The effect of equine chorionic gonadotropin (eCG) on pregnancy rates of white-tailed deer following fixed-timed artificial insemination

Control of the white-tailed doe's reproductive cycle is not well documented. The objective was to determine the effects of giving equine chorionic gonadotropin (eCG) at progesterone device removal on fixed time artificial insemination (FTAI) pregnancy rates in white-tailed does. All does (n = 74) were synchronized with a vaginal progesterone implant (CIDR; 0.3 g progesterone), inserted on Day 0 (without regard to stage of estrous cycle), removed 14 days later, and subjected to FTAI, on average, 60 h post-CIDR removal. Of these, 34 were given 200 IU (im) of eCG at CIDR removal. Overall, FTAI pregnancy rate was 50% across 2 yrs (effect of year, P = 0.35). Administration of eCG at CIDR removal did not affect (P = 0.16) pregnancy rate (eCG = 59%; no eCG = 43%). Pregnancy rates were not affected by vulva score or doe disposition. Does that were ≤ 4 yrs old were more likely (P = 0.01) to become pregnant than does > 4 yrs of age. Does inseminated ≥ 60.5 h after CIDR removal were 22 times more likely (P = 0.002) to become pregnant to FTAI than does inseminated < 60.5 h. When frozen-thawed semen was deposited in the cervix or uterus, does were 17 times more likely (P = 0.005) to become pregnant compared with those receiving intravaginal insemination. Fecundity was not different (P = 0.73) across treatment groups (1.6 ± 0.11; no eCG vs. 1.7 ± 0.10; eCG). Furthermore, fecundity of does pregnant to FTAI was not different (P = 0.72) compared with does pregnant to clean-up bucks (1.7 ± 0.08; AI does vs. 1.7 ± 0.09; clean-up bucks). In summary, white-tailed does were successfully inseminated using a 14 days FTAI protocol, eCG may not be essential for acceptable pregnancy rates, and increased pregnancy rates may result when FTAI is done ≥ 60.5 h after progesterone device removal.     

Effect of sperm numbers and time of insemination relative to ovulation on sow fertility

We examined the effect of inseminating mixed parity sows (n = 231) once with fewer sperm at different times relative to ovulation. Lactation length was 19 days and sows received an IM injection of 600 IU equine chorionic gonadotrophin (eCG) 12 h before weaning. At 80 h after eCG injection, sows received an IM injection of 5 mg porcine luteinizing hormone (pLH). Predicted time of ovulation (PTO) was 38 h after pLH injection. Sows were assigned by parity to receive a single transcervical artificial insemination (AI) at either 6 or 24 h before PTO with semen doses containing either 2.5 or 1.25 × 10⁹ sperm. A positive control group of sows (n = 49) was subject to conventional AI 24 and 6 h before PTO. Detection of estrus was performed in the presence of a boar and only sows exhibiting estrous behavior at the assigned time of AI were included in the study. Farrowing rate for sows receiving 2.5 × 10⁹ sperm at 6 h before PTO was greater than that for sows receiving 1.25 × 10⁹ sperm at 24 h before PTO (85% versus 61%, P < 0.05). All other groups were intermediate. There was no effect of time of AI or sperm numbers on subsequent litter size. These data indicate that single insemination of fewer sperm may compromise sow fertility, even when performed transcervically, if not appropriately timed relative to ovulation.     

Deep intra-uterine artificial inseminations using cryopreserved spermatozoa in beluga (Delphinapterus leucas)

