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.

본 연구는 2006년부터 2016년 사이에 강원도 축산기술연구소에서 출생한 한우 송아지 1,069두로부터 조사된 이유시 체중과 임신기간, 생시체중 및 포유기 일당증체량 및 이유시 체중을 이용하여 단순상관, 다중 회귀 및 경로분석 등을 통해 이유시 체중과 임신기간, 생시체중 및 포유기 일당증체량 간의 상관 관계를 규명하였다. 통계분석은 조사된 원 성적을 이용하여 실시하는 동시에 조사된 원 성적을 송아지 출생 연도-계절, 송아지의 성, 어미의 산차 및 이유일령(포유기 일당증체량과 이유시 체중에만 해당) 등과 같은 환경효과에 대해 보정한 값인 잔차를 이용해서도 실시하였다. 조사된 형질들 간의 상관계수는 모두 양수였는데, 임신기간은 생시체중과의 잔차상관계수가 +0.315로서 중정도 크기였던 반면 포유 기 일당증체량이나 이유시 체중과의 잔차상관계수는 각각 +0.039와 +0.130으로서 작거나 0에 가까운 값이었다. 이유시 체중은 포유기 일당증체량과의 잔차상관계수가 +0.949로서 생시체중과의 상관계수인 +0.323보다 컸다. 잔차를 이용한 경로분석 결과 이유시 체중의 변이에 미치는 임신기간, 생시체중 및 포유기 일당증체량의 전체 기여도는 각각 0, 0.095 및 0.892로 나타났다. 본 연구 결과, 임신기간, 생시 체중 및 포유기 일당증체량 중에서 포유기 일당증체량이 이유시 체중의 변이에 가장 큰 영향력을 미치는 형질인 것으로 나타났다.

The objective of this study was to identify the phenotypic relationships among calving difficulty, calf birth weight and gestation length of Holstein dairy cattle under the environment of Korea. A total of 1,834 calving records collected by Dairy Science Division of National Institute of Animal Science, RDA from 2000 to 2014 was analyzed. General linear multivariate models for calving difficulty scores (CD: 1=no assistance, 2=minor assistance, 3=two to three persons assisted, 4=more than three persons assisted, 5=cesarean section), calf body weight at birth (BW), and gestation length (GL) included fixed effects of year and season (spring, summer, autumn, winter) of births (YS), sex of calves, and parity. For GL and BW, all three fixed effects (YS, sex of calves, parity) were significant (p<0.05). For CD, the effects of YS and sex of calves were significant (p<0.05). Bull calves were born with heavier BW by 3.18 kg, with greater CD by 0.18 point and with longer GL by 0.6 days than heifer calves. The least squares mean of BW was the heaviest at the third parity (44.1 kg) compared to those at the first, the second and the fourth parities or later (41.3-41.9 kg). The least squares mean CD at the first parity was 1.74 point, which was higher than CD at the second and later parities (about 1.68 points). Phenotypic correlation (partial residual correlation) between GL and BW was 0.36. But those between GL and CD and between BW and CD were -0.03 and 0.04, almost zeros. To conclude, we observed higher incidence of calving difficulty in the first calving than in the later ones. Further investigation on the relationships between calf’s birth weight and calving difficulty is needed

본 연구는 OPU 유래 한우 수정란을 이식한 대리모의 품종이 임신 기간과 산자의 생시 체중에 미치는 영향을 분석하고자 6~7일차 OPU 유래 한우 체외수정란을 한우와 젖소 대리모에 이식하여 산자를 생산하였다. 1. 대리모에 따른 평균 임신 기간(젖소: 일, 한우: 일)과 산자의 생시 체중(젖소: , 한우: )에서 유의적인 차이가 없었다. 2. 임신 기간은 수송아지를 생산한 대리모(한우: 일, 젖소: 일)가 암송아지(한우: 일, 젖소: 일)를 임신한 대리

