• Asian-Australasian Journal of Animal Sciences
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• v.27 no.10
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• pp.1406-1410
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• 2014

Age at first calving is an important trait for achieving earlier reproductive performance. To detect quantitative trait loci (QTL) for reproductive traits, a genome wide association study was conducted on the 96 Hanwoo cows that were born between 2008 and 2010 from 13 sires in a local farm (Juk-Am Hanwoo farm, Suncheon, Korea) and genotyped with the Illumina 50K bovine single nucleotide polymorphism (SNP) chips. Phenotypes were regressed on additive and dominance effects for each SNP using a simple linear regression model after the effects of birth-year-month and polygenes were considered. A forward regression procedure was applied to determine the best set of SNPs for age at first calving. A total of 15 QTL were detected at the comparison-wise 0.001 level. Two QTL with strong statistical evidence were found at 128.9 Mb and 111.1 Mb on bovine chromosomes (BTA) 2 and 7, respectively, each of which accounted for 22% of the phenotypic variance. Also, five significant SNPs were detected on BTAs 10, 16, 20, 26, and 29. Multiple QTL were found on BTAs 1, 2, 7, and 14. The significant QTLs may be applied via marker assisted selection to increase rate of genetic gain for the trait, after validation tests in other Hanwoo cow populations.

• Journal of Animal Science and Technology
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• v.65 no.4
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• pp.748-758
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• 2023

This study was conducted to investigate the change in activity and mounting behavior in Hanwoo (Korean Native Cattle) during the peri-estrus period and its application to estrus detection. A total of 20 Hanwoo cows were fitted with a neck-collar accelerometer device, which measured the location and acceleration of cow movements and recorded the number of instances of mounting behavior by the altitude data. The data were analyzed in three periods (24-, 6-, and 2-h periods). Blood samples were collected for 5 days after the prostaglandin F2α (PGF2α) injection, and the concentrations of estradiol, progesterone, follicle-stimulating hormone, and luteinizing hormone were determined by enzyme-linked immunosorbent assays. Activity and mounting behavior recorded over 2-h periods significantly increased as estrus approached and were more efficient at detecting estrus than over 24- and 6-h periods (p < 0.05). Endocrine patterns did not differ with the variation of individual cows during the peri-estrus period (p > 0.05). Activity was selected as the best predictor through stepwise discriminant analysis. However, activity alone is not enough to detect estrus. We suggest that a combination of activity and mounting behavior may improve estrus detection efficiency in Hanwoo. Further research is necessary to validate the findings on a larger sample size.

• 축산식품과학과 산업
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• v.7 no.2
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• pp.56-67
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• 2018

• Food Science of Animal Resources
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• v.20 no.2
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• pp.87-92
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• 2000

This study was performed to provide scientific information for consumers and to increase the quality and consumption of Sullungtang prepared with bone from Hanwoo. The physico-chemical, sensory, nutritional properties of Sullungtang by different parity were investigated. The extracting extents of blood were significantly higher for heifer among Hanwoo cows with different parity(none, the second or the fourth) and for back bones among different bone portions (round, hind shank, arm, fore shank or back bone) (p〈0.05). For Sullungtang extracted from bones of heifer was higher in collagen contents than those extracted from cows with the second or the fourth parity. Sullungtang extracted from bones of heifer and cows with the second parity had significantly higher contents of condroitin and viscosity than those of cows with the fourth parity, however there was no significant difference between heifer and cows with the second parity. In color, L values were significantly high, and a and b values were significantly low for Sullungtang extracted from bones of heifer when compared to those extracted from the other cows with the second parity. The contents of total nitrogen, sodium, or calcium were higher for Sullungtang extracted from heifer than those from the cows with the second or the fourth parity. In amino acid compositions, the percentages of glycine were highest and proline and glutamic acid were followed fro all Sullungtang samples from Hanwoo. The results showed that the overall quality of Sullungtang significantly decreased as the parity increased for Hanwoo cows. The Sullungtang extracted from bones of heifer had the best sensory scores as well as nutritional quality when compared to those extracted from the cows with parity. Therefore, the labeling and price for cow bones should be differently evaluated by their parity and age in marketing system.

