Background: This study focused on reproductive traits in Hanwoo cattle, specifically the environmental factors affecting gestation length and birth weight. Methods: The records of 1,540 cows calved at the Hanwoo Research Institute from 2015 to 2023 were examined. This study analyzed two populations, linebreeding Hanwoo (LBH) and general Hanwoo (GH), with all cows undergoing estrus synchronization and artificial insemination. The R software was used to compare the differences between the two populations and analyze the environmental factors affecting each trait. Results: The results showed that the average gestation length for LBH was 283.28 ± 5.93 days, which was significantly shorter than that of the GH, which had an average of 285.63 ± 6.21 days (p < 0.001). The average birth weight of LBH calves was 25.10 ± 3.69 kg, significantly lighter than GH calves, which weighed 27.26 ± 4.11 kg on average (p < 0.001). Analysis of environmental factors revealed significant differences in the gestation length of LBH based on dam parity, year, and season of calving. However, no significant differences were observed based on calf sex. For LBH, birth weight showed significant differences based on dam parity, year of calving, and sex of the calf, but not the season of calving. In GH, gestation length varied with dam parity and calving season, but not with calving year or calf sex. The GH birth weight showed differences based on dam parity, year of calving, and calf sex, but not the season of calving. Conclusions: Reproductive traits in the Hanwoo cattle industry are economically vital but are heavily influenced by environmental factors due to their low heritability. An accurate evaluation of the genetic potential of these traits requires an analysis of the environmental factors affecting them. The results of this study serve as foundational data for predicting the potential for genetic improvement in the gestation length and birth weight of Hanwoo cattle.

The study aimed to investigate the impact of varying levels of neutral detergent-soluble fiber (NDSF) in Hanwoo growing cattle diets on rumen fermentation and methane (CH4) emissions. An in vitro rumen fermentation experiment utilized feeds with different NDSF levels, incorporating ingredients such as corn grain, soybean meal, soybean hulls, palm kernel meal, beet pulp and timothy hay. The NDSF contents in the diets were 9.02% (T1), 10.09% (T2), 12.42% (T3) and 14.63% (T4). In vitro dry matter digestibility (IVDMD) at 48 h was 7.4% higher for T4 compared to T1 (p<0.05). Total gas production at 48 h was 6.6% higher for T4 than T1 (p<0.05). CH4 production significantly decreased at 9 h and 12 h for T1 and T2 (p<0.05). At 48 h, CH4 production was 5.6% higher for T4 compared to T1 and 6.7% higher compared to T2 (p<0.05). At 12 h ans 24 h, the ammonia nitrogen concentration of T4 was approximately 33.1% and 40.4% lower, respectively, compared to T1 (p<0.05). The acetate to propionate ratio at 48 h was approximately 18.8% higher for T4 than T1 (p<0.05). From 9 h to 48 h, the proportions of butyrate and valerate were significantly higher for T4 (p<0.05). At 48 h, the dominant phylum in T4's rumen microbial community was Candidatus Thermoplasmatota Methanomassiliicoccus, an Archaea. Therefore, this study confirmed that increasing the NDSF content in growing Hanwoo cattle diets up to 12.42% increases IVDMD without increasing CH4 emissions, which is expected to positively impact Hanwoo productivity.

