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The common practice in North American feedlot industries is to add antibiotics to the diet to prevent disease and improve both BW gain and feed efficiency. In this study, 240 crossbred steer calves were backgrounded on a 54% silage diet for 80 d and fed a finishing diet consisting of 81% barley grain, 10% barley silage, and 7.5% supplement (DM basis) with and without in-feed antibiotics for approximately 120 d. Calves were assigned to 1 of 5 treatments: a control with no antibiotics, 11 mg/kg of chlortetracycline, 44 mg/kg of chlortetracycline, 44 mg/kg of chlortetracycline plus 44 mg/kg of sulfamethazine, and 11 mg/ kg of tylosin phosphate. A combination of GLC and silver-ion HPLC methods was used to analyze the fatty acid composition of brisket adipose tissue, with emphasis on trans-18:1 and CLA isomers. The inclusion of nonionophore antibiotics in the diet had little effect on the fatty acid composition, except that feeding either 44 mg/kg of chlortetracycline or 11 mg/kg of tylosin caused small increases in 9c-14:1 and 16:0 relative to the control (0.26 and 0.9 g/100 g of total fatty acids, respectively). Likewise, profiles of trans-18:1 and CLA isomers were unchanged by antibiotics, but across treatments the predominant trans-18:1 isomer was 10t-18:1 (where t = trans; 3.22%) at 3 times the concentration of the second most abundant isomer (11t-118:l; vaccenic acid, 1.05%). Rumenic acid (9c,11t-18:2, where c = cis) was the major CLA isomer at 61% of total CLA, followed by 7t,9c-18:2 at 9%. Because no other effects on fatty acid composition were evident, data for trans-18:1 and CLA were pooled across treatments to investigate possible relationships among rumen PUFA metabolites. The total trans-18:1 content in brisket adipose tissue was positively correlated with 10t-18:l, but not with 11t-18:l, whereas the total CLA was positively correlated with 9c,11t-18:2, but not with 7t,9c-18:2. The 7t,9c-18:2 was, however, positively correlated with 10t-18:l and 6t/7t/8t-18:1 but was negatively correlated with rumenic acid. These metabolic interrelationships suggest the presence of bacterial populations with distinct pathways for PUFA biohydrogenation in which either 10t-18:l or 11t-18:1 predominate. Overall, the nonionophore antibiotics tested did not appreciably change adipose tissue composition and consequently could not be used to improve the trans-18:1 or CLA profile (i.e., increase vaccenic and rumenic acids at the expense of 10t-18:l). Key words: adipose tissue, antibiotic, beef, conjugated linoleic acid, trans-18:1

A 2 x 2 factorial experiment with 48 crossbred steers (with Hereford, Angus, and Charolais genetics, and an initial BW of 373 [+ or -] 8.4 kg) was conducted to evaluate the effects of dietary sunflower seeds (SS) and tylosin phosphate (TP) on production factors, carcass characteristics, liver abscess incidence, and fatty acid composition of the muscle (pars costalis diaphragmatis; PCD) and subcutaneous fat. Individually penned steers were fed either a control diet of 84.5% rolled barley, 14% barley silage, and 1.5% mineral and vitamin mix on a DM basis, or an SS diet, in which SS replaced 15% of the diet. Half the animals fed each diet received TP at 11 mg/kg of DM as a top dressing. Interactions were significant for all production factors. A reduction (P = 0.008) in DMI was observed from 10.1 [+ or -] 0.4 kg/d, in steers fed the control diet, to 8.9 [+ or -] 0.3 and 8.6 [+ or -] 0.3 kg/d, in steers fed the SS and SS + TP diets, respectively. Greater (P = 0.014) ADG was observed for steers fed the control diet than for those fed the SS or SS + TP diet (1.4 vs. 1.1 and 1.2, SE = 0.1 kg/d, respectively); however, G:F ratios were greater (P = 0.011) in steers fed the control diets than in those fed the SS diets. Steers fed the control and SS diets had the heaviest and lightest HCW (347 [+ or -] 6.9 vs. 325 [+ or -] 8.4 kg; P = 0.025), respectively. Lean meat yield (%) of steers fed SS was greater (P = 0.117) than in steers fed the control diets, whereas total lean yield [(HCW x lean meat yield)/100] was similar (P = 0.755). Provision of the SS or SS + TP diet eliminated (P = 0.08 for interaction) liver abscesses compared with the 36 and 9% incidence in steers fed the control or control + TP diet, respectively. Fatty acid weight percentages (wt%) followed similar patterns in PCD and subcutaneous fat. Feeding the SS diets led to greater (P = 0.001) wt% of 18:0 and 18:2n-6, but reduced the wt% of 16:0, 9-cis (c)-18:1, and 18:3n-3 in PCD compared with that in steers fed the control diets, but the wt% of 9c, 11-trans (t), and 10t, 12c CLA were increased (P = 0.001) by 36 and 400% in PCD. Dietary SS increased (P < 0.001) the wt% of trans-18:1 isomers. The 10t-18:1 and 11t-18:1 isomers were the greatest, but dietary TP elevated (P = 0.004) only 10t-18:1, and total trans-18:1 (excluding 11t-18:1) was 0.47 [+ or -] 0.06 g/100 g of PCD. Dietary SS for finishing steers reduced the incidence of liver abscesses without affecting total lean yield of the carcass, with modest increases in trans fatty acids and in potentially beneficial fatty acids (11t-18:1 and CLA). Key words: carcass characteristic, conjugated linoleic acid, liver abscess, sunflower seed, trans fatty acid