• Journal of Practical Agriculture & Fisheries Research
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• v.13 no.1
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• pp.103-114
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• 2011

The present survey was conducted to investigate effects of weaning age on market weights of steers and calf mortality in Hanwoo. Eight hundred and sixty-two Hanwoo cow-calf operations from all nine provinces were surveyed via personal interviews. The number of farms categorized by herd (heifer plus cow) size were 188, 364, 227 and 83 for <20 heads, 20~49 heads, 50~99 heads and >100 heads, respectively. Approximate 40% of farms surveyed weaned calves at three months of age. The percentages of farms weaning calves over three months of age were 53.5%, 37.5%, 43.7% and 39.0% for <20 heads, 20~49 heads, 50~99 heads and >100 heads, respectively. The herd size did not affect market weights of Hanwoo steers. However weaning age was negatively correlated to carcass weight of Hanwoo steers, showing that as weaning age decreased, carcass weights of Hanwoo steers increased. The average calf mortality was 5.6% and the herd size did not affect calf mortality. But weaning age was shown to be positively correlated to calf mortality and the rate of diarrhea that caused calf death, suggesting that as weaning age decreased, calf mortality and the rate of diarrhea decreased. Overall, the results of present study suggest that a decrease of calf weaning age in Hanwoo can increase the profit of Hanwoo cow-calf operations by increasing carcass weight of Hanwoo steers and by decreasing calf mortality.

• Journal of Animal Science and Technology
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• v.65 no.4
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• pp.865-877
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• 2023

Thirty Hanwoo cattle including bulls, cows, and steers (n = 10 each) were slaughtered and investigated for carcass traits (weight, meat color, fat color, yield index, maturity, marbling score, back-fat thickness, and firmness) and meat quality. The meat quality such as: pH, color, cooking loss, fatty acid, thiobarbituric acid reactive substance, warner-bratzler shear force, tensile tests, and texture profiles were analyzed on longissimus lumborum (LL) muscles of the carcasses at different aging times (3 d and 21 d). The results showed that steers and cows had higher back-fat thickness and marbling score, and a lower firmness (p < 0.001) than bulls. Bulls exhibited a lower meat quality indicating by higher cooking loss, thiobarbituric acid reactive substance content, warner-bratzler shear force and tensile test values (p < 0.01). Regarding the sensory property, the bull meat also had higher hardness, and lower tenderness, juiciness and flavor scores than the cow or steer meat (p < 0.01). Additionally, the bull meat had a higher polyunsaturated fatty acid and a lower monounsaturated fatty acid contents (p < 0.01). With increased aging time, the meat tenderness was improved in all the genders. Taken together, the present study demonstrated that the gender and aging time affected the carcass traits, fatty acid and sensory quality of beef. Postmortem aging could improve the meat tenderness of all genders especially bulls.

• Journal of Embryo Transfer
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• v.24 no.3
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• pp.207-212
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• 2009

The aim of present experiment was to examine commercial synthetic extender(AndroMed) for semen cryopreservation of Korean Black Bull. Semen was collected from a Korean Black Bull using an artificial vagina and transported to the laboratory. The semen was diluted 1:1 by AndroMed. The pellect was diluted to final sperm concentration of $5{\times}10^5/ml$ by doubling in every 10 minutes at $4^{\circ}C$ cold chamber. The semen was equilibrated for 1 hr at cold chamber and packed to 0.5 ml straw. The semen straws were located above 5 cm of liquid nitrogen for 5 minutes, above 5 cm for 10 minutes and above 10 cm for 10 min. And then the frozen straw was plunged to $LN_2$. The presented straws were examined the viability and motility after thawed at $37^{\circ}C$ water bath. Hanwoo semen was used as KPN (Korea Proven Bull Number) in this experiment. The survival rates was significantly higher in fresh semen than frozen semen ($80{\pm}14%\;and\;43{\pm}11%$). However, the motility rates was similar (80.7% and 66.4%). The survival and motility rates were higher in 5cm, 10 min treatment group than the other two groups in straw-located height and duration above $LN_2$ ($50{\pm}14%$ and 70.7% vs, 33.18% and $65{\pm}7%$ vs, 30.14% and 65.7%, respectively). The development rates to cleavage was higher in Black Cow than Hanwoo semen (62.2%, 64.4%), However, The development rates to blastocyst was higher in Hanwoo than Black cow semen (25.9%, 23.0%). In conclusion. The present results that acceptable fertilization and cryopreservation could be obtained by in vitro fertilization with frozen-thawed semen using a synthetic semen extender (AndroMed).

