• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.975-985
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• 2021

The sufficient amount of protein supply is crucial for improving the growth performance of growing beef cattle. In addition, due to the improvement in the genetic potential of the carcass weight of Hanwoo steers, dietary protein requirements may be increased during the rapid growth period. Accordingly, the dietary crude protein (CP) level in growing Hanwoo steers has been increasing in the field. However, little scientific evidence is available in relation to this. Therefore, this study was conducted to test whether a higher dietary CP level than convention would improve the growth performance and body metabolism in growing Hanwoo steers. Fifty growing Hanwoo steers were randomly divided into two groups and fed either a commercial diet (CON) or a higher CP (HCP) concentrate mix, provided with a similar level of dietary energy. Tall fescue hay was provided ad libitum. The dietary CP level did not affect growth performance and blood metabolite. Nitrogen intake, predicted nitrogen excretion, and retained nitrogen were higher in the HCP group than in the CON group (p < 0.01). Although there was no difference in the nitrogen utilization efficiency, the growth efficiency per retained nitrogen decreased in the HCP group (p = 0.02). A higher dietary CP level may increase nitrogen retention in growing Hanwoo steers without improving growth performance, which leads to reduced growth efficiency per retained nitrogen. Furthermore, considering the high price of feed protein and increased nitrogen excretion to the environment, a further increase in the protein level may not be sustainable.

• Korean Journal of Agricultural Science
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• v.45 no.1
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• pp.84-93
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• 2018

This study was conducted to develop a pasture feeding program for reducing the Hanwoo feeding cost. Italian ryegrass (IRG) is a major plant which is abundantly produced in the southern area of South Korea. Locally produced Italian ryegrass has a 30 - 50% reduced pasture cost compared to imported pasture grasses. We hypothesized that Italian ryegrass feed could reduce the feeding cost but not change the physiological characteristics of the Hanwoo steers in the feedlot. Four treatments (Control, short fed IRG silage, long fed IRG silage, and IRG hay) in a completely random design were used to feed 27 Hanwoo steers. Three or four steers were fed in the same pen, and 8 pens were used for the treatments. Blood was drawn from each steer on the first week of every month from 11 to 30 months. Overall, the average daily gain and feed efficiency were not different among the treatments (p < 0.05) except for the final fattening diets (p < 0.05). The long fed IRG silage group had a low ADG compared to the other groups (p < 0.05). The serum non-esterified fatty acid and glucose concentrations were reduced during the fattening periods (p < 0.05); however, the serum albumin, total proteins, triglycerides, and phosphorus were increased during the fattening periods (p < 0.05). The carcass weight, longissimus muscle area and back-fat thickness were low in the long fed IRG silage group (p < 0.05). The IRG diet induced saturated fatty acids in the longissimus dorsi (p < 0.05). These results show that the IRG diet increased the serum triglycerides but reduced the glucose level at the final fattening diet and decreased the meat yield score in Hanwoo steers.

• 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.

• Food Science of Animal Resources
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• v.32 no.5
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• pp.591-597
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• 2012

This study was conducted to compare meat quality traits related to the tenderness of longissimus muscles obtained from domestic and imported steers. A total of 12 steers from three breeds were slaughtered, and were graded as quality grade 2. They were composed of 4 Hanwoo and 4 Holstein steers (domestic) as well as 4 Angus steers (imported from Australia and gained for six months in Korea until slaughtered). The longissimus lumborum muscles were separated and were stored at $4^{\circ}C$ for 7 and 14 d. Sarcomere length of Hanwoo was significantly shorter than Holstein and Angus at storage day 14 (p<0.05). The myofibrillar index was significantly lower on Hanwoo than Angus at ageing day 7, and was significantly lower than Holstein and Angus steers at storage day 14 (p<0.05). Total collagen contents of Hanwoo and Angus steers were significantly higher than Holstein on storage day 7 (p<0.05), whereas soluble collagen contents of Holstein were significantly higher than Hanwoo and Angus on storage days 7 and 14 (p<0.05). There was no significant difference in the fatty acid composition of the three breeds (p>0.05). Glutamic acid contents of Hanwoo and Angus steers were higher than those of Holstein steers at ageing day 7 and 14 (p<0.05). The results of this study have shown that there were no dramatic differences between beef from the three breeds that were fattened for 6 months under equal conditions.

