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1.
In a 4-yr study, early-weaned Simmental steers (n = 192) of known genetics were individually fed to determine genetic, performance, and carcass factors explaining variation in carcass value and profitability. Steers were weaned at 88.0 +/- 1.1 d of age and pen-fed a high-concentrate diet (108.99 dollars/t) for 84.5 +/- 0.4 d before allotment. Calves were implanted with Synovex C at weaning and successively with Synovex S (Fort Dodge Animal Health, Fort Dodge, IA) and Revalor S (Intervet, Inc., Millsboro, DE). Steers consumed a 90% concentrate diet (98.93 dollars/t), consisting primarily of coarse cracked corn and corn silage, for 249.7 +/- 0.7 d and slaughtered at 423.3 +/- 1.4 d of age. Five-year price data were collected for feedstuffs, dressed beef, and grid premiums, and discounts. Average dressed beef price was 110.67 dollars/45.4 kg. Premiums (dollars/45.4 kg) were given for Prime (5.62 dollars), Average Choice (1.50 dollars), and yield grades (YG) 1 (2.46 dollars), 2A (1.31 dollars), and 2B (1.11 dollars). Discounts (dollars/45.4 kg) were given for Standard (-16.85 dollars), Select (-8.90 dollars), and YG 3A (-0.12 dollars), 3B (-0.19 dollars), 4 (-14.16 dollars), and 5 (-19.56 dollars). Discounts were given for HCW extremes as well (409 to 431 kg, -0.64 dollars; 432 to 454 kg -11.39 dollars; > 454 kg, -19.71 dollars). Input costs included annual cow costs (327.77 dollars), veterinary/medical and labor (35 dollars per animal), feed markup (22 dollars/t), yardage (0.25 dollars/d per animal), and interest (10%). Dependent variables were carcass value and profit per steer. Independent variables were year, weaning weight EPD, yearling weight EPD, marbling EPD, DMI, ADG, G:F, HCW, calculated YG, and marbling score (MS). Carcass value was correlated (P < 0.05) with yearling weight and marbling EPD, DMI, ADG, feed efficiency, HCW, and MS. Carcass weight, MS, and YG accounted for nearly 80% of the variation in carcass value among steers, explaining 51, 10, and 8%, respectively. Profit was correlated (P < 0.05) with DMI, ADG, feed efficiency, HCW, and MS. Carcass weight, MS, YG, and DMI accounted for nearly 78% of the variation in profit among steers, explaining 21, 18, 12, and 3%, respectively. Carcass weight was the most critical factor contributing to carcass value, whereas BW and carcass quality were the primary factors affecting steer profitability. These models represent the relative importance of factors contributing to value and profitability in early-weaned Simmental steers based on historical pricing scenarios.  相似文献   

2.
In a 4-yr study, early-weaned Simmental steers (n = 192) of known genetics were individually fed to determine EPD, performance, and carcass measurements explaining variation in carcass value and profitability across incremental days on feed (DOF) when sorted by HCW, calculated yield grade (YG), or at their highest profit endpoint (BEST). Steers were weaned at 88.0 +/- 1.1 d of age, pen-fed a high-concentrate diet for 84.5 +/- 0.4 d, individually fed for 249.7 +/- 0.7 d, and slaughtered at 423.3 +/- 1.4 d of age. Carcass weight, YG, and marbling score (MS) were predicted using real-time ultrasound throughout the finishing period to calculate carcass value and profitability at 90, 60, 30 d preslaughter and under three individual sorting strategies. Sorting strategies included marketing the 25 and 50% heaviest HCW, the highest YG at d 60 and 30, or the remaining 25% at 0-d endpoints. Independent variables were year, weaning weight EPD, yearling weight EPD, marbling EPD, DMI, ADG, HCW, YG, and MS. Profit was quadratic in response to increased DOF; the greatest economic return was noted on d 30 (pre-slaughter). Final weight, DMI, HCW, MS, and YG increased (linear; P < 0.001) with additional DOF, and ADG and G:F decreased (linear; P < 0.001). Total cost of gain was quadratic (P < 0.001), and incremental cost of gain rose at an increasing rate (quadratic; P < 0.001) with increased DOF. With increasing DOF, HCW importance decreased from 58 to 21%; MS was variable, ranging from 18 to 23%; and YG and DMI were minor contributors to profit variation. Among sorting strategies, final BW and HCW were greater for BEST, whereas other measurements were similar. Sorting individuals by HCW, YG, or at BEST increased profitability 3.70 dollars, 2.52 dollars, or 30.65 dollars over the optimal group DOF endpoint (d 30). Retrospective analyses illustrated that sorting does not need to pinpoint each animal's profit optimum to result in economic gains; rather, increasing HCW and decreasing weight- and YG-related penalties improved profitability. Opportunities may exist with existing and new technology to uniformly allocate cattle into feeding and marketing groups, decrease overfeeding, and increase carcass value and profitability.  相似文献   

