Acyl-homoserine-lactone autoinducer in the gastrointestinal [corrected] tract of feedlot cattle and correlation to season, E. coli O157:H7 prevalence, and diet.

Acyl-homoserine-lactone autoinducer (AHL) produced by nonenterohemorrhagic Escherichia coli species in cattle appears to be required for enterohemorrhagic E. coli (EHEC) colonization of the gastrointestinal tract (GIT). The current research aimed to examine the effect of season, diet, EHEC shedding, and location within the GIT on AHL prevalence in the ruminant. Luminal content samples were collected from the rumen and rectum of feedlot cattle at slaughter in the spring, summer, fall, and winter for culture of E. coli O157:H7 and AHL determination. During the spring collection, samples were additionally collected from the cecum and small intestine, but these samples all were AHL negative and therefore not examined again. To assess the influence of diet on AHL prevalence, 14 lambs were fed either 100% forage or 80% concentrate diets and experimentally inoculated with EHEC. At 8 days after infection, all the lambs were killed, and necropsies were taken, with luminal contents collected from the GIT. The collections from the feedlot cattle had AHL in 100% of the rumen content samples from the spring, summer, and fall, but not in any of the winter samples. No other GIT samples from feedlot cattle were AHL positive, and all the samples from the sheep study were AHL negative. The cattle seemed to show a weak correlation between ruminal AHL and EHEC prevalence. This research found AHL only in the rumen and not in the lower GIT of feedlot cattle. However, it is unclear whether this is because the pH of the lower gut destroys the AHL or because a lack of certain bacteria in the lower gut producing AHL.

An exploratory observational study to develop an improved method for quantifying beef carcass salable meat yield.

Eighty-seven grain-finished steers were harvested, evaluated, and fabricated into wholesale cuts to determine what measured composition indicators most accurately describe the percentage of closely trimmed salable meat yield. Indicators of lean and fat composition present at the cross-section between the 12th and 13th ribs were objectively evaluated using Assess image analysis software. Salable meat yield ranged from 50.18% to 72.92%, trimmable fat yield ranged from 12.87% to 36.69%, and bone yield ranged from 10.07% to 19.21%. Regression models were developed to estimate percentage of total salable meat yield. Composition indicators chosen to predict salable meat yield included hot carcass weight (HCW), perinephric fat weight, longissimus muscle area (LMA), subcutaneous fat thickness (SFT), ratio of LMA to subcutaneous fat area, and ratio of subcutaneous fat depth to HCW. These results indicate that prediction of beef carcass salable meat yield can be improved via modification to current measures used in the USDA yield grade equation and addition of new measures.

Estimation of carcass composition using rib dissection of calf-fed Holstein steers supplemented zilpaterol hydrochloride.

A serial harvest was conducted every 28 d from 254 to 534 d on feed (DOF) to quantify changes in growth and composition of calf-fed Holstein steers (n = 115, initial body weight (BW) = 449.2 ± 19.9 kg). One-half were supplemented with the ß-2 adrenergic agonist zilpaterol hydrochloride (ZH; 8.33 mg/kg 100% dry matter (DM) basis) during the final 20 d followed by a 3-d withdrawal prior to harvest; the remainder was fed a non-ZH control (CON) ration. Five steers were randomly selected and harvested after 226 DOF which served as a reference point for modeling purposes. Fabricated carcass soft tissue was ground, mixed, and subsampled for proximate analysis. Moreover, following the traditional method of rib dissection which includes the 9th, 10th, and 11th rib contained within the IMPS 103 primal, the relationship of carcass chemical composition to 9-10-11 rib composition was evaluated. Carcasses in this investigation had more (P < 0.01) separable lean, fat, ash, and moisture concomitant with less bone and ether extract than rib dissections. However, protein levels were similar (P = 0.27) between carcasses and rib dissections. Using regression procedures, models were constructed to describe the relationship of rib dissection (RD) composition including separable lean (RDSL), separable fat (RDSF), separable bone (RDSB), ether extract (RDEE), protein (RDP), moisture (RDM), and ash (RDA) with carcass composition. Carcass lean (CL), carcass fat (CF), and carcass bone (CB) were correlated (P < 0.01) with RDSL, RDSF, and RDSB with simple r values of 0.41, 0.71, and 0.50, respectively. Chemical composition of the rib and carcass, carcass ether extract (CEE), carcass protein (CP), carcass moisture (CM), and carcass ash (CA) were correlated (P ≤ 0.01) with simple r values of 0.75, 0.31, 0.66, and 0.37, respectively. Equations to predict carcass fatness from rib dissection variables and ZH supplementation status were only able to account for 50 and 56%, of the variability of CF and CEE, respectively. Overall, the relationships quantified and equations developed in this investigation do not support use of 9/10/11 rib dissection for estimation of carcass composition of calf-fed Holstein steers.

Documentation of 50% water conservation in a single process at a beef abattoir.