한우에게 급여하는 사료 내 에너지원의 종류에 따라 반추위 미생물의 아미노산 조성에 차이가 있는지를 조사하고자 본 연구를 수행하였다. 국내 한우 비육우 사육에 주로 이용되는 에너지원 사료인 옥수수(T1), 생미강(T2), 소맥(T3) 그리고 소맥피(T4)로 반추위 환경과 유사한 연속식 배양기를 이용하여 72시간까지 배양을 진행하였다. 배양이 진행되는 동안 6시간 간격으로 배양액의 발효 성상을 확인하였으며 pH, NH3-N이 일정하게 유지되는 것을 확인하였으며, 배양 종료 시점인 72시간대에 미생물체 단백질 합성량(MPS), 미생물의 아미노산 조성 및 미생물 균총 변화를 분석하였다. 배양액의 pH는 모든 처리구에서 배양 기간동안 5.5~7.0을 유지하였다. Total VFA 농도는 T1이 23.13 mM으로 가장 낮았고, T4가 29.93 mM으로 가장 높았다(p<0.05). A (acetate) :P (propionate) 비율은 T1이 1.48로 가장 낮았으며, T4가 2.81로 가장 높게 나타났다 (p<0.05). Butyrate는 T1이 2.37 mM으로 가장 낮았으며, T2, T3 그리고 T4는 4.37~4.58 mM으로 차이가 없었다(p<0.05). MPS는 T2 (332.5 mg/L)와 T3 (320.2 mg/L)가 높았고 T1 (137.5 mg/L)와 T4 (154.2 mg/L)로 낮게 나타났다(p<0.05). DGGE band 분석결과 모든 처리구는 57.5 % 이하의 유사도가 나타났다. 미생물의 총 아미노산 함량은 T1 (31.59 %)과 T3 (31.33 %)가 가장 높았으며, T2 (20.09 %)가 가장 낮았다 (p<0.05). 이는 급여된 사료 내 총 아미노산 함량과 반대되는 결과로 나타났다. 따라서, 본 연구에서 한우 급여 에너지원 사료에 따른 반추위 내 미생물 발효 특성과 미생물체 단백질 합성량이 미생물 군집에 영향을 미치며 이에 따라 미생물의 총 아미노산 함량에 영향을 미친다는 것을 확인하였다.

This in vitro study investigated the enhancement of rumen bacterial adhesion on a substrate to increase the digestibility of rice straw in Hanwoo cattle. The rice straw was pretreated with enzymes, probiotics, or ammonia, and the effects on the enhancement of bacterial adhesion and fiber degradation were analyzed using in vitro rumen fermentation. Enzyme treatment included spraying of cellulase and xylanase at 40 and 120 U per g of rice straw, respectively; Saccharomyces cerevisiae culture of 1.0×107 CFU was sprayed as a probiotic treatment per gram of rice straw; ammonia was sprayed at 0.3% per gram of rice straw. Following enzyme treatment, Fibrobacter succinogenes formed a higher adhesion colony than the control group (7.26±0.03 and 8.43±0.20) after 6h and 12h of in vitro culture (p<0.05), respectively. Attachment of Ruminococcus flavefaciens also increased following enzyme treatment (p<0.05) after 6 and 12 h compared to that of the control (5.18±0.06 and 6.60±0.15); and R. albus attachment showed a significant increase compared to that of the control (5.94±0.15) after 6 h of incubation (p<0.05). Probiotic treatment increased attachment of F. succinogenes in comparison with untreated rice straw after 6 h and 12 h of fermentation (p<0.05); R. flavefaciens attachment showed an increase only after 6 h of culture (p<0.05); R. albus was not affected. Attachment of F. succinogenes, R. flavefaciens, and R. albus increased with ammonia treatment after 6 h and 12 h (p<0.05). Dry matter digestibility was higher after the enzyme treatment (3.45±0.21 and 7.04±0.09) than in the control group(1.85±0.08 and 3.94±0.04) after 6 and 12 h of in vitro culture (p<0.05), respectively. It was also higher than that of untreated rice straw after probiotic and ammonia treatments (p<0.05). There was an increase in the enhancement levels of bacterial adhesion depending on the type of fibrolytic bacteria following enzyme, probiotic, and ammonia treatment. These treatments improved digestibility. This enhancement is considered to be greater following enzyme and ammonia treatments than with probiotics.