3.
Steer progeny (n = 122) of tropically adapted breeds [Tuli (TU) and Brahman (BR)] and temperate breeds [Angus (AN) and Hereford (HP)] was evaluated for carcass traits for 3 yr. Multiparous British (Bt) cows were bred to each sire breed. Following weaning in the fall, steers were provided bermudagrass hay and a supplement until rye was available, which they grazed until March. Steers were fed for 100 to 110 d beginning in March. Live weight (LWT); hot carcass weight (HCW); longissimus area (LEA); percentage kidney, pelvic, and heart fat (KPH); actual fat thickness (ACT); adjusted fat thickness (ADJ); marbling score(MARB); maturity score(MAT); quality grade (QG); yield grade (YG); dressing percentage(DP); and LEA per unit of LWT (LEACWT) were collected. Data were analyzed by Proc MIXED using a model that included year, sire breed, and year × sire breed. Sire breed was a significant source of variation for all traits except LEA. The effect of year was significant for all traits, and year × sire breed was significant for only LWT. Least square means for LWT and HCW ranked the breeds similarly; the AN-sired calves (576 kg, 333 kg) and BR-sired calves (574 kg, 334 kg) were heavier than the TU-sired calves (526 kg, 304 kg), and the HP-sired calves had intermediate LWT and HCW (562 kg, 320 kg). The actual and adjusted fat means were larger (P<0.02) for AN-sired calves, HP-sired cavles were intermediate, and the BR- and TU-sired steers were similar with less external fat. The TU-sired calves had the largest LEA relative to weight. The AN- and TU-sired groups had a similar percentage grading Choice (26 and 21%, respectively), and the percentage grading Choice for the other two sire breed groups was 12% for BR and 18% for HP. In conclusion, carcass merit of TU-sired calves provides an acceptable alternative to BR-sired calves for producers desiring a tropically adapted sire breed, but they will likely produce smaller slaughter BW than BR sires if managed similarly.  相似文献   

4.
To evaluate effects of previous forage systems on feedlot performance, yearling Hereford steers (average initial weight of 249 kg) were grazed on tall fescue (TF), smooth bromegrass-red clover (BG-RC) or orchardgrass-red clover (OG-RC) pastures before finishing. Serial slaughter was utilized during the first 2 yr of this study to determine changes in carcass characteristics throughout finishing, while steers were slaughtered at approximately 29% body fat during the third year. Steers grazing TF entered the feedlot at lighter weights and maintained lighter weights throughout finishing (P less than .05) even though dry matter intakes and feed conversions were similar (P greater than .05) among treatments. Steers that previously grazed TF had less (P less than .05) body fat, body protein, fat thickness and marbling, smaller (P less than .05) ribeye areas and lower (P less than .05) USDA yield and quality grades than than those that grazed BG-RC and OG-RC. However, linear contrasts indicated that steers grazing TF were compensating in ribeye area, marbling and quality grade as days in feedlot increased. This was confirmed in the third-year study, since carcass characteristics were similar among all steers. During the third year, linear and quadratic contrasts indicated that steers that grazed TF partially compensated in body protein. As days in feedlot increased, live and hot carcass weights, body fat, fat thickness, kidney, pelvic and heart fat, marbling, and USDA yield and quality grades increased (P less than .05), while ribeye area and body protein plateaued. Although carcass characteristics were similar among treatments, steers backgrounded on TF entered the feedlot at lighter weights, and partially compensated in weight after 134 d of finishing.  相似文献   

5.
The objective of this study was to evaluate the effect of growth implants on the carcass characteristics and tenderness of steers and heifers with different genetic potentials for growth, lean meat yield production, and marbling. Two experiments were conducted. Experiment 1 evaluated Angus steers sired by bulls with high EPD for retail product yield or marbling. Implant treatment was imposed randomly within sire groups. Loins (Institutional Meat Purchasing Specifications 180) were collected from each carcass and cut into three 2.54-cm steaks aged for 7, 14 and 21 d to evaluate tenderness. The second experiment evaluated steers and heifers of British and Continental breed descent. Steers and heifers were slaughtered after 120 d on feed. Loin sections were collected, and one 2.54-cm steak aged 7 d was used for tenderness analysis. When implants were used in Angus steers, HCW and LM area increased, whereas internal fat and marbling decreased (P < 0.01). In Angus steers, sire type did not affect shear force values of steaks; however, implant use significantly increased shear force values (P < 0.01). Carcasses from cattle of Continental breed descent were significantly heavier than carcasses of British breed descent with larger LM area, slightly less fat, and a reduced yield grade (P < 0.01). Also, steer carcasses were heavier than heifer carcasses with larger LM (P < 0.05), but no effect of sex on fat depth, internal fat, yield grade or marbling was observed. No significant interactions were seen between growth implant and breed or between growth implant and sex for shear force values. Shear force values were significantly less for steaks from steers and heifers of British decent compared with steers and heifers of Continental descent (P < 0.01). Steaks from implanted steers and heifers had significantly (P < 0.01) greater shear force values than steaks from steers and heifers not implanted. Use of growth implants in growing cattle resulted in significantly heavier carcass weights, larger LM area, and reduced internal fat. However, implant use also reduced the amount of marbling along with contributing to reduced tenderness. Complicating the tenderness issue is the increased shear force values reported for heifers as well as steers of Continental breed descent. Use of implants may contribute to tenderness variability because of different animal responses to implants.  相似文献   

