• Journal of Embryo Transfer
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• v.18 no.2
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• pp.151-156
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• 2003

The objective of this study was to investigate response of corpus luteum, recovery rate of embryos and production of transferable embryos according to superovulation by PEG 30% FSH in Hanwoo. Cows were selected as recipient, subsequent were superovulated with a total of 400 mg NIH-FSH-P1(Folltropin-V, Canada) given by one shot subcutaneously. At the time of five days after Folltropin injection, 25mg of a PGF$_2$a was injected and cows were inseminated 12 and 24h after the onset of estrus. Seven days after insemination, embryos were collected non-surgically and were cryopreserved by direct transfer methods. The results are summarized as follows : 1. Response of corpus luteum following the superovulation in Hanwoo, right ovary were 52.8%(271/513) and left ovary were 47.1%(242/513), respectively (P<0.05). 2. Recovery rate of embryos following the number of corpus luteum were 83.0%(426/513). 3. Mean number of embryos recovered and transferable embryos were 7.74 and 6.43, respectively (P<0.05). 4. In the total number of transferable embryos per flush were collected 6.4 and all saved transferable embryos were 355.

• Korean Journal of Animal Reproduction
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• v.27 no.3
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• pp.269-274
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• 2003

The purpose of this study was to determine the effect of rbST treatment on progesterone concentration, volume of luteal tissue and pregnancy rate following embryo transfer. Recipient cows were assigned to control and rbST group, of which was given a single injection of rbST (500 mg. sc) at estrus detection. The concentration of progesterone was not significantly different between control and at 0, 3, 6 days after rbST treatment. However, the concentration of progesterone at 9, 12 days was significantly higher than in control group (4.6 and 6.8 vs. 3.9 and 4.5 ng/ml P4). The pregnancy rate after embryo transfer in rbST treatment was significantly higher than in control group (64.0 vs. 47.1 %; p<0.05). The results indicated that rbST treatment in recipient cows could be improved the efficiency of pregnancy rate after embryo transfer.

• Reproductive and Developmental Biology
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• v.36 no.1
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• pp.87-93
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• 2012

The purpose of this experiment is to compare the pregnancy rate (PR) according to the state of the ovaries and uterus, according to the number of embryos transferred from cows and heifers and to investigate the method of artificial twin induction with Hanwoo $in$ $vitro$ fertilized (IVF) embryos by embryo transfer (ET). Looking at the PR according to the condition of the ovaries and uterus, the result was not influenced by the condition of the ovaries, but was significantly influenced by the state of the uterus. The PR according to the number of embryos transferred from cows was 36.8%, 53.0%, 50.5% for 1, 2, and 3 embryos respectively, and although there was a higher frequency of twin calves with 3 embryos than with 2, the calving rate was the highest with 2 embryos. In case of heifers, the transfer of 1 embryo showed the best pregnancy and calving rate, and although the PR was similar with 2 embryos (67.7 versus 66.4), in case of 2 embryos transferred there was high frequency of embryonic loss( 6.1%) occurred when a cow was diagnosed at 28 and 53 d after ET, total loss (21.3%; sum of fetal death, abortion and stillbirth after pregnant diagnosis at 60 day).

• Reproductive and Developmental Biology
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• v.36 no.2
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• pp.95-101
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• 2012

The purpose of this experiment was to compare the pregnancy rate (PR) according to the state of the ovaries and uterus, according to the number of embryos transferred from cows and heifers and to investigate the method of artificial twin induction with Hanwoo in vitro fertilized (IVF) embryos by embryo transfer (ET). Looking at the PR according to the condition of the ovaries and uterus, the result was not influenced by the condition of the ovaries, but was significantly influenced by the state of the uterus. The PR according to the number of embryos transferred from cows was 36.8%, 53.0%, 50.5% for 1, 2, and 3 embryos, respectively and although there was a higher frequency of twin calves with 3 embryos than 2, the calving rate was the highest with 2 embryos. In case of heifers, the transfer of 1 embryo showed the best pregnancy and calving rate, and although the PR was similar with 2 embryos (67.7 versus 66.4), in case of 2 embryos transferred there was high frequency of embryonic loss (6.1%) occurred when a cow was diagnosed at 28 and 53 d after ET, total loss (21.3%); sum of fetal death, abortion and stillbirth after pregnant diagnosis at 60 day.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.187-193
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• 2003

