Higher Marbling Scores Research Articles

비육돈의 교배조합이 부분육 생산수율 및 육질에 미치는 영향

ABSTRACT This study was conducted to investigate the effect of the mating system on the retail cut yield and meat quality in pigs. A total of 210 samples were used to estimate meat productivity and meat quality two blocks of two boarlines Duroc (D) and Berkshire (B) were mated to sows of the sowlines Yorkshire ×Landrace (YL) and Berkshire (B). Results showed that YLD (YL×D ) and BD (B×D ) had higher percentages of Boston butt and belly than YLB while it has higher percentages of lean meat yield than YLB (YL×B ). There were no significant differences in crude protein and ash content of pork from different breeds (P>0.05). However, YLB and YLD had higher moisture content in loin and Boston butt than BD (P<0.05). The pH of BD was highest in pork loin and belly (P<0.05). There differences in meat yield, pH and moisture content among the genotypes suggested that pork quality might be affected by the lightness and cooking loss. BD was lowest lightness value (CIE L*) and cooking loss in pork loin among the genotypes (P<0.05). The percentage of saturated palmitic acid (C16:0) in Boston butt (P<0.05) of BD had significant lower, while the percentage of unsaturated palmitoleic (C16:1) and oleic acid (C18:1) had higher in pork loin and belly (P<0.05). Drip and marbling score were found significantly different in genotypes and BD had lower drip and higher marbling score in pork loin and belly (P<0.05). The sensory evaluations indicated that the highest overall acceptability in BD was attained. From the results, BD breed had highest meat quality among crossbred pigs. (

Identification of a Novel SNP Associated with Meat Quality in C/EBP慣 Gene of Korean Cattle

CCAAT/enhancer binding protein a (C/EBPα) plays an important role in lipid deposition and adipocyte differentiation. In order to find genetic markers to improve the meat quality of Korean cattle, the bovine C/EBPa gene was chosen as a candidate gene to investigate its association with carcass and meat quality traits in Korean cattle. A single nucleotide polymorphism (SNP) was identified at position 271 (A/C substitution) of coding region in the C/EBPa gene. A PCR-RFLP procedure with restriction enzyme Smal was developed for determining the marker genotypes. The frequencies of alleles C and A and were 0.374 and 0.626, respectively. The genotype frequencies for CC, AC and AA were 12.9, 49.0 and 38.1%, respectively, in Korean cattle population. The frequencies of genotype were in agreement with Hardy-Weinberg equilibrium. Association analysis indicated that the gene-specific SNP marker of C/EBPa showed a significant association with marbling score (p<0.05). The animals with AA genotype had higher marbling score than those with the AC or CC genotype. Although further studies are needed to validate our results, the C/EBPa gene could be useful as a genetic marker for carcass and meat quality traits in Korean cattle.

Association of SNP Marker in the Thyroglobulin Gene with Carcass and Meat Quality Traits in Korean Cattle

Thyroid hormones play an important role in regulating metabolism and can affect homeostasis of fat depots. The gene encoding thyroglobulin (TG), producing the precursor for thyroid hormones, has been proposed as a positional and functional candidate gene for a QTL with an effect on fat deposition. The SNP occurs in the 5' promoter region of the TG gene and is widely used in marker assisted selection (MAS) programs to improve the predictability of marbling level and eating quality in beef cattle. In this study, we identified three SNPs at the 5' promoter region of the TG gene in Korean cattle. Of the three SNPs identified in TG gene, the C257T and A335G were previously unreported new SNPs. The sequence data were submitted to GenBank (GenBank accession number: AY615525). The previously reported C422T SNP showed three genotypes, CC, CT and TT, by digestion with the restriction enzyme MflI using the PCR-RFLP method. A new allelic variant corresponding to the C→T and A→G mutations at positions 257 and 335, respectively, could be detected by the SSCP analysis. The gene-specific SNP marker association analysis indicated that the C422T SNP marker was significantly associated (p<0.05) with marbling score. Animals with the CC and CT genotypes had higher marbling score than those with the TT genotype. Results from this study suggest that TG gene-specific SNP may be a useful marker for meat quality traits in future MAS programs in Korean cattle.

