• Korean Journal of Animal Reproduction
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• v.25 no.3
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• pp.227-230
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• 2001

To know and apply the factors affecting calf's gender may increase our competitiveness of Hanwoo industry. Thus, this study was carried out to analyse the effect of expected factors on calf's gender and to make an alternative idea for desired calf's gender. Gender of calves born by AI was not affected by AI year and cow parity, but significantly affected by sire and farm. Therefore, to obtain calves' gender that we want, both selecting optimum sire for AI and providing optimum feeding environment for cow should be required.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.6
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• pp.895-899
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• 2002

Lysozyme activity in buffalo milk in relation to the period of lactation, parity of animal, weather conditions and udder infections was studied. Effect of storage and heat processing of milk on lysozyme activity was determined. Lysozyme activity was higher in buffalo milk than in cow milk. Buffalo colostrum showed lysozyme activity 5 times of that in mature milk. Lysozyme activity in buffalo milk was not influenced by the parity of animal and the stage of lactation, however, it increased during extreme whether conditions (winter and summer). Lysozyme in both cow and buffalo milk exhibited maximum activity at pH 7.4. Buffalo milk lysozyme was fully stable while the cow milk lysozyme was partly inactivated by pasteurization (low temperature-long time as well as high temperature-short time treatments). Lysozyme in buffalo milk was more stable than in cow milk during storage and heat treatment. A 10 to 50-fold increase in milk lysozyme activity was observed in mastitic cows. An assay of lysozyme activity in milk can be used to diagnose mastitis in cattle but not in buffaloes. Some buffaloes exhibited 1000 fold greater lysozyme activity and moderately raised somatic cell count in milk, but there was no sign of mastitis in these animals. A possible role of milk lysozyme in prevention of mastitis in buffaloes is discussed.

• Korean Journal of Animal Reproduction
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• v.25 no.3
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• pp.231-235
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• 2001

Gestation duration of cow is an important economical trait. Shortening the gestation duration decreases the production cost and increases the competitiveness of Hanwoo industry. Thus, this study was carried out to analyse the effect of expected factors on gestation duration and make an alternative idea for reduced gestation duration. Gestation duration was not affected by cow-parity, but significantly affected by farm, Al year and sire. Therefore, reducing the gestation duration of Hanwoo may require both providing optimum feeding environment and nutrition management for cow and selecting optimum sire for AI.

• Journal of Veterinary Clinics
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• v.33 no.6
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• pp.351-355
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• 2016

This study was conducted to investigate reasons for culling of Chungcheong dairy herds and to investigate the relationships between cow parity, interval from calving to culling, or season and culling reasons. Lactation data from 826 cows on 9 dairy farms from 2013 to 2015, including reasons for culling, dates of birth, last calving, and culling, were analyzed. The overall culling rate was 29.8% (246/826), with mammary problems (23.2%) being the most prevalent reason for culling, followed by infertility (14.2%) and downer cow syndrome (11.0%). The culling rate varied among farms (18.8-43.1%, p < 0.05), but was greater in parity $4{\leq}(40.7%)$ than parities 1, 2, or 3 (17.9-23.6%), whereas the rate was less frequent during mid lactation (21.1%) than in early (36.2%) or late (42.7%) lactation. Moreover, the culling rate was greater during summer (35.8%) than other seasons (20.3-23.2%). Mammary problems, downer cow syndrome, and metabolic disorders were the more common reasons for culling during early lactation, whereas infertility was predominant during late lactation. Our data show that the culling rate in Chungcheong dairy herds was associated with cow parity, interval from calving to culling, and season, with the main reasons for the removal of cows from dairy herds being mammary problems, infertility, and downer cow syndrome.

• Food Science of Animal Resources
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• v.20 no.2
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• pp.87-92
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• 2000

This study was performed to provide scientific information for consumers and to increase the quality and consumption of Sullungtang prepared with bone from Hanwoo. The physico-chemical, sensory, nutritional properties of Sullungtang by different parity were investigated. The extracting extents of blood were significantly higher for heifer among Hanwoo cows with different parity(none, the second or the fourth) and for back bones among different bone portions (round, hind shank, arm, fore shank or back bone) (p〈0.05). For Sullungtang extracted from bones of heifer was higher in collagen contents than those extracted from cows with the second or the fourth parity. Sullungtang extracted from bones of heifer and cows with the second parity had significantly higher contents of condroitin and viscosity than those of cows with the fourth parity, however there was no significant difference between heifer and cows with the second parity. In color, L values were significantly high, and a and b values were significantly low for Sullungtang extracted from bones of heifer when compared to those extracted from the other cows with the second parity. The contents of total nitrogen, sodium, or calcium were higher for Sullungtang extracted from heifer than those from the cows with the second or the fourth parity. In amino acid compositions, the percentages of glycine were highest and proline and glutamic acid were followed fro all Sullungtang samples from Hanwoo. The results showed that the overall quality of Sullungtang significantly decreased as the parity increased for Hanwoo cows. The Sullungtang extracted from bones of heifer had the best sensory scores as well as nutritional quality when compared to those extracted from the cows with parity. Therefore, the labeling and price for cow bones should be differently evaluated by their parity and age in marketing system.

