Effects of prostaglandin F2 alpha and pregnant mares' serum gonadotropin (PMSG) on the reproductive performance of fluorogestone acetate PMSG-treated ewes

Two experiments were conducted to examine the effect of prostaglandin F2 alpha (PGF2 alpha) and pregnant mares' serum gonadotropin (PMSG) on the reproductive performance (fertility, prolificacy and fecundity) of ewes previously treated with fluorogestone acetate (FGA) and PMSG. In the first experiment, 29 ewes were synchronized for estrus with FGA and PMSG but not bred at the postsynchronization estrus. On day 10 of the first post-synchronization estrous cycle, they were injected IM with 15 mg PGF2 alpha and 500 IU PMSG and exposed to experienced, fertile, raddled rams. Twenty-four of the 29 ewes (83%) had viable fetuses 9 weeks after the PGF2 alpha-PMSG treatment. In the second experiment, 64 ewes were treated with FGA-PMSG, and 33 were exposed to fertile, raddled rams at the synchronized estrus. A second group of 31 ewes was not bred at the synchronized estrus, but on day 12 of the postsynchronized estrous cycle, they were injected IM with 15 mg PGF2 alpha and 500 IU PMSG and exposed to fertile, raddled rams. Sixty-six percent of the 33 ewes lambed in the FGA-PMSG-treated group and 60% of the 31 ewes lambed in the PGF2 alpha-PMSG-treated group. Differences in reproductive performance between these two treatment groups were not statistically significant. The results suggest that the PGF2 alpha-PMSG treatment combination does not adversely affect reproductive performance of ewes.     

Fertility of ewes inseminated intrauterinally with frozen semen using extender containing bovine serum albumin

The present study was conducted to examine the fertility of ewes inseminated intrauterinally with frozen semen using semen extender containing either egg yolk or bovine serum albumin (BSA). Sixty Suffolk and cross-bred ewes were treated with controlled internal drug release (CIDR) devices during the non-breeding season (July 2006). A CIDR was inserted into the vagina for 12 days and an intramuscular injection of 500 IU equine chorionic gonadotropin was administered one day before its removal. Ejaculates from a suffolk ram were diluted with a Tris-based extender containing either 15% (v/v) egg yolk or 10% (w/v) BSA, and the diluted semen was frozen in 0.25 ml straws. A fixed-time intrauterine artificial insemination (AI) was performed 43-47 h after CIDR removal, regardless of incidence of estrus. There was no significant difference in pregnancy rates at 60 days after AI between the extenders containing egg yolk (66.7%, 20/30 animals) or BSA (65.5%, 19/29 animals). Furthermore, there were no significant difference in the lambing rates (66.7% and 62.1%) and prolificacy (1.25 and 1.56) between the two semen extenders. The present study indicates that a semi-defined semen extender containing 10% BSA produces fertility after intrauterine AI that is similar to that achieved with semen extender containing egg yolk.     

Influence of PMSG and time of artificial insemination on fertility of progestogen-treated sheep in confinement

The need for pregnant mates' serum gonadotropin (PMSG) in breeding confined sheep by artificial insemination (AI) at progestogen-synchronized estrus was assessed in 152 adult crossbred ewes brought into season by a controlled light regimen. One-half of the ewes received 500 IU PMSG after intravaginal progestogen treatment; all ewes were inseminated either 54, 57 or 60 h after sponge removal or at 54 and again at 60 h. Based on progesterone determinations 18 d after AI, conception rates with single insemination 54, 57, or 60 h and double insemination at 54 and 60 h were 76, 72, 47 and 72%, respectively, among ewes receiving PMSG, compared to 17, 22, 47 and 43%, respectively, among ewes not give PMSG (P less than .01) Lambing rates were higher (P less than .01) with PMSG (67, 67, 37 and 61%) than without PMSG (11, 11, 26 and 33%). While there was only a small increase (.06 less than P less than .05) in litter size with PMSG, fecundity decreased (P less than .01) from 1.4 to .3 when PMSG was not used. These data indicate that, even with controlled lighting to induce estrous activity, additional stimulation of ovulation by PMSG at progestogen-synchronized estrus is necessary for normal fertility when confined sheep are bred by AI.     

