Angus-sired Steers Research Articles

The impact of sire breed on feedlot performance and carcass characteristics of beef × Holstein steers.

Dairy herds are mating a portion of cows to beef cattle semen to create a value-added calf. Objectives of this study were to compare the feedlot performance and carcass characteristics of beef × Holstein steers by breed when sires represented bulls with commercially available semen. Three groups of single-born, male calves (n = 262) born to Holstein dams on 10 Pennsylvania dairies were sourced during 3 yr. Steers were sired by seven beef breeds: Angus, Charolais, Limousin, Hereford, Red Angus, Simmental, and Wagyu. Steers were picked up within a week of age and raised at two preweaned calf facilities until weaning (8 ± 1wk of age) under similar health and management protocols. Steers were then transported to a commercial calf growing facility where they were managed as a single group until 10 ± 2 mo of age when they were moved to be finished at the Pennsylvania Department of Agriculture's Livestock Evaluation Center feedlot. Groups of steers were selected for slaughter based on body weight. Carcass characteristics were evaluated by trained personnel and a three-rib section of the longissimus muscle (LM) was collected from each carcass for Warner-Bratzler shear force (WBSF) evaluation and intramuscular fat determination. Steers sired by all sire breeds except for Limousin had greater average daily gain (ADG; 1.62 to 1.76kg/d) than Wagyu × Holstein steers (1.39kg/d; P < 0.05). Angus-sired steers had an 8.6% greater ADG than Red Angus-sired steers (P < 0.05). Angus, Charolais (1.73kg/d), and Simmental-sired steers (1.68kg/d) also had greater ADG than Limousin-sired steers (1.55kg/d; P < 0.05). Wagyu × Holstein steers spent 5 to 26 more days on feed (P < 0.05) than Limousin × Holstein, Simmental × Holstein, Angus × Holstein, and Charolais × Holstein steers. Angus and Charolais-sired steers were also on feed for 19 and 21 d fewer, respectively, than Limousin-sired steers (P < 0.05). Red Angus-sired steers had greater marbling scores than Simmental and Limousin-sired steers and Angus and Charolais-sired steers had greater marbling scores than Limousin-sired steers (P < 0.05). Angus, Limousin, and Hereford-sired steers produced the most tender LM as evaluated by WBSF; Angus-sired carcasses (3.82kg) were more tender than Charolais (4.30kg) and Simmental-sired carcasses (4.51kg; P < 0.05). Limousin and Hereford-sired steers (3.70 and 3.83kg, respectively) also had more tender steaks than Simmental-sired steers.

41 Growth Performance and Carcass Characteristics of Beef-Sired Steers Born to Holstein Dams

Abstract The objective of this study was to compare feedlot growth performance and carcass characteristics of F1 beef × Holstein steers (n = 124) sired by commercially available Angus (n = 19 from 7 sires), Charolais (n = 79 from 3 sires), SimAngus (n = 16 from 3 sires), or Wagyu (n = 10 from 2 sires) bulls. Male calves born from May to August of 2021, were sourced from 8 Pennsylvania dairy herds. Steers were raised by a commercial calf grower until April of 2021 (10.5 ± 1.5 months of age). Steers were then moved to the PA Department of Agriculture’s Livestock Evaluation Center (LEC) and transitioned to a high-energy ration. Individual feed intake was monitored using the GrowSafe Feed Intake Monitoring System (Model 4000E, Vytelle, Calgary AB, Canada). Steers were slaughtered after 90, 118, or 153 days on feed at the LEC. Pulls were based on a combination of visual appraisal and body weight. Linear models of growth performance traits and carcass characteristics included the fixed effects of sire breed, herd of origin, and birthdate. Binomial models of USDA Quality Grades and Yield Grades included a fixed effect of sire breed. Angus-sired steers were heaviest at feedlot entry (P &amp;lt; 0.01) and were on feed for the fewest days (P &amp;lt; 0.01). Angus × Holstein steers were heavier at slaughter (P &amp;lt; 0.01) than SimAngus and Wagyu-sired steers. Wagyu-sired steers had the least dry matter intake (DMI), average daily gain (ADG), and carcass ADG (P &amp;lt; 0.01) when compared with progeny of other sire breeds. No differences in gain to feed intake (G:F(; P = 0.90), back-calculated carcass G:F (P = 0.62), net energy of metabolism (P = 0.70) and net energy of gain (P = 0.70), nor hip height at harvest (P = 0.14) were detected between sire breeds. Wagyu × Holstein carcasses were the lightest (P &amp;lt; 0.01) and had the least amount of backfat (P = 0.01). Dressing percentage tended to be least (P = 0.10) in Charolais × Holstein carcasses (60.5%) and greatest in SimAngus × Holstein carcasses (61.7%); carcasses from Angus and Wagyu-sired steers were intermediate and not different. About 84% of Angus × Holstein carcasses graded Choice while only 31% of SimAngus × Holstein carcasses graded Choice (P = 0.03). However, there were no differences in called marbling scores between sire breeds (P = 0.15). Charolais × Holstein tended to have the lowest proportion (4%) of Yield Grade 1 carcasses (P = 0.05). Angus-sired steers were on feed for the fewest days when compared with steers sired by other beef breeds. Wagyu × Holstein steers had reduced ADG, DMI, and subsequent carcass weight in comparison with compared steers of other sire breeds.