Artificial insemination (AI) with liquid-stored spermatozoa and sperm cryopreservation using directional freezing (DF) have been successful in the beluga. This study built on this foundation to develop a deep intra-uterine AI technique with frozen-thawed semen in beluga. Forty-two ejaculates from one male were cryopreserved using DF technology and subsequently used for 10 insemination attempts with seven females. Percentage pre- and post-thaw progressive motility and viability were (mean ± SD) 73.0 ± 12.2, 38.4 ± 8.8, 88.0 ± 0.1, and 59.3 ± 15.7%, respectively. A series of GnRH injections (3 x 250 μg, IV, 1.5 to 2 h apart) were used to induce ovulation, once a growing follicle >2.5 cm in diameter was visualized via trans-abdominal ultrasonography. Artificial insemination was performed at 30.1 ± 3.8 h post-initial GnRH injection with semen deposited in the uterine horn, 92.6 ± 16.2 cm beyond the genital opening using a flexible endoscope. The external cervical os (cEOS) was located beyond a series of 5 to 10 vaginal rings, 44.8 ± 9.3 cm from the external genital opening. The internal bifurcation of the uterus was 27 ± 6.8 cm beyond the cEOS. Ovulation occurred at 8.5 ± 7.6 h post-AI. Two of 10 inseminations (20%) resulted in pregnancy. The first pregnancy resulted in twins; both calves were born 442 d after AI, with one surviving. The second pregnancy is ongoing. These findings represent the first successful application of AI using frozen-thawed semen in beluga, and are important examples of how assisted reproductive technologies can provide tools for the global management of threatened species.     

Successful laparoscopic insemination with a very low number of flow cytometrically sorted boar sperm in field conditions

The aim of this study was to develop a useful procedure for laparoscopic insemination (LI) with sex-sorted boar spermatozoa that yields adequate fertility results in farm conditions. In experiment 1, we evaluated the effects of single (oviducts) and double (oviducts and tips of the uterine horns) LI with X-sorted sperm on the reproductive performance of sows. Sows (N = 109) were inseminated once as follows: (1) single LI with 0.5 × 10⁶ unsorted sperm per oviduct; (2) single LI with 0.5 × 10⁶ sex-sorted sperm per oviduct; or (3) double LI with 0.5 × 10⁶ sex-sorted sperm per oviduct and 0.5 × 10⁶ sex-sorted sperm per uterine horn. The farrowing rates were lower (P < 0.05) in sows inseminated with sex-sorted sperm (43.2% and 61.9% for the single and double insemination groups, respectively) than in sows from the unsorted group (91.3%). Within the sex-sorted groups, the farrowing rate tended (P = 0.09) to be greater in sows inseminated using double LI. There were no differences in the litter size among groups. In experiment 2, we evaluated the effect of the number of sex-sorted sperm on the reproductive performance of sows when using double LI. Sows (N = 109) were inseminated with sex-sorted sperm once using double LI with: (1) 0.5 × 10⁶ sperm per oviduct and 1 × 10⁶ sperm per uterine horn; or (2) 1 × 10⁶ sperm per oviduct and 2 × 10⁶ sperm per uterine horn. Similarly high pregnancy (90%) and farrowing (80%) rates were achieved in both groups. The sows inseminated with the highest number of sperm tended (P = 0.09) to have more piglets (10.8 ± 0.7 vs. 9.2 ± 0.6). A high female proportion (number of female births divided by the total of all births ≥0.92) was obtained in both experiments using X-sorted sperm. Our results indicate that the double LI procedure, using between 3 and 6 × 10⁶ sex-sorted sperm per sow produces adequate fertility at the farm level, making sperm-sexing technology potentially applicable in elite breeding units.     

Field fertility of frozen-thawed boar sperm at low doses using non-surgical, deep uterine insemination

The lowest dose of frozen-thawed boar sperm used for deep uterine artificial insemination (DUI) of sows has been 100x10(6). A three stage field study was performed to establish to what level the dose of frozen-thawed sperm used for DUI could be reduced without adversely affecting the fertility of the sow. In stage 1, 15 sows were inseminated twice with 1000x10(6) fresh or frozen-thawed sperm at 24 and 36 h post-detection of oestrus. In stage 2, 262 sows were inseminated with 62.5, 250 or 1000x10(6) fresh or frozen-thawed sperm at 24, 36, or 24 and 36 h after detection of oestrus. Stage 3 involved post mortem investigation of the uterine lining to assess damage caused by insertion of the insemination catheter. All sows inseminated in stage 1 of the study farrowed. In stage 2, the non-return (NRR) and farrowing rates of each group were compared to a control double cervical insemination of 3250x10(6) fresh sperm. As few as 62.5x10(6) fresh sperm could be deposited at a single insemination without reduction in NRR or farrowing rates compared with the control group. A double DUI with 250x10(6) frozen-thawed sperm was required before fertility was equivalent to the controls. Investigation of the uterine lining after insertion of the DUI catheter revealed evidence of bleeding, warranting further investigation of the viability of widespread use of the Firflex catheter, despite the promising fertility achieved here with low doses of spermatozoa.     

