Hygienic aspects of storage and use of semen for artificial insemination

The artificial insemination (AI) industry has developed over the last 50 years to the extent that it is used in almost every country in the world. One of the main factors contributing to its success is the confidence of the farmers that germplasm is not associated with pathogens, so that AI can be performed without risks. This has been achieved as a result of a considerable amount of research based on sound scientific data that has identified the major risk pathogens. A summary of these studies, given in this section, shows that despite the large number of agents that could be transmitted via the semen, there are cost-effective means to prevent such hazards. One of the basic rules is that the males should be housed in strictly protected semen collection centres (SCCs). Such centres should be approved by the veterinary authorities based upon specific criteria, which include special housing and operating specifications. This also includes specific means of monitoring the health of individual males through regular clinical examinations, assessment of semen and testings for various diseases. Two new challenges can now be identified, one relevant to so-called emerging diseases the impact of which on the status of the semen donors should always be assessed, and the second, relates to endangered genetic resources which may become extinct without active conservation programmes. The experience gained by the AI industry over the last 50 years should help to solve those problems. Currently, the use of semen derived from approved SCCs warrants their disease-free status.

Pregnancy-specific protein B, progesterone concentrations and embryonic mortality during early pregnancy in dairy cows

Pregnancy-specific protein B (PSPB) and progesterone concentrations were determined by RIAs in venous plasma during early pregnancy after 177 artificial inseminations (AI) performed in 76 cows and 71 heifers. The females were bled at 24, 26, 30-35 days and approximately 70 days (for non-returns to oestrus) after AI. In non-pregnant females without extended CL maintenance (progesterone less than 1.5 ng/ml on Day 24) and or showing a normal time of return to oestrus (Group 1, N = 63), PSPB concentrations were undetectable whatever the stage after AI except in 2 cows. In pregnant animals (N = 83; Group 2) progesterone concentrations were greater than 10 ng/ml from Day 24 to the time of rectal palpation and PSPB concentrations rose continuously from 0.42 +/- 0.07 (s.e.m.) ng/ml (Day 24) to 4.06 +/- 0.3 ng/ml (time of rectal palpation). No coefficient of correlation between PSPB and progesterone concentrations was significant whatever the day of gestation studied. In cows with extended luteal function and subsequently found to be non-pregnant (late embryonic mortality) PSPB was undetectable (N = 21; Group 3) or detectable (N = 10; Group 4) at Days 24, 26 and/or 30-35 of pregnancy. At 24 and 26 days after AI progesterone concentrations were intermediate between those of Groups 1 and 2. At Day 24 females of Group 4 had higher progesterone concentrations than those of Group 3 (P less than 0.05), but no differences between these two groups existed at subsequent stages after AI.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of bull semen fertility by homologous in vitro fertilization tests

In vitro fertilization assays were performed to investigate their validity in evaluating artificial insemination (AI) bull fertility. A total of 1,532 oocytes, collected from ovaries at the abattoir, were subsequently used in a 4 x 6 x 2 factorial design: 4 doses of heparin added into the capacitation and fertilization medium (0; 0.05; 0.1 and 0.2 micrograms/ml), 6 different bulls with known on-field non-return (NR) rates (range: 64.6-75.3%) and 2 different ejaculates for each bull, collected within a approximately 1-month interval. Oocytes were considered fertilized when 2 pronuclei (or more) were seen in the ooplasm. Both the heparin dose and bull exerted a highly significant effect on the in vitro fertilization (IVF) rates which ranged, per oocyte group, from 30-80%; bull x dose of heparin interaction was significant (P less than 0.001). The 0.05 micrograms/ml dose of heparin was optimal for discriminating individual bulls. At that dose, the correlation coefficients between the bulls, NR rates and the IVF rates from each ejaculate (within-bull or the mean of two ejaculates), were highly significant (r = 0.83). The rates of polyspermy were also significantly influenced by bull and heparin dose, but there was no interaction. In conclusion, capacitation and fertilization in a modified Tyrode medium containing 0.05 micrograms/ml of heparin may be a valuable tool for evaluating AI bull fertility.

