Growing Hanwoo Steers Research Articles

Effects of Dietary Fat Level of Concentrate Mix on Growth Performance, Rumen Characteristics, Digestibility, Blood Metabolites, and Methane Emission in Growing Hanwoo Steers.

This study investigated the effect of different dietary fat levels in concentrate mixes on the growth performance, rumen characteristics, digestibility, blood metabolites, and methane emissions in growing Hanwoo steers. Thirty steers (386 ± 24.6 kg of body weight [BW]; 12 months old), blocked by BW, were randomly assigned to three dietary treatments with varying fat concentrations in concentrate mix (48, 74, and 99 g of ether extract per kg dry matte [DM]). The fat intake of the low-fat treatment represented 4.15% of the total dry matter intake (DMI), while the medium- and high-fat treatments accounted for 5.77% and 7.23% of total DMI, respectively. Concentrate mix DMI decreased with increasing fat level (p < 0.01). The growth rate and digestibility did not significantly differ based on the fat level (p > 0.05). As the fat level increased, propionate in the total ruminal volatile fatty acids increased, and butyrate and acetate-to-propionate decreased (p < 0.01). Cholesterol in blood serum increased significantly with increasing dietary fat levels (p < 0.01). Methane emissions exhibited a linear decrease with increasing fat level (p < 0.05). In conclusion, elevating fat content in the concentrates up to 100 g/kg DM reduced methane emissions without compromising the growth performance of growing Hanwoo steers.

Effects of the crude protein concentration on the growth performance and blood parameters in growing Hanwoo steers (Bos taurus coreanae)

Effects of the crude protein concentration on the growth performance and blood parameters in growing Hanwoo steers (Bos taurus coreanae)

Determination of in situ degradation parameters and feeding level of pineapple (Ananas comosus L.) cannery by-product to Hanwoo steers.

ObjectiveThe objectives of this study were to determine the in situ degradation parameters and appropriate feeding level of pineapple cannery by-products (PCB) based on the growth performance and blood parameters of growing Hanwoo (Bos taurus coreanae) steers fed various levels of PCB.MethodsTwo ruminally cannulated Holstein cows were used for in situ disappearance rate measurements. Nylon bags (5×10 cm, 45 μm pore size) filled with 5 g of PCB in triplicate were inserted into the ventral sac of the two cannulated Holsteins cows and incubated for 0, 2, 4, 8, 16, 24, and 48 h. A total of 16 castrated growing Hanwoo steers (12.5±0.5 months old, 302.9±25.7 kg of initial body weight [BW]) were used for the experiment. Animals were stratified by initial BW and then randomly assigned to one of four experimental diets (0%, 1.5%, 3.0%, or 6.0% of PCB, on the dry matter [DM] basis) fed for 91-d, including 30-d of adaptation.ResultsSoluble fraction a of DM and crude protein (CP) was 61.9% and 86.0%, fraction b of DM and CP was 32.7% and 11.2%, and indigestible fraction c of DM and CP was 5.4% and 2.8%. The 6.0% PCB feeding group showed lower productivity compared to animals in the other treatments. Increasing the dietary level of PCB did not alter DM intake, but it was numerically lowest in the 6.0% feeding group. The gain to feed ratio was linearly decreased by increasing of PCB. The quadratic broken-line test estimated that 2.5% (DM basis) was the maximum feeding level of PCB in growing Hanwoo steers (y = 0.103 − 0.001×[1.245−x]2, R2 = 0.18).ConclusionDiets containing up to 2.5% PCB can be fed to growing Hanwoo steers without adverse effects on growth performance.

Nutritional value and in situ degradability of fruit-vegetable byproducts and their feeding effects on performance of growing Hanwoo steers.

