[Importance of reproductive biotechnology in cattle in Europe]

Reproductive biotechnology has manifold applications and includes a great innovation potential in livestock. Due to the global changes the new findings and techniques can aid to meet the future challenges. The use of biotechnology in animal production can guarantee enough high quality food for the whole population. Genetic resources of animals can be preserved via sperm and embryo banking. Early diagnosis of hereditary defects, generation of offspring with predetermined sex and the avoidance of animal transports for breeding employing shipment of frozen embryos will improve animal welfare. A special application is the use of animal models for human assisted reproductive technologies. Therefore, not only in Germany research related to the methodologies in reproductive biotechnology and their improvement need to be supported.

200 STAGE-SPECIFIC EXPRESSION PATTERNS OF THE INSULIN-LIKE GROWTH FACTOR 1 RECEPTOR DURING BOVINE PRE-IMPLANTATION EMBRYONIC DEVELOPMENT

Insulin-like growth factor 1 (IGF1) is a key regulator in early embryonic development, influencing physiological processes and stimulating growth and development (Fowden et al. 2003). Supplementing IGF1 during in vitro culture of bovine embryos improved cleavage and developmental rates while it reduced apoptosis (Byrne et al. 2002). The signal transduction of IGF1 is performed by its binding to the insulin-like growth factor 1 receptor (IGF1R). At the mRNA level, IGF1R is expressed throughout pre-implantation embryonic development and was identified as a potential marker of good quality embryos (Yaseen et al. 2001). However, information on protein level is rare. Therefore, protein expression of the IGF1R during early embryonic development in vitro was analysed in the present study by immunofluorescence staining. Furthermore, the mRNA expression of the IGF1R was investigated by RT-qPCR. In vitro derived embryos of different stages (2-cell, 4-cell, 8-cell, 16-cell stage, morula, blastocyst, and expanded blastocyst) were either directly subjected to immunofluorescence staining or frozen at –80°C for use in RT-qPCR. Staining was performed with a peptide antibody against two peptide sequences of the bovine IGF1R α unit, which was specifically produced. Pixel intensity of immunofluorescence was measured and a mean grey value was calculated using the cellsens® software (Olympus, Hamburg, Germany). Data were analysed by one-way ANOVA followed by a Tukey's test using SigmaStat 3.5 Software (Systat Software GmbH, Erkrath, Germany). The detection of the IGF1R mRNA and protein was possible in all stages of embryonic development beginning at the 2-cell stage up to the expanded blastocyst. The maximal mRNA expression could be observed in 2- and 4-cell embryos. It significantly decreased to the 8-cell stage, followed by an increase up to the expanded blastocyst. The IGF1R protein was mainly localised in the plasma membrane of single blastomeres and also weakly in the cytoplasm. Mean grey values are highest in the 2-cell stage, showing a significant decline up to the 16-cell stage and an increase again until the expanded blastocyst. The mRNA and protein expression showed similar patterns during early embryonic development. IGF1R expression started to increase at the 8-cell stage (mRNA) and 16-cell stage (protein) indicating a link to the maternal-embryonic transition. For the first time, these results show that in bovine embryos, the IGF1R expression is related to the activation of the embryonic genome. We gratefully acknowledge the financial support of the H. Wilhelm Schaumann Foundation (Hamburg, Germany).

