Screening for polymorphism at the prion protein (PrP) locus (PRNP) in Awassi and Assaf populations in Israel, the Palestinian Authority and Jordan

Screening for polymorphism at the prion protein (PrP) locus (PRNP) was carried out in 33 flocks of Local Awassi (LA) sheep in Israel, the Palestinian Authority (PA) and Jordan. In addition, PRNP genotyping was carried out in two flocks of Improved Awassi (IA) in Israel and the PA and in 11 flocks of Assaf sheep in Israel. Most of the rams present in the flocks at the time of the survey 328, 44 and 298 rams from the LA, IA and Assaf breeds, respectively, were genotyped. The ARQ allele was found to be predominant in all three breeds with average frequencies of 0.74, 0.78 and 0.86 for the LA, IA and Assaf breeds, respectively. Frequencies of the desirable ARR allele in these breeds were 0.10, 0.05 and 0.06, respectively. ARH, AHQ and ARK alleles were identified at low/absent frequencies. Only one Assaf ewe carried the undesirable V allele at codon 136. A few scrapie outbreaks have been documented in the past in the region. To increase ARR allele frequencies in the Awassi and Assaf populations, distribution of homozygous ARR/ARR rams is recommended.     

Sperm output and hormone concentrations in Finn and Dorset rams exposed to long- and short-day lighting

Seasonal changes in photoperiod have a substantial effect on sexual behavior and reproduction in rams. Little information is available on sperm output from high libido versus average libido rams subjected to intensive semen collection while being exposed to controlled short versus long photoperiods. Six Finn and six Dorset rams were compared in a reversal design, which allowed rams of both breeds to be exposed to 8 h versus 16 h of light. During each of two 84-d periods rams were subjected twice to an initial depletion of epididymal sperm reserves by collecting up to 26 ejaculates of semen in 3 d, followed by up to 10 ejaculates per day, 1, 3, 5, and 7 d after the initial depletion. A total of 2673 semen samples were collected. Nearly twice as many ejaculates (63.6% of the total) were obtained from Finn rams as from Dorset rams during both the initial and subsequent 3-d sperm depletion periods. This difference in libido was associated with obtaining 33.6 +/- 3.1 x 10(9) sperm from Finn rams versus 10.0 +/- 2.2 x 10(9) sperm from Dorset rams during the initial depletion period (P<0.05). Changes in photoperiod did not affect sperm output (P>0.05) in Finn rams, but may have affected Dorset rams. With 16 h of light, prolactin was significantly (P<0.05) increased in both breeds, particularly in Finn rams. Testosterone in both breeds followed an endogenous rhythm, not affected by the change in controlled photoperiods.     

Genetic diversity of the prion protein gene (<Emphasis Type="Italic">PRNP</Emphasis>) coding sequence in Czech sheep and evaluation of the national breeding programme for resistance to scrapie in the Czech Republic

Of 34 breeds kept in the Czech Republic 45,604 sheep were genotyped for codons 136, 154 and 171 in the prion protein gene (PRNP) during the years 2006–2014. In this cohort, haplotypes ARR, ARQ, ARH, AHQ, VRQ, AHR and ARK were detected. The haplotype AF₁₄₁RQ associated with susceptibility to atypical scrapie was observed in nine out of 30 breeds analysed for this purpose. In addition, six rare nonsynonymous substitutions producing haplotypes AT₁₃₇RQ, AN₁₃₈RQ, AG₁₅₁RQ, AH₁₅₁RQ, ARL₁₆₈Q and ARQE₁₇₅ were identified in various breeds. Due to their low frequencies, these polymorphisms are of no potential importance for the breeding programme. With regard to their genetic particularity, Sumavka, Valachian and Cameroon breeds were screened for additional polymorphisms. Further haplotypes, AR₁₄₃RQ and AS₁₄₆RQ, were found in Sumavka and Cameroon, and in Valachian sheep, respectively. Frequencies of the ARR (resistance-associated), VRQ (susceptibility-associated) haplotypes, and of the most resistant ARR/ARR genotype calculated for sheep born in the years 2001–2003 and 2011–2013 documented effects of the 10 year-lasting national breeding programme. The total frequency of ARR doubled from 36.8 to 75.8 %, while the frequency of VRQ decreased from 4 to 0.7 %. The total frequency of the ARR/ARR genotype increased from 17.7 to 59 %. These data show that the national scrapie resistance breeding programme has had an important desirable effect on haplotype and genotype frequencies of PRNP in Czech sheep.     

