• Korean Journal of Animal Reproduction
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• v.27 no.2
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• pp.135-142
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• 2003

The objective of this study were to investigate the effects of Se and Vit. E administration at last month or two month before parturition on the reproductive function of dams and developmental ability of calves. On developmental ability of calves obtained afier Se and Vit. E administration at the last month of pregnancing periods, the birth weight were significantly higher in administration groups than in control group(P<0.05). However, the weaning weight, average daily gain and weaning age were not significantly difference in all experimental groups. In the comparision of reproductive function in dams, estrus postpartum was faster in treatment groups than control groups(P>0.05). However, the number of A.1 service fur conception were lower groups injected than control group(P>0.05), there were not significantly differences in all experimental groups. The developmental ability of calves obtained after Se and Vit. E administration at two months before parturition were also examined. The birth weight, weaning weight, average daily gain and weaning age were higher in treatment groups than control group, but there were not significantly differences in all experimental groups. In reproductive function of dams, the days to 1 st estrus postpartum was slightly faster injected groups than control group(P>0.05). Number of A.I. service for conception in each groups were lower in treatment groups than control group.

• Journal of Animal Science and Technology
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• v.54 no.2
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• pp.141-147
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• 2012

The present survey was conducted to provide basic information on Hanwoo calf management. Eight hundred and sixty-two Hanwoo breeding farms from all nine provinces were surveyed via personal interviews. The percentages of farms categorized by herd size were 30.5%, 32.8%, 26.0% and 10.7% for <50 heads, 51-100 heads, 101-200 heads, and >200 heads, respectively. More than 50% of farms offered calf starter at 6-10 days of age, showing that calf starter was offered relatively at an earlier age. Calf starter was replaced every three days by 30.1% of farms. The percentages of farms replacing starter weekly (19.2%) were even higher than those of replacing starter daily (18.8%), suggesting that the frequency of replacing starter needs to be increased to maintain starter freshness and to increase starter intake. About one-third of farms offered forage at 6-10 days of age and 21% of farms offered even at 1-5 days of age although it has been well known that forage does not contain either nutrient density or nutrient profile necessary to stimulate rumen papillae development, especially before weaning. Furthermore, about half of farms used rice straw with calf starter. Water was offered relatively at an earlier age (1-5 days of age) by 55% of farms. Deciding when to wean calves should be based on starter intake rather than age but less than 50% of farms decided weaning age by starter intake. In conclusions, to reduce weaning age of Hanwoo calves by rapid rumen papillae development it is necessary to provide fresh starter and water by increasing frequency of starter replacing and water trough cleaning and not to feed forage before weaning.

• Korean Journal of Animal Reproduction
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• v.22 no.4
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• pp.349-357
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• 1998

This study was to investigate whether the viability of Hanwoo IVM/IVF/IVC blastocysts was maintained after vitrification and thawing. In vitro produced Hanwoo blastocysts were vitrified by two-step method: equilibrated in EG20 for 3 min, and then exposed in EFS40 ［40% ethylene glycol (EG), 18% ficoll and 10.26% sucrose in mDPBS containing 10% FBS ］and vitrified in L$N_2$for 30 - 45 sec. After thawing, in vitro survival was assessed as the re-expanded and hatched rates at 24 hand 48 h, respectively. The results obtained in these experiments were summarized as follows: From the 12 replicates, 52.5% of Hanwoo blastocysts were produced in vitro at day 7 after IVF. When the effects of freezing solution to the embryo survival were examined, there is no significant toxicity in exposure (100.0, 73.8%) compared to that af control group (100.0, 87.0%). However, when embryos were vitrified, high survival (86.2, 55.4%) was obtained although it was significantly lower than those of exposure and control group (p＜0.05). When the in vitro survival of vitrified embryos according to developmental stage and culture day were examined, it showed that more advanced embryo stage exhibited a significantly higher survival rate irrespective of culture day (p＜0.05). Also, even in the same development stage, the in vitro survival of day 7 embryos (re-expanded: 75.0~87.5%, hatched: 21.4~66.7%) was higher than those of day 8 embryos(re-expanded: 58.6~78.3%, hatched: 10.3~52.2%). Therefore, these results suggested that in vitro produced Hanwoo blastocysts can be successfully cryopreserved by simple two-step vitrification method using EFS40 freezing solution, particularly at the expanded and early hatching blastocyst stage regardless of embryo culture duration (day 7 or day 8 after IVF).