Beef slaughter is water intensive due to stringent food safety requirements. We conducted a study at a commercial beef processor to demonstrate water conservation by modifying the mechanical head wash. We documented the initial nozzle configuration (112 nozzles), water pressure (275kPa), and flowrate (152L/head washed), then developed a 3-D CAD model to identify regions of water use redundancy. The mechanical head wash was modified by reducing nozzle count (72), decreasing pressure (138kPa) and flowrate (78.4L/head). To objectively document visual cleansing, heads were photographed at three locations post decapitation: 1) prior to manual wash, 2) prior to entering, and 3) upon exit of the mechanical head wash. Changes in red saturation between stations 1 and 3 provided an objective measure of relative cleanliness. Prior to altering operating parameters, the post-wash red saturation was 5%; after modification this increased slightly to 7.5%. Water use was reduced by 48.4% without altering head cleanliness acceptance.

Fabrication yields of serially harvested calf-fed Holstein steers fed zilpaterol hydrochloride.

Holstein steers ( = 110) were fed zilpaterol hydrochloride (ZH) for 0 or 20 d before slaughter during a 280-d serial harvest study. Cattle were harvested every 28 d beginning at 254 d on feed (DOF) and concluding at 534 DOF. After slaughter, carcasses were chilled for 48 h and then fabricated into boneless closely trimmed or denuded subprimals, lean trim, trimmable fat, and bone. Inclusion of ZH increased cold side weight (CSW) by 10.3 kg ( < 0.01; 212.7 vs. 202.4 kg [SEM 1.96]) and saleable yield by 10.4 kg ( < 0.01; 131.9 vs. 121.5 kg [SEM 1.16]) in calf-fed Holstein steer carcasses. Additionally, saleable yield as a percentage of CSW increased ( ≤ 0.01) by 2.19% (62.64 vs. 60.45% [SEM 0.22]) for cattle supplemented with ZH. Subprimal weights were heavier ( ≤ 0.05) from cattle that received ZH except for the bottom sirloin ball tip, back ribs, and outside skirt regardless of slaughter endpoint. Yield of top round, bottom round, and knuckle was increased ( ≤ 0.01) following ZH supplementation by 0.37, 0.24, and 0.18%, respectively. Yield of the top sirloin butt, strip loin, and tenderloin was increased ( ≤ 0.01) concurrent with ZH supplementation by 0.18, 0.11, and 0.09%, respectively. Regarding the rib primal, the rib eye roll tended ( = 0.08) to had increased yield (2.80 vs. 2.72% [SEM 0.03]) with ZH supplementation; both back ribs and blade meat exhibited increased ( ≤ 0.04) yields of 0.04%. Relative to the chuck primal, increased ( ≤ 0.03) yields of shoulder clod, pectoral meat, and mock tender were observed (0.13, 0.07, and 0.04%, respectively). Yield changes for subprimal brisket, plate, and flank were limited to increased ( < 0.01) proportion of flank steak and elephant ear (cutaneous trunci), 0.07 and 0.04%, respectively. Feeding duration notably altered ( ≤ 0.01) weights and percentages of all subprimals except the brisket. Saleable yield increased ( ≤ 0.01) by 0.192 kg/d with additional DOF. Moreover, trimmable fat and bone increased ( ≤ 0.01) by 0.146 and 0.050 kg/d, respectively. These data illustrate improved saleable meat yields for calf-fed Holstein steers supplemented with ZH and provide the beef industry knowledge of fabrication yield changes throughout a wide range of harvest endpoints.

Rapid Communication: Subclinical bovine respiratory disease - loci and pathogens associated with lung lesions in feedlot cattle.

Bovine respiratory disease (BRD) is an economically important disease of feedlot cattle that is caused by viral and bacterial pathogen members of the BRD complex. Many cases of subclinical BRD go untreated and are not detected until slaughter, when lung lesions are identified. The objectives of this study were to identify which BRD pathogens were associated with the presence of lung lesions at harvest and to identify genomic loci that were associated with susceptibility to lung lesions as defined by consolidation of the lung and/or the presence of fibrin tissue. Steers from a Colorado feedlot ( = 920) were tested for the presence of viral and bacterial pathogens using deep pharyngeal and mid-nasal swabs collected on entry into the study. Pathogen profiles were compared between cattle with or without lung consolidation (LC), fibrin tissue in the lung (FT), a combination of LC and FT in the same lung (lung lesions [LL]), and hyperinflated lungs (HIF) at harvest. Genotyping was conducted using the Illumina BovineHD BeadChip. Genomewide association analyses (GWAA) were conducted using EMMAX (efficient mixed-model association eXpedited), and pseudoheritabilities were estimated. The pathogen profile comparisons revealed that LC ( = 0.01, odds ratio [OR] = 3.37) and LL cattle ( = 0.04, OR = 4.58) were more likely to be infected with bovine herpes virus-1 and that HIF cattle were more likely to be infected with spp. ( = 0.04, OR = 4.33). Pseudoheritability estimates were 0.25 for LC, 0.00 for FT, 0.28 for LL, and 0.13 for HIF. Because pseudoheritability for FT was estimated to be 0, GWAA results for FT were not reported. There were 4 QTL that were moderately associated ( < 1 × 10) with only LC, 2 that were associated with only LL, and 1 that was associated with LC and LL. Loci associated with HIF included 12 that were moderately associated and 3 that were strongly associated (uncorrected P < 5 × 10-7). A 24-kb region surrounding significant lead SNP was investigated to identify positional candidate genes. Many positional candidate genes underlying or flanking the detected QTL have been associated with signal transduction, cell adhesion, or gap junctions, which have functional relevance to the maintenance of lung health. The identification of pathogens and QTL associated with the presence of lung abnormalities in cattle exhibiting subclinical BRD allows the identification of loci that may not be detected through manifestation of clinical disease alone.