275 TEMPORAL PATTERN OF STEROID HORMONE CONCENTRATIONS DURING IN VIVO AND IN VITRO MATURATION OF BOVINE OOCYTES

Steroid hormone concentration and property can be modulated via different processes. Sulfoconjugation via sulfotransferases (SULT) changes steroids from hydrophobic to hydrophilic, necessitating a transport system such as the sodium-dependent organic anion transporter (SOAT; SLC10A6). Steroid sulfatase (STS) removes the sulfate moiety from conjugated steroids, transforming them to the free active ones. Moreover, present in vitro maturation systems do not completely mimic the in vivo situation resulting in oocytes of reduced quality. The present study investigates the local effects of sulfated steroids during follicular and oocyte development in vivo and in vitro. Follicles of bovine abattoir-derived ovaries were categorized according to their size (3 to 5, 6 to 8, 9 to 14, and >15 mm) after dissection and measurement via a caliper. Only nonatretic follicles were used (Kruip and Dieleman, 1982). Follicular fluid was collected via aspiration and analysed for the presence of steroids and their sulfated counterparts via LC-MS/MS. Moreover, oocytes were in vitro maturated with a standard protocol. The medium was measured via radioimmunoassay after 0, 4, 8, 12, 16, 20, and 24 h to detect 17β-oestradiol (E2) and progesterone (P4). Data were tested using analysis of variance (ANOVA) followed by multiple pairwise comparisons using Tukey's test. A P-value of ≤0.05 was considered significant. It was possible to detect 17β-oestradiol, progesterone, testosterone, 17β-oestradiol sulfate, estrone sulfate, pregnenolone sulfate, cholesterol sulfate (Table 1), and furthermore androstendione, estrone, androsterone, and 17OH-pregnenolone. During IVM, P4 significantly increased in the medium (4 h: 3.3 ± 1.0 ng mL–1; 24 h: 9.8 ± 1.7 ng mL–1), whereas the E2 concentration did not change (4 h: 52.8 ± 12.1 pg mL–1; 12 h: 68.4 ± 3.7 pg mL–1; 24 h: 66.9 ± 19.7 pg mL–1). In addition, preliminary data suggest that transcripts of the steroid metabolizing and transporting enzymes (SULT1E1, STS, SLC10A6) were present in cumulus cells from immature bovine COC. These results indicate for the first time that only small amounts of sulfated steroids are present in bovine follicular fluid. However, the related enzymes are present at the mRNA level. Further studies are underway to analyse the protein level. Table 1.Steroid hormone concentration in follicular fluid We thank Prof. Dr Wudy and A. Sánchez Guijo for the LC-MS/MS analysis. Furthermore, we gratefully acknowledge the financial support of the German Research Foundation (DFG; FOR 1369).

70 PROTEIN EXPRESSION OF THE INSULIN-LIKE GROWTH FACTOR 1 RECEPTOR DURING BOVINE PRE-IMPLANTATION EMBRYONIC DEVELOPMENT

Insulin-like growth factor 1 (IGF1) is essential for regulating physiological processes such as growth and development of fetal and placental tissues (Bauer et al. 1998, Fowden 2003). During early embryonic development, IGF1 plays an important role, as it leads to a reduction of apoptosis and decreases early embryonic mortality (Block et al. 2007). The signal transduction of IGF1 is carried out by its specific binding to the membrane-embedded insulin-like growth factor 1 receptor (IGF1R). The expression of IGF1R is a potential quality marker of in vitro produced embryos (Liu et al. 1997, Yaseen et al. 2001). Thus far, analysis of the relative amount of specific transcripts is the method of choice to study bovine pre-implantation embryos, as information on protein expression is scarce. Therefore, it is of great interest to analyse protein expression and to determine if and to which extent these results differ from results obtained in previous mRNA expression analyses. In the present study, a total of 4800 cumulus-oocyte-complexes were deployed in 60 in vitro produced runs. The cleavage rates averaged 57.4 ± 7.3% and blastocyst rates were 27.6 ± 7.5% at Day 8 of culture. Embryos at the blastocyst stage were frozen and stored at –80°C for further experiments. The protein expression of the IGF1R during early embryonic development was investigated by Western blot analysis testing 8 different antibodies. Seven of these antibodies were commercially available and mainly not tested in the bovine species. Only 1 of these antibodies resulted in a weak signal for the IGF1R protein in bovine blastocysts. Therefore, a specific peptide antibody against 2 peptide sequences of the α unit of the bovine IGF1R was produced. The analysis of the IGF1R protein with this antibody resulted in the determination of a signal in a pool of 100 blastocysts, which was weaker than in the positive control (20 μg of bovine liver protein extract). The detection of the IGF1R protein localization was possible in all different stages of embryonic development from the zygote to the expanded blastocyst using immunfluorescence staining with the specific peptide antibody. The IGF1R protein was mainly expressed in the plasma membrane of single blastomeres and also weakly in the cytoplasm. As the early bovine embryo expresses IGF1R throughout all stages, the main function of IGF1 in embryonic development needs to be further elucidated. We gratefully acknowledge the financial support of the H. Wilhelm Schaumann Foundation (Hamburg, Germany).