Lipid metabolism mRNA expression and cellularity of intramuscular adipocytes within the Longissimus muscle of Angus- and Wagyu-sired cattle fed for a similar days on feed or body weight endpoint

This study investigates intramuscular (IM) adipocyte development in the Longissimus muscle (LM) between Wagyu- and Angus-sired steers compared at a similar age and days on feed (D) endpoint or similar body weight (B) endpoint by measuring IM adipocyte cell area and lipid metabolism mRNA expression. Angus-sired steers (AN, n = 6) were compared with steers from two different Wagyu sires (WA), selected for either growth (G) or marbling (M), to be compared at a similar days on feed (DOF; 258 ± 26.7 d; WA-GD, n = 5 and WA-MD, n = 5) in Exp. 1 or body weight (BW; 613 ± 18.0 kg; WA-GB, n = 4 and WA-MB, n = 5) in Exp. 2, respectively. In Exp. 1, WA-MD steers had a greater (P ≤ 0.01) percentage of IM fat in the LM compared with AN and WA-GD steers. In Exp. 2, WA-MB steers had a greater (P ≤ 0.01) percentage of IM fat in the LM compared with AN and WA-GB steers. The distribution of IM adipocyte area was unimodal at all biopsy collections, with IM adipocyte area becoming progressively larger as cattle age (P ≤ 0.01) and BW increased (P ≤ 0.01). Peroxisome proliferator activated receptor delta (PPARd) was upregulated earlier for WA-MD and WA-MB cattle compared with other steers at a similar DOF and BW (P ≤ 0.02; treatment × biopsy interaction). Peroxisome proliferator activated receptor gamma was upregulated (PPARg) at a lesser BW for WA-MB steers (P = 0.09; treatment × biopsy interaction), while WA-MD steers had a greater (P ≤ 0.04) overall mean PPARg mRNA expression compared with other steers. Glycerol-3-phosphate acyltransferase, lipin 1, and hormone sensitive lipase demonstrated mRNA expression patterns similar to PPARg and PPARd or CCAAT enhancer binding protein beta, which emphasizes their importance in marbling development and growth. Additionally, WA-MD and WA-MB steers often had a greater early mRNA expression of fatty acid transporters (fatty acid transport protein 1; P < 0.02; treatment × biopsy interaction) and binding proteins (fatty acid binding protein 4) compared with other steers. Cattle with a greater marbling propensity appear to upregulate adipogenesis at a younger chronological and physiological maturity through PPARd, PPARg, and possibly adipogenic regulating compounds, lysophosphatidic acid, and diacylglycerol. These genes and compounds could be used as potential markers for marbling propensity of cattle in the future.

Growth performance, carcass characteristics, and fatty acid composition of Angus- and Wagyu-sired finishing cattle fed for a similar days on feed or body weight endpoint.

This study evaluated the feedlot performance, carcass characteristics, and fatty acid (FA) composition of Wagyu-sired and Angus-sired cattle at a similar days on feed (D) or body weight (B) endpoint. Wagyu-sired steers and heifers (WA) from two different sires, selected for either growth (G) or marbling (M), were compared with Angus-sired steers (AN, n = 13) in two independent incomplete-block design experiments at a similar days on feed (DOF; WA-GD, n = 9; WA-MD, n = 12) in experiment 1 or similar final body weight (BW; WA-GB, n = 9; WA-MB, n = 13) in experiment 2. Cattle were offered a corn silage-based growing diet for 119 d before being transitioned over 3 wk to a finishing diet. Data were analyzed as a randomized incomplete block design. In experiment 1, AN and WA-GD cattle had a greater (P < 0.01) off-test BW and average daily gain (ADGP < 0.04) than WA-MD cattle and AN had a greater dry matter intake (DMI; P < 0.02) than WA-GD and WA-MD cattle. The AN and WA-GD cattle had a greater carcass weight (P < 0.02) than WA-MD cattle. Percent kidney, pelvic, and heart fat (KPH) was greatest (P < 0.01) for WA-MD cattle, followed by WA-GD cattle, and lastly AN cattle. Total lipid (P < 0.03) and polyunsaturated FA (PUFA; P < 0.01) percentage were greater for WA-MD-cattle than AN and WA-GD cattle, as they tended (P = 0.11) to have the greatest 12th rib marbling score. In experiment 2, AN-cattle needed fewer (P < 0.01) DOF and had a greater (P ≤ 0.02) ADG, DMI, and gain:feed than WA-GB- and WA-MB-cattle. The WA-MB-cattle had a greater (P < 0.01) 12th and 6th rib marbling score, USDA quality grade, and 6th rib backfat thickness than AN-cattle. Compared with AN cattle, WA-GB cattle had a greater (P ≤ 0.01) percent KPH and lesser (P ≤ 0.03) rib thickness. The WA-MB-cattle had a greater (P ≤ 0.01) concentration of total lipid and PUFA than AN- and WA-GB-cattle, and lesser saturated FA (SFA; P < 0.01) concentration than AN-cattle in the longissimus muscle (LM). The 6th rib location of the LM had a greater (P ≤ 0.01) percentage of total lipid and SFA, but less (P < 0.03) MUFA compared with the 12th rib location. In conclusion, Wagyu-sired cattle selected for marbling potential had a lesser ADG, DMI, more marbling, more PUFA, and less SFA in the LM than Angus-sired cattle regardless of slaughter endpoint. Wagyu-sired cattle selected for growth potential had a similar ADG and carcass characteristics compared with Angus-sired cattle when fed for a similar number of days on feed.

