• 제목/요약/키워드: Gestation length

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Genetic parameter analysis of reproductive traits in Large White pigs

  • Yu, Guanghui;Wang, Chuduan;Wang, Yuan
    • Animal Bioscience
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    • 제35권11호
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    • pp.1649-1655
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    • 2022
  • Objective: The primary objective of this study was to determine the genetic parameters for reproductive traits among Large White pigs, including the following traits: total number born (TNB), number born alive (NBA), litter birth weight (LBW), average birth weight (ABW), gestation length (GL), age at first service (AFS) and age at first farrowing (AFF). Methods: The dataset consisted of 19,036 reproductive records from 4,986 sows, and a multi-trait animal model was used to estimate genetic variance components of seven reproductive traits. Results: The heritability estimates for these reproductive traits ranged from 0.09 to 0.26, with the highest heritability for GL and AFF, and the lowest heritability for NBA. The repeatabilities for TNB, NBA, LWB, ABW, and GL were ranged from 0.16 to 0.34. Genetic and phenotypic correlations ranged from -0.41 to 0.99, and -0.34 to 0.98, respectively. In particular, the correlations between TNB, NBA and LBW, between AFS and AFF, exhibited a strong positive correlation. Furthermore, for TNB, NBA, LBW, ABW, and GL, genetic correlations of the same trait between different parities were moderately to strongly correlated (0.32 to 0.97), and the correlations of adjacent parities were higher than those of nonadjacent parities. Conclusion: All the results in the present study can be used as a basis for the genetic assessment of the target population. In the formulation of dam line selection index, AFS or AFF can be considered to combine with TNB in a multiple trait swine breeding value estimation system. Moreover, breeders are encouraged to increase the proportion of sows at parity 3-5 and reinforce the management of sows at parity 1 and parity ≥8.

Cloning and Characterization of Porcine Uroplakin II Gene

  • D. N. Kwon;H. K. Shin;C. K. Hwang;D. W. Ok;Kim, J. H.
    • 한국동물번식학회:학술대회논문집
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    • 한국동물번식학회 2001년도 춘계학술발표대회
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    • pp.19-19
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    • 2001
  • Mammalian urothelium undergoes unique membrane specialization by making the asymmetric unit membrane (AUM) that is covered with the apical cell surface during terminal differentiation. The AUM contains several major integral membrane proteins including uroplakin Ia, Ib, II and III. The genes for uroplakins have been cloned from humans and mice, but not from porcine. In this study, we report the cloning of the UPII genomic DNA, which codes for the full length open reading frame for the uroplakin II protein. The deduced amino acid sequence encodes of a hydrophobic NH$_2$-terminal peptide, a prosequence, and a mature protein. The prosequence contains three potential N-glycosylation sites and a RGRR cleavage site that may be involved in uroplakin II processing and maturation. Northern and immunohistochemistry analyses showed that the porcine UPII gene is only expressed in urothelium and that the protein was specifically localized in urothelial superficial cells. A 2kb of upstream in the promoter sequence contains multiple transcription factor binding sites, including GC-box, SPI, AP2, and GATA-box sites, but not for TATA or CAAT-box sequences. Comparison of the porcine UPII promoter sequence with that of the murine by MEME system presented two conserved motifs, suggesting a cis-acting regulatory role for the conserved sequences. Sequence homology between two species in motif A and B was 79% and 80% respectively, although their relative locations were different. During the gestation, mouse bladder at estrus stages and day 10 after parturition showed higher UPII expression, while showed lower expression at peri-implantation stage. Taken together, our results showed that the porcine UPII gene was expressed highly and specifically in the bladder urothelium and that steroid hormones for implantation changed the expression of UPII in the bladder, although the biological significance of UPII remains to be not determined.