71 EFFECTS OF A CONTROLLED DIETARY EXPOSITION TO ZERALENONE ON SELECTED REPRODUCTIVE PARAMETERS IN DAIRY COWS

Whole plant corn silage is an important component of dairy cow nutrition. Growing conditions in a moderate climate, as are present in large parts of Europe and North America, are often beneficial for mould contaminations to occur. Very commonly, varieties of Fusarium spp. grow on the corn plant producing the non-steroidal estrogenic mycotoxin zearalenone (ZEN). Numerous studies have shown that ZEN massively interacts with the porcine reproductive system. Nevertheless, only a few studies have assessed the possible effects on dairy cows, most publications being field studies following accidental exposure. Therefore, it was aim of the present study to assess the effects of a controlled dietary exposition on selected reproductive parameters in dairy cows. The chosen exposure concentration was within the range of the ‘Commision Recommendation on the presence of deoxynivalenol, zearalenone, ochratoxin A, T-2 and HT-2 and fumonisins in products intended for animal feeding’ of the European Union. Corn plants were artificially inoculated with Fusarium spp. and the silage obtained from the whole plant was analysed to determine to which degree the silage contained ZEN. Thirty Holstein Friesian cows and heifers (aged between 2 years 3 months and 5 years at calving) were allocated to 3 groups with 10 animals each: control (CTL), uncontaminated silage; ZEN 50, silage with 0.25 mg of ZEN/day; and ZEN 100, silage with 0.5 mg of ZEN/day. The contaminated rations were distributed by automated feeding stations to ensure an equal uptake. Feeding began 7 days post-parturition. Blood samples were obtained twice weekly for 12 weeks and were analyzed regarding the progesterone level via radioimmunoassay. At the same time, the oestrous cycle was monitored by ultrasonography. Furthermore, the size of the corpus luteum (CL) was measured 7 ± 2 days after the third ovulation. Simultaneously, the luteal blood flow was documented via Doppler ultrasonography. The peripheral blood progesterone level (xgeom. ± CV; CTL: 9.3 ± 1.7; ZEN 50: 8.5 ± 1.6; ZEN100: 7.1 ± 1.5) did not differ among groups. Furthermore, it was not possible to detect differences in luteal blood flow, size of the CL (mean ± SD; CTL: 6.4 ± 1.7 cm2; ZEN50: 5.9 ± 1.3 cm2; ZEN 100: 5.0 ± 1.0 cm2) or the ratio of luteal size and size of the area supplied with blood (CTL: 0.1 ± 0.1; ZEN 50: 0.1 ± 0.0; ZEN 100: 0.1 ± 0.1). Although the mean length of the oestrous cycles (n = 60; distributed among groups) did not differ among groups (CTL: 24.0 ± 1.7 days; ZEN 50: 27.2 ± 1.6 days; ZEN 100: 27.7 ± 1.4 days), it was possible to detect an interaction between the age of the animal and the treatment regarding the cycle length in tendency (P < 0.07) by two-way ANOVA. The results of the present study indicate that, independent of the age of the animal, exposure to ZEN even within recommended dosages might result in an endocrine disruption in dairy cows. A larger sample size would contribute to the verification of these findings. Further analyses regarding the peripheral level of 17β-estradiol as well as molecular examinations are under progress.