Anabolic Implants Varying in Hormone Type and Concentration Influence Performance, Feeding Behavior, Carcass Characteristics, Plasma Trace Mineral Concentrations, and Liver Trace Mineral Concentrations of Angus Sired Steers.

Simple SummaryThough anabolic implants are commonly utilized in U.S. cattle production, comparisons between hormone type and content of different implants and the effects on growth and trace mineral stores is limited. The objective of this study was to evaluate the effects of anabolic implants varying in hormone type and concentration on growth, carcass characteristics, and trace mineral concentrations in Angus steers. Cattle administered an estradiol only implant did not experience differences in growth compared to non-implanted controls. However, cattle implanted with a trenbolone acetate only implant or a combined (estradiol and trenbolone acetate) implant experienced improvements in growth and changes in plasma and liver trace mineral concentrations. Greatest differences in growth and trace mineral concentrations were observed in steers administered the combination implant compared to non-implanted controls. These data suggest hormone type and concentration influence implant-induced growth and changes in plasma and liver trace mineral concentrations.Fifty Angus-sired steers were utilized to evaluate the effects of anabolic implants varying in hormone type and concentration on performance, carcass traits, and plasma and liver trace mineral concentrations over 129 d. Steers were stratified by weight into one of four (n = 12 or 13/treatment) implant treatments: (1) estradiol (E2; 25.7 mg E2; Compudose, Elanco Animal Health, Greenfield, IN, USA), (2) trenbolone acetate (TBA; 200 mg TBA; Finaplix-H, Merck Animal Health, Madison, NJ, USA), (3) combination implant (ETBA; 120 mg TBA + 24 mg E2; Revalor-S, Merck Animal Health), or (4) no implant (CON). Steers were randomly assigned to pens equipped with GrowSafe bunks and fed a corn and barley-based finishing ration. Overall average daily gain and body weight were greater for ETBA and TBA than CON (p ≤ 0.04), but not E2 (p ≥ 0.12). Feed efficiency and hot carcass weight were only greater than CON for ETBA (p ≤ 0.03). Plasma and d 2 liver Zn concentrations were lesser for ETBA than CON (p ≤ 0.01) and d 10 liver Mn was lesser (p = 0.0003) for TBA than CON. These data indicate that implants containing TBA influence growth and trace mineral parameters, though more work investigating this relationship is necessary.

Relationships between inflammation- and immunity-related transcript abundance in the rumen and jejunum of beef steers with divergent average daily gain.

The bovine rumen papillae are in contact with a wide array of microorganisms and the metabolites they produce, which may activate an inflammatory and/or immune response. Cytokines, chemokines and their receptor genes were tested for differential expression in the rumen and jejunum of beef steers with greater and lesser average daily body weight gain (ADG) near the average daily dry matter intake (DMI) for the population. Angus-sired steers (n=16) were used to represent the greater (ADG=2.2±0.07kg/day; DMI=10.1± 0.05kg/day) and lesser (ADG=1.7±0.05kg/day; DMI=10.1±0.05kg/day) ADG groups with eight steers each. Rumen epithelium and jejunum mucosal samples were collected at slaughter, and gene expression was evaluated using a commercially available qRT-PCR array containing 84 genes representing chemokines, cytokines and their receptors. None of the genes on the array were differentially expressed in the jejunum of the steers with greater vs. lesser ADG. However, in the rumen, two chemokine genes (CCL11, CXCL5) and one receptor gene (IL10RA) were detected as differentially expressed (P<0.05). The genes IL1A, BMP2, CXCL12 and TNFSF13 also displayed trends for differential expression (P<0.10). All of the genes identified were lower in transcript abundance in the greater ADG animals. Thus, greater ADG steers have a lesser inflammatory response in the rumen papillae, which may lead to a more efficient use of nutrients.

Endocannabinoids concentrations in plasma associated with feed efficiency and carcass composition of beef steers.

Endocannabinoids, including anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are a class of endogenous lipid mediators that activate cannabinoids receptors and may be involved in the control of feed intake and energy metabolism. The objective of this study was to quantify AEA and 2-AG in plasma and identify possible associations with production traits and carcass composition in finishing beef steers. Individual DMI and BW gain were measured on 140 Angus-sired steers for 105 d on a finishing ration. Blood samples were collected on d 84 of the experiment, which was 40 d before slaughter. Variables were analyzed using Pearson CORR procedure of SAS. Mean endocannabinoid concentrations in plasma were 4.48 ± 1.82 ng/mL and 0.44 ± 0.24 ng/mL for AEA and 2-AG, respectively. The AEA concentration was positively correlated with G:F ratio ( = 0.20; = 0.02), indicating that more efficient animals had greater AEA plasma concentrations. In addition, AEA concentration tended to be negatively correlated with the 12th rib fat thickness ( = -0.17; = 0.07); but no correlation was found with USDA-calculated yield grade ( = -0.14; = 0.11), or marbling score ( = 0.05; = 0.54). The concentration of 2-AG was positively correlated with AEA ( = 0.21; = 0.01); however, 2-AG concentration was not correlated with parameters of feed efficiency or carcass composition. To our knowledge, this study is the first to report plasma concentration of endocannabinoids in steers. These results provide evidence that plasma concentration of a key endocannabinoid, AEA, was favorably correlated with feed efficiency and fat thickness in finishing steers.

