Determination of the effect of brand and product identification on consumer palatability ratings of ground beef patties

The objective of this study was to determine the effect of brand and product identification on consumer palatability ratings of ground beef patties. Six treatments were used in the study: 90/10 Certified Angus Beef (CAB) ground sirloin, 90/10 ground beef, 80/20 CAB ground chuck, 80/20 ground chuck, 80/20 ground beef, and 73/27 CAB ground beef. Ground beef was processed into 151.2-g patties using a patty former with 2 consecutively formed patties assigned to blind consumer testing and the following 2 assigned to informed testing. Following cooking to 74°C, patties were cut into quarters and served to consumers. Consumers ( = 112) evaluated samples in 2 rounds for tenderness, juiciness, flavor liking, texture liking, and overall liking. Each trait was also rated as either acceptable or unacceptable. In the first round of testing, samples were blind evaluated, with no information about the treatments provided to consumers, but in the second round, product type and brand were disclosed prior to sample evaluation. Additionally, texture profile and shear force analyses were performed on patties from each treatment. Few differences were observed for palatability traits during blind consumer testing; however, during informed testing, 90/10 CAB ground sirloin was rated greatest ( < 0.05) for all palatability traits other than juiciness. Also, 90/10 CAB ground sirloin had increased ( < 0.05; (consumer informed score - consumer blind score)/consumer blind score) ratings for tenderness (17.4%), juiciness (36.5%), flavor liking (23.3%), texture liking (18.2%), and overall liking (24.7%) due to brand disclosure. Increased ( < 0.05) ratings were found for CAB products for multiple traits due to treatment disclosure, whereas the only non-CAB-branded product that received increased ( < 0.05) ratings during informed testing was 90/10 ground beef for tenderness and juiciness. Texture results indicated that decreased fat level increased hardness, cohesiveness, gumminess, and chewiness. These results indicate that when sampling ground beef without brand and product information, few consumers find differences in eating quality among ground beef treatments; however, when consumers are aware of the brand, fat level, and subprimal blend prior to sampling, these factors have a large impact on consumer eating satisfaction.

The effect of branding on consumer palatability ratings of beef strip loin steaks

The objective of this study was to determine the influence of knowing the brand or USDA grade on consumer palatability ratings of beef strip loin steaks. Strip loins were selected to represent 5 USDA grades and brands, USDA Select, Choice, Prime, Certified Angus Beef (CAB; upper 2/3 Choice), and Select, from carcasses of cattle classified as Angus on the basis of phenotype. After 21 d of aging, 2.5-cm-thick steaks were cut, consecutively cut steaks were paired for consumer evaluation. Consumer panelists ( = 112) evaluated samples for tenderness, juiciness, flavor liking, and overall liking. Additionally, consumers rated each palatability trait as either acceptable or unacceptable. Samples were fed in 2 rounds on the same day: blind and informed testing. In the first round, blind testing, consumers were served 1 sample from each treatment, with no product information provided. In the second round, consumers were informed of the brand or quality grade prior to sampling. During blind testing, CAB rated similar ( > 0.05) to Choice for all palatability traits; however, CAB rated greater ( < 0.05) than Choice for all traits during informed testing. Additionally, Angus Select and Select were rated similar > 0.05) for all traits when tested blind, but Angus Select was rated greater ( < 0.05) than Select for flavor and overall liking when brand was declared. When comparing blind and informed ratings, Angus Select and CAB had greater ( < 0.05) ratings for juiciness, flavor liking, and overall liking, and Prime had increased ( < 0.05) ratings for flavor liking and overall liking because of brand disclosure. However, ratings for Choice and Select samples were unaffected ( > 0.05) when brand was disclosed. Brand knowledge increased ( < 0.05) the percentage of Prime samples rated as acceptable for flavor and the percentage of Angus Select samples rated as acceptable for flavor and overall liking. Conversely, there was no difference ( > 0.05) in the percentage of Choice and Select samples rated as acceptable for all palatability traits. These data indicate that Prime, CAB, and Angus Select steaks receive an increase in consumer palatability perception, or "brand lift," which does not occur for Choice and Select beef.

Effects of sequential feeding of β-adrenergic agonists on cull cow performance, carcass characteristics, and mRNA relative abundance

The objectives of this study were to determine the effects of supplementation with a single β-adrenergic agonist (β-AA) or a sequence of β-AA on cow performance, carcass characteristics, and mRNA relative abundance of cull cows implanted and fed a concentrate diet. Sixty cull cows were implanted with Revalor-200 (200 mg of trenbolone acetate and 20 mg of estradiol) and assigned to 1 of 4 treatments (n = 15/treatment): CON = fed a concentrate diet only; RH = supplemented with ractopamine-HCl for the last 25 d before slaughter; ZH = supplemented with zilpaterol-HCl for 20 d before a 3-d withdrawal before slaughter; RH + ZH = supplemented with RH for 25 d, followed by ZH for 20 d before a 3-d withdrawal before slaughter. Ractopamine-HCl was supplemented at a dose of 200 mg·animal(-1)·d(-1), and ZH was supplemented at 8.33 mg/kg (100% DM basis) of feed. All cows were fed a concentrate diet for 74 d. Each treatment had 5 cows per pen and 3 replicate pens. Body weights were collected on d 1, 24, 51, and 72. Muscle biopsies from the LM were collected on d 24, 51, and at slaughter from a subsample of 3 cows per pen. Carcass traits were evaluated postslaughter. The 2 ZH treatments averaged 15.3 kg more BW gain, 0.20 kg greater ADG, and 7.8 cm(2) larger LM area than CON and RH treatments, and 21 kg more HCW than CON, but these differences were not significant (P > 0.10), likely due to a sample size of n = 15/treatment. The sequence of RH followed by ZH tended to optimize the combination of HCW, LM area, percent intramuscular fat, and lean color and maturity compared with the ZH treatment. Abundance of β(2)-adrenergic receptor (AR) mRNA was not altered in the RH + ZH treatment during RH supplementation from d 24 to 51 of feeding. However, the abundance of β(2)-AR mRNA increased (P < 0.05) the last 23 d of feeding for the RH treatment and tended (P = 0.10) to increase in ZH cows during ZH supplementation. For all cows, abundance of type IIa myosin heavy chain (MHC-IIa) mRNA decreased (P < 0.05) after 24 d of feeding. Abundance of MHC-IIx mRNA increased (P < 0.05) for ZH and RH + ZH treatments the last 23 d of feeding during ZH supplementation. Although few significant differences were observed in performance or carcass traits, mRNA quantification indicated that β-AA supplementation elicited a cellular response in cull cows. Implanting and feeding cull cows for 74 d, regardless of β-AA supplementation, added economic value by transitioning cows from a cull cow to what is referred to in industry as a white cow market in which cows have white fat resulting from grain feeding.