Fertility after artificial insemination using a soybean-based semen extender in sheep

The present study aimed to compare the fertility of ewes intrauterinally inseminated with frozen-thawed semen using a soybean-based semen extender (AndroMed) with those of ewes intrauterinally inseminated with frozen-thawed semen using a Tris-based extender containing either egg yolk or BSA. Suffolk ewes (n=104) were treated with an intravaginal sponge containing 40 mg fluoroprogesterone acetate (FGA) for 12 days and an intramuscular injection of 500 IU equine chorionic gonadotropin to induce estrus and ovulation during the non-breeding season (July, 2007). Intrauterine insemination was carried out 40-46 h after removal of the FGA sponge (n=90), regardless of the incidence of estrus. The pregnancy rates were not significantly different among the semen extenders containing egg yolk (64.5%) or BSA (58.6%) and AndroMed extender (56.7%). The lambing rates (64.5, 55.2 and 56.7% for the semen extenders containing egg yolk, BSA and AndroMed, respectively) and prolificacy (1.59 to 1.75) were also not significantly different. The present results indicate that an egg yolk-containing semen extender can be replaced with the non-animal derived extender AndroMed, which could be used for intrauterine insemination using frozen-thawed ram semen without reducing fertility.     

Influence of body weight and number of inseminations on fertility of progestogen-treated ewe lambs raised in controlled environments

The influence of body weight at breeding on reproductive response to one and two artificial inseminations (AI) of fresh extended semen was assessed in 195 crossbred ewe lambs selected for early breeding and compared with 159 adult ewes, all housed indoors in a controlled environment. In six trials, ewe lambs and adult ewes in progestogen-induced estrus were inseminated 55 to 57 h after sponge removal. One-half of the lambs and one-fourth of the adults received a second insemination at 60 h. Resultant reproductive performance of both groups indicated no advantage in a double insemination. Overall fertility, litter size and fecundity after one and two inseminations were 33%, 1.7 and .6 for ewe lambs and 68%, 2.4 and 1.6 for adult ewes, respectively. Embryonic mortality after the first 2 wk of pregnancy was estimated at 24% for ewe lambs and 9% for adults. The influence of body weight was analyzed by grouping the ewe lambs according to body weight at breeding. The lambs in group 1 weighed 30 to 35 kg; group 2, 36 to 40 kg; group 3, 41 to 45 kg and group 4, 46 to 50 kg. The proportion of ewes lambing in groups 1, 2, 3 and 4 was 16, 34, 39 and 48%, respectively. Corresponding litter sizes were 1.4, 1.6, 1.8 and 2.0. Fecundity increased (P less than 01) from .2 in group 1 to 1.0 in group 4. The results indicate that even when ewe lambs are bred by AI (eliminating a ram behavioral problem), sheep with heavier body weights produce more lambs per ewe bred.     