Diacylglycerol acyltransferase (DGAT) activity in relation to muscle fat content and &amp;lt;i&amp;gt;DGAT1&amp;lt;/i&amp;gt; genotype in two different breeds of &amp;lt;i&amp;gt;Bos Taurus&amp;lt;/i&amp;gt; (short communication)

Abstract. To circumvent the obvious waste of resources when producing good marbled beef, research is needed to clarify mechanisms which are involved in intramuscular fat storage in cattle. The possible association between the activity of diacylglycerol acyltransferase (DGAT) and muscle fat content was examined in samples of longissimus dorsi (LD) and semitendinosus (ST) muscle from Holstein and Charolais bulls. The Holstein bulls exhibited higher fat content in both muscles and higher marbling score. In Holstein, DGAT activity was enhanced in the LD muscle, and there was a tentative positive relationship between DGAT activity and the fat content in ST muscle. When muscle DGAT activity was examined as a function of DGAT1 genotype for all animals, regardless of breed, the DGAT activity of LD muscle of the K/K genotype was about five-fold greater than for either the K/A or A/A genotypes. Further investigation on the relationship between DGAT1 genotype and i.m. fat is required before this may be developed as a selection tool for marbling.

Ascophyllum Nodosum Supplementation Strategies That Improve Overall Carcass Merit of Implanted English Crossbred Cattle

English crossbred steers (n = 32) and heifers (n = 32) were fed a corn- based finishing diet and supplemented with 2% Ascophyllum nodosum on a DM basis to for various feeding stages of the 119 d feeding period determine the supplementation strategy that maximized intramuscular fat deposition as determined by quality grade. All cattle were implanted with Ralgro® on d 36 of the trial and re-implanted with Revalor-S® or Revalor-H® on d 92. Cattle were blocked by sex and divided into one control and three treatment groups receiving Ascophyllum nodosum. Treatment 1 (trt 1) received Ascophyllum nodosum from d 36 to 50 of the feeding period, trt 2 received Ascophyllum nodosum for the last 14 d of the feeding period, and trt 3 which received Ascophyllum nodosum for both d 36-50 and the last 14 d of the feeding period. Cattle were weighted initially (385±4.53 kg) and every 28 d following until they reach an average BW of 554±7.46 kg. No effect for Ascophyllum nodosum supplementation was found on measured performance characteristics. All treatment groups supplemented with Ascophyllum nodosum had higher actual marbling scores (p<0.05) than controls. Trt 1 was found to have a highest marbling score (572.5; p<0.05), whereas the control group having the lowest marbling score (473.8). Trt 1 had a higher quality grade (5.25; p<0.05) than the control (3.94) group, but did not differ from trt 2 (4.56; p = 0.105) and trt 3 (4.75; p = 0.236) where high Select = 4, and low Choice = 5. Trt 2 did not differ from trt 3 (p = 0.655), or the control group (p = 0.140) for quality grade. However, trt 3 did tend to differ (p = 0.057) from the control group for quality grade. Control group animals graded 25% Choice, 62.5% Select; trt 1 graded 75% Choice, 18.8% Select; trt 2 graded 62.5% Choice, 25% Select and trt 3 graded 56.3% Choice and 31.2% Select. Overall, treatment groups had a 39.6% increase in Choice quality grade and a 37.5% decrease in Select quality grade when compared to the control animals.

한우 육성 비육 시 보리 급여수준이 증체와 육질에 미치는 효과

본 연구는 보리의 급여수준이 한우수소의 성장과 육질에 미치는 효과를 조사하고자 실시되었다. 수송아지 20두(평균체중 99㎏)를 공시하여 한우수소의 육성비육 시 보리의 급여수준(육성기－비육전기－비육후기 보리 배합비; 0-0-40, FⅡ40; 0-0-60, FⅡ60; 0-20-40, F2040; 0-20-60, F2040)이 증체와 육질에 미치는 효과를 구명하였다. 시험기간 동안의 체중은 성장단계별 보리 급여수준 간 차이는 보이지 않았으나, FⅡ40구의 24개월령 체중이 591.5kg으로 606.2～614.6kg 내외의 다른 처리구에 비해 다소 감소된 경향이었다. 그러나 FⅡ60구는 비육후기에 보리 60% 첨가된 사료를 섭취하면서 증체가 개선되는 경향이 있었다(P<.19). 한우수소에 대한 보리위주 사료의 급여는 생체중, 도체중과 도체율, 정육률, 거래정육률 그리고 KPH 지방과 뼈의 비율 등의 도체특성에 있어 처리 간 차이는 없었으나, 보리를 비육전기에 20%, 비육후기에 60% 급여한 F2060구의 한우수소에서 정육률과 지방률이 각각 89.82, 20.28%로 다른 처리구에 비해 다소 높았으며, 이로 인해 거래정육률은 최대 5.5% 가량 낮게 나타났다. 근내지방도는 FⅡ40구 및 F2060구에서 각각 3.75, 3.60으로 다른 처리구에 비해 높은 편이었으며, 조직감 역시 FⅡ60구와 F2060구가 공히 1.6으로 다른 두 처리구에 비해 양호하였다. The present study was carried out to determine the effects of feeding levels of barley grain in diets of Hanwoo on the growth performance and carcass characteristics of Hanwoo. Twenty Hanwoo bull calves (initial mean body wt. 99kg) were randomly divided to examine the effects of 5 feeding levels of barley grains(addition levels: 0, 0 and 40% for FII40; 0, 0 and 60% for FII60; 0, 20 and 40% for F2040; and 0, 20 and 60% for F2060 during the growing, early fattening and late fattening periods, respectively) on growth performance and meat quality. Body weight was not affected by the feeding level of barley grains through the whole experimental period, although the body weight of Hanwoo bulls fed FII40 diet at 24 months old of age tended to be lower(591.5kg) than that of other animals(606.2～614.6kg). However, body weight gain in the bulls of the FII60 diet was slightly increased(P<.19). The feeding levels of barley grains did not influence on fasting body weight, carcass weight, carcass rate, lean meat, retailed cut, KPH fat and bone yield. The lean meat yield(89.82%) and fat yield(20.28%) tended to increase in Hanwoo bulls fed the F2060 compared with other treatments. Feeding of the diets of FII40 resulted in the higher marbling scores as 3.75, respectively than other diets.