일반적으로 혈통 정보가 검증된 송아지의 경우 부모로부터 전달받은 유전능력을 통해 비육 후 출하 시에 우수한 도체 성적을 나타낼 확률이 상대적으로 높다고 알려져 있고, 이를 근거로 경매 시장에서 높은 가격대를 형성하고 있으나 이에 대한 과학적인 검증이 미비한 실정이다. 그러나 최근 친자확인 사업을 통해 과학적 검증을 위한 자료 수집이 가능한 상황이다. 따라서 본 연구는 2014년부터 2019년까지 경남 ‘ㄱ’지역 송아지를 대상으로 친자확인을 실시한 결과와 송아지의 경매 낙찰가 자료를 활용하여, 친자확인이 송아지 경매 낙찰가에 미치는 영향에 대해 분석하였다. 그 결과 2014년 친자 일치율이 64.6%였으나 6년간 지속적인 친자확인을 통해 2019년도에는 91.4%로 친자 일치율이 26.8% 상승하였음을 확인하였고, 이는 경남 ‘ㄱ’지역 농가의 혈통관리에 대한 인식이 높아진 결과로 한우의 자연적 개량이 이루어지는데 친자확인이 긍정적인 영향을 미쳤다고 판단된다. 또한 친자확인 일치 여부에 따른 송아지 경매 낙찰가의 경우 친자 일치된 송아지가 불일치된 송아지에 비해 경매 낙찰가가 약 34만원 높게 낙찰 되었고, 친자 일치된 송아지 내 성별에 따라 수송아지와 암송아지가 친자 불일치된 송아지 보다 각각 약 37만원, 22만원 높은 가격에 낙찰되었다. 따라서 본 연구와 추가적인 연구를 진행한다면 추후 농장별 계획 교배와 정확한 혈통관리를 통한 신뢰도를 높이는 것이 수익에 긍정적인 효과와 지역 단위로 지속적인 친자확인의 관리가 한우산업에 긍정적인 효과를 유발할 수 있다는 것으로 사료된다.

In the present study, we examined if deep uterine artificial insemination (DUAI) can improve the pregnancy rate of artificial insemination (AI) using epididymal spermatozoa (ES) in Hanwoo cattle. The estrus cycles of 88 Hanwoo cows were synchronized, and 17 cows were artificially inseminated using the DUAI method with ES, 20 cows were artificially inseminated via the uterine body (BUAI) method with ES, and as a control, 51 cows were inseminated by using the BUAI method with ejaculated spermatozoa from 1 proven bull after frozen thawing. The pregnancy rate of the DUAI method (58.8%) was higher than that of the BUAI method (25.0%, p = 0.0498). The motility of ES was examined immediately after thawing and after 3 and 6 h of incubation. The rapid progressive sperm motility of the control group was significantly higher than that of the ES group immediately after thawing and after 3 and 6 h of incubation (p < 0.05). The straight line velocity and average path velocity of the ES group after 6 h of incubation were significantly lower than those in the control group (p < 0.05). The linearity and amplitude of lateral head of ES were lower than those at 6 h (p < 0.05). The flagellar beat cross frequency and hyperactivation of ES were lower than the control spermatozoa immediately after thawing and at 3 h (p < 0.05). These motility parameters suggested that ES had a low motility and fertilization ability compared to the control spermatozoa. After frozen-thawing and 3 h of incubation, the percentage of live spermatozoa with intact acrosomes in the ES was significantly lower than that in ejaculated spermatozoa (p < 0.05). Our findings suggested that the DUAI method can overcome the low pregnancy rate of ES, despite the low motility, viability, and fertilization ability of ES.

Embryonic lethality due to recessive alleles is a major concern in livestock breeding programs. The Online Mendelian Inheritance in Animal (OMIA) is a database of reported recessive mutations in livestock that helps breeders to manage the segregation of these mutations in their population. Recessive alleles are lethal in the offspring of two carrier parents; therefore, identifying and eliminating carrier animals are critical for maintaining the breed. Hanwoo cattle is native to the Korean peninsula and is of great economic importance to Korea. Due to geographical constraints and the controlled breeding program with very few proven bulls, if not monitored periodically, the threat of segregation of recessive lethal alleles in the population remains high. Therefore, identifying potential carriers of lethal recessive alleles is critical in Hanwoo. In this regard, we genotyped 17,325 animals using bovine 50K Illumina SNP chip and also sequenced a further 311 animals which was mapped against the bovine reference genome sequence. We then used the OMIA database to identify reported recessive alleles and calculated the allele frequency of these mutations in the population to determine potential lethal alleles carried by the animals.