Fertility of undiluted ram epididymal spermatozoa stored for several days at 4°C

In vitro preservation of the male gamete is a challenge in the development of artificial insemination techniques for domestic animals. Specific strategies and diluents have been developed for the preservation of the fertilizing ability of the semen for each species. However, the epididymal medium has been demonstrated to be the best sperm environment to maintain sperm viability over several days and weeks for mammals. The aims of this study were to evaluate the motility and in vivo fertility of ram epididymal spermatozoa when the semen was stored for up to 4 days at 4°C undiluted in epididymal plasma. The study was undertaken with two ovine breeds (Ile de France and Corriedale). The motility of epididymal spermatozoa was better preserved in the undiluted epididymal fluid than when epididymal spermatozoa were diluted in classic ovine extender such as skim milk. During storage, the decrease in the percentage of motile sperm was lower if the epididymal spermatozoa were collected immediately after epididymal sampling than 24 h after castration or animal death. The fertility obtained after cryopreservation of the stored sperm and subsequent intrauterine insemination ranged from 55% to 24% following 24 to 96-h sperm storage. There was a linear regression relationship between fertility and the number of motile sperm inseminated for both breeds. These results show that it is possible to keep epididymal sperm motile and fertile for several days without dilution. Such a method of sperm preservation could be a final possibility for animals of high genetic value or for endangered species when the collection of semen before death of the animal is not possible.     

Testosterone secretion and semen plasma enzyme activity in rams with genital pathology stimulated with GnRH

Testosterone secretion in response to GnRH stimulation and enzymatic activity of semen plasma was evaluated comparatively in rams with or without genital abnormality. Scrota, testes and epididymides of 128 rams between 1.5 and 6 years old from various breeds were examined clinically and ultrasonographically. Bilaterally cryptorchid rams (n = 2), and rams with focal testicular degeneration (n = 3) or unilateral sperm granuloma localized in the caput (n = 3) epididymis or the cauda epididymis (n = 3), diagnosed by either clinical or ultrasonographic examination, were selected for the further investigation of spermatologic parameters, testosterone secretion in response to GnRH stimulation, and enzymatic activity of semen plasma before histopathologic confirmation of lesions. Except for the cryptorchid rams, sperm parameters determined in ejaculates were similar to intact controls (n = 3). GnRH administration increased plasma testosterone levels significantly irrespective of the type of genital pathology (P < 0.01). The testosterone response calculated based on area under the curve following GnRH administration in rams having genital abnormality was not significantly different from the controls. Aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) activity in the semen plasma varied between rams, with the lowest mean values in the bilaterally cryptorchid group (P < 0.05). Spermatic granuloma localized either in the caput or cauda of the epididymis was associated with a significant reduction in the semen plasma AST activity compared to controls (P < 0.01). In conclusion, our results indicated that the ability of testicular tissue to secrete testosterone in response to GnRH stimulation in rams with bilateral cryptorchidism, focal testicular degeneration and unilateral sperm granuloma was similar to that of intact controls, and that reduced semen plasma AST activity may have a diagnostic value in the diagnosis of the epididymal obstruction in rams. Focal testicular degeneration did not influence AST, alkaline phosphatase (ALP) and LDH activity in semen plasma.     

Quality and freezing qualities of first and second ejaculates collected from endangered Gulf Coast Native rams

