[Show abstract][Hide abstract] ABSTRACT: Insufficient feed intake during early lactation results in elevated body fat mobilization to meet energy demands for milk production. Hepatic energy metabolism is involved by increasing endogenous glucose production and hepatic glucose output for milk synthesis and by adaptation of postcalving fuel oxidation. Given that cows differ in their degree of fat mobilization around parturition, indicated by variable total liver fat concentration (LFC), the study investigated the influence of peripartum fat mobilization on hepatic gene expression involved in gluconeogenesis, fatty acid oxidation, ketogenesis, and cholesterol synthesis, as well as transcriptional factors referring to energy metabolism. German Holstein cows were grouped according to mean total LFC on d 1, 14, and 28 after parturition as low [<200 mg of total fat/g of dry matter (DM); n = 10], medium (200-300 mg of total fat/g of DM; n = 10), and high (>300 mg of total fat/g of DM; n = 7), indicating fat mobilization during early lactation. Cows were fed total mixed rations ad libitum and held under equal conditions. Liver biopsies were taken at d 56 and 15 before and d 1, 14, 28, and 49 after parturition to measure mRNA abundances of pyruvate carboxylase (PC); phosphoenolpyruvate carboxykinase; glucose-6-phosphatase; propionyl-coenzyme A (CoA) carboxylase α; carnitine palmitoyl-transferase 1A (CPT1A); acyl-CoA synthetase, long chain 1 (ASCL1); acyl-CoA dehydrogenase, very long chain; 3-hydroxy-3-methylglutaryl-CoA synthase 1 and 2; sterol regulatory element-binding factor 1; and peroxisome proliferator-activated factor α. Total LFC postpartum differed greatly among cows, and the mRNA abundance of most enzymes and transcription factors changed with time during the experimental period. Abundance of PC mRNA increased at parturition to a greater extent in high- and medium-LFC groups than in the low-LFC group. Significant LFC × time interactions for ACSL1 and CPT1A during the experimental period indicated variable gene expression depending on LFC after parturition. Correlations between hepatic gene expression and performance data and plasma concentrations of metabolites and hormones showed time-specific relations during the transition period. Elevated body fat mobilization during early lactation affected gene expression involved in gluconeogenesis to a greater extent than gene expression involved in lipid metabolism, indicating the dependence of hepatic glucose metabolism on hepatic lipid status and fat mobilization during early lactation.
Journal of Dairy Science 07/2013; · 2.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Different factors determine the effectiveness of the use of sires in AI. Most important factors are the number of inseminated spermatozoa, the quality of spermatozoa, and the time of insemination. Especially in superovulated animals, the insemination scheme plays in important role to cover the whole ovulation period. The influence of 3 different dosages of spermatozoa (15×10(6), 5×10(6), and 1×10(6)) on fertilization rate was examined in experiment A. In experiment B, one dosage of female and male spermatozoa of 3 different bulls was used for timed AI in 31 heifers. Timed AI in normal-cycling cattle [13h after gonadotropin-releasing hormone (GnRH) application] with detected corpus luteum (Days 8 to 13 of cycle) was carried out after induction of luteolysis and induction of ovulation [GnRH application 60h after prostaglandin F(2α) (PGF2) application]. Embryos and oocytes were flushed from the oviduct of 116 hemicastrated or slaughtered heifers on Day 4 after insemination. The ovulation rate in heifers was 95.4%. Eighty percent of the oocytes or embryos were recovered. The influence of the factors sire, ejaculate, and dosage were tested by GLM analyses of SAS(®) (SAS Institute Inc., Cary, NC, USA). There was no significant difference in the fertilization rate (93.3, 96.2, and 78.8%) and in the proportion of normally developed embryos (84.6, 80.7, and 75.8%) between groups. Significant differences were found in the mean number of accessory sperms/embryo and in the proportion of embryos with >10 accessory sperms/embryo or without accessory sperms; however, the proportion of intact embryos was similar. Using sexed semen in experiment B, similar results were obtained after flushing of the oviducts on Day 4 after insemination of hemicastrated or slaughtered animals. In total, an ovulation rate of 91.7%, a recovery rate of 70%, and a fertilization rate of 86.8% were obtained. There were no differences between female- and male-sorted spermatozoa and the control group. In experiment C, altogether 13 heifers were treated 8 times with FSH for 4 days starting between Day 8 to 12 of estrous cycle. Prostaglandin F(2α) was given 48 and 60h after the first FSH injection. Insemination with sexed semen (n=5 heifers) and with unsorted semen (n=8; 15×10(6) and 1×10(6)) was done at 55 and 71h after induction of luteolysis. Flushing of the uterus was performed on Day 7. Using the time-oriented insemination after superovulation of animals, fertilization rates varied between 65 and 85%. There was no difference between groups regarding the number of transferable embryos (5.5, 4.9, and 4.8). The results demonstrate that the application of an approved insemination schedule may accomplish high fertilization rates after insemination with sexed or reduced dosages of spermatozoa in normal-cycling as well as superovulated cattle.