Influence of postpartum energy restriction on energy status, plasma LH and oestradiol secretion and follicular development in suckled beef cows

Effects of postpartum energy restriction, parity and time after parturition on energy status (measured by glucose, insulin, non-esterified fatty acids (NEFAs) and beta-hydroxybutyrate), LH secretion and follicular growth were investigated in ten primiparous and nine multiparous suckled cows. Females were allocated by parity, body mass and body condition score at calving to diets supplying either 100% (CE, n = 10) or 70% (LE, n = 9) of energy requirements until day 70 postpartum. Metabolic parameters were measured every week from calving to day 70 postpartum. Blood samples were collected at intervals of 15 min for 10 h on day 30 and day 50 after parturition for LH measurement. Ovaries were examined between days 20 and 30 and days 40 and 50 postpartum by ultrasonography. Energy supply affected mean plasma concentrations of glucose (CE: 0.64 +/- 0.01 g l-1 versus LE: 0.61 +/- 0.01 g l-1; P < 0.05) and NEFA (CE: 168 +/- 17 mu eq l-1 versus LE: 309 +/- 18 mu eq l-1; P < 0.01) but by day 70 postpartum, glucose and NEFA concentrations were not significantly different between the two groups. LH pulse amplitude and frequency were not affected by energy supply (P > 0.10). However, at day 30 postpartum, LH pulse frequency was negatively correlated with plasma concentration of NEFA (r = -0.61; P < 0.01). Cows fed diets supplying 100% of energy requirements had more large follicles than did cows fed low energy diets (CE: 0.82 +/- 0.05 versus LE: 0.31 +/- 0.05; P < 0.05). The size of the largest follicle was greater in CE cows than in LE cows (CE: 10.2 +/- 0.1 mm versus LE: 8.7 +/- 0.2 mm; P < 0.05). Between 40 and 50 days postpartum, the size of the largest follicle was negatively correlated with NEFA concentration (r = -0.5; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Pregnancy-specific protein B and progesterone concentrations in French Alpine goats throughout gestation

The 34 French Alpine dairy goats originated from a single flock and were artificially inseminated 44 h after synchronization of oestrus. They were bled daily at the jugular vein from 15 to 27 days after AI. An early pregnancy diagnosis by RIA of progesterone concentration was performed 21 days after AI. In pregnant goats (greater than 1.5 ng progesterone/ml) daily sampling was extended until 30 days after AI and, from those, 9 were bled every 2 weeks until the end of pregnancy and at 50 and 63 days post partum. Pregnancy-specific protein B (PSPB) was also assayed. The kidding rate was 67.6% (23/34). PSPB concentrations (ng/ml) in pregnant goats were significantly different from those of non-pregnant goats at 24 days after AI (0.82 +/- 0.18 vs 1.78 +/- 0.19; mean +/- s.e.m.) and rose to 40 ng/ml at the end of pregnancy. From Day 25 and throughout gestation, females with 2 fetuses had higher PSPB concentrations than did those with a single fetus (P less than 0.05). In the 2 goats exhibiting late embryonic mortality according to progesterone concentrations, one had a PSPB profile very similar to those of pregnant goats until 30 days while the other did not show any elevation of PSPB concentration. It is concluded that PSPB profiles in goats are similar to those found in cows throughout pregnancy and that PSPB RIA may be useful for pregnancy diagnosis or diagnosis of late embryonic mortality.

Diagnosis of pregnancy by radioimmunoassay of a pregnancy-specific protein in the plasma of dairy cows

The accuracy and efficiency of progesterone (P4) and bovine pregnancy-specific protein B (bPSPB) radioimmunoassays (RIA) in detecting pregnant and nonpregnant dairy cows were compared at different stages of pregnancy. The study included 145 French Friesian heifers and cows from a single herd. A total of 175 artificial insemination (A.I.) and blood sampling procedures were performed. Animals were bled 24 d post AI for P4 RIA. They were bled at 24, 26, 30 to 35, and 70 +/- 9 after AI for bPSPB RIA. Females were declared nonpregnant when plasma P4 concentrations were lower than 1.5 ng/ml. With the bPSPB RIA, cows were nonpregnant when at least one of the B Bo x 100 replicates was higher than 95% in the RIA. When compared with palpations per rectum at 70 d, the accuracy of positive diagnoses (no. positive and pregnant/no. positive diagnoses) by P4 RIA at Day 24 was 67.2% (82 122 ). The accuracy of negative diagnoses was 98% (52 53 ). Accuracy of positive diagnoses by bPSPB RIA increased with gestation age (P<0.05) from 86.2% (50 58 ) on Day 24 to 98.8% (83 84 ) at time of palpation per rectum. Accuracy of negative diagnoses increased (P< 0.001) from Day 24 (71.8%; 84 117 ) to Days 30 to 35 (100%, 83 83 ). Efficiency in detecting nonpregnant females was much higher (P < 0.001) with the bPSPB RIA on Days 30 to 35 (90.2%; 83 92 ) than with the P4 RIA on Day 24 (56.5%, 52 92 ). It is concluded that 30 days after AI, the bPSPB RIA is an efficient test both for pregnancy prediction and detection of nonpregnant dairy cows.

