• Biomedical Science Letters
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• v.9 no.1
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• pp.29-36
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• 2003

Progesterone levels in the blood plasma or skim milk of cows are considered to be very useful indicator fur the detection of estrus cycle and early pregnancy diagnosis. During 13 to 14 days after estrus the level of progesterone in plasma or skim milk were not different between the inseminated arid non-inseminated cows. In the pregnant cows the peak level of progesterone reached on 14th day after artificial insemination (AI), but in the absence of conceptus the level declines after the 14th day slowly, and then very rapidly towards the basal level after the 17th day. This low level persists about 4 days, including those of estrus and ovulation a highly characteristic pattern which differs so markedly from that in the pregnant cows. Progesterone levels in blood plasma or skim milk can provided a reliable diagnosis of early pregnancy and monitoring ovarian activity in cows. The mean $\pm$ standard deviation of milk urea nitrogen(MUN) and protein concentration in the cows at 9 herds were 17.7$\pm$2.35 mg/dL and 3.2$\pm$0.17%, respectively. The days of nonpregnant after parturition was shorter in the cows in which the lower level of MUN than higher level of MUN concentration.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.53-53
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• 2001

Two trials were conducted in a commercial dairy farm on heifer synchronization with PGF$_2$ $\alpha$. Animals showing estrus following the first injection were bred and animals not showing estrus were given the second injection 10 days later. In the first trial, the injection sites were rump and rump. In the second trial, the injection sites were rump and shoulder. Estrous detection was peformed 24 h after injection. Animals were bred by the same technician. In the first trial, the response rate for the first injection was 51.4% and the subsequent pregnancy rate of these animals was 60.0%. The response rate in the second injection was 57.1% and the pregnancy rate was 50.0%. In the second trial, the response rate in the first injection on the rump was 48.7% and the subsequent pregnancy rate was 70.6%. The second injection was given on the shoulder and the response rate was 60.0% and the subsequent pregnancy rate was 25.0%. The data suggests that the site of PGF2 $\alpha$ administration was critical to achieve success in estrous synchronization and pregnancy rates.

• Journal of Embryo Transfer
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• v.1 no.1
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• pp.35-49
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• 1986

Recipients are an integral part of embryo transfer and they are expensive to maintain as a good recipient. Recipient management is one of the most important components in a successful embryo transfer program. Management includes selection and subsequent care of the animals. A good recipient is basically on "open" cows or heffers whose reproductive tract is capable of receiving one or two embryos and incubating it to term. Potential recipients should be always be healthy and cycling normally ranging from 18 to 23 days. A thorough veterinary examination is recommended for candidate of recipients and cattle for questionable health should be eliminated from the recipient herd. Age and size of recipients are particularly important considerations when heifers are used, because of most embryos available for transfer are from large dams and sires. Body condition can influence a recipient's production, reproduction and health. Obese and underconditioned cattle should be avoided for use. Transfer of fresh embryos especially requires precise synchronization of donors and recipients. For estrus synchronization, PGF$_2$$\alpha$ is injected twice 10 to 12 days apart and short4erm progestagen treatment is applied to potential recipient cattle by coil into vagina (PRID) or ear implant (Synchro-Mate-B). The highest pregnancy results are achieved in recipients at exact synchrony with donors or 12 to 24 hr earlier than donors. Estrus detection is a major factor in breeding efficiency. High accuracy can be achieved by use of heat mount detection alds or by obserbing cattle for 30-minute peroids 3 times daily. Assay progesterone in milk can be used to discrIminate between pregnant and nonprenant recipients. Rectal palpation on day 35 to 70 after is an accurate and safe method of pregnancy diagnosis. Embryonic mortality in recipients may be associated with factors such as high environmental temperature and nutritional or lactational stress in early lactation period. Achievement of short calving interval requires concentrated management activity during the first 90 days following calving. Acceptable candidate for a recipient should be routinely vaccinated for infectious diseases. Proper nutritional programs according to NRC requirements and body condition scoring system for recipient cattles are vital to the ultimate success of an embryo transfer program.r program.