Objective biometric measurements of calf-fed Holstein steers fed in confinement.

Understanding the maximum slaughter size for calf-fed Holstein steers based on hip-height has become a contemporary issue in the beef processing industry. Increased carcass size, in terms of both weight and length, has outpaced the ability of some abattoirs to handle the larger animals. Moreover, some abattoirs have begun rejecting animals that exceed 147.3 cm (58 inches) at the hip, creating a challenge for Holstein cattle feeders. The objective of this study was to quantify the skeletal growth rate of calf-fed Holstein steers fed in confinement. Hip-height of calf-fed Holstein steers ( ≤ 135) was measured every 28 d from 226 to 422 d on feed. Hip-height was a dependent variable modeled via linear regression procedures utilizing days of age and BW as independent variables. Additionally, logistic regression was used to estimate the probability of a steer exceeding a hip-height of 147.3 cm (58 inches) from independent variables of days of age and BW. The linear relationship of BW to hip-height had an adjusted value of 0.7112 (Hip-height, cm = [0.0593 × BW, kg] + 109.00) and on average the calf-fed Holstein steers grew 1.0 cm for each 16.9 kg of BW gain during the finishing phase. The 10%, 50%, and 90% probability of a steer exceeding 147.3 cm (58 inches) of hip-height was achieved at 563, 653, and 743 kg of BW, respectively. The linear relationship of days of age to hip-height had an adjusted value of 0.6687 (Hip-height, cm = [0.0937 × days of age] + 104.4) and the calf-fed Holstein steers grew 1.0 cm for each 10.7 d of age during the finishing phase. The 10%, 50%, and 90% probability of a steer exceeding 147.3 cm (58 inches) of hip-height was estimated to occur at 408, 459, and 510 d of age, respectively. Knowledge of Holstein steer growth rate in relation to BW and age may allow for more accurate sorting to prevent oversized cattle arriving at the abattoir and subsequent discounts or being rejected for slaughter.

National Beef Quality Audit-2016: Transportation, mobility, and harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and by-products.

The National Beef Quality Audit-2016 (NBQA-2016) was conducted to assess current transportation, mobility, and quality characteristics of U.S. fed steers and heifers. Data were collected at 17 beef processing facilities between March and November 2016. About 8,000 live cattle were evaluated for transportation and mobility, and about 25,000 carcasses were evaluated on the slaughter floor. Cattle were in transit to the slaughter facility for a mean duration of 2.7 h from a mean distance of 218.5 km using trailers with dimensions ranging from 17.84 m2 to 59.09 m2. Area allotted per animal averaged 1.13 m2 and ranged from 0.85 m2 to 2.28 m2. A total of 96.8% of cattle received a mobility score of 1 (walks easily, no apparent lameness). Identification types (35.1% had multiple) were lot visual tags (61.5%), individual tags (55.0%), electronic tags (16.9%), metal-clip tags (9.2%), bar-coded tags (0.05%), wattles (0.01%), and other (2.6%). Cattle were black-hided (57.8%), Holstein (20.4%), red-hided (10.5%), yellow-hided (4.8%), gray-hided (2.9%), brown-hided (1.3%), and white-hided (1.1%). Unbranded hides were observed on 74.3% of cattle; 18.6% had brands located on the butt, 6.3% on the side, and 1.3% on the shoulder (values exceed 100% due to multiple brands). For hide-on carcasses, 37.7% displayed no mud or manure; specific locations for mud or manure were legs (40.8%), belly (33.0%), tail region (15.5%), side (6.8%), and top-line (3.9%). Cattle without horns represented 83.3% of the sample, and cattle that did have horns measured: < 2.54 cm (5.5%), 2.54 to 12.7 cm (8.3%), and > 12.7 cm (2.9%). Carcasses without bruises represented 61.1% of those sampled, whereas 28.2% had 1, 8.2% had 2, 2.1% had 3, and 0.3% had 4 bruises. Of those carcasses with a bruise, the bruise was located on the loin (29.7%), round (27.8%), chuck (16.4%), rib (14.4%), and brisket/plate/flank (11.6%). Frequencies of offal condemnations were livers (30.8%), lungs (18.2%), viscera (16.3%), hearts (11.1%), heads (2.7%), and tongues (2.0%). Compared to NBQA-2011, fewer cattle were identified for traceability, fewer were black-hided, a greater number were Holstein cattle, more with no brand and no horns, fewer without bruises, more liver, lung, and viscera condemnations, and fewer heads and tongues were condemned. The NBQA remains an influential survey for the U.S. beef industry to provide benchmarks and strategic plans for continued improvement of beef quality and consistency.