Fertility of weaned sows after deep intrauterine insemination with a reduced number of frozen-thawed spermatozoa

The present study evaluates the effectiveness of the transcervical deep intrauterine insemination (DUI) with a reduced number of frozen-thawed boar spermatozoa in weaned sows. DUI was performed using a specially designed flexible device (length 180 cm, outer diameter 4mm, working channel 1.8mm, working channel's volume 1.5 ml) that was inserted through an artificial insemination spirette to cross the cervix lumen and moved into one uterine horn as far as possible. Spermatozoa diluted in 7.5 ml of BTS were flushed into the uterine horn by a syringe attached to the working channel. In Experiment 1, 111 hormonally treated (eCG/hCG) weaned sows were inseminated once using one of the following three regimens: (1) DUI with frozen-thawed spermatozoa (1000 x 10(6) cells per dose; n=49); (2) DUI with fresh semen (150 x 10(6) cells per dose; n=29, as control of DUI procedure); and (3) cervical insemination with frozen-thawed spermatozoa (6000 x 10(6) cells diluted in 100ml; n=33). No differences (P>0.05) were found for farrowing rates (77.55, 82.76, and 75.76, respectively) or litter sizes (9.31+/-0.41, 9.96+/-0.32, and 9.60+/-0.53 piglets born per litter, respectively) among the groups. In Experiment 2, DUI was performed on the spontaneous estrus in weaned sows (2-6 parity) with 1000 x 10(6) frozen-thawed (40 sows) or 150 x 10(6) fresh spermatozoa (38 sows). The farrowing rate of sows inseminated twice with frozen-thawed spermatozoa (70%) was significantly (P<0.05) lower than with fresh semen (84.21%). No significant difference (P>0.05) was found in litter size between frozen-thawed spermatozoa (9.25+/-0.23 piglets born per litter) and fresh semen (9.88+/-0.21 piglets born per litter). These preliminary results indicate that application of DUI provides acceptable fertility in weaned sows using a relatively low number of frozen-thawed spermatozoa.     

Synchronization of ovulation and fertility in weaned sows treated with intravaginal triptorelin is influenced by timing of administration and follicle size

A 100 μg dose of triptorelin was tested for synchronizing ovulation in sows. In Experiment 1, conducted in April through June, sows (n = 125) were assigned to Control (untreated), TG-96 (Triptorelin Gel (TG) given intravaginally at 96 h post-weaning), or TG-E (given intravaginally at estrus). To optimize AI timing, sows were inseminated at 2 and 26 h after estrus for Control and TG-E and at 8 and 32 h following TG-96. Ovulation by 48 h post-treatment tended to be affected by treatment (P = 0.08) and more (P < 0.05) TG-96 sows ovulated (57.9%) compared to Controls (34.2%), but TG-E (45.1%) did not differ (P > 0.10). Duration of estrus was reduced (P < 0.005) in TG-96 (51 h) and TG-E (58 h) compared to Controls (65 h). There was no treatment effect on farrowing rate (71%) or total born (10.4). Average follicle size <6.5 mm at 96 h after weaning was associated with reduced (P < 0.01) estrus, ovulation and farrowing rate. Experiment 2 was conducted in August through September using 503 weaned sows. The TG-96 treatment reduced duration of estrus (P = 0.03), but treatment did not affect estrus expression, farrowing rate or total pigs born. In conclusion, use of a 100 μg dose of triptorelin intravaginally at 96 h or at estrus advanced ovulation and when used with timed insemination, resulted in similar farrowing rates and litter sizes comparable to sows mated based on estrus. However, ovulation induction and timed AI success may benefit from an approach that ensures sows have adequate follicle development at time of treatment.     

