Flank Streaking Research Articles

84 Carcass Characteristics, Meat Color and Fatty Acid Profile of Feedlot Lambs Fed Novel Anthocyanin-rich Corn Cobs

Abstract Hi-A™ is a unique type of corn developed by Texas A&M AgriLife that has high anthocyanin. A completely randomized design trial was used to evaluate the effects of three roughages, Hi-A™ corn cobs, low-A (regular) corn cobs and bermudagrass hay (BGH), in feedlot Rambouillet ewe lamb (n = 10/treatment) diets on carcass characteristics, meat color and fatty acids (FA) profile. Lambs were fed experimental diets (20% roughage and 80% concentrate) for 63-d. Then, lambs were harvested, and the carcasses evaluated. Boneless lamb loin chops, 2.5 cm thick, were fabricated and analyzed for color and FA. Data were analyzed by ANOVA for a completely randomized design with diet as fixed effects and animal as a random effect with an alpha of 0.05. Carcass weight, loin eye area (LEA), body wall thickness, fat thickness, leg score, marbling, skeletal maturity, lean maturity, and flank streaking did not differ among treatments (P > 0.05). Dressing percentage was greater (P < 0.05) in the lambs fed BGH compared to Hi-A™ diets; neither of which differed (P > 0.05) from lambs fed Low-A. Instrumental color characteristics L* (darkness to lightness), a* (redness), b* (yellowness) and chroma (total color) of fresh lamb loin chops measured under retail display did not vary (P > 0.05) among treatments. Hue Angle (discoloration) was greater (P < 0.05) in loin chops from lambs fed Hi-A™ than Low-A diets, while BGH did not differ (P > 0.05) from the other treatments. Retail display day influenced (P < 0.05) all the instrumental color characteristics, with the highest values of L*, a*, b*, and chroma on day 1 and Hue Angle on days 3 and 4. No differences (P > 0.05) were observed in the meat FA profile. No advantages of using Hi-A™ corn cobs in feedlot lamb diets were observed regarding carcass characteristics, meat color and FA profile.

PSVI-23 Depot- specific patterns of mRNA and miRNA gene expression in adipose tissue from Texel-cross and Suffolk lambs

Abstract Excess fat deposition is costly to the producer in terms of input and final product; it also usually does not occur equally across all adipose depots. Further examination is necessary to determine a correlation between varying gene expression and fatty acid composition in different tissue depots, and further, across different breeds. Texel-Suffolk (n = 5) and Suffolk-Suffolk (n = 4) lambs were finished to 203 d of age and used to compare both mRNA and microRNA (miR) gene expression changes between breed and among tissue depots. Seven different depots were harvested and snap-frozen from all nine lambs. The liver, longissimus muscle of the rib, kidney fat, mesenteric fat, omental fat, subcutaneous fat, and intermuscular fat were all harvested. Texel-sired lambs had greater (P < 0.05) flank streaking, quality grade, and weight of fat depots compared to Suffolk. Texel-cross lambs had higher (P < 0.05) oleic-to-stearic fatty acid ratio than Suffolk lambs in this study, displaying a breed difference concerning this desaturation ratio. Tissue and breed interactions were observed for oleic-to-stearic and palmitoleic-to-palmitic ratio differences (P < 0.05) depending on tissue type. Tissue and breed interactions were trending in various tissues concerning the expression of the gene, stearoyl-CoA desaturase-1(SCD-1). SCD-1 seemed to be upregulated (P < 0.10) in a multitude of tissues while others do not appear to be differentially expressed, dependent upon breed. Data showed an association between SCD-1 and mi-199a-3p among different tissue variations. This may suggest that adipose tissue is more complex than what is currently known. Lipogenic gene expression differed between tissue and adipose depots, and could potentially broaden targets that could aid in maximizing animal efficiency.

Selection on a small genomic region underpins differentiation in multiple color traits between two warbler species.