ObjectiveThis study was conducted to evaluate nutritional value and in situ degradability of fruit-vegetable byproducts and their feeding effects on performance of growing Hanwoo steers.MethodsNutritional value and in situ degradability of cabbage, Chinese cabbage and fruit-vegetable byproducts were assessed. In vivo feeding trial was also performed for 12 weeks. Thirty-six growing steers were randomly allocated into three groups according to body weight (BW) and age in 12 pens (4 replications/treatment) and assigned to one of the three dietary treatments: control (byproduct 0%), FV-B (fruit-vegetable byproduct 20%), and CA-B (cabbage peel 15% plus Chinese cabbage peel 15%, total byproduct 30%).ResultsThe crude protein contents of cabbage, Chinese cabbage and fruit-vegetable byproducts were 18.69%, 20.20%, and 10.07%, respectively. Concentrations of neutral detergent fiber (NDF) were higher in cabbage (22.31%) and Chinese cabbage (28.83%) than fruit-vegetable (13.94%). Higher concentrations of non-fiber carbohydrate were observed for fruit-vegetable (66.72%) than cabbage (44.93%) and Chinese cabbage byproducts (24.69%). The effective degradability (ED) of both dry matter (DM) and NDF for fruit-vegetable byproduct (DM, 84.69%; NDF, 85.62%) was higher (p<0.05) than cabbage (DM, 68.47%; NDF, 55.97%) and Chinese cabbage byproducts (DM, 68.09%; NDF, 54.22%). The DM intake was not different among treatments because the amount of feed was kept constant according to the BW of growing steers to prevent overweight during the growing period. The average daily gain during the whole experimental period was not different among treatments (1.26, 1.25, and 1.34 kg/d for control, FV-B, and CA-B). The ED of both DM and NDF degradability of the total mixed ration (TMR) diets were very similar among treatments. Feed conversion ratio during the whole period showed no significant difference among treatments.ConclusionThis study demonstrates that fruit-vegetable and cabbage byproducts up to 20% and 30% (as fed basis), respectively can be included in TMR diets for growing beef cattle.

Replacement of corn with rice grains did not alter growth performance and rumen fermentation in growing Hanwoo steers.

ObjectiveThis study was realized to evaluate the nutritional value of rice grains as a replacement for corn grains in the diet of growing Hanwoo steers.MethodsTwo experimental diets were prepared: i) Corn total mixed ration (TMR) consisting of 20% corn grains and ii) Rice TMR consisting of 20% rice grains, in a dry matter (DM) basis. These treatments were used for in vitro rumen fermentation and in vivo growth trials. In the rumen fermentation experiment, the in vitro DM digestibility (IVDMD), in vitro crude protein digestibility (IVCPD), in vitro neutral detergent fiber digestibility, pH, ammonia nitrogen, and volatile fatty acids (VFA) were estimated at 48 h, and the gas production was measured at 3, 6, 12, 24, and 48 h. Twenty four growing Hanwoo steers (9 months old; body weight [BW]: 259±13 kg) were randomly divided into two treatment groups and the BW, dry matter intake (DMI), average daily gain (ADG), and feed conversion ratio (FCR) were measured.ResultsThe in vitro experiment showed that the IVDMD, IVCPD, and VFA production of the Rice TMR were higher than those of the Corn TMR (p<0.05). The growth trial showed no differences (p>0.05) in the final BW, ADG, DMI, and FCR between the two TMRs.ConclusionThe use of rice grains instead of corn grains did not exhibit any negative effects on the rumen fermentation or growth performance, thereby rice grains with a DM of less than 20% could be used as a starch source in the diet of growing steers.

PSIV-5 Effects of feeding fruit-vegetable byproducts on performance of growing Hanwoo steers