• Korean Journal of Animal Reproduction
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• v.23 no.3
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• pp.183-189
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• 1999

A study was conducted to estimate the effects of parity of dam, sex, year and season of birth on gestation length and birth weight in Korean native and Yanbian yellow cows. A total of 1,206 reproduction records (587 Korean native cows, 619 Yanbian yellow cows) were collected from Daekwamyeong Branch Institute, National Livestock Research Institute in Korea and Yanbian region in China from 1995 to 1998. The least square means for gestation length and birth weight of Korean native cows and Yanbian yellow cows were 287.3$\pm$0.60 and 282.3$\pm$0.80 days, 24.9$\pm$0.25 and 25.2$\pm$0.24kg, respectively. Gestation length and birth weight were increased significantly as parity of dam progressed in Korean native cow(p＜0.01), but were not significant in Yanbian yellow cow. Birth weight of male calf was heavier than that of female calf in Korean native cow and Yanbian yellow cow(p＜0.01). Gestation length of Korean native cow born male calf was longer than that of Korean native cow born female calf(p＜0.01), but was not significant in Yanbian yellow cow. Effect of birth year on birth weight was significant in Korean native cow and Yanbian yellow cow(p＜0.01), but effect of birth year on gestation length was not significant. Birth weight of spring-born calf was the heaviest and that of fall-born calf was the smallest in Korean native cow and Yanbian yellow cow(p＜0.01).

• Journal of Embryo Transfer
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• v.31 no.3
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• pp.273-279
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• 2016

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 $R^2=0.9157$). Interestingly, we observed that parities for life time can be affected by birth weight. Calves with 23 kg at birth showed highest parities, $3.4{\pm}2.0$ 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.

• Korean Journal of Organic Agriculture
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• v.31 no.4
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• pp.327-341
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• 2023

The Ministry of Agriculture, Food and Rural Affairs, Hanwoo Association and Nonghyup have discussed proactive reduction measures for cows in response to concerns about an oversupply of hanwoo to ensure supply stability. This study aims to empirically analyze whether the cow fattening support program is being implemented in line with its objectives. Based on the analysis of beef traceability data, the slaughter age of participating cows was reduced by 7.6 to 14.7 months compared to non-participating cows. And heifer was reduced 1.5 months in their slaughter age. In case of parity, participating cows showed a reduction of 1.4 compared to non-participating cows. Through the SUR model, an analysis was conducted to examine the effect of the cow fattening support program on the suppression of calf production numbers. The analysis results showed that the calf production numbers are positively influenced by the number of fertile cow and the quantity of semen sales. Furthermore, it is estimated that calf production decreased as the fat index increased, and during the period when the cow fattening support program was implemented, an average monthly suppression of 3,558 calves was observed.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.4
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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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• v.17 no.12
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• pp.1689-1694
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• 2004

This study was conducted to develop a novel adjustment factors for 305 days using 138,103 lactation records and 1,770,764 daily records, which were based on environmental circumstances such as herd year, season, age at calving, dry period and lactating stages. The present study showed that the change of persistency of cows at the first parity from total lactacting characteristics was slowly processed, while it was rapidly changed in cows at the second parity stage. Particularly, there was an outstanding difference between the first and second parity cows. Milk yield and composition increased as the age at calving was increased. In addition, milk yield and composition were higher at the first parity on fall compared with others, and those were higher at the more than second parity on fall and winter compared with other parity stages and seasons. The cow of dry group was included into lactating records of more than second parity stage. The data indicated that optimal results arose from 45-70 days of dry period. Milk yield was decreased when dry period was longer or shorter than 45-70 days. The lactating days were divided into 17, 28 and 38 stages to compare the multiplicative correction factors. The factor was effective at 28 stages on the first parity. The total correlation coefficients were 0.93832, 0.95058 and 0.95076 at the present correction factor, 17 stage and 28 stage, respectively. At second parity, the factor was higher in dry group 1 and 3 at 17 stage, and it was higher in dry group 2 at 28 stage compared with others. Therefore, the present study showed that the percent squared bias (PSB), which was calculated from the novel correction factor, was better than previously used correction factors. Also, the present study indicated that the bias of the novel correction factor was improved, and this factor could be more accurate compared with others.