Influence of quality classification, aging period, blade tenderization, and endpoint cooking temperature on cooking characteristics and tenderness of beef gluteus medius steaks

Top sirloin butts (n = 162) were used to investigate the influence of quality classification, aging period, blade tenderization passes, and endpoint cooking temperature on the tenderness of gluteus medius steaks. Top sirloin butts (gluteus medius) from Select (SEL), Choice (CHO), and Certified Angus Beef (CAB) carcasses were obtained, aged for 7, 14, or 21 d, and either not tenderized or blade tenderized one or two times. Three steaks from each top sirloin butt were randomly selected and assigned to a final endpoint cooking temperature of 65.5, 71.0, or 76.6 degrees C. Cooking characteristics and Warner-Bratzler shear force (WBSF) were analyzed as a split-plot with a 3 x 3 x 3 factorial treatment structure of quality classification, aging period, and tenderization passes in the whole plot and endpoint cooking temperature in the subplot. Sensory panel data for CHO steaks cooked to 70 degrees C were analyzed with a 3 x 3 factorial treatment structure of aging period and tenderization passes. Thawing loss was greater (P < 0.05) for steaks aged 7 d than those aged 21 d. Cooking loss was greater (P < 0.05) for steaks aged for 14 and 21 d than those aged 7 d, and increased (P < 0.05) with each increasing endpoint temperature. Each increase in aging period resulted in lower (P < 0.05) WBSF values. In addition, steaks blade tenderized two times had lower (P < 0.05) WBSF values than steaks blade tenderized once or not at all. Within each quality classification, WBSF values increased (P < 0.05) as endpoint cooking temperature increased. When cooked to 71 or 76.6 degrees C, CHO and CAB steaks had lower (P < 0.05) WBSF than SEL steaks. Steaks blade tenderized one or two times received higher (P < 0.05) sensory panel ratings for myofibrillar and overall tenderness than steaks not blade tenderized. Connective tissue amount and overall tenderness ratings were higher (P < 0.05) for steaks aged 21 vs. 7 d. Postmortem aging and blade tenderization of gluteus medius steaks can improve tenderness, as measured by WBSF and sensory panel, without decreasing flavor or juiciness. When cooking to higher endpoint temperatures, higher quality classifications should be selected to minimize toughness due to cooking.

Beef quadriceps hot boning and modified-atmosphere packaging influence properties of injection-enhanced beef round muscles1,2

Two experiments were conducted to examine the effects of hot boning, modified atmosphere packaging, and injection enhancement on the oxidative and sensory properties of beef round muscles. The beef knuckle (quadriceps muscles) was partially hot boned within 1.5 h postmortem from one randomly selected side of each beef carcass (n = 14), whereas the quadriceps on the opposite side remained intact throughout a 48-h chilling period. At 5 d postmortem, biceps femoris, semimembranosus, vastus lateralis, and rectus femoris muscles from both hot- and cold-boned sides were injected with an enhancement solution consisting of water, salt, phosphate, and natural flavorings (rosemary) at either 6 (Exp. 1) or 10% (Exp. 2) of fresh muscle weight. Enhanced muscles were then processed into 2.54-cm-thick steaks, which were allotted randomly to high-oxygen (HiOx; 80% O2:20% CO2) or ultra-low oxygen (LoOx; 80% N2:20% CO2) modified atmosphere packaging. Regardless of hot boning or enhancement, steaks packaged in LoOx had lower thiobarbituric acid-reactive substances values (P < 0.05), more beef flavor intensity (P < 0.05), fewer off flavors (P < 0.05), and were more tender (P < 0.05) than steaks packaged in HiOx. Hot boning the knuckle had no effect on oxidative (P > or = 0.99) and sensory properties (P > or = 0.85). Increasing the level of injection enhancement from 6 to 10% introduced more rosemary and phosphate into the muscles, thereby decreasing the extent of oxidation, but also imparting a nontypical beef flavor. Packaging in LoOx atmosphere offered the optimal result of decreased oxidation and improved tenderness, without detriment to flavor. Injection enhancement (both 6 and 10%) created off-flavors attributable to the enhancement solution; however, the 10% injection seemed to offer more resistance to lipid oxidation.

Mechanical probes can predict tenderness of cooked beef longissimus using uncooked measurements1

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.

Effects of dietary additions of modified tall oil, chromium nicotinate, and L-carnitine on growth performance, carcass characteristics, and bacon characteristics of growing-finishing pigs

Eighty gilts were supplemented with modified tall oil (MTO), chromium nicotinate (CrNic), and L-carnitine to determine effects on growth and meat quality characteristics. Pigs were assigned to one of eight treatments in a 2 × 2 × 2 factorial with main effects of MTO (0 or 0.5%), CrNic (0 or 50 μg kg-1), and L-carnitine (0 or 50 mg kg-1). Pigs fed MTO had increased (P = 0.03) average daily gain and pigs fed CrNic had improved (P = 0.02) gain:feed. Bellies from pigs supplemented with MTO with no CrNic were firmer (P < 0.05) than bellies from all other treatment combinations. No differences (P > 0.05) were detected for longissimus muscle (LM) visual or objective color values. Furthermore, no differences (P > 0.05) were detected for LM Warner-Bratzler shear force or sensory traits. Bacon from pigs fed MTO had firmer (P < 0.05) slices than bacon from pigs fed no MTO.These data suggest improvements in growth performance from addition of 0.50% MTO and(or) 50 μg kg-1 CrNic to diets of finishing gilts. Supplementing with MTO, CrNic, and L-carnitine had minimal effects on carcass, LM color and sensory, or bacon characteristics. Key words: Pork, modified tall oil, chromium nicotinate, L-carnitine, longissimus muscle, bacon

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 increasing dietary niacin on growth performance and meat quality in finishing pigs reared in two different environments

We conducted two experiments to determine the effects of added dietary niacin on growth performance and meat quality in finishing pigs. Pigs were blocked by weight and assigned to one of six dietary treatments in both experiments. Dietary treatments consisted of a corn-soybean meal-based control diet (no added niacin) or the control diet with 13, 28, 55, 110, or 550 mg/kg of added niacin. In Exp. 1, pigs were housed at the Kansas State University research from with two pigs per pen (six pens per treatment per sex). In Exp. 2, pigs were housed with 26 pigs per pen (four pens per treatment per sex) in a commercial research barn. In Exp. 1, 144 pigs (initially 51.2 kg) were fed diets in two phases (d 0 to 25 and 25 to 62) that were formulated to 1.00 and 0.75% lysine, respectively. In Exp. 2, 1,248 pigs (initially 35.9 kg) were fed diets in four phases (d 0 to 28, 29 to 56, 57 to 84, and 85 to 117), with corresponding total lysine concentrations of 1.25, 1.10, 0.90, and 0.65% lysine, respectively. Added fat (6.0%) was included in the first three phases. In Exp. 1, average daily feed intake tended (quadratic, P < 0.07) to increase then return to values similar to control pigs as dietary niacin increased. Longissimus muscle (LM) 24-h pH (longissimus of pigs fed added niacin) tended to increase (control vs niacin, P < 0.06) for pigs fed added niacin. In the commercial facility (Exp. 2), increasing added niacin improved gain:feed (quadratic, P < 0.01) and subjective color score, and ultimate pH (linear, P < 0.01). Added niacin also decreased (linear, P < 0.04) carcass shrink, L* values, and drip loss percentage. Results from these two studies show that 13 to 55 mg/kg added dietary niacin can be fed to pigs in a commercial environment to improve gain:feed. It also appears that pork quality, as measured by drip loss, pH, and color, may be improved by higher concentrations of added dietary niacin.

Effects of modified tall oil and vitamin E on growth performance, carcass characteristics, and meat quality of growing-finishing pigs

