Hanwoo Steers Research Articles

Impact of Forage Sources on Ruminal Bacteriome and Carcass Traits in Hanwoo Steers During the Late Fattening Stages.

This study examined the effects of different forage sources on the ruminal bacteriome, growth performance, and carcass characteristics of Hanwoo steers during the fattening stage. In Korea, where high-concentrate feeding is common, selecting suitable forage is crucial for sustainable beef production. Fifteen 23-month-old Hanwoo steers, weighing an average of 679.27 ± 43.60 kg, were fed the following five different forage sources: oat hay (OAT), rye silage (RYE), Italian ryegrass (IRS), barley forage (BAR), and rice straw silage (RSS), alongside 1.5 kg of dry matter concentrate daily for five months. Carcass traits were evaluated post-slaughter, and rumen fluid samples were analyzed using full-length 16S rRNA gene sequencing to determine the bacteriome composition. The forage source significantly affected the alpha-diversity indices and bacteriome biomarkers linked to the feed efficiency and ruminal fermentation. Differences in the backfat thickness and meat yield index were noted, with alpha-diversity indices correlating with carcass traits. The phylum Planctomycetota, especially the family Thermoguttaceae, was linked to nitrogen fixation in high-protein diets like IRS, while the genus Limimorpha emerged as a biomarker for the meat yield. These findings highlight the importance of forage selection during late fattening to optimize beef production, considering diet and bacteriome shifts.

Methane emission, nitrogen excretion, and energy partitioning in Hanwoo steers fed a typical TMR diet supplemented with Pharbitis nil seeds.

Two in vivo experiments were conducted to evaluate the potential of Pharbitis nil seeds (PA) as an anti-methanogenic additive to ruminant feed. In experiment 1, six Hanwoo steers (459.0 ± 25.8 kg) were fed either a total mixed ration (TMR; 32-d period) or TMR supplemented with PA at 5% dry matter (DM) intake (TMR-PA; 45-d period) for two consecutive periods. Fecal and urine outputs were measured in an apparent digestibility trial in both periods. Methane (CH4) yield and heat energy (HE) were measured using respiratory chambers equipped with gas analyzers. In experiment 2, five rumen cannulated Holstein steers (744 ± 35 kg) were fed the same TMR or TMR-PA diets for 40 days; rumen samples were collected at 0, 1.5, and 3 h after feeding on the last day of the feeding period. In experiment 1, although there were no differences (p > 0.05) in nutrients or gross energy intake (GEI) between the groups, an increase (p < 0.05) in the apparent digestibility of DM (9.1%) and neutral detergent fiber (22.9%) was observed in the TMR-PA fed Hanwoo steers. Pronounced decreases (p < 0.05) in CH4 (g/Kg DM; 17.1%) and urinary N excretion (% N intake; 7.6%) were observed in the TMR-PA group, leading to a 14.7% increase in metabolizable energy intake (% GEI). However, only a numerical increase (p > 0.05) in retained energy was observed due to the increase in HE loss. In experiment 2, a drastic decrease (p < 0.05) in rumen ammonia concentration (56.3%) associated with an increased (p = 0.091) rumen short-chain fatty acid concentration 1.5 h after feeding were observed in TMR-PA fed Holstein steers. A 26.6% increase (p < 0.05) in the propionate proportion during the treatment period clearly reflected a shift in the ruminal H2 sink after 3 h of feeding. A 40% reduction (p = 0.067) in the relative abundance of rumen protozoa Entodinium caudatum was also observed. It was concluded that PA could be a natural feed additive for CH4 and N emission abatement.

PSVII-22 Age-related transcriptome changes associated with beef quality in longissimus thoracis muscle of Hanwoo steer

