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PubMed1998

Artificial insemination in Callithrix jacchus using fresh or cryopreserved sperm.

Assisted reproductive techniques are needed urgently to facilitate the captive breeding of many New World primate species which are endangered in the wild and to assist the effective genetic management of small colonies. A protocol was devised for artificial insemination in the common marmoset, Callithrix jacchus, using ejaculated sperm obtained by vaginal washing after copulation. A double insemination protocol was employed, with the first insemination taking place the day before ovulation was expected to occur and the second 48 h later. All six females inseminated with fresh ejaculated sperm became pregnant, delivering a total of 16 offspring at term. The gestation lengths and litter sizes were not statistically different from those observed in pregnancies following natural mating. The insemination protocol was adapted for use with cryopreserved ejaculated sperm by including an additional insemination on the day of expected ovulation, to take into account differences in the capacitation time of frozen-thawed sperm compared to fresh sperm. Three out of six females inseminated according to this triple insemination schedule, conceived, although one female subsequently resorbed twin foetuses approximately 100 days later. The remaining two pregnant females delivered four babies at term, one singleton and one set of triplets. In the final group, six females were inseminated with low doses of cryopreserved epididymal sperm using the same triple insemination protocol used for frozen-thawed ejaculated sperm. One female conceived, delivering triplets.

Animals↗
PubMed2006

Porcine field fertility with two different insemination doses and the effect of sperm morphology.

In swine artificial insemination, several dose regimens are applied, ranging from 1.5 x 10(9) to 6.0 x 10(9) spermatozoa per intra-cervical insemination dose. A lower sperm dose is more profitable for artificial insemination centres and offers a more effective use of superior boars. To evaluate fertility, 50 boars were used for a total of 10 773 homospermic first inseminations at a dose of 2 billion spermatozoa. In addition, 96 boars were used at a dose of 3 billion spermatozoa for 34 789 homospermic first inseminations. Fertility was determined by a 60-day non-return rate (NR%) of first inseminations. Litter size was registered by total number of piglets born separately in primiparous and multiparous farrowings. On average, a sow was inseminated 1.5 times. A significant decrease was observed in all three fertility parameters (NR%, litter size of both primiparous and multiparous farrowings) with a dose of 2 billion spermatozoa compared with a dose of 3 billion spermatozoa. The NR% was 75.8% and 84.0% (p < 0.001), the mean litter size of primiparous farrowings 10.1 and 10.7 (p < 0.001) and the mean litter size of multiparous farrowings 11.7 and 12.1 (p < 0.001) for 2 and 3 billion spermatozoa/dose, respectively. The proportion of normal spermatozoa in the sperm morphology analysis correlated significantly with NR% in both insemination regimens: p < 0.001, r = 0.604 and p < 0.05, r = 0.223 for 2 and 3 billion spermatozoa/dose, respectively. These results confirm that quantity can at least partly compensate for poor sperm quality. When the boars with <70% normal spermatozoa in the morphology evaluation were excluded from the data there were no correlation between the sperm morphology and NR%. However, the difference between the NR% and litter size remained statistically significant (p < 0.001) in favour for the bigger insemination dose. In conclusion, a decrease in sperm dose from 3 to 2 billion spermatozoa on commercial farms will severely decrease prolificacy at least under field conditions, where a sow is inseminated an average of 1.5 times/heat, and the semen is typically used within 3 days after collection. We recommend that under commercial circumstances the homospermic semen doses contain no <3 billion spermatozoa/dose.

Animals↗
PubMed1985

Effect of insemination regimen on embryo production in superovulated cows.