Intake of milk and pasture and growth rate of calves reared by cows with high or low potential for milk production

Milk production of cows influences calf weaning weight, which is the major driver for economic return in a cow–calf operation. The growth trajectory of 64 steer calves resulting from a terminal cross between Angus or Simmental bulls with Angus, Angus cross Holstein Friesian, Angus cross Jersey and Angus cross KiwiCross cows was examined during the pre-weaning period from birth (D0) to weaning (D148) and during the post-weaning period until a year of age (D365). Random regression models were used to model milk intake and liveweight of calves throughout lactation. These models were a good fit to the data (r2 = 0.77 for milk intake and r2 = 0.99 for liveweight). Total energy intake from milk was greater (P &lt; 0.05) for the Angus cross Holstein Friesian-, Angus cross Jersey- and Angus cross KiwiCross-reared steers than for those reared by Angus dams. Additional milk intake increased liveweight of steers from D90 to D365, but the magnitude of the effect decreased as the calves aged. Simmental-sired steers had a greater liveweight response to additional milk intake than Angus-sired steers at D120 and D148, probably reflecting greater growth potential from out-crossed calves.

Evaluation of implant strategies in Angus-sired steers with high or low genetic potential for marbling and gain1

Sixty-nine Angus-sired steer calves (332.3 kg initial BW) were used to determine the effects of single or double implant strategies on steers of high or low genetic potential (GP) determined by the GeneMax (Zoetis, Florham Park, NJ) genetic profiling test. Steers were assigned to treatments in a 2 × 2 factorial design with factors of 1) composite GP score (high, mean GP score of 86.5 [HI]; low, mean GP score of 25.3[LO]) and 2) implant strategy (single, steers implanted on d 70 [1X], or double, steers implanted d 0 and 70 [2X]). All steers were given the same implant (Revalor-S; Merck Animal Health, Summit, NJ), with the 2X group implanted on d 0 and 70 and the 1X group implanted only on d 70. A diet containing 1.38 Mcal NEg/kg DM was fed ad libitum, once daily. Ultrasound was used to measure body composition characteristics on d 0 and 70. Steers were harvested after 140 d on feed. At both the d-0 and d-70 ultrasound, HI steers had greater ( < 0.001) percent intramuscular fat (IMF) than LO steers, but no differences ( ≥ 0.24) were observed in LM area (LMA), rib fat thickness (RF), or rump fat thickness (RMFT). Steers in the 2X group had larger ( = 0.02) LMA and less ( = 0.03) IMF on d 70 than 1X steers and no differences ( ≥ 0.50) in RF or RMFT were observed. From d 0 to 70, HI steers had ADG, DMI, and G:F ( ≥ 0.60) similar to LO steers; however, 2X steers had greater ( < 0.001) ADG and were more ( < 0.001) feed efficient compared with 1X steers during the same interval. Over the entire 140-d feeding period, there were no differences ( ≥ 0.6) in BW, ADG, DMI, or G:F between GP groups; however, 2X steers had greater ( = 0.03) ADG compared with 1X steers and still had similar ( ≥ 0.12) DMI and G:F. Upon slaughter, marbling score tended to be impacted by a GP × implant interaction (499.9 ± 18.5, 545.6 ± 18.5, 487.1 ± 18.5, and 469.8 ± 18.5 for HI and 2X, HI and 1X, LO and 2X, and LO and 1X, respectively; = 0.06). No differences ( ≥ 0.7) were observed between GP groups for HCW, LMA, RF, KPH, or yield grade (YG). Steers in the 1X group had less ( = 0.003) RF than 2X steers but similar ( ≥ 0.14) HCW, marbling, LMA, KPH, and YG. A greater proportion ( = 0.03) of HI steers had choice carcasses (100 ± 0.0%) compared with LO steers (87.8 ± 3.9%). Results of this study indicate that the GP test used in the current study predicted differences in IMF, carcass marbling, and percent carcasses graded as choice.

Effect of residual feed intake on hypothalamic gene expression and meat quality in Angus-sired cattle grown during the hot season1,2

The relationship between heat stress, meat quality, and residual feed intake (RFI) is unknown in growing steers. To address this issue, high RFI (HRFI) and low RFI (LRFI) individuals were compared by assessing RFI in 48 Angus-sired steers during a 70-d feeding trial conducted during July through September to identify steers with calculated RFI at least 2 SD apart. The association of RFI with indices of meat quality and expression of genes within hypothalamic and adipose tissue was then determined in LRFI and HRFI steers. While on test, feed intake was recorded daily with BW and hip heights recorded every 14 d. Ultrasound measurements of rib eye area (REA) and backfat (BF) were recorded initially and before harvest. Carcass and growth data were analyzed using a mixed model with RFI level (LRFI and HRFI) as the independent variable. The least square means for RFI were -1.2 and 0.99 kg DMI/d, respectively, for the LRFI and HRFI cohorts (P < 0.0001). Dry matter intake was higher for the HRFI individuals versus the LRFI steers (P < 0.0001) while on-test gain was not different (P < 0.95). Marbling score was greater in LRFI than HRFI steers (P < 0.05). However, there were no differences in REA (P < 0.53), BF (P < 0.65), yield grade (P < 0.24), or objective Hunter color measures between LRFI and HRFI steers indicating there was no consistent relationship between RFI and indices of meat quality. Hypothalamic neuropeptide Y (NPY), agouti related protein (AGRP), relaxin-3 (RLN3), melanocortin 3 receptor, and relaxin/insulin-like family peptide receptor 1 (RXFP1) mRNA were expressed 280, 185, 202, 183, and 163% greater, respectively (P < 0.01), while proopiomelanocortin (POMC) mRNA was expressed 42% lower in LRFI than HRFI animals (P < 0.05). Hypothalamic GnRH mRNA expression was 67% lower while gonadotropin inhibiting hormone (GnIH) mRNA was 209% higher in LRFI than HRFI animals (P < 0.01). Pituitary expression of FSHβ and LHβ correlated to hypothalamic GnRH levels (P < 0.05) indicating changes in gene expression within the hypothalamus had functional consequences. Leptin mRNA expression levels were not different between adipose tissue of LRFI or HRFI steers (P < 0.84). These data indicate that animals with superior RFI evaluated during warm conditions have higher expression of orexigenic neuropeptide genes independent of the expression of adipose-derived leptin. Furthermore, the gonadotropin axis may also influence feed efficiency under these conditions.