6.
Although several previous studies have identified associations between cattle carcass characteristics and various SNP, comparatively little work has sought to validate the marker panels currently sold and marketed by commercial genotyping companies. Panels typically use a handful of SNP, but these range from as few as 2 to more than 100. Data from 764 commercially fed steers and heifers were used to assess the relationships of growth and carcass traits and Igenity panel scores for ADG, marbling (or percentage of USDA Choice), rib-eye area (REA), tenderness, fat thickness, and USDA Yield grade (YG). Results revealed statistically significant, but low, correlations between carcass measurements and corresponding Igenity panel scores. Genetic correlations were computed among the various Igenity panels and demonstrated either that several common markers existed across the panels or that markers across panels were in high linkage disequilibrium. Across all breeds, the genotypic correlations between the Igenity panel scores for ADG, REA, marbling, and YG with observed ADG, REA, USDA Quality grade, and YG at slaughter were 0.51, 0.38, 0.63, and 0.59 (P < 0.01), respectively. The partial effects of the Igenity marbling panel persisted in a multivariate regression model. Net return was significantly affected only by marbling panel score; a 1-unit increase in marbling panel score increased the net return by an estimated $7.53 per animal.  相似文献   

7.
British and British x Continental steers (n = 560; initial BW = 339.4 +/- 1.76 kg) were used in a serial slaughter study with a completely random design to evaluate effects of zilpaterol hydrochloride (ZH; 8.33 mg/kg of dietary DM basis) on performance and carcass characteristics. Treatments were arranged in a 4 x 4 factorial (112 pens; 7 pens/treatment; 5 steers/pen) and included duration of ZH feeding (0, 20, 30, or 40 d before slaughter plus a 3-d ZH withdrawal period) and days on feed (DOF) before slaughter (136, 157, 177, and 198 d). No duration of ZH feeding x slaughter group interactions were detected for the performance measurements (P > 0.10). Final BW did not differ (P = 0.15) between the 0-d group and the average of the 3 ZH groups, but ADG was greater for the average of the 3 ZH groups during the period in which ZH diets were fed (P < 0.01) and for the overall feeding period (P = 0.05). As duration of ZH feeding increased, DMI decreased (P = 0.01) and G:F increased linearly (P < 0.01). With the exception of KPH (P = 0.022), no duration of ZH feeding x slaughter group interactions (P > 0.10) were detected for carcass characteristics. Regardless of the duration of ZH feeding, cattle fed ZH had greater HCW (P < 0.01), greater dressing percent (P < 0.01), less 12th-rib fat (P < 0.01), larger LM area (P < 0.01), less KPH (P = 0.03), and lower yield grade (P < 0.01) than the 0-d cattle. The 0-d group had greater marbling scores (P < 0.01) than cattle fed ZH diets, with a tendency for a linear decrease in marbling score (P = 0.10) as duration of ZH feeding was extended. A greater percentage of carcasses in the 0-d group graded USDA Choice or greater (P < 0.01) than in the 3 ZH groups, whereas the percentage of Select carcasses was greater (P = 0.01) for the 3 ZH groups. From d 0 to end (P = 0.04) and during the last 43 d on feed (P < 0.01), ADG responded quadratically to DOF before slaughter. No differences were detected among slaughter groups for DMI for the entire trial period; however, a quadratic response (P = 0.02) was observed for the final 43 d before slaughter. A quadratic response was also detected for the final 43 d before slaughter (P < 0.01) and from d 0 to end (P = 0.02) for G:F. Final BW, HCW, dressing percent, and 12th-rib fat increased linearly (P < 0.01) as DOF before slaughter increased. Our results indicate that no substantial effects on performance and carcass measurements were observed when ZH was fed for 30 or 40 d as opposed to 20 d, and that effects of ZH generally did not interact with DOF before slaughter.  相似文献   