The increase in the total number of cows on farms, which breed Korean Native Cattle (KNC), is associated with many problems. In particular, the services per conception and calving interval have increased. In this study, we examined the effect of dietary supplementation with vitamin and mineral complex on the estrus rate, pregnancy rate, gestation length, and birth weight of KNC calves. Multiparous or primiparous KNC were divided into 3 groups with 40 heads per group. Experimental group 1 was administered a consisting of 35,000 IU vitamin A, 100 IU vitamin E, 200 mg -carotene, 200 mg Zn methionine, and 1.5 mg Se. Experimental group 2 was administered a vitamin complex (100 g/day) consisting of 100 IU vitamin E and 200 mg -carotene. In the case of multiparous KNC, the estrus detection rate in the control group was 90.0% and those in the experimental groups were 75.0% to 95.0%. However, the first-service pregnancy rate after parturition in the control group was 41.2%, which was significantly lower than that in the experimental groups (71.0% to 76.7%; p<0.05). The average duration of pregnancy in the group supplemented with the vitamin complex was days, which was similar to that in the case of the control group. The birth weight of calves from cows fed with vitamin complex was 25.3 to 27.0 kg, which was similar to that in the case of the control group (25.2 to 26.0 kg). In the case of primiparous KNC, no differences in the estrus rate, pregnancy rate, gestation length, or the birth weight of calves were noted between the groups. Thus, dietary supplementation vitamin and mineral complex have no effect on the reproductive efficiency in primiparous cows, but the pregnancy rate was observed to have increased in multiparous KNC with these supplements.

본 연구는 체세포 복제 한우 송아지의 생산에서 생시체중과 생존성과의 관계에 대하여 살펴보고자 실시하였다. 293두의 한우 대리모에 580개의 복제란을 이식하였다. 복제란의 임신율은 이식 후 50일까지 72.3%로 높았으나, 이후 급격하게 감소하였다. 평균 임신 기간은 복제 송아지에서 287일(279~295일)이었으며, 인공수정 송아지도 287일(255~293일)로 각각 나타났다. 복제 송아지의 생시체중(30.3kg)은 인공수정 송아지(23.7kg)에 비하여 유의하게 높은 것으로 나타났다(p<0.05). 자연분만(n=17, 29.9kg)과 제왕절개(n=14, 32.3kg)로 태어난 복제 송아지의 생시체중은 차이가 없었다. 하지만, 생후 175일 이전에 사망한 복제 송아지(n=18, 32.8kg)의 생시체중이 175일 이상 생존한 복제 송아지(n=11, 28.3kg)보다 유의적으로 높게 나타났다(p<0.05). 흥미로운 점은 생시체중이 15kg 이하(n=5) 또는 35kg 이상(n=9)인 복제 송아지들은 모두 생후 175일 이전에 폐사하였다. 생후 175일 이전에 폐사한 복제 송아지들(n=20)의 사망 원인은 미성숙 개체 2두(10.0%), 폐와 간 이상 2두(10.0%), 폐의 원인 4두(20.0%), 기형 4두(20.0%), 출생 후 급사(sudden death syndrome) 4두(20.0%) 및 기타 원인불명이 4두(20.0%) 등으로 분류되었다. 이상의 결과를 종합하여보면, 복제 송아지의 정상 생시체중이 6개월 이상을 생존하는데 가장 중요한 요소들 중의 한 가지임을 확인하였다.

This study was carried out to establish an effective system for embryo transfer of techniques by analyzing several factors affecting the gestation length and the weight changes of calves produced from embryo transfer in Korean cattle. The results obtained in study on factors affecting the gestation length and the weight changes of calves produced from embryo transfer were as fallow; 1) The gestation length and the birth weight did not differ between male and female, but the weight changes after birth were remarkablely different between sex(P<0.05). 2) The gestation length between heifers and cows was not different, and body weights at birth and 6 months were remarkabley heavy in cows(P<0.05). Weight changes after 6 months were not different. 3) The gestation length and the birth weight were significantly different between the single and twin calving (P<0.05). Weight of twin at 6 and 12 months were remarkabely light. 4) Calving seasons did not affect the gestation length the and the birth weight. Weaning weight was significantly heavy(P<0.05), but weight changes after weaning were no different among the calving seasons. Conclusivley, this results suggest that cows will be better when considering growth of calves and twin produced from embryo trnsfer in Korean cattle.

This study was conducted to determine the main effects of the parity and farrowing season on gestation length and newborn pigs on the basis of the data obtained from 234 litters of Landrace breeds raised at an integrated swine farm in Kyunggy province from January 1991 to December 1992. The results obtained are summarized as follows ; 1. The average gestation length was 115.37 days, and 114.64 days of 8th parity and over was shorter than those of other parities. 2. The averages of litter size and litter size alive per sow were 9.91 and 9.50 heads. The litter size horn at 1st parity was smaller than at other parities, and the litter size in spring was larger than in summer, autumn or winter. 3. The averages of birth weight per litter and pig were 13.53 kg and 1.37 kg. The effect of farrowing season for each litter weight(p<0.01) and pig weight(p<0.05) at birth was significantly higher in spring than other seasons. 4. Incidence of malformation and stillbirth at birth was 4. 10%, and it at 8th parity and over showed the highest rate(7.50%).