The Gulf Coast Native sheep, or Louisiana Native sheep, is an endangered previously feral domestic sheep population of European origin that has been under natural selection pressure for reproductive survival in their transplanted range while roaming in the southern Gulf Coast Region of the United States. This sheep population has an increased natural resistance to internal parasites, breeds year-around and has a greater percentage of live lambs as compared with other breeds of sheep raised in similar environments. To preserve the genetic diversity of this important feral sheep population, semen was collected by electro-ejaculation and subjected to cryopreservation for subsequent storage in a genome resource bank. Unrelated rams (n=5) were collected 3 days-a-week, allowing at least 2 days of rest between collections. Two ejaculates were obtained from each ram per collection day, with the second collection conducted 10min after the first ejaculation. Semen was processed using the standard Salamon cryopreservation procedure in a Tris-yolk-glycerol extender, frozen in 0.5ml plastic straws using liquid nitrogen (LN(2)) vapor and stored in LN(2). Each ejaculate was evaluated for volume, sperm concentration/ml (x10(9)/ml), number of spermatozoa/ejaculate (x10(9)), sperm progressive motility (%) for pre-cooled semen, cooled semen and semen after thawing. For the five rams, each semen variable for the first ejaculate was compared with that of the second ejaculate collected 10min later. The mean semen volume, sperm concentration and number of spermatozoa per ejaculate obtained from the first ejaculate were significantly greater (P< or =0.01) than those of the second ejaculate (comparisons being 1.62 and 1.06; 3.2 and 1.5; 5.4 and 1.8, respectively). Overall, the mean motility of pre-cooled (22 degrees Celsius), cooled (5 degrees Celsius) and frozen (-196 degrees Celsius) post-thawed spermatozoa was less (P< or =0.01) in the first ejaculate (71.5, 64.8 and 34.1%, respectively) compared with that of the second ejaculate (75, 72.4 and 44.1%, respectively). Conversely, no differences were detected in loss in the percent progressive motility of sperm from cooled sperm to post-thaw sperm from the first and second ejaculates. In summary, our findings suggest sperm collected during the second ejaculate 10min after the first ejaculate of rams survives thawing with a greater rate of progressive motility than that of the first ejaculate. The ability to collect two consecutive ejaculates in a short period by electro-ejaculation could be valuable for gamete resource banking and preserving genetic diversity of the Gulf Coast Native sheep.     

Review: A review on classical and atypical scrapie in caprine: Prion protein gene polymorphisms and their role in the disease

Scrapie is a naturally occurring transmissible spongiform encephalopathy in sheep and goat. It has been known for ~250 years and is characterised by the accumulation of an abnormal isoform of a host-encoded prion protein that leads to progressive neurodegeneration and death. Scrapie is recognised in two forms, classical and atypical scrapie. The susceptibility to both types of scrapie is influenced by polymorphisms of the prion protein gene (PRNP). Sheep susceptibility or resistance to classical scrapie is strongly regulated by the polymorphisms at codons 136, 154 and 171 of the PRNP. The genetic role in atypical scrapie in sheep has been defined by polymorphisms at codons 141, 154 and 171, which are associated with different degrees of risk in the occurrence of the ovine disease. Progress has been achieved in the prevention of scrapie in sheep due to efficient genetic breeding programmes based on eradication and control of the disease. In Europe, the success of these programmes has been verified by applying eradication and genetic selection plans. In general terms, the ovine selection plans aim to eliminate and reduce the susceptible allele and to enrich the resistant allele ARR. During outbreaks all susceptible animals are slaughtered, only ARR/ARR resistant rams and sheep and semi-resistant females are preserved. In the occurrence of scrapie positive goats a complete cull of the flock (stamping out) is performed with great economic loss and severe risk of extinction for the endangered breeds. The ability to select scrapie-resistant animals allows to define new breeding strategies aimed to boost genetic progress while reducing costs during scrapie outbreaks. Allelic variants of PRNP can be protective for caprine scrapie, and the knowledge of their distribution in goats has become very important. Over the past few years, the integration of genetic information on goat populations could be used to make selection decisions, commonly referred to as genetic selection. The objective of this review was to summarise the main findings of polymorphisms of the caprine prion protein (PrP) gene and to discuss the possible application of goat breeding schemes integrating genetic selection, with their relative advantages and limitations.     

Cryopreservation of epididymal stallion sperm

Any event that makes semen collection or mating impossible, such as death, castration, or injury, may terminate a stallion’s breeding career. Fortunately, stallion sperm which are capable of fertilization can be harvested from the epididymis, and frozen for future use. However, the fertility of frozen–thawed epididymal sperm has been found to be lower than that of ejaculated sperm. Therefore, this study aimed to optimize the fertility of frozen epididymal stallion sperm by investigating the effects of different cryoprotectants and freezing protocols on sperm quality. Dimethylformamide was tested alone or combination with pasteurized egg yolk as substitute of fresh egg yolk. In addition, the effect of the pre-freeze stabilization on sperm quality was analyzed. Heterospermic samples obtained from stallion epididymis were collected and cryopreserved in lactose–egg-yolk extender or in the same extender with varying content of cryoprotectant and content of egg yolk, stabilized and no-stabilized. Sperm motility, viability, hypoosmotic swelling test (HOST) and acrosome integrity were evaluated post-thawing. No improvement was observed on the replacement of fresh yolk by pasteurized egg yolk, whereas the results suggest that dimethylformamide is a cryoprotectant suitable for cryopreservation of equine epididymal semen, even better than glycerol. In addition, we found that the stabilization before freezing on epididymal stallion sperm, can improve sperm quality parameters.     