Abstract Understanding age-associated transcriptome changes in longissimus thoracis (LT) muscle is important for determining beef quality and yield characteristics. We investigated age-related transcriptome changes in LT of Hanwoo (Korean cattle) steers. Hanwoo steers [n = 11; initial body weight (BW) = 354 ± 5.53 kg; age, 12 ± 0.28 mo] were used. The LT samples were biopsied between the 11th and 12th ribs at 12, 18, and 24 mo of age. Steers were slaughtered at 31 mo of age (789 ± 17.7 kg) and LT samples were collected. For transcriptome analysis, six LT samples from steers at each of the four ages were selected based on initial BW, carcass weight, rib eye area, carcass quantity, and beef quality grades. Transcriptomic profiles at various ages were measured by RNA sequencing (RNA-seq). A total of 13,753 transcriptomes were identified, and a total of 2,522 differentially expressed genes (DEGs: 743 up-regulated and 1088 down-regulated genes) between 12 mo and 31 mo of age were identified (false discovery rate &amp;lt; 0.05 and |fold change| ≥ 2). Gene ontology annotation analysis of these DEGs showed several significant (P &amp;lt; 0.05) terms including blood vessel morphogenesis, external encapsulating structure, and cell adhesion molecule binding. Pathway analysis of these DEGs revealed several significant (P &amp;lt; 0.05) Kyoto encyclopedia of genes and genomes (KEGG) pathways including pathways in cancer, MAPK signaling pathway, and cell adhesion molecules. Transcriptomic expression patterns of the up-regulated and the down-regulated genes of the significant functional annotation terms between 12 mo and 31 mo were validated using all animals by quantitative real-time polymerase chain reaction analysis. Protein expression patterns of nuclear receptor subfamily 4 group A member 1, coagulation factor II thrombin receptor, and growth arrest and DNA damage inducible alpha genes were validated by Western analyses. In conclusion, age-related gene expression changes suggest that pathways involved in the regulation of vascular morphogenesis and cell adhesion molecules provide novel insights into understanding the molecular mechanisms responsible for beef quality and carcass weight in beef cattle.

PSXIII-27 Effects of long-term dietary supplementation of nitrate on enteric methane production and performance of Hanwoo steers

Abstract Nitrate (NO3-) has been recognized as an effective dietary additive to reduce enteric methane (CH4) production in ruminants. Two experiments were performed to evaluate the effects of long-term supplementation and method of supplementing calcium ammonium nitrate (CAN) on enteric CH4 production in Hanwoo steers. In Exp. 1, Hanwoo steers [n = 20; body weight (BW) = 348 ± 18 kg] were divided into two groups of 10, and were assigned to one of the two diets 1) CON, 500 g/kg timothy hay and 500 g/kg commercial concentrate, or 2) CAN, basal diet top-dressed with 2.5% CAN [1.578% NO3- in the dietary dry matter (DM)] for 115 d in a completely randomized design. Measurement of CH4 was performed for 3 d starting from d 21, d 51, d 80 and d 112 using whole body respiratory chambers (RC). Rumen fluid and blood samples were collected on d 25 and d 26 of the feeding trial, respectively. In Exp. 2, the animals were re-grouped (476 ± 21 kg) and fed the same basal diet supplemented with 2.0% CAN (1.262% NO3- in the dietary DM) incorporated in the concentrate pellet (P-CAN). Methane was measured on d 19 and d 45 for 3 d. In Exp. 1, CAN supplementation decreased (P &amp;lt; 0.05) DM intake (DMI) of the steers both in the barn and RC. However, no negative effects on average daily gain or feed conversion ratio were observed. Also, no potential toxicity of NO3- was observed based on blood methemoglobin concentrations (all samples &amp;lt; 2.5% of total hemoglobin). A decrease (P &amp;lt; 0.05) in CH4 production (g/d) caused by decreased DMI was noted in CAN throughout the feeding trial. However, CH4 yield (g/kg DMI) decreased (P &amp;lt; 0.05) only in the beginning phase (d 21) and did not differ (P &amp;gt; 0.05) thereafter. Ruminal pH, ammonia and total volatile fatty acid concentration did not differ between treatments (P &amp;gt; 0.05), but CAN increased and decreased (P &amp;lt; 0.0001) acetate and butyrate proportions, respectively. Steers fed CAN had greater ruminal abundance of Ruminococcus sp. (P &amp;lt; 0.05), Succiniclasticum (P = 0.066), and Selenomonas ruminantium (P = 0.073), but a reduced (P &amp;lt; 0.05) abundance of Methanobrevibacter ruminantium (P = 0.073). In Exp. 2, P-CAN did not exert any effects on DMI, CH4 production, CH4 yield and other production parameters. Overall, CAN can be used as a feed additive for beef cattle in the long-term without NO3- intoxication or any negative effects on growth performance. However, lack of persistent decrease in CH4 yield suggested the need of further evaluation of CAN under different dietary conditions. Furthermore, incorporating CAN in the concentrate pellet can be a suitable approach, since top-dressing may alter the organoleptic properties of diets that may reduce DMI of the steers.