Effects of marbling and shear force on consumers' willingness to pay for beef strip loin steaks

Experimental economic procedures were used to measure the effects of changes in marbling score and Warner-Bratzler shear force (WBSF) value on consumer purchasing behavior and willingness to pay for beef strip loin steaks (n = 541). Consumers were more likely to bid on a steak during the experimental auction if the steak had a high marbling score or low WBSF value. Averaging across all consumers in the study (n = 489), the predicted odds that consumers would submit a nonzero bid were favorable for steaks with a marbling score greater than Modest(50) or a WBSF value less than 3.9 kg. Bid prices for steaks were analyzed with respect to changes in steak marbling score, WBSF value, quality grade marketing category classification (Select, Low Choice, Premium Choice, and Prime), and WBSF marketing category classification (very tender, <or= 3.4 kg; slightly tender, 3.41 to 4.40 kg; slightly tough, 4.41 to 5.40 kg; or very tough, > 5.40 kg). The percentage of bids that were zero was highest (P < 0.05) for Select steaks, intermediate (P < 0.05) for Low Choice steaks, and lower (P <0.05) for Premium Choice or Prime steaks. Steaks in the very tender category had the lowest (P < 0.05) percentage of zero bids, and steaks in the slightly tough and very tough categories had the highest (P < 0.05) percentage of zero bids submitted from "buyers" in the auction. Premium Choice and Prime steaks were valued higher (P < 0.05) than Select steaks by consumers. On average, Premium Choice steaks received a 0.89 dollars/kg premium, and Prime steaks received a 2.47 dollars/kg premium over the mean bid price for Select steaks. Predicted mean bid prices for steaks decreased by 1.02 dollars/kg for each 1 kg increase in WBSF value. On average, steaks in the very tender marketing category received a higher (P < 0.05) bid price than the bid price for steaks in the slightly tender, slightly tough, and very tough categories (+0.83 dollars/kg, +2.09 dollars/kg, and +2.55 dollars/kg, respectively). Mean bid prices for steaks from the slightly tough and very tough categories did not differ (P = 0.184). Compared with the mean bid price for steaks in the slightly tender category, steaks from the slightly tough and very tough categories were discounted (P < 0.05) by 1.26 dollars/kg and 1.72 dollars/kg, respectively. Results suggest that marbling score and WBSF influence both the probability that consumers will purchase and the price they are willing to pay for strip loin steaks.