Three experiments tested the effects of six insemination regimens on embryo production in superovulated cows. One, two or three inseminations with one unit of semen at each time produced the same percentage fertilised (74, 68 and 74 per cent, P = 0.673) and the same number of fertilised embryos (8.2, 6.3 and 9.1, P = 0.136). However, the one and two inseminations group had less transferable (P = 0.008) and total (P = 0.051) embryos (3.9/9.6 and 3.9/8.9) than the three inseminations group (6.8/13.2). The percentage transferable remained the same (42, 45 and 58 per cent, P = 0.161). When two units of semen were used at the first or middle insemination and one, two and three inseminations were compared, the percentage fertilised (65, 77 and 77 per cent, P = 0.082) and the number fertilised (7.0, 7.4 and 8.6, P = 0.565) were again the same but the number (P = 0.047) and percentage transferable (P = 0.000) increased between the one and two inseminations (3.8 vs 5.7 and 30 per cent vs 54 per cent). The increase in transferable embryos with multiple inseminations could not be explained physiologically, but is of concern since transferable embryos are the "sales product' of superovulation. Two inseminations with one unit of semen was as effective as two inseminations with three units of semen, in terms of percentage fertilised (68 and 70 per cent, P = 0.762), number fertilised (10.3 and 8.3, P = 0.582), transferable embryos (6.7 and 5.7 P = 0.532), percentage transferable (44 and 46 per cent, P = 0.737) and total embryos recovered (14.8 and 12.7, P = 0.54).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Influence of the number of days spent training in an abattoir with access to live cows on the efficiency of do-it-yourself artificial insemination.

Data relating to 35,389 inseminations carried out in the first three years after inseminators were trained were collected by postal questionnaire from 94 do-it-yourself (DIY) artificial inseminators in the UK. The mean calving rate from 14,528 inseminations they carried out on 92 farms in the first year after they were trained was 59.4 per cent (range 5 to 92 per cent). In the second year the mean calving rate from 11,515 inseminations by 64 inseminators was 62.3 per cent (range 33 to 88 per cent), and in the third year the mean calving rate from 9346 inseminations by 49 inseminators was 64.6 per cent (range 41 to 92 per cent). There was an increase of 5.2 per cent in the mean calving rate over the three years with an overall mean calving rate of 61.5 per cent. Each trainee carried out an average of 376 inseminations (range 20 to 800) during the three years. Thirteen instructors were responsible for the tuition and the average time the trainees spent in an abattoir with access to live cows was 2.88 days, with a range from none to five days. For the trainees who spent up to three days training in an abattoir there was an increase of 5.9 per cent in the calving rate they achieved in their first year for every day they spent training with access to live cows (P < 0.005), but there were no significant effects on the outcome of their inseminations in their second or third years.

Abattoirs↗
PubMed2000

Intrauterine and intravaginal insemination with frozen canine semen using an extender consisting of orvus ES paste-supplemented egg yolk tris-fructose citrate.

Our previous report indicated that addition of Orvus ES Paste (OEP) to the extender of frozen canine semen protected acrosomes and maintained sperm motility after thawing. In this study, artificial insemination (AI) using the frozen semen was carried out. The frozen semen was prepared using egg yolk Tris-fructose citrate, and the final concentrations of glycerol and OEP were 7% (v/v) and 0.75% (v/v), respectively. AI was performed during the optimal mating period predicted from the peripheral plasma progesterone level. In intrauterine insemination (IUI), the bitches were laparotomized and 1 x 10(8) spermatozoa were infused into one of the uterine horns. In insemination of non-OEP supplemented semen, 3 x 10(8) spermatozoa were inseminated. In intravaginal insemination (IVI), 10-40 x 10(8) spermatozoa were inseminated. Conception was obtained in nine of 10 bitches (90.0%) that underwent IUI. The number of newborns was from 1 to 7 (mean 3.6 +/- 0.9). The mean ratio of the number of puppies to the number of ovulations in the inseminated uterine horn was 71.8%. The number of puppies did not exceed the number of ovulation in the inseminated uterine horn. Conception using non-OEP supplemented frozen semen was unsuccessful in all four bitches. In IVI, conception was not obtained in any of the six bitches that received insemination of 10 x 10(8) or 40 x 10(8) spermatozoa, but two of three bitches that received insemination of 20 x 10(8) spermatozoa were fertilized. It was shown that a high conception rate can be obtained by IUI using OEP-supplemented frozen canine semen. Developmenmt of a non-surgical method of IUI and a method of freezing canine sperm applicable to IVI is necessary.