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임신초기 모체의 엽산영양상태와 동 영향인자 (Maternal Folate Status and Its Influencing Factors in Early Pregnancy)

  • 이정아;이종임;임현숙
    • 한국식품영양과학회지
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    • 제33권2호
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    • pp.331-338
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    • 2004
  • 임신초기 모체의 엽산영양은 태아의 신경관 손상을 예방하는 측면에서는 물론이고 엽산 필요량이 증가하는 임신후기를 대비한다는 점에서도 중요하다. 그러므로 본 연구에서는 임신초기에 있는 151명의 임신부들을 대상으로, 이들이 식사를 통해 얼마의 엽산을 섭취하는지를 조사하고, 혈청과 적혈구의 엽산 농도와 혈장 호모시스테인 농도를 분석하여 엽산영양상태를 평가하고, 이들의 엽산영양상태에 영향을 미치는 인자들이 무엇인지 분석하고자 하였다. 본 연구대상자의 조사당시 임신기간은 9.1$\pm$2.3주이었으며, 초산부가 46%이었고 나머지는 경산부이었다. 에너지 및 엽산 섭취량은 각각 1559$\pm$589 ㎉/day 및 230.8$\pm$145.2 $\mu$g/day로 각 권장량의 72.5%및 46.2%로 낮았다 혈청과 적혈구의 엽산 농도는 각각 5.5$\pm$1.9 ng/mL 및 266.6$\pm$75.0 ng/mL으로, 연구 대상자의 7.8%가 혈청 엽산 수준이 3 ng/mL미만인 결핍상태에 해당하였고 60.3%는 경계역(3∼5.9 ng/mL)에 속하였으며, 적혈구 엽산 농도가 l57 ng/mL미만인 결핍상태에는 4.3%가 해 당하였다. 그러나 혈청 호모시스테인 농도는 정상범위이었다. 따라서 본 연구대상자의 엽산영양상태는 비교적 양호하다고 판정되었다. 혈청 엽산 농도에 영향을 끼칠 수 있는 유의한 인자는 건강상태점 수(+), 혈장 호모시스테인 농도(-), 연령 (-), 임신기간(-) 및 엽산 섭취량(+) 순으로 그 영향력이 높았고, 적혈구 엽산 농도의 영향인자는 교육수준(-), 혈장 호모시스테인 농도(-), 지난번 출산 영아의 출생시 신장(+),연령(-)및 에너지 섭취량(+)이었고, 혈장 호모시스테인 농도의 영향인자는 지난번 출산 영아의 출생시 신장(-), 경제수준(+),혈청 엽산 농도(-)와 임신전 체중(+)이었다. 이러한 결과는, 혈장이나 적혈구의 엽산 농도나 혈장 호모시스테인 농도를 분석하지 않고도, 임신초기에 있는 모체의 엽산영양상태를 개략적으로 판정하는데 있어 주관적으로 평가한 불량한 건강상태, 높은 교육수준 또는 경제수준, 지난번 출산에서 작은 체위의 영아를 출산한 경력, 고연령 또는 엽산이나 에너지섭취량 부족을 위험 인자로 활용할 수 있음을 시사한다. 아울러 임신기간이 진행되었을수록 엽산영양상태가 저하되었을 가능성이 있음도 나타내준다. 앞으로 임신초기 임신부의 엽산영양상태를 어떤 위험인자를 몇 가지나 가졌느냐에 따라 평가하는 연구결과가 나와야 이들 위험 인자의 실용성 을 확인할 수 있을 것이다. 그러나 우선 이들 위험 인자를 많이 지닌 임신부라면 임신초기부터 엽산 섭취량을 늘리거나 엽산보충제 섭취를 일찍 시작하는 등의 방법으로 엽산영양상태를 양호하게 유지하도록 하는 것이 바람직할 것이다.

