The present study was conducted to examine the effect of soybean silage as a crude protein supplement for corn silage in the diet of Hanwoo steers. The first experiment was conducted to evaluate the effect of replacing corn silage with soybean silage at different levels on rumen fermentation characteristics in vitro. Commercially-purchased corn silage was replaced with 0, 4, 8, or 12% of soybean silage. Half gram of the substrate was added to 50 mL of buffer and rumen fluid from Hanwoo cows, and then incubated at 39°C for 0, 3, 6, 12, 24, and 48 h. At 24 h, the pH of the control (corn silage only) was lower (p<0.05) than that of soybeansupplemented silages, and the pH numerically increased along with increasing proportions of soybean silage. Other rumen parameters, including gas production, ammonia nitrogen, and total volatile fatty acids, were variable. However, they tended to increase with increasing proportions of soybean silage. In the second experiment, 60 Hanwoo steers were allocated to one of three dietary treatments, namely, CON (concentrate with Italian ryegrass), CS (concentrate with corn silage), CS4% (concentrate with corn silage and 4% of soybean silage). Animals were offered experimental diets for 110 days during the growing period and then finished with typified beef diets that were commercially available to evaluate the effect of soybean silage on animal performance and meat quality. With the soybean silage, the weight gain and feed efficiency of the animal were more significant than those of the other treatments during the growing period (p<0.05). However, the dietary treatments had little effect on meat quality except for meat color. In conclusion, corn silage mixed with soybean silage even at a lower level provided a greater ruminal environment and animal performances, particularly with increased carcass weight and feed efficiency during growing period.

The objective of this study was to investigate the effects of dry-aging and wet-aging conditions on the chemical composition, meat quality traits (color, water holding capacity, cooking loss, WBSF and pH) and shelf-life TBARS (2-thiobarbituric acid reactive substances) and VBN (volatile basic nitrogen) of loin (M. longissimus thoracis), sirloin (M. glutaeusmedus) and top-round (M. semimembranosus) cuts of Hanwoo cows. The dry-aging condition (temperature ℃, relative humidity %) was done for 60 d as 2℃, 65％, 20 d＋2℃, 75％, 20 d＋4℃, 85％, 20 d while, the wet-aging was done for 60 d at 1℃, 85%. Results revealed that moisture content was significantly higher in the dry-aged samples than that of the wet-aged samples at 60 d (p<0.05). The a*- and b*-values were significantly higher in 3 cuts as compared with those treated with wet-aging condition. During the dry-aging time, the WHC significantly increased in the loin and sirloin and they were significantly higher than wet-aging condition at 40 d and 60 d (p<0.05). The WBSF values significantly decreased with increased aging time and there was no significant difference between two aging methods. The TBARS and VBN contents significantly increased with increased aging time for all the wet- and dry-aged cuts, and their levels still fell within the acceptable standard limit. Generally, the TBARS and VBN contents were significantly higher in the dry-aged cuts, probably due to the increased levels of protein and fatty acids oxidations. Based on the results obtained in the present study, it can be suggested that application of dry-aging method can improve the quality characteristics of beef.

These studies were conducted to evaluate developmental competence of follicular oocyte collected from the ovaries of Hanwoo cows with the high offspring meat quality (1++ and 1+ grade). Cumulus oocyte complexes from individual cows were matured, fertilized and cultured using protocols of in-vitro maturation (IVM), in-vitro fertilization (IVF) and in-vitro culture (IVC). The rates of blastocyst development from Hanwoo cows with the offspring meat quality grades of 1++ and 1+ were 18.6 and 21.2%, respectively. The rates of blastocyst development were 26.3, 20.7, 20.7, 17.2 and 31.2% from Hanwoo cows with the meat quality grades of 1++, 1+, 1, 2 and 3, respectively. Fiftyseven transferable embryos were recovered from 11 Hanwoo donor cows (5.2/head) with the high offspring meat quality grades of 1++ and 1+ in vivo, and the pregnancy rate after embryo transfer was 61.1%. In conclusion, these results suggest that in vitro embryo production from the ovaries of cows with the high meat quality grades using individual culture system can be used an efficient method for livestock improvement. In addition, for the successful industrialization of embryo transfer, conception rate should be improved.