冷冻精液输精深度和时间对蒙古羊受胎率的影响

[目的] 研究冷冻精液输精深度和时间对蒙古羊受胎率的影响。[方法] 选取体况健康、繁殖机能正常的蒙古羊母羊作为试验动物,采用孕酮海绵栓对受体母羊进行同期发情处理。应用常规人工输精法（n=135）、过子宫颈输精法[过子宫颈第一皱褶（1~2 cm）输精（n=120）,过子宫颈第二到第三皱褶（3~4 cm）输精（n=120）]、腹腔镜辅助子宫内输精法（n=128）对发情后的母羊进行冷冻精液人工授精。接受常规人工输精法和过子宫颈输精法处理的受体母羊在发情后约14 h和22 h各输精1次,接受腹腔镜辅助子宫内输精法处理的受体母羊在发情后30~36 h输精1次。输精后40 d用B超仪检测母羊妊娠情况,计算并比较接受不同输精方法处理母羊的受胎率。[结果] 腹腔镜辅助子宫内输精法的受体母羊受胎率平均值最高,为60.2%;其次为过子宫颈第二到第三皱褶（3~4 cm）输精,受胎率平均值为58.3%;过子宫颈第一皱褶（1~2 cm）输精和常规输精法的受体母羊受胎率平均值分别为37.5%和36.3%。统计学分析表明,腹腔镜辅助子宫内输精法和过子宫颈第二到第三皱褶（3~4 cm）输精的受体母羊受胎率平均值显著（P<0.05）高于常规输精法和过子宫颈第一皱褶（1~2 cm）输精。[结论] 蒙古羊母羊发情后30~36 h采用腹腔镜辅助子宫内输精法完全穿刺子宫颈输精1次,可获得比常规输精法更高的受胎率;采用过子宫颈输精法在母羊发情后约14 h和22 h各输精1次,当授精深度接近4 cm时可达到与腹腔镜辅助子宫内输精法接近的受胎率。     

羊同期发情腹腔镜输精最佳时间的研究

[目的]确定羊同期发情腹腔镜输精的最佳时间。[方法]选取繁殖机能正常、营养状况良好的适龄母羊,在试验母羊阴道内放置孕酮海绵栓10~14 d,撤栓时肌肉注射250~330 IU/只孕马血清促性腺激素（PMSG）。撤栓后12~24 h开始试情,早晚各1次。按撤栓后时间及发情时间不同分4组进行腹腔镜输精：1组为撤栓后46~50 h输精（n=138）,2组为撤栓后50~54 h输精（n=156）,3组为撤栓后54~58 h输精（n=275）,4组为羊发情后30~36 h输精（n=226）。输精后第40~45天进行B超检查,计算各组母羊受胎率。[结果]发情后30~36 h输精的母羊（4组）受胎率最高,为97.79%,其次为撤栓后50~54 h输精的母羊（2组）,受胎率为97.44%,撤栓后46~50 h输精的母羊（1组）受胎率为91.30%;撤栓后54~58 h输精的母羊（3组）受胎率最低,为89.82%。[结论]采用同期发情配合腹腔镜输精技术进行母羊人工授精,最佳输精时间为撤栓后50~54 h以及母羊发情后30~36 h。     

Some factors affecting pregnancy rate in ewes following laparoscopic artificial insemination

The fertility of 646 ewes and gimmers bred by laparoscopic artificial insemination (LAI) in the autumn of 2006 was investigated using a questionnaire and individual ewe breeding records kept for 13 commercial sheep flocks that used LAI routinely. Overall, the pregnancy rate was 66 per cent, but it was highest in ewes bred for the fourth time. Technical aspects of LAI influenced fertility: pregnancy rates were 70 per cent for ewes bred using frozen semen compared with 58 per cent when fresh semen was used (P≤0.01), and 74 per cent of ewes that travelled to an artificial insemination centre for mating conceived, compared with 62 per cent that remained on their own farm (P<0.01). Higher doses of equine chorionic gonadotrophin (>400 iu) used for oestrus synchronisation reduced pregnancy rates to only 49 per cent (P<0.001). However, the largest effect was associated with shepherds gathering, handling and treating breeding ewes four to six weeks before mating; pregnancy rates were 54 per cent among ewes where this was carried out, compared with 74 per cent for ewes not treated in this way (P<0.01).     

