Slaughter End Points Research Articles

Carcass Yield and Subprimal Cutout Value of Beef, High- and Low-Yielding Beef × Dairy, and Dairy Steers

This study compared carcass yield and cutout value of conventional beef and dairy cattle to high-yielding (HY) and low-yielding (LY) crossbred beef × dairy cattle and identified the contribution of carcass regions to carcass yield andcutout value among beef × dairy crossbreds. Carcasses of conventional beef, beef × dairy crossbred, and dairy cattle were selected according to industry-average slaughter endpoints for their cattle type. Carcasses were fabricated at a commercial processing facility, and weights of carcass components were obtained. Post hoc subsampling was used to segregate HY and LY beef × dairy crossbreds based on subprimal yield. Multiple linear regression was used to assess carcass yield and sub-primal cutout value between the 4 cattle types (n=21 to 26 per cattle type). Beef cattle and HY crossbreds produced 1.59 to 3.04 percentage units greater (P<0.05) subprimal yield than LY crossbreds and dairy cattle. Dairy cattle produced at least 1.16 percentage units more (P<0.05) bone than any other cattle type. Subprimal to bone was not different (P>0.05) between HY crossbreds and beef cattle, and subprimal to fat was lesser (P<0.05) in HY crossbreds than beef cattle. Subprimal cutout value was more than 5 US dollars (USD)/45.4 kg different (P<0.05) between cattle types, which were ranked HY crossbreds > beef cattle > LY crossbreds > dairy cattle. In beef × dairy cattle, subprimal to bone in the round contributed most greatly to an increase (P=0.02), by 3.79 USD/45.4 kg, in subprimal cutout value. Together, these results suggested carcass value of beef × dairy cattle may be maximized when cattle are harvested at a lesser overall fatness than conventional beef cattle and when considerable muscling, especially in the round, is achieved.

Impact of planning horizon length on traits in an economic breeding goal and ranking of selection candidates in beef cattle

Abstract In beef production herds, unique situations such as breeding system, economic parameters, and current phenotypic performance can affect the emphasis of traits in the breeding goal and consequently the weighting of traits within a selection index. An often overlooked component of breeding goals is the planning horizon, or the time span to consider the economic impact of a selection decision, that varies between enterprises. A platform for constructing economic selection indexes (iGENDEC) was used to determine the impact of planning horizon length, breeding system, and sale endpoint on the relative emphasis of traits in the breeding goal and the re-ranking of selection candidates. As part of this investigation, the adjustment of phenotypic means for hot carcass weight and planning horizons were used to determine the impact of the relative emphasis on hot carcass weight as its mean approached a predetermined discount threshold. General-purpose indexes were created for animals sold at weaning and slaughter for three breeding systems with six different planning horizons (2, 5, 10, 20, 30, and 50 yr). As planning horizon increased, the relative emphasis on weaning weight or hot carcass weight, which affected revenue, decreased while the relative emphasis on stayability and mature weight increased. As the phenotypic mean for hot carcass weight approached and surpassed a predetermined discount threshold, the relative emphasis decreased before increasing again, once the mean weight surpassed the threshold. Rank correlations between indexes with different sale endpoints was 0.71 ± 0.1. Within a slaughter endpoint, re-ranking occurred between short and long planning horizons (r = 0.78 ± 0.09) while that of a weaning endpoint was less substantial (r = 0.85 ± 0.10). Jacard index scores between indexes with different planning horizons ranged from 39.7% to 87.9% and from 47.9% to 78.7% for weaning and carcass endpoints, respectively, for the top 5% of selection candidates. These results illustrate that the determination of a planning horizon can impact the rank of selection candidates and increases in net profit.

Performance, Intake, Feed Efficiency, and Carcass Characteristics of Young Nellore Heifers under Different Days on Feed in the Feedlot.