Speciation is one of the most important processes in biology, yet the study of the genomic changes underlying this process is in its infancy. North American warbler species Setophaga townsendi and Setophaga occidentalis hybridize in a stable hybrid zone, following a period of geographic separation. Genomic differentiation accumulated during geographic isolation can be homogenized by introgression at secondary contact, whereas genetic regions that cause low hybrid fitness can be shielded from such introgression. Here, we examined the genomic underpinning of speciation by investigating (1) the genetic basis of divergent pigmentation traits between species, (2) variation in differentiation across the genome, and (3) the evidence for selection maintaining differentiation in the pigmentation genes. Using tens of thousands of single nucleotide polymorphisms (SNPs) genotyped in hundreds of individuals within and near the hybrid zone, genome‐wide association mapping revealed a single SNP associated with cheek, crown, breast coloration, and flank streaking, reflecting pleiotropy (one gene affecting multiple traits) or close physical linkage of different genes affecting different traits. This SNP is within an intron of the RALY gene, hence we refer to it as the RALY SNP. We then examined between‐species genomic differentiation, using both genotyping‐by‐sequencing and whole genome sequencing. We found that the RALY SNP is within one of the highest peaks of differentiation, which contains three genes known to influence pigmentation: ASIP, EIF2S2, and RALY (the ASIP‐RALY gene block). Heterozygotes at this gene block are likely of reduced fitness, as the geographic cline of the RALY SNP has been narrow over two decades. Together, these results reflect at least one barrier to gene flow within this narrow (∼200 kb) genomic region that modulates plumage difference between species. Despite extensive gene flow between species across the genome, this study provides evidence that selection on a phenotype‐associated genomic region maintains a stable species boundary.

Effects of Marbling and Postmortem Aging on Consumer Assessment of United States Lamb Loin

Consumer sensory analysis was performed to evaluate the effects of three marbling categories [LOW, Intermediate (MED), and HIGH] and 2 postmortem aging categories (21 d and 42 d) on the palatability of lamb loin chops as determined by U.S. consumers and to determine the relationship between marbling, flank streaking, intramuscular fat percentage (IMF), and palatability traits. Marbling and aging did not interact to affect any of the scores for palatability attributes, their acceptances, or the frequency of their overall eating quality classifications (P < 0.05). Consumers rated HIGH treatments (P < 0.05) as more tender, juicier, and with greater flavor liking and overall liking than MED or LOW, which were similar for all traits (P > 0.05). Aging also influenced (P < 0.05) all traits, as consumers scored 21 d samples greater for all palatability traits than their 42 d counterparts. A greater (P < 0.05) percentage of consumers categorized 42 d samples as ‘unsatisfactory’ and fewer as ‘better than everyday’ or ‘premium quality’ than 21 d samples. A larger proportion of consumers categorized HIGH samples as ‘premium quality’ than MED or LOW and fewer called HIGH ‘good everyday quality’ compared to MED (P < 0.05). Flank streaking, marbling score, and IMF were all influenced (P < 0.01) by marbling category in a linear fashion. Increasing marbling score, more so than flank streaking, was positively linked to increasing eating quality scores. Also, tenderness, juiciness and flavor liking are major drivers for consumer sensory scores for overall liking, with flavor liking having the strongest relationship to overall liking of lamb. Overall, consumers preferred HIGH marbling over LOW and MED marbling loin chops, but had difficulty distinguishing between LOW and MED. Furthermore, extending postmortem aging of lamb loin from 21 to 42 d reduced scores for eating quality traits.

Evaluation of Lamb Carcass Quality Characteristics in Relation to Consumer Sensory Scores