Residual feed intake studies in Angus-sired cattle reveal a potential role for hypothalamic gene expression in regulating feed efficiency1,2

Mechanisms underlying variation in residual feed intake (RFI), a heritable feed efficiency measure, are poorly understood while the relationship between RFI and meat quality is uncertain. To address these issues, 2 divergent cohorts consisting of High (HRFI) and Low (LRFI) RFI individuals were created by assessing RFI in 48 Angus-sired steers during a 70 d feeding trial to identify steers with divergent RFI. The association of RFI with indices of meat quality and expression of genes within hypothalamic and adipose tissue was then determined in LRFI and HRFI steers. While on test, feed intake was recorded daily with BW and hip heights recorded at 14 d intervals. Ultrasound measurements of rib eye area (REA) and backfat (BF) were recorded initially and before harvest. Carcass and growth data were analyzed using a mixed model with RFI level (LRFI, HRFI) as the independent variable. The least-square means (lsmeans) for RFI were -1.25 and 1.51 for the LRFI and HRFI cohorts (P < .0001). Dry matter intake was higher for the HRFI individuals versus the LRFI steers (P < .0001) while on test BW gain was not different between the 2 groups (P < 0.73). There were no differences detected in marbling score (P < 0.93), BF (P < 0.61), REA (P < 0.15), yield grade (P < 0.85) or objective Hunter color measures between LRFI and HRFI steers indicating that there was no relationship between RFI and meat quality. Neuropeptide-Y (NPY), relaxin-3 (RLN3), melanocortin 4 receptor (MC4R), and GnRH mRNA expression was 64%, 59%, 58%, 86% lower (P < 0.05), respectively, while gonadotropin inhibiting hormone (GnIH) and pro-opiomelanocortin (POMC) mRNA expression was 198% and 350% higher (P < 0.01) in the arcuate nucleus of LRFI steers. Expression of agouti-related protein (AGRP), relaxin/insulin-like family peptide receptor 1 (RXFP1), and melanocortin 3 receptor mRNA was similar between LRFI and HRFI animals. Pituitary expression of FSHβ (P < 0.03) and LHβ (P < 0.01) was correlated to hypothalamic GnRH levels suggesting that changes in gene expression within the arcuate nucleus had functional consequences. Leptin mRNA expression was 245% higher in the adipose tissue of LRFI steers consistent with lower levels of NPY and higher expression of POMC in their hypothalami. These data support the hypothesis that differences in hypothalamic neuropeptide gene expression underlie variation in feed efficiency in steers while the gonadotropin axis may also influence feed efficiency.

Effect of muscle type, sire breed, and time of weaning on fatty acid composition of finishing steers1

Thirty-three steer calves were used to determine the effect of sire breed (Angus or Charolais), time of weaning [normal weaned at approximately 210 d of age (NW) or late weaned at approximately 300 d of age (LW)], and muscle type [LM and semitendinosus muscle (STN)] on fatty acid composition. The whole plot consisted of a 2 (sire breed) × 2 (time of weaning) treatment arrangement, and the subplot treatment was muscle type. Body weights were recorded at 28-d intervals to determine animal performance. Muscle biopsies were collected on d 127 and 128 of finishing. All calves were slaughtered on d 138, and carcass data were collected. Angus-sired steers had lighter initial BW (271 vs. 298 kg; P = 0.02), and LW steers were heavier (351 vs. 323 kg; P = 0.03) on d 28, but no other differences in BW were noted. Charolais-sired steers had larger LM area (P = 0.03), reduced yield grades (P = 0.01), less 12th-rib fat (P < 0.01), and less marbling (P < 0.01) than Angus-sired steers. Carcass measures overall indicate Angus-sired steers were fatter. Hot carcass weight was heavier (348 vs. 324 kg; P = 0.04) in LW steers than NW steers. No other differences (P > 0.05) were observed for feedlot performance or carcass characteristics. Total lipids were extracted from muscle biopsies, derivatized to their methyl esters, and analyzed using gas chromatography. The LM had greater SFA (43.94 vs. 35.76%; P < 0.01) and decreased unsaturated fatty acids (UFA; 56.90 vs. 66.19%; P < 0.01) compared with the STN. Percent total MUFA was greater in STN than LM (51.05 vs. 41.98%; P < 0.01). Total SFA, UFA, and MUFA did not differ due to sire breed or time of weaning. Total PUFA differed (P = 0.04) due to a sire breed × time of weaning interaction but did not differ due to muscle type, with greater PUFA in NW Charolais than any other sire breed × time of weaning combination. Observed changes in percent MUFA may be a result of greater Δ(9)-desaturase activity. The calculated desaturase index suggests STN has a greater Δ(9)-desaturase activity than LM, but no differences (P > 0.05) between sire breed or time of weaning were observed. These results indicate that sire breed, time of weaning, and muscle type all affect fatty acid composition in beef. This information provides insight into factors for manipulation of beef fatty acids. More research is needed to identify beef cuts based on fatty acid profile and healthfulness.

