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.

South Korea has a temperate climate with four distinct seasons. However, summers are extremely hot and humid, which negatively affects industrial animal production. Hanwoo are native cattle that have traditionally been raised in the natural environment of Korea. The present study investigated the effects of birth and lactation season on the birth and weaning weights of Hanwoo calves. Data were collected from 100 local breeding farms between 2016 and 2021. A total of 56,970 (males, 29,530; females, 27,440) Hanwoo calves were classified according to sex or birth and weaning season (March–May, spring; June–August, summer; September– November, fall; and December–February, winter). The birth weight of Hanwoo calves differed according to the birth season. As such, birth weight of the summer-born calves was the lowest. Additionally, the 90-day weaning weight was positively correlated with birth weight. Interestingly, however, the 90-day weaning weight was not related to the birth season but was related to the 2-month seasonal effect during the lactation period. Furthermore, the 90-day weaning weight was the lowest during the summer lactation period. In the beef cattle industry, daily weight gain is an important economic characteristic related to feed efficiency and growth. Our findings will contribute the management of Hanwoo cattle and analysis of changes in economic characteristics due to high temperatures.

본 연구는 6개 핵돈군생산농장(Great grand parents, GGP)에서 2015년 이후 태어난 Landrace종과 Yorkshire종의 두 품종에 대하여 생시체중 (Birth weight; BW), 복당평균생시체중(Mean of litter birth weight; MBW0)과 변이계수(Coefficient of variation in MBW0; CVMBW0) 및 산자수(Litter size) 등에 대한 유전모수를 추정하였다. Landrace종에서 총산자수(Total number of piglets born; TNB), 생존산자수(Number of piglets born alive: NBA), 복당평균생시체중 및 복당평균생시체중 변이계수의 유전력은 각각 0.14, 0.09, 0.33 및 0.16. Yorkshire종에서는 각각 0.11, 0.99, 0.28 및 0.07로 추정되었다. 산자수와 복당평균생시체중 간에는 부(-)의 상관관계를 나타내었으며, 복당평균생시체중과 변이계수사이의 표현형상관과 유전상관이 두 품종에서 모두 –0.40에서 –0.45로 높게 나타났다. 자돈 생시체중에 대한 균일도를 개량하기 위해서는 복당평균생시 체중(MBW0)과 복당평균생시체중변이계수(CVMBW0)를 선발지수식에 포함시키는 것이 바람직하다고 생각된다.

Purpose: This study aimed to identify the current status and needs of nursing education for extremely low birth weight (ELBW) infants in Korea, and to obtain preliminary information to develop a simulation-based educational program on nursing care for nurses in the neonatal intensive care unit (NICUs). Method: Descriptive survey design was adopted in developing an ELBW infant nursing education program. Data were collected from 71 NICU nurses using a questionnaire survey. Statistical Package for the Social Science (SPSS) (version 23) for windows was used to analyze the frequency, percentage, mean, and standard deviation of the collected data. Results: Seventy-one nurses working in the NICU reported that majority of them (76.1%) had experience in ELBW infants’ nursing education. The following were highly recommended for simulated training by NICU nurses: nursing intervention immediately after birth in ELBW infants (69.0%), NICU‘ initial admission nursing (66.2%), and frequency response coping nursing (57.7%). Conclusion: The study revealed that there is a considerable need for the ELBW infants nursing education program. The results of this survey will ultimately provide a basis for developing simulation-based ELBW infants nursing training programs for NICU nurses.

