The Influence of Three Commercial Soy Lecithin-Based Semen Extenders and Two Spermatozoa Concentrations on the Quality of Pre-Freeze and Post-Thaw Ram Epididymal Spermatozoa

There are limited studies on the factors affecting the success of ram epididymal spermatozoa (REPS) cryopreservation. On this note, the current study assessed the influence of three commercial soy lecithin-based semen extenders, AndroMed® (AND), BioXcell® (BIO), and OviXcell® (OVI), and two concentrations (400 × 106 vs. 200 × 106 spermatozoa/mL) on the pre-freeze and post-thaw quality of REPS. The REPS were retrieved from nine adult rams' testes and diluted with each of the three extenders to both concentrations. Straws were frozen manually. Standard motility (SMP) and kinematic parameters (KPs) were assessed via a CASA, while spermatozoa viability, morphology, and acrosomal integrity were assessed via the Kovács-Foote staining technique. The concentration did not significantly affect the pre-freeze and post-thaw SMP and KPs of REPS. BIO and OVI had significantly higher pre-freeze and post-thaw BCFs, post-thaw VAP, and the percentage of all intact heads than AND. In contrast, AND had a significantly lower percentage of REPS with tail defects than BIO and OVI. The 400 × 106 spermatozoa/mL concentration resulted in a significantly higher percentage of all intact heads than the 200 × 106 spermatozoa/mL concentration. Freezing significantly increased tail defects and decreased the percentage of REPS with distal cytoplasmic droplets. The cryopreservation of REPS at the 400 × 106 spermatozoa/mL concentration is recommended. All three extenders must be optimized to preserve the viability, membrane integrity, and better normal morphology of REPS; the reason for increased tail abnormality after the freezing/thawing process needs to be studied.

The impact of retrieval method and breed on the motility and kinematic parameters of fresh and post-thaw ram epididymal spermatozoa

This study was conducted to develop ideal post-mortem gamete retrieval and conservation methods to establish a Hungarian ex-situ in vitro gene bank. Pairs of testes from German Mutton Merino (n = 7) and Hungarian Black Racka (n = 7) rams were collected at a slaughterhouse, transported to the laboratory and stored overnight (4-5 °C) before processing. Post mortem ram epididymal spermatozoa (REPS) were obtained from the cauda epididymidis by slice or incision methods. Fresh samples were extended to 200 × 106/mL cell concentration, filled into mini straws and equilibrated at 5 °C for 2 h. Freezing was performed manually in a Styrofoam box. The fresh and post-thaw total motility, progressive motility and kinematic parameters of REPS were assessed using the CASA technique. The collection method did not affect significantly the fresh and post-thaw motility and kinematic parameters. Merino had higher (P < 0.05) testicular weight. Racka had significantly better fresh and post-thaw linear movement but had statistically the same (P > 0.05) cryotolerance as Merino. In conclusion, both collection methods were found suitable for REPS retrieval. The REPS from Racka exhibited better linear movement values than those from the Merino breed. The cryotolerance of REPS of both breeds was comparable.

Noninfectious Causes of Pregnancy Loss at the Late Embryonic/Early Fetal Stage in Dairy Cattle

In cattle, initial pregnancy diagnosis takes place during the late embryonic/early fetal stage of gestation. From this point onward, pregnancy loss may occur in up to one fifth of pregnancies before the initial pregnancy diagnosis is confirmed. This means the early identification of risk factors is a key part of pregnancy diagnosis and herd management. The various factors responsible for pregnancy losses are classified into infectious and noninfectious. Among the noninfectious causes, several dam-related (circumstances of the individual pregnancy or milk production) and herd-related factors causing stress have been well established. In this review, we summarize the impacts of these noninfectious factors and predict associated risks of pregnancy loss.