These studies were conducted to establish the practical Hanwoo (Korean native cattle) improvement system through the combining of embryo transfer technology and confirming individual Hanwoo oocyte culture system and to investigate that correlation of Hanwoo carcass classification (intramuscular marbling) and oocyte donor for blastocyst production in vitro. In case of Hanwoo, the carcass meat quality grades were divided to grade 1⁺⁺, 1⁺, 1, 2, and 3 depends on fat distribution of longest muscle cross-sectional surface. As results, the numbers of follicular oocytes collected from individual fundamentally-registered Hanwoo yielded 1⁺⁺, 1⁺, 1, 2 and 3 meat quality were 9.5, 9.4, 8.5, 8.8 and 8.8 per ovary, respectively. The numbers of retrieval oocyte from follicles were significantly higher in the cattle yield 1⁺⁺, 1⁺ meat quality than in the cattle yield 1, 2 and 3 meat quality (p<0.05). The rates of blastocyst formation were 18.2, 21.3, 29.4, 30.9, and 31.5% in the cattle yield 1⁺⁺, 1⁺, 1, 2 and 3 meat quality of after in vitro maturation, respectively. It was significantly lower in the cattle yield 1⁺⁺ and 1⁺ meat quality than in the cattle yield 1, 2 and 3 meat quality (p<0.05). In order to evaluate embryos quality, TUNNEL assay was conducted for each meat quality grade using blastocyst stage embryo on day 8. The results showed that apoptosis cell number was higher tendency in the cattle yield 1⁺⁺and 1⁺ meat quality (81 and 79, respectively) than in the cattle yield 1, 2 and 3 meat quality (51, 48 and 50, respectively) but there was no statistical significance in each group. After embryo transfer, the conception rate of recipient was 53.5 (23 out of 43), 52.1 (38 out of 73) and 58.0% (58 out of 100) in the meat quality of 1, 1+ and 1++, respectively. These results showed that the conception rate was significantly higher in the cattle yield 1 meat quality than in the cattle yield 1⁺⁺, 1⁺ , 2, and 3 meat quality (p<0.05). In summary, these results indicate that the application of confirming Hanwoo individual oocyte culture system and embryo transfer technology can make good use of the genetic resources conservation and improvement of Hanwoo. Relevance of the meat quality grade and reproductive ability of carcasses of Hanwoo will be considered to be one of the effective means for the associated research with obesity and reproduction.

The objective of this study was to investigate meat quality and nutritional composition of 10 cuts (loin, striploin, chuck roll, chuck tender, short plate, brisket, bottom round, top sirloin, eye of round, and top round) from quality grade 1 beef from 11 Hanwoo steers at Hanwoo Experimental Station of National Institute of Animal Science. The protein contents were higher in top round (Udoon) and eye of round (Hongduke) and lower in loin (Dngsim) and short plate (Abjin) when compared to the other cuts (p<0.05). Whereas the intramuscular fat contents were highest in loin (12.51%), those were lowest in top round (4.14%) (p<0.05). The calories were higher in loin and short plate and lower in top round, chuck tender (Guri), top sirloin (Bosup), eye of round, chuck roll (Moksim), and bottom round (Sulgit) (p<0.05). The cooking loss (%) was 24.38% in loin and it was lower than the other cuts (p<0.05). The bottom round had higher water holding capacity (WHC) and chuck tender had lower WHC than those in the other cuts (p<0.05). In meat color, L* values were higher in loin and lower in top round than the other cuts (p<0.05). Total saturated fatty acid contents were higher in loin and lower in bottom round than the other cuts (p<0.05). In amino acid compositions, top round had significantly higher than those in the other cuts (p<0.05). The iron contents were higher in chuck tender and chuck roll contained higher iron contents than those of the other cuts (p<0.05). In conclusion, the meat quality and nutritional properties were significantly different among 10 cuts in the same quality grade of Hanwoo beef. Therefore, the provision of the meat quality and nutritional information of 10 cuts to consumers could be important for utilization and balanced consumption of different cuts.