Two studies evaluated the productive characteristics of young Nellore heifers receiving different days on feed (DOF) to determine the biological slaughter endpoint. In Experiment 1 (Exp. 1), fifty-one Nellore heifers [324 ± 19.3 kg of body weight (BW); 16 ± 1 months] were split into three DOF lengths (45, 75, or 105 days), while in Experiment 2 (Exp. 2), thirty-six Nellore heifers (362 ± 25.5 kg of BW; 18 ± 1 months of age) were split into three DOF lengths (45, 90, or 135 days). In both studies, all animals were distributed in complete randomized blocks according to initial BW and stratified via carcass ultrasound. The diet was supplied ad libitum, allowing 3% of refusals. The point at which the animals achieved 25% of ether extract of shrunk body weight (EESBW) was defined as the biological endpoint. Thus, relationships were made between some characteristics obtained in both studies. Positive linear relationships were found between backfat thickness (BFT) vs. EESBW (p < 0.001, r = 0.84) and BFT vs. body weight (p < 0.001, r = 0.77). Our results suggest that the biological slaughter endpoint for young Nellore heifers is 6.97 mm of backfat thickness or 402 kg shrunk body weight, corresponding to around 75 DOF.

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.

Evaluation of terminal sire breeds for hair sheep production systems: Feedlot environment

Improving carcass merit while maintaining parasite resistance in Katahdin crossbred lambs has potential to improve profitability for U.S. sheep producers. To assess crossbred lamb parasite resistance, carcass merit and gain, purebred Katahdin ewes from the Southwest Virginia Agricultural Research and Extension Center (Glade Spring, VA) were mated to Katahdin (KT), Suffolk (SU) or Texel (TX) rams for three years. Lambs were born and raised in Virginia. Two weeks post-weaning, lambs were transported to the West Virginia University Animal Science Farm (Morgantown, WV). Lambs were dewormed and transitioned to a complete pellet (16% CP) and fed ad lib for the duration of the study. After transition, all lambs were infected with 10,000 Haemonchus contortus L3 larvae (HcL3) in suspension given orally. Weights, blood and fecal samples were collected weekly. After a 5 week primary infection, all lambs were treated with levamisole (8 mg/kg) and rested for 2–3 weeks, after which, lambs were challenge infected with 10,000 HcL3 and sampled weekly until slaughter endpoint in Years 1&2. Ultrasonic determination of REA and fat depth occurred 1 week prior to slaughter in Years 1&2. In Year 3 carcass evaluation did not occur and ultrasonic measurements were taken at termination of the trial. In Years 1&2, 5 lambs from each sire group (n = 15) were randomly selected for carcass analysis at the Virginia Tech Meats Laboratory. No significant sire effect differences were observed in FEC during primary infections across all 3 years. Fecal egg count of KT lambs peaked at week 6 during challenge infection but reduced FEC rapidly one week later. SU-sired lambs grew faster to a larger body weight than TX sired lambs (55.72 kg vs. 49.51 kg; 0.37 kg/d vs. 0.32 kg/d, P < 0.0001), with KT progeny having the least amount of weight gain (44.8 kg; 0.30 kg/d). Analysis of REA using ultrasound and live carcass measurements exhibited no difference between SU- (16.92 cm2) or TX-sired lambs (17.10 cm2) but both breeds were significantly higher than Katahdin lambs (13.67 cm2;P < 0.01). Leg score favored SU- (11.8) and TX-sired (12.0) lambs compared to KT-sired lambs (10.7;P < 0.01). Feed efficiency measured in RFI showed no significant difference between KT-, SU- or TX sired lambs (−0.08, 0.04, −0.04 kg/d respectively; P = 0.65). Taken together these data demonstrate that carcass merit of TX-sired lambs is equivalent to SU-sired lambs supporting the option of using an alternative terminal sire on Katahdin ewes without detrimental loss of parasite resistance in crossbred progeny.

Performance, carcass and meat traits of beef steers finished on small-grain winter annuals in winter or on alfalfa pasture in summer