본 연구는 두록종 돼지의 복당 생시체중 형질(복당 생시체중 평균, 복당 생시체중 표준편차)과 산자수 형질(총 산자수, 생존 산자수, 사산두수)의 유전모수를 추정하고 이들 형질간의 상관관계와 개량방안을 알아보기 위해 실시하였다. 분석에는 국립축산과학원에서 2006~2016년 사이에 분만한 두록 모돈 1,081복의 자료를 이용하였다. 분석형질은 복당 생시체중 평균(ABW), 복당 생시체중 표준편차(BWSD), 총 산자수 (NB), 생존 산자수(NBA) 및 사산두수(NBD)이다. 유전모수 추정은 다형질 개체모형을 이용하였다. 각 형질에 대한 유전력은 복당 생시체중 평균(ABW), 복당 생시체중 표준편차(BWSD), 총 산자수(NB), 생존 산자수(NBA) 및 사산두수(NBD)에 대해 각각 0.32, 0.13, 0.11, 0.10, 및 0.06으로 추정되었다. 복당 생시체중 평균(ABW)과 복당 생시체중 표준편차(BWSD)는 0.75의 높은 정의 유전상관을 보인 반면 생존 산자수(NBA)와 복당 생시체중 평균(ABW), 복당 생시체중 표준편차(BWSD)간의 유전상관은 각각 –0.26, -0.40로 생존 산자수(NBA)가 증가함에 따라 복당 생시체중 평균과 복내 개체간 체중의 표준편차는 감소하는 것으로 나타났다. 생존 산자수(NBA)와 사산두수(NBD)간의 유전상관은 0.24로 생존 산자수(NBA)가 증가하면 사산두수(NBD)도 증가하는 유전적 관계를 나타내었다. 한편 복당 생시체중 평균(ABW)과 복당 생시체중 표준편차(BWSD), 사산두수(NBD), 총 산자수(NB)간의 유전상관은 각각 0.75, 0.81과 0.08로 추정되어 복당 생시체중 평균(ABW)이 증가하면 총 산자수(NB)의 큰 변화 없이 복당 생시체중 표준편차(BWSD), 사산두수(NBD)가 증가하는 것으로 나타났다. 본 결과로 미루어 볼 때 유전력이 높은 복당 생시체중 평균(ABW)은 직접선발을 통한 빠른 개량이 가능한 반면 복당 생시체중 표준편차(BWSD), 총 산자수(NB), 생존 산자수(NBA) 및 사산두수(NBD) 형질은 직접선발을 통한 개량 효과가 낮을 것으로 판단된다. 특히 자돈 생시체중의 균일도를 개량하고자 한다면 복당 생시체중 표준 편차(BWSD)에 대한 직접선발 방법과 더불어 복당 생시체중 평균(ABW)을 이용해 간접선발하는 방법 또한 이용 가능할 것으로 사료된다.

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.

돼지의 생시체중은 생존율과 폐사율에 밀접한 관련이 있어 양돈산업에서 자돈 관리와 직결된 중요한 경제형질이다. 본 연구는 Genome-Wide Association Study(GWAS) 분석을 통해 순종 랜드레이스의 생 시체중과 관련된 위치상 후보유전자 탐색을 실시하였다. 생시체중의 유의적 관련 분석 결과, genomewide suggestive level에서 유의성 있는 single nucleotide polymorphism(SNP) marker는 3번 염색체 (ASGA0098921, P=2.41×10-5)와 4번 염색체(H3GA0013451, P=2.47×10-5)에서 각각 1개씩 동정되었다. 이들 SNP marker가 위치한 3개의 유전자(LOC110260055, LOC100156472, LOC100157689)들은 순종 랜드레이스 생시체중의 위치상 후보 유전자이며, 이들 유전자 정보를 이용해서 순종 랜드레이스 생시 체중을 선발할 수 있는 기초 연구 자료가 될 것으로 사료된다.

This study was conducted to find out the environmental, service sire and genetic effects for reproductive trait in certain purebred of pigs on Landrace and Yorkshire, and to suggest selection indicator which is to improve genetic capability on reproductive traits. There are five traits used on this analysis which are total number of born (NBT), number of born alive (NBA), piglets weight within litter (LW), average of birth weight on piglets within litter (ABW) and variation of birth weight on piglets within litter (VBW). With these data, the mixed model was established using 10,342 records collected from 2,527 sows of Landrace and 13,817 records collected from sows of 3,056 Yorkshire breeds and the variation of random effects and the genetic parameter were estimated by the REML method including service sire effects, permanent environmental effects and sow genetic effects. Due to characteristics of closed nucleus herd for using data on this study, given that it has been isolated breeding for about 19 years that progressed over 16 generations, genetic analysis was performed on all of these data and partial data of the current genetic group in which animals were born after 2011. The effects of service sire were estimated to be less than about 8% of total variation in all traits considered in the analysis. Permanent environmental effects were estimated about 2~14% of total variation in all traits considered. The heritability, which is the ratio of genetic variance among the total variance, was estimated to be 20~35% for LW and ABW in Landrace and Yorkshire, while it was about 10~14% for NBT. The genetic correlations between NBT and LW were 62~74% and between NBT and ABW were –28~-7%. Therefore, indirect selection for improving litter size could be possible with considering LW. Whereas, the genetic effect of the service sire effects for litter traits would be trivial.