PSVII-9 Improvement of feed efficiency in Korean Hanwoo cattle: investigation of feed intake and analysis of residual feed intake (RFI)

Abstract Feed efficiency is an important economic trait in beef cattle production, and improving feed efficiency can reduce production costs and environmental impact. Residual feed intake (RFI) is a useful measure of individual feed efficiency, representing the difference between the actual feed intake of an animal and its predicted feed intake based on its body weight (BW) and growth. This study aimed to investigate feed intake and analyze RFI in Hanwoo cattle to improve feed efficiency. Data were collected from 120 Hanwoo steers (9 to 11 mo old) from six different test stations across the country. Individual daily feed intake of concentrates and forage was recorded over 70 d, and BW was measured at the beginning and end of the feeding trial. Daily feed intake was calculated using the TDN values of the concentrates and forage. Expected feed intake was estimated using a linear regression model based on metabolic BW and daily gain. RFI was calculated as the difference between expected and actual feed intake. Average daily gain ranged from 1.05 to 1.71 kg/d, and average daily feed intake ranged from 5.10 to 7.72 kg/d across the test stations. RFI values ranged from -0.84 to 0.95 kg/d, indicating significant variation in feed efficiency among the animals. This study provides valuable information on feed intake and RFI in Hanwoo cattle. Further research with a larger dataset is needed to develop a genetic evaluation model for RFI and to select animals with superior feed efficiency for improving Hanwoo cattle production.

Comparative Analysis of Skeletal Muscle Satellite Cells from Hanwoo Steers and Cows for Optimizing Cell-Based Meat Production

Comparative Analysis of Skeletal Muscle Satellite Cells from Hanwoo Steers and Cows for Optimizing Cell-Based Meat Production

Molecular signatures diversity unveiled through a comparative transcriptome analysis of longissimus dorsi and psoas major muscles in Hanwoo cattle

This study investigates the transcriptome-level alterations that influence production traits and early fattening stage myogenesis in Hanwoo cattle, specifically focusing on the highly prized Longissimus dorsi (LD) and Psoas major (PM) skeletal muscles, which hold significant commercial value. We conducted RNA sequencing analysis on LD and PM muscles from 14 Hanwoo steers (n = 7, each group) at the age of 10 months, all fed the same diet. Our results unveiled a total of 374 and 206 up-regulated differentially expressed genes (DEGs) in LD and PM muscles, respectively, with statistical significance (p < 0.05) and a log2fold change ≥ 1. Genes governing muscle development processes, such as PAX3, MYL3, COL11A1, and MYL6B, were found to be expressed at higher levels in both tissues. Conversely, genes regulating lipid metabolism, including FABP3, FABP4, LEP, ADIPOQ, and PLIN1, exhibited higher expression in the PM muscle. Functional enrichment analysis revealed a tissue-specific response, as PM muscle showed increased lipid metabolism allied pathways, including the PPAR signaling pathway and regulation of lipolysis in adipocytes, while LD was characterized by growth and proliferative processes. Our findings validate the presence of a muscle-dependent transcription and co-expression pattern that elucidates the transcriptional landscape of bovine skeletal muscle.

Correlation Analysis of Carcass Characteristics Factors According to Concentrate Diet and TMR Diet Feeding in Hanwoo Steers

Correlation Analysis of Carcass Characteristics Factors According to Concentrate Diet and TMR Diet Feeding in Hanwoo Steers

한우 거세우의 도체형질 및 생산비를 고려한 최적 출하월령 추정

한우 거세우의 도체형질 및 생산비를 고려한 최적 출하월령 추정

Effect of a Simultaneous Increase in Crude Protein and Total Digestible Nutrients Contents on Late Fattening Hanwoo Steers

Background: Shortening the fattening period can reduce production costs and inedible fat, but may simultaneously negatively affect productivity and profitability. We hypothesized that increasing the crude protein and total digestible nutrients (TDN) in the formula feed could address the issues associated with shortened fattening periods without adversely affecting rumen fermentation. This study investigated the effect of a simultaneous increase of crude protein and TDN contents compared to conventional formula feed on growth performance, blood metabolites, carcass characteristics and meat composition of late fattening Hanwoo steers. Methods: Thirty Hanwoo steers were randomly assigned to one of two dietary groups: control group (16.4% crude protein and 83.6% TDN based on dry matter) and treatment group (17.4% crude protein and 84.6% TDN based on dry matter). Result: The rumen parameters were similar between the control and treatment groups. Likewise, the effect of additional crude protein and TDN contents in the formula feed showed no significant impact on the growth performance or blood metabolites. The carcass weight and yield index were slightly higher in the treatment group compared to the control, yet these differences were not statistically significant. Furthermore, the dietary treatment did not affect marbling score, meat color, fat color, texture, maturity, pH, surface colors, drip loss, cooking loss, sensory characteristics, or fatty acid composition in the longissimus muscle.