한우의 번식형질에 대한 환경요인의 효과 (Effects of Environmental Factors on Reproductive Traits in Korean Cattle)

  • 한광진
    • Journal of Animal Science and Technology
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    • 제44권2호
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    • pp.191-200
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    • 2002
  • 본 연구는 1986년부터 1995년도 사이에 한우개량단지의 한우 암소에 대하여 조사된 번식성적에 근거하여 한우의 번식형질에 미치는 환경요인의 효과를 추정하기 위하여 실시하였으며, 분석된 결과를 요약하면 다음과 같다. 1) 평균능력에서 초종부일령은 466.11${\pm}$5.72일, 초임일령은 480.10${\pm}$6.15일, 초산일령은 742.79 ${\pm}$7.48일, 분만후 초종부일령은 64.97${\pm}$1.42일, 공태일수는 72.06${\pm}$1.73일, 번식간격은 355.93 ${\pm}$1.92일, 임신기간은 285.38${\pm}$0.42일 및 수태당 종부회수는 1.21${\pm}$0.02회였다. 2) 지역별 각 형질에 대한 범위는 초종부일령은 447.62${\pm}$5.94-490.72${\pm}$5.94일, 초임일령은 464.27${\pm}$6.38-505.20${\pm}$6.39일, 초산일령은 721.91 ${\pm}$ 7.85-772.75${\pm}$7.80일, 분만 후 초종부일령은 62.27${\pm}$1.55~68.97${\pm}$1.74일, 공태일수는 69.74${\pm}$ 1.97-74.36${\pm}$2.27일, 번식간격은 352.71${\pm}$2.18-359.64${\pm}$2.09일, 임신기간은 284.52${\pm}$0.42-286.04 ${\pm}$0.47일 및 수태당 종부회수는 1.11${\pm}$0.02-1.30 ${\pm}$0.02회였다. 3) 초종부일령은 혈통등록우가 가장 길었고 상위등록일수록 일령이 빨라지는 경향이 있 었다. 수태당 종부회수는 상위등록우로 갈수록 종부회수가 많게 추정되었다. 4) 분만후 초종부일수는 2산차에서 가장 길었으며 산차가 진행될수록 줄어드는 경향을 보였다. 수태당 종부회수는 산차가 진행될수록 적어지는 경향을 보였다. 5) 분만년도가 1987년부터 1995년까지 경과할수록 분만후 초종부일수, 공태일수 및 번식 간격이 길어지고 수태당 종부회수는 많아지는 경향이 있었다. 6) 분만후 초종부 일수, 공태일수 및 번식간격은 봄과 여름에 분만한 소들에서 가을과 겨울에 분만한 소들에 비하여 다소 짧게 추정되었다. 수태당 종부회수는 봄과 여름에 분만한 소들에 비하여 가을과 겨울에 분만한 소들에서 더 많은 경향이 있었다.

진도개에서 혈장 progesterone 농도측정에 의한 배란시기 및 교배적기의 추정 (Estimation of the time of ovulation and mating based on plasma progesterone concentrations in Korea Jin-do bitches)

