• Asian-Australasian Journal of Animal Sciences
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• 제32권4호
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• pp.519-526
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• 2019

Objective: We determined the risk factors limiting first service conception (FSC) rate in dairy cows and their economic impact. Methods: Data were collected from 790 lactations regarding cow parity, peri- and postpartum disorders, body condition score (BCS), reproductive performance, and expenses associated with reproductive management (treatment, culling, and others). Initially, we identified the risk factors limiting FSC rate in dairy cows. Various biological and environmental factors, such as herd, cow parity, BCS at 1 month postpartum and first artificial insemination (AI), resumption of cyclicity within 1 month of calving, year, AI season, insemination at detected estrus or timed AI, peri- and postpartum disorders, and calving to first AI interval, were evaluated. Next, we evaluated the economic impact of the success or failure of FSC by comparing the expense associated with reproductive management until conception between cows that did or did not conceive at their first service. Results: Cows with BCS <3.0 had a lower probability of conceiving at first insemination (odds ratio [OR] = 0.64, p<0.05) than cows with $BCS{\geq}3.0$. Cows inseminated during summer were less likely to conceive (OR = 0.44, p<0.001) than cows inseminated during spring. Cows with peri- or postpartum disorders were less likely to conceive (OR = 0.55, p<0.001) than cows without disorders. Survival curves generated using MedCalc showed an 81 day extension in the mean interval between calving and conception in cows that failed to conceive over those that did conceive at first insemination. Cows failing conceive required additional expenditure on reproductive treatment ($55.40) and other management ($567.00) than cows that conceived at first insemination. Conclusion: Lower BCS, hot weather at first insemination, and peri- and postpartum disorders are risk factors limiting FSC, which result in an economic loss of $622.40 per dairy cow.

• Asian-Australasian Journal of Animal Sciences
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• 제14권6호
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• pp.747-753
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• 2001

In this study, the Italian milk recorded buffalo population from 1974 to 1996 was analysed with the purpose to estimate genetic and environmental variability and provide genetic parameters for the most important economic traits. High variability between herds was evident due to the poor knowledge of feeding requirements and husbandry technology in this species compared to cattle. Age at first calving was reduced by 57 days during the considered years following efforts made in better feeding and management from 1990; on the contrary, calving interval has increased by 17 days as a consequence of forcing buffaloes to calve in spring, in order to have the peak milk yield when milk is much better paid. Average milk yield increased by 1853 kg during these years, while lactation duration was reduced by 30 days. Season of calving has no effect on all traits. Calving order has a positive effect on milk yield especially because older cows produce more milk in shorter lactations. Heritability for the age at first calving and calving interval was 0.26 and 0.05 respectively. Heritability of productive traits, milk yield and duration of the lactation was 0.19 and 0.13 respectively, with repeatabilities of 0.40 and 0.26. Genetic trend for milk yield was 2.1 kg milk/year for the bulls and 1 kg for all population. The high genetic variability of milk production as well as duration of the lactation, indicates that there are good opportunities for genetic improvement when including these traits in a selection scheme. The low genetic trend registered over 15 years of recording activity can be explained by the fact that neither progeny testing was performed or selection schemes were implemented, due to the difficulties to use artificial insemination in buffalo.

• 한국임상수의학회지
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• 제36권1호
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• pp.68-73
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• 2019

We determined the risk factors for displacement of the abomasum (DA), and the relationships between DA and postpartum disorders, milk yield, and reproductive performance in dairy cows. Initially, we identified the risk factors for DA using data regarding cow health and calving season from 2,208 lactations. Then, we compared the incidence of postpartum disorders, culling, death, and reproductive performance between cows with DA and their control herdmates (each n = 57). In addition, serum metabolites concentrations and milk yield were compared between cows with DA and controls (each n = 33). Ketosis (odds ratio [OR] = 9.27, p < 0.0001) and twin calves (p = 0.06) increased the risk of DA. Cows with a parity of three had a higher risk (OR = 5.23, p < 0.01) of DA than primiparous cows. Serum total cholesterol concentration was lower but non-esterified fatty acid, ${\beta}-hydroxybutyrate$, and alanine aminotransferase concentrations were higher after calving in cows with DA than in controls (p < 0.05). The removal rate from the herd by 2 months after calving was higher (p < 0.05) but milk yield 1 and 2 months after calving (p < 0.01) and the rate of first insemination by 150 days postpartum were lower (hazard ratio = 0.49, p < 0.05) in cows with DA than controls. In conclusion, higher parity, twin calves, and ketosis are risk factors for DA in dairy cows, which is associated with a higher removal rate from the herd, lower milk yield, a longer calving to first insemination interval, and unfavorable levels of metabolites related to energy and liver function.