8.
One hundred-sixty Holstein growing-finishing steers (initial BW of 185 kg) were blocked by BW to determine the effectiveness of long-term bovine somatotropin (bST) administration on lean, skeletal, and carcass measurements. Steers were randomly allocated to 4 treatments (10 steers/treatment) within a block (n = 4 blocks). Treatments were control, no bST (C-C); bST from d 0 to 182 (bST-C); bST from d 183 to slaughter (C-bST); and bST from d 0 to slaughter (bST-bST). Steers received a s.c. injection of placebo or bST at 14-d intervals. Doses were 320 mg of bST/injection from d 0 to 112 and 640 mg of bST/injection from d 113 to slaughter. The last treatment was administered 31 d before slaughter. Steers received a 14% CP (DM basis) diet from d 0 to 182 and 11.5% CP from d 183 to slaughter that consisted of dry, whole-shelled corn and a pelleted protein-mineral supplement. Steers were slaughtered when BW per block averaged 615 kg (d 325, 353, 367, and 381 for the 4 blocks, respectively). Thirty steers were removed from the study because of poor performance with respect to their pen mates, illness, lameness, death, incomplete castration, and incorrect treatment. Serum IGF-I concentrations increased 151% (P < 0.01) from d 7 through 35 in bST-treated steers compared with control steers. During the first 182 d, bST-C and bST-bST steers were heavier (P < 0.01) and had greater (P < 0.01) ADG, G:F, hip height, and hip height gain compared with C-C and C-bST steers. From d 183 to slaughter, C-bST steers had reduced (P < 0.05) daily DMI and greater G:F than bST-C steers. At final slaughter, C-bST and bST-bST steers had greater (P < 0.05) hip height than C-C steers. Noncarcass weight was increased and dressing percent reduced (P < 0.05) in C-bST and bST-bST steers compared with C-C steers. Quality grade was least (P < 0.05) in bST-bST carcasses compared with C-C, whereas bST-C and C-bST carcasses were intermediate. At final slaughter, steers receiving bST had greater (P < 0.05) carcass protein and water composition and lower (P < 0.05) carcass lipid and lipid accretion than C-C steers. Bovine somatotropin was effective in reducing carcass fat and increasing edible lean. Administering bST to young, lightweight steers increased skeletal growth and noncarcass weight without an increase in total carcass weight, but decreased carcass quality.  相似文献   

9.
Carcasses of 342 steers of known genetic backgrounds from four fundamentally different growth types were developed either on pasture or feedlot regimens to study differences in carcass traits. Growth types were large framed-late maturing (LL), intermediate framed-intermediate maturing (II), intermediate framed-early maturing (IE), and small framed-early maturing (SE). Five calves from each growth type were assigned to each regimen in each year of a 9-yr study. Eighteen steers were removed from the study because of accident or illness. Data collected were preslaughter shrunk BW (SBW); hot carcass weight (HCW); chilled carcass weight (CCW); dressing percentage (DRESS); fat thickness at the 12th and 13th-rib interface (FAT); percentage kidney, pelvic, and heart fat (KPH); longissimus muscle area (LMA); marbling score (MARB); quality grade (QG); and yield grade (YG). Differences in carcass traits reflected genetic differences among growth types. The LL steers had heavier BW, HCW, and CCW and larger LMA (P < .05) than steers of other growth types, regardless of development regimen. Among pasture-developed steer carcasses, IE and SE steers had higher (P < .05) MARB and QG than either LL or II steers. Carcasses of large framed-late maturing steers had the lowest (P < .05) MARB and QG of the growth types. Carcasses of the II, IE, and SE steers had a higher (P < .05) numerical value for YG than carcasses of the LL steers. Among the carcasses of the feedlot-developed steers, IE and SE steers had the highest (P < .05) MARB and QG. Carcasses from the IE and SE steers were fatter (P < .05) than those from LL or II steers. Carcasses of the LL steers had the lowest percentage of KPH of growth types developed in the feedlot. No difference was observed in KPH for carcasses of II, IE, and SE steers. The LL steer carcasses had the lowest numerical value for YG of all growth types. These data indicate that variation existed among carcass traits for the four growth types and that carcass traits influenced by fatness were greater and more attainable in the feedlot-developed steers using current methods of evaluation.  相似文献   

10.
Sixty-three Angus x Simmental calves were allotted to a bull or a steer group based on sire, birth date, and birth weight to determine effects of castration status on performance, carcass characteristics, and circulating insulin-like growth factor I (IGF-I) concentrations in early-weaned cattle. At 75 d of age, calves in the steer group were castrated. Calves were not creep-fed prior to weaning. All calves were weaned and weighed at an average age of 115 d and transported by truck to the OARDC feedlot in Wooster, OH. Performance and carcass characteristics were measured in three phases. Phase 1 was from 115 to 200 d of age, phase 2 was from 201 to 277 d of age, and phase 3 was from 278 d of age to slaughter. Before implantation, four bulls and four steers were selected for serial slaughter and carcass evaluation. Steers were implanted with Synovex-C at 130 d of age and with Revalor-S at 200 and 277 d of age. Serum samples were collected from all calves on the day of implantation, 28 and 42 d after implantation, and at slaughter and analyzed for circulating IGF-I concentration. Bulls gained 9.7% faster (1.75 vs 1.60 kg/d; P < 0.01), consumed 25 kg more DM (521 vs 496 kg; P = 0.11), and were 3.3% more efficient (282 vs 273 g/kg, P < 0.10) than steers in phase 1. However, steers gained 10.5% faster (1.62 vs 1.46 kg/d; P < 0.02), consumed similar amounts of DM, and were 6.5% more efficient than bulls (214 vs 201 g/kg; P < 0.06) in phase 2. Overall gains and efficiency were similar between bulls and steers; however, bulls consumed 140 kg more DM (P < 0.05), were 27 kg heavier (P < 0.05), and had to stay in the feedlot 18 more days (P < 0.05) than steers to achieve a similar amount of fat thickness. Implanted steers had greater concentrations of circulating IGF-I than bulls (P < 0.01), and the pattern of IGF-I concentration over time was affected by castration status (castration status x time interaction; P < 0.01). Synovex-C had a lower impact on circulating IGF-I concentration (implant effect, P < 0.01) than either Revalor-S implant. Eighty-five percent of both bulls and steers had marbling scores sufficient to grade low Choice or better. Bulls achieved their target fat thickness later, increased muscle growth, and deposited fat more favorably than steers, possibly due to a gradual increase in IGF-I concentration as the testicles grew rather than the large fluctuations in IGF-I concentration observed in steers following implantation.  相似文献   