Performance and carcass traits of beef steers finished on small-grain winter annual pastures (SGWA) or alfalfa were compared. Treatments consisted of pure stands of cereal rye, triticale, wheat or alfalfa (Rye, Trit, Wht, and Alf, respectively). The 3 SGWA species were grazed during winter and early spring. Alfalfa was grazed during spring and summer. Three pasture replicates were assigned to each treatment with 10 animals each. A minimum of 7-mm subcutaneous rib fat thickness (determined by ultrasound) was defined as slaughter endpoint. After a 98-d finishing period all animals from Rye, Trit and Wht reached the target, and were ready for harvest. Alfalfa animals were slaughtered after 120 days. After slaughter, carcasses were individually graded and weighed to determine hot carcass weight (HCW) and hot carcass yield (HCY) was calculated. Seventy-two h post-slaughter, a section of steaks including the longissimus thoracis muscle (LT) was removed from the left side of each carcass for analysis including rib fat thickness (RFT), LT area (LTA), Warner-Bratzler-shear force (WBsf), drip-loss, cooking loss, instrumental color, muscle pH, sensory analysis, intramuscular fat content and lipid profile. Proximate composition, and lipid profiles of pastures offered were also determined. Alf animals had lower (P < 0.01) ADG than SGWA animals. Alfalfa animals took 22 days longer to reach the slaughter point. However, no pasture effects were detected (P ≥ 0.14) for HCY, LTA, RFT, WBsf, pH, muscle a* and b*, and subcutaneous fat L*, a* and b* color parameters. Muscle L* was greater (P < 0.05) and drip and cooking loss were lower (P ≤ 0.05) for Alf. Sensory panel scored Alf beef of greater (P < 0.01) juiciness, tenderness and beef-flavor. Rye beef was attributed highest off-flavor score. Alfalfa and Wht beef showed similar (P = 0.40) FA content, higher (P ≤ 0.02) than Rye and Trit beef. Rye beef had the lowest (P ≤ 0.02) FA content. Within the FA fraction, Alf had lower (P ≤ 0.02) proportion of SFA, greater t-MUFA content, greater (P ≤ 0.01) total n-3 concentration and the lowest n-6/n-3 ratio (P ≤ 0.01). Alfalfa beef resulted in greater (P ≤ 0.01) total CLA concentration. Although lipid profiles of forages related to observations in lipid profiles of beef, differences in drip and cooking loss and sensory attributes of beef that favored of alfalfa finishing were not explained in animal performance and fatness.

Perception of consultants, feedlot owners, and packers regarding the optimal economic slaughter endpoint in feedlots: a national survey in Brazil (Part I)

Little information exists regarding the optimal economic slaughter endpoint (OSE) for feedlot-finished cattle in Brazil. This study investigated the perceptions of Brazilian feeders regarding the optimal time for slaughter. A total of 52 interviews were conducted involving nutritionist-consultants (n = 23), feedlot owners (n = 21), and packer-owned feedlots (n = 8). The results showed that 65% of the interviewees used weight and fat cover, both estimated visually, to determine the moment for slaughter. Identifying the ideal time for slaughter was considered a challenge for respondents, and 85% of them recognized that their current slaughter endpoint identification method needed improvements. Regarding decision support systems, 58% of respondents reported they would purchase a computer program to help identify OSE, and 73% would be interested in incorporating a prototype of such a system into their feedlots. Carcass dressing (38%) and price (25%) were the main factors driving the feeder’s choice of meatpacker, followed by carcass premiums (10%). Meat quality was found to be an irrelevant criterion for Brazilian meatpackers in awarding both premiums (5%) and deductions (3%). Slaughter endpoint is determined subjectively by the Brazilian feeders, based on a visual evaluation of both weight and fatness.

The Effects of Sire Line, Slaughter Weight, and Gender on Pork Quality and Yield Characteristics