• 한국임상수의학회지
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• 제20권3호
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• pp.369-375
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• 2003

The ultrasonography was performed in 77,924 subestrous dairy cows from 680 dairy farms at 57 districts. The cows were examined for confirmation of resumption of ovaries and uterus after 30 days postpartum, for early pregnancy diagnosis after 30 days post-insemination, confirmation of pregnancy at 8 month post-insemination, and for diagnosis of reproductive dysfunctions, respectively. The results of reproductive examination by ultrasonography in 77,924 dairy cows were ovarian disorders 35,452 (46.8%), uterine disorders 10,721 (13.8%), pregnancy and pregnant failure 24,044 (30.8%), adhesion of reproductive tracts 167 (0.2%), freematins 13 (0.01%) and others 6,527 (8.4%) cows, respectively. The 13,732 (49.6%) cows out of 27,694 cows were treated for silent heat or error of estrus detection, 3,473 (12.5%) cows for follicular cysts, 815 (3.0%) cows for luteal cysts, 606 (2.2%) cows for inactive ovaries, 4 (0.01%) cows for granulosa cell tumors, and 6,455 (23.3%) cows for endometritis, respectively. The indices of reproductive efficiencies before (2001-08-10) and after (2003-07-20) periodical examination of reproductive status were as follows; the mean intercalving interval were shortened from 471 days to 383 days, the mean interval calving to conception were shortened from 187 days to 99 days, the mean interval calving to first service were shortened from 105 days to 67 days, the mean cows showing heat by 60 days postpartum were increased from 33% to 89%, the mean conception rate to first service were increased from 43% to 68%, and the mean service per conception were shortened from 2.6 times to 1.8 times, respectively. These results suggest that periodical examination of reproductive status would be useful for the improvement of the reproductive performance in dairy cows.

• 한국임상수의학회지
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• 제1권1호
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• pp.25-31
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• 1984

The effects of progesterone releasing intravaginal device (PRID) on the fertility levels in dairy cows were studied in 2 experiments. In experiment I, 70 lactating cows at 45 days postpartum were allotted to 3 groups and the treatments imposed were either： 1: Untreated control, 2: PRID with a capsule containing long of oestradiol benzoate (ODB) attached, inserted for 12 days, 3: PRID inserted for 12 days with long of prostaglandin F$\_$2${\alpha}$/ administration 24 h before PRID removal. Treated cows were inseminated 56 h after PRID removal and at an observed oestrus during the subsequent 48-day period. The control group was inseminated at an observed oestrus during this 60-day period. In experiment II, 60 ovarian disorder cows were divided into 5 groups and PRID+ODB inserted for 12 days. 1: atrophied ovary, 2: smooth ovary, 3: persistent corpus luteum, 4: follicular cyst, 5: luteal cyst. Treated cows were inseminated 56 h after PRID removal and at an observed oestrus over a period from the first insemination to 46 days. The results obtained were as follows: 1. The device produced a vaginal discharge in some animals. In experimenet I : 2. For treatments 2 and 3, respectively, conception rates to the fixed time insemination were 45% and 52%. 3. The conception rates of cows inseminated to the fixed time insemination and at an observed oestrus during a 60-day period were 65%, 86% and 91% for control, treatment 2 and 3, respectively. 4. Mean interval from calving to conception and inseminations per conception were 133, 91 and 86 days and 2.4, 2.1 and 1.9 for control, treatments 2 and 3, respectively. In experiment II； 5. The conception rates to the fixed time insemination for each group 20, 50, 70, 20 and 50%, respectively. 6. The total conception rates for the 48 days period of each group were 60, 70, 100, 60 and 90%, respectively. 7. The inseminations per conception of each group were 2.8, 2.1, 1.4, 2.7 and 1.9, respectively.