Caffeine, dibutyryl cyclic-AMP and heparin affect the chemotactic and phagocytotic activities of neutrophils for boar sperm in vitro

The objective was to examine the effects of caffeine, dibutyryl cyclic AMP, and heparin on the chemotaxis and/or phagocytosis of PMNs for porcine sperm. The chemotactic activity of PMNs, determined in a blind well chamber, increased (P < 0.05) when fresh serum was added to the medium (control containing BSA, 1109.5 cells/mm² vs serum, 1226.3 cells/mm²), regardless of the presence of sperm (control, 1121.1 cells/mm² vs serum, 1245.8 cells/mm²), whereas heat-inactivated serum did not affect activity (without sperm, 1099.4 cells/mm² and with sperm, 1132.6 cells/mm²). Regardless of live and dead sperm and of the origin of PMNs (boars vs sows), the phagocytotic activity of PMNs, as determined by co-culture of PMNs with sperm for 60 min, increased (P < 0.05) in the presence of fresh serum containing active complement (46.7 and 43.0%, respectively), but stimulation was decreased (P < 0.05) when 1 mM or higher concentrations of caffeine was added to the medium (from 40.7 to 20.8-31.6%). The origin of PMNs (sows vs boars) did not significantly affect phagocytotic activity. The percentage of PMNs that phagocytized polystyrene latex beads decreased when 2 mM caffeine was added to the medium containing porcine serum (from 43.7 to 21.5%). Serum-stimulated chemotactic activity of PMNs (1089.9 cells/mm²) was also reduced (P < 0.05) with 2 mM caffeine (942.5 cells/mm²). Furthermore, dibutyryl cAMP at ≥ 0.1 mM or heparin at ≥ 100 μg/mL decreased phagocytotic activity, in a concentration-dependent manner (P < 0.05). Supplementation of PMNs with heparin at 100 or 500 μg/mL decreased (P < 0.05) chemotactic activity in the presence of serum (from 1137.1 cells/mm² to 1008.8-1026.3 cells/mm²). We inferred that opsonization in the presence of active complement stimulated phagocytotic and chemotactic activities of PMNs, whereas supplementation with caffeine and dibutyryl cAMP (which could be associated with the intracellular cAMP level of PMNs) or adding heparin decreased serum-stimulated phagocytotic and chemotactic activities.     

A retrospective study on the preserving capacity of a commercial boar semen extender

The objective of this study was to evaluate the preserving capacity of a commercial, long-term boar semen extender beyond 4 days in terms of farrowing failure and total born per litter in sows and gilts. Data from 21 farms were subjected to logistic and linear regression analyses to assess the effect of parity (2-5, > 5 and gilts), wean-to-service interval (/= 6 days) and number of AI (1, 2, or 3) on the association between semen age (/=10 days) and fertility. As the semen age increased, the likelihood of farrowing failure increased and total born per litter decreased in sows and gilts. The effect of semen ageing on farrowing failure was more pronounced in sows than in gilts as in the latter it became significant only after 8 days. The effect of semen ageing on total born per litter was similar in both sows and gilts. A lower parity and wean-to-service interval were associated with a reduction in farrowing failure and increase in total born per litter in sows. Increasing the number of inseminations up to two was beneficial in reducing farrowing failure in sows and gilts. A third insemination increased the likelihood of farrowing failure in sows. The number of total born per litter in sows increased with number of inseminations and the effect was not significant in gilts.     

Effects of different artificial insemination techniques and sperm doses on fertility of normal mares and mares with abnormal reproductive history