Reproduction Fertility and Development 12/2012; 25(1):159-60. · 2.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fat mobilization to meet energy requirements during early lactation is inevitable because of insufficient feed intake, but differs greatly among high-yielding dairy cows. Therefore, we studied milk production, feed intake, and body condition as well as metabolic and endocrine changes in high-yielding dairy cows to identify variable strategies in metabolic and endocrine adaptation to overcome postpartum metabolic load attributable to milk production. Cows used in this study varied in fat mobilization around calving, as classified by mean total liver fat concentrations (LFC) postpartum. German Holstein cows (n = 27) were studied from dry off until d 63 postpartum in their third lactation. All cows were fed the same total mixed rations ad libitum during the dry period and lactation. Plasma concentrations of metabolites and hormones were measured in blood samples taken at d 56, 28, 15, and 5 before expected calving and at d 1 and once weekly up to d 63 postpartum. Liver biopsies were taken on d 56 and 15 before calving, and on d 1, 14, 28, and 49 postpartum to measure LFC and glycogen concentrations. Cows were grouped accordingly to mean total LFC on d 1, 14, and 28 in high, medium, and low fat-mobilizing cows. Mean LFC (±SEM) differed among groups and were 351 ± 14, 250 ± 10, and 159 ± 9 mg/g of dry matter for high, medium, and low fat-mobilizing cows, respectively, whereas hepatic glycogen concentrations postpartum were the highest in low fat-mobilizing cows. Cows in the low group showed the highest dry matter intake and the least negative energy balance postpartum, but energy-corrected milk yield was similar among groups. The decrease in body weight postpartum was greatest in high fat-mobilizing cows, but the decrease in backfat thickness was greatest in medium fat-mobilizing cows. Plasma concentrations of nonesterified fatty acids and β-hydroxybutyrate were highest around calving in high fat-mobilizing cows. Plasma triglycerides were highest in the medium group and plasma cholesterol concentrations were lowest in the high group at calving. During early lactation, the decrease in plasma glucose concentrations was greatest in the high group, and plasma insulin concentrations postpartum were highest in the low group. The revised quantitative insulin sensitivity check index values decreased during the transition period and postpartum, and were highest in the medium group. Plasma cortisol concentrations during the transition period and postpartum period and plasma leptin concentrations were highest in the medium group. In conclusion, cows adapted differently to the metabolic load and used variable strategies for homeorhetic regulation of milk production. Differences in fat mobilization were part of these strategies and contributed to the individual adaptation of energy metabolism to milk production.
Journal of Dairy Science 11/2012; · 2.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The objectives of this study were to obtain relevant blood flow indices of umbilical arteries (UmA) of porcine fetuses using a laparoscopic ultrasound probe and to relate these data with fetal size at early to mid gestation. Fetal parameters and flow indices, i.e., fetal length and area, fetal heart rate (FHR), systolic pulse duration (T1), interpulse duration (T2), T2/T1 ratio, peak systolic velocity (PSV), time averaged velocity (TAV), resistance index (RI) and pulsatility index (PI), were measured in 182 fetuses of 26 pregnant Landrace gilts on pregnancy day (PD) 36 (122 fetuses from 17 gilts), PD42 (19 fetuses from 3 gilts) and PD51 (42 fetuses from 6 gilts). Fetal heart rate was higher on PD36 than on PD42 (P<0.05). No differences (P>0.05) were obtained concerning systolic pulse duration, flow velocities and RI. On PD42, the PI was lower (P<0.05), while the interpulse duration (P=0.06) and T2/T1 ratio tended (P=0.08) to be higher on PD42 compared with PD36 and to PD51. To find differences in UmA blood flow parameters concerning fetal size, i.e., fetal length, fetuses were retrospectively grouped as follows: small (lower 25%), medium (mean 50%) and large (upper 25%), respectively. Although, fetuses differed in size (P<0.001) within and between days of pregnancy, FHR, PSV, TAV, RI and PI did not differ (P>0.05) among the size classes. Only systolic pulse duration tended to be longer (P=0.05) in large compared with small fetuses on PD36, and interpulse duration was lower in large fetuses on PD36 in comparison with PD51 (P<0.05). Though there was no link between fetal blood flow indices and fetal intrauterine growth retardation (IUGR), with further studies based on these flow indices, it might be possible to evaluate nutrient- or stress-related influences on fetal growth and development, particularly in the case of IUGR.