• Animal Bioscience
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• v.36 no.4
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• pp.591-600
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• 2023

Objective: We aimed to evaluate the efficacy of a modified Double-Ovsynch protocol vs artificial insemination following estrus detection (AIED) for the enhancement of reproductive performance in Hanwoo cattle. Methods: Four hundred twelve Hanwoo cows were allocated to two treatment groups. The first group of cows were administered gonadotropin releasing hormone (GnRH) on Day 36 (±0.6), prostaglandin F_2α (PGF_2α) on Day 46 (8 to 12 days later), and GnRH on Day 49, which was followed by Ovsynch, consisting of an injection of GnRH on Day 56, PGF_2α on Day 63, and GnRH 56 h and timed AI (TAI) 16 h later (modified Double-Ovsynch group, n = 203). The second group of cows underwent AIED (AIED group, n = 209) and were designated as controls. Results: The pregnancy per AI 60 days after the first AI was higher in the modified Double-Ovsynch (68.5%) than in the AIED (56.5%) group, resulting in a higher probability of pregnancy per AI (odds ratio: 1.68, p<0.05). Moreover, cows in the modified Double-Ovsynch group were more likely (hazard ratio: 1.28, p<0.05) to be pregnant by 150 days after calving than cows in the AIED group, and this difference was associated with a lower mean number of AIs per conception (1.27 vs 1.39, p<0.05) and a shorter median interval between calving and pregnancy (72 vs 78 days, p<0.1). Conclusion: The modified Double-Ovsynch protocol, adjusted according to the herd visit schedule, can be readily used to increase the pregnancy per AI following the first AI and to shorten the interval between calving and pregnancy in beef herds.

• Korean Journal of Agricultural Science
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• v.37 no.3
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• pp.393-398
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• 2010

Early pregnancy diagnosis of bovine is an essential component for efficient reproductive plan in farms because long term of non-pregnancy results in economic losses by failure of offspring production and low milk yield in dairy cattle. The major steroid hormones related with reproduction are known to be progesterone and estrogen in bovine pregnancy. To evaluate detection level of hormones in milk, plasma and milk progestrone and estrogen of Holstein cows was analyzed during artificial insemination (AI) and embryo transfer (ET). Progesterone concentration at 21 days postestrus was significantly different in plasma and milk between pregnant and non-pregnant cows. Estrogen concentration at estrus was higher in pregnant recipients than that in non-pregnant recipients. To analyze correlation between hormone levels and conception rates in Holstein, the conception and return rates were checked following AI, and the returned cows were on the track of pregnancy after consecutive AI. Pregnant cows following first AI were considered as high conception group while pregnant cows following third AI were rated as low conception group. Proportion of high and low conception groups in this study was 78.2% and 9.1%, respectively. Hormone analysis indicated that high conception group had higher estrogen level during estrus than low conception group ($26.45{\pm}3.32$ vs $19.017{\pm}2.97$). Progesterone level was not different between high and low conception groups during estrus but increased significantly after 21 days postestrus (21 day: $4.95{\pm}1.12$ vs $0.95{\pm}0.23$, 35 day: $12.47{\pm}3.82$ vs $2.41{\pm}1.21$). In conclusion, the pattern of progesterone and estrogen secretion in Holstein milk samples could be a good candidate for early pregnancy detection and selection of recipients during ET.

• Korean Journal of Veterinary Research
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• v.34 no.4
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• pp.881-890
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• 1994

Skim milk progesterone($P_4$) profiles in 74 dairy cows were determind to monitor postpartum ovarian activity by radioimmunoassay. Milk samples were collected from each cow every 5 days from 10 to 90 days postpartum. Signs of estrus were observed twice daily, and status of the ovaries and uterus were examined every 10 days by rectal palpation. Results are summarized as follows: 1. Cows were categorized into five types by the change of skim milk $P_4$ profiles; Type I(normal) : Cyclic changes of skim milk $P_4$ profiles appeared within 20 days postpartum(12 cows, 16.2%), Type II(cycle delayed) : Cyclic changes of skim milk $P_4$ profiles appeared from 21 to 60 days postpartum(39 cows, 52.7%), Type III(cycle ceased with low $P_4$) : Onset of the estrous cycle within 20 days postpartum but ceased later with low levels of $P_4$ (7cows, 9.5%), Type IV(cycle ceased with high $P_4$) : Onset of the estrous cycle within 20 days postpartum but ceased later with high levels(>3.0 ng/ml) of skim milk $P_4$ (4 cows, 5.4%), Type V(acyclicity) : Skim milk $P_4$ concentration remained low(<1.0 ng/ml) until 80 days postpartum(12 cows, 16.2%). 2. Out of the 17 cows classified as the Type III and Type V by skim milk $P_4$ profiles, 13 cows had inactive ovaries and remaining 6 cows had single or multiple follicular cysts in their ovaries by rectal palpation. All 4 cows of Type IV had a persistent corpus luteum in their ovaries. 3. Approximately eighty percent of the cows had begun ovarian activity by 60 days postpartum and 90.6% by 90 days by skim milk $P_4$ profiles, but only 39.2% by 60 days and 71.7% by 90 days had shown visible estrus signs. The mean days from parturition to the first, second and third ovulations determined by skim milk $P_4$ profiles was $28.0{\pm}11.0$, $46.4{\pm}13.3$ and $66.4{\pm}11.5$ days and the visible estrus signs were 9.3%, 38.1%, and 48.6%, respectively. The mean days from parturition to the first visible estrus was $57.2{\pm}15.9$ days. These results indicated that milk $P_4$ profile of each Types by radioimmunoassay can be utilized for monitoring postpartum ovarian and would be useful for the early detection of ovarian dysfunction in dairy cow.