Recently a protocol was developed that precisely synchronizes the time of ovulation in Hanwoo. Cows were treated with GnRH on Day 0, PGF$_2$$\alpha$ 7 d later, GnRH 2 d later, and then time-inseminated approximately 24 h after this second treatment with GnRH. Ovarian morphology was monitored cows by trans-rectal ultrasonography 6.5MHz linear transrectal probe(Sonovet - 600., Medison co. Korea) from 24 hr to 31 hrs after second GnRH injection. The result obtained summarized as follows - 1. Induced ovulation were 24 to 31hr after the second GnRH injection, but high induced ovulation was 28hr. 2. Conception rate with HML(High meat lin) and HIL(High milk lin) treatment were 48.1％(38/79) and 43.9％(40/91), respectively. 3. Conception rate of 1∼2 parity and 3∼4 parity was 44.3％ and 55％, respectively. 4. Conception rate of spring, autumn was more increased, 47.3％ than summer.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.2
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• pp.151-156
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• 2013

Hanwoo (Also known as Korean native cattle; Bos taurus coreanae) have been used for transportation and farming for a long time in South Korea. It has been about 30 yrs since Hanwoo improvement began in earnest as beef cattle for meat yield. The purpose of this study was to determine the trend of improvement as well as to estimate genetic parameters of the traits being used for seedstock selection based on the data collected from the past. Hanwoo proven bulls in South Korea are currently selected through performance and progeny tests. National Hanwoo genetic evaluations are implemented with yearling weight (YW), carcass weight (CW), eye muscle area (EMA), backfat thickness (BF) and marbling score (MS). Yearling weights and MS are used for selecting young bulls, and EMA, BF, and MS are used for selecting proven bulls. One individual per testing room was used for performance tests, and five individuals per room for progeny tests. Individuals tested were not allowed to graze pasture, but there was enough space for them to move around in the testing room. Feeds including roughages and minerals were fed ad libitum, and concentrates were provided at the rate of about 1.8% of individual weight. Overall means of the traits were $352.8{\pm}38.56$ kg, $335.09{\pm}44.61$ kg, $77.85{\pm}8.838\;cm^2$, $8.6{\pm}3.7$ mm and $3.293{\pm}1.648$ for YW, CW, EMA, BF and MS. Heritabilities estimated in this study were 0.30, 0.30, 0.42, 0.50 and 0.63 in YW, CW, EMA, BF and MS, respectively, which are similar to results from previous research. Yearling weight was 315.54 kg in 1998, and had increased to 355.06 kg in 2011, resulting in about 40 kg of improvement over 13 yrs. YW and CW have improved remarkably over the past 15 yrs. Breeding values between 1996 and 2000 decreased or did not change much, but have moved in a desirable direction since 2001. These improvements correspond with the substantial increase in use of animal models since the late 1990s in Korea. Hanwoo testing programs have practically contributed to the improvement in aspects of quality and quantity. In sum, the current selection system is good enough to accommodate circumstances where fewer sires are used on many more cows. Although progeny tests take longer and cost more, they seem to be appropriate under the circumstances of the domestic market with its higher requirement for better meat quality. Consequently, accumulative data collection, genetic evaluation model development, revision of selection indices, as well as cooperation among farms, associations, National Agricultural Cooperative Federation, universities, research institutes, and government agencies must be applied to the Hanwoo selection program. All these efforts will assist the domestic market to secure a competitive position against imported beef under Free Trade Agreement trade system and will provide farmers with higher profits as well as the public with a higher quality of beef.

• Korean Journal of Agricultural Science
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• v.43 no.4
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• pp.603-611
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• 2016

The aim of this study was to analyze the contribution factors (backfat thickness, eye muscle area, carcass weight, marbling score, and feeding period) affecting meat unit price (South-Korean Won / Kg of meat). The best slaughtering age to maximize unit price was also assumed. All data used in this study were acquired from the Korea Institute for Animal Products Quality Evaluation from 2010 to 2014. Contributions to the estimated unit price of cows by the following factors, backfat thickness, eye muscle area, carcass weights, feeding period, and marbling score were 2.65%, 0.04%, 1.58%, 1.58%, and 95.72%, respectively. Contribution to estimated unit price of steers by the same factors (backfat thickness, eye muscle area, carcass weights, feeding period, and marbling score) were 7.88%, 1.24%, 0.07%, 90.81%, and 95.72%, respectively. Slaughtering ages ranged from 26 to 36 months and the data were separated into each month for an 11 month period. The unit price of meat from Hanwoo slaughtered at 30 months was highest among groups. The lowest unit price was observed in the group belonging to the Hanwoo slaughtered at 36 months. In conclusion, of all contributing factors, marbling score affected unit price the most. Based on our results, it is recommended that the optimal slaughtering age be set at 30 months to maximize unit price. Moreover, the feeding of beef cattle past 30 months of age is not recommended because of the increase in feeding costs.