ObjectivesPork continues to be a significant source of highly valued animal protein for the growing global population. Due primarily to the push for lean yield in the US swine industry, there is a demand from consumers for higher quality pork, while producers continue to desire improved yields. The purpose of this study is to determine the effects of gender and slaughter endpoint on carcass quality and composition attributes for pork from lean yield and meat quality sire lines.Materials and MethodsBoars from a meat quality line (MQL) and a lean yield line (LYL) were mated to females from a commercial swine genetics company. Pigs were farrowed, weaned, and processed according to a typical industry protocol at the University of Georgia Swine research unit. As the pigs reached approximately 23 kg, three pigs from each gender within a litter were selected and randomly assigned a slaughter weight of 113, 136, or 159 kg. When the pigs reached their assigned slaughter weight, they were harvested at The University of Georgia Meat Science and Technology Center under inspection. A total of 151 pigs from 26 litters (13 per sire line) were evaluated. After carcasses were chilled for 24 h, carcass length was measured, and carcasses were then ribbed. Tenth rib back fat (TRBF), last rib back fat (LRBF), loin pHu, carcass muscle score (CMS), NPPC color and marbling scores, Hunter L*a*b*, loin eye area (LEA), and temperature were measured in the longissimus dorsi (LD). Primal and subprimal weights were collected and recorded from the fabricated carcass. Length, width, and depth (thickness) as well as firmness of the skinless belly was assessed. Samples were removed from the LD anterior to the 11thrib for proximate analysis, drip loss, Warner-Bratzler, and slice shear force collection. Data were analyzed using PROC MIXED procedures in SAS with the fixed effects of sire line, gender, and slaughter endpoint and their interactions. LSMEANS were generated and separated using LSD.ResultsBackfat thickness (TRBF and LRBF) was higher in MQL (P &lt; 0.01) than LYL, and lower in females (P &lt; 0.01) than males. The LYL had a greater LEA (P &lt; 0.01) than MQL, and females had a larger LEA (P &lt; 0.01) than males. Marbling and firmness scores (NPPC) were greater in MQL (P &lt; 0.01) than in LYL. As a percent of carcass weight, loin and ham weights were higher for LYL (P &lt; 0.01) than MQL; however, belly weight was greater for MQL (P &lt; 0.01) when compared to LYL. Belly dorsal firmness was greatest in MQL lines with slaughter weight of 159 kg (P &lt; 0.01). Belly dimensions increased (P &lt; 0.01) as slaughter weight increased. Proximate analysis of the LD showed that lipid content was higher (P &lt; 0.01) and moisture content was lower (P &lt; 0.01) in the MQL compared to LYL. Protein levels of the LD were lower from pigs slaughtered at 113 kg (P &lt; 0.01) than both 136 kg and 159 kg. Shear force, by both measurements, was lower in chops from pigs slaughtered at 113 kg (P &lt; 0.01) compared to those slaughtered at 136 and 159 kg. Percent fat free lean was greater (P &lt; 0.01) in LYL, females, and pigs slaughtered at 113 kg compared to MQL, males, and pigs slaughtered at 136 and 159 kg, respectively.ConclusionOverall, there were meat quality advantages for the MQL, but they occurred at the expense of yield, where LYL is superior. Increasing slaughter weights increased primal and subprimal weights and reduced lean yield but had little effect on carcass quality.

A genetic evaluation of growth, ultrasound, and carcass traits at alternative slaughter endpoints in crossbred heavy lambs.

Genetic parameters were estimated for growth, ultrasound, and carcass traits in a Canadian crossbred heavy lamb population. Traits analyzed included birth, weaning, post-weaning, and ultrasound scanning weights; pre- and post-weaning average daily gain; ultrasonically measured eye muscle and fat depths; hot carcass weight; fat depth at the GR site (110 mm from the midline on the 12th rib); carcass conformation scores; saleable meat yield; price grid value; and total carcass value. The impact of three alternative slaughter endpoints (slaughter age, carcass weight, and carcass fatness) on genetic parameter estimates was also evaluated. In general, carcass traits were found to be moderately heritable, with heritability estimates ranging from 0.17 ± 0.02 for hot carcass weight at a constant slaughter age to 0.34 ± 0.02 for average carcass conformation score at a constant carcass weight. Heritability estimates were similar when observations were adjusted to alternative slaughter endpoints, but for some traits, phenotypic variance and genetic correlation estimates differed. Genetic correlations between carcass traits and growth and ultrasound traits were typically favorable. Ultrasonically measured eye muscle depth and fat depth were found to be moderately to strongly positively correlated with hot carcass weight (0.33 ± 0.15 to 0.71 ± 0.19) and fat depth at the GR site (0.38 ± 0.14 to 0.74 ± 0.12), respectively, reaffirming the usefulness of selection on ultrasound traits to improve carcass yield and quality. Genetic correlations among carcass traits were generally favorable, with the exception of moderate unfavorable positive genetic correlations between fat depth at the GR site and primal cut carcass conformation scores (0.31 ± 0.05 to 0.60 ± 0.05). Overall, the results of this research suggest that there is potential to improve carcass yield and quality through genetic selection and provides the population-specific genetic parameter estimates needed for the genetic evaluation of carcass traits in the Canadian sheep population. Nevertheless, the optimal endpoint for carcass trait genetic evaluations will need to be further investigated, considering both the current findings and additional information on production practices in the industry.

