Recipient Cows Research Articles

Validation of Hand Grading Technique of Corpora Lutea in Embryo Recipient Cows

The success of embryo transfer in cattle may depend on several factors. The blood progesterone level of the embryo recipient would be one of the main factors secondary to the size and quality of the corpus luteum. Per-rectal palpation and by-hand grading of corpora lutea have been practiced routinely, even under commercial embryo transfer programs in cattle. This experiment aimed to evaluate the accuracy of the per-rectal hand grading technique of mid-phase corpora lutea in embryo recipient cows. A group of healthy cows (Friesian× Jersey, n=25), which had been selected as recipient animals with the special consideration of reproductive history in an embryo transfer program, was used in this study. Estrous of those animals were synchronized using a standard progesterone intravaginal devise-PGF2α protocol. Conven-tional evaluation and grading of corpora lutea were conducted at the per-rectal hand grading as 'A', 'B', 'C' and 'Cystic' (If diameters; < 1cm=C, 1-1.9cm=B, 2-2.5cm= A, >2.5cm= Cystic). In this study, the accuracy of those hand-grading techniques was evaluated using ultra-sound scanning technology on the same day. Identification accuracy of grades C, B, A, and Cysts in hand grading technique was 45%, 56%, 67%, and 50%, respectively. The average accuracy in the hand grading technique was 52%, and identification accuracy as suitable (A or B) corpora lutea for embryo transfer was 76%. Results raised the 24% probable loss of embryo transferrable recipients due to the hand-grading technique. Further, 8% of unsuitable cows can be selected as embryo recipients due to the practice of hand-grading techniques at embryo transfer programs. Although higher accuracy is a characteristic of the hand grading technique, the technology causes considerable loss due to inaccurate selection probability of recipients at embryo transfer programs.

Evaluation of intrinsic and extrinsic factors affecting pregnancy rate in dual-purpose cows under tropical conditions.

Embryo transfer (ET) in bovines was created with the purpose of increasing the pregnancy rate (PR) of animals with high genetic value; however, multiple factors have been found to affect the success of this reproductive biotechnology. These factors are frequently grouped in intrinsic and extrinsic factors. Thus, the objective of the present experiments was to assess the effect of intrinsic and extrinsic factors on the pregnancy rate under tropical conditions. To do this a total of 648 embryo transfer (ET) procedures were performed between January and December 2021. The intrinsic factors were size and location of the corpus luteum, body condition, genetic group, age and parity; while extrinsic factors were location of the farm, environmental comfort, season in which the ET was carried out, prevailing weather conditions, and the preservation, quality, and the development stage of embryos at the time of ET. A χi2 was used for analysis of main effects, and logistic regression analysis to calculate the probability of pregnancy and the association between intrinsic or extrinsic factors; additionally, a multivariate analysis of data clusters was used to find a linkage between the effects. While recipient female age had a negative effect (Odds ratio = 0.345-0.871) on PR (p < 0.05), being higher in younger cows, the rest of the intrinsic factors did not affect the PR. The significant (p < 0.05) extrinsic factors were THI category, season of year and type of embryo preservation, showing that the highest PR (p < 0.05) was obtained in the comfort THI category, during the winter season and using fresh embryos for transfer. The clustering analysis did not show any linkage between PR and intrinsic factors, while a linkage (p < 0.05) was found with season of the year and embryo preservation as extrinsic factors. It is concluded that age of the recipient cow and environmental conditions at the time of the embryo transfer are key factors to be considered for a successful pregnancy rate from in-vitro ET programs using dual-purpose cows under tropical conditions.

Birth of First In vitro Produced Calves in Bangladesh and Their Reproductive Fitness

The goal of the current study is to produce calves by implanting recipient cows with in vitro generated embryos. For in vitro maturation, slaughterhouse-driven cumulus-oocyte-complexes (COCs) with an even cytoplasm and at least three layers of compact cumulus cells were chosen (IVM). For the purpose of in vitro fertilization, capacitated fresh spermatozoa and presumed matured COCs were co-cultured for 18 to 20 hours (IVF). Cumulus cells were removed by carefully pipetting them into TL-HEPES. The zygotes spent three days in an in vitro culture (IVC) droplet. After this initial phase of culture, the 8–32 cell embryos were moved to IVC-II media, where they remained until Day 8 of development. On day 8, these embryos were transferred into recipient cows, with two embryos transferred to each of the five recipient cows. On day 60 of embryo transfer (ET), rectal palpation was used to assess pregnancy followed by ultrasonography on day 90. Out of five recipients, one cow delivered twine calves with a pregnancy rate of 20%. The calves were named Falguni and Chaitali. The duration of gestation was 277 days. Falguni weighed 12.87 kg at birth, whereas Chaitali weighed 18.59 kg. Falguni and Chaitali both showed typical growth patterns, with an average 254.77 g and 463.15 g/day. At a regular age, both heifer calves reach puberty and give birth. This research emphasizes the possibility that ovocytes from slaughterhouse ovaries can be used to produce healthy IVP calves, which would be a major step forward in Bangladesh’s fast expansion of high-yield dairy cattle.