The value of sunflower seed (SS) in finishing diets was assessed in two feeding trials. In Exp. 1, 60 yearling steers (479 [+ or -] 45 kg) were fed five diets (n = 12). A basal diet (DM basis) of 84.5% steam-rolled barley, 9% barley silage, and 6.5% supplement was fed as is (control), with all the silage replaced (DM basis) with rolled SS, or with grain:silage mix replaced with 9% whole SS, 14% whole SS, or 14% rolled SS. Liver, diaphragm, and brisket samples were obtained from each carcass. In Exp. 2, 120 yearling steers (354 [+ or -] 25 kg) were fed corn- or barley-based diets containing no SS, high-linoleic acid SS, or high-oleic acid SS (a 2 x 3 factorial arrangement, n = 20). Whole SS was included at 10.8% in the corn-based and 14% in the barley-based diets (DM basis). In Exp. 1, feeding whole SS linearly increased DMI (P = 0.02), ADG (P = 0.01), and G:F (P = 0.01). Regression of ME against level of whole SS indicated that SS contained 4.4 to 5.9 Mcal ME/kg. Substituting whole for rolled SS did not significantly alter DMI, ADG, or G:F (8.55 vs. 8.30 kg/d; 1.36 vs. 1.31 kg; and 0.157 vs. 0.158, respectively). Replacing the silage with rolled SS had no effect on DMI (P = 0.91) but marginally enhanced ADG (P = 0.10) and improved G:F (P = 0.01). Dressing percent increased linearly (P = 0.08) with level of SS in the diet. Feeding SS decreased (P < 0.05) levels of 16:0 and 18:3 in both diaphragm and subcutaneous fats, and increased (P = 0.05) the prevalence of 18:1, 18:2, cis-9,trans-11-CLA and trans-10,cis-12-CLA in subcutaneous fat. In Exp. 2, barley diets supplemented with high-linoleic SS decreased DMI (P = 0.02) and ADG (P = 0.007) by steers throughout the trial, whereas no decrease was noted with corn (interaction P = 0.06 for DMI and P = 0.01 for ADG). With barley, high-linoleic SS decreased final live weight (554 vs. 592 kg; P = 0.01), carcass weight (329 vs. 346 kg; P = 0.06), and dressing percent (58.5 vs. 59.4%; P = 0.04). Steers fed high-linoleic SS plus barley had less (P < 0.05) backfat than those fed other SS diets. No adverse effects of SS on liver abscess incidence or meat quality were detected. Although they provide protein and fiber useful in formulating finishing diets for cattle, and did improve performance in Exp. 1, no benefit from substituting SS for grain and roughage was detected in Exp. 2. Because of unexplained inconsistencies between the two experiments, additional research is warranted to confirm the feeding value of SS in diets for feedlot cattle. Key Words: Beef, Fat, Feedlots, Oil, Performance, Sunflower Seeds