An assessment of sperm motility estimation for evaluation in rams

There is disagreement about the value of estimating spermatozoal motility as a predictor of fertility in rams. We tested the hypothesis that sperm motility can help one to predict lambing rate by evaluating sperm motility in rams prior to breeding and by subsequently breeding the rams regardless of their sperm motility results. A total of 943 rams (Merino, n=630 and Romney Marsh, n=313) was used during two breeding seasons. For fertility evaluation only 804 rams that bred at least ten ewes each were included in the study. Rams were grouped into 4 groups according to sperm motility scores, ranging from the lowest, which included rams with azoospermia, oligospermia, non-motile and single-motile sperm, through rams with 10 to 30%, 30 to 60%, to the highest at 60 to 100% motile sperm. The corresponding fertility rates found in our study in Merino and Romney breeds were 58.3 and 47.4%, 75.1 and 59.1%, 79.4 and 64.1% and 81.5 and 64.0%, respectively. We concluded that there was a statistically confirmed difference in fertility between the lowest and all the other motility categories. The differences in fertility among rams that had motility categories above 10% were not statistically significant. Evaluation of breeding soundness in large scale surveys of rams, based on sperm motility estimation, may be misleading. Clinical examination of genital organs seems to offer a reliable source of information about rams, and may be considered adequate in sheep breeding.     

Comparison of equilibration times when freezing epididymal sperm from African buffalo (Syncerus caffer) using Triladyl or AndroMed

Because of risks of disease transmission, it is not possible to move African buffalo (Syncerus caffer) within South Africa. Therefore, new ways must be found to enable exchange of genetic material and to increase genetic diversity. In this study epididymal sperm from 11 African buffaloes was exposed to 8 different pre-freezing equilibration times, using 2 different semen extenders. To test the influence of equilibration time and to find a practical way of freezing sperm in the field equilibration times between 2 and 9 h were compared. The extenders used were Triladyl and the totally defined extender AndroMed (both Minitüb, Tiefenbach, Germany). Post-thaw motility, longevity and acrosomal integrity were compared. Different equilibration times did not result in different post-thaw qualities. The use of Triladyl resulted almost always in higher post-thaw motilities and in better acrosomal integrity. Individual bulls had a significant influence on measured parameters. Results indicate that sperm flushed in the field can be stored in freezing medium for up to 9 h before being further processed and that Triladyl is superior to AndroMed when freezing epididymal African buffalo sperm. This knowledge is important to plan fieldwork, since working conditions are usually far from the ideal of a laboratory.     

Sperm motion characteristics of GarolexMalpura sheep evolved in a semi-arid tropical environment through introgression of FecB gene

The arid and semi-arid tropical climates of India are endowed with vast diversity of non-prolific sheep breeds. The GarolexMalpura sheep has been evolved in a semi-arid tropical environment by introgression of FecB gene via artificial insemination of Malpura ewes using diluted semen of prolific microsheep Garole and subsequently multiplied by inter se mating among GarolexMalpura halfbreds. The aim of the present study was to identify FecB mutation in sexually mature GarolexMalpura rams by forced RFLP-PCR of BMPR-1B gene and evaluate: (i) semen production and sperm motion characteristics of GM rams and (ii) influence of age and FecB genotype on their semen attributes. Semen was collected during autumn season from 12 donor rams by artificial vagina on 8 occasions at weekly interval. The overall means of traits which did not differed significantly with age or FecB genotyping were volume (0.72 ml), mass motility (4.44), sperm concentration (2721.56 x 10(6)ml(-1)), curvilinear velocity (134.51 microm/s), motility (81.3%), amplitude of lateral head displacement (6.24 microm), beat frequency (44.43 Hz), sperm head elongation (48.9%) and sperm head area (10.01 microm(2)). The FecB genotyping had a significant effect (P<0.05) on percent linearity and rapid motile sperms, which did not vary significantly with age. Although sperm concentration was higher in FecB(BB) and FecB(B+), compared to FecB(++) genotypes but the effect was non-significant. The age and FecB genotyping had significant effects (P<0.05) on straightness, average path velocity, straight-line velocity and percentage of medium or slow motile sperms. It is concluded that GarolexMalpura rams with introgressed FecB gene are capable of producing good quality semen in a semi-arid tropical climate.     