Survival and Development of in Vivo Produced Boran and Boran* Holstein Cross Embryos

One of biotechnology technique that is frequently used to enhance the number of animals with superior genetic ability and high productivity is embryo transfer. Embryos can be obtained in vivo or in vitro, and they can be frozen and then thawed before being delivered to the recipient animals. Conception rates are influenced by a number of variables, including the quality and developmental stage of the embryo, the location of the embryo&amp;apos;s deposit in the uterus, the degree of difficulty of the transfer, whether to use a fresh or frozen embryo, the operator&amp;apos;s experience, the corpus luteum&amp;apos;s quality, whether to use a heifer or a cow, and the time of year the transfer occurs. The fertility of domestic animals is severely impacted by early embryonic death. For this reason, this study was carried out to gather data on early embryonic development that is normal, the amount and timing of embryonic mortality, potential endogenous and exogenous causes of embryonic loss, and to develop strategies to lower embryonic mortality. A total of 40 embryos (20 fresh and 20 frozen, 26 quality grade 1 and 14 quality grade 2, 29 compact Morula stage and 11 early Blastocyst stage) were transferred to 40 recipient cows (22 Boran and 18 H-B cross) with different body condition score. Return to heat was used as method of pregnancy diagnosis and all recipients were followed around day 14 post embryo transfer and 14 animals were shown heat sign, the rest 26 animals were suspected for pregnancy (65%). Using ultrasound, a pregnancy diagnosis was made on day 45, and 20 recipient animals were found to be 50% positive for PD. On day 60, PD positive animals were re-examined with ultrasound and only 10 were confirmed as PD positive (25%). The PD negative on day 45 and day 60 were suspected to be early embryonic mortality. Other pregnancy loss occurred in this study was abortion nearly after five month of pregnancy. It is not doubtful that, the technique of embryo transfer is utilized to increase the reproductive rates of important female animals. However, it needs proper management for both donor and recipient animals. Therefore, for the successful application of the technology optimum level of feeding both quantity and quality, health management and conducive environment should be fulfilled for all animals.

Pregnancy losses in Bos indicus-influenced beef and dairy recipients assigned to a fixed-time embryo transfer protocol

Pregnancy losses from fixed-time embryo transfer (FTET) to calving were evaluated in Bos indicus-influenced beef and dairy recipients. Data from 4366 FTET events were collected from Nelore × Angus recipient heifers, and from 38538 FTET events in Gir × Holstein recipient heifers and cows. In beef recipients, pregnancy losses were greater (P < 0.01) from FTET (day 7 of the experiment) to day 32 compared with day 32–100 and with day 100 to calving (58.7, 39.5, and 36.7%, respectively), and did not differ (P = 0.56) between these latter periods. Recipients that lost the pregnancy from FTET to day 32 gained less (P < 0.01) body condition score after FTET compared with recipients that maintained the pregnancy. Pregnancy losses from day 32 to calving were greater (P < 0.01) in recipients reared in drylots and moved to pastures on day 32 compared with recipients reared on pasture. In dairy recipients, pregnancy losses from FTET (day 7) to day 32 were greater (P < 0.01) than losses from day 32 to calving (50.4 and 29.4%). Pregnancy losses throughout gestation were greater (P < 0.01) when the FTET event was performed during the warm season, and greater (P < 0.01) in recipients with < 3/8 Gir influence. Recipients with ≥ 3/8 Gir influence experienced a lesser (P ≤ 0.05) increase in pregnancy losses during the warm season compared with recipients with < 3/8 Gir influence. Collectively, this experiment provides novel information about pregnancy losses in B. indicus-influenced herds receiving FTET.

Human proinsulin production in the milk of transgenic cattle.