반추동물의 급여 단백질 효율성은 반추위 내 미생물 발효에 따른 우회단백질, 미생물체단백질, 사료 및 미생물체의 아미노산 구성 등에 의해 결정된다. 실험 1은 주요 단백질 사료원료 중 국내 한우 사육에 주로 이용되는 사료원료 15종[옥수수(남미), 옥수수(우크라이나), 단백피(국내), 단백피(중국1), 단백피(중국2), 대두박(국내), 대두박(미국), 대두박(브라질), DDGS(미국), 팜박(인도네시아), 채종박(캐나다), 루핀(미국), 미강(국 내), 주정박(국내), 타피오카(인도네시아)]의 반추위 내 단백질과 아미노산의 우회 수준을 측정하였다. 캐뉼라 장착 한우 암소를 이용하여 in situ 실험을 진행하였다. 우회 단백질 함량은 타피오카(인도네시아)에서 59.98%로 가장 높았다. 타피오카(인도네시아)는 총 우회 아미노산 함량이 73.73% 로 가장 높았으며, glutamic acid (Glu)와 alanine (Ala)이 72.17%, 75.23%로 가장 높았다. 실험 2에서는 실험 1과 같은 원료를 사용해 반추위 내 미생물 발효 특성에 따른 미생물체 아미노산 조성분석을 실시하였다. 실험 결과 채종박(캐나다)의 pH는 6.99 (p<0.05), 미생물 단백질 합성량은 326.53mg/100mL (p<0.05), NH3-N의 농도는 단백피(중국 1)가 48.20mg/100mL (p<0.05)로 높았다. 옥수수(우크라이나)의 총 VFA 농도는 97.92mM (p<0.05)이었다. 미생물의 총 아미노산 함량은 대두박(미국) 52.07%로 높았으며 아미노산 조성은 모든 시험 사료에서 Glu가 높았다. 따라서, 본 연구는 한우의 급여 단백질 사료원에 대한 반추위 내 우회단백질, 우회아미노산함량과 반추위 내 미생물 아미노산 조성에 대한 연구를 실시하였으며, 향후 한우 단백질 급여사료원에 대한 대사단백질(MP) 공급체계의 기초자료로 활용될 수 있을 것이다.

번식효율은 농가수입에 직접적으로 영향을 미치는 요인으로 암소뿐 만 아니라 씨수소의 번식효율은 중요한 경제형질로 여겨지고 있다. 본 연구에서 는 한우 씨수소에 대한 번식효율을 분석하기 위하여 2010~2017년에 전북지역 분만기록 62,284개와 이에 사용된 132두의 KPN에 따른 인공수정 수태율을 분석하였다. 종부차수(NAIPC)가 증가함에 따라 분만간격(CI), 공태기간(CCI)이 유의적으로 증가하였으며(P<0.05), 임신율은 낮아졌다. 첫 종부 임신율은 62.365%로 나타났으나, 3차 이후에는 48.147 이하로 급격히 낮아졌으며, 6차 이후에는 15.664% 이하로 낮아졌다. KPN과 인공수정사 모두 수태율에 크게 영향을 미치는 것으로 나타났다. KPN에 따른 수태율은 39.154~70.621%로 분석되었으며, 인공수정사에 따른 수태율 은 22.237~85.517%로 나타났다. 인공수정 실패 시 같은 KPN의 재사용율은 20% 내외로 특별한 경향은 보이지 않았다. 첫 종부 기록만을 이용하여 상대적 추정 수태율(ESCR)을 분석한 결과 KPN1041이 가장 높은 11.107%로 나타났으며, KPN1112는 가장 낮은 -20.591%로 나타나 31.698%의 차이를 보였다. 본 연구결과 인공수정사 뿐 만 아니라 전북지역에서 사용되고 있는 KPN에 따라 번식효율이 크게 영향 받을 수 있는 것으로 나타났다.

This study was performed to evaluate the effect of heat stress on the status of physiological responses, blood parameter, serum T3 and cortisol, and heat shock proteins (HSP 27, 70, and 90) of Hanwoo cattle. Six Hanwoo steers (242.8 ± 7.2 kg of BW) were housed in the climate-controlled respiration chambers. The experiment consisted of 7 days (control; 0 day) at thermoneutral (air temperature (Ta) of 15oC and relative humidity (RH) of 60%; temperature-humidity index (THI) = 64), and by 3 and 6 days (treatment groups) at heat stress (Ta of 35oC and RH of 60%; THI = 87). Body temperature of each parts (frank, rump, perineum and foot) and rectal temperature elevated in heat stress groups (3 days and 6 days) than the control group (0 day). Respiration rates increased in 3 days and 6 days (88.5 ± 0.96 bpm and 86.3 ± 0.63 bpm, respectively) from 0 days (39.5 ± 0.65 bpm). Feed intake significantly decreased in heat stress groups (3 days and 6 days, 3.7 ± 0.14 kg and 4.0 ± 0.15 kg, respectively) than the control group (0 day, 5.0 ± 0.00 kg). In addition, final BW significantly decreased in heat stress groups (3 days and 6 days, 211.8 ± 4.75 kg and 215.5 ± 3.50 kg, respectively) than the control group (0 day, 240.0 ± 25.00 kg). However, heat stress has no significant effect on blood parameter, serum T3 and cortisol. Nevertheless, heat stress increased HSPs mRNA expression in liver tissue, and serum concentration of HSPs. Despite Hanwoo cattle may have high adaptive ability to heat stress, our results suggested that heat stress directly effect on body temperature and respiration rate as well as serum and tissue HSPs. Therefore, we are recommended that HSPs could be the most appropriate indicators of Hanwoo cattle response to heat stress.