• Journal of Embryo Transfer
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• v.21 no.3
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• pp.177-182
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• 2006

This study was conducted to investigate the effects of melengesterol acetate (MGA) and $PGF_{2{\alpha}}$ administrations on serum progesterone level, synchrony of estrus and conception rates in Han-woo. Firstly, ten heifers and one freematin were fed 0.5 mg MGA/day for 14 days in a grain carrier, and after 19 days of MGA feeding, a single injection of 25 mg $PGF_{2{\alpha}}$ were treated. Blood samples were collected to evaluate serum progesterone concentrations from the start of feeding of MGA until the end of feeding and subsequent estrous detection and artificial insemination (AI) at 3 days intervals, and on days of $PGF_{2{\alpha}}$ injection, estrous detection, AI, and 15th and 60th days after AI. The level of progesterone in the blood began to increase from 7 days after MGA feeding, and 9 days after feeding it became 5.4 ng/ml and maintained that level thereafter. On the 33th day when the $PGF_{2{\alpha}}$ was injected, it reached the peak level of 7.6 ng/ml. However, 2-3 days after $PGF_{2{\alpha}}$ injection, it dropped to 1.4 ng/ml drastically (p<0.05). Secondly, one hundred and ninety four Hanwoo heifers or cows were divided into two groups to compare estrous induction and conception rates: the one treated with MGA and $PGF_{2{\alpha}}$, (n=104) and the other with $PGF_{2{\alpha}}$ treatment (two injections at 11 days interval, n=90). The heifers or cows treated with MGA and $PGF_{2{\alpha}}$ were identical to those used as above. The percentages of heifers or cows showed estrus were higher in the $MGA+PGF_{2{\alpha}}$ treatment (91.3%) than in the $PGF_{2{\alpha}}$ treatment (72.2%, p<0.05). Conception rates were also higher in the $MGA+PGF_{2{\alpha}}$ treatment (94.2%) than in the $PGF_{2{\alpha}}$ treatment (88.9%, p<0.05). The results of this experiment indicate that estrus synchronization using $MGA+PGF_{2{\alpha}}$ is more effective than that using $PGF_{2{\alpha}}$ (two injections) in Hanwoo.

• Korean Journal of Animal Reproduction
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• v.7 no.2
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• pp.8-26
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• 1983

Various early pregnancy diagnostic methods have been developed in order to improve the reproductive efficiency in cow, mare, mule, sow, sheep, goat, dog, cat, rabbit, buffalo, camel, elephant, monkey, deer, lion, coipus and guinea pig. These methods include abdominal swelling, abdominal palpation, esturs cylce detection, Lupin test, gonadotropin assay, colostrum injection test, sperm motility assessment, cervical mucus viscosity test, Kaber chromagens method, estrogen test, A Scheim-Zond다 test, spectrophotometric detection of estrogen in urine and feces, boric acid crystraline formation test in urine, oxytocin injection test, diamino-oxidase test, PMSG HA test, behaviour test, Simolus iodine detection test, detection of tryptophane in urine, x-ray method, Cuboni and Lunaas method, vaginal biopsy method, Friedmann Schneider diagnostic method, electrode method, barium chloride detection method, ECG, Doptone method, ultrasound method, ultrasound scanning method, LDH method, rectal palpation method, CL palpation method, radioautography, serum creatine test, serum globulin test, chlormadine method, CAP method, Medata Do, pp.ers method, body fluid test, Plasma oCS detection method, ERIA, LHRH method, negative latex cogulation test and oestrone sulphate detection method. The most reliable methods with high a, pp.icability to farm animals such as sheep, mare, sow and cow are rectal palpation, ultrasound method and hormonal assay in blood and milk. However, they require complicated laboratory works for the early diagnosis of pregnancy and in most cases, the simple and economical methods which are described up to now need a long period of time after conception. Generally, it is possible to detect pregnancy after one estrus cycle, even though it varies depending on the species of animals. For improvement of the reproductive efficiency, it is required to develop a more accurate, economical, simple and early detectable method. It is anticipated that the result of a study on the detection method of EPF(early pregnancy factor) would be a, pp.icable to various animals within 6 hours after conception.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.233-243
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• 1984