The worldwide growing demand for human insulin for treating diabetes could be supplied by transgenic animals producing insulin in their milk. Pseudo-lentivirus containing the bovine β-casein promoter and human insulin sequences was used to produce modified adult fibroblasts, and the cells were used for nuclear transfer. Transgenic embryos were transferred to recipient cows, and one pregnancy was produced. Recombinant protein in milk was evaluated using western blotting and mass spectrometry. One transgenic cow was generated, and in milk analysis, two bands were observed in western blotting with a molecular mass corresponding to the proinsulin and insulin. The mass spectrometry analysis showed the presence of human insulin more than proinsulin in the milk, and it identified proteases in the transgenic milk that could convert proinsulin into insulin and insulin-degrading enzyme that could degrade the recombinant protein. The methodologies used for generating the transgenic cow allowed the detection of the production of recombinant protein in the milk at low relative expression compared to milk proteins, using mass spectrometry, which was efficient for detecting recombinant protein with low expression in milk. Milk proteases could act on protein processing converting recombinant protein to functional protein. On the other hand, some milk proteases could act in degrading the recombinant protein.

Effect of heatwaves on the pregnancy rate of dual-purpose recipient cows transferred with produced in-vitro embryos in tropical locations

Dual-purpose cows (n=648) from different genetic group (European, Zebu and crossbreeds cattle) were transferred with embryos produced in-vitro, in fresh or thawed, with the purpose of analyzing the effects of heatwaves on the pregnancy rate (PR) before, during, and after the transfer. The weather data used (temperature and humidity) were obtained on-site in production units to determine the temperature-humidity index (THI), and it was established that THI values of ≥74 before (-4, -3 and -2 days), during (-1, 0 and +1), and after (+2, +3 and +4) the transfer constitute a heatwave, with day “0” being the transfer day. The 2K contingency table was used, with a xi2 distribution and logistic regression (Statistica, v10), to find the PR in the recipient cows. The intrinsic variables considered were the corpus luteum size (CL1, CL2 and CL3), body condition, parity, and genetic group; while the extrinsic variables were the geographical area, embrionary development stage, embryo preservation method and quality. The presence of a heatwave before, during and after the transfer lowered the PR by 13% (p&lt; 0.05), with it being 43% in conditions of thermal comfort, and 30% during a heatwave, the odd ratio was 0.6404 - 0.4652. The PR was lower in the presence of a heatwave across the three genetic groups (30.09, 33.33 and 35.20% by Zebu, European, and crossbreeds cattle, respectively), as well as in cows with smaller CL (CL3, 29.38%). Body condition, parity and embrionary development stage were not associated with the heatwave (p&gt;0.05). Thawed embryos are more susceptible to heatwaves, their PR being lower (16.81%). It was concluded that the heatwave lowered the PR of the recipient cows by 13%.

Efeito do tratamento com gonadotrofina na transferência de embriões nos resultados de prenhez em bovinos

Abstract The objectives were to evaluate the effects of recipient category, season and administration of a gonadorelin analogue at the time of fixed-time embryo transfer (FTET) on pregnancy per FTET at 30 and 60 days after oestrus and on pregnancy losses (PL). Recipients were randomly assigned to: treated group (n = 624), in which recipients received an intramuscular injection of 0.2 mg of gonadorelin (Fertagyl®) at FTET; or a control group (n = 687) that remained untreated. Recipients were previously treated with a synchronisation protocol based on progesterone and oestradiol. All embryos were produced in vitro. The data with binomial distribution were analysed by multivariate logistic regression, using the GLIMIX procedure of SAS. Higher P/FTET was observed at 30 days (45.8 vs. 40.0%; P = 0.03) and 60 days (43.0 vs. 37.0%; P = 0.01) in the treated group. There was a tendency toward reduced PL in the treated group (4.0 vs. 7.0%; P = 0.09). Dry cows (2.70%) and lactating cows (2.47%) had less PL (P = 0.001) compared with heifers (10.42%). In the spring/summer season the P/ FTET at 60 days was smaller (P =0.024). Greater PL tended to occur in the warmer season. Treatment with gonadorelin at the time of bovine ET increased the pregnancy per ET at days 30 and 60 and reduced PL. Additionally, dry and lactating recipient cows showed a lower PL rate compared to heifers. Furthermore, ET performed in the warmer seasons of the year resulted in a lower pregnancy rate at day 60 and greater PL.