Improvement of Fertility in Artificially Inseminated Ewes Following Vaginal Treatment with Misoprostol Plus Terbutaline Sulphate

The effect of vaginal administration of misoprostol plus terbutaline sulphate 6 h prior to artificial insemination (AI) upon the site of AI (vaginal or cervical) and fertility was studied using a total of 87 estrous synchronized Serra da Estrela ewes (control n = 42 and treated n = 45). Artificial insemination was performed using refrigerated semen at 54–55 h after sponge removal. Lambing rate (fertility) and prolificacy were compared between control and treated ewes. The effect of the site of semen deposition on fertility was also evaluated. Prolificacy rate was not different between control (1.5) and treated (1.59) ewes. The proportion of cervical AI achieved in control (45.2%) and treated (37.8%) ewes was not significantly different. Overall, fertility was significantly lower in control than in treated ewes (42.9% vs 64.4%; p < 0.04). Fertility following vaginal AI was significantly lower for control for than treated ewes (30.4% vs 60.7%; p < 0.03) but the difference was smaller and not significant for cervical AI (control 57.9% vs 70.6%). It was concluded that vaginal administration of misoprostol plus terbutaline sulphate 6 h prior to artificial insemination did not affect the proportion of cervical inseminations but significantly improved the fertility of treated ewes. Although needing confirmation, it was hypothesized that drugs might have induced local secretory modifications leading to an increase of cervical ability to retain more viable spermatozoa for fertilization.     

Effect of megestrol acetate and progesterone on oestrous and fertility in cyclic Malpura and Chokla ewes

In Rajasthan, India megastrol acetate and progesterone were administered to ewes (25 Chokla, 25 Malpura, aged between 3 and 4) in November 1968. Each ewe received 50 mg of either megastrol acetate or progesterone. Administration was intravaginal or intramuscular. During treatment only 3 ewes (2 megastrol acetate-injected and 1 progesterone-injected ewes) came into heat; thus, the progestogens exerted an inhibiting effect. 76% and 88% of the megastrol acetate and progesterone ewes, respectively, exhibited heat within 96 hours of therapy's end. Breed showed no significant effect on occurrence of estrus after therapy. Release of estrus within 96 hours occurred in 91.3% and 74.0% of intravaginally and intramuscularly treated ewes, respectively. 17 (41.5%) of the 41 ewes inseminated at their synchronized estrus lambed as a result of breeding in that first cycle. Thus, questions arise as to efficiency of ovulation, fertilization, nidation, and lambing in the case of synchronized estrus by use of different progestogens. 75% of ewes showing typical fern pattern at insemination lambed. An antiseptic vaginal douche applied after withdrawal of the sponge used in iv administration might be responsible for increased posttreatment fertility in this group.     

Oxytocin increases pregnancy rates after fixed time artificial insemination in Kazak ewes

It is probable that reduced pregnancy rates in ewes after fixed time artificial insemination (FTAI) is attributable, in part, to the reduced number of normal spermatozoa that colonize the oviduct. Administration of oxytocin stimulates both cervical dilation and uterine/oviductal contractility. The hypothesis that oxytocin can enhance sperm transport into the uteri and the oviducts, and thereby increase pregnancy rates, was tested in the present study. Oestrus was synchronized in 199 multiparous Kazak ewes using intravaginal flurogestone-impregnated sponge. The sponge was left in the vagina for 12 days followed with an injection of 330 IU of eCG at sponge removal. Each ewe was intracervically inseminated twice at 50 hr and 62 hr after the removal of sponges using an insemination catheter containing 0.25 ml of diluted semen. Semen was collected from seven Texel rams and all the ejaculates were pooled and diluted in ultra-high temperature-treated commercial skimmed milk without (Control group, 0.05 ml of saline per mL milk, n = 144) or with oxytocin supplement (Oxytocin group, 0.5 U of oxytocin per ml milk, n = 55). Pregnancy status was determined by transabdominal ultrasound examination 45 days after insemination. Lambing performance was recorded at delivery. Significant differences were observed between the Oxytocin group and the Control group in terms of the pregnancy rate and the fecundity rate (85.5% and 92.7% versus 68.8% and 72.9%, respectively). In conclusion, low dose oxytocin supplementation of semen extender significantly increased pregnancy and fecundity rates in oestrus-synchronized Kazak ewes after FTAI.     