  • 손창호;강병규;최한선;이나경;신창록;한호재;윤용달
    • 대한수의학회지
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    • 제37권4호
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    • pp.899-909
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    • 1997
  • The aim of this study was to assess the estimates of the time of ovulation and mating derived by plasma progesterone concentration. The 40 mature Korea Jin-do bitches were monitored to determine the plasma progesterone concentrations from proestrus to parturition. Gestation length in the 30 pregnant bitches was $63.9{\pm}2.3$ ($mean{\pm}SD$) days in multiparous bitches and $61.8{\pm}3.6$ days in primiparous bitches when Day 0 was timed from the first day of male acceptance, and $61.4{\pm}1.8$ days and $61.3{\pm}2.7$ days when Day 0 was timed from the day of first mating, respectively. Also, gestation length was $63.1{\pm}1.4$ days, $62.4{\pm}1.1$ days and $61.5{\pm}0.9$ days in multiparous bitches, and $62.6{\pm}1.4$ days, $62.4{\pm}2.0$ days and $61.6{\pm}2.3$ days in primiparous bitches when Day 0 was timed from the day that plasma progesterone concentration was first increased above 2.0, 3.0 and 4.0ng/ml, respectively, and $53.8{\pm}3.1$ days and $54.8{\pm}2.6$ days when Day 0 was timed from the last day of male acceptance, respectively. In 30 pregnant bitches, plasma progesterone concentration was $0.2{\pm}0.2ng/ml$ in multiparous bitches and $0.7{\pm}0.8ng/ml$ in primiparous bitches at the first day of vulval bleeding, $1.9{\pm}1.0$ and $3.3{\pm}2.7ng/ml$ at the first day of male acceptance, $7.0{\pm}4.0$ and $9.3{\pm}6.2ng/ml$ at the day of first mating, and $25.1{\pm}6.3$ and $22.8{\pm}10.3ng/ml$ at the last day of male acceptance, respectively. When Day 0 was timed from the day of parturition, plasma progesterone concentration at Day -62, Day -63 and Day -64 was $4.7{\pm}2.7ng/ml$, $3.5{\pm}2.2ng/ml$ and $1.7{\pm}0.9ng/ml$ in multiparous bitches, and $5.3{\pm}4.4ng/ml$, $3.2{\pm}3.7ng/ml$ and $2.0{\pm}1.9ng/ml$ in primiparous bitches, respectively. When Day 0 was timed from the day that plasma progesterone concentration was first increased above 3.0ng/ml after the first day of vulval bleeding, plasma progesterone concentration at Day 61 and Day 62 was $2.7{\pm}2.2ng/ml$ and $1.4{\pm}1.9ng/ml$ in multiparous bitches, and $3.4{\pm}5.2ng/ml$ and $3.7{\pm}5.6ng/ml$ in primiparous bitches, and $0.8{\pm}0.7ng/ml$ and $0.9{\pm}0.4ng/ml$ at Day 63, respectively. It was that bitches were mated when plasma progesterone concentraion was 1.9 to 14.2ng/ml and 3.5 to 20.0ng/ml in multiparous and primiparous bitches, which was between first day before ovulation and fourth day after ovulation. And pregnancy rate was 92% (23/25). From these data, ovulation was estimated to occur the day when plasma progesterone concentration was first increased above 3.0ng/ml after the first day of vulval bleeding. It was estimated that mating time was the day when plasma progesterone concentration was between 1.9 and 20.0ng/ml, and best time for mating was between 3.0 and 8.0ng/ml of plasma progesterone concentration.

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Effect of different parities on reproductive performance, birth intervals, and tail behavior in sows