Concentration of progesterone in the blood serum and size of the corpus luteum as criteria for selection of recipient cows for embryo transfer

Pregnancy rate is the main factor influencing the productivity and economic efficiency of animal farming. Transfer of bovine cattle embryos is currently one of the most promising methods of overcoming the problem in the reproduction sphere. That is why the objective of our research was to identify progesterone concentration in blood serum and size of the corpus luteum in the cows on the day of embryo transfer in order to improve the strategy of selecting recipient animals, and, as a result, increase the conception rate. All animals admitted to the experiment were divided into three groups based on concentration of progesterone in the blood serum, being &lt;2.5 ng/cm3 in the first, 2.5 to 5.0 ng/cm3 in the second, and &gt;5 ng/cm3 in the third group. Progesterone concentrations in the blood serum and sizes of corpora lutea were determined on the day of embryo transfer (7th day after estrus). The animal was considered pregnant according to a positive result of ultrasound examination. Based on the study results, we concluded that measuring the progesterone content in the blood serum and the size of the corpus luteum are not interchangeable. We found that sizes of corpora lutea did not correlate with concentrations of progesterone in the blood serum of the experimental recipient cows. However, the size of the corpus luteum was of significant predictive value for pregnancy rate. We saw that decrease in its diameter below 15 mm, even against the background of high progesterone concentration, was a negative criterion for selection of the recipient animals. Optimal progesterone concentration in blood serum of the experimental animals was within 2.5–5.0 ng/cm3, leading to the highest pregnancy rate in the groups – 46.7. The hormone parameter outside the indicated range led to a significant decline in the pregnancy rate in the recipient animals. Therefore, when selecting recipient cows prior to transfer, both progesterone concentration in the blood serum and the diameter of the corpus luteum should be taken into account, which should not be beyond the proposed ranges. The data presented and analyzed in the article can help improve the efficiency of transfer of bovine cattle embryos for scientific and industrial purposes.

Fertility in seasonal-calving pasture-based lactating dairy cows following timed artificial insemination or timed embryo transfer with fresh or frozen in vitro–produced embryos

The objective was to compare pregnancy per service event (P/S) in lactating dairy cows following timed artificial insemination (AI) or timed embryo transfer (ET) using either fresh or frozen in vitro-produced embryos. Oocytes were collected once per week for up to 9 wk using transvaginal ovum pick-up from elite dairy donors (ET-DAIRY; n = 40; Holstein-Friesian and Jersey) and elite beef donors (ET-ELITE-BEEF; n = 21; Angus). Both ET-DAIRY and ET-ELITE-BEEF donors consisted of heifers and cows. In addition, oocytes were collected from the ovaries of beef heifers of known pedigree following slaughter at a commercial abattoir (ET-COMM-BEEF; n = 119). Following in vitro maturation and fertilization, presumptive zygotes were cultured in vitro to the blastocyst stage. Grade 1 blastocysts were either transferred fresh or frozen for on-farm thawing and direct transfer. A total of 1,106 recipient cows (all lactating, predominantly Holstein-Friesian) located on 16 herdlets were blocked based on parity, calving date, and Economic Breeding Index, and randomly assigned to receive AI (n = 243) or ET (n = 863) after estrous synchronization with a 10-d Progesterone-synch protocol. Cows assigned to ET were further randomized to receive fresh (n = 187) or frozen (n = 178) ET-ELITE-BEEF embryos, fresh (n = 169) or frozen (n = 162) ET-DAIRY embryos, or fresh (n = 80) or frozen (n = 87) ET-COMM-BEEF embryos. Pregnancy was diagnosed using transrectal ultrasound on d 32 to 35 after synchronized ovulation and confirmed on d 62 to 65, at which time fetal sex was determined. Pregnancy per service event at d 32 was not different between AI (48.8%) and ET (48.9%) and did not differ between dairy and beef embryos (50.3% vs. 48.1%, respectively). However, P/S was less on d 32 following transfer of frozen embryos (41.6%) compared with fresh embryos (56.1%). Pregnancy loss between d 32 and 62 was greater for ET (15.1%) compared with AI (4.7%), with greater losses observed for frozen beef (18.5%), fresh beef (17.3%), and frozen dairy (19.2%) compared with fresh dairy (6.0%) embryos. Serum progesterone (P4) concentration on d 7 was associated with P/S at d 32 and 62. Cows in the quartile with the least serum P4 concentrations (quartile 1) had less probability of being pregnant on d 32 (33.4%) compared with cows in the 3 upper quartiles for serum P4 (45.7%, 55.6%, and 61.2% for quartile 2, quartile 3, and quartile 4, respectively). Sex ratio (male:female) at d 62 was skewed toward more male fetuses following ET (61.1:38.9) compared with AI (43.2:56.8) and was consistent with the sex ratio among in vitro blastocysts (61.2:38.8). In conclusion, P/S was similar for AI and ET, although pregnancy loss between d 32 and 62 was greater for ET than for AI.