ObjectivesFlank streakings and confirmation drive lamb quality grading, but in beef, quality is based on marbling in the ribeye. However, little to no research has been conducted linking flank streaking to lamb eating quality. The objective of this study was to determine the relationship between carcass fat indicator traits, intramuscular fat percentage (IMF), and the palatability traits of tenderness (TEN), juiciness (JUIC), flavor liking (FLAV) and overall liking (OALL), as rated by U.S. consumersMaterials and MethodsCarcasses (n = 180; 60/treatment) were selected at a commercial lamb processor in Greeley, CO based on pork marbling standards (PMS) as low (PMS 1), intermediate (PMS 2) or high (PMS 3+), with marbling score and flank streaking (FS) being determined within seconds of carcass ribbing. Full lamb loins (IMPS 232; 1 × 1in) representing the 3 targeted marbling levels [LOW, Medium (MED,) HIGH] were obtained, vacuum packaged, shipped to Texas Tech University, and stored under refrigeration (2 to 4°C) until fabrication. On d 21 postmortem, loins were removed from packaging, and marbling (MB) was assessed following a 10-min bloom period. Loins were fabricated, leaving only the Longissimus dorsi, then manually sliced into 2.5 cm thick chops, vacuum packaged, and either frozen immediately or stored at 2°C until 42 d postmortem, then frozen. Untrained consumers (n = 360) from Lubbock, TX; Hicksville, OH; Clemson, SC; Logan, UT; and Stillwater, OK rated TEN, JUIC, FLAV and OALL on 100-mm line scales. Data for fat measures (FS, 21d MB, and IMF) were analyzed as complete randomized design using the GLIMMIX procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC) with fixed effects of target marbling level. Treatment LS means were separated with the PDIFF option of SAS (ɑ = 0.05). Pearson correlation coefficients were determined using the CORR procedure of SAS.ResultsFS, MB, and IMF were all influenced (P < 0.01) by target marbling level in a linear fashion. As expected, HIGH had the highest values (FS:Mt54, MB: Md09, and 6.2% IMF), MED were intermediate (FS:Sm71, MB: Sm56, and 4.4% IMF), and LOW had the lowest values (FS:Sl53, MB: Sl41, and 3.7% IMF). With flank streaking being commonly used to evaluate lamb quality, a strong positive correlation would be expected with marbling level and IMF. Within the eating quality traits, FLAV was most strongly correlated (r = 0.93; P < 0.01) to OALL, followed by JUIC (r = 0.63) and tenderness (r = 0.62). TEN and JUIC scores were also strongly related (r = 0.75; P < 0.01) to each other. There were strong relationships (P < 0.01) between MB and IMF (r = 0.70), as well as between FS with MB and IMF (r = 0.60, 0.44, respectively). When examining the relationships between FS with the palatability traits, only JUIC had a correlation (r = 0.07; P < 0.01) with FS. MB was correlated (P < 0.01) with TEN, JUIC, FLAV, and OALL, (r = 0.09, 0.13, 0.09, and 0.09, respectively). However, IMF was only related (P < 0.01) to TEN (r = 0.08) and JUIC(r = 0.09).ConclusionIncreasing MB, more so than FS, was positively linked to increasing eating quality scores. Fortunately, FS and MB were strongly associated; however, neither FS nor MB had strong linear correlations with lamb eating quality. Also, tenderness, juiciness and flavor liking are major drivers for consumer sensory scores for overall liking, with flavor liking having the biggest impact on overall liking of lamb.

Effects of Marbling and Postmortem Aging on Consumer Assessment of United States Lamb Loin

Consumer sensory analysis was performed to evaluate the effects of three marbling categories [LOW, Intermediate (MED), and HIGH] and 2 postmortem aging categories (21 d and 42 d) on the palatability of lamb loin chops as determined by U.S. consumers and to determine the relationship between marbling, flank streaking, intramuscular fat percentage (IMF), and palatability traits. Marbling and aging did not interact to affect any of the scores for palatability attributes, their acceptances, or the frequency of their overall eating quality classifications (P 0.05). Aging also influenced (P < 0.05) all traits, as consumers scored 21 d samples greater for all palatability traits than their 42 d counterparts. A greater (P < 0.05) percentage of consumers categorized 42 d samples as ‘unsatisfactory’ and fewer as ‘better than everyday’ or ‘premium quality’ than 21 d samples. A larger proportion of consumers categorized HIGH samples as ‘premium quality’ than MED or LOW and fewer called HIGH ‘good everyday quality’ compared to MED (P < 0.05). Flank streaking, marbling score, and IMF were all influenced (P < 0.01) by marbling category in a linear fashion. Increasing marbling score, more so than flank streaking, was positively linked to increasing eating quality scores. Also, tenderness, juiciness and flavor liking are major drivers for consumer sensory scores for overall liking, with flavor liking having the strongest relationship to overall liking of lamb. Overall, consumers preferred HIGH marbling over LOW and MED marbling loin chops, but had difficulty distinguishing between LOW and MED. Furthermore, extending postmortem aging of lamb loin from 21 to 42 d reduced scores for eating quality traits.