Abstract This study was conducted to evaluate the effect of feeding fruit-vegetable byproducts on the growth of Hanwoo (Korean native beef cattle) steers. The treatments were Control (byproduct 0%), T1 (fruit-vegetable byproduct 20%), and T2 (cabbage peel 15% plus Chinese cabbage peel 15%, total byproduct 30%). The fruit-vegetable byproduct for T1 was produced from a hypermarket, containing various types of fruits and vegetables (orange, apple, tomatoes, onion, etc.). These byproducts were milled and treated with 6 g/kg of sodium metabisulfite for long term storage. The cabbage and Chinese cabbage byproduct for T2 produced from a traditional wholesale market was added as a raw material without pretreatment. Thirty-six steers (initial BW. 287 ± 89kg, 9.1 ± 2.7 months) were allocated into 12 pens (3 steers/pen) for 12 weeks according to BW and age. TMR diets were formulated by the Korean Feeding Standard for Hanwoo (2017) to supply the same nutrient contents (CP 16 % and TDN 73 %). The DMI was not different among treatments because the amount of feed was kept constant according to the BW of growing steers to prevent overweight during the growing period. For ADG, Control (1.03 kg/d) and T2 (0.82 kg/d) were lower (P &amp;lt; 0.05) than T1 (1.41 kg/d) in the 2nd period. On the other hand, ADG of T2 (1.72 kg/d) was higher (P &amp;lt; 0.05) than Control (0.82 kg/d) and T1 (1.16 kg/d) in the 3rd period. Overall, ADG for the whole experimental period was not different among treatments (1.20 kg/d for Control, 1.25 kg/d for T1, 1.16 kg/d for T2). FCR showed no significant difference during the whole period (18.36 for Control, 18.82 for T1, 19.75 for T2). Therefore, this study demonstrated that fruit-vegetable and cabbage byproducts in TMR diets for beef cattle can be replaced by 20 % and 30 %, respectively.

PSXII-33 Effects of quality and inclusion rate of roughages on feed intake, growth, rumen fermentation characteristics, and blood parameters of growing Hanwoo steers (Bos taurus coreanae).

PSXII-33 Effects of quality and inclusion rate of roughages on feed intake, growth, rumen fermentation characteristics, and blood parameters of growing Hanwoo steers (Bos taurus coreanae).

A Study on Changes in Feed Digestibility and Establishment of Energy Requirement for Maintenance of Growing Hanwoo Steers under Severe Heat Stress

A Study on Changes in Feed Digestibility and Establishment of Energy Requirement for Maintenance of Growing Hanwoo Steers under Severe Heat Stress

부산물사료 주원료 사일리지(Biosilage®) 급여가 거세 육성 한우의 행동양식에 미치는 영향

This study was carried out to investigate the effects of a by-product feed-based silage (BF silage) feeding on behavior patterns of growing Hanwoo steers. A total of 10 Hanwoo steers (11 months old, 302kg of body weight) were assigned to 2 dietary treatments: the control (concentrate mix + free access to rice straw), and the treatment (concentrate mix + free access to BF silage). The behavior patterns were observed for 48 hours. The intakes of dry matter (DM) and neutral detergent fiber (NDF) of the treatment group were higher than those of the control group. Eating time, ruminating time and resting time were not different between the control and treatment. But, the intake time per kg DM was higher for the control than treatment. The number of bolus, total chewing frequency, number of ruminating per bolus and number of bolus per minute were not different between the control and treatment. But the chewing frequency per bolus was higher in the treatment than control (p