Sex ratio and conception rates of fresh/vitrified embryos at different developmental stages by ovum pick up in Hanwoo cows.

Embryo transfer plays a crucial role in enhancing the breeding value of livestock; it has been applied in Hanwoo cattle, which is a popular breed for beef production in Korea. Both in vivo-derived (IVD) and in vitro-produced (IVP) embryos are used for this purpose; however, IVP embryos have been preferred recently owing to advancements in ovum pick-up (OPU) technology and genomic selection. Despite technological advancements, comprehensive data on large-scale OPU/IVEP/embryo transfer in Hanwoo cows are lacking. In this study, 16 elite Hanwoo donor cows were selected on the basis of specific criteria. Oocytes were retrieved from 241 cows using OPU. The collected cumulus-oocyte complexes (COCs) were matured, fertilized, and cultured in vitro to produce transferable embryos. Embryos were classified according to their developmental stage and then transferred to 675 recipient cows. A total of 3,317 COCs were collected, with an average of 13.76 COCs per cow. The number of transferable embryos produced per cow was 3.7. Hanwoo OPU-derived IVP embryos exhibited a higher production yield than the global average, indicating a stable IVEP environment. Both fresh and frozen IVP embryos yielded similar conception rates; hence, the use of vitrified-thawed embryos in transfer plans feasible. However, frozen-thawed embryos at Stage 7 had a lower conception rate than those at earlier stages. There was no significant difference between the conception rates of sexually mature heifers and postpartum cows used as recipients. The male-to-female offspring ratio increased as the developmental stage progressed. Seasonal effects on conception rates were not observed; however, higher abortion rates and a higher proportion of male offspring were observed during winter. This study provides valuable data for the Korean embryo transfer industry, enabling more strategic growth of the domestic Hanwoo embryo industry.

Production of Somatic Cell Nuclear Transfer derived cloned calves in the United Arab Emirates.

Despite the tremendous advancement in somatic cell nuclear transfer (SCNT) in camels, the generation of cloned calf using SCNT in cows is yet to be reported in the United Arab Emirates (UAE). The present study intended to produce cloned calves in the local environment of the UAE. We surgically collected ear tissue from two high-performance Holstein cows (average production of 71 liter/ day) and established the fibroblast cell line to perform SCNT. Fifty- seven (18.48%) blastocysts were derived from 330 fused oocytes for cell donor A, and 51 (19.14%) blastocysts were generated from 289 fused oocytes for cell donor B. We used 102 recipients for embryo transfer; among those, 53 and 49 recipients received embryos reconstructed with cell donor A and B, respectively. A single blastocyst in transfer media was transferred deep into the horn of the uterus of natural cycling recipient cows by trans cervical method on Day 7; where estrus was considered as Day 0. Non-return to estrus (up to 42 days), early pregnancy, and the live birth rate did not differ significantly for the two donor cells. Four (26.67%) and 1 (7.69%) live calves were produced for cell donor A and B, respectively. Microsatellite analysis of 18 bovine-specific loci confirmed the perfect match of cell donors and cloned calves. This is the first reported case of cloned calves using SCNT in the UAE. Our results could benefit the UAE dairy industry by supporting the locally produced high- performance replacement heifers. Keywords: Bovine; Cloning; In vitro maturation; Oocytes; UAE

55 Investigating the Potential Benefits of an Immunostimulant (Mycobacterium Cell Wall Fraction) Treatment on Increased Pregnancy Success of Embryo Transfer Recipients