114 PROGESTERONE CONCENTRATIONS DURING IVM AFFECT BOVINE OOCYTE QUALITY AT THE MOLECULAR LEVEL

Progesterone (P4) is important for the developmental competence of cumulus–oocyte complexes (COC) used for in vitro maturation (IVM). In a recent study, we were able to show that circulating P4 concentrations had an effect on the molecular quality of COC recovered during repeated ovum pickup sessions, which might affect further development. (Schlüter et al. 2013 Reprod. Fertil. Dev. 25, 250). The aim of the present study was to determine the influence of different P4 concentrations during IVM on the molecular quality of bovine COC. The COC were collected from slaughterhouse ovaries and cultured as described recently (Stinshoff et al. 2011 Theriogenology 76, 1433–1441). The IVM medium was supplemented with 0, 50, 150, 300, and 450 ng mL–1 P4. Ethanol served as vehicle control. After IVF with a bull of proven fertility, the presumptive zygotes were cultured in SOF under 5% oxygen (Stinshoff et al. 2011). Cleavage and developmental rates were determined at Day 3 and Day 7/8 (Day 0: IVF). Additionally, maturation rates were assessed. For mRNA analysis, immature and matured denuded COC (n = 5) were individually frozen at –80°C to analyse the relative transcript abundance using RT-qPCR. The transcripts studied play important roles during oocyte development [growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15), glucose transporter 1 (SCL2A1), hypoxia inducible factor 2α (HIF2α), nuclear progesterone receptor (PGR), progestin and adipoQ receptor 5 (PAQR5), progesterone receptor membrane component 1 and 2 (PGRMC1, PGRMC2)]. Data were tested using ANOVA followed by multiple pairwise comparisons using Tukey's test. A P-value of <0.05 was considered significant. The percentage of oocytes that reached the MII stage was similar in oocytes from all treatment groups (82.2–88.1%). Despite similar cleavage rates across all groups, the developmental rates did show significant differences. More embryos developed to the blastocyst stage stemming from oocytes cultured without any supplement or cultured only with alcohol compared to oocytes stemming from the group cultured with less than 50 ng mL–1 P4 (25.4 ± 5.7 and 27.9 ± 7.2 v. 15.8 ± 2.6). The relative abundance of SCL2A1, BMP15, and PGRMC1transcripts in single oocytes did not show differences related to the supplementation of the IVM medium, whereas GDF9, HIF2α, and PAQR5 mRNA was reduced in oocytes of all groups compared with immature ones. The PGR and PGRMC2 transcripts were increased in matured oocytes of the control group and the vehicle control group (PGRMC2). In summary, supplementation of the IVM medium with different P4 concentrations had an effect on the molecular quality of oocytes after IVM, which might affect further development. The financial support of the FBF (Förderverein Biotechnologieforschung) e.V. is gratefully acknowledged.

