• Asian-Australasian Journal of Animal Sciences
• /
• v.31 no.7
• /
• pp.951-960
• /
• 2018

Hanwoo cattle are an important food source in Korea and their supply can have a major impact on meat availability for Korean consumers. The Hanwoo population was 1.8 million head in 2005 and gradually increased to 2.6 million in 2015. Per capita beef consumption has also increased, to 11.6 kg per year in 2015, and is expected to continue to increase. Because intramuscular fat percentage is a critical contributor to meat quality, Hanwoo cattle are fed a high-energy corn-based diet for long fattening periods. Long fed diet causes significant alterations in fat percentage in the loin muscle and other areas of the carcass. However, these long feeding periods increase feeding costs and beef prices. Recently, there has been increased Korean consumer demand for lean beef which has less fat, but is tender and priced more reasonably. These consumer demands on the Korean beef industry are driving differing beef production systems and also changes to the beef grading methodology. Korean government has made a significant investment to select bulls with favorable production traits using progeny testing. Progeny tested bull semen has been disseminated to all Hanwoo farmers. A beef traceability system has been employed for all cattle breeds in Korea since 2009. Hanwoo cattle are ear-marked with a 12-digit identification number from birth to slaughter. This number allows traceability of the management history of individual cattle, and also provides information to consumers. Traceability including management information such as herd, farm, year of birth, and carcass data can determine estimated breeding values of Hanwoo. For a sustainable Hanwoo industry, research scientists in Korea have attempted to develop feeds for efficient fattening periods and precision feeding systems based on genetic information for Hanwoo cattle. These initiatives aim to Korean consumer demands for beef and provide more precision management in beef production in Korea.

• Journal of Animal Science and Technology
• /
• v.48 no.6
• /
• pp.759-766
• /
• 2006

This study was conducted to investigate the genetic correlations among the traits used to select young bulls and proven bulls in Hanwoo Performance and Progeny Test Program in Korea. For the estimation of heritabilities and correlations among the growth traits of bulls and carcass traits of progeny steers, 2,532 records of performance tested bull calves and 1,819 records of progeny tested steers were collected from Livestock Improvement Main Center (LIMC), National Agricultural Cooperative Federation (NACF). Fixed effects of mixed model for each traits were selected by using stepwise regression analysis and prior values of variance components were estimated by MTDFREML. The prior values of variance components were estimated with pairwise 2 traits model followed by single trait analysis. The estimated heritability of backfat thickness(BF), dressing percentage(DP), loin-eye muscle area(LMA), marbling score(MS) and weight at 12 months(WT12) was 0.51, 0.32, 0.27, 0.33, 0.50 and 0.26, respectively. Genetic correlation of WT12 of bull calves with backfat thickness, carcass weight and loin-eye muscle area of steers was positive correlation as 0.05, 0.35 and 0.21, respectively. However genetic correlation of WT12 with DP and MS showed negative correlation as 󰠏0.09 and 󰠏0.27, respectively and these negative genetic correlations implies that bulls that may be superior in carcass traits can be lost at the first step of selection and current selection method should be modified to solve this problem.

• Asian-Australasian Journal of Animal Sciences
• /
• v.32 no.2
• /
• pp.159-169
• /
• 2019

Objective: Models for genomic selection assume that the reference population is an unselected population. However, in practice, genotyped individuals, such as progeny-tested bulls, are highly selected, and the reference population is created after preselection. In dairy cattle, the intensity of selection is higher in males than in females, suggesting that cows can be added to the reference population with less bias and loss of accuracy. The objective is to develop formulas applied to any genomic prediction studies or practice with preselected animals as reference population. Methods: We developed formulas for calculating the reliability and bias of genomically enhanced breeding values (GEBV) in the reference population where individuals are preselected on estimated breeding values. Based on the formulas presented, deterministic simulation was conducted by varying heritability, preselection percentage, and the reference population size. Results: The number of bulls equal to a cow regarding the reliability of GEBV was expressed through a simple formula for the reference population consisting of preselected animals. The bull population was vastly superior to the cow population regarding the reliability of GEBV for low-heritability traits. However, the superiority of reliability from the bull reference population over the cow population decreased as heritability increased. Bias was greater for bulls than cows. Bias and reduction in reliability of GEBV due to preselection was alleviated by expanding reference population. Conclusion: Cows are easier in expanding reference population size compared with bulls and alleviate bias and reduction in reliability of GEBV of bulls which are highly preselected than cows by expanding the cow reference population.

• Journal of Animal Science and Technology
• /
• v.52 no.1
• /
• pp.1-8
• /
• 2010

This study is conducted to use the real-time ultrasound measurement data of Hanwoo as basic data being available to improvement. We used the ultrasound measurement data of 1,125 heads of performance tested cattle and the carcass data after castrating at about 12 months of age, fattened to 30 months, and then sold. For 921 heads of progeny tested cattle, we used test data and slaughter data. Heritabilities of ultrasound data for longissimus muscle area and backfat thickness measured at 12 months of age were estimated as 0.57 and- 0.41, respectively, and at 24 months of age, it was 0.57 and- 0.60, respectively, with high heritability. However, in estimation value of heritability containing ultrasound measurement for percent intramuscular fat, it showed low and medium heritability as 0.14 at 12 months of age and 0.22 at 24 months of age for each. The longissimus muscle area, backfat thickness, and percent intramuscular fat of ultrasound measure traits and longissimus muscle area, backfat thickness, marbling score of carcass traits genetic correlation of at 12 months of age were estimated as 0.616, 0.544, 0.501, respectively and at 24 months of age, it showed high genetic correlation as 0.894, 0.937, 0.263, respectively. As a result of ranking correlation between selection index by using weight, carcass traits at 12 months of age and selection index based on ultrasound measurement data which has high genetic correlation, in data of ultrasound measurement at 12 months of age, it showed high ranking correlation as that selection index of young bull was 0.140 and that of proven bull was 0.843.