Abstract Modulating the vaginal and uterine microbiome through the use of immunostimulants has the potential to improve fertility in cattle. The object of this study was to evaluate the potential benefits of an immunostimulant, mycobacterium cell wall fraction (MCWF), to increase pregnancy success of embryo transfer (ET) recipients. The three main objectives of this study were: determining if injecting ET recipient cows with MCWF increased proportion of cows with a corpus luteum (CL) on ET day, identifying differences in CL volume and progesterone concentration at the time of ET, and determining if ET recipients that received MCWF have greater pregnancy rate. A total of 926 beef cows at eight different locations were enrolled in this study. Primiparous and multiparous cattle were enrolled in a 7-day CO-Synch + CIDR estrous synchronization protocol. During this protocol, cows received an injection of GnRH (100-μg) at CIDR (controlled internal drug release) insertion [d -9], a prostaglandin F2α injection (25 mg), and CIDR removal [d-2] followed by another injection of GnRH (100 μg; d 0) within 60-66 hours after CIDR removal. At each location at (d 0), cows were sorted based on BCS and days post-partum and randomly assigned to one of two treatments: 1) MCWF- a single intramuscular injection (5 mL) of MCWF at (d 0; Amplimune, NovaVive Inc.; n = 452) or 2) Control- a single intramuscular injection (5 mL) of saline (n = 474). Seven days after (d 7), cows were examined by ultrasonography to determine if a CL was present. Recipient cows that had a CL received ET with a frozen or fresh in vivo or in vitro produced embryo in the ipsilateral uterine horn to the CL, with embryo type and grade balanced between treatments. Blood samples were collected in one location (n = 98) for analysis of plasma concentration of progesterone on (d 7) ET day. Pregnancy diagnosis was then performed by ultrasonography between 30 and 90 days of gestation. Data were analyzed using the GLIMMIX and MIXED procedures of SAS. Cow BCS and days postpartum were similar (P &amp;gt; 0.10) between treatments (5.5 ± 0.6 and 103 ± 14 days, respectively). Recipient cow utilization rate was similar between treatments (P = 0.49; 81.2 ± 0.42%). At the time of ET MCWF had larger CL than Control cows (5,768.6 ± 133.7 and 5,408.0 ± 128.5 mm3, respectively, P = 0.03). and increased progesterone concentration (2.68 ± 0.17 and 2.18 ± 0.14 ng/mL, respectively, P = 0.01). However, pregnancy rate to ET was similar (P = 0.922) between treatments (60.9 and 61.3 ± 0.05% for Control and MCWF, respectively). In conclusion, treatment of ET recipient cows with MCWF increased CL volume and concentration of progesterone at the time of ET but failed to generate greater pregnancy rates.

Bovine blastocyst-like structures derived from stem cell cultures

Understanding the mechanisms of blastocyst formation and implantation is critical for improving farm animal reproduction but is hampered by a limited supply of embryos. Here, we developed an efficient method to generate bovine blastocyst-like structures (termed blastoids) via assembling bovine trophoblast stem cells and expanded potential stem cells. Bovine blastoids resemble blastocysts in morphology, cell composition, single-cell transcriptomes, invitro growth, and the ability to elicit maternal recognition of pregnancy following transfer to recipient cows. Bovine blastoids represent an accessible invitro model for studying embryogenesis and improving reproductive efficiency in livestock species.

Impact of Accessory Corpus Luteum Induced by Gonadotropin-Releasing Hormone or Human Chorionic Gonadotropin on Pregnancy Rates of Dairy Cattle following Embryo Transfer: A META-Analysis.

The circulation of progesterone (P4) concentrations of recipients has positive correlations with embryo survival and pregnancy success of embryo transfer (ET) in dairy cows. One strategy to improve P4 concentration is the administration of gonadotropin-releasing hormone (GnRH) or human chorionic gonadotropin (hCG), thereby inducing the formation of accessory corpus luteum (CL). This study aimed at determining the efficacy of GnRH or hCG treatment regarding embryo transfer (ET) and providing a better clinical veterinary practice guidance. A meta-analysis was conducted on the data from 2048 treated recipient cows and 1546 untreated cows. By inducing the formation of accessory CL with GnRH (100 µg), GnRH analogue Buserelin (8-10 µg), or hCG (≥1500 IU) 5-11 days after synchronized ovulation, hCG alone achieved an improvement (RR = 1.39, p < 0.05), while GnRH and GnRH analogue did not result in significant changes (RR = 1.04, p = 0.26). Treatment with GnRH or hCG 5-7 days after synchronized ovulation was associated with increased chances of pregnancy compared with later treatment (11-14 days). Owing to the treatment, the pregnancy rate of cows with very poor fertility (<40%) was improved, while that of cows with good fertility (≥40%) was not affected. Treatment with GnRH or hCG greatly improved pregnancy rates of parous lactating cows (RR = 1.32, p < 0.05) compared with heifers (RR = 1.02, p > 0.05). Additionally, as indicated by pregnancy loss analysis, the treatment had no benefit on late embryo/early fetus survival at days 28-81. In conclusion, the induction of accessory CL with GnRH or hCG may benefit fertility and have important implications for the management of reproductive performance in the dairy industry.