  • Yang, Ka Young;Jeon, Jung Hwan;Kwon, Kyeong Seok;Choi, Hee Chul;Kim, Jong Bok;Lee, Jun Yeob
    • Journal of Animal Science and Technology
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    • 제61권3호
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    • pp.147-153
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    • 2019
  • A goal for swine farming is the improvement in the number of live-born and weaned piglets per sow. Hence, the effect of parities should consider the correlation between the component traits of reproductive performance, weaning, and duration. Sows were housed in farrowing pens (W 2.2 ${\times}$ D 1.8 ${\times}$ H 1.2 m) on a partially slatted plastic floor. Twenty sows used in this study were between the first and sixth parity in gilts (P1), parity 2-5 (P3), and parity 6-9 (P6). Data collection by parity was classified into three categories: (1) reproduction performance (gestation length, total number of piglets born, number of piglets live born, number of piglets stillborn, total piglet birth weight; (2) weaning traits (weaning period, number of piglets weaning, total piglets weaning weight); (3) duration traits (farrowing duration, placenta expulsion duration, time from last piglet to first placenta, average birth interval, and tail wagging behavior). Gestation length was higher in P6 than P1 and P3 of different parity sows. The maximum value in P1 and P3 was 117 days, but the median value in P6 was 117 days (p < 0.05). The total number of piglets born (p = 0.113), number of piglets live born (p = 0.118), number of still piglets born (p = 0.151), and total piglet birth weight (p = 0.117) were not affected by parity. The number of live piglets was higher than the other parities by an average of $15.6{\pm}2.1$ in P1. The duration of farrowing was the lowest at 22.2 min in P6, but the maximum value was 42.2 min more than other parities (p = 0.355). Weaning traits of sows also did not differ significantly (p > 0.05), but the weaning period from P1 was lower than that of the other parities (p = 0.170). The number of piglets weaned was 10 heads on average in P1, P3, and P6 (p < 0.05). However, the mean values of the total piglet weaning weight (p = 0.377) of P6 (62.0 10.4 kg) were higher than those of P1 (54.9 10.2 kg) and P3 (58.4 13.6 kg). The placenta expulsion duration was higher in P6 than that in P1 and P3 (p = 0.447). The time from the last piglet to first placenta was be lower in P3 than that of the other parities (p = 0.206). The average birth interval was higher in P3 than that of the other parities (p = 0.156). Tail wagging (count) behavior was higher in P6 than in the other parities (p = 0.065). The data showed that the reproduction performance, total piglets born, and weight were higher in the gilts group, and higher in the weaning trait than that in the P6 group. This study examined the relationship between reproductive performance, birth interval and tail motion according to sow parity. Regarding duration, farrowing duration was lower in P6 than that in the other parities, but placenta expulsion and tail wagging were higher in P6 than in the other parities. Therefore, it is possible that the results from these sows could be used as basic data for effective farm management.

제주산 씀뱅리 (Sebastiscus marmoratus)의 생식년주기와 체내자어 발달 (Annual Reproductive Cycle and Embryonic Development within the Maternal Body of the Marbled Rockfish, Sebastiscus marmoratus from the Cheju Island)

  • 배희찬;정상철;이정재;이영돈
    • 한국수산과학회지
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    • 제31권4호
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    • pp.489-499
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    • 1998
  • 1992년 7월부터 1996년 5월까지 제주도 연안에서 어획된 쏨뱅이, Sebastiscus marmoratus 1,035개체를 대상으로 생식소 발달과정. 생식주기 및 체내자어 발달과정을 조사하였다. 생식소중량지수 (GSI)에 있어 암컷의 GSI값은 10월부터 3월에 최대값에 이른 후 11월에서 4월에 감소하였고. 수컷은 9월에 최대에 이른 후 (암컷보다 1$\~$3개월 전에) 10월부터 12월까지 감소하였다. 생식년주기는 암컷은 성장기 (6$\~$9월). 성숙기 (9$\~$2월). 완숙기 및 교미기 (10$\~$3월). 임신 및 산출기 (11$\~$4월), 퇴화 및 휴지기 (12$\~$5월)의 나타났고. 수컷은 성장기 (4$\~$7월). 성숙기 (8$\~$11월), 완숙기 및 교미기 (9$\~$12월), 퇴화 및 휴지기 (11$\~$3월)로 구분된다. 난경과 체내자어 체장조성은 비동시성을 나타내었고, 체내자어산출은 11월에서 4월 동안 1회 또는 2회 일어났다. 산출자어의 평균크기는 3.5mm였다. 포란수와 체내자어수는 최소 체장 15cm급에서는 평균 58,377개이고, 전장과 체중이 증가함에 따라 포란수와 체내자어수는 증가되는 현상을 나타내었다.