Salivary cortisol as a non-invasive approach to assess stress in dystocic dairy calves

The intensity and the magnitude of saliva cortisol responses were investigated during the first 48 h following birth in newborn dairy calves which underwent normal (eutocic, EUT, n = 88) and difficult (dystocic, DYS, n = 70) calvings. The effects of parity and body condition of the dam, the duration of parturition, the time spent licking the calf, the sex and birth weight of the calf were also analyzed. Neonatal salivary cortisol concentrations were influenced neither by factors related to the dam (parity, body condition) nor the calf (sex, birth weight). The duration of parturition and the time spent licking the calf also had no effect on salivary cortisol levels. Salivary cortisol concentrations increased rapidly after delivery in both groups to reach their peak levels at 45 and 60 min after delivery in EUT and DYS calves, respectively supporting that the birth process means considerable stress for calves and the immediate postnatal period also appears to be stressful for newborn calves. DYS calves exhibited higher salivary cortisol concentrations compared to EUT ones for 0 (P = 0.022), 15 (P = 0.016), 30 (P = 0.007), 45 (P = 0.003), 60 (P = 0.001) and 120 min (P = 0.001), and for 24 h (P = 0.040), respectively. Peak levels of salivary cortisol and the cortisol release into saliva calculated as AUC were higher in DYS than in EUT calves for the 48-h of the sampling period (P = 0.009 and P = 0.003, respectively). The greater magnitude of saliva cortisol levels in DYS calves compared to EUT ones suggest that difficult parturition means severe stress for bovine neonates and salivary cortisol could be an opportunity for non-invasive assessment of stress during the early neonatal period in cattle.

Effect of single-nucleotide polymorphisms on specific reproduction parameters in Hungarian Large White sows

The aim of this study was to reveal the effect of single-nucleotide polymorphisms (SNPs) on the total number of piglets born (TNB), the litter weight born alive (LWA), the number of piglets born dead (NBD), the average litter weight on the 21st day (M21D) and the interval between litters (IBL). Genotypes were determined on a high-density Illumina Porcine SNP 60K BeadChip. Data screening and data identification were performed by a multi-locus mixed-model. Statistical analyses were carried out to find associations between individual genotypes of 290 Hungarian Large White sows and the investigated reproduction parameters. According to the analysis outcome, three SNPs were identified to be associated with TNB. These loci are located on chromosomes 1, 6 and 13 (-log₁₀P = 6.0, 7.86 and 6.22, the frequencies of their minor alleles, MAF, were 0.298, 0.299 and 0.364, respectively). Two loci showed considerable association (-log₁₀P = 10.35 and 10.46) with LWA on chromosomes 5 and X, the MAF were 0.425 and 0.446, respectively. Seven loci were found to be associated with NBD. These loci are located on chromosomes 5, 6, 13, 14, 15, 16 and 18 (-log₁₀P = 10.95, 5.43, 8.29, 6.72, 6.81, 5.90, and 5.15, respectively). One locus showed association (-log₁₀P = 5.62) with M21D on chromosome 1 (the MAF was 0.461). Another locus was found to be associated with IBL on chromosome 8 (-log₁₀P = 7.56; the MAF was 0.438). The above-mentioned loci provide a straightforward possibility to assist selection by molecular tools and, consequently, to improve the competitiveness of the Hungarian Large White (HLW) breed.

X- and Y-chromosome-specific variants of the amelogenin gene allow non-invasive sex diagnosis for the detection of pseudohermaphrodite goats

The Polled Intersex Syndrome (PIS) is responsible for the absence of horns in homozygous and heterozygous goats causing a female-to-male sex reversal in the homozygous polled genotypic female (XX) goats. A simple and efficient non-invasive method was elaborated to detect the genotypic sex from hair and faecal samples using a pair of primers to amplify the X- and Y-linked alleles of the amelogenin gene. The PCR products were easily distinguishable using agarose gel electrophoresis: we detected an X-specific single band in samples originating from healthy phenotypic females and double (X- and Y-) bands in samples from males. The new PCR method is applicable for diagnosing the sex of PIS-affected animals already as newborn kids, in contrast with the phenotypic findings appearing only after puberty, and thus it may replace the cumbersome chromosome investigations.