Effect of Wagyu- versus Angus-sired calves on feedlot performance, carcass characteristics, and tenderness

Wagyu-sired (n = 20) and Angus-sired (n = 19) steers and heifers were used to compare the effects of sire breed on feedlot performance, carcass characteristics, and meat tenderness. Calves were weaned at 138 +/- 5 d of age and individually fed a finishing diet consisting of 65% whole corn, 20% protein/vitamin/mineral supplement, and 15% corn silage on a DM basis. Heifers and steers were slaughtered at 535 and 560 kg of BW, respectively. Carcasses were ribbed between the 12th and 13th (USDA grading system) and the 6th and 7th ribs (Japanese grading system) to measure fat thickness, LM area (LMA), and intramuscular fat (IMF). Two steaks were removed from the 12th rib location and aged for 72 h and 14 d to determine Warner-Bratzler shear force and cooking loss. Sire breed x sex interactions were not significant (P > 0.05). Angus-sired calves had greater (P < 0.05) ADG and DMI than Wagyu. Wagyu-sired calves had improved (P < 0.05) feed efficiency than Angus. Sire breed did not affect (P > 0.20) HCW, 12th-rib fat, or USDA yield grade. Carcasses of Wagyu had greater (P = 0.0001) marbling scores at the 12th rib than those of Angus (770.9 vs. 597.3 +/- 41.01, respectively). Carcasses of Wagyu also had greater (P < 0.02) 12th-rib IMF and 6th-rib IMF than Angus, resulting in a greater proportion of carcasses grading Prime (65.0 vs. 21.1%; P = 0.006). Carcasses from Wagyu tended (P = 0.08) to have greater LMA at the 12th rib, whereas Angus carcasses had greater (P < 0.05) LMA at the 6th rib. Steaks from Angus and Wagyu had similar (P > 0.50) tenderness at aging times of 72 h and 14 d. Cooking loss was greater (P < 0.01) for Angus than Wagyu steaks at 72 h and 14 d. Using Wagyu sires vs. Angus sires on British-based commercial cows combined with early weaning management strategies has the potential to produce a product with greater marbling, but is unlikely to significantly enhance tenderness.

Genetic and phenotypic relationships of serum leptin concentration with performance, efficiency of gain, and carcass merit of feedlot cattle1

Leptin is the hormone product of the obese gene that is synthesized and predominantly expressed by adipocytes. This study estimated the genetic variation in serum leptin concentration and evaluated the genetic and phenotypic relationships of serum leptin concentration with performance, efficiency of gain, and carcass merit. There were 464 steers with records for serum leptin concentration, performance, and efficiency of gain and 381 steers with records for carcass traits. The analyses included a total of 813 steers, including those without phenotypic records. Phenotypic and genetic parameter estimates were obtained using SAS and ASREML, respectively. Serum leptin concentration was moderately heritable (h2 = 0.34 +/- 0.13) and averaged 13.91 (SD = 5.74) ng/mL. Sire breed differences in serum leptin concentration correlated well with breed differences in body composition. Specifically, the serum leptin concentration was 20% greater in Angus-sired steers compared with Charolais-sired steers (P < 0.001). Consequently, ultrasound backfat (27%), carcass 12th-rib fat (31%), ultrasound marbling (14%), and carcass marbling (15%) were less in Charolais- than Angus-sired steers (P < 0.001). Conversely, carcass LM area (P = 0.05) and carcass lean meat yield (P < 0.001) were greater in Charolais- compared with Angus-sired steers. Steers with greater serum leptin concentration also had greater DMI (P < 0.001), greater residual feed intake (P = 0.04), and partial efficiency of growth (P = 0.01), but did not differ in feed conversion ratio (P > 0.10). Serum leptin concentration was correlated phenotypically with ultrasound backfat (r = 0.41; P < 0.001), carcass 12th-rib fat (r = 0.42; P < 0.001), ultrasound marbling (r = 0.25; P < 0.01), carcass marbling (r = 0.28; P < 0.01), ultrasound LM area (r = -0.19; P < 0.01), carcass LM area (r = -0.17; P < 0.05), lean meat yield (r = -0.38; P < 0.001), and yield grade (r = 0.32; P < 0.001). The corresponding genetic correlations were generally greater than the phenotypic correlations and included ultrasound backfat (r = 0.76 +/- 0.19), carcass 12th-rib fat (r = 0.54 +/- 0.23), ultrasound marbling (r = 0.27 +/- 0.22), carcass marbling (r = 0.76 +/- 0.21), ultrasound LM area (r = -0.71 +/- 0.19), carcass LM area (r = -0.75 +/- 0.20), lean meat yield (r = -0.59 +/- 0.22), and yield grade (r = 0.39 +/- 0.26). Serum leptin concentration can be a valuable tool that can be incorporated into appropriate selection programs to favorably improve the carcass merit of cattle.