11.
The objective of this study was to characterize breeds representing diverse biological types for postweaning growth and carcass composition traits in terminal crossbred cattle. Postweaning growth and carcass traits were analyzed on 434 steers and 373 heifers obtained by mating F1 cows to Charolais sires. Maternal grandsires represented Hereford, Angus, and MARC III (1/4 Hereford, 1/4 Angus, 1/4 Pinzgauer, and 1/4 Red Poll) dams to Hereford or Angus (British Breeds), Norwegian Red, Swedish Red and White, Wagyu, or Friesian breeds. Breed groups were slaughtered serially in each of 2 yr (2002 and 2003). Postweaning ADG, slaughter weight, hot carcass weight, dressing percentage, percentage Choice, LM area, marbling score, USDA yield grade, fat thickness, retail product yield (percentage), retail product weight, fat yield (percentage), fat weight, bone yield (percentage), and bone weight were analyzed. Maternal grandsire breed was significant (P < 0.05) for all traits except dressing percentage, percentage Choice, and LM area. Marbling score for animals with Norwegian Red, Wagyu, Swedish Red and White, British Breeds, and Friesian inheritance was 550, 544, 532, 530, and 515, respectively (SEM = 8). Retail product weight for these animals was 224, 211, 227, 223, and 223 kg, respectively (SEM = 2 kg). Maternal granddam breed was not significant for any of the traits analyzed. Grandsire breed effects can be optimized by selection and use of appropriate crossbreeding systems.  相似文献   

12.
A 2(3) factorial arrangement of treatments was utilized to determine effects of postweaning zeranol implantation, breed (Angus vs Limousin) and castration (bull vs steer) on growth, behavior and carcass traits. An initial slaughter group was used to account for breed differences in composition and to determine fat and lean growth in the 9-10-11th rib section (NTE). The remaining cattle were fed a finishing diet to a fat end point of .76 cm, as determined by a backfat probe. Control bulls outgained (P less than .01) control steers both to the first kill date and over the entire test and did not require significantly more time to reach the fat end point. The implant did not influence gain in bulls but did increase gain in steers. Angus and Limousins were similar in growth rate for the first 126 d before the first slaughter date. Limousins required more (P less than .01) time to reach the fat end point. Bulls and Limousins produced heavier (P less than .01) carcasses and larger rib eyes (P less than .05; bulls; P less than .01; Limousins). Steers and Angus had higher (P less than .01) marbling scores and lower bone maturity. Implanting decreased (P less than .05) marbling and increased carcass maturity. Small but significant shifts in carcass wholesale cut weight distribution were found between breed and sex condition groups. Bulls and Limousins had greater lean growth in the NTE. Bulls and steers were similar in fat growth, but Angus exceeded Limousin in this trait. Zeranol reduced scrotal circumference (P less than .01) and testicle weight at slaughter (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
The objectives of this work were to estimate heterosis and breed genetic effects for carcass quantity, quality, and palatability traits of steers (Bos spp.) produced from matings of Romosinuano, Brahman, and Angus cattle. Steers (n = 464) were weaned at 7 mo of age and transported to the Southern Great Plains where they grazed winter wheat for 6 mo and were then fed a finishing diet until serial slaughter after different days on feed (average 130 d). Carcass quality and quantity traits were measured; steaks (aged 7 d) were obtained for palatability evaluation. Heterosis was detected for BW, HCW, dressing percentage, LM area, and yield grade for all pairs of breeds. Generally, Romosinuano-Angus heterosis estimates were smallest, Romosinuano-Brahman estimates were intermediate, and Brahman-Angus heterosis estimates were largest. The direct Romosinuano effect was to decrease (P < 0.05) BW (-67 ± 16 kg), HCW (-48 ± 10 kg), dressing percentage (-1.4 ± 0.5 units), 12th rib fat thickness (-5.2 ± 0.8 mm), and yield grade (-0.9 ± 0.1), and to increase LM area per 100 kg HCW (3.6 ± 0.3 cm(2)/100 kg). Significant Brahman direct effects were detected for BW (34 ± 17 kg), HCW (29 ± 10 kg), dressing percentage (1.6 ± 0.6 %), LM area per 100 kg HCW (-3.3 ± 0.4 cm(2)/100 kg), and yield grade (0.6 ± 0.1). Significant Angus direct effects were to increase 12th rib fat thickness (3.8 ± 1 mm). Among sire breed means, Romosinuano had reduced (P = 0.002) marbling score (393 ± 9) than Angus, but greater mean sensory tenderness scores (5.8 ± 0.1), and reduced percentage Standard carcasses (10 ± 2%) than Brahman (P < 0.002). Angus sire breed means for marbling score (475 ± 10), overall tenderness (5.8 ± 0.1), and percentage Choice carcasses (75 ± 5%) were greater (P < 0.05) than Brahman sire breed means (360 ± 11, 5.4 ± 0.1, 31 ± 5%). From consideration only of characteristics of the end product of beef production, Romosinuano did not provide a clearly superior alternative to Brahman for U.S. producers, as they had some quality and palatability advantages relative to Brahman, but at lighter HCW.  相似文献   