Leukemia inhibitory factor promotes porcine oocyte maturation and is accompanied by activation of signal transducer and activator of transcription 3

We produced recombinant porcine leukemia inhibitory factor (pLIF) and examined its effect on in vitro maturation (IVM) of porcine oocytes and their developmental competence after in vitro fertilization. Porcine cumulus-oocyte complexes (COCs) were matured in a medium supplemented with pLIF during the first 22 hr, last 22 hr, or entire 44 hr duration of IVM. Oocytes in all groups tended to show enhanced nuclear maturation rates by the metaphase II (MII) stage (76.1%, 82.1%, and 86.6%, respectively) compared to the without-pLIF treatment group (69.6%, control). A significant increase in MII rate (P < 0.05) and obvious induction of cumulus expansion were observed over the whole time span (44 hr) in the IVM group. When cumulus cells were removed at 22 hr and denuded oocytes were further cultured, pLIF showed no effect on maturation rate. Oocytes matured in pLIF-supplemented medium showed a tendency for more rapid blastocyst development (21.1% vs. 16.2%, P = 0.0715). Examination of transcripts and proteins of the LIF signaling pathway in COCs revealed that LIF, LIF receptors, and signal transducer and activator of transcription 3 (STAT3) are present in both cumulus cells and oocytes. The amount of phosphorylated STAT3 (p-STAT3) markedly increased in both cumulus cells and oocytes cultured in pLIF-supplemented media, although oocyte p-STAT3 disappeared after 44 hr of IVM. These results suggest that the LIF/STAT3 pathway is functional during IVM of porcine oocytes, and supplementing pLIF in the IVM medium can improve oocyte maturation by activating this pathway.

Production of identical mouse twins and a triplet with predicted gender

The aim of this study was to develop a method to generate identical twins and triplets with predicted gender. As a first step toward that aim, single blastomeres obtained from EGFP expressing eight-cell stage embryos and either diploid or tetraploid host embryos were used to compose chimera. We could follow the fate of EGFP expressing diploid blastomere derived cells in 3.5- and 4.5-day-old chimera embryos in vitro. We found that the diploid blastomere-derived cells had significantly higher chance to contribute to the inner cell mass if tetraploid host embryos were applied. After that, we developed a quick and reliable multiplex PCR strategy for sex diagnosis from single blastomeres by simultaneous amplification of the homologous ZFX and ZFY genes. By composed chimeras using single blastomeres, derived from sexed eight-cell stage embryos and a tetraploid host embryo, we could get preplanned sex newborns, wholly derived from these blastomeres. Among these mice, identical twins and a triplet were identified by microsatellite analysis. Unlike clones produced by nuclear transfer, these mice are identical at both the nuclear as well as mitochondrial DNA level. Therefore, the tetraploid embryo complementation method to produce monozygotic twins and triplets could be a valuable tool both in biomedical and agricultural applications.

Experiences in deer sperm cryopreservation under practical conditions—A pilot study

The genetic potential of the red and fallow deer populations in Hungary is well known. Conserving the variability in this excellent genetic material for game preservation is one of our most important task. The aim of the present pilot study was to test the logistical steps of a sperm processing and storing system in which deer sperm can be stored at a level that meets quality standards accepted for domestic animals. Moreover, two different semen extenders, commercially used for freezing bull semen, were compared from the viewpoint of applicability to freeze fallow deer sperm. Sperm was collected from epididymes of eight red stags (Cervus elaphus hippelaphus) and six fallow bucks (Dama dama) during the rutting season. Red deer samples were washed in Triladyl extender, while fallow deer samples were split and processed in Triladyl or Bioxcell extender. In the samples, which had a shorter time interval between the death of the animal and the sperm collection, the percentage of viable spermatozoa with intact acrosome was typically higher.

Production of transgenic chimeric rabbits and transmission of the transgene through the germline

Here we report that improved reproductive technologies combined with an efficient microinjection method and in vitro cultivation medium enabled us to create germ line chimeric rabbits. To follow the fate of the chimeric embryo a blastomere marked with the human blood coagulation factor VIII (hFVIII) transgene was microinjected into a morula stage wild type embryo. The degree of chimerism in different tissues was estimated by real-time PCR and was found to be in the range of 0.1-42%. Among the four chimeric animals, one was identified as a chromosomal intersex and two were germline chimeras.