Analysis of meat quality grade based on the DNA identity test samples were done on 320 Hanwoo (Korean cattle) raised in Gyeonggi region of Korea. 62.29% of cows and 91.35% of steers showed high quality which was above 1st beef grade. However, differences were observed between Gyeonggi Hanwoo and total slaughtered Hanwoo in Gyeonggi in the year 2009, though the sampling was entirely based high quality meat. Meat samples of pedigree registered cattle showed high rate of above 1st meat grade compared to advanced and fundamentally registered cattle. Pedigree registry is associated with quality grade of beef like the sex of cattle. Appearance rate of above 1st beef grade in offsprings of the top 9 Korean Proven Bulls produced through mating to Gyeonggi Hanwoo was 43.27% which was found to be higher than the average grade in cows (47.3%) and was 13.08% higher than the average grade in steers (77.49%). Our results showed superior genetic characters of Korean Proven Bulls which favors and influence the meat quality grade of their offsprings. Furthermore, our results claim that sex of Hanwoo irrespective of pedigreed or Korean Proven Bulls affects and/or influence the meat quality. Conclusively, the results could therefore be used as a basic data for the improvement of beef quality. However, paternity test by DNA typing and huge sample needs to be analysed to authenticate the findings.

본 연구는 축산물품질평가원에서 제공한 2007년 7월 1일부터 2009년 4월 30일까지의 도체등급판 정자료 20,450,773두의 등지방두께, 도체중 및 육질등급 자료를 이용하였으며, 등지방두께와 도체중 에 대한 환경효과를 추정하였고, 성별, 등지방두께별, 도체중별 등급출현율을 추정하였다. 조사된 형 질의 평균치는 도체중과 등지방두께가 각각 85.97±0.002 kg, 20.76±0.001 ㎜로 나타났다. 성의 효과 에서는 거세돼지의 도체중과 등지방두께가 각각 86.25±0.003 kg과 22.55±0.002 ㎜로 나타나, 다른 암 퇘지나 수퇘지에 비하여 유의적으로 높게 나타났고, 도축 년도의 효과에서는 년도가 경과함에 따라 도체중과 등지방두께가 증가하는 경향을 나타내었으며, 도축 계절의 효과에서는 도체중의 경우 겨 울에 87.00± 0.007 kg으로 유의적으로 무겁게 나타났고, 등지방두께의 경우 가을에 19.32±0.004 ㎜로 유의적으로 두껍게 나타났다. 성에 대한 육질등급 출현율의 경우 온도체와 냉도체 모두 거세돼지의 상위등급 출현율이 암퇘지에 비하여 높게 나타났다. 도체중에 대한 육질등급 출현율의 경우, 온도체 와 냉도체 모두 84∼88 kg 그룹에서 상위등급 출현율이 다른 그룹에 비하여 높게 나타났다. 등지방 두께에 대한 육질등급 출현율의 경우 온도체와 냉도체 모두 22∼24 ㎜ 그룹에서 상위등급 출현율이 다른 그룹에 비하여 높게 나타났다.

In this study, the analysis of meat quality grade was carried out on the DNA identity test samples of 452 Hanwoo (Korean cattle) raised in Gyeongnam region in the year 2009. Appearance rate of above 1st grade from cow (70%) and steer (93.16%) showed high quality grade. On the other hand, there were the difference between this study and slaughtered Hanwoo in Gyeongnam in the year 2009 - appearance rate of above 1st grade from cow (58.77%) and steer (82.99%). It expect considered influence of the samples for beef DNA identity test that collected mainly high quality meat. Quality grade by registry classification about collected samples showed correlation between pedigree classification and quality grade that appearance rate of above 1st grade highly observed pedigree registry more than advanced registry, advanced registry than fundamental registry. Although limited to DNA identity test samples, KPN (Korean Proven Bull's Number) 452 and KPN 407 was preferred for breeding in Gyeongnam. Also average appearance rate of above 1st grade in offsprings of the top 10 Korean Proven Bulls used mating is 95.35%. It means that Korean Proven Bulls influence meat quality of offsprings positively. Thus, this analysis is expected to be a base data for the improvement of meat quality of Hanwoo raised in Gyeongnam region.

도축 소의 난소를 이용하여 체외에서 수정란 생산과 이식이 산업화에 접어들고 있지만, 그 기원이 되는 난소의 자질은 검토되어 있지 않고, 생산된 송아지의 자질 또한 의문시 되고 있는 실정이다. 본 실험에서는 도축 한우의 육질과 육량에 따른 배발달율을 조사하여 고품질 체외수정란의 생산에 기초를 확립 하고자 실시하였다. 한우 난소는 도축 직후에 개체별로 paper에 싸서, 0.9%생리식염수 (25-)가 들어있는 보온병에 담아 실험실로 운반하였다. 운반된 난소