National Beef Quality Audit-2016: Transportation, mobility, live cattle, and carcass assessments of targeted producer-related characteristics that affect value of market cows and bulls, their carcasses, and associated by-products.

The National Beef Quality Audit-2016 marks the fourth iteration in a series assessing the quality of live beef and dairy cows and bulls and their carcass counterparts. The objective was to determine the incidence of producer-related defects, and report cattle and carcass traits associated with producer management. Conducted from March through December of 2016, trailers (n = 154), live animals (n = 5,470), hide-on carcasses (n = 5,278), and hide-off hot carcasses (n = 5,510) were surveyed in 18 commercial packing facilities throughout the United States. Cattle were allowed 2.3 m2 of trailer space on average during transit indicating some haulers are adhering to industry handling guidelines for trailer space requirements. Of the mixed gender loads arriving at processing facilities, cows and bulls were not segregated on 64.4% of the trailers surveyed. When assessed for mobility, the greatest majority of cattle surveyed were sound. Since the inception of the quality audit series, beef cows have shown substantial improvements in muscle. Today over 90.0% of dairy cows are too light muscled. The mean body condition score for beef animals was 4.7 and for dairy cows and bulls was 2.6 and 3.3, respectively. Dairy cattle were lighter muscled, yet fatter than the dairy cattle surveyed in 2007. Of cattle surveyed, most did not have horns, nor any visible live animal defects. Unbranded hides were observed on 77.3% of cattle. Carcass bruising was seen on 64.1% of cow carcasses and 42.9% of bull carcasses. However, over half of all bruises were identified to only be minor in severity. Nearly all cattle (98.4%) were free of visible injection-site lesions. Current results suggest improvements have been made in cattle and meat quality in the cow and bull sector. Furthermore, the results provide guidance for continued educational and research efforts for improving market cow and bull beef quality.

National Beef Quality Audit - 2016: Survey of carcass characteristics through instrument grading assessments.

The instrument grading assessment portion of the National Beef Quality Audit (NBQA) - 2016 allows the unique opportunity to evaluate beef carcass traits over the course of a year. One week of instrument grading data was collected each month from 5 beef processing corporations encompassing 18 facilities from January 2016 through December 2016 ( = 4,544,635 carcasses). Mean USDA yield grade (YG) was 3.1 with 1.37 cm fat thickness (FT), 88.9 cm LM area, 393.6 kg HCW, and 2.1% KPH. Frequency distribution of USDA YG was 9.5% YG 1, 34.6% YG 2, 38.8% YG 3, 14.6% YG 4, and 2.5% YG 5. Increases in HCW and FT since the NBQA-2011 were major contributors to differences in mean YG and the (numerically) increased frequency of YG 3, 4, and 5 carcasses found in the current audit. Mean marbling score was Small, and the distribution of USDA quality grades was 4.2% Prime, 71.4% Choice, 21.7% Select, and 2.7% other. Frequency of carcasses grading Prime on Monday (6.43%) was numerically higher than the average frequency of carcasses grading Prime overall (4.2%). Monthly HCW means were 397.6 kg in January, 397.2 kg in February, 396.5 kg in March, 389.3 kg in April, 384.8 kg in May, 385.0 kg in June, 386.1 kg in July, 394.1 kg in August, 399.1 kg in September, 403.9 kg in October, 406.5 kg in November, and 401.9 kg in December. Monthly mean marbling scores were Small in January, Small in February, Small in March, Small in April, Small in May, Small in June, Small in July, Small in August, Small in September, Small in October, Small in November, and Small in December. Both mean HCW and mean marbling score declined in the months of May and June. The month with the greatest numerical frequency of dark cutters was October (0.74%). Comparison of overall data from in-plant carcass and instrument grading assessments revealed close alignment of information, especially for YG (3.1 for in-plant assessment versus 3.1 for instrument grading) and marbling (Small for in-plant assessment versus Small for instrument grading). These findings allow the beef industry access to the greatest volume of beef value-determining characteristics for the U.S. fed steer and heifer population than ever reported, resulting in potentially more precise targeting of future quality and consistency efforts.

National Beef Quality Audit-2016: In-plant survey of carcass characteristics related to quality, quantity, and value of fed steers and heifers.

The National Beef Quality Audit (NBQA)-2016 used in-plant cooler assessments to benchmark the current status of the fed steer and heifer beef industry in the United States. In-plant cooler assessments ( = 9,106 carcasses) were conducted at 30 facilities, where approximately 10% of a single day's production were evaluated for USDA quality grade (QG) and yield grade (YG) factors. Frequencies of evaluated traits were 66.5% steer and 33.4% heifer sex classes and 82.9% native, 15.9% dairy-type, and 1.2% estimated breed types. Mean USDA YG factors were 1.42 cm for adjusted fat thickness, 89.5 cm for LM area, 390.3 kg for HCW, and 1.9% for KPH. Mean USDA YG was 3.1, with a frequency distribution of 9.6% YG 1, 36.7% YG 2, 39.2% YG 3, 12.0% YG 4, and 2.5% YG 5. Mean USDA QG traits were Small for marbling score, A for overall maturity, A55 for lean maturity, and A for skeletal maturity. Mean USDA QG was Select with a frequency distribution of QG of 3.8% Prime, 67.3% Choice, 23.2% Select, and 5.6% lower score. Lower score included dark cutter (1.9%), blood splash (0.1%), and hard bone, which are USDA overall maturity scores of C or older (1.8%). Marbling score distributions were 0.85% Slightly Abundant or greater, 7.63% Moderate, 23.54% Modest, 39.63% Small, 23.62% Slight, and 0.83% Traces or less. Carcasses that were Choice or Select and USDA YG 2 or 3 accounted for 70.7% of the carcasses evaluated. Compared with the previous NBQA, we found a numerical increase in mean USDA YG, USDA QG, adjusted fat thickness, HCW, LM area, and marbling score with an increase in dairy-type carcasses and percentage of carcasses grading USDA Prime and Choice as well as frequency of USDA YG 4 and 5. The findings from this study will be used by all segments of the industry to understand and improve the quality of fed steer and heifer beef that is being produced.