Performance and carcass quality of steers fed whole raw soybeans at increasing inclusion levels1

Two experiments were conducted to determine the efficacy of whole raw soybeans as a partial or whole replacement for soybean meal in a corn/soybean meal-based feedlot diet. In Exp. 1, 80 crossbred steers (average BW = 441.3 kg) and, in Exp. 2, 96 Angus-sired steers (average BW = 413.7 kg) were blocked by weight and assigned randomly to one of four dietary treatments. Treatments were 0, 8, 16, and 24% dietary inclusions of whole raw soybeans. Diets within experiments were isonitrogenous. Across experiments, diets were similar, differing only in amount of corn silage (8 vs. 15% DM) at the expense of whole, shelled corn for Exp. 1 and Exp. 2, respectively. No treatment differences were observed for ADG or final BW. Dry matter intake from d 0 to d 58 decreased linearly (P < 0.05) with increased inclusion of whole raw soybeans in Exp. 1, with no effect on feed efficiency. In Exp.2 from d 0 to 72, whole raw soybean inclusion had no effect on DMI or feed efficiency. There tended (P < 0.10) to be a linear reduction in hot carcass weight when whole raw soybeans were included in Exp. 1. Unexpectedly, longissimus muscle area tended (P < 0.10) to respond quadratically (P < 0.10) to the increased inclusion of whole raw soybeans in Exp.1. No differences were detected in marbling score, 10th-rib backfat, or yield grade for Exp. 1 and 2 steers. In Exp. 2, inclusion of whole raw soybeans had no effect on hot carcass weight or longissimus muscle area. Incrementally increasing the inclusion of whole raw soybeans in the diet of feedlot steers had little overall effect on weight gain, feed efficiency, or carcass quality in Exp. 1 and 2. There were subtle differences in the treatment responses observed for hot carcass weight and longissimus muscle area between Exp. 1 and Exp. 2 for the 24% inclusion level. These noted differences may indicate that inclusion levels above 24% might not be beneficial.

Heritability and correlation estimates of Warner-Bratzler shear force and marbling score from Angus-, Charolais-, Hereford-, and Simmental-sired cattle (2003)

The objective of this study was to estimate heritabilities and genetic correlations for Warner- Bratzler shear force and marbling score of longissimus steaks from Angus-, Charolais-, Hereford-, and Simmental-sired cattle in the National Cattlemen's Beef Association (NCBA) coordinated Carcass Merit Traits Project funded with Beef Checkoff dollars. There were 700 Angus-sired steers, 691 Charolais-sired steers and heifers, 938 Hereford-sired steers, and 1,167 Simmental-sired steers and heifers in the study. Restricted maximum likelihood estimates of the genetic parameters were determined using a sire model with a sire/maternal grandsire relationship matrix. The heritabilities for Warner-Bratzler shear force and marbling score, respectively, were 0.35 and 0.36 for Angus, 0.43 and 0.26 for Charolais, 0.12 and 0.59 for Hereford, and 0.13 and 0.42 for Simmental. The genetic and phenotypic correlations between Warner-Bratzler shear force and marbling score, respectively, were -0.19 and -0.18 for Angus; -0.36 and -0.19 for Charolais; - 0.47 and -0.23 for Hereford; and +0.64 and - 0.11 for Simmental. The high positive genetic correlation between Warner-Bratlzer shear force and marbling score for Simmental sires indicates that as marbling increased Warner- Bratzler shear force increased (decreased tenderness). These results suggest that selection for increased marbling in the Simmental breed would actually have a detrimental effect on tenderness. Selection for Warner-Bratzler hear force in Angus and Charolais could result in improved in tenderness, but little progress would be expected in Hereford sired cattle. In general, selection for marbling score in these breeds would improve tenderness only minimally.

Feedlot and Carcass Performance of Angus-, Brangus-, Gelbvieh-, and Gelbray-Sired Crossbred Steers11Approved for publication by the director of Louisiana Agric. Exp. Stn. as Manuscript No. 99-80-0342.

Feedlot and carcass traits were evaluated for steers (n = 231) sired by Angus (A), Brangus (BA), Gelbvieh (G), and Gelbray (GB) bulls (n = 29) out of first cross (F1) Brahman-Hereford cows. Steers were produced over 4 y and were born during spring and fall calving seasons. Brahman inheritance was 25% in A- and G-sired steers, and 44% in BA- and GB-sired steers. After weaning, steers were stockered before entering the feedlot. Steers produced in 1993 and 1994 were fed in Louisiana and individually harvested at a targeted backfat thickness of 10 mm. Steers born in 1995 and 1996 were fed in Oklahoma and group harvested at an average backfat thickness of 10 mm. Data were analyzed separately by feedlot location because of significant location and sire breed x location effects. Angus-sired steers had smaller (P<0.05) longissimus areas (LMA) and higher (P<0.01) marbling scores(MS) and quality grades than G-sired steers across both locations. Tenderness was more desirable (P<0.05) for A-sired steers compared with G-sired steers when fed in Louisiana. Angus- and G-sired steers had larger (P<0.01) LMA than BA- and GB-sired steers across both locations. Tenderness was similar (P>0.10) between steers with 25% and 44% Brahman inheritance. These data suggest that more desirable carcass quality and tenderness can be achieved with the use of A sires, relative to the other sire breeds, when mated to F1 Brahman-Hereford dams. Improved carcass cutability resulted with the use of G sires, and in steers with 25% Brahman inheritance.