• Animal Bioscience
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• v.34 no.4
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• pp.621-632
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• 2021

Objective: This study was conducted to investigate the effects of supplementation with rumen-protected γ-aminobutyric acid (GABA) on carcass characteristics and meat quality of Hanwoo steers. Methods: Eighteen Hanwoo steers with an average initial weight of 644.83±12.91 kg were randomly allocated into three different groups. Each group consisted of 6 animals that were treated with different diets formulated based on the animals' body weights. The control (C) group was fed a basal diet consisting of concentrate and rice straw with 74% total digestible nutrients (TDNs) and 12% crude protein (CP). The two other groups were treatment groups; one group was fed a basal diet (74% TDNs and 12% CP) supplemented with rumen-protected GABA at a dose of 150 mg/kg feed, and the other group was fed a basal diet (74% TDNs and 12% CP) supplemented with GABA at a dose of 300 mg/kg feed. Results: The GABA supplementation significantly contributed to better growth performance (p<0.05), especially the weight gain and average daily gain. It also contributed to the lower cooking loss (p<0.05), improvements in essential antioxidant enzymes and stable regulation of antioxidant activities in the longissimus lumborum of Hanwoo steers, as represented by the lower formation of malondialdehyde content within the meat, the inhibition of myoglobin oxidation indicated by the retention of the oxymyoglobin percentage, and the suppression of metmyoglobin percentage during cold storage (p<0.05). Conclusion: Higher doses of GABA may not significantly promote better animal performance and meat quality, suggesting that dietary supplementation with GABA at a dose of 100 ppm is sufficient to improve the meat quality of Hanwoo steers.

• Food Science of Animal Resources
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• v.41 no.1
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• pp.45-58
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• 2021

This study investigated the dietary effect of total mixed ration (TMR) based on high roughage content on the growth performance, carcass characteristics, and meat quality of Hanwoo steers. Twenty-four Hanwoo steers (average body weight, 195.3±4.7 kg; age, 8.5 mon) were randomly allocated to three experimental groups according to forage and concentrate ratio (DM basis): 25:75 (control), 50:50 (T50), and 70:30 (T70). Productivity in the fattening period and final body weight were significantly higher in the control. Average daily gain and feed conversion ratio were the same among treatments. Serum parameters, cholesterol, blood urea nitrogen, and total protein were higher in the control. Carcass weight was comparable in the control and T50 but feeding more roughage was significantly correlated with a higher intramuscular fat. Shear strength and drip loss were higher while n-6/n-3 was lower in T70 compared to the other groups. However, meat color was not significantly different among treatments. In terms of free amino acid contents, glutamic acid and glycine were higher in the control than T50 and T70. Overall, feeding Hanwoo steers with high forage content TMR had the lowest n-6/n-3 ratio of fatty acid content but highest intramuscular fat, shear strength, and drip loss. High forage content TMR is the best feed for Hanwoo steers that gives more benefits for human health and consumption but also provides the best meat grade and quality, which is important in the beef market in Korea.

• Journal of Animal Science and Technology
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• v.64 no.6
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• pp.1077-1091
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• 2022

This study was conducted to determine the rumen fermentation dynamics of lupin flakes and elucidate the effects of lupin flake supplementation on the growth performance, blood metabolites, and carcass characteristics of Hanwoo steers. In vitro and in situ trials of lupin grains and lupin flakes were conducted using three Hanwoo cows with rumen fistulas. The feeding trial included 40 early-fattening Hanwoo steers randomly divided into four groups: control, T1, T2, and T3. Their formula feed contained 0%, 3%, 6%, and 9% lupin flakes, respectively. In vitro rumen pH and ammonia concentrations were lower in the lupin flake group than in the lupin grain group after 6 and 24 h of incubation, respectively (p < 0.05). Concentrations of propionate, butyrate, and total volatile fatty acids were higher in the lupin flake group than in the lupin grain group after 12 h of incubation (p < 0.05), as was the crude protein disappearance rate at 9 and 12 h of rumen fermentation (p < 0.05). Supplementation with lupin flakes did not affect the average daily gain. Compared to that in the control group, dry matter intake was lower in the lupin flake-supplemented groups (p < 0.05); the feed conversion ratio was lower in T2 and T3 (p < 0.05); and plasma total protein concentration in 29-month-old steers was lower in T1 and T3 (p < 0.05). Plasma triglyceride concentration was lower in the lupin flake-supplemented groups than in the control group (p < 0.05). The incidence rate of yield grade A was higher in T1 and T2 than in the control group; the incidence rate of meat quality 1⁺ grade or higher was highest in T2. The carcass auction price was higher in T2 than in the other groups. Overall, compared to whole lupin grains, lupin flakes seem to more substantially affect rumen ammonia concentrations and crude protein disappearance rate. Additionally, we suggest that supplementation with 6% lupin flake formula feed exerts positive effects on the feed conversion ratio, yield grade, and quality grade of Hanwoo steers.