The effect of days on feed and zilpaterol hydrochloride supplementation on feeding behavior and live growth performance of Holstein steers.

This experiment was designed to study the effect of days on feed (d 225-533) and zilpaterol hydrochloride (ZH) supplementation on Holstein steer ( = 110) performance and feeding behavior as part of a serial slaughter trial. Steers were randomly assigned to 1 of 11 harvest groups with 10 steers ( = 5 control and = 5 ZH; ZH at 8.33 mg/kg diet) harvested each 28 d. Steers were weighed every 28 d (d 225, 253, 281, 309, 337, 365, 393, 421, 449, 477, 505, and 533); individual daily meal consumption data for each steer were recorded using GrowSafe technology. In the pretreatment period, dry matter intake expressed a negative quadratic relationship with days on feed (DOF) {DMI = -5.7120 + (0.08370 x DOF)- (0.00011 x DOF); Adj. = 0.2574; RMSE = 0.25 75; 0.01}. A linear increase in BW ( < 0.01) occurred during the pretreatment 308 d period from 466 to 844 kg, {BWend = 137.61 + (1.4740 x DOF); Adj. = 0.8819; RMSE = 37.06; < 0.01}, whereas ADG and G:F decreased linearly. Dry matter intake per meal exhibited a quadratic relationship over days on feed and peaked ( < 0.01) during d 365 to 392 at 1.065 kg coinciding with the highest numerical daily DMI (11.19 kg). Daily consumption visit duration differed ( < 0.01) during the 308 d period, with a low of 52.29 min (d 337-364) and a high of 55.59 min (d 365-392). Consumption rate peaked at 714 g/min (d 337-364) and exhibited a quadratic relationship to DOF. The difference ( < 0.04) in DMI between control and ZH treated cattle across all 11 harvest groups averaged 0.575 kg. Moreover, ZH treatment resulted in decreased ( 0.01) DMI per meal event of 0.093 kg. Gain to feed tended to improve ( = 0.06) with ZH treatment by 0.017 kg gain per kg feed relative to the control cattle. Daily bunk, consumption, and meal visit durations were influenced by ZH during the 20 d treatment period ( = 0.01); the average difference between control and ZH supplemented cattle over the 308 d trial was 9.09, 8.71, and 11.39 min per d, respectively. The data collected in this trial indicate live growth performance and feeding behavior were impacted by both DOF and ZH supplementation.

Carcass grading characteristics of serially harvested calf-fed Holstein steers fed zilpaterol hydrochloride.

Serial harvests were conducted using Holstein steers ( = 110) fed zilpaterol hydrochloride (ZH) for 0 or 20 d prior to harvest. Steers were harvested in 28-d increments beginning at 254 d on feed (DOF) and ending at 534 DOF. After harvest and a 36-h chill period, carcasses were evaluated using grading methods standard for the United States (USDA), Canada (Canadian Beef Grading Association [CBGA]), and Japan (Japanese Meat Grading Agency [JMGA]). No ZH treatment differences ( = 0.81) were detected for 12th-rib fat thickness; however, additional DOF resulted in a daily linear increase ( < 0.01) of 12th-rib fat thickness by 0.004 cm/d. Longissimus muscle area was increased ( < 0.01) by 8.7 cm with ZH supplementation and linearly increased ( < 0.01) 0.08 cm2/d with additional DOF. Calculated USDA yield grade (YG) decreased ( < 0.01) 0.33 units due to ZH treatment and linearly increased ( < 0.01) 0.009 units/d. Steers supplemented with ZH exhibited increased ( < 0.01) CGBA LM width; however, no difference ( = 0.37) was detected in CGBA LM length. No ZH treatment differences ( = 0.64) were observed for CBGA fat class; however, CGBA fat class linearly increased ( < 0.01) by 0.01 units/d. No ZH differences ( ≥ 0.17) were detected for the CBGA estimated lean percentage or YG equations. Evaluation for JMGA occurs at the sixth and seventh rib interface; LM area was 4.6 cm2 greater ( = 0.02) for cattle supplemented with ZH and linearly increased ( < 0.01) by 0.07 cm2/d with additional DOF. Subcutaneous fat thickness was not different among ZH treatments ( = 0.10) but linearly ( < 0.04) increased ( < 0.01) by 0.005 cm/d with additional DOF using the JMGA grading method. No difference ( ≥ 0.21) was calculated between ZH treatments or DOF for JMGA estimated yield. No ZH treatment differences ( = 0.85) were detected in USDA marbling score; however, marbling linearly increased ( < 0.01) 0.07 units/d. These data illustrate the impact of ZH and increasing DOF on economically important carcass grading outcomes used in the USDA, CBGA, and JMGA grading programs.