셀레늄 강화 청보리 사일리지 급여가 비육기 거세한우의 생산성, 혈액성상 및 도체특성과 조직 내 셀레늄 축적에 미치는 영향

본 연구는 다양한 수준의 셀레늄 강화 청보리 사일리지와 무기셀레늄을 급여 시 비육기 거세한우의 생산성, 혈액 성상, 도체특성 및 조직 내 셀레늄 축적에 미치는 영향을 조사하였다. 시험은 거세비육우 20두를 공시하였고, 처리구는 셀레늄 수준에 따라 0.1 ppm Se(대조구), 0.3 ppm Se (T1), 0.9 ppm Se (T2) 및 무기셀레늄 0.9 ppm Se (T3) 급여구로 4처리를 나누어 처리구 구당 5두씩 완전임의 배치하여 90일간 사양시험을 실시하였다. 각 시험사료는 셀레늄 강화 및 셀레늄 무처리 관행 청보리 사일리지를 조합하여 건물기준 30% 함유하도록 배합하였다. 실험사료 내에 셀레늄 강화수준은 사료섭취량과 증체에 영향을 미치지 않았고, 혈중 총 지질과 중성지방농도는 대조구보다 T2구가 유의하게 낮았다(p<0.05). 혈중 면역글로불린은 셀레늄함유량이 많을수록 높게 나타나 T2와 T3구가 대조구보다 유의하게 높았다(p<0.05). 혈중 셀레늄농도는 유기태 셀레늄을 0.9 ppm 급여한 T2구가 가장 높았다(p<0.05). 도체율, 배최장근, 등지방두께, 근내지방도, 육색 및 지방색은 셀레늄급여로 인한 효과가 나타나지 않았다. 또한, 사료 내 셀레늄 수준 및 형태는 육질 및 육량등급 간에 관련성이 형성되지 않았다. 신장, 간장 및 후지 내 셀레늄 함량은 사료 내 셀레늄 강화수준이 증가함에 따라 유의하게 직선적으로 증가하였고(p<0.05), 무기셀레늄급여는 대조구와 유의한 차이가 나타나지 않아, 조직 내 셀레늄함량 증가에 도움이 되지 않았다(p>0.05). 이상의 결과에서 셀레늄 강화 청보리 사일리지 내 존재하는 셀레늄은 조직 내 셀레늄함량을 증가시키기에 유효한 셀레늄급원인 것으로 나타났고, 셀레늄 강화 청보리 최고수준(0.9 ppm Se)으로 급여하여 생산된 한우 후지육 100 g에 함유되어 있는 셀레늄은 성인기준 1일 최소 셀레늄 권장량(<TEX>$40{\mu}g$</TEX>)의 약 69%를 충족시키는 것으로 조사되었다. This study was conducted to investigate the effects of feeding seleniferous whole crop barley silage (WCBS) on the growth performance, blood and carcass characteristics, and tissue selenium deposition infinishing Hanwoo steers. A total of 20 growing Hanwoo steers were selected and assigned to one of the following feed groups: control (0.1 ppm Se), T1 (0.3 ppm Se), T2 (0.9 ppm Se), and T3 (0.9 ppm of inorganic Se). Five steers were allocated to each treatment group, and the trial lasted for 90 days. All experimental diets combined seleniferous and/or non-seleniferous WCBS up to a ratio of 30%. For the T3 diet, 0.9 ppm Se in the form of sodium selenite was added to the control diet. Dietary level and type of selenium did not affect feed intake and body weight gain. Blood total lipid and triglyceride concentrations were significantly (p<0.05) lower in the T2 group than in control. Blood immunoglobulin G concentration increased significantly (p<0.05) with increasing levels of dietary selenium; concentrations were significantly (p<0.05) higher in T2 and T3 than in control. Blood selenium concentration was the highest (p<0.05) in T2. No significant difference was observed in dressing rate, ribeye area, marbling score, meat color and fat color. Further, no association was found between levels and chemical form of dietary selenium and quality and quantity of meat. To the contrary, tissue selenium content in kidney, liver, and hind leg increased significantly (p<0.05) with increasing levels of selenium; however, feeding inorganic selenium did not introduce a significant increase in tissue selenium content of finishing Hanwoo steers. The results indicated that the selenium present in seleniferous WCBS was an effectively absorbable selenium source, suitable for increasing tissue selenium content in beef. Approximately 100 g of hind leg muscle from steers fed on the T2 diet met approximately 69% of the recommended daily selenium requirements.

Effects of Dietary Addition of Bentonite and Probiotics on Meat Characteristics and Health of Hanwoo (Bos taurus coreanae) Steers fed Rice Straw As a Sole Roughage Source (a Field Study)

A study was conducted to determine the dietary effects of Na-bentonite (NaB) and probiotics on meat characteristics and health of Hanwoo steers fed rice straw as a sole roughage source. A total of 24 growing Hanwoo steers (avg BW 232 kg) were assigned to two treatments which included a control diet (concentrate mix and rice straw) and a treatment diet (control diet + 0.5-1.0% NaB + 0.5-1.0% probiotics. The diets were fed for 22 months up to the time the animals were slaughtered. Dietary treatment increased (p<0.05) concentrations of trace minerals such as Zn, Cu, and Fe in the longissimus muscle compared to the control. The treatment diet did not affect cold carcass weight, yield traits such as backfat thickness, longissimus muscle area, yield index, yield grade and quality traits such as marbling score, meat color, fat color, texture, maturity and quality grade. Blood profiles of growing steers were within the normal ranges for healthy cattle. In conclusion, feeding a combination of clay mineral and probiotics to Hanwoo steers fed rice straw as a sole roughage source could have a desirable effect on improving trace mineral retention in longissimus muscle without any deleterious effects on carcass traits of steers.