627 BeefTrader: Optimal economical endpoint decision support system for feedlots and meat packers

This study aimed to identify the most profitable feeding endpoint for feedlot cattle based on each individual animal's optimal economical endpoint (OEE) using the BeefTrader Decision Support System (DSS). The hypothesis was that the traditional slaughter endpoint (TSE, currently used in commercial feedlots) would have different profitability than the OEE which is determined when the marginal net profit (MNV = daily change in revenue – expense) becomes negative. Using Monte Carlo simulations, MNV curves for 280 Nellore breed cattle were generated for 14 feedlots, using the Davis Growth Model reparametrized for Nellore. These simulated animals were sold by the model to 83 meat packers in Brazil. The constraints used were feedlot period ≥ 1 d, shrunk BW ≥ 390 kg, and empty body fat ≥ 16%. The optimized method considered the most suitable time for sale. From 280 animals simulated, 258 were sold by optimization process. The integrated MNV increased up to 74% (P < 0.05) for OEE compared to TSE. On average, an animal sold by OEE had a net profit of R$ 202.64 ± 6.35 (± SD) and for TSE R$ 116.54 ± 34.80. The variability of the animal's sale to OEE was significantly lower (about 3 times) in relation to the TSE, showing that BeefTrader can determine the time of slaughter based on both the chemical and physical body composition. At present, TSE is determined by visual inspection by trained technicians, resulting in greater variability and increased risk, since it is a non-optimized process. BeefTrader changes this scenario using an individual animal's dynamic growth and chemical composition, along with internal and exogenous economic information. The next step for this DSS is to be tested in a real farming situation, because the results presented here are encouraging. Acknowledgements: Grant #2015/07855-7 [BeefTrader PIPE Project and scholarships (16/02347-6; 16/02451-8; 16/07154-1; 16/12825-2; 16/12709-2)].

Fabrication yields of serially harvested calf-fed Holstein steers fed zilpaterol hydrochloride1

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.

고에너지 사양이 비육후기 거세한우의 성장, 도체, 및 혈액성상에 미치는 영향

The aim of this study was to examine the effects of high energy diet on growth 26mon, 28mon, and 30mon in Hanwoo at different ages. High energy diet required not only an amount of concentrate on days of fattening periods but also induced cost for the management. We hypothesized that high energy diet was able to reduce a fattening period to reach a certain quality grade. A 2 x 3 factorial arrangement (High energy, control vs 26, 28, 30month endpoints) in a completely random design was used to feed 48 Hanwoo steers. Four steers were fed in same pen and 12 pens were used for treatment. Blood was drawn from each steers on every other months during early, middle, and final fattening periods. Over all ADG and feed efficiency were not different between high energy and control diet (P > 0.05). Dry matter intake was induced 30 mo-old early and final fattening periods at high energy diet. Serum glucose concentration were increased (P < 0.05) at 30 and 26month old steers. Marbling scores were greater at 30 month old than 26 and 28 month old Hanwoo steers. Carcass weight of Hanwoo steers were greater at 30 mon-old groups than other groups. These result indicated that high energy diet (+3% TDN) and slaughter endpoint collectively contribute to the observed quality grade compositional differences among three final fattening periods of Hanwoo steers.

Effects of production system and slaughter weight endpoint on growth performance, carcass traits, and beef quality from conventionally and naturally produced beef cattle