Effects of abomasally infused rumen fluid from corn-challenged donor cows on production, metabolism, and inflammatory biomarkers in healthy recipient cows

Subacute rumen acidosis may cause postruminal intestinal barrier dysfunction, but this does not appear to be due to increased hindgut fermentation. Alternatively, intestinal hyperpermeability may be explained by the plethora of potentially harmful substances (e.g., ethanol, endotoxin, and amines) produced in the rumen during subacute rumen acidosis, which are difficult to isolate in traditional in vivo experiments. Therefore, objectives were to evaluate whether abomasal infusion of acidotic rumen fluid collected from donor (Donor) cows elicits systemic inflammation or alters metabolism or production in healthy recipients. Ten rumen-cannulated lactating dairy cows [249 ± 63 d in milk; 753 ± 32 kg of body weight (BW)] were randomly assigned to 1 of 2 abomasal infusion treatments: (1) healthy rumen fluid (HF; 5 L/h; n = 5) or (2) acidotic rumen fluid (AF; 5 L/h; n = 5) infused. Eight rumen-cannulated cows [4 dry, 4 lactating (lactating = 391 ± 220 d in milk); 760 ± 70 kg of BW] were used as Donor cows. All 18 cows were acclimated to a high-fiber diet (46% neutral detergent fiber; 14% starch) during an 11-d prefeeding period during which rumen fluid was collected for the eventual infusion into HF cows. During period (P) 1 (5 d), baseline data were obtained and on d 5 Donor were corn-challenged (2.75% BW ground corn after 16 h of 75% feed restriction). Cows were fasted until 36 h relative to rumen acidosis induction (RAI), and data were collected through 96 h RAI. At 12 h RAI, an additional 0.50% BW of ground corn was added, and acidotic fluid collections began (7 L/Donor every 2 h; 6 M HCl was added to collected fluid until pH was between 5.0 and 5.2). On d 1 of P2 (4 d), HF/AF cows were abomasally infused with their respective treatments for 16 h, and data were collected for 96 h relative to the first infusion. Data were analyzed in SAS (SAS Institute Inc.) using PROC MIXED. Following the corn challenge in the Donor cows, rumen pH only mildly decreased at nadir (pH = 5.64 at 8 h RAI) and remained above the desired threshold for both acute (5.2) and subacute (5.6) acidosis. In contrast, fecal and blood pH markedly decreased to acidotic levels (nadir = 4.65 and 7.28 at 36 and 30 h RAI, respectively), and fecal pH remained below 5 from 22 to 36 h RAI. In Donor cows, dry matter intake remained decreased through d 4 (36% relative to baseline) and serum amyloid A and lipopolysaccharide-binding protein markedly increased by 48 h RAI in Donor cows (30- and 3-fold, respectively). In cows that received the abomasal infusions, fecal pH decreased in AF from 6 to 12 h relative to the first infusion (7.07 vs. 6.33) compared with HF; however, milk yield, dry matter intake, energy-corrected milk, rectal temperature, serum amyloid A, and lipopolysaccharide-binding protein were unaffected. Overall, the corn challenge did not cause subacute rumen acidosis but markedly decreased fecal and blood pH and stimulated a delayed inflammatory response in the Donor cows. Abomasal infusion of rumen fluid from corn-challenged Donor cows decreased fecal pH but did not cause inflammation, nor did it create an immune-activated phenotype in recipient cows.

Histological Characteristics of the Endometrium and its Affecting Factors in Dairy Cattle (Bos taurus) on Embryo Transfer Day

Abstract In cows embryo transfer occurs on the 7th day of the oestrous cycle. Embryo survival and successful pregnancy depend on many factors, including early interaction between embryo and endometrium. Therefore, the aim of our research was to describe histo-morphological characteristics of endometrium in donor and recipient cows on obtaining and transfer day, respectively (7th day of the oestrus cycle). In addition, progesterone and oestradiol levels, the ipsilateral and contralateral corpus luteum, animal age, lactation number and days postpartum were determined. The results of the study revealed a significant difference in endometrial gland cell size, vacuolisation of glandular epithelium cytoplasm, and stromal oedema in the donor and recipient cows. However, these parameters were related only to the level of progesterone in the blood, and no other investigated factors in this study.