Repeatability of feed efficiency and its relationship with carcass traits in Hanwoo steers during their entire growing and fattening period.

This study investigated the repeatability of feed efficiency and its association with carcass traits in Hanwoo steers during the entire growing and fattening periods. The growth and intake of thirty-six Hanwoo steers (259±19.7 kg; nine months) were monitored throughout five periods, including two growing periods (GP) and three fattening periods (FP). The steers were fed two types of concentrate mixes with varying nutrient compositions until they reached a target weight of 800 kg for slaughter. For each period, steers were categorized into three classes based on their feed efficiency rankings using residual feed intake (RFI) and feed conversion ratio (FCR). Feed efficiency repeatability was assessed using the Spearman correlation coefficient, decomposition of random errors, and the Theil segregation index (TSI). The Pearson correlation coefficient was used to examine the relationship between feed efficiency and carcass traits. The results demonstrated a significant and high correlation with RFI, but not FCR, during the growing or fattening stages (r>0.5; p<0.01). When steers were classified according to their feed efficiency rankings, 58% of the animals in the high RFI class (low efficient) initially (GP 1) remained in the same class by the last period (FP 3), whereas steers were randomly distributed based on FCR. The repeatability, assessed by the decomposition of random errors, was higher for RFI (0.61) than for FCR (0.15). The TSI also indicated that RFI rankings, rather than FCR rankings, are more likely to be maintained. Moreover, a weak association was observed between feed efficiency and carcass traits. In conclusion, RFI repeatability throughout the GP and FP surpassed that of the FCR, with steers classified as high RFI during the GP more likely to remain in the same class during the FP. Feed efficiency was weakly correlated with carcass traits.

Dietary effects of protected fat, glycerol, and soybean meal on performance, physiological parameters, carcass characteristics, and behavioral measurements of late-fattening Hanwoo steers under heat stress conditions.

This study aimed to determine the effects of increasing energy and protein levels in diets by including protected fat (PF), glycerol (GL), and soybean meal (SBM) on growth performance, physiological parameters, carcass characteristics, and behavioral measurements of late-fattening Hanwoo steers under heat stress conditions. Thirty-six steers (initial body weight, 724.9±58.3 kg; age, 25.5±0.4 month) were assigned into control (total digestible nutrient [TDN] 76%, crude protein [CP] 15%), PF (TDN 83.6%, CP 15%), PF+GL (TDN 83.6%, CP 15%) and PF+GL+SBM (TDN 83.6%, CP 16.5%) by randomized complete block design for a total of 16 weeks with division of 4-week periods. The average temperature-humidity index was 87.0 (1st period; severe), 82.8 (2nd; moderate), 71.4 (3rd; comfort), and 68.1 (4th; comfort). The dry matter intake (DMI) showed no treatments differences during the whole experiment. However, DMI in 1st and 2nd period decreased by approximately 30% and 10% compared to 4th period, respectively. Higher average daily gain and feed conversion ratio were noted for treatments compared to control at both 1st and 2nd period (p<0.05). There were no treatment effects on rectal temperature (RT), cortisol, and behaviors during the entire experiment. However, both RT and cortisol in 0, 1st and 2nd period were higher than those of 3rd and 4th period (p<0.05). Carcass yield and grade remained unaffected by increasing TDN and CP levels. Behavioral changes in the hot season (1st period) included reduced lying (43%), increased standing (48%), decreased walking (62%), and decreased eating (38%) (p<0.05), with an increase in drinking by 54%. Rumination during standing was 53% higher, while rumination during lying was about 33% lower compared to the post-hot season (3rd period) (p<0.05). Dietary supplementation of protected fat in late-fattening Hanwoo steers under heat stress had a positive effect on preventing a reduction in performance.

Impact of rumen cannulation surgery on rumen microbiota composition in Hanwoo steers.