The objective was to evaluate chemical, mechanical, and sensory attributes associated with tenderness in divergent cattle breeds--Wagyu (W; n = 12), Limousin (L; n = 12) and Fl-cross (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil (DM basis)). A randomized complete block repeated measures design in a 3 x 2 factorial arrangement of treatments was used, and effects of breed, diet, block, and associated interactions were tested. Cattle were fed barley-based diets for an average of 259 d. Twenty-four hours postmortem (PM), steaks from the longissimus muscle (LM) were sliced, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d PM) at 2[degrees]C, and frozen (-40[degrees]C) until analyzed. Wagyu steaks had lower (P < 0.05) Warner-Bratzler shear force (WBSF) values than L steaks across all aging times. At 1 d PM, W steaks required slightly more (P > 0.05) force to shear than WxL or L (0.30 and 0.11 kg, respectively); however, by d 14 PM, W steaks required 0.77 kg less (P < 0.05) force to shear than L. Wagyu steaks received higher (P < 0.05) sensory panel sustained tenderness scores at d 14 PM than L. The pH decline was slower (P < 0.05), and temperature decline more (P < 0.05) rapid, in W carcasses than L or WxL carcasses. Breed and diet did not affect (P > 0.10) free calcium levels (FCL) over time (0, 1, 3, 7, and 14 d PM), 0-h calpastatin activity (CA), d-1 percent collagen (OH-PRO), or d-1 collagen cross-linking (HP). Western blot analysis for the presence of the troponin-T (TNT) 30-kDa fragment, conducted only on samples from steers fed the 0% sunflower oil diet, demonstrated more proteolysis by d 3 PM in L than W or WxL. Overall, breed differences in mechanical and sensory measures of tenderness were not explained by FCL, CA, OH-Pro, and HP. Even though the initial appearance of the TNT 30-kDa fragment was greater in L, linear slopes for appearance of TNT degradation product across aging time were greater for W and WxL (P < 0.01 and P = 0.056, respectively) than for L, suggesting that tenderness differences due to breed may have been facilitated by more-rapid proteolytic degradation over time. Key Words: Beef, Collagen, Limousin, Tenderness, Troponin-T, Wagyu

The objective of this studywas to evaluate attributes in semitendinosus muscle (ST) associated with tenderness in divergent breeds--Wagyu (W; n = 12), Limousin (L; n = 12), and Wagyu x Limousin cross cattle (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil, DM basis). A randomized complete block repeated measures design with a 3 x 2 factorial arrangement of treatments was used to measure effects of breed, diet, block, and associated interactions. Cattle were fed barley-based diets for an average of 259 d. Temperature and pH were measured at 0, 1, 3, 6, 12, and 24 h postmortem (PM). Steaks from the ST were removed 24 h postmortem, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d postmortem) at 2[degrees]C, and frozen (-40[degrees]C) until analyzed. Dietary treatment did not (P > 0.10) affect Warner-Bratzler shear force (WBSF), collagen amount (OH-PRO) or cross-linking (HP), temperature, or pH. Steaks from WxL aged 14 d postmortem had lower (P < 0.05) WBSF values than L (W were intermediate). Cooking time was longer (P < 0.01) in W and WxL than in L; however, breed did not affect (P > 0.10) cooking loss. Cooking time was not influenced by diet, but steaks from cattle fed 6% sunflower oil had lower (P < 0.05) cooking losses. Temperature decreased more (P < 0.05) rapidly, and pH more slowly (P < 0.05), in W and WxL than L in the first 24 h postmortem. Limousin steaks were lighter (higher L*) and more yellow (higher b *) in color than steaks from W and WxL (P < 0.05). The control diet (no oil added) resulted in steaks that were lighter (P < 0.05) than the treatment diet (6% added sunflower oil). Neither breed nor diet affected (P > 0.10) OH-PRO or HP concentration. The results of this study indicate that biological type differences may not be as great in the ST as in longissimus muscle; thus, to increase tenderness in ST, emphasis may need to be placed on processing and cooking techniques rather than genetic selection. Key Words: Beef, Connective Tissue, Limousin, Semitendinosus, Tenderness, Wagyu

Contents The objective of the present study was to characterize changes in serum metabolic hormones concentrations from 20 weeks before to 20 weeks post-puberty in bulls and to investigate the associations of metabolic hormones concentrations with testicular development. Leptin concentrations increased from 16 weeks before puberty to 8 weeks post-puberty and insulin concentrations increased from puberty to 8 weeks post-puberty. Growth hormone concentrations decreased after 4 weeks post-puberty, whereas IGF-I concentrations increased from 8 weeks before puberty to 8 weeks post-puberty. During this period, testicular growth was accelerated and testosterone secretion increased substantially, without any significant changes in gonadotropin secretion. Monthly circulating concentrations of leptin, IGF-I and insulin accounted for 63% of the variation in scrotal circumference and 59% of the variation in paired testes volume. In conclusion, the secretion of metabolic hormones was not associated with changes in gonadotropins concentrations. Furthermore, the associations of leptin, IGF-I and insulin concentrations with testes size indicated that these hormones might be involved in a gonadotropin-independent mechanism regulating the testicular development in peripubertal bulls. [ABSTRACT FROM AUTHOR]