Nível de concentrado, variedade da silagem de sorgo e grupo genético sobre a qualidade da carcaça e da carne de novilhos confinados

O efeito de dietas com três níveis de concentrado, associados à silagem de dois híbridos de sorgo, sobre a qualidade da carcaça e da carne de novilhos foi avaliado, utilizando-se 60 animais mestiços com predominância de Charolês ou de Nelore, terminados em confinamento dos 20 aos 22 meses de idade. Os novilhos apresentavam 322 kg de peso inicial e foram distribuídos em delineamento inteiramente casualizado em um esquema fatorial 3 x 2 x 2, ou seja, três níveis de concentrado (25, 35 e 45% da matéria seca da dieta), dois tipos de silagem de sorgo (forrageiro e duplo propósito) e dois grupos genéticos. A interação foi significativa entre tipo de silagem e genótipo somente para a característica quebra ao descongelamento. Animais alimentados com silagem de sorgo forrageiro apresentaram carne de melhor palatabilidade (6,37 ± 0,14 vs 5,74 ± 0,14 pontos), menor perda durante a cocção (26,7 ± 0,8 vs 29,2 ± 0,8%) e de pior coloração (3,49 ± 0,15 vs 4,00 ± 0,15 pontos) que aqueles alimentados com silagem de sorgo duplo propósito. A maciez da carne melhorou à medida que aumentou o nível de concentrado na dieta, com 5,40 ± 0,16; 5,71 ± 0,26 e 6,42 ± 0,23 pontos, respectivamente, para 25, 35 e 45%. O mesmo foi verificado para a conformação de carcaça, com 9,7 ± 0,4; 9,8 ± 0,3 e 10,8 ± 0,4 pontos, citados na mesma ordem. Entre os genótipos, observou-se que novilhos mestiços com predominância de Charolês apresentaram melhor conformação de carcaça (10,8 ± 0,3 vs 9,4 ± 0,3 pontos) e carne mais macia (6,43 ± 0,18 vs 5,26 ± 0,21 pontos), mais suculenta (5,99 ± 0,11 vs 5,60 ± 0,13 pontos), com menor perda ao descongelamento (6,40 ± 0,51 vs 8,69 ± 0,58%) e maior grau de marmoreio (4,76 ± 0,30 vs 3,77 ± 0,34 pontos), enquanto os mestiços com predominância de Nelore apresentaram maior porcentagem de gordura na carcaça (22,3 ± 0,6 vs 18,9 ± 0,5%).

Effects of supplemental rumen-protected conjugated linoleic acid or linoleic acid on feedlot performance, carcass quality, and leptin concentrations in beef cattle.

Thirty-six Angus x Hereford heifers (365 kg) were used to determine effects of dietary lipid supplementation from two sources during the final 32 or 60 d of feeding on serum and adipose tissue leptin concentrations, animal performance, and carcass characteristics. Following an initial feeding period of 56 d, heifers were fed one of three diets in a 3 x 2 factorial arrangement: 1) basal diet, 2) basal diet plus 4% (DM basis) corn oil, or 3) basal diet plus 2% (DM basis) rumen-protected conjugated linoleic acid (a mixture of Ca-salts of palm oil fatty acids with 31% conjugated linoleic acid). Jugular blood samples were collected at 28-d intervals (d 28 to 118) and serum subsequently harvested for leptin quantification via RIA. Real-time ultrasound measurements were collected at 28-d intervals across time on feed. At slaughter, samples were obtained from various adipose depots. Data were analyzed with dietary treatment, length of supplementation, adipose depot (when appropriate), and all two- and three-way (when appropriate) interactions in the repeated measures model. Measures of feedlot performance, including ADG, DMI, and gain:feed did not differ (P > 0.23) with dietary treatment or supplementation length. Heifers supplemented with corn oil tended (P < 0.07) to have higher marbling scores following 32 d of treatment than those supplemented with rumen-protected conjugated linoleic acid, with controls intermediate. Quality grade and hot carcass weight did not differ (P > 0.15) with treatment or length of supplementation. Leptin concentrations were higher (P < 0.05) from d 57 to 118 on feed than the initial period (d 0 to 56) of dietary adaptation when all animals received the basal diet. Circulating leptin concentrations were not affected by dietary treatment. However, leptin concentrations in adipose tissues were greater (P < 0.05) for heifers supplemented with corn oil than either control or rumen-protected conjugated linoleic acid diets, which did not differ. Compared with adipose tissues from rumen-protected conjugated linoleic acid-supplemented animals, tissues from heifers fed corn oil contained 68% greater leptin concentration. Correlations between performance, carcass traits, and serum leptin concentrations were low. Serum leptin concentrations across time on feed were not associated with carcass and performance data, including ADG, DMI, and gain:feed. Based on these data, concentrations of leptin are not related to indices of feedlot performance and carcass quality in beef cattle.