The effects of different artificial insemination (AI) techniques and sperm doses on pregnancy rates of normal Hanoverian breed mares and mares with a history of barrenness or pregnancy failure using fresh or frozen-thawed sperm were investigated. The material included 187 normal mares (148 foaling and 39 young maiden mares) and 85 problem mares with abnormal reproductive history. Mares were randomly allotted into groups with respect to AI technique (routine AI into the uterine body, transrectally controlled deep intracornual AI ipsilateral to the preovulatory follicle, or hysteroscopic AI onto the uterotubal junction ipsilateral to the preovulatory follicle), storage method of semen (fresh, frozen-thawed), AI volume (0.5, 2, 12 ml), and sperm dose (50 x 10(6) or 300 x 10(6) progressively motile sperm (pms) for fresh semen and 100 or 800 x 10(6) frozen-thawed sperm with >35% post-thaw motility). The mares were inseminated once per cycle, 24 h after hCG administration when fresh semen was used, or 30 h for frozen-thawed semen. Differences in pregnancy rates between treatment groups were analyzed by Chi-squared test, and for most relevant factors (insemination technique, mare, semen, and stallion) expectation values and confidence intervals were calculated using multivariate logistic models. Neither insemination technique, volume, sperm dose, nor mare or stallion had significant effects (P > 0.05) on fertility. Type of semen, breeding mares during foal heat, and an interaction between insemination technique, semen parameters, and mares did have significant effects (P < 0.05). In problem mares, frozen semen AI yielded significantly lower pregnancy rates than fresh semen AI (16/43, 37.2% versus 25/42, 59.5%), but this was not the case in normal mares. In normal mares, hysteroscopic AI with fresh semen gave significantly (P < 0.05) better pregnancy rates than uterine body AI (27/38, 71% versus 18/38, 47.3%), whereas in problem mares this resulted in significantly lower pregnancy rates than uterine body AI (5/15, 33.3% versus 16/19, 84.2%). Our results demonstrate that for problem mares, conventional insemination into the uterine body appears to be superior to hysteroscopic insemination and in normal mares, the highest pregnancy rates can be expected by hysteroscopic insemination.     

New aspects of boar semen freezing strategies

Although cryopreserved boar semen has been available since 1975, a major breakthrough in commercial application has not yet occurred. There is ongoing research to improve sperm survival after thawing, to limit the damage occurring to spermatozoa during freezing, and to further minimize the number of spermatozoa needed to establish a pregnancy. Boar spermatozoa are exposed to lipid peroxidation during freezing and thawing, which causes damage to the sperm membranes and impairs energy metabolism. The addition of antioxidants or chelating agents (e.g. catalase, vitamin E, glutathione, butylated hydroxytoluene or superoxide dismutase) to the still standard egg-yolk based cooling and freezing media for boar semen, effectively prevented this damage. In general, final glycerol concentrations of 2-3% in the freezing media, cooling rates of -30 to -50 degrees C/min, and thawing rates of 1200-1800 degrees C/min resulted in the best sperm survival. However, cooling and thawing rates individually optimized for sub-standard freezing boars have substantially improved their sperm quality after cryopreservation. With deep intrauterine insemination, the sperm dose has been decreased from 6 to 1x10(9) spermatozoa without compromising farrowing rate or litter size. Minimizing insemination-to-ovulation intervals, based either on estimated or determined ovulation, have also improved the fertility after AI with cryopreserved boar semen. With this combination of different approaches, acceptable fertility with cryopreserved boar semen can be achieved, facilitating the use of cryopreserved boar semen in routine AI programs.     

Artificial insemination with cryopreserved sperm from feline epididymides stored at 4 °C

Recovering and storing sperm from the epididymides of males of rare felidae is useful for preserving the species. The objective of the present study was to determine pregnancy rates following artificial insemination (AI) of frozen-thawed epididymal sperm, which were cryopreserved following low-temperature storage of the epididymides. In this study, these sperm were used for unilateral intrauterine AI (UIUAI) or unilateral intratubal AI (UITAI) using 40 × 10⁶ and 10 × 10⁶ sperm, respectively. The caudal epididymides of 17 cats were stored at 4 °C for 24 h after castration. Artificial insemination of seven female cats was performed on Days 3 or 4 (start of estrus = Day 1) by UIUAI, 20 h after injection of 100 IU hCG to induce ovulation. Furthermore, UITAI at 24 h (UITAI-24) or 30 h (UITAI-30) after hCG were also done (five cats per group). It was noteworthy that AI by UIUAI and UITAI-24 was performed before ovulation, whereas AI by UITAI-30 was performed after ovulation. Pregnancy rates were 28.6% (2/7) by UIUAI, 80% (4/5) by UITAI-24, and 20% (1/5) by UITAI-30. Litter size was one or two by UIUAI, and one to four by UITAI. Spontaneous abortion occurred on Days 25-30 of pregnancy in one of the two female cats pregnant following UIUAI, and in two of five female cats pregnant following UITAI. Based on the high pregnancy rate obtained with 10 × 10⁶ sperm in the UITAI-24 group (AI performed before ovulation), we concluded that this was the most appropriate method for AI with frozen-thawed epididymal sperm after initial low-temperature storage of epididymides.     