The effect of zilpaterol hydrochloride supplementation on energy metabolism and nitrogen and carbon retention of steers fed at maintenance and fasting intake levels.

An indirect calorimetry trial examined energy metabolism, apparent nutrient digestibility, C retention (CR), and N retention (NR) of cattle supplemented with zilpaterol hydrochloride (ZH). Beef steers ( = 20; 463 ± 14 kg) blocked ( = 5) by weight and source were individually fed and adapted to maintenance energy intake for 21 d before allotment to ZH (90 mg/steer∙d) or no ß-adrenergic agonist treatment (control [CONT]) for 20 d (455 ± 14 kg at the start of treatment). Respiration chambers = 4 were used to quantify heat production (HP) during maintenance (d 12 to 16 of the ZH period) and fasting heat production (FHP; d 19 to 20 of ZH period; total 4 d of fast). Steers were harvested after a 6-d ZH withdrawal and carcasses were graded 24 h after harvest. Control cattle lost more BW ( < 0.01; 9 kg for CONT and 2 kg for ZH-treated) during maintenance whereas the BW loss of ZH-treated steers was greater ( < 0.01; 9 kg for ZH-treated and vs. 4 kg, for CONT) during FHP; no differences ( ≥ 0.76) were detected for G:F, ADG, and end BW. No differences in DMI, apparent nutrient digestibility, O consumption, or CH production ( ≥ 0.12) were detected; however, ZH-treated cattle had greater CO production during maintenance ( = 0.04; 23.6 L/kgBW for ZH-treated and 22.4 L/kg BW for CONT). Digestible energy and ME did not differ ( ≥ 0.19); however, urinary energy was greater ( = 0.05; 0.091 Mcal for CONT and 0.074 Mcal for ZH-treated) in CONT cattle. Steers treated with ZH tended to have greater HP ( = 0.09; 12.44 Mcal for ZH-treated and 11.69 Mcal for CONT), but the effect was reduced on a BW basis ( = 0.12; 0.126 Mcal/kg BW0.75 for ZH-treated and 0.120 Mcal/kg BW0.75 for CONT vs. 0.120 Mcal/kg BW). No treatment difference in FHP was observed ( ≥ 0.32) although CO production (L/steer) increased with ZH treatment ( = 0.04; 1,423 L/steer for ZH-treated and 1,338 L/steer for CONT). Control cattle excreted more ( = 0.05) N in urine (39.8 g/d for CONT and 32.4 g/d for ZH-treated); therefore, NR ( = 0.07; 22.14 g/d for ZH-treated and 14.12 g/d for CONT steers) tended to be greater for ZH-fed steers. Steers treated with ZH lost more C via CO ( = 0.04; 1,036.9 g/d for ZH-treated and 974.3 g/d for CONT) although total CR did not differ ( ≥ 0.23). Empty BW, HCW, and harvest yields (g/kg empty BW) were not different ( ≥ 0.13), whereas ZH increased dressed yield ( = 0.02; 62.12 % for ZH-treated and 60.65% for CONT) and LM area ( = 0.02; 77.81 cm for ZH-treated and vs. 70.90 cm for CONT). Separable carcass lean and actual skeletal muscle protein (SMP) were increased with ZH ( ≤ 0.04; 201.6 and 41.2 kg, respectively for ZH-treated and 196.0 and 38.4 kg, respectively for CONT). Results from this trial indicate that ZH treatment increased ( = 0.03) SMP and tended ( ≥ 0.07) to increase NR and modify HP during maintenance by increasing CO production.

Byproduct yields of serially harvested calf-fed Holstein steers fed zilpaterol hydrochloride.