The TG5 thyroglobulin gene test for a marbling quantitative trait loci evaluated in feedlot cattle

The TG5 (thyroglobulin 5′ leader sequence) single nucleotide polymorphism has been associated with marbling in cattle fed for periods longer than 250 days. To test whether the association could be detected in diverse cattle, fed for less than 250 days, and to measure the size of the effect, we sampled 1750 cattle from the AMH Toowoomba feedlot. These cattle were sampled on 28 separate days, over 9 months. Their marbling scores covered the complete range. We found that the TG5 single nucleotide polymorphism was associated with marbling scores (P&lt;0.05) and estimated that TG5 genotypes explained 6.5% of the residual deviance for the marbling phenotype. We also found that the '3' allele was more frequent in animals with higher marbling scores. The consistency of the allelic association between studies and, in particular, the association found in diverse cattle, indicate that the TG5 polymorphism can be used as a breeding tool and possibly a feedlot entry tool. To estimate the size of the genetic region in which the marbling quantitative trait loci are located, we tested the nearby DNA markers CSSM66 and BMS1747. These do not show allelic associations to marbling. The consistency of the allelic association between studies, the lack of association to nearby DNA markers and the complementary information on gene action of genes near Thyroglobulin suggest that DNA sequence variations, in or near the Thyroglobulin gene sequence, are the likely causes for the marbling quantitative trait loci. Further studies of single nucleotide polymorphism in and near the Thyroglobulin DNA sequence should allow causal mutations for the effect to be identified.

Carcass Traits Determining Quality and Yield Grades of Hanwoo Steers

A group of Hanwoo (Korean cattle) steers (n=14,386) was sampled from a commercial abattoir located in Seoul over one year period (spring, summer, autumn and winter) and their carcass traits were collected. Carcass traits assessed by an official meat grader comprised degree of marbling, meat color, fat color, texture and maturity for quality grade, and back fat thickness, ribeye area and carcass weight for yield grade. A heavier carcass with a higher marbling score, more red meat color and white fat color received better quality grade (p<0.05). Regression analysis showed that the marbling score was the strongest attribute (partial R 2 =0.88) for quality grade. Lighter carcasses with a thinner back fat and larger ribeye area received higher yield grade score. The back fat thickness was the most negative determinant of yield grade (Partial R 2 =-0.66). The slaughter season had a little effect on quality and yield grades. As slaughter weight increased, back fat thickness and ribeye area increased linearly, whereas marbling score reached its asymptotic level at approximately 570 kg. As a consequence, quality grade showed a considerable improvement up to 570 kg, but increases in slaughter weight afterward showed a little benefit on quality grade. There was a clear curvilinear relationship between slaughter weight and yield grade in that the yield grade reached its highest point at approximately 490 kg and decreased afterward. These results suggested that 570 kg at the age of 24 months might be the economic slaughter weight for quality grade but 490 kg for yield grade.

Effects of fasting and transportation on pork quality development and extent of postmortem metabolism.

One hundred seventy-seven pigs were used to determine the interaction effects of fasting and length of transport prior to harvest on pork muscle quality. The study design was a 2 x 2 x 3 factorial, which involved two genetic sources, fasting (F) or no fasting (N) of pigs 48-h prior to harvest, and three transport times (0.5, 2.5, or 8.0 h) on a semitrailer to the packing plant. Genetic source was a significant source of variation (P < 0.05) for most composition and muscle quality variables. Fasting reduced hot carcass weight 3.6% (P < 0.05), but length of transport did not affect hot carcass weight (P > 0.05). There were no differences (P > 0.05) in percent lean among fasting and transport treatments. Fasted pigs had higher longissimus dorsi (LD) ultimate pH (pHu), darker lean color, higher marbling score and lower 7-d purge loss, 24-h drip loss, and cooking loss (P < 0.05) than nonfasted pigs. Meat from pigs that were transported 8.0 h had lower glycolytic potential (GP), higher LD and semimembranosus (SM) pHu, darker lean color, and lower L*, 7-d purge loss, 24-h drip loss, cooking loss, and shear force values than meat from pigs transported 0.5 h (P < 0.05). Meat from pigs transported 2.5 h had higher LD and SM pHu and lower L*, 7-d purge loss, 24-h drip loss, and cooking loss than meat from pigs transported 0.5 h (P < 0.05). Meat from pigs transported 8.0 h had higher LD pHu and color scores and lower L* and cooking loss than meat from pigs transported 2.5 h (P < 0.05). The fasting x transport interaction was significant for SM pHu, L*, color score, and drip loss. Fasting improved SM pHu, L*, color score, and drip loss for pigs that were transported 0.5 h (P < 0.05), but when pigs were transported for 2.5 h or 8.0 h, fasting had little or no effect on these muscle quality traits. Fasting lowered GP and increased LD pHu for pigs from the genetic source with the higher initial pork quality (P < 0.05), while fasting had no effect on pork quality for pigs from the genetic source with the lower initial pork quality (P > 0.05). Longer transport times resulted in lower GP and higher LD pHu regardless of genetic source. Fasting and length of transport each had positive effects on pork quality, but length of transport effects was greater in magnitude. When pigs were transported for 0.5 h, fasting for 48 h prior to harvest improved pork quality, but when pigs were transported 2.5 or 8.0 h, fasting had little effect on pork quality.