• Journal of Animal Science and Technology
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• v.63 no.5
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• pp.1064-1075
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• 2021

Recently, a high level of dietary crude protein (CP) has become of interest as a possible practice to improve the carcass quality of beef cattle, and its level has been increasing in the field. However, there is little scientific evidence that supports this. This study was conducted to test whether a high dietary CP level would improve growth performance, body metabolism, and carcass traits in Hanwoo beef cattle. A total of 32 Hanwoo finishing beef cattle (18 multiparous cows, six heifers, and eight steers) participated in a 12-weeks feeding trial. Two kinds of total mixed rations were prepared to contain two different CP; 156 g/kg for the control (CON) and 173 g/kg of CP for the treatment (HCP), while maintaining a similar level of metabolizable energy. The experiment was ended when more than half of the steers reached the target body weight (730 kg). Blood was collected at the end of the experiment. After harvesting, the carcass trait was evaluated at the slaughterhouse according to Korean standards. The carcass yield score and grade were also calculated based on revised criteria. Overall, dry matter intake, average daily gain, blood metabolites concentration, and the carcass traits, except for backfat thickness and the yield score, did not differ between the treatments. The HCP had lower backfat thickness than those of CON. There was no difference in the carcass yield grade, but the yield score was higher in the HCP treatment. According to the newly revised carcass grading criteria, both yield score and grade were higher in HCP than in CON. Increasing CP supply decreased the carcass's backfat thickness without altering growth performance and body metabolism, resulting in improved yield score and grade. Therefore, feeding a high CP diet may be beneficial in the farm income, although it may also increase feed cost and nitrogen excretion to the environment.

• Food Science of Animal Resources
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• v.39 no.4
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• pp.655-667
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• 2019

The present study aimed at investigating the effects of dry- and wet-aging methods on flavor compounds and sensory properties of low fat Hanwoo beef muscles. All the beef samples were obtained from 2-grade carcasses of Hanwoo cows. The beef samples used in the dry- and wet-aging methods were prepared in the forms of quarter beef (bone-in) and cuts (boneless), respectively. The dry-aging was carried out at $2^{\circ}C-4^{\circ}C$ and humidity of 65%-85%, while the wet-aging was done at $1^{\circ}C$ for 0, 20, 40, and 60 d. At each aging time, three muscles: longissmus thoracis (LT), glutaeusmedus (GM) and semimembranosus (SM) were taken from the corresponding quarters and cuts, and used for the flavor compounds and sensory analyses. Results showed that both aging methods significantly increased the concentrations of flavor compounds and total amount of all classes of the flavor compounds as the aging time increased (p<0.05). In the dry-aging method, the GM and SM muscles presented significantly higher total amounts of pyrazines and sulfur-containing compounds compared to the LT muscle (p<0.05). Both the aging methods improved the eating quality attributes, indicating by increased scores of sensorial attributes with increased aging time for all the muscles studied (p<0.05). However, compared to the wet-aging, the dry-aging method resulted in significantly higher scores of tenderness and flavor for the GM and SM muscles after 40 to 60 d. Thus, postmortem aging, especially the dry-aging method could be used to improve eating quality attributes (tenderness and flavor) of low fat beef muscles such as GM and SM.

• Korean Journal of Agricultural Science
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• v.46 no.2
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• pp.395-404
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• 2019

This paper investigated the changes in Hanwoo breeding farms and herds according to their farm size and farm types based on traceability data in the Hanwoo industry. The major results are summarized as follows. First, the notion that small sized farms are breeding farms and middle or large sized farms are fattening farms is wrong. The results show that middle or large farms are not only fattening cattle but also breeding female cattle. Based on cattle data for over 6 months and under the criteria of a female cow ratio of 10 and 90% using the 2/4 quarter of 2018, the results show that the ratio of fattening only farms is 5.7%, that of breeding only farms is 59.0%, and that of fattening and breeding farms is 36.1%. The ratios of fattening, breeding, and both are 13.3, 13.5, and 73.2%, respectively, for a farm size with over 100 cattle. Second, this study found that the ratio of breeding farms over total farms has been increasing continuously over the last 5 years. This trend is apparent in the middle or large sized farms. However, the birth rate of cows is relatively lower in the middle and large sized farms than in the small sized farms. Hence, we can infer that the demand for a detection system for standing estrus in female cattle will increase. Additionally, the government should prepare relevant policies to stabilize the managerial conditions of middle or large sized farms.