Animals↗
PubMed2005

Inseminations at estrus induced by presynchronization before application of synchronized estrus and ovulation.

A controlled field study examined conception rates after 2 timed artificial insemination (TAI) breeding protocols conducted on 2 commercial dairy farms. Estrous cycles in postpartum lactating cows were presynchronized with 2 injections of PGF(2alpha) given 14 d apart (Pre-synch) and then, after 12 d, the standard Ovsynch protocol (injection of GnRH 7 d before and 48 h after an injection of PGF(2alpha), with one TAI at 12 to 16 h after the second GnRH injection) or Heatsynch protocol [injection of GnRH 7 d before an injection of PGF(2alpha), followed 24 h later by 1 mg of estradiol cypionate (ECP) and one TAI 48 h after ECP] was applied. Experimental design allowed artificial insemination to occur anytime after the second Presynch injection and during the designed breeding week when estrus was detected. Of the 1846 first services performed, only 1503 (rate of compliance = 81.4%) were performed according to protocol. Numbers of cows inseminated, logistic-regression adjusted conception rates, and days in milk (DIM) were for inseminations made: 1) during 14 d after first Presynch injection (n = 145; 22.6%; 54 +/- 0.4 DIM); 2) during 12 d after second Presynch injection (n = 727; 33%; 59 +/- 0.2 DIM); 3) during 7 d after the first GnRH injection of Ovsynch or Heatsynch (n = 96; 32.1%; 74 +/- 0.5 DIM); 4) after estrus as part of Heatsynch (n = 212; 44.6%; 76 +/- 0.3 DIM); 4) after TAI as part of Heatsynch (n = 154; 21.1%; 76 +/- 0.4 DIM); 5) after estrus as part of Ovsynch (n = 43; 48.7%; 77 +/- 0.7 DIM); and 6) after TAI as part of Ovsynch (n = 271; 24.4%; 77 +/- 0.3 DIM). Conception rates when AI occurred after one Presynch injection were less than when AI occurred after 2 Presynch injections. Conception rates for those inseminated after either Presynch injection did not differ from those inseminated after combined Heatsynch + Ovsynch. Cows in the Ovsynch and Heatsynch protocols inseminated after estrus during the breeding week had greater conception rates than those receiving the TAI, but overall conception rates did not differ between protocols. Among cows inseminated after detected estrus, conception was greater for cows in the Heatsynch + Ovsynch protocol (77 +/- 0.4 DIM) than for those inseminated after either Presynch injection (54 +/- 0.4 or 59 +/- 0.2 DIM). We concluded that conception rates after Heatsynch and Ovsynch were similar under these experimental conditions, and that delaying first AI improved fertility for cows inseminated after detected estrus.

Animals↗
PubMed1983

Factors affecting reproductive performance of dairy cows first inseminated after five weeks postpartum.

Various factors influencing reproduction of 307 Holstein cows were evaluated. Sources of variation of several measures were estrous certainty, time of day of detected estrus and insemination, method of thawing semen, ease of cervix penetration, presence of clear mucus at insemination, service number, service sire, inseminator, age of cow, maximum ambient temperature on the service date, and milk yield. Interval to first service of older cows was longer than of younger cows and shorter for cows with higher milk yield. Conception rate was higher for inseminations before noon than after noon and tended to be lower at inseminations when milk yield was at the extremes (low or high). Rate of conception was similar for cows whether inseminated at early or later postpartum intervals. More services were required by cows that were inseminated when milk yield was at the extremes (low or high). Fewer days open were associated with fewer total services and younger age at conception. Cows inseminated with semen thawed in hot (65 degrees C, 7 to 10 s) or warm (35 degrees C, 30 s) water conceived earlier postpartum than did those inseminated with semen thawed in the cow. Submitting cows for insemination after detection of standing estrus, mounting activity, or less certain symptoms of estrus had no adverse effect on fertility or days open.