Influence of outdoor rearing and indoor temperature on growth performance, carcass, adipose tissue and muscle traits in pigs, and on the technological and eating quality of dry-cured hams

The effects of restricted outdoor rearing during winter (W) or summer (S), and the influence of indoor ambient temperature [17 °C (I17) vs. 24 °C (I24), the latter being considered as control] on pig growth performance, carcass, muscular and adipose tissue traits, and technological and eating quality of dry-cured hams were evaluated. I17 pigs exhibited higher, whereas W had similar and S lower growth rates than the controls ( P<0.001). Carcass traits were not different between groups, except in lower back fat weights of S and W pigs ( P<0.01). Decrease in environmental temperature affected the fatty acid composition of the back fat leading to higher MUFA and lower SFA and PUFA contents ( P<0.001) in I17 and W pigs, whereas S pigs exhibited higher PUFA levels ( P<0.001) and fat firmness ( P<0.01) than the controls. Rearing system did not significantly influence the intramuscular fat content of Semimembranosus ( P=0.08), and had no effect on ultimate pH. In the Longissimus lumborum, percentage and relative area of αR fibers increased in W pigs ( P<0.05), but citrate synthase activity did not differ between groups. I17 and W hams exhibited higher processing yields of dry-cured hams than controls ( P<0.05). Sensory analyses showed that pig rearing conditions influenced the product appearance, the I17 and W hams exhibiting lower homogeneity ( P<0.01) and intensity ( P<0.05) of colour, and higher marbling scores ( P<0.01) than I24 hams, but had no influence on texture or flavour.

Early-weaning and postweaning nutritional management affect feedlot performance, carcass merit, and the relationship of 12th-rib fat, marbling score, and feed efficiency among Angus and Wagyu heifers.

Twelve 3/4 Angus (Angus) and 12 Wagyu-cross (1/2 Wagyu x 1/2 Angus) (Wagyu) heifers were weaned at 180 d of age and grazed on endophyte-infected tall fescue for 16 mo before entering the feedlot as 2-yr-olds. Twelve 3/4 Angus heifer calves and 12 Wagyu-cross heifer calves from the following year's calf crop were weaned at 142 +/- 4.1 d of age, immediately adjusted to an 80% concentrate diet, and finished as calves. All heifers were fed a common finishing diet until an estimated 50% of their respective group would grade USDA low Prime or better based on ultrasound predictions. Ultrasound measurements of s.c. and i.m. fat depots were recorded at 60-d intervals throughout the finishing period. Heifers finished as calves had higher (P = 0.02) marbling scores at any given fat thickness and gained more efficiently (P < or = 0.01) at any given marbling score than heifers finished as 2-yr-olds. Gain:feed decreased quadratically (P < or = 0.05) as 12th-rib fat thickness increased for Angus and Wagyu heifers. Gain:feed decreased linearly (P < or = 0.01) for Wagyu calves and quadratically (P < or = 0.01) for Angus calves as 12th-rib fat thickness increased. However, these differences in slope were not different (P = 0.34) as a result of breed among heifers finished as calves. Marbling score increased linearly (P < or = 0.01) as 12th-rib fat thickness increased for Angus and Wagyu heifers finished as 2-yrolds or as calves. However, Wagyu heifers, regardless of age at feedlot entry, had a higher marbling score (P < or = 0.05) at any given 12th-rib fat thickness than Angus heifers. Finishing early-weaned heifers as calves as opposed to 2-yr-olds results in i.m. fat deposition during a period of more efficient growth. Additionally, including Wagyu genetics into the breeding of early-weaned heifers finished as calves or as 2-yr-olds results in higher marbling scores at any 12th-rib fat thickness.

Effects of L-carnitine on nitrogen retention and blood metabolites of growing steers and performance of finishing steers.