Effects of added protein and dietary fat on lamb performance and carcass characteristics when fed differing levels of dried distiller's grains with solubles

The objectives of this study were to evaluate the influence of dietary protein and fat in dried distiller's grains with solubles (DDGS) on feedlot performance and carcass characteristics finishing lambs. Sixty crossbred lambs (29.16±4.59kg) were allotted into pairs (ewe and wether; 6 pairs/trt) and fed one of five isocaloric dietary treatments: (1) a corn based diet with DDGS included to meet CP requirements (∼25% of DM; CON), (2) CON with DDGS included at twice the amount of CON (∼50% of DM; 50DDGS), (3) CON with added corn protein in the form of gluten meal to be similar of CP in the 50DDGS diet (CON+CP), (4) CON with added vegetable oil to be similar to the crude fat in the 50DDGS diet (CON+VO), and (5) CON with corn protein and vegetable oil added to be similar to the CP and crude fat in the 50DDGS diet (CON+CPVO). Wether lambs were harvested when they obtained a common 12th rib fat depth endpoint of 0.5cm. Ewe lambs were returned to the flock. Data were analyzed using the MIXED procedure of SAS. Contrasts between (1) CON vs. elevated CP diets (50DDGS, CON+CP, and CON+CPVO; PRO), (2) CON vs. elevated fat diets (50DDGS, CON+VO, and CON+CPVO; FAT) and (3) CON vs. diets with both elevated CP and fat (50DDGS and CON+CPVO; PF) were analyzed. Final BW, days on feed, and G:F did not differ as a result of dietary treatment (P≥0.29). However, DMI was decreased (P=0.03) in the lambs fed PRO diets compared with CON fed lambs. Average daily gain tended (P=0.08) to decrease in the lambs fed the PRO diets compared with the lambs fed CON. Lambs did not differ (P>0.05) in HCW, dressing percentage, 12th rib fat depth, LM area, body wall thickness, yield grade, flank streaking, leg score, percent boneless, closely trimmed retail cuts, and LM ether extract. Therefore, these data indicate that DDGS can be included in feedlot lamb diets at levels up to 50% of DM without negatively affecting feedlot performance, carcass quality, and metabolite concentrations.

Effect of thiamine concentration on animal health, feedlot performance, carcass characteristics, and ruminal hydrogen sulfide concentrations in lambs fed diets based on 60% distillers dried grains plus solubles1

