Effect of anabolic implants on beef intramuscular lipid content.

Sixty ribeye steaks were used to determine the effects of anabolic implants on i.m. lipid composition of beef steers. Steaks were obtained from carcasses (346 kg) of steers assigned to four treatment groups (C = nonimplanted control; ET = 28 mg of estradiol benzoate plus 200 mg of trenbolone acetate on d 0; ET/ET = ET on d 0 and d 61; and S/ET = 20 mg of estradiol benzoate plus 200 mg of progesterone on d 0 and ET on d 61) and fed a high-concentrate diet for 127 d. Total fatty acid content of the longissimus was less (P < .05) for implanted steers. Implanting increased (P < .05) stearic and linolenic acid percentages and reduced (P < .05) oleic acid percentage but did not alter (P > .05) percentages of other fatty acids. These changes translated into increased (P < .05) percentages of saturated fatty acids and reduced (P < .05) monounsaturated fatty acids in the longissimus of implanted steers. However, on a per-steak weight basis, implanting did not alter (P > .05) the amounts of any of the individual fatty acids, but it increased (P < .05) the total cholesterol amount. Implanting with an estrogenic compound first reduced (P < .05) the percentage and total amounts of linoleic and polyunsaturated fatty acids. On a percentage basis, implanting alters fatty acid amounts; however, when the increase in ribeye size with implanting is accounted for and fatty acids are evaluated on a per-steak basis, these differences are not significant.     

不同杂交组合肉牛背最长肌FAS mRNA表达及其对肌内脂肪沉积的影响

为了研究不同杂交组合肉牛肌肉FAS mRNA的表达规律及其对肌内脂肪沉积的影响,本试验选择16月龄的西杂、利杂、利草杂交共43头肉牛为研究对象,饲喂相同营养水平的日粮。于试验的第90、180、270天屠宰取背最长肌,索氏提取法测定肌内脂肪含量,荧光定量PCR方法检测FAS mRNA表达水平,分析不同屠宰阶段FAS mRNA变化规律及其对IMF沉积的影响。结果显示:随着肥育时间的延长,IMF含量呈升高的趋势,并且存在种间差异,利杂牛含量最高;FAS mRNA表达量呈升高趋势,相关分析表明,FAS mRNA表达量与IMF含量呈显著正相关(P0.01)。     

The effects of implant strategy on finished body weight of beef cattle

We summarized experimental data to quantify the change in final BW due to a particular implant strategy when cattle are adjusted to the same final body composition. The database developed for this study included 13 implant trials involving a total of 13,640 animals (9,052 steers and 4,588 heifers). Fifteen different implant strategies were used among these trials, including no implant (control), single implants, and combinations of implants. Individual carcass data collected at slaughter were used to calculate the adjusted final shrunk BW at 28% empty body fat (AFBW) for each treatment group within a trial, then the implant treatments were grouped into categories according to their effect on weight at 28% empty body fat (four groups for steers and two groups for heifers). All differences in AFBW between categories were significant (P < 0.01), indicating an incremental anabolic implant dose response in AFBW over unimplanted animals. Values for AFBW ranged from 520 kg in unimplanted steers to 564 kg in steers implanted and reimplanted with Revalor-S. For heifers, AFBW ranged from 493 kg in unimplanted heifers to 535 kg in heifers implanted and reimplanted with Revalor-H. After accounting for differences in mean BW and composition of gain, implanted steers and heifers had 4.2 and 3.1% higher apparent diet ME values, respectively. Increasing the anabolic implant dose increases the weight at which animals reach a common body composition. This study indicates that anabolic implant response is due to a combination of a reduced proportion of the DMI required for maintenance, reduced energy content of gain, and efficiency of use of absorbed energy.     

肉牛肌内脂肪沉积相关基因的研究

相关基因对肌内脂肪含量的影响,已引起国内外研究人员的广泛关注,尤其是高档肉牛的育种方面。本文就影响肌内脂肪沉积的几个相关基因的发现、表达部位以及对肉牛肌内脂肪沉积的影响进行了综述和展望。     

Production factors that influence the hygienic condition of finished beef cattle

A survey was conducted at five UK abattoirs to trace the source of dirty beef cattle and identify factors in the production chain that contributed to their dirtiness. The Meat Hygiene Service Clean Livestock score categories were used and the animals' histories were traced back to their farm of origin. Comprehensive information was collected relating to the farm, transport and lairage phases for 675 cattle from 85 batches. The mean score of the animals on arrival at the abattoir was 1.57, with 2.8 per cent in categories 3 and 4, and none in category 5. Regression analysis, blocking the data by farm of origin, revealed that age, feed type, coat length, clipping, journey distance and time, and abattoir were the six principal factors that affected the scores. Cattle under 20 months of age were cleaner than older cattle. Dry diets resulted in lower scores than wet diets. 'Shorthair' cattle were cleaner than 'medium' or 'longhair' cattle, and cattle which had been clipped were cleaner than unclipped animals. The cattle which had travelled over 150 miles (15 per cent) were dirtier than the others. Within each abattoir there were variations in score between 1 and 4, and the mean scores of the five abattoirs ranged from 1.19 to 1.76. A significant part of this variation could only be accounted for by unmeasured variables such as abattoir management practice, assessors' categorisations and climate.     