Journal of Reproduction and Development 01/2012; 58(2):243-7. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The cytoskeleton, consisting of complex and dynamic systems of structural filaments, intermediate filaments and microtubules, is not only a structural element but also contributes to many cellular processes such as functional compartments, transportation, mitosis, secretion, formation of cell extensions, and intercellular communication. Suggestions in rat 2-cell embryos that abnormal distributions of cytoskeletal proteins occurred following the initiations of developmental arrest and our former studies showing reduced intercellular contact zones in cloned bovine embryos prompted us to conduct comparative studies on 8-cell stage bovine embryos from nuclear transfer (NT), in vitro, and in vivo production. Immunohistochemistry and Laser-Scanning-Microscopy facilitated detection of cytoskeleton proteins--alpha-tubulin, F-actin, beta-catenin, and the cell adhesion protein cadherin; image and cluster analysis were subsequently used to study the distribution pattern of the proteins, whereas Western blot was carried out for their qualitative and quantitative analysis. The maximum fluorescence intensity of stained alpha-tubulin was observed in the cloned and the in vitro embryos. A significant higher intensity of staining for F-actin was observed in the in vivo and in vitro embryos. In contrast, Western blot revealed no differences of actin, tubulin, and catenin between the three tested groups whereas a lower abundance of cadherin proteins in the cloned embryos was visible. The distribution of actin filaments in cloned embryos was more centric or one-sided and not peripheral whereas the stained spots of catenin were smaller in comparison to in vivo or in vitro produced embryos. These differences recorded in the distribution patterns may be associated with cell physiological processes related to an influenced actin-catenin-cadherin system. In conclusion, reduced intercellular contacts coupled with abnormal distribution of cytoskeletal proteins seem to play an important role in the developmental arrest encountered normally at the 8-cell stage in bovine cloned embryos.
Molecular Reproduction and Development 08/2008; 75(7):1109-19. · 2.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Feeding rumen-protected fat (RPF) is an alternative to increase energy density of the diet and therefore energy intake in dairy cows. To investigate metabolic and endocrine changes in dairy cows fed either a diet containing RPF (FD) or a control diet with an increased amount of cornstarch (SD), 3 Holstein cows (83 +/- 1 d in milk) were fitted with catheters in the portal vein, a mesenteric artery, and 2 mesenteric veins. Cows were fed consecutively SD and FD for 3 wk, respectively. In FD, cornstarch [92 g/kg of dry matter (DM)] was replaced by 50 g of RPF/kg of DM (mainly C16:0 and C18:1). Tracer infusions of NaH(13)CO3 and D-[U-(13)C6]glucose were performed into a jugular vein to measure rate of appearance and oxidation of glucose. Arterial and portal blood samples were collected to measure concentrations of glucose, lactate, volatile fatty acids, nonesterified fatty acids, beta-hydroxybutyrate, triglycerides, AA, insulin, and glucagon. Concomitantly, para-aminohippurate was infused into a mesenteric vein for measurement of portal plasma flow. Although DM intake was slightly lower in FD, protein and energy intakes were unaffected by diets. Milk and lactose yields were higher in FD than SD. Arterial plasma glucose concentration was lower with FD than SD, whereas nonesterified fatty acid and triglyceride concentrations were higher in FD. Glucagon concentration and glucagon-to-insulin ratio were both augmented by FD feeding. When feeding FD, greater milk and lactose yields, but not energy-corrected milk, were associated with elevated lipid status and higher glucagon concentrations but occurred despite lower plasma glucose concentration and were not linked with changes in whole body glucose rate of appearance. This study suggests a glucose-sparing effect allowing an enhanced lactose synthesis when feeding RPF.