204 PERIPHERAL PROGESTERONE CONCENTRATION AFFECTS BOVINE OOCYTE QUALITY AT THE MOLECULAR LEVEL

The developmental competence of cumulus–oocyte complexes (COC) used for in vitro production is dependent on several factors including the stage of the oestrus cycle. In a recent study, we were able to show that circulating progesterone (P4) had no effect on follicle number, size, recovery rate, or in vitro production suitability of recovered COC (Schlüter et al. 2012 Reprod. Fertil. Dev. 24, 175–176). The aim of the present study was to determine the influence of circulating P4 concentrations on the molecular quality of bovine COC collected during repeated OPU sessions. The COC were aspirated twice per week for 5 to 6 weeks from 12 Holstein Friesian heifers. The first OPU session took place on Day 7 of the oestrous cycle after spontaneous ovulation (ovulation = Day 0). Blood samples were taken at the time of each OPU session, and P4 concentrations were determined using a radioimmunoassay. All animals showed clinical signs of oestrus and large follicles (≥8.5 mm) during the course of the OPU sessions. Following the aspiration of a large follicle, a CL-like structure (induced CL) could be detected. According to the P4 concentrations, the cycle was divided into 3 phases: CL phase after spontaneous ovulation (oCL; P4: ≥1 ng mL–1), follicle phase 1 (Fp; P4 <1 ng mL–1), and induced CL phase (iCL; P4: ≥1 ng mL–1). The length of the cycle after spontaneous ovulation did not differ significantly from that after induced ovulation (22.4 ± 3.1 days v. 23.8 ± 1.8 days, respectively). During the oCL-phase, blood P4 concentrations were significantly higher than during the iCL-phase (4.9 ± 2.3 ng mL–1 v. 3.0 ± 1.6 ng mL–1). For mRNA analysis, denuded COC were individually frozen at –80°C to analyse the relative transcript abundance using RT-qPCR. The transcripts studied play important roles during oocyte development [growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15), glucose transporter 1 (SCL2A1), hypoxia inducible factor 2α (HIF2α), progesterone receptor (PGR), progestin and adipoQ receptor 5 (PAQR5), progesterone receptor membrane component 1 and 2 (PGRMC1, PGRMC2)]. Data were tested using analysis of variance (ANOVA) followed by multiple pairwise comparisons using Tukey’s test. A P-value of ≤0.05 was considered significant. The relative abundance of all transcripts except SCL2A1 was significantly increased in oocytes collected from follicles of the oCL phase compared with that from oocytes that had been aspirated during the iCL phase. A significant increase in the relative amount of PGR, PGRMC1, PGRMC2, and BMP15 transcripts was detected in oocytes stemming from the follicular phase to those from the iCL phase. No differences in the relative abundance of all transcripts were seen comparing oocytes from oCL phase and oocytes from the follicular phase. In summary, circulating P4 concentrations had an effect on the molecular quality of COC recovered during repeated OPU session, which might affect further development. The financial support of the FBF (Förderverein Biotechnologieforschung) e.V. is gratefully acknowledged.

235 PROGESTERONE AFFECTS THE MESSENGER RNA EXPRESSION OF IN VITRO-PRODUCED BOVINE EMBRYOS

It is known that the progesterone (P4) provided by the corpus luteum is essential for the maintenance of pregnancy. It has been suggested that supplying external P4 in vivo is beneficial to the establishment and upkeep of pregnancy. The aim of the present study was to assess the effects of supplementation with different concentrations of P4 on either of 2 days of in vitro culture (IVC) on early bovine embryo development in an in vitro model. A total of 5073 cumulus–oocyte complexes were matured and fertilized in vitro. Before culture, they were collected in groups of 30 and allocated to 1 of 9 groups. The groups were supplemented with 10, 20, or 100 ng of P4 on Days 4 or 5 of IVC (IVF = Day 0). Alcohol (ETOH) was used as the solvent, so 8 µL of ETOH was used per supplementation. Therefore, two additional groups were supplemented with only ETOH on Day 4 or 5 of IVC. The presumptive zygotes allocated to group 9 were not supplemented. A culture system without oil overlay was used to prevent the lipophilic P4 from moving into the oil. Embryo cleavage and development rates were determined solely on Day 8 of IVC. Single expanded blastocysts were stored at –80°C for RT-qPCR. Subsequently, the relative amounts of six developmentally important gene transcripts (IGF1R, SLC2A1, HSD3B1, IFNT, PGRMC1, and PGRMC2) were analysed in single embryos of all groups. Statistical analysis was performed using one-way and two-way ANOVA, and the level of significance was set at P ≤ 0.05. Cleavage and development rates did not differ among groups (see Table 1). The relative abundance of IGF1R, SLC2A1, PGRMC1, and PGRMC2 was not affected by either the concentration or the timing of P4 supplementation. Nevertheless, there was a statistically significant interaction between the day of treatment and the concentration used for the expression of HSD3B1 mRNA. When 20 ng of P4 was added on Day 5 of IVC, significantly more HSD3B1 transcripts were detected than if 10 ng, 100 ng, or ETOH alone was added. The expression of IFNT was not affected by the day of supplementation, only by the concentration used. Thus, supplementation with 20 ng of P4 resulted in a significantly higher level of transcripts than when 10 ng or ETOH was supplemented. The results indicate that the amount of P4 present during early embryonic development and the timing of its presence had an impact on molecular developmental competence. However, no effects concerning morphological development up to the blastocyst stage could be detected. Table 1.Cleavage and development rates (± SEM) of embryos supplemented with 10, 20, or 100 ng on Day 4 or 5 of in vitro culture (P ≥ 0.05) The financial support of the FBF e.V. is acknowledged.