Efficacy of vaginal spaying and anabolic implants on growth and carcass characteristics in beef heifers

Ninety crossbred beef heifers averaging 260 kg were blocked by weight and allotted randomly to 15 pens of six heifers each, with three replicates per treatment. The treatments were spayed heifers (S); intact heifers (I); S + Synovex-H7 (SH); I + Synovex-H (IH); and S + Synovex-S7 (SS). The heifers were spayed vaginally with a Willis instrument; intact heifers were rectally palpated for reproductive soundness. Heifers were fed a growing diet (55 d), re-implanted and subsequently fed a finishing ration (73 or 101 d). All heifers were observed for estrus daily at approximately 0600 and 2000 until d 69. A jugular vein blood sample was obtained from each heifer on d 48, 55, 62 and 69 for blood progesterone analysis. Results of blood progesterone analysis and reproductive tract examination indicated that two spayed heifers were incompletely spayed, a 96% success rate. The SH and SS heifers continued to exhibit estrous behavior despite being successfully spayed. Heifers implanted with Synovex-H had greater (P less than .01) ADG and were more efficient (P less than .03) than nonimplanted heifers. The SS heifers had greater ADG (P less than .05) during the finishing phase than SH heifers, but no advantage of SS over SH was apparent during the growing phase. The overall ADG response to implantation was fourfold greater (P less than .07) in the spayed heifers than in the intact heifers (32 vs 8%). Heifers implanted with Synovex-H had greater adjusted hot carcass weight (P less than .02) and ribeye area (P less than .002) than nonimplanted heifers. For adjusted live weight and ribeye area, the response to implantation was approximately threefold greater in the spayed heifer than the intact heifer. These results demonstrate that spaying and implanting heifers can increase rates and efficiency of gain even though behavioral estrus is not eliminated.     

Determination of saleable product in finished cattle and beef carcasses utilizing bioelectrical impedance technology

Two experiments were performed to develop prediction equations of saleable beef and to validate the prediction equations. In Exp. 1, 50 beef cattle were finished to typical slaughter weights, and multiple linear regression equations were developed to predict kilograms of trimmed boneless, retail product of live cattle, and hot and cold carcasses. A four-terminal bioelectrical impedance analyzer (BIA) was used to measure resistance (Rs) and reactance (Xc) on each animal and processed carcass. The IMPS cuts plus trim were weighed and recorded. Distance between detector terminals (Lg) and carcass temperature (Tp) at time of BIA readings were recorded. Other variables included live weight (BW), hot carcass weight (HCW), cold carcass weight (CCW), and volume (Lg2/Rs). Regression equations for predicting kilograms of saleable product were [11.87 + (.409 x BW) - (.335 x Lg) + (.0518 x volume)] for live (R2 = .80); [-58.83 + (.589 x HCW) - (.846 x Rs) + (1.152 x Xc) + (.142 x Lg) + (2.608 x Tp)] for hot carcass (R2 = .95); and [32.15 + (.633 x CCW) + (.33 x Xc) - (.83 x Lg) + (.677 x volume)] for cold carcass (R2 = .93). In Exp. 2, 27 beef cattle were finished in a manner similar to Exp. 1, and the prediction equations from Exp. 1 were used to predict the saleable product of these animals. The Pearson correlations between actual saleable product and the predictions based on live and cold carcass data were .91 and .95, respectively. The Spearman and Kendall rank correlations were .95 and .83, respectively, for the cold carcass data. These results provide a practical application of bioelectrical impedance for market-based pricing. They complement previous studies that assessed fat-free mass.     