Treatment of swine summer infertility syndrome by means of oxytocin under field conditions

Endogenous oxytocin is released by the sow at the time of mating in response to stimulation by the boar, which may explain, at least partially, the importance of the relationship between the boar's courting activity and the subsequent reproductive performance of the sow. The aim of this study was to determine the effects on reproductive performance of supplementing AI doses with exogenous oxytocin during the low fertility season. At an intensive piggery in northwest Spain 3 experimental groups were randomly formed and observed throughout the year. Group 1 sows were inseminated with semen supplemented with 4 IU oxytocin. Group 2 sows received 4 IU oxytocin injected through the vulvar lips mucosa at the time of insemination. Group 3 sows were inseminated without oxytocin and served as the controls. During the low fertility season the results for each group were as follows: farrowing rate 77.02, 56.25 and 54.39%, and litter size 10.77 +/- 0.28, 10.45 +/- 0.31 and 8.53 +/- 0.34 respectively. It is concluded that the addition of oxytocin to seminal doses just before AI is an easily applicable, effective method for increasing fertility and litter size during the summer months.     

Effect of insemination of estrus-induced prepuberal gilts on ensuing reproductive performance and body weight

Prepuberal gilts reared and managed to 85-90 kg live weight in a common system were allocated at random to one of three first-mating treatments in an experiment conducted over a period of more than 5 years. In two of the treatments, gilts received a single i.m. injection of 400 IU equine chorionic gonadotropin (eCG) and 200 IU human chorionic gonadotropin (hCG) (PG600; Intervet) and were either inseminated 4 and 5 days later on a fixed-time basis regardless of oestrus (treatment A), or at the second oestrus following treatment (treatment B). The third group of gilts remained untreated and was inseminated on the first spontaneous oestrus (treatment C). Thereafter, all gilts were managed in the same way and those observed in oestrus were re-inseminated. Significantly more gilts returned to oestrus after the first service in treatment A (35%) than in treatment B and C (12 and 17%, respectively; P<0.01). Gilts farrowed to the first or repeat inseminations at a significantly younger age (P<0.01) in treatment A (304 days) than treatment B (324 days) and C (320 days). The age difference at farrowing remained in surviving gilts at the end of their third parity. The first farrowing performance of the gilts was significantly affected by treatment in terms of litter size at birth (A 7.0, B 8.4 and C 8.3 live piglets per gilt; P<0.01), litter size at weaning (A 6.2, B 7.2 and C 7.2 live piglets per gilt, P<0.05), and piglet birth weight (A 1.4, B 1.3 and C 1.3 kg; P<0.05) but piglet survival rate and weaning weight were not affected by treatment. The live weights of the gilts were significantly different between the treatments at first insemination (A 95.7, B 106.5 and C 109.2 kg; P<0.01) but not when the first litter was weaned (A 133.6, B 135.1 and C 136.6; P>0.05). After the first farrowing there were no differences between the treatments in terms of the survival rate, productive or reproductive performance of the gilts/sows and their offspring. Without conducting a detailed cost-benefit-calculation it was deduced that, from an economical point of view, differences between treatment A and treatments B and C are negligible because the savings associated with farrowing at a younger age on this treatment just about compensated for any additional costs associated with the treatment and the lower number of piglets born at the first farrowing.     

Field fertility with exported boar semen frozen in the new flatpack container

The present study tested the field fertility of frozen-thawed (FT) Swedish boar semen packaged in flat plastic containers (FlatPacks) and exported for artificial insemination (AI) to overseas nucleus herds. Semen from 47 Swedish boars of Landrace (L), Yorkshire (Y), and Hampshire (H) breeds was frozen using a lactose-egg yolk-based extender with 3% glycerol and 10(9) spermatozoa/ml in 5 ml FlatPacks. For all breeds, FT sperm membrane intactness averaged 60%, while mean FT sperm motility ranged from 49 to 53%. A total of 308 litters resulted from 421 overseas inseminations with FT semen, with a mean farrowing rate (FR) of 73% and 10.7 mean number total piglets born. In a within-sow analysis for the purebred L and Y breedings, the FR and litter size of FT semen were compared with natural matings (NM) and on-farm AI with liquid semen (NW/AI breedings) at the same farms. Farrowing rate was 72.3 and 78.8% (P = 0.23), total piglets 11.3 and 11.6 (P = 0.44), and live piglets 10.1 and 10.2 (P = 0.77), for the FT semen and NM/AI breedings, respectively. The present results suggest that this freezing protocol and FlatPack container maintains high sperm viability post-thaw. Further the fertility levels when inseminated at overseas nucleus herds seem to be similar to those achieved with (NM/AI breedings) at the same farms. This freezing method may be a reliable alternative for the freezing/thawing of boar semen under commercial AI conditions.     