Crossbred barrows (n = 72) were used to evaluate effects of diet supplementation with modified tall oil (MTO; 0.0 or 0.50%) and vitamin E (0, 22, or 110 IU/kg) on growth performance, carcass traits, and longissimus muscle (LM) quality traits of finishing pigs. Pigs were blocked by ancestry and initial BW and allotted randomly to treatments in a 2 x 3 factorial. Corn-soybean meal-based diets were fed in two phases: 45.5 to 81.6 (1.00% lysine) and 81.6 to 114.6 (0.75% lysine) kg BW with no added fat. From 45.5 to 81.6 kg, pigs fed MTO had greater ADG (P = 0.03) regardless of added vitamin E; otherwise, treatment did not affect growth performance. Carcasses from pigs fed MTO had reduced (P < 0.05) average backfat (2.76 vs 2.92 cm) and firmer bellies compared to those fed no MTO. Boneless loins were cut into 2.54-cm chops at 7 d postmortem and evaluated for display color, thiobarbituric acid-reactive substance (TBARS), Warner-Bratzler shear force (WBSF), and sensory panel ratings. Visual color was similar (P > 0.05) among treatments at 0 and 1 d of display. At 4 and 6 d of display chops from pigs fed MTO with 110 IU vitamin E/kg had less deterioration (P < 0.05) than chops from pigs fed MTO with 0 IU vitamin E/kg and 0.0% MTO with 22 or 110 IU vitamin E/kg. The CIE L*, a*, b* and spectral values also suggested a delay in color deterioration for chops from pigs fed MTO with 110 IU vitamin E/kg. At 6 and 8 d of display, chops from pigs fed 110 IU vitamin E/kg had lower (P < 0.05) L* values than those from pigs fed 0 or 22 IU vitamin E/kg, and higher (P < 0.05) a* values than those from pigs fed 0 IU vitamin E/kg feed. A higher (P < 0.05) %R630/%R580 (indicator of more oxymyoglobin) was observed for chops from pigs fed MTO with 110 IU vitamin E/kg than those from pigs fed 0.0% MTO with 22 or 110 IU vitamin E/kg and MTO with 0 IU vitamin E/kg. Chops from pigs fed MTO with 110 IU vitamin E/kg had lower (P < 0.05) TBARS values than those from pigs fed MTO with 0 IU vitamin E/kg. No differences (P > 0.05) were detected among treatments for WBSF or sensory evaluations. The addition of MTO in swine diets improved belly firmness and reduced backfat, and feeding MTO with high levels of vitamin E extended display life without affecting palatability of LM chops.

Effects of choice white grease or poultry fat on growth performance, carcass leanness, and meat quality characteristics of growing-finishing pigs

Eighty-four crossbred gilts were used to evaluate the effects of dietary choice white grease (CWG) or poultry fat (PF) on growth performance, carcass characteristics, and quality characteristics of longissimus muscle (LM), belly, and bacon of growing-finishing pigs. Pigs (initially 60 kg) were fed a control diet with no added fat or diets containing 2, 4, or 6% CWG or PF. Diets were fed from 60 to 110 kg and contained 2.26 g lysine/Mcal ME. Data were analyzed as a 2 x 3 factorial plus a control with main effects of fat source (CWG and PF) and fat level (2, 4, and 6%). Pigs fed the control diet, 2% fat, and 4% fat had greater (P < 0.05) ADFI than pigs fed 6% fat. Pigs fed 6% fat had greater (P < 0.05) gain/feed (G/F) than pigs fed the control diet or other fat levels. Subcutaneous fat over the longissimus muscle from pigs fed CWG had more (P < 0.05) moisture than that from pigs fed PF. Feeding dietary fat (regardless of source or level) reduced (P < 0.05) the amount of saturated fats present in the LM. Similarly, 4 or 6% fat decreased (P < 0.05) the amount of saturated fats and increased unsaturated fats present in the bacon. No differences (P > 0.05) were observed for ADG, dressing percentage, leaf fat weight, LM pH, backfat depth, LM area, percentage lean, LM visual evaluation, LM waterholding capacity, Warner-Bratzler shear and sensory evaluation of the LM and bacon, fat color and firmness measurements, or bacon processing characteristics. Adding dietary fat improved G/F and altered the fatty acid profiles of the LM and bacon, but differences in growth rate, carcass characteristics, and quality and sensory characteristics of the LM and bacon were minimal. Dietary additions of up to 6% CWG or PF can be made with little effect on quality of pork LM, belly, or bacon.

Effects of feeding modified tall oil and supplemental potassium and magnesium on growth performance, carcass characteristics, and meat quality of growing-finishing pigs

Eighty crossbred gilts (initially 45.9 kg) were allotted randomly to one of four dietary treatments by weight and ancestry. The trial was arranged as a 2 × 2 factorial with two levels of modified tall oil (MTO) (0 or 0.50%) and added K2SO4-2MgSO4 (0 or 2%), equating to daily K and Mg intakes of 10.84 and 7.75 g, respectively. The corn-soybean meal diets were fed in two phases [45.9 to 76.2 and 76.2 to 118.1 kg body weight (BW)], and supplemental K/Mg was added in place of corn for the final 7 d preslaughter (starting at 114.1 kg BW). Dietary treatment did not affect (P > 0.10) average daily gain (ADG), average daily feed intake (ADFI), or gain to feed ratio (G/F). Feeding MTO decreased average backfat (P = 0.05) and increased intramuscular marbling (P = 0.04). Modified tall oil increased (P = 0.02) percentage lean, and K/Mg supplementation lowered (P = 0.04) longissimus muscle glycogen content. Dietary treatment did not affect (P > 0.10) other carcass characteristics or measures of meat quality. Feeding MTO increased plasma glucose (P = 0.05) and decreased (P = 0.10) base excess in the extracellular fluid. Feeding K/Mg decreased (P < 0.10) plasma pH, BUN, and base excess in the whole-blood and extracellular fluid and increased (P < 0.10) ionized Mg++ and lactate. These results support earlier research identifying MTO as a carcass modifier and contributor to meat composition and quality. Potassium and Mg supplementation altered whole-blood profiles and longissimus muscle glycogen content in a manner expected to improve pork quality, although not observed. Key words: Swine, modified tall oil, potassium, magnesium, meat quality

Effects of modified tall oil versus a commercial source of conjugated linoleic acid and increasing levels of modified tall oil on growth performance and carcass characteristics of growing-finishing pigs

Two experiments were conducted to evaluate the effects of conjugated linoleic acid (CLA)-enriched feed additives for swine. These additives included a source of CLA that was commercially available (CLA-60) and modified tall oil (MTO). Experiment 1 used 36 barrows (initially 37.6+/-2.8 kg) to compare the effects of CLA-60 and MTO on growth performance and carcass characteristics of finishing pigs. The corn-soybean meal diets contained .50% soybean oil (control), .50% CLA-60, or .50% MTO. Pigs fed CLA-60 had less (P = .03) ADG from 37.6 to 72.6 kg than the control pigs; otherwise, pigs fed either CLA-60 or MTO had growth performance similar (P > .15) to that of the control pigs. Pigs fed MTO grew faster (P = .03) and consumed more feed (P = .10) over the duration of the experiment (37.6 to 106.4 kg) than pigs fed CLA-60. Dietary treatment did not affect (P > .15) plasma triglycerides or carcass characteristics, but pigs fed either MTO or CLA-60 had greater saturation of fatty acids in the adipose tissue at the 10th rib than pigs fed the control diet. Experiment 2 used 80 barrows (initially 33.4+/-2.2 kg) to examine the effects of increasing levels of MTO on growth performance and carcass characteristics of finishing pigs. The corn-soybean meal diet contained 1% cornstarch, which was replaced with MTO to give dietary levels of .25, .50, or 1.00% MTO. Dietary treatment did not affect (P > .15) growth performance. Feeding increasing levels of MTO quadratically decreased (P = .02) average backfat thickness and longissimus muscle drip loss (P = .04) and quadratically increased longissimus muscle area (P = .07) and percentage lean (P = .03). Feeding MTO tended to increase belly firmness (P < .10) compared with pigs fed the control diet. These traits appeared to be optimized with .50% MTO. In summary, pigs fed MTO had greater ADG, ADFI, and ending BW than pigs fed CLA-60. Feeding MTO does not appear to affect growth performance but improves carcass lean content and may additionally improve some aspects of meat quality in growing-finishing pigs.