Structural changes in intramuscular connective tissue during the fattening of Japanese black cattle: effect of marbling on beef tenderization

We investigated changes in structures and mechanical properties of the intramuscular connective tissue during the fattening of Japanese Black steers, using the cell maceration method for scanning electron microscopy. During the early fattening period, from 9 to 20 mo of age, collagen fibrils of the endomysium in longissimus muscle associated more closely with each other, and collagen fibers in the perimysium increased in thickness and their wavy pattern became more regular. These changes were closely related to the increase in mechanical strength of the intramuscular connective tissue and resulted in a toughening of the beef during the period. The shear force value of longissimus muscle decreased after 20 mo of age, concomitantly with the rapid increase in the crude fat content. Scanning electron micrographs of the longissimus muscle dissected from 32-mo-old steers clearly showed that the adipose tissues were formed between muscle fiber bundles, that the honeycomb structure of endomysia was partially broken, and that the perimysium separated into thinner collagen fibers. In semitendinosus muscle, in which the crude fat content was lower (P<.05) than that in longissimus muscle, the structure of the intramuscular connective tissue remained rigid at 32 mo of age. The shear force value of the muscle increased even in the late fattening period, from 20 to 32 mo of age. Thus, the development of adipose tissues in longissimus muscle appears to disorganize the structure of the intramuscular connective tissue and contributes to tenderization of highly marbled beef from Japanese Black cattle during the late fattening period.     

The effect of Tritrichomonas foetus infection on calving rates in beef cattle

SUMMARY The effect of Tritrichomonas foetus var. brisbane infection on calf production by Hereford cows was determined. The mean number of calves produced by cows that were kept continuously with bulls infected with T. foetus for 3 years was 17.6% less than the mean number produced by cows kept with a non-infected bull. Losses in production due to trichomoniasis occurred each year, but were greatest in the first 2 years in cows experiencing infection for the first time.     

Copper and lipid metabolism in beef cattle: a review

Results from experiments investigating Cu metabolism in ruminants indicate that Cu is involved in lipid metabolism. Copper supplementation ranging from 10 to 40 mg of Cu/kg of DM to high-concentrate finishing diets decreased subcutaneous adipose tissue deposition and decreased cholesterol concentrations but increased unsaturated fatty acid composition of LM. Serum norepinephrine tended to be greater in Cu-supplemented steers after a 24-h feed withdrawal and at 2 h postfeed consumption, potentially explaining the reduction in subcutaneous adipose tissue deposition. However, when exogenous norepinephrine was administrated, serum NEFA concentrations were less in Cu-supplemented steers, possibly due to the nonsupplemented control steers having a greater subcutaneous adipose tissue depth at slaughter relative to Cu-supplemented steers. Furthermore, in vitro basal and epinephrine-stimulated lipolytic rates of subcutaneous adipose tissue were greater in Cu-supplemented steers relative to controls. These data indicate that that Cu may influence lipogenic or lipolytic function in subcutaneous adipose tissue. In an attempt to further investigate the effect of Cu on lipid metabolism, lipogenic, lipolytic, and homeostatic mechanisms related to Cu are currently being studied. Recent data indicate that genes involved in bovine liver Cu homeostasis are correlated with Cu transporter protein gene expression in the bovine liver. Therefore, the overall intent of this review is to discuss possible mechanisms whereby Cu may affect lipid metabolism in ruminants.     

广西西门塔尔肉牛超数排卵效果观察

[目的]为了分析广西牛超数排卵技术实施现状,[方法]试验设计在广西宾阳、都安、大化、崇左等4个肉牛养殖场(4组)各选择16头西门塔尔成年母牛作为试验母牛,采用孕酮栓(GIOB)+促卵泡素(FSH)+氯前列烯醇(PGF2)的方法对试验母牛进行超数排卵,观测试验母牛获得总胚胎数、可用胚数、一级胚数,分析超数排卵效果.[结果...     

Dose and release pattern of anabolic implants affects growth of finishing beef steers across days on feed