Effects of dexamethasone on the responses of luteinizing hormone and testosterone to two injections of luteinizing hormone releasing hormone in young postpubertal bulls

Six young postpubertal bulls were studied in two experiments, 3 months apart. In experiment 1, three bulls received i.m. injections of dexamethasone (20 mg) and 5 h later these animals plus three control bulls received i.m. injections of luteinizing hormone releasing hormone (LH-RH, 250 microgram). In experiment 2, the controls from experiment 1 received dexamethasone and the treated animals from experiment 1 acted as controls for experiment 2. All bulls also received an i.m. injection of 250 microgram LH-RH on day 2 of each experiment. The concentrations of LH and testosterone in samples of jugular blood were determined by radioimmunoassay. There were no significant differences in the patterns of testosterone and LH release between the two experiments. On day 1, the response of LH to LH-RH was significantly (P less than 0.05) reduced by dexamethasone, but on day 2 values in the control and treated groups were similar although significantly (P less than 0.05) lower than values on day 1. The response of testosterone to LH-RH was not affected by dexamethasone. These results are discussed in terms of the site of action at which dexamethasone may act to depress the release of LH.

Peripheral plasma androstenedione and testosterone concentrations in bulls before and during puberty

Peripheral plasma samples were collected from 37 young bulls every other month from 2 to 12 months of age. Androstenedione and testosterone were measured by radioimmunoassays. Androstenedione values increased from 2 to 4 months of age (525 +/- 296 (s.d.) pg/ml) and then decreased. Testosterone concentrations increased regularly from 2 months (0.17 +/- 0.14 ng/ml) to 6 months (2.79 +/- 1.29 ng/ml) and then remained at levels around 3 ng/ml. Coefficients of correlation between the hormone concentrations were significant only at 6 months and thereafter.

Estrous behavior, progesterone in peripheral plasma and milk in dairy goats at onset of breeding season

Two large flocks of 60 and 120 French Alpine dairy does were studied beginning in late June. Estrous behavior was checked daily in the presence of bucks, and numerous blood and milk samples were collected. The end of the anestrus was characterized by consistent low progesterone around .1 ng/ml in plasma and 2 to 4 ng/ml in milk. Cyclic activity was detected in early July in one flock and in early August in the other. Individual patterns of plasma and milk progesterone in cyclic females were correlated greater than .5. Estrus was short (4 to 5 days) in 3 to 10 goats sampled daily following first estrus, and a small and transient rise of concentrations of progesterone was concomitant. Mean plasma and milk progesterone increased from about .1 to .5 and 2 to 4 ng/ml at the time of estrus to 6 to 8 in plasma and 6 to 10 ng/ml in milk 10 days later (midluteal phase). Twenty-one days after mating, concentrations in plasma and milk of pregnant animals were of the same magnitude as during the midluteal phase and higher than those in nonpregnant does (.1 to .7 and 2 to 3 ng/ml in plasma and milk).

Reproductive disorders in dairy cattle: I. Respective influence of herds, seasons, milk yield and parity

This study was performed in two large dairy units (with 130 and 213 calving cows each) during one year. The objectives were to investigate 1) epidemiological patterns of main post-partum reproductive disorders (metritis, post-partum and post-service anestrus, repeat breeding and embryonic death) and 2) the impact of herd, calving season, milk yield and parity on these patterns. Approximately 20% of the cows in both herds were not affected by any of the disorders. Prevalence of metritis was high (32 to 44%) and appeared influenced by the herds' conditions interacting with calving months and milk yield effects. Cyclic post-partum anestrus incidence was also essentially affected by the herd effect with an added seasonal interaction. Other disorders in both herds were also primarily subjected to the seasonal effect. Individual milk yield and parity only marginally affected the epidemiological patterns. We concluded that even in similar environmental conditions, no general patterns of incidence of reproductive disorders can be drawn and that they are essentially dependent on the characteristics of each herd management.