126 INFLUENCE OF PERIPHERAL PROGESTERONE CONCENTRATION ON MORPHOLOGICAL OOCYTE QUALITY IN REPEATED OVUM PICKUP SESSIONS

Today, ovum pickup (OPU) followed by in vitro production (IVP) of bovine embryos is an integral part of many breeding programs. The quality of the obtained cumulus–oocyte complexes (COC) limits the success of embryo production. The developmental competence of the COC is dependent on several factors, including the stage of the oestrous cycle, the stage of follicular development and the follicular diameter. The aim of the present study was to determine the influence of circulating progesterone (P4) concentrations during repeated OPU sessions on the morphological quality of bovine COC. Cumulus–oocyte complexes were aspirated twice weekly for 5 to 6 weeks from 12 Holstein Friesian heifers. The first OPU session took place on Day 7 of the oestrous cycle (ovulation = Day 0). During each session, number and diameter of the punctuated follicles and diameter, consistency and cavities in the corpus luteum (CL) were recorded. Follicles were assigned to 3 groups according to their diameter (3 to 5 mm = small follicles; 6 to 8 mm = intermediate follicles; >8 mm = large follicles). Additionally, blood samples were taken at the time of each OPU session and blood P4 concentration was determined using a radioimmunoassay. The COC were categorised as IVP-suitable (round, ≥3 layers of cumulus cells, homo- or heterogeneous ooplasm) or unsuitable according to their morphological quality. All animals showed signs of oestrus accompanied by the presence of large follicles during the course of the OPU sessions. Statistical analysis was performed by an ANOVA followed by a Tukey test. A P-value of <0.05 was considered significant. The mean (±s.e.m.) cycle lengths for all heifers were 23.8 ± 4.6 days. Following the aspiration of a large follicle, a CL-like structure could be detected (referred to as “induced CL”). According to the P4 concentrations, the cycle was divided into 4 phases: natural CL phase (nCL; P4 ≥1 ng mL–1), follicle phase 1 (Fp1; P4 <1 ng mL–1), induced CL phase (iCL; P4 ≥1 ng mL–1), or follicle phase 2 (Fp2; P4 <1 ng mL–1). During the nCL phase, blood P4 concentrations were significantly higher than during the iCL phase (4.9 ± 2.3 ng mL–1, n = 12 vs 3.0 ± 1.6 ng mL–1, n = 10). There were no differences in follicle numbers, the diameter distribution of follicles, recovery rates, or number of retrieved IVP-suitable COC (nCL: 3.1 ± 3.4; Fp1: 3.3 ± 3.7; iCL: 2.7 ± 3.0; Fp2: 3.7 ± 3.7; Table 1). In summary, circulating P4 concentrations had no effect on follicle number, diameter, recovery rate, or IVP suitability of recovered COC. Table 1.Number of follicles, retrieved oocytes, follicle sizes and recovery rates of the ovum pickup (OPU) sessions