Effect of Selected Micro- and Macroelements and Vitamins on the Genome Stability of Bovine Embryo Transfer Recipients following In Vitro Fertilization

Genome instability can lead to a wide variety of diseases. Many endogenous and exogenous factors influence the level of damage to genetic material. Genome integrity depends on factors such as the fidelity of DNA replication, normal DNA organization in the chromosomes, and repair mechanisms. Genome stability influences fertility, embryonic development, and the maintenance of pregnancy. In the case of in vitro fertilization, it can be an important factor determining the success of the procedure. The aim of the study was to assess the stability of the genomes of recipient cows following in vitro fertilization using cytogenetic tests and to analyze the effects of selected vitamins and micro- and macroelements on genome integrity. Genome stability was analyzed using the sister chromatid exchange, fragile site, and comet assays. The material for analysis was peripheral blood from 20 Holstein-Friesian heifers that were embryo transfer recipients. The effect of selected micro- and macroelements and vitamins on the genome stability of the cows was analyzed. Folic acid was shown to significantly influence the level of damage identified using the SCE, FS, and SCGE assays, while iron affected SCE and SCGE results, and zinc affected FS.

Transmission of Mycoplasma bovis infection in bovine in vitro embryo production

Mycoplasma bovis (M. bovis) causes several costly diseases in cattle and has a negative effect on cattle welfare. There is no effective commercial vaccine, and antimicrobial resistance is common. Maintaining a closed herd is the best method to minimize the risk of introduction of M. bovis. Assisted reproduction is crucial in a closed herd to make genetic improvements. M. bovis has been found in commercial semen, and contaminated semen has been the source of disease in naïve dairy herds. The objective of this study was to evaluate M. bovis transmission in bovine in vitro embryo production (IVP) using several possible exposure routes. We used a wild-type M. bovis strain isolated from semen at a final concentration of 106 CFU/mL to infect cumulus–oocyte complexes, spermatozoa, and 5-day-old embryos. We also used naturally contaminated semen in fertilization. Blastocysts were collected on day 7–8 and zona pellucida (ZP)-intact embryos were either washed 12 times, including trypsin washes as recommended by the International Embryo Technology Society (IETS), or left unwashed. Washed and unwashed embryos, follicular fluids, maturation medium, cumulus cells, fertilization medium, and G1 and G2 culture media, as well as all wash media were analyzed using enrichment culture followed by real-time PCR detection of M. bovis. Altogether, 76 pools containing 363 unwashed embryos and 52 pools containing 261 IETS washed embryos were analyzed after oocytes, spermatozoa, or 5-day-old embryos were infected with M. bovis or naturally contaminated semen was used in fertilization. We could not detect M. bovis in any of the embryo pools. M. bovis was not found in any of 12 wash media from different exposure experiments. M. bovis did not affect the blastocyst rate, except when using experimentally infected semen. Contrary to an earlier study, which used a cell co-culture system, we could not demonstrate M. bovis in embryo wash media or tight adherence of M. bovis to ZP-intact embryos. Naturally infected semen did not transmit M. bovis to embryos. We conclude that by using our IVP system, the risk of M. bovis transmission via IVP embryos to recipient cows is very low.

Bioclimatic interference in fertility in cows in the Amazon biome

The objective was to evaluate the correlation between environmental temperature-humidity index (THI), rectal temperature (RT), plasma cortisol concentration and pregnancy rate in embryo recipient cows in the Amazon biome. Embryo recipients (n=235) underwent estrus synchronization via simplification of the P36 protocol for Fixed-Time Embryo Transfer (TETF). On days zero (D0), eight (D8) and day 16 (D16), the rectal temperature of the recipient cows was measured, as well as the ambient temperature and relative humidity. On the 16th day after the start of the synchronization protocol (D16), each recipient received an embryo transferred after being diagnosed with a corpus luteum (CL) in one of the ovaries by ultrasonography (US) and, from each of them, a blood sample was collected by venipuncture of the coccygeal vein, in tubes with ethylenediaminetetraacetic acid (EDTA) as an anticoagulant to obtain blood plasma, where cortisol was measured by radioimmunoassay (RIA) in solid phase, using commercial kits. It was found that in the group of pregnant cows, the mean values of the parameters RT, plasma cortisol and THI (P &lt; 0.05) were lower than those presented in the group of non-pregnant cows. Moreover, between the two groups there were positive and significant correlations between RT and THI (P &lt; 0.05), as well as in relation to plasma cortisol parameters and THI (P &lt; 0.05). It is concluded that it is possible to validate the use of RT and THI as an auxiliary tool for estimating plasma cortisol concentrations.