• 대한수의학회지
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• 제27권1호
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• pp.137-140
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• 1987

Information on certain reproductive traits were obtained from field material. The data for this study were taken from 1,111 breeding records of 273 cows and 193 heifers at Koheung, Chonnam, during the period 1979 to 1984. The cattle were bred by artificial insemination; only one or two cattle were reared by one farmer. The heifers were first bred at 551.75 days after they were born; they were pregnant at 569.06 days after birth. The average estrous cycle length was 21 days; the average number of inseminations per conception was 1.56. The non-return rate for first inseminations for cows and heifers was 62.5% and 59.6%, respectively. The gestation length was 285.79 days. Of 1,111 viable calved born 582 were male, giving a sex ratio of 100:110. The average length between calving and first insemination was 88.9 days; average calving interval was 397.69 days.

• 한국임상수의학회지
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• 제33권2호
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• pp.93-96
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• 2016

This retrospective study evaluated the effect of age at first calving on the productive and reproductive performance in Holstein dairy cattle. Data were collected on 2,297 lactations from 19 dairy farms, including dates of birth, insemination, pregnancy, calving, and lactation and milk production (305-day milk yield at first lactation and lifetime milk yield). Lactation data were grouped based on age at first calving into the early (< 24 months, n = 414), moderate (24 ${\leq}$ and ${\leq}$ 28 months, n = 1,268), and late (> 28 months, n = 615) groups. The 305-day milk yield at first lactation was higher (p < 0.005) in the late group (8,461.9 kg) than in the early (8,130.8 kg) and moderate (8,261.9 kg) groups. Lifetime days in milk were shorter (p < 0.01) in the early group (1,045.7) than in the moderate (1,143.1) and late (1,110.7) groups, whereas the lifetime milk yield was higher (p < 0.05) in the moderate group (34,171.8 kg) than in the early group (31,791.6 kg). The second calving interval (days) differed (p < 0.0001) between the early (416.9), moderate (438.9), and late (455.3) groups. The culling rate at the first and second lactations tended to be higher (p = 0.08) in the early group (31.2%) than in the moderate group (26.0%), whereas it was intermediate in the late group (29.3%). In conclusion, dairy heifers aged 24-28 months at first calving showed a higher productive performance through an increased lifetime milk yield and a decreased culling rate.

• 농업과학연구
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• 제47권3호
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• pp.667-672
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• 2020

It is well known that intensive selection caused a decline in reproductive performance in dairy cattle. Interestingly, the reproductive performances including fertility and calving interval of Korean native beef cattle have declined in the last 20 years, suggesting that a breeding program focusing on carcass weight and intramuscular fat may affect the reproductive physiology in Korean native beef cattle, too. In this study, we analyzed the calving interval (CI) and selection index (SI) based on genome-wide association studies (GWAS) of Hanwoo cows for seven years (2013 - 2019). Multiparous cows (4.5 ± 0.11) were analyzed, which were bred by artificial insemination (AI). We first examined the distribution of the AIs and calving dates. About 40% of the AIs were carried out in May to June and October to December; subsequently, calving was observed from March to April and August to October, respectively, indicating the cows were seasonally bred. No correlation between CI and SI was found (y = 0.0459x - 17.64; R² = 0.0356), but the ratio of cows with a positive SI was higher in the longer CI group compared to the shorter group, suggesting that the selection for meat quality and quantity may affect the reproductive performances. In addition, the average value of SI was - 3.42 in the CI < 400 while + 5.79 in the CI > 400 although the values were not statistically significant. However, our results suggest that reproductive indices such as fertility and CI should be considered for sustainability in the Hanwoo breeding selection program.