Limited data are available regarding the influence of thiamine supplementation on the incidence of polioencephalomalacia (PEM) in lambs fed diets containing increased concentrations of S in the diet (>0.7%). Therefore, our objective was to evaluate the influence of thiamine supplementation on feedlot performance, carcass quality, ruminal hydrogen sulfide gas concentrations, and incidence of PEM in lambs fed a finishing diet containing 60% distillers dried grains with solubles (DDGS; DM basis). Two studies were conducted using completely randomized designs to evaluate the influence of concentration of thiamine supplementation. Study 1 used 240 lambs fed in 16 pens, whereas study 2 used 55 individually fed lambs. Lamb finishing diets contained 60% DDGS, which resulted in a dietary S concentration of 0.73% (DM basis). Treatments diets were based on the amount of supplemental thiamine provided: 1) no supplemental thiamine (CON), 2) 50 mg/animal per day (LO), 3) 100 mg/animal per day (MED), or 4) 150 mg/animal per day (HI). Additionally, in study 2, a fifth treatment was included, which contained 0.87% S (DM basis; increased S provided by addition of dilute sulfuric acid) and provided 150 mg of thiamine/animal per day (HI+S). In study 1, ADG decreased quadratically (P = 0.04), with lambs fed the CON, LO, and MED diets gaining BW at a greater rate than lambs fed the HI diet. In study 1, DMI responded quadratically (P < 0.01), whereas G:F tended to differ linearly (P = 0.08) to concentration of thiamine supplementation, with MED lambs having greater DMI and decreased G:F. No differences (P > or = 0.17) in lamb performance were observed in study 2. In both studies, most carcass characteristics were unaffected, with the exception of a tendency for decreased carcass conformation (study 1; P = 0.09) and greater flank streaking (study 2; P = 0.03). No differences in ruminal hydrogen sulfide concentration (P > 0.05) among treatments were apparent until d 10, at which point lambs fed the LO diet had less hydrogen sulfide concentrations than all other treatments. Lambs fed HI had the greatest concentrations of hydrogen sulfide on d 31 (1.07 g of hydrogen sulfide /m(3); P < 0.009). Ruminal pH did not differ (P = 0.13) and averaged 5.6 +/- 0.06. No clinical cases of PEM were observed during the course of either study. The use of thiamine as a dietary additive to aid in the prevention of PEM in finishing lambs does not appear to be necessary under the conditions of this study.

Effects of crude glycerin on performance and carcass characteristics of finishing wether lambs1

The objective of this study was to evaluate the effects of crude glycerin on performance and carcass characteristics in finishing wether lambs. Thirty black-faced, Suffolk-cross wether lambs (44.1 +/- 5.6 kg initial BW) were stratified and blocked by BW to 1 of 5 individually fed, isocaloric, isonitrogenous dietary treatments containing 0, 5, 10, 15, or 20% crude glycerin (88% pure) on a DM basis. Diets were fed once daily for ad libitum consumption and contained 15% chopped hay, approximately 25% dried distillers grains with solubles, and the specified treatment combination of cracked corn replaced with increasing amounts of crude glycerin. Wethers were weighed on 14-d intervals and were selected for slaughter when they reached an approximate 12th-rib fat depth of 0.51 cm (28 to 84 d on trial). Carcass characteristics were collected after a 48-h chill. Dry matter intake (linear, P = 0.004) and ADG (quadratic, P = 0.05) increased with increasing concentrations of glycerin in the diet during the first 14 d of the feeding period. Similarly, G:F tended to increase quadratically (P = 0.06) with increasing concentrations of crude glycerin in the diet during the first 14 d. However, there were no differences among treatments for final BW, days on feed, or cumulative DMI, cumulative ADG, and cumulative G:F (P >or= 0.11). Body wall thickness, dressing percent, HCW, LM area, flank streaking, leg score, conformation score, quality grade, yield grade, and percent boneless, closely trimmed retail cuts did not differ (P >or= 0.21). Adding up to 15% crude glycerin to finishing wether diets improved feedlot performance, particularly during the first 14 d, without any concomitant effect on carcass characteristics.

Effect of breed-type on performance and carcass traits of intensively managed hair sheep

The objectives of this study were to evaluate growth performance and carcass characteristics of intensively managed purebred and crossbred hair sheep, and determine the value of the Dorper breed as a terminal sire on St.Croix and St. Croix-cross dams. Animals used were Dorper×St. Croix (DS), and Dorper×Romanov×St. Croix (DX), Katahdin (KA), St. Croix (SC), and 3/4 St. Croix- 1 4 Romanov (SX) wether lambs. From birth to weaning, daily gains (ADG) were greater ( P<0.01) for DS and KA lambs than SC and SX lambs; yet, from weaning to harvest, ADG was greatest ( P<0.01) for DS, followed by DX, SC, SX, and KA lambs. Carcass weights were heavier ( P<0.01) for DS than all other breeds and DS, DX, KA, and SX carcasses had greater ( P<0.01) fat thickness measurements than SC carcasses. The longissimus thoracic (LT) area was largest ( P<0.01) for DS and DX carcasses and smallest ( P<0.01) for SC and SX carcasses. Skeletal, lean, and overall maturities were similar ( P>0.10) among the breed types; however, carcasses from SC lambs received lower ( P<0.02) flank streaking scores than DS, KA, and SX lambs. Conformation scores and quality grades were greater ( P<0.01) for DS and DX than SC or SX carcasses. Although L* values of the LT were similar ( P>0.10), the LT from DX lambs was redder ( P<0.01) and more yellow ( P<0.01) than that of DS and SC lambs. The shear force values of the LT chops from KA lambs were greater ( P<0.01) than all other breed types. Results indicate that improvements in live animal performance, carcass muscularity, and quality can be achieved by using Dorper sires on purebred and crossbred St. Croix dams.