Journal of Dairy Science 02/2008; 91(1):208-17. · 2.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: ContentsThe surge of LH and the process of ovulation were determined in nine gilts by means of repeated laparoscopy after synchronization of estrus and stimulation of ovulation using 50 μg Gn-RH (Gonavet “Berlin-Chemie”). The mean duration between Gn-RH application and the beginning and the completion of ovulation was 35.5 ± 2.7 h and 39.7 ± 1.9 h, respectively. A period of 31.1 ± 2.2 h and 36.4 ± 2.5 h was between the peak of LH and the beginning and the completion of ovulations. The mean duration of ovulation, including the first up to more than 80% of ovulated follicles, was 5.9 ±1.7 h. About 20% of all follicles/gilt ovulated in a period of 2.9 ± 1.1 h. The duration of the ovulation from 20% up to more than 80% of the follicular population was 3.0 ± 0.7 h.Inhalt: Beziehungen zwischen derdurch exogenes Gn-RH induzierten LH-Ausschüttung und der Ovulationsdauer bei JungsauenDie LH-Ausschüttung und der Ovulationsverlauf mittels wiederholter Laparoskopie wurden bei 9 Jungsauen nach Brunstsynchronisation und Stimulation der Ovulation mit 50 μg Gn-RH (Gonavet “Berlin-Chemie”) bestimmt. Die Zeitdauer zwischen der Gn-RH Applikation und dem Beginn bzw. Abschluβ der Ovulation betrug 35,5 2,7 h bzw. 39,7 1.9 h. Zwischen dem LH-Peak und dem Beginn bzw. Abschluβ der Ovulation wurde ein Intervall von 31,1 2,2 h und 36,4 2,5 h ermittelt.Die durchschnittliche Ovulationsdauer, gemessen von der Ovulation des ersten bis zu mehr als 80% der Follikel, betrug 5,9 1,7 h. Die Untersuchungen zeigten, daβ die Ovulation der einzelnen Follikel nicht gleichmäβig verläuft. Etwa 20% aller Follikel/Jungsau ovulierten innerhalb von 2,9 1,1 h. Die Dauer der Ovulation von 20% bis mehr als 80% der Follikelpopulation betrug 3,0 0,7 h.
[Show abstract][Hide abstract] ABSTRACT: Since the first successful nuclear transfer (NT) experiments were carried out, various somatic cell types have been used as donor cells for production of cloned animals. In most experiments, fibroblasts are used since they only need to be isolated and cultivated. Recently, some researchers have shown that different cell cultures from different sources possess different capacities to support preimplantation development of NT embryos. The blastocyst rates obtained in our previous studies varied and were as high as 45% in relation to the number of reconstructed embryos. This led us to question whether the origin and culture conditions of the defined male and female fibroblast lines could be responsible for the differences in developmental potency. Taking all our results into consideration, we conclude that different fibroblast lines recovered from the same tissue and cultivated under equal culture conditions could produce dramatically different blastocyst rates. The influence of cell line itself is higher than the influence of passage number. The observed effects of cell cycle stage, chromosomal aberrations, and diminished vitality are important but not sufficient to discriminate well-qualified nuclear donor cells. We speculate that some epigenetically regulated deviations in the gene expression program are responsible for these phenomena. Explanation of the underlying mechanisms should contribute to better understanding of epigenetic reprogramming and may ultimately assist reprogramming in the laboratory.
