acetate to the boar semen dose during the first insemination (n = 71). Treatment 2: similar to the control group, but with 10 µg (2.5 mL) of buserelin acetate added to the boar semen dose during the first insemination (n = 66). All gilts were inseminated twice during their standing estrus using the intrauterine artificial insemination method. Each semen dose contained 3.0 × 109 motile sperm in 80 mL. The farrowing rate averaged 78.8% and did not significantly differ between the groups (p = 0.141). The total number of piglets born per litter in the treatment 2 group was greater than in the control group (14.0 ± 0.3 vs. 13.2 ± 0.3, respectively, p = 0.049), but was not significantly different from the treatment 1 group (13.3 ± 0.3, p = 0.154). Similarly, the number of live-born piglets in the treatment 2 group was greater than in the control and treatment 1 groups (13.2 ± 0.4 vs. 12.3 ± 0.3 and 12.0 ± 0.4, respectively, p < 0.05). Moreover, the live-born piglets' litter birth weight in the treatment 2 group was greater than in the control group (17.0 ± 0.4 vs. 15.6 ± 0.3 kg, respectively, p = 0.008) and the treatment 1 group (15.7 ± 0.4 kg, p = 0.025). In conclusion, adding a GnRH agonist to boar semen appears to enhance the litter size of gilts. Further research should focus on understanding the underlying mechanisms and determining the optimal dose and timing for GnRH agonist supplementation.

Is it possible to replace eCG by GnRH in the hormonal protocol for timed artificial insemination in ewes during the breeding season?

Hormonal protocols based on progestogens and equine chorionic gonadotrophin (eCG) are efficient for estrus and ovulation synchronization in ewes. Although eCG is indispensable during seasonal anestrus, it may not be necessary during the breeding season. Thus, we tested the hypothesis that GnRH is effective in replacing eCG during the breeding season allowing satisfactory ovulation rate, luteal function and conception rates after timed artificial insemination (TAI). Ewes (n = 134) with a minimum body condition score of 2.5 (0–5 scale) were treated with intravaginal devices (IVD) containing 60 mg of medroxyprogesterone acetate (MPA) for seven days and received 0.26 mg of sodium cloprostenol at the time of IVD removal. In Exp. 1, at IVD removal, ewes (n = 29) were allocated to three groups: eCG (200 IU at IVD removal; n = 10); eCG+GnRH (200 IU eCG at IVD removal and 4 µg of buserelin 36 h later; n = 10); or GnRH (buserelin 36 h after IVD removal; n = 9). Blood samples were collected 2, 6 and 12 days after TAI moment (54 h after IVD removal), for progesterone (P4) analysis. In Exp 2, the ewes were allocated to eCG (n = 10) or GnRH (n = 10) groups, as above described, and ovulation moment was evaluated 54, 66 and 78 h after IVD removal. In Exp 3, TAI was performed in ewes from eCG (n = 45) and GnRH (n = 40) groups using 100 × 106 motile spermatozoa from a pool of semen collected from four rams. In Exp. 1, based on P4 levels, we confirmed that all the ewes ovulated (29/29) and there was no significant effect of group (P = 0.89) or group x day (P = 0.18) on P4 concentration, being observed a significant effect of day (P = 0.0001). In Exp. 2, the maximum DF diameter (P = 0.26) and ovulation moment (P = 0.69) did not differ between groups. In Exp. 3, pregnancy rate was significantly lower (P = 0.02) in GnRH (22.5 %; 9/40) compared to eCG (46.7 %; 21/45). The results indicate that, although ovulation and luteal function were not altered after eCG, eCG+GnRH or GnRH treatment, GnRH alone before TAI cannot be used to replace eCG treatment during the breeding season.