Glanc, D. L., Campbell, C. P., Cranfield, J., Swanson, K. C. and Mandell, I. B. 2015. Effects of production system and slaughter weight endpoint on growth performance, carcass traits, and beef quality from conventionally and naturally produced beef cattle. Can. J. Anim. Sci. 95: 37–47. Effects of production system and slaughter endpoint on performance, carcass traits, and beef quality were investigated in 64 Simmental cross steers (minimum 75% Continental breeding). Cattle were allocated to: (1) conventional production system based on use of implants and dietary ionophores or (2) natural production system in which no implants or ionophores were used. Within each production system, cattle were allocated for slaughter at 545 or 636 kg liveweight. Steers were fed an 85.5% concentrate diet based on high-moisture corn, soybean meal, and alfalfa silage. Average daily gain tended to be greater (P&lt;0.06) in conventional production system cattle, while there was a trend (P&lt;0.08) for production system by endpoint interactions for dry matter intake and gain to feed. Natural production system cattle tended to have greater (P&lt;0.08) marbling and percent intramuscular fat (%IMF) with lower (P&lt;0.09) longissimus shear force, while production system by endpoint interactions were present (P ≤ 0.03) for%IMF and carcass lean composition via rib dissection. At-home consumer evaluation of longissimus muscle steaks found tenderness, juiciness, flavour, and overall acceptability rankings were greater (P&lt;0.01) for steaks slaughtered from heavier cattle (636 vs. 545 kg liveweight). Marketing cattle at lighter slaughter weights may have benefits for performance at the expense of eating quality.

Genetic Evaluation of Carcass Traits of Commercial Steers at Different Slaughter End–points

Genetic Evaluation of Carcass Traits of Commercial Steers at Different Slaughter End–points

Meat Quality Traits of Longissimus Muscle of Hanwoo Steers as a Function of Interaction between Slaughter Endpoint and Chiller Ageing

Carcass characteristics and meat quality traits as a function of endpoint months of slaughter age (26 vs 32 mon) and chillerageing (1 vs 10 d) were evaluated for m. longissmus of 26 Hanwoo steers fed with commercial diets including whole cropbarley silage. Totally twenty six Hanwoo steers for 6 mon of age that were fed until 26 mon of age constituted the short term-fed group and fed until 32 mon of age constituted long-term fed group. Carcasses were chilled for 24 h and were graded.Strip loin samples were divided into two age groups (1 d and 10 d). Long-term feeding increased carcass weight, rib-eyearea, yield grade, marbling score, firmness and quality grade of the meat. The feeding for 32 mon produced tender, juicymeat (p<0.01) with lower cooking loss and higher rating score (p<0.05) than short term feeding, while other quality traitswere not influenced by the length of feeding. Intramuscular fat content and oxidative stability (TBARS value) were signif-icantly (p<0.05) higher in beef from long-term feeding however the length of feeding did not alter the fatty acid composi-tion. Chiller aging reduced instrumental tenderness (WBSF value), improved color, sensory tenderness, acceptability andrating of beef. The results of the present study mirrors that Hanwoo steers until 32 mon of age overall improved carcass traitsand palatability compared to that for 26 mon. However, from the viewpoints of economical and environmental aspects, costof the additional feeding for 6 mon for value-adding of eating quality was relatively high and the effects in turn were limited . Key words: Hanwoo beef, barley-based diet, meat quality, length of feeding

Genetic Models for Carcass Traits with Different Slaughter Endpoints in Selected Hanwoo Herds I. Linear Covariance Models

Carcass characteristics data of Hanwoo (N = 1,084) were collected from two stations of the National Livestock Institute of Animal Science (NIAS), Korea and records from thirteen individual cow-calf operators were analyzed to estimate variance and covariance components and the effect of different slaughter endpoints. Carcass traits analyzed were cold carcass weight (CWT, kg), REA (rib eye area, cm 2 ), back fat thickness (mm) and marbling score (1-7). Four different models were examined. All models included sex and contemporary group as fixed effects and the animal's direct genetic potential and environment as random effects. The first model fitted a linear covariate of age at slaughter. The second model fitted both linear and quadratic covariates of age at slaughter. The third model fitted a linear covariate of body weight at slaughter. The fourth model fitted both linear covariates of age at slaughter and body weight at slaughter. Variance components were estimated using the REML procedure with Gibb's sampler. Heritability estimate of CWT was in the range of 0.08-0.11 depending on the model applied. Heritability estimates of BF, REA and MS were in the ranges of 0.23-0.28, 0.19-0.26, and 0.44-0.45, respectively. Genetic correlations between CWT and BF, between CWT and REA, and between CWT and MS were in the ranges of -0.33 - -0.14, 0.73-0.84, and -0.01-0.11, respectively. Genetic correlations between REA and BF, between MS and BF and between REA and MS were in the ranges of -0.82 ∼ -0.72, 0.04-0.28 and -0.08 ∼ -0.02, respectively. Variance and covariance components estimated varied by model with different slaughter endpoints. Body weight endpoint was more effective for direct selection in favor of yield traits and body weight endpoints affected more of the correlated response to selection for the traits of yield and quality of edible portion of beef.