Early pregnancy loss in sows after low dose, deep uterine artificial insemination with sex-sorted, frozen-thawed sperm

Recent developments in reproductive technologies have enabled the production of piglets of a predetermined sex via non-surgical, low dose artificial insemination. The practical application of sex-sorting technology to the pig is made challenging by the large numbers of sperm required for successful insemination of sows. One way of overcoming the time required for sex-sorting may be to create a bank of cryopreserved, sex-sorted sperm, thus making available appropriate doses as sows require insemination. To date, little success has been achieved with non-surgical inseminations of sex-sorted boar sperm. This study attempted to achieve litters of a predetermined sex after a double insemination of sows with 160x10(6) sex-sorted, frozen-thawed sperm. Sows were synchronised and sperm were non-surgically inseminated into the proximal third of the uterine horn at 36 and 42 h after hCG administration. Sows inseminated with sex-sorted sperm achieved similar pregnancy rates to those receiving an equal dose of unsorted, frozen-thawed sperm. However, all sows conceiving after insemination with sex-sorted sperm returned to oestrus within 57 days of insemination. This was a higher rate of pregnancy loss than observed for sows inseminated with unsorted sperm (37.5%; P=0.031). A combination of low sperm numbers and potentially compromised developmental capability of embryos derived from sex-sorted sperm may have resulted in this early stage loss of pregnancy.     

Effect of PG600 and adjusted mating times on reproductive performance in weaned sows

The administration of PG600 to sows at weaning induces >90% of sows to return to estrus within a week, but farrowing rate and litter size are often not improved. This study evaluated the effects of adjusted artificial insemination (AI) times based on weaning to estrus interval (WEI) and estrus to ovulation interval (EOI) following PG600. All sows were given PG600 at weaning and allotted to adjusted (ADJ, n=47) or non-adjusted (NA, n=46) mating times after the onset of estrus. Adjusted mating involved: (1) 2-3 days WEI, AI at 36 h and 48 h; (2) 4 days WEI, AI at 24h and 36 h; (3) 5 days WEI, AI at 12h and 24h; and (4) 6-7 days WEI, AI at 0 h and 12h. Mating for NA occurred at 0 h and 24h after onset of estrus. There was no effect of treatment on return to estrus (92.9% versus 92.5%) or ovulation (92.7% versus 92.5% for ADJ and NA, respectively). The proportion of first AI occurring within 24h prior to ovulation was increased (83.8% versus 50.0%) and closer to ovulation for ADJ compared to NA treatment (19.4h versus 27.3h, P<0.05). Treatment did not influence (P>0.10) the proportion of second AI occurring within 24h of ovulation (72.8% versus 56.6%) but did influence (P<0.05) the interval from second AI to ovulation for ADJ compared to NA (10.6h versus 3.3h). The ADJ treatment increased (P<0.05) the proportion of sows that received an AI within 24h before ovulation (98.8% versus 87.0%). However, treatment did not influence pregnancy (87.4%) or farrowing (79.5%) rates but the NA treatment tended to increase (P<0.10) total number of pigs born (11.8 versus 8.9). In conclusion, while AI times for ADJ appeared to occur within optimal periods, farrowing rates were not improved and litter size decreased, suggesting that two AI at 12h intervals and closer to the time of ovulation may be detrimental. Overall, these data suggest that for sows injected with PG600 at weaning and receiving two AI, breeding at 0 h and 24h after onset of estrus is recommended.     