Abstract: Two experiments in a 2×2 factorial design were conducted with weaned lambs to determine the effects of supplementing either high forage (Experiment 1; 140d) or grain (Experiment 2; 70d) diets containing either 12 or 16% protein without or with sunflower seed (SS) supplement (14% of diet dry matter [DM]) on plasma cholecystokinin (CCK) concentration, and on absolute viscosity, protein, starch and fat content, and amylase activity in digesta collected from different parts of the small intestine. There were four treatment groups in each experiment with 11 or 12 lambs (five or six wethers and six ewes) per treatment group in Experiments 1 and 4, 8-lamb (ewes only) groups in Experiment 2. Each group was fed one of four experimental diets based on corn silage, corn grain and soybean meal in Experiment 1, and on barley grain, straw and soybean meal in Experiment 2. Soybean meal was used to achieve the appropriate concentration of dietary protein in both experiments, while straw was used in Experiment 2 to achieve equal dietary fiber in all diets. Concentrations of CCK were determined in jugular plasma obtained from each lamb (4h after feeding) 6 weeks after the initiation of the experiment. After the end of the experiments all lambs were sacrificed and the digesta sampled within 15min of slaughter from 50cm sections of proximal, mid jejunal and distal small intestine. In Experiment 1, dietary SS increased (P&#60;0.05) plasma CCK concentrations of ewe lambs fed the high protein diet, but reduced (P&#60;0.05) digesta viscosity to 45.2±14.4cP from 226.0±70.2cP across all intestinal sections in all lambs fed the low protein diets. In lambs fed the low protein diet with SS, digesta fat content was increased across all sections. Digesta protein content was 61.9±8.22% in ewe lambs fed the high protein diet in proximal intestinal sections relative to 38.9±7.08% in lambs fed the low protein diet but neither dietary protein nor supplementation with SS had any effect on the amylase activity (¿M reducing sugars released g-1DMmin-1). In Experiment 2, dietary SS decreased (P&#60;0.05) viscosity of small intestinal digesta of lambs to 3.2±32.6cP, in the distal regions of lambs fed the low protein diets relative to those receiving no SS (348±79.8cP). Small intestinal digesta protein was higher (P&#60;0.05) in lambs fed high protein diets with SS and the amylase activity as ¿M reducing sugars released g-1DMmin-1 was increased (P&#60;0.05) in these animals as well. Dietary SS was effective in altering digesta viscosity and protein content in lambs irrespective of protein content of the diet, but the activity of the amylase was substantially increased by higher dietary protein in the barley grain based diets. [Copyright &y& Elsevier]

The effect of breed and diet on insulin response to glucose challenge and its relation to intramuscular fat deposition was determined in 36 steers with 12 each of greater than 87% Wagyu (referred to as Wagyu), Wagyu × Limousin, and Limousin breeds. Weaned steers were blocked by weight into heavy, medium, and light calves and placed in six pens with two pens per weight type and with two steers of each breed per pen. Three pens with steers from each weight class were fed backgrounding and finishing diets for 259 d, while the other three pens were fed the same diets where 6% of the barley grain was replaced with sunflower oil. Prior to initiation of the finishing phase of the study the intravenous glucose tolerance test (IVGTT) was conducted in all steers. Once steers were judged as carrying adequate 12th-rib fat, based on weight and days on feed, they were harvested and graded and samples of the longissimus muscle were procured for determination of fat content and fatty acid composition. Dietary oil improved (P = 0.011; 0.06 ) ADG and feed conversion efficiency of steers during the latter part of backgrounding and only ADG during early part of the finishing period. Generally percent kidney, pelvic, and heart fat was the only adiposity assessment increased (P = 0.003) by dietary oil. The IVGTT results indicated that insulin response to intravenous glucose was lower in Limousin steers than in Wagyu steers. Dietary oil decreased (P = 0.052) fasting plasma insulin concentration in Wagyu steers compared with Limousin steers. The correlation coefficients among the IVGTT measures and intramuscular fat content or marbling score were less than 0.4, and only a negative trend existed between fasting insulin and USDA marbling scores. However, the carcasses of the Wagyu steers graded US Choice, and 66% of the Wagyu carcasses graded US Prime, which were substantially better than the quality grades obtained for the carcasses from the other breed types. Dietary oil did not... [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to compare intercropped barley/annual ryegrass silage (B/RS) and barley silage (BS) on average daily gain (ADG), dry matter intake (DMI) and carcass characteristics of beef steers in a randomized complete block design experiment. Both B/RS and BS were prepared in plastic tube silos, ensiled for 168 days and then used in a feeding trial. Steers (n=120) were housed in individual pens and fed a backgrounding diet containing 350 g steam-rolled barley grain (SBG) and 600 g kg−1 B/RS or 600 g kg−1 BS and 50 g kg−1 supplement until they weighed 445 kg, after which they were adapted to a finishing diet consisting of 860 g SBG and 100 g kg−1 B/RS or 100 g kg−1 BS and 40 g kg−1 supplement. Steer weight and back-fat depth (determined by ultra-sonography) were measured every 3 weeks. Steers were slaughtered when back-fat depth was greater than 7 mm and carcass data were obtained. Content of ADF in B/RS was lower (P<0.05) than in BS, while protein content of the silages was similar. During backgrounding, ADG and DMI of steers fed B/RS (1.43, 8.5 kg per day) were higher (P<0.05) than those fed BS (1.31, 8.0 kg per day) and feed conversion efficiency were similar between two groups of steers. Acetic:propionic ratio of rumen fluid from steers fed either B/RS or BS-based diets in the backgrounding trial were similar. Steers fed B/RS and BS diets had similar ADG, DMI and feed conversion efficiency in the finishing trial. Carcass weights of steers fed B/RS diet were higher (P<0.05) than steers fed BS diet (321.5 kg versus 316.5 kg), but other variables were similar. The total dry matter yield of the intercropped barley/ryegrass was higher (57.6%) than the yield of barley. [Copyright &y& Elsevier]