Effects of modified tall oil and creatine monohydrate on growth performance, carcass characteristics, and meat quality of growing-finishing pigs

The effects of feeding modified tall oil (MTO) and creatine monohydrate (CMH) on growing-finishing pig growth performance, carcass characteristics, and meat quality were determined. Eighty cross-bred barrows (initially 45.4 kg) were allotted randomly to one of four dietary treatments by weight and ancestry. The experiment was arranged as a 2 x 2 factorial with two levels of MTO (0 or 0.50%), which were fed throughout the growing-finishing period, and two levels of CMH (0 or 25 g/d), which were fed for the final 10 d before slaughter. The corn-soybean meal diets were fed in two phases (45.4 to 78.9 kg and 78.9 to 117.5 kg BW). When CMH was added to the diet in place of corn, average BW was 107.5 kg. Feeding MTO increased (P < 0.05) ADG and gain:feed ratio (G/F) during the 45.4- to 78.9-kg growth interval and tended to improve (P = 0.10) G/F during the 45.4- to 107.5-kg growth interval. Dietary treatment did not affect (P > 0.15) growth performance during the 78.9- to 107.5-kg growth interval. Modified tall oil increased (P = 0.02) G/F during the 10-d CMH supplementation period, and CMH numerically (P = 0.11) increased ADG and G/F. Supplementation of CMH did not affect (P > 0.20) any measured carcass characteristic or measures of meat quality at 24 h or 14 d postmortem. Feeding MTO reduced average back-fat (P = 0.05) and 10th rib backfat (P = 0.01) but did not affect (P > 0.10) other measured carcass characteristics or measures of meat quality at 24 h postmortem. Modified tall oil increased (P = 0.02) L* values (lightness) and tended to increase (P < 0.10) thawing and cooking losses of longissimus muscle chops at 14 d postmortem. These data demonstrate that MTO improves growth performance and reduces backfat in growing-finishing pigs, but supplementation of CMH, under the conditions of this experiment, was not beneficial for growing-finishing pigs.

Interrelationships among evaluations of beef longissimus and semitendinosus muscle tenderness by Warner-Bratzler shear force, a descriptive-texture profile sensory panel, and a descriptive attribute sensory panel

The objective of our study was to examine the interrelationships among Warner-Bratzler shear force (WBSF) determinations, evaluation by a highly trained descriptive-texture-profile (DTP) sensory panel, and evaluation by a trained descriptive attribute (DA) sensory panel as affected by muscle fiber orientation of samples and shear-blade type. Longissimus lumborum and semitendinosus muscles (n = 18 of each) were cut into 2.54-cm steaks, which were cooked to 71 degrees C. Cores were obtained with two methods (parallel to the muscle fiber orientation and perpendicular to the cut steak surface), used for WBSF determinations with the typical V-shaped blade and modified WBSF determinations with a flat blade, and presented to the DTP and DA sensory panels. The V-shaped blade resulted in 1.4 to 2.5 kg lower (P < .05) mean WBSF values than the flat blade for both muscles. Cores taken parallel to the longissimus muscle fiber orientation had .64 kg higher (P < .05) mean WBSF values than cores taken perpendicular to the cut steak surface. Both panels detected differences among carcass replications; however, a panelist x replication effect (P < .05) occurred for the DA panel. Both panels detected differences (P < .05) in muscle fiber orientation for attributes related to tenderness. Correlations between sensory panel scores and WBSF values were dependent on blade type and coring method. Blade type and coring method had greater effects on correlations between sensory scores and WBSF values for the DTP panel than for the DA panel. Correlations between scores by both sensory panels and WBSF values were comparable. The more highly trained DTP panelists were more consistent in their evaluations of texture attributes; however, they were more sensitive to muscle fiber orientation. Both panels were effective in detecting differences among carcass replications.

Effect of source of cattle and distance transported to a commercial slaughter facility on carcass bruises in mature beef cows

OBJECTIVE

To determine the effect of source of cattle and distance cattle were transported to a commercial slaughter facility on prevalence and severity of carcass bruises in mature beef cows.

DESIGN

Epidemiologic investigation.

SAMPLE POPULATION

Carcasses from 3,955 beef cows from 11 states assembled in 89 procurement lots.

PROCEDURE

Each carcass was scored for bruise severity and location. Source of cattle was categorized. Distance from source to slaughter facility was determined. An ANCOVA was used to determine effects of variables on carcass bruises.

RESULTS

Mature beef cows marketed through livestock auctions conducting first-point testing for brucellosis, especially when transported longer distances (> 325 km) to slaughter facilities, had a greater number and severity of carcass bruises than cows originating from ranches or livestock auctions not conducting first-point testing. There was an increase in number of rib bruises in cows originating from livestock auctions not conducting first-point testing. Prevalence and severity of bruises were not significantly affected by transportation distance between cows originating from auctions not conducting first-point testing and cows originating from ranches.

CLINICAL IMPLICATIONS

A strong association existed between handling for brucellosis testing prior to sale for slaughter and distance transported to slaughter facility with carcass bruises in mature beef cows. Bruises are major quality defects that decrease carcass value and slaughter-cow prices. Repeated handling and restraint as well as long-distance transport are issues to consider regarding the responsibility of the livestock industry to provide for the safety and well-being of cattle sold for slaughter.

Factors affecting the occurrence of dark-cutting beef and selected carcass traits in finished beef cattle

A data set was used to determine how various factors affect the occurrence of dark-cutting beef and selected carcass traits in finished beef cattle. Data were collected in 1989 and 1990 from one packer with plants located in Amarillo, TX; Boise, ID; Dakota City, NE; and Garden City, KS. The data set consisted of 3,659 lots consisting of 724,639 cattle. Compared with those at Boise and Dakota City, cattle slaughtered in Amarillo and Garden City had a higher incidence of dark cutters (1.1 vs .3%; P < .01) and a lower quality grade (50 vs 64% Choice plus Prime; P < .01). The highest incidences of dark cutters occurred during August, September, and October (1.1 to 1.4%; P < .01), with incidences of .4 to .7% during the other months. Carcass quality grade was higher during January, February, and March compared with May through November (60 to 62% Choice plus Prime vs 52 to 58%; P < .01). As the number of cattle in a lot increased, the incidence of dark cutters increased from .4 to 1.2% (P < .01), and quality grade declined from 62 to 52% Choice plus Prime (P < .01). As the mean weight of cattle in the lot increased, the incidence of dark cutters declined from .94 to .6% (P < .01), and carcasses grading Choice plus Prime increased from 56 to 62% (P < .01). With cattle held over a weekend or holiday, ("carry cattle") the incidence of dark cutters increased from .8 to 1.6% (P < .01). We conclude that packing plant location, month of the year, weight of cattle, carry cattle, and number of cattle in a lot are most likely to influence the incidence of dark cutters and carcass quality traits.

Effects of ultrasound and convection cooking to different end point temperatures on cooking characteristics, shear force and sensory properties, composition, and microscopic morphology of beef longissimus and pectoralis muscles

Longissimus and pectoralis muscles were removed from 10 steer carcasses at 4 d postmortem, aged for 14 d at 2 degrees C, then assigned to either ultrasound or convection cooking to either 62 degrees C or 70 degrees C internal end point temperature. During cooking, time-temperature profiles and energy consumption were monitored. Ultrasound cooking resulted in greater (P < .05) cooking speed, greater (P < .05) moisture retention and less (P < .05) cooking loss, greater (P < .05) efficiency of energy consumption, a more uniform cooking environment, and less (P < .05) instrumental peak-force work to shear muscle samples than convection cooking. The ultrasound treatment also resulted in a reduction (P < .05) in soluble collagen content and superior (P < .05) myofibrillar tenderness, as determined by a trained sensory panel, than convection cooking. Electron micrographs indicated that ultrasound-cooked muscles had longer sarcomeres, larger diameter fibers, and more myofibrillar disruption and shattering. Longissimus muscles cooked faster (P < .05) and more (P < .05) energetically efficient, had less (P < .05) total collagen, and were superior (P < .05) in instrumental evaluated texture and sensory tenderness than pectoralis muscles. Cooking to 70 degrees C caused greater (P < .05) moisture and cooking losses, required more (P < .05) time and energy input to cook, and negatively (P < .05) affected instrumental textural and sensory tenderness characteristics. Electron micrographs indicated a shortening of sarcomeres, more deterioration of the banding structure, reduction in fiber diameter, and breakdown of endomysial and perimysial connective tissue at an internal temperature of 70 degrees C vs 62 degrees C. This research identifies ultrasound cooking as a new, rapid, energy-efficient method that may improve some meat textural attributes.