A New Hybrid Warbler (Dendroica Nigrescens × D. Occidentalis) and Diagnosis of Similar D. Townsendi × D. Occidentalis Recombinants

Abstract We use 13 color characters to describe the first known Dendroica nigrescens × D. occidentalis hybrid. Because this specimen was collected in the southeastern Cascade Mountains of Washington during the breeding season, D. townsendi, D. occidentalis, and D. nigrescens are the only plausible parents for a hybrid male falling within the black-throated clade of Dendroica warblers. Multiple character states in the hybrid refute the alternative parental combinations, townsendi × occidentalis and townsendi × nigrescens. Two characteristics of this hybrid suggested further tests of the parentage of 38 problematic hybrids that were treated previously as townsendi × occidentalis recombinants by assumption only. These hybrids lack yellow on their breast, the only character that refutes a nigrescens × occidentalis parentage. The new hybrid is intermediate between nigrescens and occidentalis in the color of its posterior face and its anterior crown; thus, we scored these new characters in the 38 problematic hybrids. None of these 38 specimens was intermediate or white in either of these regions, and there was no correlation between having tinges of white in these regions and the extent of flank streaking. These results fail to support nigrescens in the parentage of these 38 specimens; furthermore, none of the problematic hybrids carried a nigrescens mitochondrial DNA haplotype. Thus, we conclude that all are unusual recombinants of townsendi × occidentalis hybridization, rather than nigrescens × occidentalis hybrids.

Comparison of different magnesium sources on lamb muscle quality

Wether lambs ( n=20) were used to compare the effect of dietary magnesium oxide (MgO), unweathered Magnesium Mica® (UMM) and weathered Magnesium Mica® (WMM) on muscle quality. Lambs were fed a corn-based, control diet (Ctrl), or the Ctrl supplemented with either MgO, UMM, or WMM for 95 days before harvest. Following a 24-h chill, carcasses were fabricated, and L*, a* and b* values were determined on the triceps brachii (TB), longissimus thoracis (LT), semimembranosus (SM), and semitendinosus (ST) muscles. Supplemental magnesium had no ( P > 0.10) effect on live and carcass weights, fat thickness, loin eye area, and USDA yield grade. Carcasses from lambs supplemented with MgO had higher ( P < 0.10) flank streaking scores and USDA quality grades than those from lambs fed diets containing UMM. Although magnesium-supplementation had no ( P > 0.10) effect on marbling scores, the LT from Ctrl-fed lambs had more ( P < 0.05) intramuscular lipid than lambs fed diets containing UMM or WMM. Lambs supplemented with UMM had greater ( P < 0.05) LT shear force values than lambs fed MgO or WMM. Magnesium-supplementation had no ( P > 0.10) effect on muscle color; however, supplementing finishing diets with UMM may result in less palatable lamb.

Gonadal function, sexual behavior, feedlot performance, and carcass traits of ram lambs actively immunized against GnRH.