Effects of supplemental zinc concentration and source on performance, carcass characteristics, and serum values in finishing beef steers.

Three studies were conducted to examine the effects of zinc concentration or source in diets of finishing beef steers. In Exp. 1, 108 (British x Continental) beef steers were supplemented with concentrations of added zinc (as ZnSO4) at 20, 100, or 200 mg/kg of dietary DM. No differences (P > 0.10) were noted among treatments for ADG or gain:feed for the 112-d finishing period. However, a linear (P < 0.10) decrease was noted in daily DMI with increasing zinc concentrations for the overall finishing period. No differences (P > 0.10) were noted in hot carcass weight; dressing percentage; longissimus muscle area; percentage of kidney, pelvic, and heart fat; or marbling score. There were, however, quadratic increases in s.c. fat thickness (P < 0.05) and yield grade (P < 0.01) with added zinc. In Exp. 2, 12 beef steers were used to examine effects of added dietary zinc on serum concentrations of cholesterol and fatty acid profiles. No differences (P > 0.10) were observed in cholesterol or fatty acids among the supplemental zinc levels. In Exp. 3, 84 Brangus- and Angus-sired steers were fed a steam-flaked corn-based diet containing 30 mg of supplemental zinc per kilogram of dietary DM from one of the following sources: 1) ZnSO4, 2) Zn amino acid complex, or 3) a zinc polysaccharide complex. No differences (P > 0.10) were noted for the overall 126-d trial for ADG, DMI, or gain:feed ratio. Percentage kidney, pelvic, and heart fat was increased (P < 0.10) in steers supplemented with ZnSO4 vs the average of Zn amino acid and Zn polysaccharide complexes. However, s.c. fat thickness was greater (P < 0.10) in steers supplemented with Zn amino acid and Zn polysaccharide complexes vs ZnSO4. Serum zinc concentration did not differ (P > 0.10) among zinc sources. Supplemental zinc concentration in finishing diets did not seem to influence feedlot performance and had a minimal impact on carcass quality. Either the organic or inorganic source can be included in finishing diets without affecting feedlot performance.

Effects of breed and sire on carcass characteristics and fatty acid profiles of crossbred wagyu and angus steers

In a two-year experiment, 54 steers sired by seven Wagyu bulls [American Wagyu Association (AWA) sire numbers 331, 384, 388, 411, 429, 433 and 488] and 15 steers sired by two Angus bulls, all out of Angus-Hereford cows, were used to evaluate the effects of sire and breed on carcass characteristics and fatty acid composition. Steers were given ad-libitum access to a high-concentrate diet (15 % alfalfa cubes and 85 % barley supplement) for at least 170 days. Breed and individual sire effects were analysed. Wagyu-sired steers had higher marbling, maturity and quality scores, more estimated kidney, pelvic and heart fat, larger longissimus dorsi muscle areas, lower fat thicknesses and yield grades than Angus-sired steers ( p < 0.05). Steers sired by 388, 411 and 433 had lower fat thicknesses than steers sired by Angus, 429 and 488 ( p < 0.05). Steers sired by 384 and 388 had higher marbling scores per cm subcutaneous fat than steers sired by Angus, 429 and 488, and lower fat thickness per 100 kg of carcass weight than Angus-sired steers ( p < 0.05). For both subcutaneous fat and longissimus dorsi muscle, Wagyu-sired steers had higher ( p < 0.05) percentages of 14:0, 14:1, 16:0, 16:1, and lower percentages of 18:0 than Angus-sired steers. The genetic differences in carcass characteristics among Wagyu sires may enable us to select for improved marbling with less fat in the Wagyu breed. Some statistically significant ( p < 0.05) but small differences existed in fatty acid profiles between breeds and among sires.

Biological type effects on postweaning growth, feed efficiency and carcass characteristics of steers.

Postweaning growth, feed consumption and carcass characteristics of 259 individually fed F1 Angus-, Red Poll-, Pinzgauer-, Simmental- and Tarentaise-sired steers from Hereford dams were compared. Average daily gain to 382 d of age for Simmental-sired steers exceeded (P less than .05) the ADG for Red Poll, Angus and Pinzgauer, which were not different. Tarentaise-sired steers were intermediate in growth rate. Simmental-sired steers required less (P less than .05) feed per kilogram of gain than Red Poll- and Angus-sired steers to reach either 382 d of age or 400 kg. Feed conversion (FC) by Simmental, Pinzgauer and Tarentaise-sired steers did not differ (P greater than .05), nor did FC by Red Poll- and Angus-sired steers to reach 382 d or 400 kg. Angus-sired steers required less ME per kilogram of gain to reach 12.7 mm of carcass backfat than did Red Poll-, Pinzgauer- or Tarentaise-sired steers, which were similar. Simmental-sired steers were intermediate in feed conversion to 12.7-mm fat depth and did not differ from the other breed groups. Rankings of breed groups for traits indicative of lean tissue growth were similar to rankings for live animal growth traits. At age- and weight-constant endpoints, Angus-sired steers had more (P less than .05) fat cover and marbling than did steers sired by the other breeds. At these endpoints, Red Poll-sired steers also had more (P less than .05) fat cover than did Pinzgauer-, Simmental- and Tarentaise-sired steers, which were similar.