14.
Effects of ractopamine hydrochloride (RAC) supplementation on growth performance and carcass characteristics of feedlot steers differing in biological type were investigated using British, Continental crossbred, and Brahman crossbred calf-fed steers (n = 420). Steers of each type were weighed at reimplantation [British, mean BW = 375 kg (SD = 38 kg); Continental crossbred, mean BW = 379 kg (SD = 42 kg); Brahman crossbred, mean BW = 340 (SD = 32 kg)] and sorted into 7 BW blocks, each block consisting of 2 pens (10 steers per pen) per type. Pens within a block x type subclass were randomly assigned to RAC treatments (0 or 200 mg x steer(-1) x d(-1) fed during the final 28 d of the finishing period). The type x RAC interaction did not affect (P > 0.05) any of the traits evaluated in this study. Feeding RAC improved (P = 0.001) ADG (1.50 vs. 1.73 +/- 0.09 kg) and G:F (0.145 vs. 0.170 +/- 0.005), but did not affect (P = 0.48) DMI of steers. Dressing percentage, adjusted fat thickness, KPH percentage, and yield grade were not affected by RAC supplementation. Carcasses of steers fed RAC had heavier (P = 0.01) HCW (359 vs. 365 +/- 4.9 kg), larger (P = 0.046) LM areas (81.7 vs. 84.0 +/- 1.1 cm(2)), and tended (P = 0.07) to have lower mean marbling scores (487 vs. 477 +/- 5.2; Slight = 400, Small = 500) than did carcasses of control steers. Among the 3 biological types, Brahman crossbred steers had the lowest DMI and produced the lightest-weight carcasses that had the lowest mean marbling score (P < 0.05). Compared with Continental crossbred and Brahman crossbred steers, British steers produced carcasses with the greatest (P = 0.001) mean marbling scores. Continental crossbred steers had the heaviest BW and greatest dressing percentages and produced the heaviest carcasses with the largest LM areas (P < 0.05) compared with British and Brahman crossbred steers. In the present study, 28 d of supplementation with RAC at a dosage rate of 200 mg x steer(-1) x d(-1) elicited consistent responses in growth performance and carcass traits among 3 diverse biological cattle types.  相似文献   

15.
The impact of respiratory disease during a 150-d feedlot finishing period on daily gain, carcass traits, and longissimus tenderness was measured using 204 steer calves. Feedlot health status was monitored in two ways. First, clinical signs of respiratory infection were evaluated each day; treatment with antibiotic was based on degree of fever (if rectal temperature exceeded 40 degrees C then calves were treated). Steers that were treated (n = 102) had lower (P<.05) final live weights, ADG, hot carcass weights (HCW), less external and internal fat, and more desirable yield grades. Steers that were treated had a higher prevalence of carcasses that graded U.S. Standard than steers that were never treated. Second, as an alternative index of health status, lungs of all steers were evaluated at the processing plant using a respiratory tract lesion classification system; this health index included presence or absence of preexisting pneumonic lesions in the anterioventral lobes plus activity of the bronchial lymph nodes (inactive vs active). Lung lesions were present in 33% of all lungs and were distributed almost equally between treated (37%) and untreated cattle (29%). Steers with lesions (n = 87) had lower (P<.05) daily gains, lighter HCW, less internal fat, and lower marbling scores than steers without lesions. Compared to steers with lesions but inactive bronchial lymph nodes (n = 78), steers with lung lesions plus active lymph nodes had lower (P<.01) ADG and dressing percentage. Longissimus shear force values for steaks aged 7 d were lower (P = .05) from steers without lung lesions than those for steaks from steers with lung lesions. Overall, morbidity suppressed daily gains and increased the percentage of U.S. Standard carcasses. Compared to health assessment by clinical appraisal (based on elevated body temperature), classification based on respiratory tract lesions at slaughter proved more reliable statistically and, thereby, more predictive of adverse effects of morbidity on production and meat tenderness.  相似文献   

