• Journal of Animal Science and Technology
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• v.55 no.4
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• pp.315-323
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• 2013

This study analyzed optimal slaughter ages and carcass traits to investigate factors that affect farm incomes. Carcass characteristics and economical analysis of 81 Hanwoo steers previously tested (Expt. 1) and 5,826 steers from Gangwon-Do, area A (Expt. 2) were used. In Expt. 1, the strongest relationship was between the slaughter age and the carcass weight based on the $R^2$ value, and the weakest relationship was between the slaughter age and the marbling score based on the $R^2$. The slaughter age, marbling score, and rib-eye area of steers slaughtered from 26 to 31 months of age had a positive effect on income, but back fat thickness had a negative effect. In the economical analysis of Expt. 1, the optimal time for slaughter was 31 months of age. In Expt. 2, composed of steers slaughtered from 26 to 35 months of age in farms site of area A, the income was highest from steers slaughtered at 28 months of age, after which the income decreased. From the results of Expt. 1 and 2, it is evident that the optimal slaughter age of Hanwoo steers is affected by the genetic differences of calves, the feeding program and management, fattening skills, or carcass price. In order to improve the income of individual farms, the slaughter age must be precisely decided by understanding the exact relationship between the feeding cost of Hanwoo steers and slaughter results, such as carcass weight, yield grade and quality grade.

• Journal of Animal Science and Technology
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• v.54 no.6
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• pp.443-448
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• 2012

This study was conducted to investigate changes of blood metabolites and enzyme activities at different slaughter ages of Hanwoo cattle. Blood samples were taken from six hundred thirty two steers (24~33 months of age) and one hundred twenty eight bulls (17~24 months of age) by venipuncture from caudal vein immediately prior to slaughter. Glucose concentrations were linearly increased (P<0.001) with increases of the slaughter age in steers, and blood urea nitrogen (BUN) concentrations were linearly decreased (P<0.001) with increases of the slaughter age in steers. Likewise, glucose and albumin concentrations in bulls were linearly decreased (P=0.009 and P<0.001, respectively) with increases of the slaughter age. BUN, cholesterol, triglycerides, and total cholesterol concentrations were linearly increased (P<0.001, 0.018 and 0.002, respectively), and creatinine concentrations were quadratically increased (P=0.009) with increases of the slaughter age. Activity of gamma glutamyltransferase (${\gamma}$-GT) and aspartate aminotransferase (AST) was linearly increased (P<0.001) with increases of the slaughter age in both steers and bulls, whereas alanine aminotransferase (ALT) was not affected by increasing slaughter age. In addition, the concentrations of ${\gamma}$-GT and AST were higher (P<0.05) for bulls than those of steers at 24 months of age. Increased levels of ${\gamma}$-GT and AST indicate impaired liver function; it may be associated with increases of concentrate level which is a concomitant of the extended fattening periods in Hanwoo feeding. In conclusion, the results in the present study may be one of the useful information for diagnosis of the metabolic disorder in Hanwoo cattle.

• Food Science of Animal Resources
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• v.29 no.5
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• pp.550-556
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• 2009

Two experiments were carried out to investigate the relationship of slaughter age and carcass traits of Hanwoo cattle. A total number of 11,284 heads of cattle (4,624 bulls, 6,120 steers, and 540 females) were used in the experiment (Exp.) 1. In the Exp. 2, 3,887 heads of steers slaughtered at age of 24-36 mon were used. After 24 h post-slaughter chilling, the carcasses were weighed and evaluated by an official grader of carcass traits according to the Korean carcass grading standard. Backfat thickness was the main variable in yield index and grade whereas marbling score was the main variable in carcass quality grade. Meat color was an important factor affecting carcass quality grade of bulls; fat color was an important factor affecting those of steers and females; and maturity was an important factor affecting that of females. After 24-mon-old, extension of slaughter age did not automatically increase the quantity and quality of meat. However, 29 mon of age can be regarded as the optimum time to slaughter steers to attain the highest take home money for farmers.