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유기수은 노출로 인한 흰쥐 태자골격성장 지연에 대한 마늘의 보호효과 (Protective Effects of Korean Garlic Juice against the Toxicity of Methyl Mercuric Chloride (MMC) in Relation to Fetal Ossification in Pregnant Fischer-344 Rats)

  • 이진헌;박경렬;김대선
    • 한국환경보건학회지
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    • 제34권2호
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    • pp.161-169
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    • 2008
  • This study evaluates the protective effects of Korean garlic juice against the toxicity of methyl mercuric chloride (MMC) in relation to fetal ossification in pregnant Fischer 344 rats. This study has as its basis, both theory and data that neutral amino acids in garlic juice have protective effects against mercury poisoning. Pregnant rats were dosed in various combination with 20 mg MMC/kg body wt. and 0.5 or 1.0 garlic juice/kg body wt. on the 7th day of gestation. Fetuses were extracted from the dams on 20th day of gestation, and the fetal bones were stained and measured. The results obtained are as follows: 1. Fetal body weights, body lengths, and head length were significantly decreased by as much as 23.5%, 21.3%, 15.5% respectively in 20 mg/wt kg methyl mercuric chloride groups (p<0.05). But in the garlic treated groups, they were almost similar to the controls. 2. The ossification centers were significantly decreased by as much as 35.1% in pelvic phalanges, 53.5% in pectoral phalanges, 74.1% in ternebrae, 76.2% in tail in 20 mg/wt kg methyl mercuric chloride groups (p<0.05). But in the garlic treated groups, they were significantly increased by as much as $81.2{\sim}88.7%$ and $94.8{\sim}98.9%$ of controls. 3. The ossified pectoral girdles were significantly decreased by as much as 66.6% in clavicle, and in other areas $74.2{\sim}87.4%$ in the 20 mg/wt kg methyl mercuric chloride groups (p<0.05). But in the garlic treated groups, they were significantly increased by as much as $81.2{\sim}88.7%$ and $94.8{\sim}98.9%$ of the controls. 4. The ossified pelvic girdles were significantly decreased by as much as 57.1% and 56.1% in two ischium, $67.2{\sim}81.7%$ in metacarpals in the 20 mg/wt kg methyl mercuric chloride groups (p<0.05). But in the garlic treated groups, they were significantly increased by as much as $67.0{\sim}85.6%$ and $90.1{\sim}98.7%$ of the controls. 5. The ossified terenebrae were unchanged or significantly decreased; 0.0% in 5th, 54.1% in 1st, 83.9% in 2nd, 75.0% in 3rd, 72.7% in 4th, 79.8% in 6th of 20 mg/wt kg methyl mercuric chloride groups (p<0.05). But in the garlic treated groups, they were significantly increased by as much as $29.5{\sim}55.1%$ and $54.5{\sim}84.0%$ of the controls. 6. The ossified ribs were significantly decreased by as much as $8.3{\sim}18.0%$ in 20 mg/wt kg methyl mercuric chloride groups (p<0.05). But in the garlic treated groups, they were significantly increased by as much as $87.1{\sim}93.5%$ and $96.3{\sim}99.7%$ of the controls. In conclusion, Korean garlic juice significantly protected against the toxicity of MMC in relation to the fetal ossification in pregnant rats.

재태연령 26주 이상 35주 이하 미숙아의 신체계측치의 분석; 1960년대 측정치와의 비교 (Analysis of anthropometric data for premature infants of 26 to 35 weeks of gestation; comparison with the data of 1960's)