Effects of grain source, silage level, and slaughter weight endpoint on growth performance, carcass characteristics, and meat quality in Angus and Charolais steers

Two growth performance trials were conducted to evaluate the effects of grain source (corn vs. barley), corn silage level (15 vs. 50%) and body weight (BW) at slaughter on growth performance, carcass characteristics, and beef quality. Gains were greater ( P &lt; 0.01) feeding corn vs. barley to Angus cattle slaughtered at 550 or 600 kg, most likely due to greater (P &lt; 0.02) feed intakes for corn-fed cattle. Despite greater dry matter intake (DMI; P &lt; 0.01) and feed to gain ratios (P &lt; 0.08) with 50% silage diets, cost of production was lower (P &lt; 0.01) feeding 50 vs. 15% silage diets. Grain source by BW endpoint interactions (P &lt; 0.06) were present for Angus steers due to greater average daily gain (ADG) and lower feed to gain and cost of production in corn-fed cattle slaughtered at 600 versus 550 kg, while the converse was the case for barley-fed cattle. Carcass characteristics and palatability attributes were generally not affected (P &gt; 0.05) by grain source or silage level in the diet. Grain source by silage level by slaughter endpoint interactions (P &lt; 0.08) were present for measures of tenderness (shear force and taste panel assessment of tenderness, chewiness, and rate of breakdown). Gains were not affected (P &gt; 0.27) by grain source for Charolais cattle, while barley feeding decreased (P &lt; 0.10) DMI, feed to gain, and costs of production versus corn feeding. Silage level in the diet did not affect (P &gt; 0.10) any growth performance trait in Charolais cattle. Grain source generally did not affect (P &gt; 0.10) most carcass characteristics and shear force with the Charolais steers. The feeding of the 15% silage diet decreased (P &lt; 0.10) measures of leanness and muscling. Many carcass characteristics were affected (P &lt; 0.02) by slaughter endpoint in Charolais steers, with values changing as BW at slaughter increased from 600 to 700 kg. Key words: Corn, barley, beef cattle, slaughter endpoint, shear force, palatability attributes

Estimadores de correlaciones genéticas para características de la canal de bovinos: efecto de diferentes criterios de sacrificio. Revisión

The objective of the present study was to analyze 532 estimates of genetic correlations for carcass traits of cattle published in the scientific literature from 1963 to 2003. The unweighted means, the ranges and the number of observations of the estimates of genetic correlations were calculated based on three different slaughter end points: age, weight and fat thickness. Estimates of genetic correlations for most pairs of traits varied greatly within each slaughter end point. For example, the range of ageconstant estimates of the genetic correlation between fat thickness and marbling score was from -0.42 to 1.00. Few studies have compared estimates of genetic correlations for carcass traits adjusted for different slaughter end points. Results from those few studies were inconsistent, although some studies revealed that estimates of genetic correlations for several combinations of carcass traits were sensitive to the covariate (slaughter end point) included in the model. Means of age-constant estimates of the genetic correlation between longissimus muscle area and marbling score, yield grade and predicted percentage of retail product were: 0.06, -0.79, and 0.59. These means suggest that selection for greater longissimus muscle area would improve yield grade and increase predicted percentage of retail product without altering marbling.

Genetic correlations between live yearling bull and steer carcass traits adjusted to different slaughter end points. 1. Carcass lean percentage1,2