Animals↗
PubMed1988

Impact of site of inseminate deposition and environmental factors that influence reproduction of dairy cattle.

Uterine body and cornual inseminations (n = 2127) were evaluated over a 3-yr period in Holstein and Jersey cattle. For cornual insemination one-half of each semen dose was deposited approximately 2.5 cm into each uterine horn. Conception rate was lower for cervical insemination (39.4%) than uterine body (48.1%) or cornual (49.3%) inseminations. Pregnancy site distribution was equal for both insemination techniques but cervical insemination resulted in 60% right horn pregnancies. Primary housing, service number, inseminator, lactation number, and sire affected conception rate. Older cows were least fertile (31.4%), second service conception rate was lowest (42.6%), and barn housed cattle had a 39.7% conception rate. Days open was affected by primary housing, service number, sire, site of semen placement, and twinning. Twinning increased days open by 10 d. Optimum time for insemination of lactating cows was between 6 and 12 h after the initial observation of estrus. From this study we conclude that shallow cornual insemination is as effective as uterine body insemination, and conception rate is optimized when estrus is positively assessed.

Animals↗
PubMed1976

Effect of semen dose, frequency of insemination, age and productivity of the male on duration and levels of fertility and hatachability in the turkey.

In 3 separate trials, duration and levels of fertility and hatchability were studied in 3 groups of Broad Breasted White turkey hens inseminated on 1, 2 or 3 successive days with 0.030 ml. semen. In the first test, hens in a fourth group were given a single insemination of 0.090 ml. semen. and those in the fifth group received 2 inseminations of 0.045 ml. The semen used in Trial 1, was obtained from males producing different levels of semen, and in Trials 2 and 3 the semen was from males of different age groups. Neither age of the male nor level of semen production appreciably affected duration or levels of fertility in turkey hens. However, duration and level of fertility were slightly better in hens given 2 or 3 inseminations of 0.03 ml. or 2 inseminations of 0.045 ml. of semen on successive days than in comparable hens given a single insemination of 0.030 ml. or 0.090 ml. semen. Hatchability was significantly higher (p = less than .05) in hens inseminated twice with doses of 0.030 ml. as compared with hens inseminated 1 or 3 times with doses of 0.030 ml. In 1 of 2 test years, hatchability in hens inseminated with semen from young males was from 7 to 12 percent greater than for comparable hens inseminated with semen from old males. Semen concentration and percent of normal sperm was generally higher in young males (39 wk.) as compared to older males (89 wk.).

Age Factors↗
PubMed1995

Donor insemination: effects on parents.

OBJECTIVE: To examine the psychosocial effects of donor insemination on couples. DESIGN: Questionnaire survey of couples who had a child by donor insemination at four NSW clinics over a 15-year period. RESULTS: Forty-seven per cent of couples thought their marriage had improved, while 3% thought their marriage had deteriorated as a result of having a child by donor insemination. Seventy-six per cent felt it had a positive personal effect and almost all couples had no regrets about having a child this way. Over 90% of respondents felt very close to these children. In those who also had children not conceived by donor insemination (60 couples), men were significantly closer to their children by donor insemination than to their "other" children (P < 0.001). There was a significant sex difference in perceptions of the child's resemblance (P < 0.0001): 61% of women thought their child conceived by donor insemination resembled their partner, while 89% of men thought the child resembled their partner. Twenty-one per cent of couples were concerned about having to tell the child about donor insemination. CONCLUSION: Donor insemination can have positive psychosocial effects on couples and close relationships exist between the parents and their children conceived by donor insemination. The concern about the physical appearance of children conceived by donor insemination can be allayed by our finding that the majority of couples see a resemblance between the child and their partner.