• Animal Bioscience
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• v.37 no.1
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• pp.142-150
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• 2024

Objective: This study was conducted to assess effects of heat stress on growth performance, physiological parameters, and blood profiles of Hanwoo steers during early-fattening period in climate chambers. Methods: Four Hanwoo steers (body weight, 454.3±10.9 kg; age, 14±0.1 month) were allocated into four levels of temperature-humidity index (THI) in a 4×4 Latin square design for 21 days (pre-adaptation, 7 d; heat stress, 7 d; post-adaptation, 7 d) per period. Experimental treatments were assigned according to THI chart based on National Institute Animal Science (NIAS, 2022): Comfort (25.5℃ to 26.5℃, 60%; THI 73 to 75), Mild (28℃ to 29℃, 60%; THI 77 to 79), Moderate (29.5℃ to 30.5℃, 80%; THI 82 to 84), and Severe (31℃ to 32℃, 80%; THI 85 to 86) in separate climatic controlled chambers. Results: The dry matter intake (DMI) of the formula feed was lower in Severe compared to Mild and Comfort (p<0.05). The DMI of rice straw was the lowest in Severe and lower in Moderate than Comfort and Mild (p<0.05). Both average daily gain and feed conversion ratio of Severe and Moderate were lower than those of Mild and Comfort (p<0.05). Water intake was the highest in Severe and lower in Moderate compared with Comfort and Mild (p<0.05). Heart rate and rectal temperature increased as THI level increased (p<0.05). Glucose was the lowest in Severe and lower in Moderate compared to Comfort (p<0.05). On the contrary, non-esterified fatty acid was the highest in Severe and lower in Moderate compared with Comfort (p<0.05). Blood urea nitrogen of Moderate and Severe were higher than those of Comfort and Mild (p<0.05). Cortisol increased as THI increased (p<0.05). Conclusion: This study demonstrated the negative effects of heat stress on the performance and physiological responses of Hanwoo steers during the early-fattening period. In addition, it is judged that the THI chart for Hanwoo steers of National Institute of Animal Science (2022) was properly calculated.

• Korean Journal of Agricultural Science
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• v.46 no.3
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• pp.451-460
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• 2019

The aim of this study was to investigate the effects of dietary supplementation of acetaminophen on feed intake and growth performance of Hanwoo steers in the summer. Eight steers participated in a twelve-week experiment. The steers were randomly assigned into one of two treatments: Control and acetaminophen supplementation. Commercial acetaminophen was top-dressed to a concentrate mix at a rate of 3 g/kg based on dry matter. Individual feed intake was measured daily during the entire period of the experiment, and the intake of forage and concentrate diet were measured separately. The body weight of the steers were measured every 4 weeks. During the experimental period, ambient temperatures were recorded using an automatic temperature and humidity recorder. Acetaminophen had no effect (p > 0.05) on body weight, average daily gain, dry matter intake (DMI) and feed conversion ratio. Numerically, total DMI and concentrate DMI in the acetaminophen treated group were 5.7% and 7.6% lower than those of the control group, respectively, and the daily gain was 9.7% higher. As a result, the feed conversion rate of the acetaminophen treated group improved by 17% compared to the control; however, it was not statistically significant (p = 0.237). The results of this study suggest that acetaminophen supplementation may reduce the feed conversion ratio of Hanwoo steers under high temperature stress. However, further studies are needed to confirm the optimal level of acetaminophen supplementation which has a significant effect on the intake and weight gain of Hanwoo steers in the summer.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.3
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• pp.366-374
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• 2019

Objective: The purpose of this study was to determine the effects of feeding ethanol on growth performances, carcass characteristics, and lipid metabolism of finishing Korean cattle (Hanwoo) steers. Methods: Thirty (30) Hanwoo steers (average 25.1 months of age, body weight 660.1 kg) were assigned to three treatments: control (0% ethanol), E-3 (1.44% ethanol for 3 months), or E-5 (0.72% ethanol for 2 months followed by 1.44% ethanol for 3 months). The animals were allotted by treatment group into six pens and fed concentrate and perennial ryegrass. Ethanol (30%, v/v) was supplemented into drinking water twice a day to meet final concentrations based on average water consumption of finishing Hanwoo steers. Results: There were no statistical differences among the groups in final body weight, average daily gain, or carcass yield grade indices such as cold carcass weight, fat thickness, and loin area. The marbling score tended (p = 0.228) to increase with the highest score (6.7) in the E-5 group followed by 6.3 and 6.0 in E-3 and control groups, respectively. The appearance frequencies of quality grades of $1^{{+}{+}}$ (the best), $1^{+}$, 1, and 2, were; 30%, 50%, 0%, and 20% for control, 10%, 80%, 10%, and 0% for E-3, and 10%, 80%, 0%, and 10% for E-5 groups, respectively, indicating improvements of quality grades by feeding ethanol. Concentrations of serum glucose tended to decrease whereas those of insulin and non-esterified fatty acid to increase by feeding ethanol (E-3 and E-5; p>0.05). Conclusion: Feeding ethanol directly into drinking water of finishing Hanwoo steers stimulated lipogenesis in intramuscular adipose tissue (marbling) and thereby improved carcass quality grade. The serum metabolites results supported the hypothesis of lipolysis of existing adipose tissue, such as abdominal fats, and lipogenesis in intramuscular adipocytes.