57 DIETARY CLA SUPPLEMENTATION AFFECTS LUTEAL GENE EXPRESSION AND PERIPHERAL BLOOD PROGESTERONE CONCENTRATION IN CATTLE

Shortly after parturition the metabolic situation of high-yielding dairy cows is often dominated by a negative energy balance. These effects affect the whole animal and may especially be detected in the reproductive tract, where they result in reduced fertility. An oral supplementation with dietary fats is often used to counteract by reducing milk fat content and, thus, supplying the individual animal with an increased amount of energy. The focus of the present study was to analyse the effects of an oral supplementation with conjugated linoleic acids (CLA) on corpus luteum (CL) function. Healthy Holstein-Friesian cows and heifers were randomly allocated to 2 treatment groups (Group 1: 50 g of CLA day–1 per animal, 2 heifers, 6 cows; Group 2: 100 g of CLA day–1 per animal, 2 heifers, 6 cows) and 1 control group (Ctl; 0 g of CLA day–1 per animal, 3 heifers, 4 cows). Feeding of the supplement began shortly after calving. After calving, all animals were subjected to a standard synchronisation protocol and experienced AI on Day 59 ± 3. Following AI, transvaginal biopsies of the corpus luteum were obtained of pregnant (Group I: n = 4; Group II: n = 4; Ctl: n = 4) and nonpregnant (Group I: n = 4; Group II: n = 4; Ctl: n = 3) animals on Days 6, 13 and 20 post-AI. Animals deemed pregnant on Day 28 were again biopsied on Day 42. Additionally, blood samples were taken from the vena sacralis mediana at the time of each biopsy. The biopsies were analysed regarding the relative abundance of 8 gene transcripts (VEGF, ECE1, PLA2G4A, PTGS2, PTGFR, PPARG, STAR and HSD3B1) via RT-qPCR. Blood samples were analysed for their concentration of progesterone through a radioimmunoassay (RIA). Statistical analysis for both datasets was performed via a 3-way ANOVA with adjoining Tukey test. The expression of 7 of these genes was affected by 1, 2, or all 3 of the following factors: day of cycle (VEGF, ECE1, PLA2G4A, PTGFR, STAR and HSD3B1), pregnancy status (ECE1, PTGFR and HSD3B1) and CLA supplementation (ECE1, PTGS2, PTGFR, STAR and HSD3B1). The effects of the CLA supplementation could be seen as a down-regulation in the mentioned gene transcripts. Progesterone concentrations differed significantly in dependency of the pregnancy status (significantly higher in pregnant vs nonpregnant individuals) of the animals, as well as during the days of the oestrous cycle (physiological progesterone curve with highest values on Day 13 of these samples). An effect of the oral supplementation with CLA could be detected during the early luteal phase (Day 6) where animals that had received 100 g of CLA day–1 had a significantly lower blood progesterone concentration than those receiving 50 g of CLA day–1 or no CLA. In conclusion, dietary CLA supplementation has an effect on luteal gene expression and functionality. The authors thank the DFG (German Research Foundation) for their financial support (PAK286/1; WR154/1-1).