Adult↗
PubMed1997

FDA approved? A critique of the artificial insemination industry in the United States.

Artificial insemination by donor is becoming an increasingly popular means to achieving parenthood. While the majority of couples use artificial insemination to overcome fertility problems, many recipients use artificial insemination to avoid passing a genetic disease to their children. However, case studies reveal the inherent dangers of artificial insemination, namely the lack of proper screening methods to avoid passing genetic diseases to children born by artificial insemination. State-by-state regulation, federal guidelines, and private adjudication have all proven to be inadequate methods of regulating the artificial insemination industry. Ginsberg proposes federal regulation as the only means of achieving a safe artificial insemination industry. The proposed federal regulation would include better genetic screening, a more efficient national sperm donor system, and limited disclosure to recipients of artificial insemination and their children. These measures would help to ensure that couples using artificial insemination get what they expect--healthy sperm, a safe artificial insemination process, and ultimately, a healthy child.

Confidentiality↗
PubMed1991

Impact of a second insemination on the results of an in vitro fertilization-embryo transfer (IVF-ET) program.

In an attempt to increase the fertilization and pregnancy rates in our program, a second insemination was carried out when the first insemination yielded fewer than two fertilized oocytes. One hundred eighty consecutive patients were studied retrospectively and thirty-four required second insemination, 35% of them by donor semen. Fifty-five and nine-tenths percent of the patients had at least one fertilized oocyte for embryo transfer, but only 21.9% of the oocytes exposed to a second insemination were fertilized. No pregnancy resulted from the transfer of oocytes fertilized by the second insemination. There were no significant correlations between the success of fertilization after a second insemination and the number of oocytes retrieved, the protocol for the induction of superovulation, or the age of the female patient. Considering that the first insemination was done at a variable time after oocyte retrieval to allow oocyte maturation, we expected all oocytes to be mature at the time of first insemination and we considered the possibility of delayed fertilization as negligible since second insemination was done at least 24-30 hr after oocyte retrieval. Even though a second insemination provides further hope for the patient, by yielding additional fertilized oocytes for embryo transfer, its main value is that it may provide additional information about male fertility.

Adult↗
PubMed1988

Effect of insemination timing on the fertilizing capacity of frozen/thawed equine spermatozoa.

A breeding trial was conducted to evaluate the effect of insemination timing on the fertility of mares bred with frozen/thawed equine semen. One stallion and 60 reproductively sound, estrous-synchronized mares were included in the study. Mares were assigned to one of three groups (n = 20): 1) insemination with fresh semen every other day during estrus from detection of a 35-mm follicle until ovulation, 2) insemination with frozen/thawed semen every day during estrus from detection of a 35-mm follicle until ovulation or 3) insemination with frozen/thawed semen once, within 6 h after ovulation. Single-cycle 18-d pregnancy rates resulting from insemination with fresh semen (70%), preovulation insemination with frozen/thawed semen (60%) and postovulation insemination with frozen/thawed semen (55%) were not different (P > 0.05). Possibly, equivalent pregnancy rates could be achieved with frozen/thawed semen using either daily inseminations until ovulation occurs or frequent ovarian palpations with a single post-ovulation insemination. Further studies regarding the effect of insemination timing on stallion fertility are needed since the present investigation included only one stallion and a small number of mares.

Journal Article↗
PubMed1992

Compaction rate of in vitro fertilized bovine embryos related to the interval from insemination to first cleavage.