• Food Science of Animal Resources
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• v.42 no.3
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• pp.455-466
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• 2022

The aim of this study was to assess the occurrence of white striping (WS), wooden breast (WB), and WS combined with WS/WB muscle abnormalities in broilers (Ross 500) at different slaughter ages (34, 41, and 48 d). In addition, the influence of these muscle abnormalities at different slaughter ages on quality characteristics (physical dimensions, pH, color index, and chemical composition) was studied. Overall occurrence of muscle abnormalities was 45%, 92%, and 100% at slaughter ages of 34, 41, and 48 d, respectively. It was found that about 39% from the occurrence of muscle abnormalities was not similar in the same bird (left and right fillets). Breast fillets affected by muscle abnormalities had significantly (p<0.05) higher weight than normal fillets. At slaughter age of 34 d, normal fillets had significantly higher L^* (67.37 vs. 61.73 and 63.05, p<0.05), lower a^* (3.25 vs. 4.87 and 5.18, p<0.05) and b^* (4.02 vs. 5.20 and 5.99, p<0.05) than WS and WS combined with WB fillets; respectively. The changes in chemical composition due to muscle abnormalities were more significant at high slaughter age than at low slaughter age. In conclusion, the occurrence of muscle abnormalities was strongly influenced by slaughter age. Moreover, breast fillets affected by muscle abnormalities had different quality characteristics (proximate composition, color traits, and dimensions) in comparison to normal fillets.

• Journal of Animal Science and Technology
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• v.63 no.1
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• pp.180-190
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• 2021

This study aimed to determine the carcass and meat quality of broiler chickens based on the slaughter age (28, 30, 32, and 34 days). The carcass characteristics included live and carcass weights, carcass rate, dressing rate, and retail cut weight. The meat quality properties were determined through proximate composition, pH, color, water holding capacity (WHC), cooking yield, and shear-force. The broiler chicken live, carcass, breast, thigh, and wing weights significantly increased with the slaughter age (p < 0.05); the tenderloin weight also exhibited a similarly increasing trend. However, the carcass rate of the day 28 sample was significantly lower than the other samples (p < 0.05). The protein and ash contents of the breast exhibited an increasing trend with increasing slaughter age. The protein content of the thigh of the day 28 sample was significantly lower than that of the other samples (p < 0.05), while the ash contents of the day 28 and 30 samples were significantly lower. The redness of the breast showed an increasing trend, and the pH and lightness of the thigh exhibited a decreasing trend with slaughter age. The WHC and cooking yields of the day 30 and 32 breast and thigh samples were significantly higher than those of the day 28 and 34 samples (p < 0.05). The breast and thigh shear-force of the day 30-34 samples were significantly higher than those of the day 28 sample (p < 0.05). The present study showed that even with a twoday difference in slaughter age, the broiler chicken meat quality showed a significant difference in several characteristics.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.405-416
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• 2013

This aim of this study was to estimate the most reasonable slaughter month for Hanwoo steers according to carcass traits. Carcass trait data on Hanwoo steers (17,249 head) were collected from October 2008 to September 2011. To measure the regression coefficients, Hanwoo steers were divided into two groups according to slaughter age: early (25 to 31 months) and late (32 to 38 months) groups. Regression coefficients of carcass traits according to slaughter age were significantly different (p<0.001) with the exception of PPKG (estimated auction price per 1 kg of carcass weight) in the early slaughter age group and MAR (marbling score, p<0.05) and PPKG (p<0.05) in the late slaughter age group. To obtain a positive gross margin, Hanwoo should be slaughtered at around 28 months of age.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.4
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• pp.605-610
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• 2006

The objective of the present experiment was to determine the effects of slaughtering at different ages and the use of a commercial probiotic (115-Biogallinox) in broiler diets on the color properties of carcasses, during the first 24 h following slaughter. Ross 308 male broiler chickens obtained from a commercial hatchery were raised to either 35 or 42 days of age. Chickens were fed with different levels of probiotic ($P_0$: 0.0%, $P_1$: 0.1% and $P_2$: 0.2%) containing Saccharomyces cerevisiae during the experimental period. At the end of the trial all birds were slaughtered and then stored at $3^{\circ}C$ for 24 h. The pH and skin colour of carcasses were determined 1, 3, 7, 10, 13, 17 and 24 h after slaughter. Although the use of probiotic and post-mortem ageing time affected the pH (p<0.01), it was not affected by slaughter age (35 and 42 days) (p>0.05). The highest pH values occurred in carcasses of broilers fed 0.2% probiotic. The pH values of carcasses decreased with post-mortem ageing time (p<0.01). Main factors (treatment, slaughter age and post-mortem ageing time) had an effect on colour ($L^*$, $a^*$ and $b^*$) values (p<0.01). $L^*$ values of 42d-old slaughter and $P_2$ group were lower than those of 35d-old slaughter and other probiotic groups. The $a^*$ and $b^*$ values of 35d-old slaughter were lower than those of 42d-old slauhgter. The $a^*$ and $b^*$ values increased during post-mortem ageing (p<0.01). It was determined that changing of the colour traits of broiler carcasses was correlated with probiotic, pH and post-mortem ageing time. Also, it was observed that darkness of carcass colour increased as time progressed.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.9
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• pp.1227-1232
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• 2008