A 2 × 11 factorial treatment structure was applied in a completely randomized experimental design to investigate differences in noncarcass tissue among serially harvested Holstein steers. Steers ( = 110) were randomly assigned to 1 of 2 dietary treatments: a ration supplemented with zilpaterol hydrochloride (ZH) fed at a rate of 8.3 mg/kg DM for 20 d followed by a 3-d withdrawal or a control ration with no ZH included in the diet. Within treatment, steers were assigned to harvest groups of 254, 282, 310, 338, 366, 394, 422, 450, 478, 506, or 534 d on feed (DOF) prior to initiation of the trial. Cattle fed ZH realized an empty BW (EBW) increase ( ≤ 0.03) of 2.8% (644.2 vs. 626.4 kg [SEM 5.4]) and a HCW increase of 5.0% (429.1 vs. 408.4 kg [SEM 4.0]) with a concomitant 12% reduction (45.1 vs. 51.2 kg [SEM 3.1]) in gastrointestinal contents and 2.1 percentage unit increase in dressed carcass yield (62.1 vs. 60.0% [SEM 0.01]). Additionally, ZH supplementation decreased (P ≤ 0.03) the absolute weight of the liver and kidneys by 0.3 and 0.1 kg, respectively. When noncarcass components were expressed on an empty body basis (g/kg EBW), reductions ( ≤ 0.01) in the limbs (18.8 vs. 19.5 g/kg EBW [SEM 0.1]), hide (81.1 vs. 78.1 g/kg EBW [SEM 0.7]), liver (14.2 vs. 13.2 g/kg EBW [SEM 0.2]), kidneys (2.6 vs. 2.3 g/kg EBW [SEM 0.04]), small and large intestines (74.9 vs. 69.6 g/kg EBW [SEM 1.2]), and gastrointestinal tract (119.8 vs. 113.4 g/kg EBW [SEM 1.3]) were observed with ZH supplementation. Additionally, there was a tendency ( = 0.07) for the proportion of total offal to be reduced (253.2 vs. 247.4 g/kg EBW [SEM 2.5]) with ZH supplementation. Empty BW and HCW linearly increased ( < 0.01) by 1.16 and 0.758 kg/d ( < 0.01), respectively, with additional DOF. The weight of the liver and intestines linearly increased ( < 0.01) by 0.007 and 0.133 kg/d ( < 0.01), respectively, with additional DOF. These data indicate the magnitude of change in noncarcass tissues that can be expected when calf-fed Holstein steers are supplemented with ZH.

Influence of dental carcass maturity classification on carcass traits and tenderness of longissimus steaks from commercially fed cattle.

Two hundred beef carcasses were randomly selected by dental classification (zero, two, four, six, or eight permanent incisors) from a population of 11,136 carcasses harvested by a large commercial beef processor. Warner-Bratzler shear force and trained sensory panel evaluations of longissimus thoracis steaks as well as cooking and carcass traits were evaluated for differences among dental classes. No differences in Warner-Bratzler shear force (P = 0.60), sensory panel evaluations (P = 0.64) for tenderness, or percentage of total cooking loss (P = 0.73) were found among the five dental classes. Longissimus muscle color, USDA marbling score, hot carcass weight, adjusted fat thickness, longissimus muscle area, and USDA yield grade did not differ among the five dental classes. A significant dental classification x sex interaction indicated that heifers advanced in skeletal and overall maturity at a much faster rate than steers. An increase of intramuscular fat was associated (P < 0.05) with decreased shear force (r = -0.31), whereas darkening of the lean (r = 0.16), advancing lean maturity (r = 0.21), and increased evaporative cooking loss (r = 0.39) were associated (P < 0.05) with increased shear force values. Warner-Bratzler shear force measurements were not related to sensory panel overall tenderness scores. Carcass traits accounted for a relatively small proportion of the variation in tenderness of longissimus steaks, and dental classification was not related to tenderness.

A comparison of the USDA ossification-based maturity system to a system based on dentition.

Two studies using commercially fed cattle were conducted to determine the relationship of the USDA bone ossification-based maturity system to one based on the number of permanent incisors present at slaughter. These studies showed that 91.5 to 100% of cattle with zero permanent incisors (< 23.8 mo of age), 89.1 to 97.5% of cattle with two permanent incisors (23.8 to 30.4 mo of age), 75 to 82.2% of cattle with four permanent incisors (30.4 to 38.0 mo of age), 64 to 72.5% of cattle with six permanent incisors (38.0 to 45.3 mo of age), and 40% of cattle with eight permanent incisors (> 45.3 mo of age) were graded as A maturity by the USDA maturity classification system. Kappa tests revealed no statistical relationship between the dentition- and skeletal ossification-based maturity systems. Dentition-based maturity agreed with ossification/lean maturity for only 162 of 1,264 carcasses in Exp. 1 and only 54 of 200 carcasses in Exp. 2. Cattle with two, four, six, or eight permanent incisors were classified in more youthful categories of USDA bone ossification/lean maturity than they should have been. Male cattle were more likely to be misclassified into a younger age category by the USDA system than were female cattle. It seems that determining physiological maturity by number of permanent incisors rather than by the current USDA method of subjectively evaluating skeletal and lean maturity may prove to be a more accurate technique of sorting beef carcasses into less-variable age groups.

Mechanical probes can predict tenderness of cooked beef longissimus using uncooked measurements.