Rumen cannulation is a surgical technique used to collect rumen contents from ruminants. However, rumen cannulation surgery may potentially impact the composition of the rumen microbiota. This study aimed to examine the longitudinal alterations in the rumen microbiota composition of Hanwoo steers after cannulation surgery. In this study, eight Hanwoo steers were used; four steers underwent rumen cannulation surgery (cannulation group), while the remaining four were left intact (control group). Rumen samples were collected from all eight steers using the stomach tubing method on the day before surgery (day 0) and on postoperative days 1, 4, 7, 10, 14, 17, 21, 24, and 28, resulting in 80 samples (10 timepoints × 8 animals). The microbiota of all 80 samples were analyzed using 16S rRNA gene amplicon sequencing with Quantitative Insights into Microbial Ecology version 2 (QIIME2). There were no significant differences (p > 0.05) in all major phyla and most major genera representing at least 0.5% of total sequences across all 80 samples between the control and cannulation groups on the preoperative and postoperative days. However, while the alpha diversity indices did not differ (p > 0.05) between the two groups on the preoperative day, they significantly differed (p < 0.05) between the two groups on the postoperative days. Further, the overall microbial distribution based on both unweighted and weighted principal coordinate analysis plots significantly differed (p < 0.05) between the two groups on both the preoperative and postoperative days. Orthogonal polynomial contrasts indicated that major genera and microbial diversity in the cannulation group decreased following surgery but returned to their initial states by postoperative day 28. In conclusion, this study demonstrates that rumen cannulation surgery affects some major taxa and microbial diversity, suggesting that the rumen cannulation method can alter the composition of rumen microbiota in Hanwoo steers.

Effects of Dietary Crude Protein Level of Concentrate Mix on Growth Performance, Rumen Characteristics, Blood Metabolites, and Methane Emissions in Fattening Hanwoo Steers

This study aimed to investigate the effect of varying levels of dietary crude protein (CP) on growth performance, rumen characteristics, blood metabolites, and methane emissions in fattening Hanwoo steers. Twenty-four steers, weighing 504 ± 33.0 kg (16 months old), were assigned to four dietary treatments with different CP concentrations (15, 18, 19, and 21% of CP on a dry matter (DM) basis). A linear increasing trend in the average daily gain (ADG) was observed (p = 0.066). With increased dietary CP levels, the rumen ammonia concentration significantly increased (p &lt; 0.001), while the propionate proportion linearly decreased (p = 0.004) and the proportions of butyrate and valerate linearly increased (p ≤ 0.003). The blood urea exhibited a linear increase (p &lt; 0.001), whereas the blood non-esterified fatty acids and cholesterol showed a linear decrease (p ≤ 0.003) with increasing dietary CP. The methane concentration from eructation per intake (ppm/kg), forage neutral detergent fiber (NDF) intake, total NDF intake, and ADG exhibited linear decreases (p ≤ 0.014) across the treatments. In conclusion, increasing the dietary CP up to 21% in concentrates demonstrated a tendency to linearly increase the ADG and significantly decrease the propionate while increasing the butyrate. The methane concentration from eructation exhibited a tendency to linearly decrease with increasing dietary CP.

Effect of Lupin Supplementation on the Growth, Carcass, and Meat Characteristics of Late-Fattening Hanwoo Steers.

This study aimed to investigate the effects of lupin flake supplementation on the growth, plasma parameters, carcass characteristics, and meat composition of late-fattening Hanwoo steers. The steers (n = 40) were randomly divided into the four groups with 10 steers each: LP0 (lupin flake 0%), LP3 (lupin flake 3%), LP6 (lupin flake 6%), and LP9 (lupin flake 9%). The total digestible nutriant intake increased as the concentration of lupin increased (linear and quadratic effects; p < 0.05). The thiobarbituric acid-reactive substance content in the strip loins decreased as lupin flake supplementation levels increased (linear and quadratic effects; p < 0.05), while carnosine levels increased linearly (p < 0.05). As the lupin flake supplementation level increased, anserine and creatinine contents increased linearly and quadratically (p < 0.05). Similarly, adenosine triphosphate (ATP) and adenosine monophosphate (AMP) content increased with increasing lupin flake supplementation levels in linear and quadratic effects (p < 0.001). Palmitoleic acid content increased significantly with increasing lupin flake supplementation level (linear and quadratic effects; p < 0.05). The content of oleic acid in the strip loin was not significant, but the unsaturated fatty acid (UFA) (p < 0.05) and n-6/n-3 ratio (p < 0.05) increased. The results of this study indicated that although lupin flake supplementation did not markedly affect the growth, carcass characteristics, or meat composition of late-fattening Hanwoo steers, it exerted a positive effect on the flavor, taste profiles (anserine, creatinine, ATP, and AMP), hypotonicity (TBARS), and healthy meat production (UFA and n-6/n-3 ratio) related to beef.