Carcass characteristics data of Hanwoo (N = 1,084) were collected from two stations of the National Livestock Institute of Animal Science (NIAS), Korea and records from thirteen individual cow-calf operators were analyzed to estimate variance and covariance components and the effect of different slaughter endpoints. Carcass traits analyzed were cold carcass weight (CWT, kg), REA (rib eye area, cm2), back fat thickness (mm) and marbling score (1-7). Four different models were examined. All models included sex and contemporary group as fixed effects and the animal's direct genetic potential and environment as random effects. The first model fitted a linear covariate of age at slaughter. The second model fitted both linear and quadratic covariates of age at slaughter. The third model fitted a linear covariate of body weight at slaughter. The fourth model fitted both linear covariates of age at slaughter and body weight at slaughter. Variance components were estimated using the REML procedure with Gibb's sampler. Heritability estimate of CWT was in the range of 0.08-0.11 depending on the model applied. Heritability estimates of BF, REA and MS were in the ranges of 0.23-0.28, 0.19-0.26, and 0.44-0.45, respectively. Genetic correlations between CWT and BF, between CWT and REA, and between CWT and MS were in the ranges of -0.33 - -0.14, 0.73-0.84, and -0.01- 0.11, respectively. Genetic correlations between REA and BF, between MS and BF and between REA and MS were in the ranges of -0.82 ~ -0.72, 0.04~0.28 and -0.08 ~ -0.02, respectively. Variance and covariance components estimated varied by model with different slaughter endpoints. Body weight endpoint was more effective for direct selection in favor of yield traits and body weight endpoints affected more of the correlated response to selection for the traits of yield and quality of edible portion of beef.

• Journal of Animal Science and Technology
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• v.64 no.1
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• pp.143-154
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• 2022

This study was conducted to evaluate the relationship among market weight, slaughter age, yield grade, and primal cut yield in Hanwoo. A total of 403 Hanwoo (Korean native cattle) was assessed for carcass traits such as carcass cold weight, backfat thickness, ribeye area, dressing percentage, yield index, and marbling score. The production yield of the individual major primal cuts of Hanwoo beef was also measured. Carcass cold weight, ribeye area, and backfat thickness, which affect meat quality increased with increased market weight (p < 0.05). The production yield of the ten major primal cuts also increased with increased market weight (p < 0.05). In terms of slaughter age, carcass cold weight, ribeye area, and backfat thickness all increased from 25 months to 28-29 months, and the production yield of all prime cuts also increased with increasing slaughter age. According to the meat yield grade, carcass cold weight and backfat thickness increased from grade A to grade C, although the ribeye area was not affected. The combined findings of the study suggest that slaughtering Hanwoo at the weight of 651-700 kg and 701-750 and age of 28.23 and 29.83 months could be desirable to achieve the best quality and quantity grade of Hanwoo beef. However, the positive correlation of carcass cold weight and backfat thickness, and the negative correlation of the yield index according to primal cuts yield indicated that it is necessary to couple the slaughtering management of cattle with improved genetic and breeding method of Hanwoo to increase the production yield of the major prime cuts of Hanwoo beef.

• Journal of agriculture & life science
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• v.45 no.6
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• pp.109-114
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• 2011

The objective of this study was to investigate the effects of environments (farms born, testing groups, age at the tests, date at slaughter, ages at slaughter) on body weights at 6, 12, 18 and 24 months of ages, body type measurements at 18 months of age and carcass characteristics in Hanwoo steer populations that were collected from commercial farms and reared in a progeny testing station. Performances of a total of 1,838 steer calves set for tests from 2004 to 2008 were recorded. Carcass characteristics were the carcass grading results evaluated and data collected slaughter scores at 24 months of age. For growth traits of all age classes and body type traits measured at 18 months of age, farms born, test group and linear covariate of age at test were fit in the models. For carcass traits, date at slaughter and linear covariate of ages at slaughter were fit in the models. Effect of farm at birth was not significant for body weight at 24 months of age. Carcass weight, eye muscle area, yield score and back fat thickness were affected by dates at slaughter but not by the ages at slaughter. Marbling score, however, was affected by these two effects. Farms at birth did not seem to affect body type measures greatly. This study will be utilized for Hanwoo Steers genetic evaluation.