Synchronization of estrus and reproductive performance of ewes treated with synthetic progestogens administered by subcutaneous ear implant or by intravaginal sponge pessary

Experiments were conducted to compare the efficacy of synthetic progestogens administered by subcutaneous ear implant or intravaginal sponge to induce a synchronized estrus in adult ewes and ewe lambs and to evaluate reproductive performance (fertility and litter size) to breeding at the synchronized estrus. Experimental animals were representative of three strains maintained in total confinement and exposed to a synthetic light regimen which alternated at intervals of 4 mo from 18 h day length to 10 h day length/24 h. Treatments were applied at different times of the year at the end of a low light cycle. Implants contained Norgestomet (3 mg) impregnated in a polymethacrylate polymer (Implant H) or impregnated in a silastic polymer containing 1.05 (Implant S1), 1.78 (Implant S2) or 2.60 mg (Implant S3) Norgestomet, respectively. Intravaginal sponges contained 40 mg Fluorogestone Acetate. Implants or sponges were left in situ for 12 d and 500 IU pregnant mares' serum gonadotropin was injected im at the time of removal. Following treatment with Implant H, 96% of ewes were judged to be in estrus at 48 h after implant removal. Fertility of adult ewes and ewe lambs (6 to 7 mo of age at time of breeding) at the synchronized estrus were similar after implant H or sponge treatment, but litter size was higher (P less than .05) for adult ewes treated with sponges. The percentages of adult ewes marked by rams within 60 h after removal of silastic implants or intravaginal sponges were similar. There was a tendency for ewe lambs to be marked later than adult ewes and for adult ewes treated with Implant S1 and Implant S2 to be marked earlier than ewes treated with Implant S3 or sponges. Higher percentages (P less than .05) of adult ewes and ewe lambs lambed to breeding at the synchronized estrus after treatment with Implant S2 or Implant S3, respectively, than after treatment with Implants S2 or sponges.     

多浪羊一年两产繁育技术的初步研究

采用孕酮阴道栓和孕马血清促性腺激素相结合的方法对秋季空怀和春季早期断奶的多浪羊母羊进行同期发情处理,探讨综合性频密繁育技术。结果表明:在一年两产的频密繁育过程中,秋季空怀母羊与春季早期断奶母羊同期发情率无显著性差异(97.2%vs 96.0%)(P>0.05);分别对上述同期发情的母羊实施人工授精,受胎率有显著性差异(82.9%vs 54.0%)(P<0.05);平均产羔数(1.4 vs1.3)及产双羔母羊比率(37.9%vs 26.7%)均无显著性差异(P>0.05)。试验证明,对多浪羊母羊实施频密繁育技术处理,可以实现一年两次产羔,提高母羊的生产性能。     

Effect of sexed semen,puberty and breeding ages on fertility of Holstein dairy heifers treated with double Ovsynch protocol

The objective of this study was to evaluate the fertility of sexed semen compared with conventional semen with regard to the puberty and breeding ages of Holstein dairy heifers subjected to double Ovsynch protocol with fixed time of artificial insemination. A total of 468 Holstein heifers were divided into two groups. The first group was 122 dairy heifers inseminated via conventional semen, while the second group was 346 heifers inseminated with sexed semen. The puberty and breeding ages of heifers were determined from the farm records. Estrus was synchronized using the double Ovsynch protocol. Numbers were estimated for pregnancy at 40 and 60 days post insemination, embryonic loss, and abortion. The results revealed that the heifers inseminated with sexed semen had a significantly lower first-service pregnancy rate (51.45%) than those inseminated with conventional semen (61.47%). Heifers achieving puberty before 350 days old had a higher pregnancy rate. Embryonic losses and abortion rates did not differ between the two types of semen. Holstein heifers subjected to Ovsynch protocol with sexed semen had an acceptable first-insemination pregnancy rate. Even the applications of sexed semen reduce the reproductive fertility and pregnancy rate in Holstein heifers.