We studied genetic relationships between age-constant live yearling beef bull growth and ultrasound traits and steer carcass traits with dissected steer carcass lean percentage adjusted to slaughter age-, HCW-, fat depth-, and marbling score-constant end points. Three measures of steer carcass lean percentage were used. Blue Tag lean percentage (BTLean) was predicted from HCW, fat depth, and LM area measurements. Ruler lean percentage (RulerLean) was predicted from carcass fat depth and LM depth and width measurements. Dissected lean percentage (DissLean) was based on dissection of the 10-11-12th rib section. Both BTLean (h2 = 0.30 to 0.44) and DissLean (h2 = 0.34 to 0.39) were more heritable than RulerLean (h2 = 0.05 to 0.14) at all end points. Genetic correlations among DissLean and RulerLean (rg = 0.61 to 0.70), DissLean and BTLean (rg = 0.56 to 0.72), and BTLean and RulerLean (rg = 0.59 to 0.90) indicated that these traits were not genetically identical. Adjusting Diss-Lean to different end points changed the magnitude, but generally not the direction, of genetic correlations with indicator traits. Ultrasound scan-age-constant live yearling bull lean percentage estimates were heritable (h2 = 0.26 to 0.42) and genetically correlated with each other (rg = 0.68 to 0.99) but had greater correlations with DissLean at slaughter age (rg = 0.24 to 0.48) and HCW (rg = 0.16 to 0.40) end points than at fat depth (rg = -0.08 to 0.13) and marbling score (rg = 0.02 to 0.11) end points. Scan-age-constant yearling bull ultrasound fat depth also had stronger correlations with DissLean at slaughter age (rg = -0.34) and HCW (rg = -0.25) than at fat depth (rg = -0.02) and marbling score (rg = -0.03) end points. Yearling bull scan-age-constant ultrasound LM area was positively correlated with DissLean at all endpoints (rg = 0.11 to 0.23). Genetic correlations between yearling bull LM method 1 width (rg = 0.38 to 0.56) and method 2 depth (rg = -0.17 to -0.38) measurements with DissLean suggested that LM shape may be a valuable addition to genetic improvement programs for carcass lean percentage at slaughter age, HCW, and fat depth constant end points. At all end points, steer carcass fat depth (rg = -0.60 to -0.64) and LM area (rg = 0.48 to 0.59) had stronger associations with DissLean than did corresponding live yearling bull measurements. Improved methods that combine live ultrasound and carcass traits would be beneficial for evaluating carcass lean percentage at fat depth or marbling score end points.

Genetic correlations between live yearling bull and steer carcass traits adjusted to different slaughter end points. 2. Carcass fat partitioning1,2

Partial carcass dissection data from 1,031 finished crossbred beef steers were used to calculate heritabilities and genetic correlations among subcutaneous, intermuscular, and body cavity fat percentage and marbling score adjusted to slaughter age-, HCW-, fat depth-, and marbling score-constant endpoints. Genetic correlations were also calculated among these fat partitions with live growth and ultrasound traits evaluated in yearling beef bulls (n = 2,172) and steer carcass measurements. Heritabilities of the different fat partitions ranged from 0.22 (marbling score-constant body cavity fat) to 0.46 (HCW-constant marbling score). Genetic correlations between subcutaneous fat and intermuscular fat (rg = 0.16 to 0.32) and between intermuscular fat and body cavity fat (rg = 0.38 to 0.50) were more highly associated than subcutaneous fat and body cavity fat (rg = -0.08 to 0.05), indicating that fat depots are not under identical genetic control. Adjusting fat depots to different end points affected the magnitude but usually not the sign of the genetic correlations. Bull postweaning gain was associated with intermuscular (-0.24 to -0.35), body cavity (-0.24 to -0.29), and marbling fat (-0.24 to -0.39) in steers. Bull hip height was associated with body cavity (-0.20 to -0.29) and marbling fat (-0.20 to -0.47) in steers. Bull ultrasound fat depth was associated with subcutaneous (0.11 to 0.29), intermuscular (0.05 to 0.36), body cavity (0.27 to 0.49), and marbling fat (0.27 to 0.73) in steers. Bull ultrasound intramuscular fat percentage was associated with subcutaneous (-0.22 to -0.44) and intermuscular fat (-0.06 to 0.31) in steers. Bull ultrasound LM area was associated with body cavity (-0.25 to -0.31) and marbling fat (-0.25 to -0.30) in steers. Ultrasound LM width measurements were negatively correlated with subcutaneous fat (rg = -0.09 to -0.18), intermuscular fat (rg = -0.53 to -0.61), body cavity fat (rg = -0.63 to -0.69), and marbling score (rg = -0.75 to -0.87) at slaughter age-, HCW-, and fat depth-constant endpoints; correlations were generally lower at a marbling score-constant end point (rg = 0.07 to -0.49). Ultrasound indicator traits measured in seedstock may be useful in altering fat partitioning in commercial beef carcasses.