16.
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.  相似文献   

17.
It is well established that grazing Neotyphodium coenophialum-infected forages results in reduced BW gain and serum prolactin concentrations of cattle. The objective of this study was to determine the potential effects of toxic endophyte-infected tall fescue consumption on blood metabolites, carcass characteristics, and content of proteins critical for AA metabolism in the liver, kidney, and LM tissue of growing steers. Steers grazed a low toxic endophyte (LE; 0.023 microg/g ergot alkaloids) tall fescue-mixed grass pasture (n = 9; BW = 266 +/- 10.9 kg; 5.7 ha) or a high toxic endophyte (HE; 0.746 microg/g of ergot alkaloids) tall fescue pasture (n = 10; BW = 267 +/- 14.5 kg; 5.7 ha) from June 14 through at least September 11 (> or =89 d). No difference was observed for BW (P < 0.10) for the overall 85-d growth period. Also, no differences were observed for ribeye area/100 kg of HCW (P > 0.91), backfat (P > 0.95), or backfat/100 kg of HCW (P > 0.67). However, ADG (P < 0.01), final BW (P < 0.05), HCW (P < 0.01), dressing percentage (P < 0.01), ribeye area (P < 0.01), whole liver wet weight (P < 0.01), and whole liver wet weight/100 kg of end BW (P < 0.01) were greater for LE steers than HE steers. After 85 d of grazing, serum concentrations of alkaline phosphatase (P < 0.05), alanine aminotransferase (P < 0.01), aspartate aminotransferase (P < 0.03), cholesterol (P < 0.01), lactate dehydrogenase (P < 0.01), and prolactin (P < 0.01) were less for HE than LE steers. At slaughter, hepatic content of cytosolic phosphoenolpyruvate carboxykinase (P < 0.01) was greater in HE steers than LE steers. Hepatic content of aspartate aminotransferase (P < 0.01) also was greater, whereas renal and LM content were not (P > or = 0.42). No differences (P > or = 0.15) were observed for hepatic, renal, and LM content of alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase, and 3 glutamate transport proteins. These data indicate that the HE steers displayed classic endophyte toxicity symptoms for growth and blood variables, classic symptoms that were concomitant with novelly identified altered glucogenic capacity of the liver and decreases in carcass characteristics.  相似文献   

18.
Twenty-four beef steers (predominantly Angus x Hereford, 14 to 18 mo of age, 403 +/- 3 kg of BW), were housed and fed in individual pens for about 122 d. Twelve steers came from a herd that had been selected for growth (high growth; HG) and the other 12 from a herd with no selection program (low growth; LG). Another 6 steers (3 from each group) were slaughtered at the beginning to obtain the initial composition. All steers were fed the same corn-based diet (3.06 Mcal of ME/kg of DM, 13.6% CP) on an ad libitum basis. Two weeks before slaughter, total urine was collected for 5 d for estimation of 3-methylhistidine excretion and myofibrillar protein breakdown rates. Compared with LG steers, HG steers had less initial BW but greater final BW, DMI (7.52 vs. 6.37 kg/d), ADG (1.33 vs. 0.853 kg/d), G:F (0.176 vs. 0.133 kg/kg), ME intake (0.233 vs. 0.201 Mcal x kg of BW(0.75) x d(-1)), and retained energy (RE; 0.0711 vs. 0.0558 Mcal x kg of BW(0.75) x d(-1)); gained more fat (676 vs. 475 g/d); and tended to gain more whole body protein (100 vs. 72 g/d), with no difference in residual feed intake (RFI). Estimated net energetic efficiency of gain (k(g)) and ME for maintenance (ME(m)) did not differ between the 2 groups, averaging 0.62 and 0.114, respectively. The HG steers had greater HCW (350 vs. 329 kg), backfat (16.1 vs. 11.6 mm), and yield grades (3.53 vs. 2.80), with a similar dressing percent, KPH fat, LM area, and marbling score. Skeletal muscle protein gain (70.2 vs. 57.6 g/d) and fractional protein accretion rate (0.242 vs. 0.197%/d) tended to be greater in HG than in LG steers. Steers were classified into low (-0.367 kg/d) and high (0.380 kg/d) RFI classes. Compared with the high RFI steers, low RFI steers consumed less DM (6.61 vs. 7.52 kg/d) and ME (0.206 vs. 0.234 Mcal x kg of BW(0.75) x d(-1)) and tended to gain less fat (494 vs. 719 g/d), but were similar for initial and final BW, ADG, G:F, protein gain, HCW, dressing percent, backfat, KPH fat, LM area, marbling score, and yield grade, as well as for all observations related to myofibrillar protein metabolism. Residual feed intake may be positively [corrected] correlated with ME for maintenance. The maintenance energy requirement increased by 0.0166 Mcal x kg(-0.75) x d(-1) for each percentage increase in fractional protein degradation rate, confirming the importance of this process in the energy economy of the animal.  相似文献   