  • 엄지아;정희진;허재원;손상희
    • Clinical and Experimental Pediatrics
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    • 제50권6호
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    • pp.543-548
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    • 2007
  • 목 적 : 현재 우리나라에서 가장 많이 사용되고 있는 재태 연령에 따른 출생시 체중, 신장, 두위의 정상 신체 계측치의 기준은 Lubchenco 등에 의해 1960년대에 발표된 것으로 2000년대에 출생한 우리나라 미숙아들에게는 맞지 않는 부분이 많으리라 예상되어 이를 2000년도 이후로 출생한 본원의 미숙아들의 출생시 신체 계측 자료와 비교 분석해 보고자 본 연구를 시행하였다. 방 법 : 2000년 1월부터 2006년 8월까지 본원에서 출생한 재태 연령 26주에서 35주까지의 미숙아 1,010명을 대상으로 하였으며 이들의 재태 연령에 따른 출생시 체중, 신장, 두위의 신체 계측치의 백분위수를 Lubchenco 등의 기준과 비교 분석하였다. 결 과 : 본 연구에서 저자들이 측정한 재태 연령별 출생 체중은 90백분위수가 조사한 전체 재태 연령에 걸쳐 Lubchenco 기준보다 현저하게 작았으며 특히 30주 미만인 경우 Lubchenco 기준의 75백분위수 정도에 해당하였고 10백분위수는 전체 조사 재태 연령에서 Lubchenco 기준보다 크게 나타났다. 저자들이 측정한 재태 연령별 출생 신장과 두위는 90백분위수가 조사한 전체 재태 연령에 걸쳐 Lubchenco 기준보다 현저하게 작아서 Lubchenco 기준의 75백분위수 정도에 해당하였고 10백분위수는 전체 조사 재태 연령에서 Lubchenco 기준보다 크게 나타났다. 결 론 : 40년 전에 만들어진 Lubchenco 기준을 현재의 우리나라 미숙아들에게 적용하는 것은 무리가 있으며 이로 인해 자궁 내 발육 지연 또는 부당 경량아나 부당 중량아들이 과소평가될 위험이 있다. 이러한 과소평가로 인해 진단과 치료가 늦어져서 사망률과 유병율이 높아질 수 있음을 감안해 볼 때 저자들의 미숙아들의 신체 계측치 기준이 미숙아의 사망률과 유병율 감소에 도움이 될 수 있을 것으로 기대된다.

Genetic parameters of calving ease using sire-maternal grandsire model in Korean Holsteins

  • Alam, Mahboob;Dang, Chang Gwon;Choi, Tae Jeong;Choy, Yun Ho;Lee, Jae Gu;Cho, Kwang Hyeon
    • Asian-Australasian Journal of Animal Sciences
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    • 제30권9호
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    • pp.1225-1233
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    • 2017
  • Objective: Calving ease (CE) is a complex reproductive trait of economic importance in dairy cattle. This study was aimed to investigate the genetic merits of CE for Holsteins in Korea. Methods: A total of 297,614 field records of CE, from 2000 to 2015, from first parity Holstein heifers were recorded initially. After necessary data pruning such as age at first calving (18 to 42 mo), gestation length, and presence of sire information, final datasets for CE consisted of 147,526 and 132,080 records for service sire calving ease (SCE) and daughter calving ease (DCE) evaluations, respectively. The CE categories were ordered and scores ranged from CE1 to CE5 (CE1, easy; CE2, slight assistance; CE3, moderate assistance; CE4, difficult calving; CE5, extreme difficulty calving). A linear transformation of CE score was obtained on each category using Snell procedure, and a scaling factor was applied to attain the spread between 0 (CE5) and 100% (CE1). A sire-maternal grandsire model analysis was performed using ASREML 3.0 software package. Results: The estimated direct heritability ($h^2$) from SCE and DCE evaluations were $0.11{\pm}0.01$ and $0.08{\pm}0.01$, respectively. Maternal $h^2$ estimates were $0.05{\pm}0.02$ and $0.04{\pm}0.01$ from SCE and DCE approaches, respectively. Estimates of genetic correlations between direct and maternal genetic components were $-0.68{\pm}0.09$ (SCE) and $-0.71{\pm}0.09$ (DCE). The average direct genetic effect increased over time, whereas average maternal effect was low and consistent. The estimated direct predicted transmitting ability (PTA) was desirable and increasing over time, but the maternal PTA was undesirable and decreasing. Conclusion: The evidence on sufficient genetic variances in this study could reflect a possible selection improvement over time regarding ease of calving. It is expected that the estimated genetic parameters could be a valuable resource to formulate sire selection and breeding plans which would be directed towards the reduction of calving difficulty in Korean Holsteins.