Effects of blast chilling and postmortem calcium chloride injection on tenderness of pork longissimus muscle

Two studies were conducted to evaluate the effects of blast chilling of carcasses and injection with calcium chloride (CaCl2) at 24 h postmortem on Warner-Bratzler shear values (WBS) and moisture losses of pork longissimus muscles (LM). In a preliminary study, Exp. 1 was conducted to determine whether the injection procedure using 100% water had an influence on WBS of pork LM. Injecting pork LM with water at 24 h postmortem had no effect on WBS (P = .64). In Exp. 2, 27 carcass sides were assigned to 1) blast chilling for 1 h at 25 degrees C and then chilling for 23 h at 1 degree C or 2) standard chilling for 24 h at 1 degree C. At 24 h postmortem, the LM was removed from each side and divided into anterior (AL) and posterior (PL) halves. For each LM, the CaCl2 treatment was assigned randomly to either the AL or PL. Those receiving CaCl2 were injected with a .3 M solution at 10% by weight. Muscles then were stored for 3 d at 1 degree C before 2.54-cm chops were removed, cooked to an internal temperature of 70 degrees C, and allowed to cool for 2 h, then six 1.27-cm cores were taken and sheared. No differences (P > .05) in purge or cooking loss were observed, but rapid chilling reduced (P < .05) the combination of purge and cooking loss without influencing WBS (P = .77). The injection of CaCl2 at 24 h postmortem lowered (P < .05) WBS of pork LM muscle. Therefore, the tenderness of pork can be enhanced by injection of CaCl2.

Influence of steroid implants and concentrate feeding on performance and carcass composition of cull beef cows

Sixty nonpregnant, mature beef cows were used to evaluate the influence of steroid implants on performance and carcass composition of beef cows fed a high-concentrate diet. Twelve nonfed cows were slaughtered at 0 d. Remaining cows were stratified by weight and randomly assigned to an implant treatment and feeding period (28 or 56 d). Treatments included 1) no implant (control), 2) a 200-mg trenbolone acetate (TBA) implant, 3) a 200-mg testosterone propionate +20 mg of estradiol benzoate (TEB) implant, or 4) both implants (TBA + TEB). As days on feed increased, hot carcass weight (HCW), carcass soft tissue (CST) weight, adjusted fat thickness (AFT), longissimus muscle area (LMA), percentage of CST, and percentage of CST lipid increased (P < .05) and percentage of CST crude protein and moisture decreased (P < .05). Cows fed for 56 d accumulated (P < .05) more kilograms of lean than cows fed for 28 d, and cows fed for 28 d tended (P = .08) to have more kilograms of lean than nonfed cows. Cows fed for 56 d had (P < .05) higher dressing percentages than nonfed cows or cows fed for 28 d, and nonfed cows had (P < .05) higher dressing percentages than cows fed for 28 d. Implanted cows compared with control cows had (P < .05) heavier final weights, increased gains, improved feed efficiency, heavier hot carcass weights, larger LMA, higher cutability yield grades, compositionally leaner CST (higher percentage of moisture and protein and lower percentage of lipid), and more kilograms of lean. In addition, double-implanted (TBA + TEB) cows had (P < .05) more kilograms of CST than control and TBA-implanted cows. Furthermore, cows implanted with TBA had (P < .05) lower dressing percentages than TEB-implanted cows, less AFT than controls, and fewer kilograms of lipid than cows on the other three treatments. Full feeding of thin beef cows for 28 or 56 d increased carcass weight through an increase in CST lean as well as fat (lipid). The live performance and accretion of lean during realimentation can be enhanced by using anabolic implants.

Influence of steroid implants and concentrate feeding on carcass and longissimus muscle sensory and collagen characteristics of cull beef cows

Sixty nonpregnant, mature beef cows were used to determine the effects of steroid implants and concentrate feeding on carcass quality, longissimus muscle (LM) collagen characteristics, and LM sensory traits. Twelve nonfed cows were slaughtered at 0 d to establish basal carcass values. The remaining 48 cows were assigned randomly in a 2 x 4 factorial arrangement to an implant treatment and fed for either 28 or 56 d. The implant treatments were 1) nonimplanted (controls), 2) a 200-mg trenbolone acetate (TBA) implant, 3) a 200-mg testosterone propionate +20 mg estradiol benzoate (TEB) implant, or 4) both implants (TBA+TEB). Carcasses from cows fed for 28 and 56 d had improved (P < .05) LM marbling, lean maturity, and quality grade; a lighter (P < .05) LM color (higher Hunter L* values); a higher (P < .05) percentage of LM soluble (heat-labile) collagen; and a lower (P < .05) LM Warner-Bratzler shear force value (more tender) than carcasses from nonfed cows. Feeding for 28 and 56 d also improved (P < .05) LM sensory panel traits of flavor intensity, connective tissue amount, myofibrillar tenderness, and overall tenderness. Feeding cows for an additional 28 d (to 56 d) improved (P < .05) LM visual lean color, texture, and firmness and carcass fat color. All LM HunterLab color measurements were higher (P < .05) for cows fed for 56 d compared to 28 d, indicating a brighter, redder, more vivid color. Implant treatments did not influence (P > .05) carcass quality or LM color. Steaks from implanted cows compared to controls had (P < .05) more soluble (heat-labile) collagen, a higher percentage of soluble collagen, and improved sensory traits of tenderness (myofibrillar and overall) and connective tissue amount. Steaks from TBA-implanted cows compared to the other implant treatments had superior (P < .05) LM sensory evaluations for myofibrillar and overall tenderness. Feeding thin cows a high-concentrate diet for 28 d improved quality grade and LM sensory traits, and feeding for 56 d improved LM lean and carcass fat color. Implanting fed cows improved LM sensory panel tenderness.

The influence of genotype, sex, and dietary lysine on pork subprimal cut yields and carcass quality of pigs fed to either 104 or 127 kilograms

One hundred twenty pigs (initially 44 kg BW) were used to determine the effects of genotype, sex, and dietary lysine on subprimal cut yields and carcass quality. Within genotype (high or medium potential for lean tissue gain), barrows and gilts were fed separately either a .90 or .70% lysine diet until the mean weight of each pen of three pigs reached 104 kg. Then one pig was removed and dietary lysine for the remaining two pigs was decreased to .75 or .55%, respectively. At both 104 and 127 kg BW, carcasses from high-lean genotype (HLG) pigs and gilts had (P < .01) higher percentages of boneless closely trimmed ham, loin, and shoulder than carcasses from medium-lean genotype (MLG) pigs and barrows, respectively. At 104 kg BW HunterLab values indicated (P < .01) that HLG longissimus muscle (LM) was redder, more yellow, and more intense in color than MLG LM. The LM from HLG gilts had (P < .05) higher Warner-Bratzler shear values (less tender) than LM from HLG barrows and MLG pigs at 104 kg BW. At 127 kg BW, HLG LM was visually firmer (P < .05) and more reddish-pink (P < .01); had HunterLab values (P < .01) that indicated a darker, redder color; had less moisture exudate (P < .05), thaw loss (P < .01), and percentage of lipid (P < .01); and had a higher pH (P < .05) than MLG LM. Barrow LM had more marbling (P < .05), a higher percentage of lipid (P < .01), less moisture exudate (P < .05), and less thaw loss (P < .01) than LM from gilts. The LM from HLG barrows had higher (P < .05) Warner-Bratzler shear values than the LM from HLG gilts and MLG pigs at 127 kg BW. Overall, the dietary regimens used in this trial resulted in minimal differences in either carcass quality or cutability. The production option of feeding HLG gilts to 127 kg can be used to optimize carcass cutability and quality traits.