한국에 있어서 한우는 경제 동물일 뿐 만 아니라 중요한 유전자원 중 하나이다. 그러나 현재 한우의 번식 능력 개량을 위한 연구는 매우 미흡한 실정이다. 한우의 번식 능력에 대한 기초 자료를 확보하기 위해 전북지역(정읍시)에서 인공수정 된 암소 총 33,281두에 대한 105,017개의 번식기록(2010-2017)을 이용하여 임신기간(GP), 분만 후 첫 종부기간(CFSI), 분만 후 임신간격(CCI), 수태당 종부회수(NAIPC), 첫 종부 임신율 (FSCR)을 계산하여 분석에 활용하였다. 전체적으로 GP 는 287.602±4.797일, CFSI와 CCI는 각각 77.513±34.417 및 88.433±42.194일 이였다. 또한 FSCR는 62.365%였으며, NAIPC 는 1.411회로 나타났다. 2017년의 FSCR과 NAIPC는 각각 67.497% 및 1.344회로 2013년 62.366% 및 1.402에 비해 유의적으로 증가하였다(p<0.05). 가을과 겨울에는 번식기간이 더 길었으며, NAIPC는 봄과 여름에 비해 유의적으로 증가하는 것으로 나타났다(p<0.05). 3~7산차 암소의 경우 NAIPC가 1.323±0.669~1.339±0.689회로 다른 그룹에의 1.401±0.772~1.446±0.854회 보다 우수한 것으로 나타났다. 반면, 1산차 암소의 경우 FSCR와 NAIPC가 각각 60.217% 및 1.506±0.937회로 가장 저조한 것으로 나타났다. 본 연구 결과 한우의 번식효율은 산차에 따라, NAIPC는 계절에 따라 영향 받는 것으로 나타났으며, 전체적인 번식효율은 과거에 비해 지속적으로 향상되고 있는 것으로 나타났다.

The present study was conducted to evaluate the effects of high levels of nutrients on the growth performance, blood metabolites and carcass characteristics of Hanwoo cattle. Eighteen Hanwoo steers were fed two types of diets: 1) Nine animals were fed the conventional diet including typical levels of crude protein (CP) and total digestive nutrients (TDN), and 2) Nine animals were fed the treatment diet including high levels of CP and TDN. The average body weight (BW) and dry matter intake (DMI) were greater (P < 0.05) in the treatment group than in the conventional group at early and late fattening stages. Also, in the treatment group, the average daily gain (ADG) was greater (P < 0.05) at the late fattening stage. The serum total lipid and cholesterol levels were higher (P < 0.05) in the late fattening stage of treatment group. The carcass weight, total fat weight, longissimus muscle area and the grade of meat quality were also greater (P < 0.05) in the treatment group than the conventional diet group. This study demonstrates that high levels of CP and TDN exhibit a positive effect on the growth performance and carcass characteristics, indicating that high levels of CP and TDN can be used as a cost-effective feeding program for Hanwoo cattle by shortening the feeding period.