The present study was carried out to determine the changes of the sex hormone levels in serum throughout the estrous cycle and the gestation period on the Landrace gilts. The blood samples were taken from the vein of six gilts. LH, FSH, prolactin, progesterone, $estradiol-17{\beta}$ and cortisol in serum were analyzed by the radioimmunoassay methods. The results obtained on this study were summarized as follows; 1. The age at puberal estrus was 179.5 days, the weight at puberal estrus was 88.2kg, the length of estrous cycle was 21.3days, the gestation length was 114days and the litter size was 9.5 head in the Landrace gilts. 2. During the estrous cycle, the serum LH and prolactin concentrations were below 1.56mIU/ml and 2.4ng/ml, respectively, under the limit of detection of the assay. The FSH concentrations ranged from 1.50 to 2.20mIU/ml for day 6~15 after the estrus and they were below 1.25mIU/ml from day 3 to day + 3, with day 0 being the first day of the estrus. 3. Progesterone concentrations were 1.90ng/ml at day 0 of the estrus and increased about 13.1ng/ml at day 3 of the estrus, and reached peak levels at day 9. $Estradiol-17{\beta}$ concentrations were below 27.2pg/ml throughout the luteal phase, and reached about 27.2pg/ml at day 0 and day 18. Cortisol concentrations reached peak levels at dey 0 and ranged from 24.65 to 28.57ng/ml throughout the luteal phase. 4. During the gestation period, the concentrations of LH, FSH and prolactin ranged of 3.10~4.37mIU/ml, 1.30~1.80mIU/ml and 2.60~6.70ng/ml, respectively. 5. Progesterone concentrations declined from 38.90~16.85ng/ml throughout the pregnancy to 1.90ng/ml at the time of parturition. $Estradiol-17{\beta}$ concentrations increased from 27.20pg/ml at 15 days after the pregnancy to 620.17pg/ml at the time of parturition. Cortisol concentrations reached peak levels at the time of parturition and ranged from 13.58 to 22.31ng/ml throughout the pregnancy.

• Journal of Veterinary Clinics
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• v.20 no.3
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• pp.369-375
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• 2003

The ultrasonography was performed in 77,924 subestrous dairy cows from 680 dairy farms at 57 districts. The cows were examined for confirmation of resumption of ovaries and uterus after 30 days postpartum, for early pregnancy diagnosis after 30 days post-insemination, confirmation of pregnancy at 8 month post-insemination, and for diagnosis of reproductive dysfunctions, respectively. The results of reproductive examination by ultrasonography in 77,924 dairy cows were ovarian disorders 35,452 (46.8%), uterine disorders 10,721 (13.8%), pregnancy and pregnant failure 24,044 (30.8%), adhesion of reproductive tracts 167 (0.2%), freematins 13 (0.01%) and others 6,527 (8.4%) cows, respectively. The 13,732 (49.6%) cows out of 27,694 cows were treated for silent heat or error of estrus detection, 3,473 (12.5%) cows for follicular cysts, 815 (3.0%) cows for luteal cysts, 606 (2.2%) cows for inactive ovaries, 4 (0.01%) cows for granulosa cell tumors, and 6,455 (23.3%) cows for endometritis, respectively. The indices of reproductive efficiencies before (2001-08-10) and after (2003-07-20) periodical examination of reproductive status were as follows; the mean intercalving interval were shortened from 471 days to 383 days, the mean interval calving to conception were shortened from 187 days to 99 days, the mean interval calving to first service were shortened from 105 days to 67 days, the mean cows showing heat by 60 days postpartum were increased from 33% to 89%, the mean conception rate to first service were increased from 43% to 68%, and the mean service per conception were shortened from 2.6 times to 1.8 times, respectively. These results suggest that periodical examination of reproductive status would be useful for the improvement of the reproductive performance in dairy cows.