Two experiments were conducted to evaluate L-carnitine supplementation to cattle fed grain-based diets. In Exp. 1, seven Angus-cross steers (216 kg) were used in a 7 x 4 incomplete Latin square experiment to evaluate the effects of supplemental L-carnitine on N balance and blood metabolites. Steers were fed a corn-based diet (17.5% CP) at 2.5% of BW. Treatments were 0, 0.25, 0.5, 1.0, 1.5, 2.0, and 3.0 g/d of supplemental carnitine. The 18-d periods included 13 d for adaptation and 5 d for collection of feces and urine. Blood was collected before feeding and 3 and 6 h after feeding on d 18 of each period. Dry matter intakes tended to be highest when 1.5 g/d of carnitine was supplied, but N retention was not affected by carnitine and averaged 29.3 g/d. Plasma carnitine concentrations and urinary excretion increased with increasing carnitine supply, indicating that at least some of the carnitine escaped ruminal degradation and was absorbed by the steers. Plasma concentrations of NEFA demonstrated a treatment x time interaction; they decreased linearly in response to carnitine before feeding but increased linearly in response to carnitine at 6 h after feeding. Serum insulin and plasma glucagon, IGF-I, cholesterol, triglyceride, and amino acids were not affected by carnitine. Plasma concentrations of glucose, glycerol, urea, and beta-hydroxybutyrate all were increased by some of the levels of carnitine supplementation, but results for these measurements did not follow easily described patterns and seemed to be related to differences in DMI. In Exp. 2, 95 crossbred steers (357 kg initial BW) were fed finishing diets (14.5% CP) for 129 d. Diets were based on steam-flaked corn and contained 6% alfalfa and 4% tallow. Feed intakes, gains, and feed efficiencies were not affected by supplementation with 2 g/d L-carnitine. However, steers receiving L-carnitine tended to have fatter carcasses, as indicated by tendencies (P < 0.2) for thicker backfat, higher marbling scores, and higher yield grades. In conclusion, carnitine supplementation did not alter lean deposition in growing steers but it did alter plasma NEFA concentrations of growing steers fed a corn-based diet and also seemed to increase fat deposition in finishing cattle.

Tasco-Forage: III. Influence of a seaweed extract on performance, monocyte immune cell response, and carcass characteristics in feedlot-finished steers.

Tall fescue (Festuca arundinacea Schreb.) infected with the endophyte Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin) causes fescue toxicosis in cattle grazing the forage, but effects of the endophyte were considered to be abated soon after removal of the animals from pastures. Tasco-Forage, a proprietary extract from the brown seaweed Ascophyllum nodosum, is a known source of cytokinins and has increased antioxidant activity in both plants and the animals that graze the forage. Tasco was applied at 0 and 3.4 kg/ha to infected and uninfected tall fescue pastures in Virginia and Mississippi. Forty-eight steers grazed the pastures at each location during each of 2 yr (n = 192) before being transported to Texas for feedlot finishing. On arrival at the feedlot, steers from Tasco-treated pastures had higher (P < 0.01) monocyte phagocytic activity and tended (P < 0.07) to have higher major histocompatibility complex class II expression than steers that grazed the untreated pastures. A depression (P < 0.05) in monocyte immune cell function due to grazing infected fescue was detected throughout the feedlot finishing period but was reversed by Tasco. Rectal temperatures were elevated (P < 0.07) in steers that had grazed the infected tall fescue when they arrived in Texas, but by d 14 no difference was detected. However, by d 28 the temperature effects of infected tall fescue were reversed. Steers that had grazed infected fescue had lower (P < 0.01) rectal temperatures on d 112 of the feedlot period, demonstrating a much longer-lasting effect of the endophyte on thermoregulatory mechanisms than previously thought. Steers that had grazed Tasco-treated pastures had higher (P < 0.01) rectal temperatures on d 56 than steers that had grazed untreated fescue. Steers that had grazed the Tasco-treated pastures had higher marbling scores (P < 0.05) regardless of the endophyte, but no effect of Tasco or endophyte on gain was measured. Our data suggest that Tasco application to tall fescue pastures alleviated some of the negative effects of tall fescue toxicity.

Growth Performance by Stocker Steers Fed Magnesium-Mica During a Grazing and Feedlot Period1,21Contribution No. 00-35-J from the Kansas Agriculture Experiment Station.2Appreciation is expressed to Micro-Lite, LLC, (Chanute, KS) for providing magnesium-mica and partial financial support for the project and to Ronald McNickle, Terry Green, Rick Black, Larry Ellis, and Robert Middleton for assistance with sample collection and animal care.