• 한국가축번식학회지
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• 제10권1호
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• pp.58-65
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• 1986

The results from a survery on the reproduction of a, pp.oximately 500 dairy cows raised in four different farming areas including Cheju city, Jochun, Hallim and Sung-up are summarized as follows; 1. At the occurrence of first estrus, the average age of the heifers was 15.1 months (330 Kg/B.W.), and at first conception 18.0 months (354Kg/B.W.). There was no regional differences. 2. The average interval of the estrous cycle was 20.4 days. And the repetition of esturs after unsuccessful insemination occurred on an average of 1.6 times, especially 2.0 times in the herds of the Jochun district. 3. The ages at the first calving were similar to the data recorded for the domestic mainland's herds at 27.1 months. But some regional differences were recognized within the four districts: i.e. 28.6 (Cheju city), 27.4(Jochun), 27.1(Hallim) and 25.3 months (Sung-up). There was no significant differences in sex ratio of newborns at 50.4%(♂) and 49.6%(♀). 4. The intervals of esturs recurrence and the following conception after calving were 80.0 and 95.8 days respectively. In the followsing conception intervals after cavling, 90.6-97.4 days were average for the herds of Cheju city and Jochun districts, 62.4-69.7 days for those of Hallim and Sung-up districts. 5. The average gestation period was 279.8 days, and was almost identical in the four districts. 6. The calving intervals was 377.7 days in average, and it was shorter than the data recorded for the domestic mainland's herds. Also it was reduce gradually according to the calving frequency.

• 한국임상수의학회지
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• 제30권6호
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• pp.435-441
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• 2013

본 연구는 젖소에서 분만 후 첫 수정 간격 및 임신 간격이 이후의 번식능력에 미치는 영향에 대하여 조사하였다. 첫 번째 분석에서는, 705두의 젖소 자료를 첫 수정 간격에 따라 짧은 간격(30-60일, n=217), 중간 간격(61-90일, n=309) 및 긴 간격(91-150일, n=179) 군으로 구분하였다. 자궁내막염의 발생은 짧은 간격 및 중간 간격 군에 비해 긴 간격 군에서 증가되었다(p<0.05). 첫 수정 간격이 증가함에 난소낭종의 발생은 증가한(p<0.05) 반면, 분만 후 5 개월 간의 BCS는 반대로 낮았다(p<0.01). 분만 후 365일까지의 임신율은 중간 간격 군에 비하여 긴 간격 군에서는 낮았으나(hazard ratio[HR]=0.70, p<0.0001), 짧은 간격 군에서는 높았다(HR=1.41, p<0.0001). 두 번째 분석에서는, 436두의 젖소 자료를 임신 간격(공태 기간)에 따라 짧은 간격(30-90일, n=154), 중간 간격(91-180일, n=183) 및 긴 간격(181-360일, n=99) 군으로 구분하였다. 후산정체 발생율은 중간 간격 군에 비해 긴 간격 군에서 높았으나 (p<0.05), 난소낭종의 발생은 짧은 간격 군에 비해 중간 간격 및 긴 간격 군에서 증가하는 경향이 있었다(p=0.08). BCS는 분만 후 1개월에 중간 간격 및 긴 간격 군에 비해 짧은 간격 군에서 낮았다(p<0.05). 산유량은 분만 후 2개월에서 5개월까지 짧은 간격 군에 비해 중간 간격 군에서 증가하였다(p<0.05). 분만 후 150일까지 첫 수정율은 짧은 간격 군에 비해 긴 간격 군이 낮았다(HR=0.73, p<0.02). 분만 후 365일까지의 임신율은 중간 간격 군에 비하여 긴 간격 군에서는 낮았으나(HR=0.64, p<0.0001), 짧은 간격 군과 중간 간격 군에서는 차이가 없었다(p > 0.05). 더욱이, 도태율은 짧은 간격 군에 비해 긴 간격 군에서 증가하였다(p<0.05). 결론적으로, 젖소에서 첫 수정 간격 및 임신 간격의 연장은 이후 번식능력의 감소를 초래하였으며, 이것은 산후 질병의 증가, BCS 감소 및 많은 산유량에 기인하였다.