Effect of sodium formate and lactic acid bacteria treated rye silage on methane yield and energy balance in Hanwoo steers.

This study was performed to evaluate the effects of rye silage treated with sodium formate (Na-Fa) and lactic acid bacteria (LAB) inoculants on the ruminal fermentation characteristics, methane yield and energy balance in Hanwoo steers. Forage rye was harvested in May 2019 and ensiled without additives (control) or with either a LAB inoculant or Na-Fa. The LAB (Lactobacillus plantarum) were inoculated at 1.5 × 1010 CFU/g fresh matter, and the inoculant was sprayed onto the forage rye during wrapping at a rate of 4 L/ton of fresh rye forage. Sixteen percent of the Na-Fa solution was sprayed at a rate of approximately 6.6 L/ton. Hanwoo steers (body weight 275 ± 8.4 kg (n = 3, group 1); average body weight 360 ± 32.1 kg (n = 3, group 2)) were allocated into two pens equipped with individual feeding gates and used in duplicated 3 × 3 Latin square design. The experimental diet was fed twice daily (09:00 and 18:00) during the experimental period. Each period comprised 10 days for adaptation to the pen and 9 days for measurements in a direct respiratory chamber. The body weights of the steers were measured at the beginning and at the end of the experiment. Feces and urine were collected for 5 days after 1 day of adaptation to the chamber, methane production was measured for 2 days, and ruminal fluid was collected on the final day. In the LAB group, the ratio of acetic acid in the rumen fluid was significantly lower (p = 0.044) and the ratio of propionic acid in the rumen fluid was significantly higher (p = 0.017). Methane production per DDMI of the Na-FA treatment group was lower than that of the other groups (p = 0.052), and methane production per DNDFI of the LAB treatment group was higher than that of the other groups (p = 0.056). The use of an acid-based additive in silage production has a positive effect on net energy and has the potential to reduce enteric methane emissions in ruminants.

Effects of γ-aminobutyric Acids Supplementation on Growth Performance, Blood Profile and Carcass Characteristics of Fattening Hanwoo Steers

Effects of γ-aminobutyric Acids Supplementation on Growth Performance, Blood Profile and Carcass Characteristics of Fattening Hanwoo Steers

Effect of the Meal Interval Setting of an Automated Concentrate Feeding System on Feed Intake and Feeding Behavior in Fattening Hanwoo Steers.

An automatic concentrate feeding system (ACFS) divides the day into several intervals, allowing cattle to consume a predetermined amount of concentrate mix per interval. This study investigated the impact of changing these intervals (four vs. six) in an ACFS on its precision in monitoring the feed intake and feeding behavior of fattening Hanwoo steers. The experiment, involving 29 fattening Hanwoo steers (688 ± 43.3 kg of body weight, 24 months old), employed a switchback design with two interval settings: four and six per day. Both individual forage and concentrate intakes and feeding behaviors were automatically recorded; however, the ACFS measured feed supply, not actual intake. The precision of the ACFS's intake recordings was tested by manually assessing feed residuals per visit using video recordings. Although no difference was observed in the concentrate intake (p > 0.05), the six-interval setting reduced concentrate residuals by 0.2 kg per visit (p < 0.05). The increased interval setting also resulted in fewer visits for forage consumption and decreased forage and total dry matter intakes (p < 0.05). In conclusion, the increased interval setting for the ACFS reduced the visit frequency for forage consumption and actual forage consumption while improving the precision of the ACFS's intake recordings.

Effect of Supplementation with Amino acid Additives Containing with Protected Vtamin C or Detoxified Sulfur on Blood Metabolites and Meat Quality in Late-fattening Hanwoo steers in a High-temperature Stress Environment

Effect of Supplementation with Amino acid Additives Containing with Protected Vtamin C or Detoxified Sulfur on Blood Metabolites and Meat Quality in Late-fattening Hanwoo steers in a High-temperature Stress Environment

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.