Dissimilarities in sows' ovarian status at the insemination time could explain differences in fertility between farms when frozen-thawed semen is used

Deep intrauterine insemination (DUI) offers a suitable alternative for the commercial use of frozen-thawed boar semen. The present study evaluated how the ovarian status at DUIs of frozen-thawed spermatozoa (1 x 10(9) spz/dose, two DUIs, 30-31 and 36-37 h after detection of oestrus) in 179 sows would explain differences in fertility between two farms with similar, but not equal, reproductive management (experiment 1). A further experiment investigated whether an increase in sperm number per AI-dose (1 versus 2 x 10(9) spz/dose, two DUIs, 30-31 and 36-37 h after detection of oestrus, on 228 sows) could minimize this effect (experiment 2). Ovaries were checked by transrectal ultrasonography at the time of DUI and sows were classified into three categories: F-: ovarian pre-ovulatory follicles were visible during two examinations; O-: ovulation visible during one examination; and C-sows: corpora hemorragica visible during the two examinations. Overall farrowing rates differed (P < 0.01) between farms (70.1 versus 51.2%, farms A and B, respectively). Distribution of sows among ultrasonography categories also differed (P < 0.05) between farms (17.5, 72.2 and 10.3% were classified as F-, O- and C-sows in farm A, versus 40.2, 29.3 and 30.5% in farm B). Nevertheless, farrowing rates and litter sizes within categories did not vary between farms (P > 0.05). In addition, a two-fold increase in the number of spermatozoa per DUI improved (P < 0.05) fertility in F- and C-sows, but not in O-sows. In conclusion, the interval DUI-to-ovulation provides a major explanation for fertility differences between farms when frozen-thawed spermatozoa are used.     

Effect of oxytocin and flunixin meglumine on uterine response to insemination in mares

The most probable reason for persistent postbreeding endometritis in mares is weak myometrial contractility. The influence of oxytocin (OT; an ecbolic agent) and flunixin meglumine (FLU; a prostaglandin inhibitor serving as a model for mares with decreased uterine contractility) on uterine response to artificial insemination (AI) was studied in mares with no history of reproductive failure. The mares were treated intravenously with 10 mL saline (Group C, n = 10) or 0.01 IU/kg OT (Group OT, n = 10) 2, 4, 8, and 25 h after AI. Group FLU (n = 11) was treated with 1.1 mg/kg FLU 2 h after AI and with saline thereafter. The mares received the same treatments in the first and third cycles but were sampled either at 8 or 25 h. The amount of intrauterine fluid (IUF) and edema and the number of uterine contractions were recorded before AI and 10 min after the treatments using transrectal ultrasonography. At 8 h after AI, the mares were treated with human chorionic gonadotropin, and, after 8-h or 25-h scans, a 500-mL uterine lavage and a biopsy were performed. Ovulation was confirmed at 48 h and pregnancy 14 to 17 d after AI. No manipulations were done during the second estrus. At 8 h after AI, Group FLU had more polymorphonuclear leukocytes (PMNs) in the uterine lavage fluid than did Group OT (P < 0.05), but uterine contractions did not differ significantly. At 25 h, the PMN concentrations were low in all groups. Group OT rarely showed IUF. The uterine biopsy specimens of Group FLU showed less inflammation of the stroma but more PMNs in the uterine lumen 8 h after AI than that of the control group (P < 0.05). The pregnancy rates did not differ between the groups (63% C, 53% OT, and 50% FLU). Oxytocin rapidly and effectively removed IUF and PMNs after AI and thereby shortened the duration of postbreeding inflammation.     

Fertility of frozen-thawed porcine semen following controlled-rate freezing in straws

A method was developed for freezing large batches of porcine semen in straws at a controlled rate in a liquid nitrogen programmable freezer. The fertilizing potential of spermatozoa frozen by this method was examined by inseminating 220 sows with a mixture of semen from two boars. Estrus was synchronized using one of two regimens and sows were inseminated once at 34 h after human chorionic gonadotropin (hCG) treatment. The average pregnancy rate at 60 d of gestation, farrowing rate and litter size were 60.9%, 51.4% and 8.8, respectively. The fertilizing potential of spermatozoa frozen by this method appeared to be similar to that reported for other methods of freezing porcine semen.