Two experiments were conducted to determine the effectiveness of using mechanical probes and objective color measurement on beef LM to predict cooked tenderness. In Exp. 1, sharp needle (SN), sharp blade (SB), blunt needle (BN), blunt blade (BB), and plumb bob (PB) probes were used to measure uncooked LM (n = 29) at 2 d postmortem in both a perpendicular and parallel orientation to the long axis of the strip loin. Additionally, instrumental color measurements were measured on uncooked muscle at 2 d postmortem. Steaks for trained sensory panel (TSP) and Warner-Bratzler shear force (WBSF) measurements were aged 14 d postmortem before cooking. Probe measurements taken perpendicular to the long axis of the LM were not correlated (P = 0.22 to 0.82) to TSP tenderness. Probe measurements (BB, BN, SN, SB, and PB) taken parallel to the long axis were correlated to TSP tenderness (r = -0.57, -0.40, -0.77, -0.52, and -0.53, respectively). A regression equation using the SN probe to predict TSP tenderness had a R2 value of 0.74. The SB probe combined with L* accounted for 45% of the variation in TSP tenderness, whereas the PB probe combined with L* accounted for 56% of the variation in TSP tenderness. A second experiment (n = 24) was conducted using the SN, SB, and PB probes on uncooked sections at 2 d and on cooked steaks at 14 d postmortem. Probe measurements on cooked steaks were not correlated to TSP tenderness. New regression equations were calculated using the probe measurements on uncooked steaks from both experiments. Prediction equations formulated with L* values and either SN, SB, or PB probes accounted for 49, 50, and 47% of the variability in TSP tenderness scores, respectively. An equation using WBSF of cooked steaks to predict TSP tenderness had an R2 of 0.58. Of the steaks predicted to be tender (predicted tenderness > 5.0) by the equations using the SN, SB, and PB probes on uncooked steaks and WBSF on cooked steaks, 85, 88, 80, and 84%, respectively, were actually tender (TSP tenderness > 5.0). Mechanical probe measurements of uncooked steaks at 2 d postmortem can potentially classify strip loins into groups based on tenderness, as well as WBSF measurements, which are more costly and time consuming.

Mechanical measures of uncooked beef longissimus muscle can predict sensory panel tenderness and Warner-Bratzler shear force of cooked steaks.

Two experiments were conducted to investigate mechanical measures of tenderness on uncooked USDA Select longissimus muscle as a means to predict Warner-Bratzler shear force (WBSF) and trained sensory panel tenderness (SPT) of cooked steaks. In Exp. 1, strip loins (n = 24) were aged 14 d postmortem and fabricated into steaks (2.54 cm). Medial, center, and lateral locations within uncooked steaks were evaluated by a plumb bob device and correlated with WBSF and SPT of cooked steaks. In Exp. 2, 24 strip loins were used to evaluate how well plumb bob and needle probe devices used on uncooked steaks predicted WBSF and SPT of cooked steaks. At 2 d postmortem, two steaks were fabricated from the anterior end. One uncooked steak (2.54 cm) was assigned to the plumb bob treatment and the other uncooked steak (5.08 cm) was assigned to needle probe treatment. At 14 d postmortem, one uncooked steak (5.08 cm) was assigned to needle probe treatment, a second uncooked steak (2.54 cm) was assigned to plumb bob treatment, whereas the remaining steaks (2.54 cm) were cooked and evaluated by a trained sensory panel and WBSF device. In Exp. 1, average plumb bob values were negatively correlated (P < 0.05) to average SPT scores (r = -0.48). However, correlations between WBSF and plumb bob values for medial, lateral, and average of all sections were not significant (P > 0.05). In Exp. 2, regression models to predict SPT from needle probe and plumb bob measurements individually taken at 2 d postmortem had R2 of 0.54 and 0.51, respectively. Combining needle probe and plumb bob measurements resulted in an R2 of 0.76; when quadratic terms for both variables were in the model, the R2 was 0.80. Regressing needle probe and plumb bob measurements at 2 d postmortem with WBSF produced R2 values of 0.51 and 0.45, respectively. If linear terms of both probes were combined to predict WBSF, the R2 increased to 0.77. An equation to predict WBSF, including both the linear and quadratic terms of needle probe and plumb bob measurements, resulted in an R2 of 0.84. Using plumb bob and needle probe devices on uncooked longissimus muscle at 2 d postmortem can predict cooked WBSF and SPT of USDA Select Grade steaks at 14 d postmortem.

Effects of calcium salts on beef longissimus quality.

The objective of this research was to evaluate the effects of injection marination with calcium salts on beef longissimus quality traits. Strip loins were injected (11% by weight) with distilled water or a 0.1, 0.2, or 0.3 M solution of calcium ascorbate, calcium chloride, or calcium lactate. Non-injected loins served as controls. Visual and instrumental color evaluations indicated that calcium ascorbate accelerated myoglobin oxidation, and increasing molar concentration of any calcium salt caused faster (P<0.05) discoloration. Aerobic microbial plate counts were lower (P<0.05) for treatments containing calcium lactate than those with calcium chloride or calcium ascorbate. Calcium ascorbate inhibited lipid oxidation whereas calcium lactate and calcium chloride appeared to be pro-oxidants of lipid oxidation. No differences for Warner-Bratzler shear force or sensory panel tenderness were found among the calcium salts; however, 0.3 M treatments had lower shear values and were judged more tender than 0.1 M treatments. Calcium ascorbate and calcium chloride treatments resulted in less (P<0.05) beef flavor and more (P<0.05) off-flavors than calcium lactate treatments. In addition, 0.1 M treatments had higher (P<0.05) beef flavor scores while 0.3 M treatments had higher (P<0.05) off-flavor scores. Considering the effects on color life, microbial inhibition, shear force, and sensory traits, we recommend injecting beef longissimus with a 0.1 M solution of calcium lactate to enhance both uncooked and cooked quality.