A phenotypical approach to the effects of production traits, parturition, puerperium and body condition on commencement of luteal activity in high yielding dairy cows.

The interval from calving to commencement of luteal activity (CLA) was determined by progesterone measurements from milk samples obtained once a week until the 14th week post-partum in 513 German Holstein cows in first to third parity. Milk samples were analyzed by an "on-farm" device (eProCheck(®), Minitüb, Germany) and simultaneously by RIA. The objective of this study was to examine the effect of milk yield, protein content and body condition of a cow on the CLA post-partum.

Chromatin and cytoplasmic characteristics of equine oocytes recovered by transvaginal ultrasound-guided follicle aspiration are influenced by the developmental stage of their follicle of origin.

Dynamic follicular changes occur during the equine estrus cycle, but little is known about their impact on the properties of recovered oocytes. The aim of this study was to characterize the cytoplasmic and chromatin status of equine oocytes in relation to the time of recovery during the follicle wave. Transvaginal ultrasound-guided follicle aspiration was performed two times in relation to the follicle wave: estrus-subordinate, from the subordinate follicles of mares in estrus, 24 hours after human chorionic gonadotropin stimulation of a dominant preovulatory follicle, and new-wave, from the follicles of the subsequent induced follicular wave, at the time of dominant follicle divergence (largest follicle 23 mm diameter).

Laparoscopy guided Doppler ultrasound measurement of fetal blood flow indices during early to mid-gestation in pigs.

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.

4E-BP1 degradation and eIF4E truncation occur spatially distinctly in the porcine uterine epithelia and are features of noninvasive implantation in the pig.

The implantation of the blastocyst into the endometrium is an indispensable premise for successful embryonic development. This process is regulated by maternal and embryonic signals that influence gene expression at the translational level, among other processes. Recently, we have shown that proteolytical cleavage of the prototypical 25-kDa, mRNA cap-binding protein eIF4E produces a stable variant with a molecular mass of approximately 23 kDa exclusively in the porcine endometrium during implantation.

Influence of synthetic lamprey GnRH-III on gonadotropin release and steroid hormone levels in gilts.

Based on the supposition that lamprey GnRH-III (lGnRH-III) elicits FSH releasing activity in swine, synthetic lGnRH-III (peforelin, Maprelin® XP10) was used in puberal estrus synchronized gilts. The secretion of reproductive hormones FSH, LH, estradiol and progesterone was analyzed, and follicle growth and ovulation recorded. Altogether, 24 German Landrace gilts were treated after an 18-day long synchronization of the estrus cycle with Regumate® as follows: 48 h after the last Regumate® feeding they received im either 150 μg Maprelin® XP10 (lGnRH-III, group Maprelin, n = 6), 50 μg Gonavet Veyx® (GnRH-I agonist, group GnRH, n = 6), 850 IE Pregmagon® (eCG, group eCG, n = 6) or saline (group Control, n = 6).

[Use of GnRH in livestock production--current position and new research data].

The hypothalamic gonadotropin-releasing hormone (GnRH) is seen as the key hormone of neuroendocrine regulation of reproduction. The ability of GnRH and its analogues to stimulate the release of the gonadotropins FSH and LH is world-wide utilized for various veterinary purposes, including treatment of certain hormone-dependent disturbances and stimulation of ovulation in controlled breeding programmes. A large difference is striking, however, when comparing the efficiencies reported.

Molecular and subcellular characterisation of oocytes screened for their developmental competence based on glucose-6-phosphate dehydrogenase activity.

Oocyte selection based on glucose-6-phosphate dehydrogenase (G6PDH) activity has been successfully used to differentiate between competent and incompetent bovine oocytes. However, the intrinsic molecular and subcellular characteristics of these oocytes have not yet been investigated. Here, we aim to identify molecular and functional markers associated with oocyte developmental potential when selected based on G6PDH activity.

Alterations in transcript abundance of bovine oocytes recovered at growth and dominance phases of the first follicular wave.

Background: Oocyte developmental competence is highly affected by the phase of ovarian follicular wave. Previous studies have shown that oocytes from subordinate follicles recovered at growth phase (day 3 after estrus) are developmentally more competent than those recovered at dominance phase (day 7 after estrus). However, the molecular mechanisms associated with these differences are not well elucidated.

Donor cell lines considerably affect the outcome of somatic nuclear transfer in the case of bovines.

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.

Molecular analysis of maturation processes by protein and phosphoprotein profiling during in vitro maturation of bovine oocytes: a proteomic approach.

Cellular maturation and differentiation processes are accompanied by the expression of specific proteins. Especially in oocytes, there is no reliable strict linear correlation between mRNA levels and the abundance of proteins. Furthermore, the activity of proteins is modulated by specific kinases and phosphatases which control cellular processes like cellular growth, differentiation, cell cycle and meiosis.

[Follicle dynamics and characteristics of ovulation in heifers after Ovsynch treatment in the last third of the estrous cycle].

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.

Effect of recombinant bovine somatotropin (rbST) on cytoplasmic maturation of bovine oocytes and their developmental competence in vitro.

The objectives of this study were to evaluate the effects of recombinant bovine somatotropin (rbST) on the nuclear and cytoplasmic maturation of bovine oocytes and their further developmental competence to blastocysts in vitro. We analyzed the mitochondrial activity and concentration of intracellular stored calcium ([Ca(2+)](is)) in matured oocytes and the morphology and chromatin status of produced embryos after in vitro fertilization. Cumulus-oocyte complexes were incubated in TCM 199 containing 10% fetal calf serum (control medium 1: CM 1) or 10% estrus cow serum (control medium 2: CM 2).

Developmental competence of HMC(TM) derived bovine cloned embryos obtained from somatic cell nuclear transfer of adult fibroblasts and granulosa cells.

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.

[Relationship between oxidant stress and milk productivity in dairy cows].

An imbalance between formation and detoxification of oxygen radicals leads to oxidant stress that may increase in more intense oxidative metabolism caused by a high intake of metabolizable energy to provide metabolic intermediates for the milk synthesis and secretion. This hypothesis was tested using dairy cows and the concentration of hydroperoxides in lipids (LHP) extracted from circulative lipoprotein particles of low and very low density (LDL and VLDL/chylomicrons) as oxidant stress indicator. The particles were prepared by ultracentrifugation of serum obtained by coccygeal bleeding (13 cows, 1.

Superovulation in cattle: practical aspects of gonadotropin treatment and insemination.

Embryo transfer (ET) in cattle has been used for the realisation of breeding programmes world-wide for more than 20 years. The efficiency of breeding technology, i.e.