This study was conducted to investigate the optimal artificial insemination (AI) time with diagnostic kit at ovulation time. We already applied the patent about the protein in the cow heat mucose in external reproductive tract. And we would examine the accuracy for detection of cow heat by the kit produced with the protein. Evaluation of optimal heat detection was tried two time at 12 hrs and 24 hrs after the heat. And then, AI service also performed two times with no relation to the results of heat diagnosis by heat detection kit and pregnancy rates were checked with rectal palpation on 60th day after AI. Heat diagnostic results by kit in natural heat after 12 hrs in Hanwoo cows were showed 31.3~75.0% on positive in first heat detection and 33.3~100.0% on positve in second heat detection. In the 1st positive results were significant different (p<0.05), but 2nd positive were not. The results of heat detection showed different result on regional influence and individual cow effects. The pregnancy rates of first trial of heat detection were showed 34.4~78.7% on positive and 21.3~68.8% on negative after the diagnosis by heat detection kit. And the pregnancy rates of next trial of heat detection were showed 33.3~85.7% on positive and 14.3~66.6% on negative after the heat diagnosis. Both positive results of first trial and next trial also were showed significant different (p<0.05), but negative results were not. In positive result, first trial of total pregnancy rates was higher than the next trial of pregnancy, but there showed opposite results on negative results. In conclusion, the optimal heat detection kit is suitable to ordinary Hanwoo cows and it suggested that we have to improve the kit’s accuracy by detecting the materials like proteins related optimal AI time.

Cryopreservation of germ cells from genetically proven animals could be a source of restoration tools from the risk of extinction or disappearance of wanted characteristics. Using frozen semen, the genetic gains of Korean native cattle have been increased greatly for 70 years. The preservation of genetic resources as a form of frozen semen straw has limited availability due to the numbers. To circumvent this weakness of frozen semen, we tested two re-freezing methods with different initial thawing temperatures using frozen Korean proven semen and rare breed semen from albino, black and chikso breeders. It has been known that human sperm could resist to cryo-damages by repeated freeze-thaw cycles, but not for Korean proven bulls number (KPN) or for rare breeds. Total 7 frozen semem from brindled(2), black(1), Korean Albino(2) and KPN(1) bulls were used for our research. After thawing straws under 5°C/2min or 37°C/40sec with low temperature water bath and thermo jug, spermatozoa were re-diluted with triladyl diluents after first thawing and re-frozen. Sperm motilities were compared between animals and treated groups after re-thawing. Mean values of motility and viability of refrozen/thawed sperm for expansion of the number of straws were significantly higher in 5°C than in 37°C (P< < 0.05). However, the activity of viable sperm thawed at 5°C was significantly decreased after first and second thawing. It is estimated that re-freezing of frozen semen from rare Korean native cattle is possible with resistant properties of survived spermatozoa.

This study aimed to indentify single nucleotide polymorphisms (SNPs) in exon region of the glycerol-3-phosphate dehydrogenase 1 (GPD1) gene and to evaluate their associations with meat yield and quality traits in Hanwoo (Korean cattle). Two SNP markers, g.2766C>T and g.5105A>G were identified in the exons 5 and 8, respectively. Genotyping of the two SNPs was carried out using PCR-RFLP analysis in 309 Hanwoo steers to evaluate their associations with meat yield and quality traits. As a result, g.2766C>T in exon 5 was significantly associated with carcass weight (CW) and marbling score (MS). Animals with the CC genotype of g.2766C>T had heavier CW than those with the CA or AA genotype. Animals with the CC genotype of g.2766C>T also had higher MS than those with the CA or AA genotype. Additive effect was also observed with CW and MS traits. We constructed haplotypes by linkage disequilibrium analysis and analyzed association between haplotypes and meat yield and quality traits. Haplotype of GPD1 gene was associated with CW. As a result, animals with CA haplotype had heavier CW than TG haplotype. These findings suggest that the SNPs of bovine GPD1 gene may be a useful molecular marker for selection of meat yield and quality traits in Hanwoo.

The Korean native cattle, Hanwoo, is the most popular breed of beef cattle in Korea. However, the reproductive performance data are limited although reproduction is one of the most economically and biologically important in beef production. Therefore, this study was undertaken to investigate reproductive performance parameters including calving interval, parity for life time production. Data collected from 206,827 calvings were analyzed. There were no significant differences in calving interval and gestation days as parity increased from 2nd and 13rd parity cow, from spring to winter. However, we found a dramatic increase in calving interval after year 2000. About 1 month were increased per year ( y = 30.578x + 344.45 R² = 0.9157). Interestingly, we observed that parities for life time can be affected by birth weight. Calves with 23 kg at birth showed highest parities, 3.4±2.0 times. In summary, this study provides valuable data on reproductive performance of Hanwoo and the data presented here can be used as a standard target for optimising and enhancing reproductive performance.