109 INTRAFOLLICULAR GLUCOSE CONCENTRATION HAS AN INFLUENCE ON THE SEX OF BOVINE BLASTOCYSTS PRODUCED IN VITRO

Several factors have been shown to alter the sex ratio of bovine embryos generated in vitro, i.e. the maturity of the oocyte at the time of insemination, the duration of sperm-oocyte co-incubation and the culture conditions after in vitro fertilization. It has been shown that the presence of glucose during in vitro culture reduced the development of female embryos to the blastocyst stage compared with controls cultured in the absence of glucose. The sex ratio of bovine embryos has also been linked with changes in the composition of the follicular fluid in which the oocyte undergoes growth and maturation, i.e. the intrafollicular testosterone concentration. However, no information is available regarding the effect of intrafollicular glucose concentration on the sex ratio of embryos after in vitro production (IVP). The purpose of this study was to determine whether different glucose concentrations in the follicular fluid at the time of cumulus–oocyte complex (COC) collection have an effect on the sex ratio of the resulting blastocysts after IVP. Ovaries from a local abattoir were transported to the laboratory within 2 h of slaughter. Follicles (3–8 mm) were individually dissected and the glucose concentration of each follicle was measured using a blood glucose monitoring system (Freestyle Freedom Lite, Abbott, Germany). Based on a glucose concentration, COC [low glucose: <1.1 mM (group 1) and high glucose: >1.1 mM (group 2)] were pooled in groups and used for blastocyst production employing standard protocols for IVP. Developmental rates were recorded at Day 3 (cleavage) and Day 7/8 (blastocyst stage). Total cell number of blastocysts was determined after Hoechst staining. Sex of the embryos was analysed via PCR using bovine X- and Y-chromosome specific primers. Developmental rates for COC stemming from follicles with different glucose concentrations did not show significant differences (P > 0.05) compared to each other [Cleavage rate: group 1: 81.8 ± 4.7% (93/117); group 2: 79.3 ± 4.9% (94/123); blastocyst rate: group 1: 35.6 ± 5.2% (38/117); group 2: 31.6 ± 5.2% (38/123)]. Total cell numbers were similar in embryos of both groups [Group 1: 117.7 ± 8.1 (n = 18); group 2: 117.2 ± 6.4 (n = 18)]. The overall sex ratio significantly differed (P < 0.05) from 1:1 in favour of females in both groups [Group 1: 85 v. 15% (n = 20); group 2: 63.6 v. 36.4% (n = 22)]. No significant difference (P > 0.05) in the overall sex ratio was detected in blastocysts produced under standard IVP conditions employed in the laboratory [without measurement of follicular glucose concentration, 55.0 v. 45.0%, (n = 20)]. In conclusion, under the conditions used in the present study, the intrafollicular glucose concentration from which the immature COC was collected affects the sex of the resulting embryo after IVP, favouring females. Further studies are needed to confirm these findings in living cows using the ovum pickup technique.

117 EFFECT OF DIFFERENT CRYOPRESERVATION METHODS ON THE QUALITY OF IN VITRO-PRODUCED BOVINE EMBRYOS

In vitro production (IVP) of bovine embryos has been greatly improved over the last couple of years. However, only one-third of the total number of embryos transferred worldwide are of in vitro origin. The IVP embryos still show remarkable differences compared with their in vivo-derived counterparts (i.e. bovine embryos produced in vitro are more sensitive to cryopreservation). So far, vitrification seems to be the most promising method to cryopreserve in vitro-produced bovine embryos. The aim of this study was to determine the effect of 2 different cryopreservation methods on the quality of in vitro-produced bovine embryos at the molecular level using a sensitive RT-qPCR assay. Bovine blastocysts were produced using abattoir ovaries and a standard protocol for IVP (Wrenzycki et al. 2001). They were randomly vitrified employing PBS plus ethylene glycol and DMSO or cryopreserved using a programmable freezer and 1.5 M ethylene glycol. After thawing, embryos from both groups were cultured for 48 h. After 24 h of culture re-expansion rates were documented, and after 48 h hatching rates were documented. After hatching, blastocysts were stored at -80°C for subsequent RT-qPCR analysis. The following gene transcripts known to play important roles during preimplantation development were analyzed: HSP70, GLUT-1, GLUT-3, E-CAD, ZO-1, DNMT3a, IFNτ, DCII. Re-expansion rates were 74.7% (68/91) and 75.0% (87/116) for vitrified and conventionally cryopreserved blastocysts, and 57.1% (52/91) and 55.2% (64/116) of re-expanded embryos hatched. The relative abundances of HSP70, GLUT-1, and ZO-1 transcripts were significantly affected in both groups of cryopreservation compared with the control group (hatched blastocysts without cryopreservation). Conventional cryopreservation had a significant effect on the amount of GLUT-3, DNMT3a, and IFNτ mRNA, whereas vitrification significantly affected DCII transcripts. E-CAD mRNA expression was similar in all groups of embryos. These results suggest that not only the cryopreservation process itself but also the method used to freeze the embryos had a significant influence on the mRNA expression of developmentally important genes in hatched bovine blastocysts. The support of the H.W. Schaumann Stiftung (Germany) and Gynemed Medizinprodukte GmbH & Co. KG (Germany) is gratefully acknowledged.