The effect of dietary lysine on growth, carcass composition, and lipid metabolism in high-lean growth gilts fed from 72 to 136 kilograms

One hundred fourteen high-lean growth gilts (72.5 kg BW) were used to determine the apparent digestible lysine requirement for maximum growth performance and carcass protein deposition rate from 72.5 to 136 kg BW. The experiment was a randomized complete block design with initial BW used to establish blocks. Six dietary treatments were included, ranging from .44 to .94% (.10% increments) apparent digestible lysine (.62 to 1.13% total lysine) with six replicate pens per treatment and three pigs per pen. Pig weights and feed consumption were collected weekly to determine ADG, ADFI, and gain: feed ratio (G/F). Six gilts were slaughtered at 72.5 kg BW to determine initial carcass composition. When the mean weight of pigs in a pen reached 104 or 136 kg, one pig per pen was selected (closest to 104 or 136 kg, respectively) and slaughtered for determination of carcass measurements and composition. From 72.5 to 104 kg and from 104 to 136 kg, ADG and G/F increased (linear, P < .05; quadratic, P < .10, respectively) as apparent digestible lysine increased. From 72.5 to 136 kg, G/F increased (quadratic, P < .10) as apparent digestible lysine increased. Average backfat thickness and longissimus muscle area at 104 kg were not influenced (P > .10) by apparent digestible lysine. However, average backfat thickness increased (quadratic, P < .05) with increasing digestible lysine for gilts slaughtered at 136 kg. Carcass CP accretion was not influenced (P > .10) from 72.5 to 104 kg but tended to increase (linear, P < .10) from 72.5 to 136 kg as digestible lysine increased. Plasma and longissimus muscle cholesterol concentrations were unaffected (P > .10) by increasing digestible lysine. These results suggest that high-lean growth gilts require greater dietary lysine than current NRC (1988) estimates to maximize ADG, G/F, and carcass CP accretion from 72.5 to 104 and from 104 to 136 kg.

Effects of restraint and isolation stress and epidural blockade on endocrine and blood metabolite status, muscle glycogen metabolism, and incidence of dark-cutting longissimus muscle of sheep

Crossbred lambs (47.3 kg BW) were used to study the effects of restraint and isolation stress on endocrine status and blood metabolites, antemortem glycogenolysis, and incidence of the dark-cutting condition (DCC) in the longissimus muscle (LM) and to determine the role of muscle contraction in the formation of the DCC in sheep. Lambs were assigned randomly to three treatments: unstressed controls (C); a single 6-h period of restraint and isolation stress (RIS); and a single 6-h period of RIS following epidural blockade (RISEB) with lidocaine. Blood was collected immediately before lambs were subjected to RIS and RISEB and at 12-min intervals during the 6-h period. Serum concentrations of glucose, lactate, and insulin were higher (P < .01) in RIS and RISEB lambs than in C lambs. Serum free fatty acid concentrations were higher (P < .01) in stressed lambs only during the first 4 h of stress. Plasma epinephrine and cortisol concentrations also were higher (P < .01) in RIS and RISEB lambs than in C lambs. Lambs were slaughtered within 30 min after completion of stress. Immediately after stunning and at .75, 3, 6, 12, and 24 h postmortem, samples were removed from the LM in the hindsaddle and foresaddle for glycogen, lactate, and pH determinations. Muscle pH was elevated (P < .01) by RIS and RISEB; ultimate pH exceeded 6.0. The LM from carcasses of RIS and RISEB lambs had lower (P < .01) glycogen and lactate concentrations in both regions than the LM of C lambs. Subjecting sheep to a single 6-h period of RIS was an effective animal model to induce the DCC. Failure of the epidural blockade to inhibit antemortem glycogen metabolism and formation of the DCC indicates that muscle contraction was not requisite to those processes in sheep.

Influence of dietary lysine on growth and carcass composition of high-lean-growth gilts fed from 34 to 72 kilograms

One hundred eight high-lean-growth gilts (34.4 kg BW) were used to determine the dietary lysine requirement to maximize growth, carcass characteristics, and protein accretion from 34 to 72.5 kg BW. The experiment was a randomized complete block design; initial BW served as the blocking factor. Six dietary treatments were included, ranging from .54 to 1.04% (.10% increments) digestible lysine (.69 to 1.25% total lysine). Pigs were housed in pens of three, with six replicate pens per treatment. Pig weights and feed consumption were collected weekly to calculate ADG, ADFI, and gain:feed (G/F). Initially, five pigs were slaughtered to determine baseline carcass composition. When the mean weight for pigs in a pen reached 55 and 72.5 kg, one pig per pen was randomly selected and slaughtered for carcass measurements. The right side of each carcass was ground twice and sampled to determine carcass composition and tissue accretion rates. Average daily gain was increased by dietary lysine from 34 to 55 kg (linear, P < .01), from 55 to 72.5 kg (linear, P < .10), and from 34 to 72.5 kg (linear, P < .01). Although ADFI from 34 to 55 and from 55 to 72.5 kg was not influenced by dietary lysine, ADFI for the entire experiment tended to decrease (quadratic, P < .10) as digestible lysine increased. Increased dietary lysine resulted in improved G/F from 34 to 55 kg (linear, P < .01) and from 55 to 72.5 and 34 to 72.5 kg (quadratic, P < .01). Average backfat thickness was not influenced by dietary lysine at 55 kg but decreased (linear, P < .05) as dietary lysine increased at 72.5 kg. At 55 kg, longissimus muscle area was larger (linear, P < .05) for gilts fed increased digestible lysine. However, longissimus muscle area was similar for all treatments at 72.5 kg. Gilts fed increased digestible lysine had greater CP accretion from 34 to 55 kg (linear, P < .01), 55 to 72.5 kg (linear, P < .05; quadratic, P < .10), and from 34 to 72.5 kg (quadratic, P < .05). Based on the feed intake observed in this study, the high-lean-growth gilt requires at least 22 g/d total lysine intake from 34 to 72.5 kg to maximize CP accretion.

Effects of the interrelationship between genotype, sex, and dietary lysine on growth performance and carcass composition in finishing pigs fed to either 104 or 127 kilograms

One hundred twenty pigs (initially 44 kg BW) were used to determine effects of the interrelationship between genotype, sex, and dietary lysine on growth performance and carcass composition in a 2 x 2 x 2 factorial arrangement. Genetic comparisons were made between pigs characterized with either a high or medium potential for lean tissue gain. Within genotype, barrows and gilts were separately fed either a .90 or .70% lysine diet until the mean weight of pigs in each pen of three reached 104 kg. One pig per pen was slaughtered to determine carcass characteristics and chemical composition. From 104 to 127 kg, dietary lysine was lowered to .75 or .55% for pigs fed .90 or .70% dietary lysine, respectively. When the pigs' mean weight met or exceeded 127 kg, both pigs were slaughtered to determine carcass characteristics and chemical composition. Carcass length, longissimus muscle area, average backfat thickness, and 10th rib fat depth were measured 24 h postmortem on the chilled carcasses. The right side of each carcass was then ground and chemically analyzed to determine protein and lipid accretion rates. No interactions were detected from 44 to 104 kg; therefore, main effect means will be discussed. At 104 kg, high-lean pigs had increased ADG (P < .01) and gain:feed ratio (G/F; P < .05) compared with medium-lean pigs. Barrows had increased (P < .05) ADG and ADFI but exhibited a poorer (P < .01) G/F than gilts. Pigs fed .90% lysine had improved (P < .01) ADG compared with pigs fed .70% lysine.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcass traits and the occurrence of dark cutters in pregnant and nonpregnant feedlot heifers

The objective of this study was to determine whether the occurrence of dark cutters and selected carcass traits differ between pregnant and nonpregnant feedlot heifers. Feedlot heifers (n = 8,292) were identified at slaughter as being either nonpregnant, pregnant with a moderate-sized fetus (midgestation), or pregnant with a large fetus (late gestation). This was based on visual appraisal of a gravid uterus at the evisceration table. After chilling (24 to 72 h), carcass data were collected. Cattle originated from 23 different commercial feedyards located within a 350-km radius of a commercial slaughter facility located in southwest Kansas. Across slaughter lots, the incidence of pregnancy varied from 0 to 25% with an overall mean of 4.74%. Carcass traits of heifers with moderate or large fetuses did not differ (P > .15). Compared with carcasses from nonpregnant heifers, carcasses from pregnant heifers were 4.5 kg lighter (P < .01), had .11 cm more fat thickness (P < .01), and exceeded the number of carcasses that graded Choice or Prime by 6% (P < .01). Carcasses from pregnant heifers had higher maturity scores (P < .01) and there was no incidence of dark cutters (P < .01) compared with a 1.7% incidence of dark cutters in carcasses from nonpregnant heifers. Any economical advantage in the pregnant heifers due to their higher percentage of Choice carcasses and lower incidence of dark cutters may be offset by their increased carcass fat thickness and lower dressing percentage.