A study was conducted on early cleavage divisions and timing of compaction in bovine preimplantation-stage embryos. Zygotes were produced using conventional in vitro maturation and fertilization procedures. Twenty hours post insemination, the zygotes were denuded and cultured with oviduct epithelial cells in B2 medium + 10% estrous cow serum. Starting at 24 hours post insemination, the embryos (n=657) were evaluated every 6 hours and then were put into different co-culture drops according to their cell number. Starting from 78 hours post insemination, the cleavage rate was evaluated every 12 hours. Embryos were stained with Hoechst 33342 at the compacted morula stage or when they were degenerated, at 162 hours post insemination. Developmentally capable embryos were characterized by a rapid cleavage rate in the first 3 cell cycles and by an extended 8- to 16-cell stage. Peak concentrations of 2-, 4-, 8- and 16-cell stages emerged at 36, 42, 60 and 102 hours post insemination, respectively. Compaction did not occur until 126 hours post insemination. The rate of compaction was significantly higher in embryos that were at the 2-cell stage before or at 36 hours post insemination (P < 0.05). The mean cell numbers of compacted morulae that were identified at 126 and 138 hours post insemination were 30.9 +/- 6.8 and 31.6 +/- 7.7, respectively. These results indicate that developmentally capable bovine embryos reach the 2-cell stage at 36 hours post insemination, and that they become compacted at the 32-cell stage, which usually occurs between 126 and 138 hours post insemination.

Journal Article↗
PubMed1996

Effects of administering progesterone at selected intervals after insemination of synchronized heifers on pregnancy rates and resynchronization of returns to service.

In 3 separate trials at 2 locations, dairy heifers (n = 396) were treated with a Controlled Internal Drug Release (CIDR) progesterone device for 9 d. On Day 7 of CIDR treatment, all heifers were injected with PGF(2alpha). Synchronized estruses were detected using a tailpaint and chalk (TPC) scoring system. An animal's tailhead was painted at device insertion, and this strip was covered with a contrasting color of chalk at device removal. Over all trials, 85.1% of the heifers were detected in estrus and were inseminated at 48 or 72 hours after CIDR removal. These synchronized and inseminated heifers were divided into the following treatment groups: 1) untreated controls, receiving no further treatment (n = 138); 2) post-insemination progesterone supplementation with a new (n = 59) or used (n = 29) CIDR device for Days 1 to 8 or 2 to 9, respectively, following insemination; or 3) resynchronization of return to service with a used CIDR device for Days 17 to 22 after insemination (n = 112). The pregnancy rate to first insemination in the control and resynchronized groups (Groups 1 and 3) was 46.4%, but decreased to 18.2% with the post-insemination progesterone supplementation. Resynchronization of returns to service (estrus detected 1 to 4 d following removal of second CIDR) occurred in 58.9% of all nonpregnant heifers in Group 3. In summary, CIDR devices used in conjunction with PGF(2alpha) effectively synchronize estrus in dairy heifers. Progesterone supplementation within 2 d of first insemination for 7 d suppressed fertility. Used CIDR devices inserted for Days 17 to 22 after first insemination resynchronized heifers not pregnant to first insemination.

Journal Article↗
PubMed1997

Increased incidence of preeclampsia in women conceiving by intrauterine insemination with donor versus partner sperm for treatment of primary infertility.

OBJECTIVE: Reports suggest that there is an increased incidence of preeclampsia after a previously normal pregnancy if there is a change in paternity. We hypothesize that there is a higher incidence of preeclampsia (proteinuric hypertension) in women conceiving by intrauterine insemination with donor sperm versus intrauterine insemination with partner sperm. STUDY DESIGN: This was a retrospective cohort study. In women with primary infertility all pregnancies achieved by either partner or donor intrauterine insemination carried to birth of a fetus (> 20 weeks) were identified. The medical records were examined for the maternal and pregnancy outcome data. The relative risk and 95% confidence interval were calculated for the risk of preeclampsia. The baseline data were compared with t tests, chi 2 analysis and Fisher's exact test where appropriate. RESULTS: Forty-four patients in the partner intrauterine insemination group and 37 in the donor insemination group were identified as having primary infertility. Three cases of mild preeclampsia were found in the partner insemination program and nine cases of preeclampsia (five severe, four mild) in the donor insemination program (relative risk 1.85, 95% confidence interval 1.20 to 2.85). CONCLUSIONS: There is a higher incidence of preeclampsia in women conceiving by intrauterine insemination with washed donor sperm compared with intrauterine insemination with washed partner sperm. This supports, indirectly, an immunologic basis for preeclampsia. The antigenic factor would appear to be located on the sperm as opposed to the seminal fluid itself.