Four experiments evaluated the effect of implant dose and release pattern on performance and carcass traits of crossbred beef steers. In Exp. 1, steers (4 to 7 pens/treatment; initial BW = 315 kg) were fed an average of 174 d. Treatments were 1) no implant (NI); 2) Revalor-S [120 mg of trenbolone acetate (TBA) and 24 mg of estradiol 17β (E(2)); REV-S]; 3) Revalor-IS followed by REV-S (cumulatively 200 mg of TBA and 40 mg of E(2); reimplanted at 68 to 74 d; REV-IS/S); and 4) Revalor-XS (200 mg of TBA and 40 mg of E(2); REV-X). Carcass-adjusted final BW was greater (P < 0.05) for REV-X and REV-IS/S than for REV-S (610, 609, and 598 kg, respectively). Daily DMI did not differ (P > 0.10) among the 3 implants, but carcass-adjusted G:F was greater (P < 0.05) for REV-X and REV-IS/S than for REV-S (0.197 and 0.195 vs. 0.188). Both HCW and LM area were greater (P < 0.05) for REV-X and REV-IS/S than for REV-S. Marbling scores were greatest (P < 0.05) for REV-S and least (P < 0.05) for REV-IS/S; REV-X was intermediate to NI and REV-IS/S. In Exp. 2, steers (10 pens/treatment; initial BW = 391 kg) were fed 131 d, with treatments of REV-S, REV-IS/S (reimplanted at 44 to 47 d), and REV-X. Carcass-adjusted final BW (598 kg), ADG (1.6 kg), DMI (9.4 kg), G:F (0.17), and HCW did not differ (P > 0.10) among treatments. The percentage of Choice was less (P < 0.05) and percentage of Select greater (P < 0.05) for REV-IS/S than for REV-S and REV-X. In Exp. 3, steers (10 pens/treatment; initial BW = 277 kg) were fed 197 d and received either REV-IS/S (reimplanted at 90 to 103 d) or REV-X. Carcass-adjusted final BW (625 vs. 633 kg) and ADG (1.81 vs. 1.76 kg) were greater (P < 0.05) for REV-X-implanted steers. Daily DMI did not differ, but G:F tended (P < 0.10) to be increased and HCW was greater (P < 0.05) for REV-X than for REV-IS/S. In Exp. 4, steers (8 pens/treatment; initial BW = 238 kg) were fed 243 d and received either REV-IS/S (reimplanted at 68 to 71 d) or REV-X. Carcass-adjusted final BW (612 kg), ADG (1.54 kg), DMI (7.55), and G:F (0.21) did not differ (P > 0.10) for REV-IS/S and REV-X-implanted steers. Carcass traits did not differ among implants, but the percentage of Choice carcasses was greater (P < 0.05) and percentage of Select was less (P < 0.05) for REV-X than for REV-IS/S. These data indicate that when TBA/E(2) dose is equal, the altered release rate of REV-X can improve performance and quality grade, but these effects depend on duration of the feeding period and timing of initial and terminal implants.     

The effect of intramuscular injection of dinoprost or gonadotropin-releasing hormone in dairy cows on beef quality

Intramuscular injections of drugs and vaccines cause tissue damage and subsequent effects on tenderness and consumer acceptability of beef. In the 2007 National Market Cow and Bull Beef Quality Audit, 100% of plants reported fabricating subprimal cuts such as rib eyes and tenderloins from cow and bull carcasses. Dairy beef quality should therefore be a consideration when injections are given to dairy animals. The discussion about injection site reactions and tenderness has focused on vaccines and antimicrobial drugs with little concern for the effects of reproductive hormones. The objective of this study was to quantify antemortem the effects of semimembranosis/semitendinosis muscle injection of dinoprost and GnRH in lactating dairy cows by estimating the weight of tissue damaged and comparing that with a drug known to cause extensive tissue damage, flunixin meglumine. Tissue damage was estimated from previously reported equations for grams of muscle tissue damage based on area under the curve of serum concentrations of the muscle enzyme creatine kinase over time. Dinoprost and flunixin injection both caused a significantly increased estimate of muscle tissue damaged compared with needle only (P = 0.0351 and 0.0355, respectively). Dinoprost and flunixin caused a marginally significant increased muscle tissue damage compared with GnRH (P = 0.1394 and 0.1475, respectively). No statistically significant difference was found between the estimated weight of muscle tissue damaged by flunixin compared with dinoprost (P = 1.0000), or by saline compared with GnRH (P = 0.7736) or needle only (P = 0.4902). The assumption that reproductive hormones are less damaging than vaccines and antimicrobial drugs should be examined more closely, including postmortem evaluation of injection site lesions and effects on tenderness.     

The effect of turn-out to pasture on blood plasma iron concentrations in beef cattle

Beef cows, bred to calve in the spring, were housed indoors over the winter. On May 25, 48 of the cows, and their calves, were put out to pasture while the other 24 cows and calves remained confined.Plasma iron concentrations in the pasture cows were higher (P<0.01) than the levels of the barn cows for several weeks after turn-out, but in September there was no difference (P>0.05). In contrast, the pasture calves showed significantly lower (P<0.01) levels than did the barn calves during the first two weeks, however, there was no difference (P>0.05) in September. No difference in plasma iron levels between male and female calves was found.     