19.
Seventy-three crossbred steers (initial BW = 170.5 +/- 5.5 kg) from The Ohio State University (Exp. 1) and 216 crossbred steers (initial BW 135.4 +/- 4.4 kg) from the University of Illinois (Exp. 2) were used to determine the effect of source of energy and rate of growth on performance, carcass characteristics, and glucose and insulin profiles on early-weaned steers. Effects of the diets used in Exp. 1 and 2 on ruminal pH and VFA concentrations were quantified using ruminally fistulated steers (Exp. 3). Cattle were weaned at an average age of 119 d in all experiments and were allotted by age, BW, and breed to one of four diets: high-concentrate, fed ad libitum (ALCONC), high-concentrate fed to achieve a gain of either 1.2 kg/d (1.2CONC) or 0.8 kg/d (0.8CONC), or high-fiber, fed ad libitum (ALFIBER). At 218 d of age, all steers were placed on the ALCONC diet until slaughter. Steers were implanted with Compudose at the initiation of all experiments and with Revalor-S when they were estimated to be 100 d from slaughter. When steers in Exp. 1 averaged 181 and 279 d of age, serum samples were collected to determine glucose and insulin concentrations. Steers were slaughtered when a fat thickness of 1.27 cm was reached (Exp. 1) or after 273 d on feed (Exp. 2). In Exp. 1, days in the feedlot (P < 0.01) and age at slaughter (P < 0.01) were lowest for ALCONC and ALFIBER steers, and greatest for 0.8CONC steers. Overall, ADG was greatest for ALCONC and lowest for 0.8CONC steers; feed efficiency was lowest (P < 0.01) for ALFIBER steers. Final BW did not differ (P > 0.57) among treatments. At 181 and 218 d of age, serum insulin was increased (P < 0.10) and intramuscular fat percentage was greatest (P < 0.07), respectively, for ALCONC steers. In Exp. 2, overall ADG (P < 0.06) and final BW (P < 0.04) were greatest for ALCONC and lowest for 1.2CONC and 0.8CONC steers. Overall feed efficiency was greatest for 0.8CONC and lowest for ALFIBER (P < 0.01). Growing phase diet did not affect marbling score at 218 d of age or at slaughter (P > 0.81). In Exp. 3, differences in ruminal pH after feeding may have been a consequence of increasing acetate (ALFIBER), propionate (ALCONC), or a combination of VFA (0.8CONC and 1.2CONC), respectively (diet x time after feeding, P < 0.10). Controlling growth by limit-feeding a high-concentrate diet for only 100 d does not extend the growth curve of early-weaned steers or enhance intramuscular fat deposition at slaughter compared to ad libitum intake of a high-concentrate or high-fiber diet.  相似文献   

20.
Feedlot producers could optimize the value of cattle in a given market grid if they were able to improve the uniformity of the body composition between cattle among loads. Allelic variation due to a single nucleotide transition (cytosine [C] to thymine [T] transition that results in a Arg25Cys) has been demonstrated to be associated with higher leptin mRNA levels in adipose tissue and increased fat deposition in mature beef, but the effect on economically important carcass traits has not been investigated in either market-ready steers or heifers. Therefore, the objective of this study was to determine the effects of a leptin SNP on the quality grade (QG), yield grade (YG), and weight of beef carcasses. A slaughter trial was conducted using 1,435 crossbred finished heifers and 142 crossbred finished steers as they entered the slaughter facility. Canada QG tended (main effect of genotype P = 0.16, but P < 0.01 for both CC vs. TT and CT vs. TT) to be affected by leptin genotype. Specifically, 7.6 and 7.1% more TT carcasses graded Canada AAA or higher than the CT and CC carcasses, respectively, which supports the suggestion that the leptin SNP is associated with carcass fat. The proportion of carcasses grading Canada YG 1, 2, or 3 was affected (P < 0.01, P = 0.05, and P = 0.02 for YG 1, 2, and 3) by leptin genotype. The proportion of TT carcasses of Canada YG 1 was 12.5 and 15.1% lower than that of CT and CC carcasses, respectively, indicating that rearing animals under the same management and feeding system may result in greater carcass fat and a lower probability of the proportion of carcasses grading YG 1 within certain genotypes. The carcass weights of animals with the CC genotype tended (P = 0.07) to be higher than those of the TT genotype (365.5 vs. 362.3 kg). No significant difference was observed between the TT and CT genotypes in carcass weight. The observed associations between leptin genotype and carcass characteristics may represent an opportunity to genetically identify animals that are most likely to reach specific marketing groups.  相似文献   

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