Effects of Supplementing Microbially-fermented Spent Mushroom Substrates on Growth Performance and Carcass Characteristics of Hanwoo Steers (a Field Study).

This study evaluated the effect of dietary supplementation of microbially-fermented spent mushroom substrates (MFSMS) on weight gain, carcass characteristics, and economic efficiency of Hanwoo steers. Highly cellulolytic bacteria (Enterobacter spp. and Bacillus spp.) isolated from spent mushroom substrates (SMS) stacks were inoculated (1% v/v) into the SMS, which was anaerobically fermented and fed to the steers for 12.6 months during the growing and fattening periods. Growing Hanwoo steers were assigned to the control group without supplementation of Microbially-fermented SMS (MFSMS), to a treatment group with 50% of MFSMS (1/2 of the ad libitum group), and to a treatment group with ad libitum access to SMS (the ad libitum group). All the groups were fed the formulated feed and rice straw. The voluntary intake (DM basis) of MFSMS was 1.6 kg/d during the growing period and 1.4 kg/d during the fattening period. The voluntary rice straw intake decreased by 6 to 11%, but the total voluntary DMI increased by 7 to 15% with MFSMS fed. The increased DMI with MFSMS supplementation resulted in a tendency of increased (p = 0.055) live weight gain by 8 to 12% compared with the control group. At slaughtering, the supplementation of MFSMS increased (p<0.05) the ribeye area by an average of 10 cm2. In conclusion, feeding MFSMS improved growth performance and carcass traits of Hanwoo steers and could successfully replace a part of conventional roughage such as rice straw commonly used in Asian countries.

셀레늄함유 청보리 사일리지급여가 육성기 거세한우의 생산성 및 혈액성상에 미치는 영향

This study was conducted to investigate effects of feeding seleniferous whole crop barley silage (WCBS) on growth performance and blood characteristics in growing Hanwoo steers. A total of 20 growing Hanwoo steers, initially weighing on average 208.8 kg of body weight, were used and treatments were consisted of 1) controls : 0.1 mg/kg Se, 2) T1 : 0.3 mg/kg Se, 3) T2 : 0.9 mg/kg Se by combining seleniferous and/or non-seleniferous WCBS, and 4) T3 : 0.9 mg/kg Se of inorganic Se treatment. Five steers were allocated to each treatment, and the trial was lasted for 90 days. All experimental diets were included to 30% of combination of seleniferous and/or non-seleniferous WCBS, and in T3 diet, sodium selenite that corresponds to 0.9 mg/kg Se was added to control diets. Also, the diets were isonitrogenous and isocaloric among treatments. Dietary level and type of selenium did not affect feed intakes and daily gain, and blood glucose concentration was significantly (p0.05). Blood selenium concentration was significantly (p

거세 한우 육성우 사육밀도가 채식행동에 미치는 영향

This study was carried out to investigate the effects of stocking density on the eating and ruminating behavior of growing Hanwoo steer (Bos taurus coreanae). A total of thirty growing Hanwoo steers were divided into four stocking density groups (G1: 1 head/32 m 2 , G2: 2 heads/32 m 2 , G3: 3 heads /32 m 2 , G4: 4 heads/32 m 2 ) with 3 replicates (12 pens). The results of eating behaviors for 48 hours are summarized as follows: Total intake was higher in 2G, 3G and 4G than in 1G, but not significantly different among thetreatments. Intake of roughage was the highest in 2G (3.32 kg), while 1G (2.85 kg) was the lowest (P 2G> 3G > 4G (P 4G > 2G > 3G (P<0.05). However, stocking density had no effect on drinking and defecating. Eating rate and chewing efficiency were the highest in 4G (P<0.01, 0.05), but