Journal of Reproduction and Development 09/2007; 53(4):737-48. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cellular coherence and communication, thus cell-to-cell contact is an indispensable premise to sustain the formation of complex, multi-cellular organisms. We have analyzed intercellular contact lengths in NT-cloned bovine embryos compared to the in vivo or in vitro produced counterparts. Therefore, ultrastructural analysis was carried out by transmission electron microscopy (TEM) at the 8-cell and blastocyst stage of development. To obtain embryos generated in vivo, oviducts of superovulated cows were flushed 3 days after insemination, subsequent to slaughter. Standard in vitro maturation (IVM) and -fertilization (IVF) were utilized to obtain in vitro embryos. Cloned embryos by somatic nuclear transfer were produced by the handmade cloning (HMC) procedure. The points of apposition/focal contact points (CPs) between the blastomeres were of the shortest order in cloned embryos (236 +/- 135 nm) and of highest order in the in vivo produced embryos (2,085 +/- 1,540 nm), although no significant differences regarding the blastomere sizes in the various groups of 8-cell embryos could be established. In summary, the CP lengths in case of in vitro and in vivo 8-cell embryos were, on an average, five or nine times longer, respectively, than in the case of the cloned embryos. These differences of CP lengths vanished in embryos reaching the blastocyst stage of embryonic development in all the three groups of embryos. The observed differences of intercellular contact length at distinct stages of embryonic development could be responsible for differences in intercellular communication between the blastomeres at the beginning of cellular differentiation. These may be one reason for the lower developmental competence of cloned (NT) embryos.
Molecular Reproduction and Development 07/2007; 74(6):775-84. · 2.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this investigation was to examine the chromatin configuration of the nucleus, pattern of mitochondrial aggregation and mitochondrial activity in parallel studies in the same horse oocytes. Horse oocytes recovered by ultrasound-guided follicle aspiration in vivo were classified according to two main initial cumulus morphologies as having compact or expanded cumulus. The percentage of oocytes with a diplotene meiotic configuration at the time of recovery from the follicles was highest in compact oocytes. Oocytes with expanded cumulus layers at the time of recovery matured more rapidly in vitro and reached a proportion >50% at the metaphase II stage (M 2) sooner during in vitro maturation (IVM), than did compact oocytes. The mitochondrial aggregation pattern changed from finely distributed (Type 1) through crystalline (Type 2) to an aggregated, granulated appearance (Type 3) during IVM. The pattern of mitochondrial aggregation at the time of recovery was associated with the initial cumulus morphology of the oocyte, in that compact oocytes had a higher proportion of Type 1 aggregation, whereas expanded oocytes had a higher proportion of Type 3. The fluorescence intensity of metabolic active mitochondria, measured by fluorescence intensity (Em 570) per oocyte after MitoTracker CMTM Ros orange labelling, increased in the oocytes during IVM and depended on initial cumulus investment. Oocytes with the granulated type of aggregated mitochondria Type 3 had the highest level of metabolic activity and were in more progressed stages of meiosis (A 1-M 2). Oocytes initially having expanded layers of cumulus reached significantly higher levels of mitochondrial activity after IVM than did oocytes initially having compact cumuli. During resumption of meiosis the mitochondrial activity of oocytes with initially expanded cumulus increased continuously up to M 2, whereas in oocytes from compact cumulus-oocyte complex (COC), the activity declined after A 1/T 1 stages of meiosis.
Reproduction in Domestic Animals 04/2007; 42(2):176-83. · 1.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of the study was to investigate the effect of the GnRH agonist Buserelin given on day 10 after ovulation on pregnancy rate and concentrations of progesterone and LH. Altogether 191 warmblood mares were used for two trials. Fresh or frozen/thawed semen from 27 stallions was used for A.I. In trial A 171 mares received either Buserelin (Receptal, Hoechst, Germany, 40 microg/animal) or 10 ml 0.9% NaCl (placebo). On day 16 after A.I. pregnancy diagnosis was performed by ultrasound scanning of the uterus. For statistical analysis, data were analyzed by a mixed model, with four fixed factors (treatment, type of spermatozoa, A.I. number, reproductive status of the mare) and a random factor (stallion). Least Square Means (LSM) for pregnancy rate were 46.0% in GnRH agonist treated mares and 36.4% in the control group (P=0.22). In trial B 20 lactating and cycling mares were used for endocrine studies. Blood samples were recovered for analyses of progesterone and LH from days 0 to 11. The mean progesterone concentrations increased continuously from days 0 to 8 after ovulation in both groups (GnRH group: from 0.81+/-0.48 to 5.47+/-0.48 ng/ml, control group: from 0.63+/-0.68 to 5.83+/-0.68 ng/ml). Moreover, the progesterone concentrations from days 9 to 11 were not different between the GnRH and the control group. In contrast to this LH concentrations were markedly influenced by the GnRH agonist. On day 10 LH concentrations were significantly higher in GnRH agonist treated than in placebo treated animals. From the data obtained from individual animals it can be concluded that GnRH agonist, given during luteal phase may have different effect on luteal function.