The effect of active immunization against GnRH on production, carcass, and behavioral traits was examined in ram lambs fed to a uniform slaughter weight. Lambs (initial BW = 32.6+/-1 kg) were stratified by BW and assigned at random to one of four treatment groups (n = 12 lambs/group). Lambs were untreated, castrated, or actively immunized against GnRH using a GnRH-keyhole limpet hemocyanin conjugate (1 mg) emulsified with either Freund's complete adjuvant (FCA) or another oil-based adjuvant (ISA). Animals were housed individually and slaughtered at 58 kg BW. Immunoneutralization of GnRH reduced (P < .05) testes weight and the concentration of testosterone in serum at slaughter. Suppression of testicular size and function was most clearly evident in animals immunized using FCA. Final anti-GnRH titer was also highest in lambs immunized using FCA. Several measures of sexual behavior (frequency of mounts and ejaculations) were also reduced (P < .05) in animals immunized using FCA. The duration of the feeding period was greater (P < .05) for castrated lambs than for untreated lambs, and intermediate feeding periods were required for FCA and ISA lambs. Average daily gain was greater (P < .05) in untreated than in castrated, FCA, or ISA lambs. Similarly, feed efficiency for untreated lambs was greater (P < .05) than for castrated, FCA, or ISA lambs, but feed efficiency did not differ among castrated, FCA, or ISA lambs. Longissimus muscle area, lean and bone maturity, overall quality, muscling score, flank streaking, and color of fat did not differ among treatments. Intact, FCA, and ISA lambs had more (P < .05) desirable yield grades, less (P < .05) backfat, and less (P < .05) marbling than castrated lambs. In summary, immunization against GnRH decreased testicular weight and reduced (P < .05) feedlot performance and sexual behavior to levels comparable to those of castrated males. Partitioning of nutrients for growth and deposition of fat, however, seems to differ among immunologically castrated and physically castrated lambs. This difference in nutrient partitioning may be due to residual testicular activity in immunized lambs.

Effect of plane of nutrition and age on carcass maturity of sheep.

One hundred twenty ewe and wether lambs were fed high (76% TDN, 12.3% crude protein) or low (70.6% TDN, 16.1% crude protein) energy diets and slaughtered at average ages of 261, 356 or 469 d. High planes of nutrition for lambs at 356 or 469 d of age resulted in heavier carcasses, thicker fat depth and higher flank streaking scores compared to lambs fed low planes of nutrition. Rib bone, break joint and overall maturity scores were not influenced (P greater than .05) by diet. Metacarpal and metatarsal bones from lambs fed high planes of nutrition were slightly longer and heavier and required more force to break (P less than .05) compared with bones from lambs fed low planes of nutrition. The majority of the ewes fed high or low planes of nutrition had fused growth plates and possessed spool joints by 469 d; none of the wethers had spool joints. An additional 27 wethers were slaughtered at an average of 480, 578 or 662 d. Rib bone, break joint and overall maturity scores were not different (P greater than .05) for animals fed the high or low energy diets, but bone weight and shaft break force values were higher for those fed high energy diets. At 662 d of age, only 20% of the wethers on each dietary regimen possessed fused growth plates. Overall, plane of nutrition in market-weight lambs and yearlings had very little influence on the presence or absence of a break joint or on other bone maturity scores.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcass grades, rack composition and tenderness of sheep and goats as influenced by market class and breed

Compared to Spanish and Angora goats, sheep had heavier ( P < 0.05) carcass weights, more youthful USDA overall maturity scores, higher flank streaking scores, higher USDA leg conformation scores, larger longissimus muscle areas, and produced loin chops with lower shear force values. Rambouillet sheep had ( P < 0.05) higher scores for USDA skeletal and overall maturity, more feathering and flank streaking, higher USDA leg conformation scores and produced loin chops with lower shear force values than Barbados and Karakul sheep. Karakul sheep (especially the young intact males) had higher adjusted fat thicknesses than the other sheep and goat breeds due to heavy fat deposition near the dock. Racks from young intact males tended to have higher percentages of lean than racks from aged females within most sheep and goat breeds.