육성기 거세한우의 유지에너지 요구량 결정에 관한 연구

본 시험은 생후 6개월 령의 육성기 거세한우 6두(<TEX>$180.6{\pm}3.1$</TEX> kg)를 공시하여 옥수수 위주의 농후사료 60%와 티모시 건초 40% 비율로 급여하였고 TDN 함량은 71.4%, CP는 14.6%이었다. 시험은 Korean Feeding Standard for Hanwoo (2007)에 따라 일당 증체량 0 kg, 0.4 kg, 0.7 kg/일에 필요한 각각의 TDN 함량 1.70 kg (Low), 2.05 kg (Medium), 2.80 kg (High)의 공시사료를 섭취할 수 있도록 하는 duplicated 3 <TEX>${\times}$</TEX> 3 Latin square design으로 수행하였다. 에너지 수준에 따른 급여사료는 전량 섭취하였고, 일반적으로 건물섭취량의 증가가 반추위 통과속도를 높이기 때문에 소화율이 낮아지지만 본 실험에서는 건물, 조단백질, 조지방, 조섬유의 소화율은 차이가 없었다 (P>0.05). 섭취 에너지 수준별 평균 대사 체중 당 총에너지 섭취량은 180.2, 292.7와 337.2 kcal/<TEX>$BW^{0.75}$</TEX>이었다(P<0.001). 처리구별 총 에너지섭취량이 증가하면서 분으로 손실된 에너지도 51.1에서 99.71kcal/<TEX>$BW^{0.75}$</TEX>로 유의적으로 증가함(P<0.001)에 따라 가소화에너지는 약 70%로 처리 간 차이가 없었다. 뇨로 손실된 에너지는 3.5에서 7.9 kcal/<TEX>$BW^{0.75}$</TEX>로 유의적으로 증가하였고(P<0.03), 반추위 발효과정에서 발생되는 메탄가스에 의한 에너지 손실도 15.0에서 20.5 kcal/<TEX>$BW^{0.75}$</TEX>로 증가하는 경향을 보였다(P=0.06). 체열에 의한 손실량은 수준별로 차이가 없었지만, 총에너지섭취량(GE)에 대한 비율은 60.4, 41.2와 34.1%로 에너지 섭취량이 높아질수록 감소하였다. 대사에너지 섭취량 수준 110.6, 186.3, 209.1 kcal/<TEX>$BW^{0.75}$</TEX>와 각각의 체 축적 에너지 1.67, 65.76, 94.25 kcal/<TEX>$BW^{0.75}$</TEX>의 관계식을 통해 구한 X축 절편 값, 즉 유지를 위한 에너지 요구량은 109.8 kcal/<TEX>$BW^{0.75}$</TEX>로 나타났다. Present experiment was carried out to determine maintenance energy requirements for growing Hanwoo steers. Six Hanwoo steers (BW = <TEX>$180.6{\pm}3.1$</TEX> kg) were used in two 3 <TEX>${\times}$</TEX> 3 latin square design with three different energy intake levels; TDN 1.70 kg (Low), 2.05 kg (Medium), 2.80 kg (High), respectively, based on the Korean Feeding Standards. Each period lasted 18 days including a 14-day adaptation and a 4-day measuring period. The steers were in the head hood chamber system (one cattle per chamber) during each measuring time to measure heat and methane production for 1 day. Dry matter intake was 2,058, 3,256 and 3,881 g/day for Low, Medium and High TDN, respectively. Increase in energy intake did not affect digestibilities of dry matter, crude protein, crude fiber, crude fat, NDF, ADF and nitrogen-free extract. Gross energy intake averaged 180.21, 292.74 and 337.15 kcal/<TEX>$BW^{0.75}$</TEX> for Low, Medium and High TDN, respectively. Energy loss was 28.7% in feces and 2.1% in urine of gross energy intake. Further, energy loss from methane produced during rumen fermentation was 6~8.3%, while body heat loss averaged 34~60%. Intercept of regression equation between ME intake and retained energy indicated that the energy requirement was 109.84 kcal ME/<TEX>$BW^{0.75}$</TEX>.