肉牛同期发情效果影响因素的研究

[目的]为了研究同期发情处理方法、繁殖状况、品种、体重等对肉牛同期发情效果的影响,[方法]选择140头不同繁殖状况、品种、体重的肉牛,随机分为3组,分别采用CIDR+第10天肌注PMSG+第11天肌注PGF_2α（埋栓Ⅰ组）、CIDR+第9天肌注PMSG+第11天肌注PGF_2α（埋栓Ⅱ组）、肌注PGF_2α+PMSG(PGF_2α组)的方法进行同期发情处理。[结果]3种不同处理方法相比,PGF_2α组发情率为87.10%,埋栓Ⅰ组、Ⅱ组母牛发情率分别为97.83%、98.41%,显著高于PGF_2α组（P<0.05）;PGF_2α组处理牛受胎率为83.87%,埋栓Ⅰ组、Ⅱ组处理牛受胎率分别为89.13%、84.13%,高于PGF_2α组,但差异不显著（P>0.05）;育成牛与经产牛发情时间相比,埋栓组12～24 h内出现发情症状的经产牛占比为27.27%,育成牛占比为60%,显著高于经产牛（P<0.05）,2...     

Effects of intramuscular fat deposition on the beef traits of Japanese Black steers (Wagyu)

Effects of intramuscular fat deposition on the chemical composition, tenderness, and free amino acids (FAA) concentration of beef were studied using various classified carcasses of 21 Japanese Black (Wagyu) steers. The Beef Marbling Standard (BMS) No., judged on the market in 1998, and fat content, ranged from 2 to 10 and 4.8 to 39.0% in the M. longissimus thoracis, respectively. Moisture content was negatively correlated with the fat content (r =?0.98, P < 0.01). In contrast, protein content was relatively constant up to approximately 23% fat, corresponding to BMS No.4, and decreased as the fat content increased. Cooking loss was also constant up to approximately 28% fat, corresponding to BMS No.4, and markedly decreased with fat content increase. The beef in these cases were, however, classified into BMS No. around 9 and 11, respectively, according to the BMS model in 1988. A negative correlation was found between the shear‐force value and the fat content (r =?0.83, P < 0.05). Most FAA concentrations on the wet weight of meat were correlated negatively with the fat content, except glutamine, and this negative relationship was still observed when the concentrations were recalculated on the basis of protein. These results indicate that higher marbling Wagyu beef (above approx. 23% fat) would have an extremely lower content of protein, which would partly explain the lower cooking loss and FAA with fat increase. In addition, some other reasons not relating to protein content (e.g. high fat content preventing the breakdown of protein to FAA) seem to explain the negative correlation between fat and FAA.     

Relationship of fatty acid composition to intramuscular fat content in beef from crossbred Wagyu cattle.

The deposition of i.m. fat, or marbling, in cattle is recognized as a desirable carcass trait in North American beef grading schemes. In order to investigate the relationship between degree of marbling and fatty acid composition of whole bovine muscle, we extracted the total lipid from pars costalis diaphragmatis (PCD) (n = 23) and longissimus (n = 36) muscles from Wagyu crossbred cattle that were assigned Canadian Grading Agency marbling scores ranging from 1 to 8 on an inverse 10-point scale (i.e., a score of 1 indicated "very abundant" marbling and a score of 10 would be assigned to a carcass "devoid" of marbling). Fatty acid methyl esters (FAME) of the total lipid and triacylglycerol fractions were resolved and quantified through GLC. Marbling scores were negatively associated with total lipid from both PCD (r = -.57, P < .01) and longissimus (r = -.80, P < .001). Differences between PCD and longissimus were found for almost all FAME studied from both lipid fractions, but no differences (P > .05) were seen when the monounsaturated:saturated fatty acid (MUFA/SFA) ratios were compared. Heifers had higher (P < .05) oleic acid content and lower (P < .05) palmitic acid content in lipid extracted from both muscles, resulting in higher (P < .05) MUFA/SFA ratios than those for steers. The relative amount of myristic acid increased as the lipid content (total lipid and triacylglycerol) increased in either longissimus (r values from .48 to .55; n = 36; P < .01) or PCD muscles (r from .67 to .76; n = 23; P < .001). The relative amount of linoleic acid (cis-9, cis-12 isomer) from total lipid was negatively associated with all chemical measurements of lipid from the longissimus (r from -.52 to -.64; n = 36; P < .001) and PCD muscles (r from -.75 to -.85; n = 23; P < .001). This association was not significant (P > .1) for either muscle when linoleic acid from the triacylglycerol fraction was examined, suggesting the negative association between this fatty acid and lipid content was due to a dilution of membrane phospholipids with increasing triacylglycerol. Indices of fatty acid elongase activity, calculated from FAME data, implicated the balance between this enzyme activity and fatty acid synthase as a source of variation between animals displaying various degrees of marbling and worthy of further investigation to better understand the process of marbling fat deposition in beef cattle.