Influence of repeated restraint and isolation stress and electrolyte administration on pituitary-adrenal secretions, electrolytes, and other blood constituents of sheep

Crossbred lambs (n = 24) were blocked by weight and assigned within blocks to four treatments applied in two replications of a 2 x 2 factorial arrangement. Main effects included no stress (NS) or three consecutive days of restraint and isolation stress (RIS) and treatment with either water (W) or an electrolyte (E) solution. Each lamb in the RIS treatment group was moved from its home stanchion to another room, isolated from visual and tactile contact with other lambs, and restrained for 6 h on three consecutive days. Lambs received either distilled W or E (320 mL) on each of the 3 d of stressor treatment. On the morning of the 3rd d of stressor treatment, blood samples were collected at 1-h intervals for 6 h for determination of concentrations of ACTH, cortisol, and lactate. Also, blood was collected at the conclusion of, and 18 h after, the termination of stressor treatment (at slaughter) to measure serum electrolyte concentrations and other blood constituents. Polynomial curves fit to plasma concentrations of ACTH, cortisol, and lactate data differed (P < .005) between RIS and NS lambs during the last 6-h stressor bout. Stressed lambs had lower (P < .05) serum calcium and alkaline phosphatase concentrations than did NS lambs. Serum glutamic oxaloacetic transaminase was increased (P < .05) 20- to 30-fold in RIS lambs. Restraint and isolation stress caused clear increases in plasma concentrations of ACTH, cortisol, lactate, and glutamic oxaloacetic transaminase but had minimal effects on serum electrolytes. Electrolyte treatment had no appreciable effect on pituitary-adrenal secretions or any other measured component of blood.

Validation of real-time ultrasound technology for predicting fat thicknesses, longissimus muscle areas, and composition of Brangus bulls from 4 months to 2 years of age

Sixty Brangus bulls were evaluated live using two real-time ultrasound instruments and four technicians to estimate longissimus muscle area (LMA) and 12th rib fat thickness (FT) every 4 mo beginning at 4 and 12 mo of age, respectively, and continuing until 24 mo of age. Ten bulls were slaughtered every 4 mo to determine actual LMA and FT, 9-10-11th rib chemical composition, yield grade (YG) factors, and empty body weight (EBW). Live animal traits were used to predict 9-10-11th rib composition, YG, and EBW. Scanned mean FT was accurate (P less than .05) at 16 mo and was not different (P = .09) from the actual mean FT (95% of the time the error in estimation was less than or equal to .33 cm). Scanned mean LMA was accurate (P less than .05) at 12 mo (95% of the time the error in estimation was less than or equal to 20.0 cm2). Absolute differences between scanned and actual mean FT and LMA were different (P less than .05) from zero for the main effects of month, operator and(or) interpreter, and instrument. Increased level of operator skill did not improve the accuracy of FT or LMA measurements, whereas increased level of skill of the interpreter of scans did improve the accuracy of LMA estimations. There was no difference (P greater than .05) between ultrasound instruments in accuracy of estimating FT or LMA. The most accurate prediction of YG occurred at 12 mo and incorporated LW, hip height (HH), and ultrasound LMA (R2 = .95, SD = .14). The most accurate prediction of EBW occurred at 16 mo and incorporated LW, HH, and ultrasound FT (R2 = .99, SD = 6.65 kg), whereas the most accurate equation for combined slaughter periods incorporated LW, HH, and ultrasound LMA (R2 = .99, SD = 20.71 kg). We conclude that scanning of LMA at 12 mo and of FT at 12 or 16 mo were sufficiently accurate to characterize groups of bulls; however, some individual measurements were quite inaccurate. Measurements at other months should not be considered accurate for either individuals or groups of bulls. Yield grade and EBW can be accurately estimated from live animal and ultrasound measurements, which may be useful in identifying Brangus cattle with superior cutability and may eliminate the need for serial slaughter in research projects.

Effects of implanting ram and wether lambs with zeranol at birth and weaning on palatability and muscle collagen characteristics

Thirty-five zeranol-implanted (I) and nonimplanted (NI) ram and wether lambs representing four treatments (implanted rams [IR], nonimplanted rams [NIR], implanted wethers [IW], and nonimplanted wethers [NIW]) were evaluated for meat palatability and muscle collagen characteristics. Rib (longissimus muscle, LM) chops from I lambs were juicier (P less than .05) than rib chops from NI lambs. Chops from IR lambs had more (P less than .05) detectable connective tissue and lower myofibrillar and overall tenderness scores than chops from NIR, IW, or NIW lambs. Warner-Bratzler shear (WBS) values tended to be higher (P = .06) for LM chops from rams than for those from wethers, but WBS values for Biceps femoris (BF) chops were similar (P greater than .05) for rams and wethers. Implanting did not affect (P greater than .05) WBS values. Rams had more (P less than .05) LM heat-labile (soluble, SC), nonheat-labile (insoluble, IC), and total collagen (TC) and a higher (P less than .05) percentage of SC (SC/TC) than did wethers. Soluble collagen, TC, and percentage of SC for the BF were higher (P less than .05) and IC tended (P = .09) to be higher in chops from rams than in those from wethers. Implanting did not affect (P greater than .05) collagen amount or solubility. Serum nonprotein hydroxyproline (NPHP) was higher (P less than .05) in rams than in wethers throughout the feeding period and tended (P = .05) to be higher at slaughter. Implanting did not affect (P greater than .05) serum NPHP.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of zeranol implants in ram and wether lambs on performance traits, carcass characteristics, and subprimal cut yields and distribution

In two separate 2 x 2 factorial arrangements, 69 male, crossbred lambs were allotted randomly to the following treatments: 1) nonimplanted (NI) rams, 2) implanted (I) rams, 3) NI wethers, and 4) I wethers. In Trial 1, 36 lambs were allotted to treatment groups at birth (n = 9) and I lambs were implanted with 12 mg of zeranol between 1 and 3 d of age and again at weaning (average age of 62 d). Lambs were slaughtered at three time-constant end points of 78, 93, and 107 d on feed postweaning (average age of 155 d). Rams grew faster postweaning, were more efficient in their feed conversion, were heavier at slaughter, and had lower numerical yield grades than did wethers (P less than .05). Implanted lambs tended (P = .08) to grow faster and were (P less than .05) more efficient in their feed conversion than NI lambs. Rams produced heavier (P less than .05) trimmed subprimal shoulders, loins, and legs and had (P less than .05) a higher percentage of their carcass weight in the subprimal shoulder than did wethers. During Trial 2, NI rams (n = 8), I rams (n = 8), NI wethers (n = 8), and I wethers (n = 9) were allotted to treatment groups, and I lambs were implanted at average ages of 14, 55, and 98 d. After weaning, lambs were weighed every 14 d and were slaughtered 7 d after reaching a minimum weight of 50 kg (average age of 148 d).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of zeranol-implantation periods on palatability of longissimus steaks from young bulls and steers