USDA QUALITY GRADES AND PALATABILITY OF LOIN STEAKS FROM CALF AND YOUNG BEEF CARCASSES 1

ABSTRACTThe net effect of increases in one palatability attribute (flavor) and decreases in other palatability attributes (amount of connective tissue; tenderness) as carcass maturity increased from “Calf” to “Beef” was that the composite measures of eating satisfaction (overall palatability ratings) were identical (4.8 and 4.8) for loin steaks from carcasses of the two age classes. Increases in maturity across the range from Ca00 to A33 had no effect (P &gt; 0.05) on palatability of loin steaks; attempts to classify “Calf” vs. “Beef” or to assign relative maturity scores within the Calf class were not successful in identifying differences in palatability of loin steaks. Relative fatness (feathering; flank streaking; marbling; estimated or actual intramuscular fat content; subcutaneous fat thickness) was useful in accounting for the observed variability in palatability of meat from Calf and/or Beef carcasses and should be the basis for quality grade assessments. In no case did consideration of conformation or any relative maturity indicator improve significantly upon ability of relative fatness to explain variation in ratings for flavor, tenderness or overall palatability for loin steaks from either Calf or Beef carcasses. These data suggest that classification of certain bovine carcasses as “Calf” rather than “Beef” could be done more objectively than at present (perhaps for example, by using carcass weight) and that consideration of relative maturity should be eliminated in determining the USDA quality grades of Calf carcasses.

Lamb Carcass Quality. II. Palatability of Rib, Loin and Sirloin Chops

Organoleptic studies of samples from the rib, loin and sirloin of 120 ovine carcasses indicated that individual or combined U.S.D.A. scores for carcass quality (feathering, flank streaking, firmness and maturity) were associated with less than 17% of the variation in palatability ratings. Linear relationships between maturity scores and palatability ratings were not significant, because chops from carcasses of B maturity were not intermediate in organoleptic properties to those from carcasses of A and Y maturity. Carcasses classified B in maturity produced: (a) loin and rib chops which were highly desirable in flavor, (b) loin chops which were rated lowest (P<.05) in juiciness among maturity groups, and (c) less tender (P<.05) rib and loin chops than those from carcasses of A or Y maturity. With the exception of flavor scores for sirloin chops, samples from carcasses of A and Y maturity were similar in palatability ratings. The contribution of increased fatness to flavor, juiciness and tenderness is most accurately related by scores for flank streaking. Neither feathering nor flank firmness contribute significantly to accuracy in predicting palatability when scores for flank streaking are included in a regression equation. Segmentation into U.S.D.A. quality grades indicated that chops from Prime carcasses were superior to those of the other grades in percent of “desirable” ratings for juiciness, tenderness and overall satisfaction. As grade decreased from Prime though Good, there were corresponding decreases in the proportion of chops considered “desirable” in juiciness, tenderness and overall satisfaction. With the exception of scores for tenderness, differences between chops from Good vs. Utility carcasses were of small magnitude.

Lamb Carcass Quality. 1. Palatability of Leg Roasts

Organoleptic studies of 240 ovine leg roasts indicated that individual or combined U.S.D.A. scores for carcass quality (feathering, flank streaking, firmness and maturity) were associated with less than 15% of the variation in ratings for overall satisfaction of leg roasts. Classification according to physiological maturity provided a reasonably consistent indication of ultimate palatability. Leg roasts from carcasses of A maturity exhibited higher ratings for tenderness (P<.05) and overall satisfaction (P<.05) than roasts from carcasses of Y maturity. The contribution of increased fatness to palatability is most accurately reflected by scores for flank streaking. Neither feathering nor flank firmness were significantly related in a positive fashion to the palatability ratings in the present study. Segmentation into U.S.D.A. quality grades indicated that roasts from Prime carcasses sustained the lowest cooking losses; possessed the highest percentage of desirable ratings for juiciness, tenderness, and overall satisfaction and had the lowest percentage of undesirable scores for all of the organoleptic ratings. Small and inconsistent differences appeared between roasts from carcasses in the Choice and Good grades, but leg roasts from Utility carcasses were decidedly inferior in palatability to those from the higher U.S.D.A. grades.