     

Fertility after different artificial insemination methods using a synthetic semen extender in sheep

The present study aimed to investigate the fertility of ewes artificially inseminated with three different methods using a synthetic semen extender, AndroMed. The three methods of artificial insemination (AI) were cervical AI with fresh-diluted or frozen-diluted semen at observed estrus, and an intrauterine AI with frozen-thawed semen. A total of 80 ewes were treated with a controlled internal drug release (CIDR) containing 0.3 g progesterone per device for 12 days. In Experiment 1 (26 Suffolk ewes), superovulation was induced with 20 mg follicle-stimulating hormone and 250 IU equine chorionic gonadotropin (eCG) two days and one day before CIDR removal, respectively, during the non-breeding season. In Experiment 2 (54 Suffolk and Suffolk crossbred ewes), an intramuscular injection of 500 IU eCG was administered one day before CIDR removal to synchronize estrus and ovulation during the breeding season. In Experiment 1, fresh-diluted or frozen-thawed semen was deposited into the cervical orifice after estrus detection, and an intrauterine AI with frozen-thawed semen was performed by laparoscopy at a fixed-time basis without estrus detection. Embryos were recovered by uterine flushing 6 days after AI, and the rates of recovered, fertilized (cleaved) ova and embryos at the morula or blastocyst stage were compared among the three AI methods. In Experiment 2, the pregnancy rates after the three AI methods were compared. In Experiment 1, the rates of recovered ova were not significantly different among the three AI methods (52.5-56.7%). The rate of fertilized ova (81.0%) by laparoscopic AI with frozen-thawed semen was significantly higher compared with cervical AI of fresh-diluted (25.5%) or frozen-thawed (3.5%) semen, but the rate of embryos at the morula or blastocyst stage (17.6%) was significantly lower than that of the cervical AI with fresh-diluted semen (69.2%). The rates of ewes yielding fertilized ova were not significantly different among the three groups (44.4, 11.1 and 62.5% for cervical AI with fresh-diluted and frozen-thawed semen and intrauterine AI with frozen-thawed semen). In Experiment 2, the pregnancy rate of ewes intrauterinally inseminated with frozen-thawed semen (72.2%) was significantly higher than those of ewes inseminated cervically with fresh-diluted (5.5%) or frozen-thawed (0.0%) semen. The present results showed that acceptable fertilization and pregnancy rates could be obtained by an intrauterine AI with frozen-thawed semen using a synthetic semen extender (AndroMed), but not sufficient by the cervical AI with either fresh or frozen semen.     

Improvement by ergonovine of sperm transport, fertilization and pregnancy rates in ewes in natural or prostaglandin-induced estrus

Eight experiments were conducted with 451 ewes to test effects of ergonovine, prostaglandin F2 alpha (PGF2 alpha) and phenylephrine on sperm transport and fertility. In most experiments, ewes were mated at estrus and necropsied 2 or 3 h later. Sperm were flushed from the oviducts, uterus and anterior, middle and posterior thirds of the cervix and counted. Various doses of PGF2 alpha or phenylephrine given im at mating caused no significant increase in sperm numbers in any segment of the tract 2 h later. Three different dose levels of ergonovine were given im to ewes in natural estrus 1 h after mating and ewes were necropsied 3 h after mating. Doses of .2 and 1.0 mg were ineffective, but .5 mg increased sperm numbers about 10-fold in the oviducts and uterus. When given im at the time of artificial insemination, .6 mg of ergonovine increased the fertilization rate at 3 d from 5/25 in control ewes to 12/25 (P less than .05). In three experiments with ewes in PGF2 alpha-induced estrus, .6 mg of ergonovine increased sperm numbers in the cervix and uterus at 3 h after mating and in the uterus and oviducts at 23 h, near ovulation. Other ewes were artificially inseminated in the external cervical os and one-half of the ewes were given .6 mg of ergonovine im; ewes not returning to estrus were laparotomized at 22 to 26 d and embryos removed. After insemination during natural estrus with .2 ml of semen, pregnancy rates were 14/25 for control ewes and 15/25 for ergonovine-treated ewes; after insemination during natural estrus with .1 ml of semen, 6/35 and 18/35 (P less than .005); after insemination during PGF2 alpha-induced estrus with .2 ml of semen, 7/60 and 12/60. Fertilization and pregnancy rates combined were 32/145 (22%) for all control ewes and 57/145 (39%) for ergonovine-treated ewes (P less than .005).     