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to prove if oxidation-reduction levels in the follicular fluid were new functional indices of follicular health and whether there was a high level of accordance with endocrinological parameters and with the growth stage as detected by ultrasound monitoring of individual follicles during the oestrous cycle in mares. Follicles were classified as growing and regressing follicles using ultrasonography. Altogether 48 follicles with a diameter from 20 to 56 mm were aspirated by transvaginal ultrasound guided follicular aspiration. Follicular concentration of oestradiol and progesterone in relation to the diameter of growing follicles showed correlations of r = 0.64 and r = 0.57, respectively. The redox potential derived index D2 varied from -448 to +431 in the collected fluids of the follicles. The accordance of the judgement of all follicles using both complexes of methods - endocrinological and ultrasonographic parameters vs. analysis of oxidation and reduction levels - reached 72.5%. This finding has shown that parameters of redox reactions do not correlate closely with the stage of follicular growth or regression as determined by in vivo scanning of ovaries or by assessment of follicular steroid concentrations. However, the measurement of redox potentials offers an opportunity to examine the whole process of metabolism in follicular cells and to forecast impairments of cellular performances. Changes of redox parameters in growing follicles enable an earlier prediction of their further development. The data demonstrate that growing and regressing follicles do not represent nonatretic, early atretic and atretic follicles, respectively.
[Show abstract][Hide abstract] ABSTRACT: The present study was conducted to assess effects of the gonadotropin-releasing hormone agonist (GnRHa) triptorelin in dairy heifers. The peptide was released from a commercial 4-week depot formulation (Decapeptyl Depot) administered at animals' estrus (day 0). First experiment (EXP I, n=5), which was aimed to explore the availability of peptide, detected a maximum of triptorelin concentration between day 2 and 5 after depot injection, and the peptide remained detectable by RIA in peripheral blood for about 3 weeks. In further experiments, the peptide release was terminated on day 9 (EXP II, n=16) or day 21 (EXP III, n=47). Treatment effects were studied on follicular development, the characteristics of cumulus-oocyte complexes (COCs) (EXP II; EXP IIIa) and secretions of LH and progesterone (EXP IIIb). Results showed that the occurrence of the pre-ovulatory LH surge was more uniform in treated heifers than that in controls. The duration of ovulation periods was similar amongst the heifers of EXP II, but more compact amongst those of EXP III each compared with the respective controls. Post-ovulatory, the number of LH pulses was significantly reduced by treatment, whereas both basal LH and progesterone concentrations were elevated on a few days. Follicular growth was reduced only by the prolonged influence of the GnRHa. There were increased proportions of both degenerated COCs and immature oocytes from small follicles (<3mm in diameter), and meiotic configuration and quality of oocytes isolated from follicles 3-5mm were changed after the prolonged, 21-day treatment. These results indicate that a continuous influence of a GnRHa over more than 1 week may increasingly impair the development of bovine follicles and oocytes. This may have some significance for the development of novel GnRH-based techniques in regulating the reproductive function in cattle.
[Show abstract][Hide abstract] ABSTRACT: The objective of the experiment was to study follicular dynamics and characteristics of ovulations in dairy heifers after application of the Ovsynch protocol in the last third of estrous cycle. Therefore, altogether 27 regular cycling Holstein heifers were given an injection of GnRH on day 14, 16 or 18 (9 heifers each in group 1 to 3) of the estrous cycle. All heifers were administered PGF2alpha seven days later. Blood was collected for progesterone determination, just before, 24 hours and 48 hours after the PGF2alpha injection. A second injection of GnRH was administered 48 hours after the PGF2alpha injection. Ovarian follicular dynamics were monitored by frequent ultrasound scanning of the ovaries after first and second GnRH injection. Altogether 22 of 27 heifers (81.5%) ovulated 27 to 33 h after first GnRH injection. In 4 heifers ovulations were recorded 45 to 51 h after first GnRH application. Mean intervals between GnRH application and ovulation were 33.0, 33.6 and 28.3 h, respectively. At the time of PGF2alpha injection mean progesterone concentrations were similar in groups 1 and 2, but significantly lower than in group 3. After the second GnRH treatment 5,6 and 8 heifers had ovulations. The average intervals from the second GnRH treatment to ovulation were 24.8, 24.0 and 24.4 h respectively. The results show that Ovsynch is not sufficient to ensure synchronisation of oestrous and ovulation in each animal treated.