• Journal of Animal Environmental Science
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• v.17 no.sup
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• pp.7-20
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• 2011

This study was conducted to analyze the mixing ratio of raw feed materials for the methane mitigation and also to identify the minimum rearing density for improving the productivity of beef calves as eco-friendly fodder. Raw materials used in this study for the formulation of feed for methane reduction were crushed corn and alfalfa along with other 21 species. In addition, to investigate the appropriate rearing density, 12 Hanwoo calves with average weight of 150 kg was selected and experiment was conducted for four months. Methane gas emission (Bo) is about 3-4 times less in TMR 4 compared to TMR 1, 2 and 3. Feed price calculated for TMR 4 ration was also affordable. In addition, all TMRs showed a normal ruminal pH. Disappearance rate was observed to be lower in TMR 4 as compared to TMR 1, 2 and 3, but methane production decreased by 24 to 37%. The result showed improved total body weight, average daily gain and feed conversion ratio in rearing low-density ($18m^2/head$), and general treatment ($9m^2/head$) compared to overcrowding treatment ($6m^2/head$). In addition, blood components (total protein, glucose, AST, ALT and GGT factors) involved in health and disease treatments and health-related nutrition metabolism are lower in the low-density and general treatment compared to the high density treatment. Postural development (development of body size) i.e., weight, height and width significantly increased in the low and general density treatment compared to high density treatment. Especially excellent improvement was observed in low-density treatment than the general treatment. Moisture content, colonic bacteria and coccidium are higher in low and high density treatments than in the general treatment. The adequacy for beef rearing density is considered to be more desirable in an area more than $6m^2/head$. In conclusion, present study suggests that possibility of methane reduction through adjusting mixed feed ration. Also, rearing density is also an important factor in the growth and development of beef calves.

• Journal of Embryo Transfer
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• v.20 no.2
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• pp.163-168
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• 2005

The objective of this study was to produce superior cows by sexual distinction of embryos collected from the donor with pedigree information. Collected embryos distinguished by biopsy using punching or bisection methods and Loop-mediated isothermal amplification of sex-determined DNA for sexing. Six embryos predicted as female were transplanted to recipients and then 2 pregnant cows were normally delivered of calves at 278 and 285 days after embryo transfer. Birth weights of calves named Barani and Borani were 18kg and 25kg, respectively. Adjusted body weights for 90 days were 61.1kg and 88.8kg, respectively. Average daily gains were 0.48kg and 0.71kg, respectively.

• Korean Journal of Animal Reproduction
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• v.23 no.4
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• pp.281-291
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• 1999

The objective of this study was to optimize the freezing/thawing method of in vitro produced Hanwoo blastocysts. Day 7 blastocysts after IVF were vitrified using EFS40 (40% ethylene glycol, 18% ficoll, 0.3 M sucrose and 10% FBS added m-DPBS) as a freezing solution and electron microscope (EM) grid (V-G) or straw (V-S) as an embryo container. In both method, freezing/thawing were treated by 2-step, treatment time was required in V-G method and V-S method, for 2 min / 3 min and 3.5 min / 10 min, respectively. Embryo survival was assessed as re-expanded and hatched rates at 24 h and 48 h after warming, respectively. The results obtained in these experiments were summarized as follows: when the effect of exposure in vitrification solution and chilling injury from freezing procedure on in vitro produced expanded blastocysts were examined, at 24 h after warming, embryo survival in exposure group (100.0%) was not different compared to that in control group (100.0%), although those results were significantly different with two vitrified groups (V-G: 87.8, V-S: 77.8%) (P＜0.001). However, at 48 h after warming, hatched rates of V-G group (67.8%) were significantly higher than those of V-S group (53.3%) (P＜0.05). In addition, this hatched rate in V-G group was not different with that in exposure group (73.3%). When the effects of embryo developmental stage (early, expanded and early hatching blastocysts) and embryo container (EM grid and straw) to the in vitro survival of vitrified-warmed day 7 Hanwoo blastocysts were simultaneously examined, fast developed embryos were indicated the better resistance to freezing than delayed developed one, irrespective of embryo containers (early; 57.1 ＆ 24.4%, expanded; 84.7 ＆ 60.6%, early hatching; 91.7 ＆ 80.0%) (P＜0.001). Especially, in expanded and early hatching blastocysts, embryo survival of V-G group (67.8, 95.0%) was significantly higher than those of V-S group (53.0, 65.0%) at 48 h post warming, respectively (P＜0.05, P＜0.001). Therefore, this study indicates that Hanwoo blastocysts can be cryopreserved more simple, efficient and successful by vitrification method using EM grid.

• Journal of Animal Science and Technology
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• v.46 no.2
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• pp.165-172
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• 2004