Abstract Two experiments were conducted to determine the effects of Mg-mica supplementation on grazing and feedlot performance of stocker steers. In Exp. 1, eight groups of six steers were fed a basal diet of 80% ground grain sorghum, 15% corn silage, and 5% control protein supplement (DM basis) or a supplement containing Mg-mica (9% of supplement; 4.5 mg/kg diet DM) for 141 d. Marbling scores tended (P 0.10) higher marbling scores, and a higher percentage of carcasses grading USDA Choice than steers fed the control supplement during the pasture phase. Therefore, adding Mg-mica to pasture supplements or feedlot diets appears to have no impact on grazing or feedlot performance, but may improve carcass quality.

Breed differences and genetic parameters for melting point, marbling score and fatty acid composition of lot‐fed cattle

SummaryFatty acid composition, marbling score and melting point data collected between 1994 and 1996 were analysed. The data were from the adipose tissue of 764 Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu crossbred cattle slaughtered after lot‐feeding at 500 days of age. The aim was to investigate sire‐breed differences and to estimate heritability and genetic and phenotypic correlations. Significant breed differences were found: Jersey crosses had the highest marbling score and Belgian Blue crosses had the lowest. Limousin crosses had the highest melting point and Jersey crosses the lowest. South Devon crosses had the highest proportion of stearate and Jersey crosses the lowest. Desaturation indices in C16 and C18 fatty acids were highest in Jersey crosses and lowest in Limousin and South Devon crosses. In contrast, there were no breed differences in the proportions of palmitate, oleate, total saturated, total mono‐unsaturated fatty acids and elongation index. Heritability estimates of individual fatty acids and their summations, melting point and marbling were low to moderately low (0.05–0.27). Strong genetic correlations of melting point and desaturation index in C16 fatty acids (‐0.93), melting point and stearate (0.62), marbling and stearate (‐0.71) and marbling and desaturation index in C18 fatty acids (0.62) were observed. Phenotypic correlation were generally low. The results imply that fatty acids in the adipose tissue of lot‐fed cattle have a moderately low heritability, hence genetic progress might be slow.

Genetic parameter estimates for serum insulin-like growth factor-I concentration and carcass traits in Angus beef cattle.

Divergent selection for serum insulin-like growth factor-I (IGF-I) concentration began at the Eastern Ohio Resource Development Center (EORDC) in 1989 using 100 spring-calving (50 high line and 50 low line) and 100 fall-calving (50 high line and 50 low line) purebred Angus cows. Following weaning, bull and heifer calves were fed in drylot for a 140-d postweaning period. At the conclusion of the postweaning test, bulls not selected for breeding were slaughtered and carcass data were collected at a commercial abbatoir. At the time of this analysis, IGF-I measurements were available for 1,283 bull and heifer calves, and carcass data were available for 452 bulls. A set of multiple-trait, derivative-free, restricted maximum likelihood (MTDFREML) computer programs were used for data analysis. Estimates of direct heritability for IGF-I concentration at d 28, 42, and 56 of the postweaning period, and for mean IGF-I concentration were .32, .59, .31, and .42, respectively. Direct heritabilities for carcass traits ranged from .27 to 1.0, .26 to 1.0, and .23 to 1.0 when the age-, fat-, and weight-constant end points, respectively, were used, with marbling score having the smallest heritability and longissimus muscle area having the highest heritability in each case. Maternal heritability and the proportion of phenotypic variance due to permanent environmental effect of dam generally were < or = .21 for IGF-I concentrations and for carcass traits other than longissimus muscle area. Additive genetic correlations of IGF-I concentrations with backfat thickness, longissimus muscle area, hot carcass weight, marbling score, quality grade, and yield grade averaged -.26, .19, -.04, -.53, -.45, and -.27, respectively, when carcass data were adjusted to an age-constant end point. Bulls with lower IGF-I concentrations had higher marbling scores and quality grades, but also had higher backfat thickness and yield grades regardless of the slaughter end point. Serum IGF-I concentration may be a useful selection criterion when efforts are directed toward improvement of marbling scores and quality grades of beef cattle.

Effects of carnitine on performance of finishing steers (2000)

Ninety-five crossbred steers (787 lb initial body weight) were fed finishing diets (14.5% crude protein) for 129 days. Diets were based on steam-flaked corn and contained 6% alfalfa and 4% tallow. Steers were supplemented with 2 g per day of L-carnitine, or not supplemented (control). Feed intakes, gains, and feed efficiencies were not impacted by carnitine supplementation. However, steers receiving L-carnitine had fatter carcasses as indicated by tendencies (P<.2) for more subcutaneous fat, higher marbling scores, and higher yield grades. Carnitine supplementation may increase fat deposition and alter carcass quality of finishing cattle.