Berliner und Münchener tierärztliche Wochenschrift 01/2006; 119(11-12):512-5. · 0.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The fate of carbon from long-chain fatty acids and glucose in dairy cows which were fed with protected fat was studied using stable isotope technique. The experiment was carried out on two groups of dairy cows (n=16 in each group) during the first 15 weeks of the lactation period. The cows were fed isoenergetic and isoproteinogenous diets based on corn silage. About 1.8 kg of tapioca starch in the diet of the starch group was substituted by about 0.7 kg of rumen protected fat (Ca salts of palm oil and soybean oil) in the diet of the fat group. The carbon atoms of dietary fat were naturally depleted in 13C as compared to carbon atoms of starch. Daily milk performance and lactose output were significantly (P < 0.05) higher among the cows fed with fat diet. In comparison to the starch group, the enrichment of milk fat with 13C was significantly lower, while that of breath CO2 was significantly higher in the fat group (P < 0.05). This means the fatty acids were incorporated into milk fat in preference to metabolic oxidation. Further studies showed that blood glucose is oxidized to a lower extent and is used for the synthesis of lactose to a higher proportion if the cows were fed with the fat diet. The glucose entry rate into the body glucose pool was not different between the diets. In conclusion, the dietary fatty acids perform a glucose sparing effect and improve the glucose supply for the mammary gland.
DTW. Deutsche tierärztliche Wochenschrift 12/2005; 112(11):423-5. · 0.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To enable us to handle a large number of oocytes at a given time and to have an increased throughput of cloned embryos, we attempted the Handmade cloning (HMC) technique, a zona-free method of bovine somatic cell nuclear transfer. Our objective was to study the developmental competence of the HMC derived embryos obtained using different types of somatic cells. A total of 6,874 cumulus-oocyte-complexes were used with either 7th or 11th passage fibroblasts (1st and 2nd groups, respectively), which were prepared from male animals, or granulosa cells (3rd group) as nuclei donors. The average cleavage rate was 65%, accompanied by a blastocyst rate of just 2% for the cleaved products and 5% for the >8-cell embryos, and there was no significant difference between the three groups. Out of 27 blastocysts recovered, 22 blastocysts were transferred to 22 recipients, resulting in two pregnancies. One pregnancy was lost after the fourth week while the other progressed to full term with the birth of a male calf. This first successful cloning of a male calf with the HMC technique in Europe indicates the successful adoption and establishment of this technique in our laboratory, and that this technique can be successful in producing viable embryos.
Journal of Reproduction and Development 09/2005; 51(4):465-75. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Platelet-activating factor (PAF) and its receptors are involved in inflammatory-like processes of the uterus associated with increased vascular permeability. PAF is supposed to be influenced by ovarian steroid hormones. The present study was undertaken to examine whether progesterone (P(4)), estradiol (E(2)) or PAF influence the PAF receptor gene expression in perfused endometrial explants derived from ovariectomized bovine. Furthermore, we identified the cell types in which the PAF receptor gene and protein are expressed. In endometrial explants, applications of 10 nM P(4) or 10nM P(4) plus 10 nM E(2) for 24 h induced elevated transcript levels of PAF receptor in comparison to the controls or after treatment with 1 nM E(2). When explants were administered 10 nM E(2), a slight decrease in the transcript level was recorded. After treatment of explants with PAF, no significant changes in PAF receptor mRNA expression was observed compared to the control group. We demonstrate that PAF receptor immunoreactivity and mRNA are detected mainly in the luminal epithelium, epithelial cells of the superficial glands and to a lesser degree in stroma. Levels of PAF receptor mRNA in bovine endometrial explants were correlated with PAF receptor protein localization assessed by immunohistochemistry. The regulation of PAF receptor by progesterone in bovine endometrial explants suggests that PAF is involved in the physiological process of reproduction.