A simplified biopsy method for precompacted mouse embryos: a technical report

This article presents a new, simple and rapid embryo biopsy method. The blastomere for genetic analysis can be separated from a precompacted mouse embryo after a partial zona digestion with the use of a holding pipette. For the micromanipulation only two microcapillaries and micromanipulators are needed. The development of the biopsied embryos was studied during in vitro culture and in utero following embryo transfer. There was no significant difference between the treated and the control groups in the ratio of embryos that developed to the blastocyst stage, although the biopsied embryos were delayed in their development because they contained significantly fewer cells compared to the control ones at the same stage. Although there was no difference in the ratio of implantation, the development of the biopsied embryos in utero was also delayed 12-24 hours on the 9th day of pregnancy. No difference in development was visible from the 13th day of pregnancy. Statistically, no differences were found in the developmental ratio (number of developed fetuses/transferred embryos) of the control and treated embryos during gastrulation (9th day of pregnancy), at the beginning of organogenesis (13th day of pregnancy) and before birth (19th day of pregnancy). The embryo biopsy method presented here can be a new and useful tool for preimplantation genetic diagnosis.

Effect of swim up and Percoll treatment on viability and acrosome integrity of frozen-thawed bull spermatozoa

The aim of this study was to investigate the effect of the swim up and Percoll methods to select frozen-thawed bull spermatozoa with high quality membrane and acrosomal integrity and final concentration. Semen samples from six Holstein-Friesian bulls were examined. The whole experiment was repeated three times. Before and after both treatments, spermatozoa were subjected to a double-staining method and evaluated by brightfield light microscope using 40x dry, or 100x oil immersion objectives. The concentration of spermatozoa evaluated by haemocytometer was 8.8 x 10(7)/ml after thawing, and the percentage of live cells with intact acrosome was 45.8%. Both treatments significantly increased the proportion of live spermatozoa compared with no treatment, and the use of Percoll gradient resulted in a significantly higher percentage of living cells with an intact acrosome (88.2%) than the swim up method (69.4%). The concentration of spermatozoa after Percoll separation (9.3 x 10(6)/ml) was higher than that after the swim up method (5.8 x 10(6)/ml). These results indicate that spermatozoa with a higher viability and acrosome integrity can be obtained by Percoll separation than by the swim up method. Therefore the use of Percoll-treated spermatozoa in IVF systems can be more expedient.

Preimplantation genetic diagnosis in cattle: a review

Preimplantation Genetic Diagnosis (PGD) is reviewed and novel fields where it may be applied are investigated. Technical advances of PGD in cattle embryos have already enabled its integration as a part of the MOET (Multiple Ovulation Embryo Transfer) breeding system. PGD for well-defined selection targets can enhance cattle breeding and embryo trade. It allows embryo selection according to their sex, and it may be used to breed special cow lines, or top bulls, by selecting embryos for valuable production traits using Marker Assisted Selection (MAS). A good allelic profile and/or the insertion of a transgene can be detected by PGD. This review article presents the technical requirements for PGD, and shows that this biotechnological method has great economic potential.

Comparison of different treatments for parthenogenetic activation of bovine oocytes matured in vitro

In vitro matured bovine oocytes were treated by three parthenogenetic activation methods. Basic treatment with Ca-ionophore and cytochalasin D was combined with cycloheximide (Group 2), electric impulse (Group 3), and cycloheximide and electric pulse (Group 1) treatments, respectively. Survival and the in vitro development of parthenogenetic embryos to hatched blastocyst stage were compared. Rates of the first cleavage and morula development significantly differed among the treatment groups. Further development rates of the treated embryos up to blastocyst stage did not differ. The best results were obtained by the combination of cycloheximide and electric treatments (Group 1; 14% blastocyst, 7% hatched blastocyst). The results suggest that the combined treatment for oocyte activation is the most efficient and should be applied for cloning procedures.