Swine industry has been focusing selection of excellent breeding pigs for post decades. This result is created to superior breeding sows with larger litter size, which are leads to low birth weight piglets (LBW) because of intrauterine growth retardation. The LBW on development of pigs have well known to postpone growth performance and to disrupt body metabolisms than normal birth weight piglets (NBW). However, effect of LBW on reproductive functions is very not documented. Therefore, this study was conducted to identify effect of birth weight on reproductive function in the LBW compared with normal birth weight piglets (NBW) by RNA sequencing and pathway studio. The experimental animals utilized 3d old LBW (0.96±95.07 kg, n=4) and NBW (1.69±83.39 kg, n=4). The differentially expressed genes were approximately 800 genes above 2 fold. The genes were related to steroid hormone synthesis, estrogen receptors signaling and growth and proliferation of cells. These results may be suggested to affect development of reproductive organ. However, our data are restricted using young experimental animals.

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

The objective of this study was to estimate the genetic and phenotypic parameters of litter size and birth weight traits in three Korean black goat lines (Dangjin, Jangsoo and Tongyung) raised at the Animal Genetic Resources Station (AGRS) of the National Institute of Animal Science (NIAS). A total of 1,861 records collected from 2001 to 2013 were used for analyses with single trait animal models. The average litter size of Dangjin line was the largest (1.72 kids) and the average birth weight of Jangsoo line was the heaviest (1.88 kg) among the three lines. Heritability estimates of litter size and birth weight were 0.07 and 0.26, respectively. The average breeding value of litter size and that of birth weight of Jangsoo line were the greatest of all three lines, 0.15 heads and 1.88 kg, respectively. The correlation coefficients between phenotypic values and breeding values of litter size in the lines of Dangjin, Jangsoo and Tongyung were 0.054, -0.031 and 0.131, respectively. The correlation coefficients between phenotypic values and breeding values of birth weight in the lines of Dangjin, Jangsoo and Tongyung were 0.570, 0.454 and 0.521, respectively. The phenotypic correlation and breeding value correlation between litter size and birth weight were 0.031 and 0.003 in Dangjin line, -0.038 and 0.094 in Jangsoo line, and 0.109 and 0.121 in Tongyung line, respectively. These data suggest that the genetic parameters estimated for litter size and birth weight in this study could be used to improve genetic potentials of Korean black goats in industrial level

This study investigated the effect of birth weight on the fertility of Holstein heifers. Growth parameter (body weight) was measured at birth. Calves were analyzed as three subgroups: low (L), average (A) and high (H) birth weight (BW) calves. LBW calves were born 10 kg lighter than HBW calves. Fertility data collected included age at first breeding (AFB), number of services per conception, pregnancy rate to first artificial insemination (AI), and age at first calving (AFC). Primiparous calves in HBW are smaller compared to multiparous cows (18.3% versus 48%). Although not significantly different, LBW offspring appeared to breed faster over the service period compared with the ABW offspring that bred three weeks later on the average. The mean pregnancy rate to first AI for LBW heifers was higher (60%) than ABW (48%) and HBW (45%). HBW cows required more services per conception (2.1) than the LBW (1.7) and ABW (1.9). There were significant differences (p<0.05) in age at first calving among the different calving birth weights. Smaller birth size did not have any subsequent adverse effects on fertility. HBW offspring were more likely or tend to have worse fertility parameters.

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.