Exposure of in vitro-produced bovine embryos to foot-and-mouth disease virus

The aim of this study was to investigate whether foot and mouth disease virus (FMDV) interacts with in vitro produced (IVP) bovine embryos. One milliliter of a suspension of FMDV (2 x 10(7) TCID50/mL) was added to several batches of these embryos 7 d after in vitro fertilization, by which time they had either developed to the morula/blastocyst stage (n = 256) or degenerated (n = 260). Six experiments were performed in which developed or degenerated batches of embryos were incubated with FMDV for periods of 1 h (3), 2 h (2) or 4h (1). After this, the embryos were washed 10 times according to the International Embryo Transfer Society (IETS), then pooled and ground up to form a suspension, and assayed on cell cultures for FMDV. The cell cultures were observed daily for cytopathic effects for 3 d post exposure. In addition to the cell culture method, the polymerase chain reaction (PCR) technique was used to assay for the presence of the virus in the washing fluids. Assays for FMDV were also conducted on the first and second wash and on the pooled sample constituting the eight, ninth and tenth wash. With the exception of the second wash from a batch of embryos exposed to FMDV for 2 h, all samples of the first and second wash produced FMDV cytopathic effects, but none occurred with the pooled samples of the 8th, 9th and 10th wash. FMDV was also isolated from all but 1 of the batches of embryos after 1 h of incubation, from 1 of 4 batches after 2 h of incubation and from all batches after 4 h incubation. By contrast, the presence of virus could not be demonstrated by PCR based on the technique used here. These results show that 7 d old IVP bovine embryos can retain FMDV after washing, unlike in vivo-derived embryos, which do not appear to carry risks of FMDV transmission when washed according to IETS recommendations. Stricter controls are, therefore, necessary when using IVP embryos from cattle in a non-FMD-free zone in domestic or international trade.

Biosecurity and the various types of embryos transferred

The aim of the present paper was to review some features related to the risk analysis of three types of embryos to be transferred, namely the in vivo derived, the in vitro produced and the cloned ones. For in vivo-collected embryos, a considerable number of experiments and scientific investigations have been performed and hundreds of thousands of embryos are transferred annually with no contamination of associated diseases. Provided that the code of practice such as that published by the International Embryo Transfer Society is strictly followed by the embryo transfer practitioners, the statement made some 17 years ago saying that the in vivo-derived embryo transfer was the safest way of exchanging genes remains entirely true, thanks to the professionalism of the embryo transfer industry. For the in vitro-produced embryos, some particular rules have to be followed because of specific risks for some pathogens to strongly adhere to the zona pellucida of such embryos. There are some means to monitor and control those effects, and the transfer of in vitro-produced embryos can also be a very safe way to exchange genes around the world. The third type of embryos, the cloned ones, is a quite different category and the risk analysis to be soundly made still needs a lot of investigations so as to characterize the potential risks if there are, in terms not only of disease transmission but also in terms of public health, zoonotic risks as well as those related to quality and safety of food. The problem in this regard, is more directly addressed for offspring of clones than to the cloned embryos themselves. Published data on this issue are increasing in numbers so that progress in that area is expected in the few years to come.