Abstract: In this investigation in vitro and in vivo trials were performed to determine the efficacy of a cottonseed to limit protozoal population and fermentation parameters. The composition of diets given to the different treatments were as follow: (1) control (without whole cottonseed), 16% crude protein (CP), 3.2% ether extract (E.E.); (2) 20% whole cottonseed, 16% CP, 6.5% E.E.; (3) 20% whole cottonseed, 13% CP, 6.4% E.E. and (4) 20% crushed whole cottonseed, 13% CP, 6.4% E.E. DM disappearance (DMD) and fermentation characteristics of the treatments were determined by in vitro incubation studies. In the in vivo trial, ruminal fluid was taken by rumenocentesis (3h after feeding) on days 1, 3, 5, 7, 9, 11, 14, 21 and 28 from four sheep fed about treatment diets. The pH and protozoal counts were determined in each sample, while ammonia nitrogen and volatile fatty acid (VFA) were determined in samples taken on days 7, 14, 21 and 28. The in vitro DMD after 24h incubation decreased (p <0.01) with the addition of cottonseed in diets 3 and 4 and DMD after 72h incubation was highest (p <0.01) for the control diet. The fractional rate of gas production (c) for the control and diet 2 was higher (p <0.05) than for the diets 3 and 4. Feeding crushed whole cottonseed decreased molar proportion of propionate (p <0.05) and increased molar proportion of butyrate (p <0.01). Low crude protein level increased the molar proportion of propionate (p <0.05) and decreased molar proportion of butyrate (p <0.05) and cellolytic protozoa population (p <0.05). Feeding cottonseed decreased (p <0.05) the total protozoa population from approximately 500,000 to 250,000ml−1 and Holotrich and cellulolytic protozoa disappeared from the rumen of sheep and only Entodinium sp., remained. This was associated with lower concentration of ammonia nitrogen in rumen fluid of sheep fed diets 4 (p <0.05) and 2 (p <0.01). It was concluded that cottonseed reduced rumen fauna and ammonia nitrogen, but had no effect on ruminal VFA while the crushed whole cottonseed decreased molar proportion of isovalerate only. In vivo molar proportion of propionate and butyrate and valerate were increase and decrease, respectively, by decreasing CP percentage in treatment diets. [Copyright &y& Elsevier]

Abstract: As research funding becomes more competitive, it will be imperative for researchers to break the mentality of a single laboratory/single research focus and develop an interdisciplinary research team aimed at addressing real world challenges. Members of this team may be at the same institution, may be found regionally, or may be international. However, all must share the same passion for a topic that is bigger than any individual’s research focus. Moreover, special consideration should be given to the professional development issues of junior faculty participating in interdisciplinary research teams. While participation may be “humbling” at times, the sheer volume of research progress that may be achieved through interdisciplinary collaboration, even in light of a short supply of grant dollars, is remarkable. [Copyright &y& Elsevier]

Abstract: Molecular mechanisms of peroxisome proliferator activated receptors (PPARs) are being defined rapidly, as illustrated by the volume of papers published. Much of the research is directed towards a clinical end-point/application; however, the non-homogeneous nature of adipose depots in laboratory animals is spurring similar research in domestic meat animals (such as beef cattle). Moreover, the size of adipose depots in meat animals remains an attractive feature for using them to obtain cells for PPAR research. Examination of meat-animal depot-specific PPAR moieties may provide novel information about adipocyte regulation that might be extrapolated to all animals. [Copyright &y& Elsevier]