• Journal of Embryo Transfer
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• v.29 no.4
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• pp.327-331
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• 2014

The objective of this study was to investigate the interrelationship of weight and hormonal changes through the administration of vitamin A to first time pregnant heifers. A total of 28 Korean heifers was used for this study. The heifers were divided into two groups - with vitamin A (n=14) and without vitamin A (control) (n=14) in the feed. Body weight increased in vitamin A treated heifers starting 9 months until 15 months. After pregnancy, vitamin A treated heifers were found to maintain higher body weights than the control group. Pre-pregnancy and post pregnancy progesterone levels were not different between the two groups. Serum estradiol levels of heifers at different growth stages showed relatively higher E2 levels than the control. Also, the control during pregnancy may show higher serum E2 levels than the vitamin A treated heifers. The growth phase serum estradiol levels in heifers may be relatively higher than the control. During pregnancy it showed a similar trend. Serum levels of vitamin A treated heifers did not differ from pregnant heifers at 5 months of age. However, after 5 months from conception until 8 months of treatment it showed a high level. Serum cholesterol in pregnant cows was higher in the control group than the treatment from beginning until the end of pregnancy. This is considered to be related to fetus development during pregnancy, as well as the mother's health.

• Proceedings of the Korean Society of Crop Science Conference
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• 1998.10a
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• pp.68-111
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• 1998

The structure of the Hanwoo (Korean Native Cattle) Industry remains very weak and vulnerable to the WTO/IMF system. Considering that the majority of cattle farmers are small sized, and that marketing systems are outdated and inefficient, rapid expansion of lower priced beef imports by WTO system and rapid increasing of production costs by IMF system would lead to the deprivation of a regular source of farm income and threaten the stability of rural life. Accordingly, the Hanwoo industry should be expanded in accordance with progress in the implementation of (1) programs for the structural adjustment and (2) measures to compensate for the loss. Efforts for lowering major production factor costs needs to continue, In order to increase the supply of calves at low cost, the programs of collective cow-calf farms should be expanded, thereby reducing the cost of calf purchase, which constitutes the largest share of Hanwoo production cost. Also, feedlot operations should be encouraged for small herd farms in order to achieve a substantial saving in beef production costs by integrated operations from calf production to cattle fattening. A substantial saving would also be made by collective purchase and distribution of various inputs through the cooperatives' channels. Extension services should be strengthened for cattle farm management, cattle care and feeding, prevention of cattle disease, etc. In order to minimize cash outlays for commercial mixed feeds, utilization of far by-products as feeds should be enhanced and production of forage crops productive of resources, such as land and rural labor, during the farm o(f-season, needs to be encouraged. Also, technological development for enhancing the nutritional value of farm by-products should be encouraged. Measures for successful segregation of the Hanwoo beef market should be implemented, thereby enhancing incentive for quality beef producers and protecting consumers willing to pay higher price for quality beef. For development of the Hanwoo industry, a considerable time frame would be required in order for (1) small livestock farmers to make a successful adjustment by staying in the enterprise and achieving increased price efficiency (2) livestock farmers to acquire know-how for producing quality Hanwoo beef, (3) the ongoing Government policy of enhancing price-quality competitiveness, and for improving the quality Hanwoo beef marketing to take root. (4) consumers to increase their ability to distinguish meat quality, and others.

• Food Science of Animal Resources
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• v.30 no.2
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• pp.321-327
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• 2010

The effect of cattle sex (cow, bull, and steer) on carcass traits of quality grade factors, physicochemical, and sensory traits of Longissimus Dorsi in Hanwoo was evaluated. Carcass traits of 42,113 heads were collected nation-wide and 257 heads were slaughtered to analyze beef quality. Sex affected significantly marbling score, meat color, fat color, texture, maturity, and quality grade of Hanwoo (p<0.05). Hanwoo steer carcasses had the highest marbling score (5.02), maturity (2.17), and texture (1.31) than those of cows and heifers. Crude fat of steers was higher than that of other cows and bulls. Steers showed the highest $L^*$(39.01), Warner-Bratzler shear force (4.03 kg), and water holding capacity (57.08%), however, there was no significant differences between those of cows and bulls. Ultimate$pH_{24}$ was shown difference among sex (5.58-5.69), however, the values remained within normal range. In sensory evaluation analyses, sex affected significantly tenderness, juiciness, and flavor (p<0.05). Also, the over all acceptability of steer beef was significantly higher than that of cow and bull beef. These results could be used as fundamental data set for further research activities to elevate Hanwoo beef qualities (p<0.05).