Predicting the consequences of selecting on PrP genotypes on PrP frequencies,performance and inbreeding in commercial meat sheep populations

Selection programmes based on prion protein (PrP) genotypes are being implemented for increasing resistance to scrapie. Commercial meat sheep populations participating in sire-referencing schemes were simulated to investigate the effect of selection on PrP genotypes on ARR and VRQ allele frequencies, inbreeding and genetic gain in a performance trait under selection. PrP selection strategies modelled included selection against the VRQ allele and in favour of the ARR allele. Assuming realistic initial PrP frequencies, selection against the VRQ allele had a minimal impact on performance and inbreeding. However, when selection was also in favour of the ARR allele and the frequency of this allele was relatively low, there was a loss of up to three to four years of genetic gain over the 15 years of selection. Most loss in gain occurred during the first five years. In general, the rate of inbreeding was reduced when applying PrP selection. Since animals were first selected on their PrP genotype before being selected on the performance trait, the intensity of selection on performance was weaker under PrP selection (compared with no PrP selection). Eradication of the VRQ allele or fixation of the ARR allele within 15 years of selection was possible only with PrP selection targeting all breeding animals.     

Artificial insemination in canids: a useful tool in breeding and conservation

Artificial insemination (AI) and semen freezing have become services available to dog owners worldwide, and the demand for services to freeze semen is increasing. In other canids such as the fox, the fur industry utilizes fresh or frozen semen to artificially inseminate vixens to produce pelts. Clearly, AI facilitates the use of a male to sire several females by diluting the ejaculate, increases breeding hygiene, and allows crossing between species with slightly different breeding seasons. The African wild dog (Lycaon pictus) is currently considered by the World Conservation Union (IUCN) as one of most endangered canids. In captive populations of African wild dogs, semen has been frozen with encouraging results, using a standard cryopreservation protocol for domestic dogs, but successful AI has not been reported. In wolves, there is one report regarding the live birth of an offspring after intravaginal AI of a deslorelin-induced estrous female. In 2005, three Mexican gray wolf females were artificially bred by intrauterine insemination with freshly collected semen from unrelated males, and all females whelped. Artificial insemination may be vaginal, intrauterine or intratubal, and the semen may be fresh, fresh and chilled (diluted), or frozen-thawed, and the source of semen may be epididymal or ejaculated. In the domestic dog, the results are good to excellent for AI with all three types of processed semen when the source is ejaculated semen, whereas epididymal sperm still yields poorer results. Species differences in female physiology, as well as differences in the cryotolerance of the sperm from various canid species, warrant further research and development.     

Alpha-1,4-glucosidase activity in ram seminal plasma is inversely related to serum testosterone

The epididymis of adult rams is the primary source of alpha-glucosidase in seminal plasma. Two breeds of rams were selected to ascertain whether the enzyme was under androgenic control during adult life of rams. Opposite variations between serum testosterone and alpha-glucosidase were recorded over a period of 16 months in Suffolk and Finnish Landrace. In addition, the highest percentage of sperm motility was associated with a low alpha-glucosidase content of seminal plasma. Data from this study suggest that seasonal variations of testosterone in adult rams exert a negative control on the presence of alpha-glucosidase in semen.     