Fifty-five fall-born, Simmental-crossbred, male calves were allotted at birth to one of five treatments: bulls castrated at 5 mo and implanted from birth to slaughter (ST); bulls implanted from birth to slaughter (BI-BS); bulls implanted from birth to weaning (BI-BW); bulls implanted from weaning to slaughter (BI-WS) and non-implanted control bulls (CB). Implanted calves received 36 mg of zeranol at approximately 100-d intervals. Calves were fed a high-concentrate diet from 8.1 mo of age to an average slaughter age of 17 mo. Longissimus steaks (LS) were evaluated for palatability traits by both a trained sensory panel (TSP) and a take-home consumer panel (CP). Conclusions from both panels were similar. The TSP found LS from ST to be juicier (P less than .05) than LS from all bull groups, and to be more tender (P less than .05) than LS from BI-BW and BI-WS. The CP found LS from ST to be juicier, more tender and more acceptable (P less than .05) than LS from BI-BW, BI-WS and CB. Steaks from BI-BS were more tender (P less than .05) than LS from BI-WS and CB. Steaks from BI-BS and BI-BW had lower (P less than .05) shear values than LS from CB, but LS from ST had lower (P less than .05) shear values than LS from all bull groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Implanting young bulls with zeranol from birth to four slaughter ages: III. Growth performance and endocrine aspects

Seventy-two Simmental bull calves were assigned randomly either to a zeranol implanted (I) or nonimplanted (NI) control group. Within 3 d after birth, bulls assigned to the I treatment were implanted with 36 mg zeranol and reimplanted every 84 d until slaughter. Calves were weaned at 7.2 mo, preconditioned for 2 wk, and assigned within treatment to slaughter ages 12.0, 13.8, 15.7 and 17.4 mo. Blood samples were taken bimonthly from 8.3 to 16.6 mo of age. Weight gains, feed:gain ratios and slaughter and carcass weights were similar (P greater than .10) for I and NI bulls for the total feeding period. Weight gains for NI bulls were larger (P less than .05) from 7.7 to 9.5 mo and from 11.3 to 12.2 mo of age, whereas gains for I bulls were greater from 12.2 to 14.1 mo. Serum estradiol-17 beta (E2) and testosterone (T) concentrations were higher (P less than .05) for NI bulls at 8.3, 9.2, 10.2, 11.1, 12.1 and 13.0 mo. However, at 13.9 and 14.8 mo, E2 concentrations were higher (P less than .10) for I bulls. A similar, but nonsignificant (P greater than .10), trend was noted for T concentrations of I bulls at 13.9 and 14.8 mo. Rapid increases in E2 concentrations were observed from 8.3 to 9.2 mo in NI bulls, but from 12.1 to 13.9 mo in I bulls. Similarly, T concentrations increased rapidly from 8.3 to 10.2 mo in NI bulls, but from 12.1 to 14.8 mo in I bulls. Peak concentrations of T and E2 for NI bulls were observed near 11 and 13 mo, respectively, whereas peak T and E2 levels were delayed in I bulls until near 14 mo. Periods of greater weight gains for both NI and I bulls corresponded to rapidly increasing E2 and T concentrations. Serum thyroxine concentrations were lower (P less than .05) for I bulls at 13.9 mo but similar to NI bulls at all other ages. Serum insulin concentrations were higher (P less than .05) for I bulls than for NI bulls at 8.3, 10.2, 11.1 and 12.1 mo. Regardless of treatment, insulin concentrations increased with increasing age. Carcasses from I bulls were fatter (P less than .05) and tended (P = .09) to have smaller ribeye areas/100 kg carcass. Fat thicknesses for both treatments increased (P less than .05) from 13.8 to 15.7 mo. Skeletal maturity scores, 9-10-11th rib bone percentages and femur measurements indicated an increased skeletal maturation in I bulls.(ABSTRACT TRUNCATED AT 400 WORDS)

Proportion of types I and III collagen in longissimus collagen from bulls and steers

The proportion of types I and III intramuscular collagen in longissimus muscles of Simmental bulls (n = 8) and steers (n = 8) 17 mo of age was studied. Longissimus samples taken 7 d after slaughter were evaluated for total collagen, types I and III collagen, heat-soluble collagen, sensory panel traits and Warner-Bratzler shear force. Intramuscular collagen (IMC) was isolated and digested with cyanogen bromide, and peptides were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Percentage of type III IMC was calculated from the total of types I and III collagen as determined from the peak area of densitometric scans of the cyanogen bromide peptides alpha 1(I)CB8 and alpha 1(III)CB8. Longissimus muscles from steers had lower (P less than .05) Warner-Bratzler shear values, less (P less than .05) sensory panel-detectable connective tissue and more (P less than .05) tender panel ratings for muscle fiber tenderness and overall tenderness. Muscles from steers had more (P less than .05) heat-soluble collagen than those from bulls, but no differences (P greater than .05) were found for total collagen and percentage of type III collagen. Some intramuscular-collagen characteristics may have contributed to the less tender muscle of bulls. However, the proportion of types I and III collagen did not account entirely for the tenderness difference between steer and bull muscles. Because there were differences in collagen solubility in muscles from steers and bulls, other collagen characteristics such as crosslinking or fiber size may have been more important than collagen type.

Implanting young bulls with zeranol from birth to four slaughter ages: I. Live measurements, behavior, masculinity and carcass characteristics

Seventy-two Simmental bull calves were allotted randomly at birth to either a zeranol (Ralgro) implanted (I) treatment or a nonimplanted control (C) group. At birth, bulls assigned to the I treatment were implanted with 36 mg of zeranol and reimplanted at average intervals of 84 d until slaughter. Calves were weaned at 7.2 mo, preconditioned for 2 wk, and randomly assigned by treatment to slaughter ages of 12.0, 13.8, 15.7 and 17.4 mo and fed an 83% concentrate diet until slaughter. At 7.7 mo and all slaughter ages, live weights and hip heights were similar (P greater than .10), but I bulls had lower (P less than .05) masculinity scores than C bulls. Scrotal circumferences for I bulls were smaller (P less than .05) at 7.7, 12.0, 13.8 and 15.7 mo, but similar (P greater than .10) at 17.4 mo to C bulls. Behavioral observations of passive bunting, mounting attempts, facility rubbing and overall activity were less (P less than .05) for I bulls than C bulls from 12.0 to 13.8 mo but similar (P greater than .10) from 13.8 to 17.4 mo. Aggressive bunting was less (P less than .05) for I bulls during five of the seven observation times for the 12.0-to-13.8-mo period only. Slaughter and carcass weights and dressing percentages were similar (P greater than .10) for I and C bulls. Skeletal maturity and marbling scores, fat thicknesses, yield grades and 9-10-11th rib fat percentages were higher (P less than .05) and lean maturities, forehead hide weights, high dermis thicknesses, femur measurements and 9-10-11th rib bone weights and percentages were lower (P less than .05) for I than C bulls. Rib eye areas and carcass masculinity traits of jump muscle and crest of I bulls were less (P less than .05) at 13.8 mo but reached similar (P greater than .10) development to C bulls at 15.7 mo. Testicle weights of I bulls were lighter (P less than .05) at 12.0, 13.8 and 15.7 mo, but similar (P greater than .10) to C bulls at 17.4 mo. Growth traits (all weights plus hide and femur measurements) and maturation traits (skeletal and lean maturities, marbling scores, fat thicknesses and pizzle eye sizes) increased the most from 12.0 to 13.8 mo and 13.8 to 15.7 mo, respectively. We concluded that implanting young bulls with zeranol from birth to slaughter had minimal effects on live measurements, improved carcass desirability and delayed masculinity and behavioral development.