Effects of Feeding Methods of Total Mixed Ration on Behavior Patterns of Growing Hanwoo Steers

A study was conducted to investigate the effects of methods of feeding a total mixed ration (TMR) on behavior patterns of growing Hanwoo steers. A total of 15 growing steers (13 months old) were assigned to the control (fed roughage and concentrate mix separately), TMR1 (fed restricted TMR), and TMR2 (fed TMR ad libitum) groups. Individual behaviors of steers were observed for 48 hours. Compared with the control, feeding restricted TMR (TMR1) resulted in short eating time, long ruminating time, short chewing time, high frequencies of defecation, urination, and drinking of water, great numbers of boluses and chews, long ruminating time per bolus, low feed value index, high eating and chewing efficiencies (p 0.05). Considering all these results, the wet TMR feeding system induced generally more desirable eating and ruminating behaviors of growing Hanwoo

단백질 균형시험에 의한 한우 거세우의 유지 조단백질 요구량

본 연구는 거세우의 1일 유지 단백질 요구량을 구하기 위해 실시하였다. 평균체중 173.7±26.3kg의 한우 거세우 18두를 공시하여 3수준의 단백질을 급여하면서 질소균형법을 통해 유지 단백질 요구량을 결정하였다. 급여사료의 조단백질(CP) 수준을 조절하기 위하여 분쇄옥수수를 corn gluten meal(CGM)로 0%(LCP), 7.2% (MCP), 14.2%(HCP) 대체하였고, 각 배합사료의 CP 함량은 9.8, 14.0, 18.9% DM 이었다. 1일 사료급여량은 체중의 2.0%로 하면서 배합사료와 볏짚의 비율은 80:20로 동일하게 하였다.CP 섭취량은 LCP, MCP, HCP 구에서 각각 5.1, 7.8, 10.3g/BW0.75 이었고, 단백질 섭취량이 높아지면서 DM 소화율도 LCP 구와 비교하여, MCP 구, HCP 구에서 각각 14%, 20%의 유의성 있는 증가를 보였으며, CP 소화율은 LCP 구와 비교하여 MCP 구 및 HCP 구에서 각각 약 50%, 80% 증가하였다. LCP, MCP, HCP 구에서의 CP 균형은 각각 －0.05, 2.36, 4.07g/ BW0.75 이었고, 대사체중당 CP 섭취량과 CP 축적량과의 관계식에서 CP 균형이 0이 되는 X축 절편, 즉, 유지 단백질 요구량 5.56g/BW0.75 이었다. 본 결과는 일본의 육용종 거세우보다 평균 20% 이상은 높기 때문에 본 연구결과를 적용한 한우 사양표준(농림부, 2002)의 유지 단백질 요구량이 좀 더 낮아져야 할지에 대해서는 증체 단백질 요구량을 포함한 총 단백질 요구량과 그동안의 사양시험 결과들을 수집 분석하는 종합적인 고찰이 필요하다. This experiment was conducted to determine crude protein requirements for maintenance (CPm) of growing Hanwoo steers. Eighteen Hanwoo steers (173.7kg) were allocated randomly to diets with three levels of crude protein in the concentrate by replacing ground corn with corn gluten meal: 0% (LCP), 7.2% (MCP) and 14.2% (HCP), respectively. Hanwoo steers in each treatment were fed diets containing rice straw (20%) and concentrates (80%). CP intake was 5.5, 7.8 and 10.7g/BW0.75 for LCP, MCP and HCP, respectively. Protein balance was －0.05, 2.36 and 4.07g/BW0.75 for LCP, MCP and HCP, respectively. Intercept of the regression equation between CP intake and retained CP indicated that CPm was 5.56g/BW0.75. The estimate of CPm adopted by Korean Feeding Standard (2002) was almost 20% higher than that adopted by Japanese Feeding Standard for Beef Cattle (2000); this would need to be verified with more feeding trial data set including protein requirements for growth.