Freezability of spermatozoa from Finn and Dorset rams in multiple semen extenders

Ten semen extenders were tested in two experiments for cryopreservation of semen collected from four Finn and four Dorset rams. Two ejaculates of semen were combined from each ram for testing each extender treatment. The extenders consisted of a series of commonly used egg yolk-TRIS media with and without sodium and triethanolamine lauryl sulfate (STLS), a similar extender with 3-N-morpholino propane sulfonic acid (MOPS), and milk and whey extenders. In Experiment 1, extender treatments were replicated with three sets of collections from the eight rams, and in Experiment 2 with two sets. The egg yolk-TRIS-glycerol-STLS (EY(1)TSTLS) extender was significantly superior to other extenders except whole milk in protecting the sperm during freezing and thawing. In Experiment 1, a 20% egg yolk-TRIS-glycerol-STLS extender preserved 71% of the progressively motile Finn sperm (post-thaw divided by pre-freeze percentage of motile sperm), and 76% of the Dorset sperm. In Experiment 2, the corresponding values for the same EY(1)TSTLS extender used with Finn and Dorset sperm were 86 and 64%, respectively. Without STLS the egg yolk extenders were significantly less effective in protecting cryopreserved ram sperm. This egg yolk-TRIS extender, containing STLS and glycerol, may hold promise for freezing ram sperm that could be used successfully for intracervical insemination.     

Quantification of the X- and Y-chromosome-bearing spermatozoa of domestic animals by flow cytometry

The relative content of DNA in spermatozoa presumed to be the X- and Y-chromosome-bearing gametes from bulls, boars, rams and rabbits and the amount of DNA in spermatozoa of cockerels was determined by flow cytometry. Differences in the relative content of DNA and proportions of the presumed X- and Y-sperm populations in cryopreserved semen from Holstein, Jersey, Angus, Hereford and Brahman bulls were also determined. Spermatozoa were washed by centrifugation using a series of dimethyl sulfoxide solutions made in isotonic sodium citrate, fixed in ethanol, treated with papain and dithioerythritol to loosen the chromatin structure and remove cellular organelles, and stained quantitatively for DNA with the fluorochrome 4'-6-diamidino-2-phenylindole (DAPI). Approximately 5000 stained sperm nuclei, which were nonviable due to the removal of other cellular organelles during the washing procedure, were measured for DNA in an epi-illumination flow cytometer. A single distinct peak for cockerel spermatozoa and two symmetrical, overlapping peaks for species with X- and Y-spermatozoa were seen. This and other evidence strongly supports the interpretation that the peaks represent the X- and Y-sperm populations. The content of DNA in sperm nuclei from cockerels, bulls, boars, rams and rabbits, as determined by fluorescence flow cytometry, corresponded to biochemical estimates of DNA per sperm cell. Analyses of the bimodal histograms by computer-fitting two Gaussian distributions to the data showed the means of the peaks differed by 3.9, 3.7, 4.1 and 3.9% for bulls, boars, rams and rabbits, respectively. In four replicate analyses of semen from 25 bulls representing 5 breeds, the average population of sperm nuclei in the Y-peaks ranged from 49.5 to 50.5% for all breeds. The X-Y peak differences did not vary within each breed, but were significantly different when the breeds were compared. Spermatozoa from Jersey bulls had larger X-Y peak differences (P less than 0.001) than spermatozoa from Holstein, Hereford, and Angus bulls; spermatozoa from Brahman bulls had smaller X-Y differences (P less than 0.004). It is suggested from the evidence obtained in these studies that flow cytometry can be used to assess the proportion of X- and Y-spermatozoa in semen of domestic animals and is thereby applicable to verification of the effectiveness of enrichment techniques for X- or Y-spermatozoa.     

In vitro fertilization of porcine oocytes with fresh and frozen-thawed ejaculated or frozen-thawed epididymal semen obtained from identical boars

The objective of this study was to compare the in vitro fertilizing capacity of porcine spermatozoa from fresh and frozen-thawed semen and frozen-thawed epididymal spermatozoa obtained from identical boars. Prior to IVF, fresh spermatozoa were capacitated in TCM 199. Frozen semen samples were stored in 0.25-ml plastic straws using a lactose/glycerol/orvus-es-paste extender. Cumulus-oocyte-complexes (COC) obtained from superovulated prepuberal gilts were fertilized in vitro within 2 h after aspiration with one of the semen samples. After final dilution for IVF, frozen-thawed epididymal semen samples showed motility rates (72.2 +/- 5.6%) similar to those of spermatozoa in fresh semen (76.4 +/- 4.5%), while sperm motility decreased in frozen-thawed ejaculated semen (40.2 +/- 9.4%). Considerable individual differences in sperm motility between boars were observed for ejaculated semen but not for epididymal semen. Enhanced fertilizing capacity of frozen-thawed epididymal spermatozoa was confirmed by pronucleus formation and cleavage rates, with significantly more embryos developing to the 2- and 4-cell stages compared with the groups fertilized with fresh or with frozen-thawed ejaculated semen (59.7 vs 14.6 and 16%). In conclusion, consistent in vitro fertilization rates with minimal semen variability are obtained using frozen-thawed epididymal semen. Following a modified freezing protocol, epididymal spermatozoa can easily be frozen in small containers for IVF, with higher resultant motility and fertilization rates than with ejaculated semen.     