This study was conducted to investigate changes in physico-chemical characteristics of Hanwoo carcass according to different castration and slaughtering ages. Total 75 Hanwoo calves(average 4 months old) were randomly assigned to Control(bulIs). Treatment I. Il , III. or IV(castrated on 4. 9. 12. and 16 months of age, respectively) and slaughtered at 7. 9. 12, 16, and 28 months of age. Moisture contents in M. Longissimus dorsi of both Hanwoo bulls and steers were decreased as the slaughtering age increased. Moisture contents in all steer groups were significantly(P <0.05) lower(average 68.63%) than that in bulls(72.18%) at 28 months of age. Crude fat contents tended to increase as the slaughtering age increased. Crude fat contents in Treatment III(castrated at 12 months of age) at 28 months of age were 10.24% which was the highest among all steer groups. Crude protein contents in M. Longissimus dorsi of Hanwoo bulls were around 23% regardless of slaughtering age. Water holding capacity(WHC) of both bulls and steers tended to increase as the animals aged. Steers showed rapid increase in WHC after 16 months of age and showed higher(78.39%)) WHC than bulls(70.00%) at 28 months of age. Palmitic acid(CI8: 0) contents in Hanwoo bulls were increased as the slaughtering age increased(20.92 \longrightarrow 24.22%) whereas stearic acid(CI8: 0) contents were decreased(I8.l5 \longrightarrow11.32%). Oleic acid(CI8: I). a major unsaturated fatty acid. significantly(P <0.05) increased(25.59 \longrightarrow 37.90%) when slaughtering age of Hanwoo increased. Changes in fatty acid composition in Hanwoo steers were similar to those in bulls except oleic acid contents were higher and stearic acid contents were lower than bulls at 28 months of age.

• Korean Journal of Veterinary Service
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• v.41 no.1
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• pp.9-13
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• 2018

The best way to prevent foot-and-mouth disease (FMD) constantly occurring in Korea will be vaccination. In this study, FMD vaccines were given to Korean native cattle (Hanwoo), dairy cattle, and pigs to investigate the antibody positive rate of FMD vaccine by age in year and month. Hanwoo, dairy cattle, and pigs showed antibody positive rates of 99.5%, 97.7%, and 95.9%, respectively. High antibody positive rates more than 95% were found in Hanwoo and dairy cattle. In particular, high antibody positive rates were found in Hanwoo and dairy cattle regardless of age. Pigs showed a relatively low antibody positive rate of 57.6% at 3 months of age and then constantly maintained a high antibody positive rate of above 95.0% after 4 months of age. As a result of this study, high antibody positive rates were found when regular FMD vaccination was given to newborn calves and piglets after FMD vaccination twice to them. Therefore, it is considered the most important to receive vaccination thoroughly according to vaccination plan in order to prevent FMD.

• Journal of Embryo Transfer
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• v.29 no.3
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• pp.283-287
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• 2014

Sexed semen is commonly used for the production of calves of the desired gender. Gender selection is important in animal production industries. For example, female cattle are required for the dairy industry while males are preferred in the beef cattle industry. The present study was to assess the in vivo embryo production efficiency using the semen separated according to sex during superovulation in Hanwoo. Seventy Hanwoo donor cows were flushed on day 7 of estrus cycle with same FSH and artificial insemination by the same technicians. Embryos were recovered on 7 days after the third insemination by flushing the uterus with embryo collection medium. KPN semen straws used artificial insemination contained 20 million sperm (total number 60 million per donor). Sex-sorted semen straws contained 4 million sperm (total number 12 million per donor). The results obtained were as follows: No differences were observed in the efficiency of superovulation rates on KPN semen 87%, and sexed semen 100%, respectively. The mean numbers of total embryos are each $12.58{\pm}8.31$ and $13.25{\pm}7.86$. The mean numbers of transferable embryos, sexed semen were significantly lower than KPN semen ($3.75{\pm}1.98$ vs. $8.23{\pm}6.07$, P<0.05). The rates of unfertilized embryos from superovulation using sexed semen were significantly higher than KPN semen (50% vs. 15%, P<0.05). The rate of degenerated 2-cell embryos from sexed and KPN semen was 60.87% and 11.11%, respectively (p<0.05). In conclusion, these results indicate that superovulation using sexed semen was useful, but efficient embryo production was important to reducing the damage caused by the Flowcytometer-based sperm sorting procedure.

• Journal of agriculture & life science
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• v.45 no.6
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• pp.109-114
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• 2011

The objective of this study was to investigate the effects of environments (farms born, testing groups, age at the tests, date at slaughter, ages at slaughter) on body weights at 6, 12, 18 and 24 months of ages, body type measurements at 18 months of age and carcass characteristics in Hanwoo steer populations that were collected from commercial farms and reared in a progeny testing station. Performances of a total of 1,838 steer calves set for tests from 2004 to 2008 were recorded. Carcass characteristics were the carcass grading results evaluated and data collected slaughter scores at 24 months of age. For growth traits of all age classes and body type traits measured at 18 months of age, farms born, test group and linear covariate of age at test were fit in the models. For carcass traits, date at slaughter and linear covariate of ages at slaughter were fit in the models. Effect of farm at birth was not significant for body weight at 24 months of age. Carcass weight, eye muscle area, yield score and back fat thickness were affected by dates at slaughter but not by the ages at slaughter. Marbling score, however, was affected by these two effects. Farms at birth did not seem to affect body type measures greatly. This study will be utilized for Hanwoo Steers genetic evaluation.