Cesarean Section↗
PubMed1992

Intrauterine insemination: critical analysis of a therapeutic procedure.

Donor intrauterine insemination with washed spermatozoa (fresh semen) was performed in 36 women (63 cycles) whose husbands had azoospermia due to primary or secondary testicular failure. Simultaneously a control group of 76 couples (156 cycles) with proven fertility, who had recently discontinued mechanical non-hormonal contraception, were encouraged to have sexual intercourse during the fertile period. The age of the women was similar in both groups and the timing criteria were also similar. The pregnancy rate per woman was 50% in the donor insemination group and 47.4% in the control group (difference not significant). The pregnancy rate per cycle was 28.6% in the artificial insemination group and 23.1% in the control, natural insemination group (difference not significant). The number of artificial or natural insemination cycles required to achieve pregnancy was similar in the study and control groups. This study suggests that when the inseminating spermatozoa and female partner are normal, as occurs in the donor insemination group, intrauterine insemination is as efficient as natural insemination in achieving pregnancy but is not more successful.

Adult↗
PubMed2001

Effect of time of insemination on number of accessory sperm, fertilization rate, and embryo quality in nonlactating dairy cattle.

Two experiments were conducted to determine the effect of insemination time on number of accessory sperm per embryo (ovum), fertilization rate, and embryo quality. Semen was collected from three fertile Holstein bulls and cryopreserved in egg yolk-citrate-glycerol. In experiment 1, cows were continuously monitored for behavioral estrus by the HeatWatch estrous detection system and were artificially inseminated (AI) with one 0.5-ml straw (25 x 10(6) sperm) at the onset of estrus (AI 0 h), 12 h after onset (AI 12 h), or received natural service at 0 h (Nat 0 h) from one of three bulls. From 150 inseminations, 115 embryos and ova (AI 0 h: n = 39; AI 12 h: n = 39; Nat 0 h: n = 37) were recovered 6 or 7 d after insemination. Fertilization rates differed between treatments (AI 0 h: 67%; AI 12 h: 79%; Nat 0 h: 98%). Median accessory sperm per embryo (ovum) also differed (AI 0 h: 1; AI 12 h: 10; and Nat 0 h: 27) and paralleled the fertilization rate. Embryo quality was not affected by insemination time or natural service. In experiment 2, cows received AI at 0, 12, or 24 h (AI 24 h) after the onset of estrus as determined by HeatWatch. From 154 inseminations, 117 embryos and ova (AI 0 h: n = 39; AI 12 h: n = 39; AI 24 h: n = 39) were recovered 6 or 7 d after insemination. Fertilization rates did not differ in experiment 2 (AI 0 h: 66%; AI 12 h: 74%; AI 24 h: 82%); however, a trend toward a higher fertilization rate accompanied AI 24 h. Median accessory sperm values increased from AI 0 h (1) to AI 24 h (4). Embryo quality declined with AI at increasing intervals after onset of estrus, as percentages of excellent and good, fair and poor, and degenerate embryos were as follows: 77, 15, 8; 52, 38, 10; and 47, 19, 34 for the 0-, 12-, and 24-h inseminations, respectively. Results indicate AI 12 h after the onset of estrus provides a compromise between potential fertilization failure (AI 0 h) and embryo failure (AI 24 h), despite increased accessory sperm per embryo (ovum) after AI 24 h. Artificial insemination 12 h after onset of estrus should optimize fertility of dairy cattle through an acceptable fertilization rate, number of accessory sperm per embryo, and desirable embryo quality.

Animals↗