Seasonal thyroidal activity and reproductive characteristics of Iranian fat-tailed rams

An experiment was conducted to study seasonal variations of thyroidal activity, serum testosterone concentration and seminal characteristics of two breeds of Iranian fat-tailed sheep. Eight 3 to 4-year-old rams of Ghezel and Mehraban breeds (4 rams/breed) were randomly selected from a flock of fertile rams. Semen was collected by using an artificial vagina, and blood samples were obtained via jugular vein. Seminal characteristics, scrotal length, width, and circumference, and blood parameters were measured at 3-week intervals. Time of the year significantly (P < 0.05) affected the volume of semen, sperm concentration, percent live sperm, percent normal sperm, total sperm number, seminal pH, seminal lactate dehydrogenase (LDH) concentration, scrotal circumference, scrotal width, and serum levels of testosterone, cholesterol, triiodothyronine (T(3)), tetraiodothyronine (T(4)), free T(4) index (FT(4)I), and TSH. Scrotal length was not affected by the time of sampling (P > 0.05). The effect of breed on the serum concentrations of hormones and cholesterol was not significant. Volume of semen, percent normal sperm, and total number of normal sperm were significantly (P < 0.05) higher in Mehraban but scrotal circumference, scrotal width and scrotal length were greater in Ghezel rams. Breedxtime interaction effect was significant for T(4), FT(4)I, sperm concentration, and total sperm number. The largest values for TSH, T(4), FT(4)I, testosterone, total sperm number, percent normal sperm, percent live sperm, sperm concentration, volume of semen and scrotal circumference were found from early summer to winter and the lowest values were recorded at the end of spring and in early summer. In both breeds, high and negative correlations (r = -0.7 to -0.8) were found between LDH levels in semen and percent live sperm, percent normal sperm and total sperm number (P < 0.01). It is unlikely that such variations in seminal quality would affect the fertility under natural mating.     

Semen characteristics of Ile-de-France rams of different age and physical condition

A breeding soundness examination (BSE) involving animal physical examination, scrotal circumference (SC) and semen evaluation was undertaken on 80 Ile-de-France rams at a government breeding farm, 32 km south-west of Casablanca (Morocco) from March to May 1988. A large percentage of rams (21.4%) was found to be unfit for breeding due to physical and genital abnormalities; 11 and 5% had disorders of the feet and respiratory system; upon genital palpation, 17.5, 13.8 and 7.5% of animals had orchitis, epididymitis and posthitis, respectively. The SC increased with age from 28.8+/-3.2 cm at 相似文献   

Evaluation of the present breeding programme against copper toxicosis in Danish Bedlington terriers

A breeding programme to eradicate copper toxicosis in Danish Bedlington terriers has been established based on a DNA marker test. Genotyping of both parents is compulsory and after 1 January 2000, only homozygous non-carriers are used for breeding. In this study, two groups of Bedlington terriers were genotyped at 18 microsatellite loci. One group represented the original population of Bedlington terriers before introducing the breeding programme (n = 23); the other represented a group of homozygous non-carriers (n = 24) available for breeding after year 2000. Allele numbers, allele frequencies, observed heterozygosities (Ho), expected heterozygosities (He), locus-specific coefficients of inbreeding (Fl) and Nei's genetic distance (D) was calculated. Individual coefficients of inbreeding (Fi) were calculated from the pedigrees and an assignment test was performed. Four rare alleles were lost in the group of homozygous non-carriers. No significant differences were observed between the mean values of allele numbers, Ho, He, Fl and Fi of the two populations of dogs. Nei's genetic distance between the two populations was 0.06 and 88% of the homozygous non-carriers were assigned correctly in the assignment test. The overall diversity of the breed was low (Ho = 0.41) and the breeders were advised to include the heterozygous carriers again.