Sources of variation of post-partum cyclicity, ovulation and pregnancy rates in primiparous Charolais cows treated with norgestomet implants and PMSG

In this study, sources of variation of postpartum cyclicity, ovulation and pregnancy rates were analyzed for 723 primiparous suckled Charolais cows treated with combined norgestomet implants (Crestar) and 600 IU PMSG (Chronogest) injected at the time of implant removal. The cows were inseminated 48 and 72 h after implant removal. Cyclicity and ovulation rate were estimated by progesterone assay and pregnancy rate by ultrasonography. At time of implant insertion, difficulty of previous calving, body condition score (BCS, from 1 to 5), interval from calving to implant insertion and herd related factors were recorded and their effects analyzed by logistic regression models. Cyclicity, ovulation and pregnancy rates were, respectively, 14.7% (106/723 ), 67.1% (381/568 ) and 42% (303/722 ) and were affected by BCS, calving conditions and interval from calving to implant insertion (P values from < 0.01 to < 0.0001). For ovulation and pregnancy rate, an interaction between BCS and interval from calving to implant insertion was found (P < 0.01). No other main factor or interaction was found to be significant. Cyclicity rate was lower in BCS1 (score < 2.5) cows (9.6%) than in BCS2 (19.8%) or BCS3 (score > 2.5) cows (22.4%), and decreased as difficulty of calving increased (23.2, 13.6 and 10.1%, respectively, for calving conditions 1, 2 and 3 cows). Cyclicity rate increased with interval from calving to implant insertion (8.2, 10.2 and 19.5%, respectively, for interval from calving to implant insertion < 60 d, between 60 and 70 d and > 70 d). Similar trends were found for ovulation rate. Previous difficult calving conditions influenced pregnancy rate negatively (47.9, 43.8 and 32.5% for calving conditions 1, 2 and 3 cows, respectively; P < 0,005).

Plasma concentration of luteinizing hormone, testosterone, dehydroepiandrosterone, androstenedione between birth and one year in the male dog: longitudinal study and hCG stimulation

A longitudinal study from peripheral blood, with samples collected every week, was performed between birth and one year of age on young Fox terriers dogs in order to determine the patterns of plasma LH, T, DHA and A concentrations. T, DHA, A curves show the same profile. The dog model shows the 3 successive steps preceding the adult life that are met in one year time: First, an infantile period between birth and the 12th week of age: the basal level of LH (4.29 ng/ml) and the 3 androgens levels (T less than 0.3 ng/ml, DHA less than 0.45 ng/ml, A less than 0.36 ng/ml) are low. A pubertal period, between the 13th week and the 36th week of age: we observe the maximum activity of the pituitary gland. The basal level of LH (7.97 ng/ml) significantly increase (P less than 0.001). The mean levels of androgens from 17 to 27 weeks of age are still quite low although significantly higher (P less than 0.03) for T and DHA than previously. After the 27th week of age, the androgens concentrations drastically increase. A post pubertal period begins at the 36th week of age. The mean LH (5.85 nh/ml) decrease. The androgens concentrations seem to plateau during the 12th month of age in the range of 2.5-5 ng/ml for T, 1.5-2.5 ng/ml for DHA and 1-2 ng/ml for A. hCG test (35 UI/kg, IM), with samples collected at 6, 12, 24, 30, 36 and 48 hours post injection, were performed at 1, 4, 7, 9 and 12 months of age. At 1 month, only minor variations were noticed; but after 4 months of age, for the 3 steroids, the same time course response was observed as in the adult dog: maximum levels were reached earlier for DHA (6-12 h) than for T and A (24 h).

Plasma LH and testosterone responses to synthetic gonadotrophin-releasing hormone (GnRH) or dexamethasone-GnRH combined treatment and their relationship to semen output in bulls

The sperm output of each of 54 dairy bulls of the Montbéliarde breed was carefully investigated from 15 weekly semen collections at 51-65 weeks of age. Assessment of classical characteristics of semen output led to classification of bulls as good, medium and poor semen producers. At 12 and 13 months of age, bulls were injected i.m. with 0.25 mg GnRH (N=25) or with 20 mg dexamethasone + 0.25 mg GnRH (N=29). Peripheral plasma LH and testosterone responses to these injections were evaluated from frequent sampling. In the two groups, the mean areas under the curve of LH (microgram/ml x 150 min) were significantly different between bulls (P less than 0.05). Intra-class correlation was 0.35 after the single GnRH administration (P less than 0.05) and 0.57 after dexamethasone-GnRH (P less than 0.05). This latter valve indicates a predominant individual influence over the LH response to such a combined treatment. No significant individual differences were seen from the testosterone responses to either of these challenges. Correlations between individual LH responses and any of the semen output criteria were not significant (P great than 0.05) and there were no significant differences in terms of mean LH responses between bulls in the 3 categories of semen production.