Potential treatments for anestrus in gilts and sows

Pregnant mares' serum gonadotrophin (400 IU) combined with human chorionic gonadotrophin (200 IU) was administered to anestrous gilts (n=31) and sows (n=20) in commercial herds. Two-thirds of the treated animals were mated successfully within seven days and, although no control animals were included, the response indicated that this hormone combination would be useful in herds with anestrous problems. A second experiment was conducted to evaluate the occurrence of estrus and/or ovulations in prepuberal gilts (n=eight/treatment) following injection with pregnant mares' serum gonadotrophin/human chorionic gonadotrophin or other hormones that might stimulate ovarian activity. The pregnant mares' serum gonadotrophin/human chorionic gonadotrophin combination and follicle-stimulating hormone produced estrus within ten days of injection in at least half of the treated gilts but the response was lower with gonadotrophin-releasing hormone and a prostaglandin analogue. Combinations of human chorionic gonadotrophin with small amounts of estradiol benzoate stimulated estrus and ovulation in most of the treated gilts.     

Achieving canine pregnancy by using frozen or chilled extended semen

Successful artificial insemination in the dog requires good timing of the insemination, skilled collection and handling of the semen, and mastering of insemination techniques. The bitch should be inseminated late in estrus. The insemination dose should contain at least 150 to 200 x 10(6) spermatozoa. Fresh semen can be inseminated vaginally, whereas frozen-thawed semen should be inseminated into the uterus. Pregnancy rates of 84% with fresh semen and 69% with frozen semen are reported.     

Greater participation by veterinarians in the reproductive management of dairy cattle

A program involving greater veterinary participation in detection of estrus and artificial insemination of cattle was evaluated in a 700-cow dairy herd from January 1987 through August 1988. Previous reproductive performance was below normal. First-service pregnancy rate from artificial insemination was 42%, and mean number of nonpregnant days for the cows was 120. Between postpartum days 55 and 62, all cows with functional corpus luteum assessed by rectal palpation were administered prostaglandin each Monday morning. Return visits were made to the herd each Thursday and Friday to observe cows and to inseminate those in estrus. On the other 5 days of the week, the owner or his employees inseminated all cows in estrus. The first-service pregnancy rate for 842 cows observed in estrus and inseminated by the veterinarian was 59%. The pregnancy rate for cows inseminated by the owner and his employees increased from 42% to 50%. The mean number of nonpregnant days for all 700 cows decreased from 120 to 98 days, resulting in approximately $46,000 of increased income for the dairyman or approximately a 4 to 1 return on investment in veterinary service. Results indicate that veterinarians could improve herd reproductive performance and solve chronic herd breeding problems by more actively participating with their clients in estrus detection and artificial insemination programs in cattle. The program allows practicing veterinarians an opportunity to observe cows for estrous behavior, establish their own pregnancy rate data, demonstrate to owners the importance of observing primary signs of estrus, and teach expert artificial insemination techniques.     

Serum progesterone determination as an aid for pregnancy diagnosis in goats bred out of season

Nubian does (n = 12) were bred by artificial insemination after induction of estrus with medroxyprogesterone acetate impregnated vaginal sponges and pregnant mare serum gonadotrophin injections during the anestrous season. Pregnancy status was predicted from serum samples collected 21 days following the last breeding and analyzed using 1) a commercial bovine milk progesterone enzyme immunoassay test (EIA), and 2) a radioimmunoassay progesterone (RIA) test. Both tests detected nonpregnancy (EIA 100%, RIA 80%) more accurately than pregnancy (EIA 66%, RIA 75%). Commercial bovine progesterone EIA kits have potential as rapid, inexpensive screening tests for nonpregnant does bred out of season.