Master of Science / Animal Sciences and Industry / John M. Gonzalez / Pigs fed ractopamine-HCl (RAC) are more prone to fatigue and exhaustion when improperly handled. Wireless electromyography (EMG) can be used to directly measure median power frequency (MdPF) and root mean square (RMS) as indicators of action potential conduction velocity and muscle fiber recruitment, respectively. The objectives of this study were to determine the effect of RAC on exhaustion, EMG measures, and muscle fiber type characteristics when barrows were subjected to increased levels of activity. Thirty-four barrows were assigned to one of two treatments: a commercial finishing diet containing 0 mg/kg (CON) RAC or a diet formulated to meet the requirements of finishing barrows fed 10 mg/kg RAC (RAC+) for 35 d. After 32 d of feeding, barrows were walked around a circular track at 0.79 m/s until subjective exhausted was reached. Time, distance, and speed were measured. Wireless surface EMG sensors were affixed to the Deltoideus (DT), Triceps brachii lateral head (TLH), Tensor fasciae latae (TFL), and Semitendinosus (ST) muscles. After harvest, samples of each muscle were collected for fiber type, succinate dehydrogenase, and capillary density analysis. Speed was not different (P = 0.82) between treatments, but RAC+ barrows reached subjective exhaustion quicker and covered less distance than CON barrows (P < 0.01). The end-point MdPF was not affected by the RAC diet. The RAC diet did not change end-point RMS values in the DT or TLH; however, the RAC+ barrows tended to have decreased ST and increased TFL end-point RMS values (P < 0.07). The percentage of type I fibers tended to be greater (P = 0.07) in RAC+ barrows, but the RAC diet tended to increase (P = 0.07) size of type I fibers and increase (P = 0.03) the size of type IIA fibers. Succinate dehydrogenase was not different between treatments. The RAC+ barrows had more (P = 0.03) capillaries per fiber than CON barrows. A diet containing RAC contributes to increased onset of subjective exhaustion, possibly due to rapid loss of active muscle fibers and chronic loss of oxidative muscle fibers with no change in muscle metabolism.

Orientador: Pedro Eduardo de Felício / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-24T19:02:58Z (GMT). No. of bitstreams: 1 Joaquim_LeandroOliveira_M.pdf: 827179 bytes, checksum: 88651f4af5cfb6f793546d28ba3e131f (MD5) Previous issue date: 2014 / Mestrado / Tecnologia de Alimentos / Mestre em Tecnologia de Alimentos

Doctor of Philosophy / Department of Animal Sciences and Industry / Twig T. Marston / The primary study investigated the use of ractopamine HCl and implants in cull beef cows. Thirty-two cull cows were used to determine the effects of feeding ractopamine HCl and/or implanting on feedlot performance and carcass composition. Cows were individually fed a high concentrate diet for 60 days. Carcass data were collected and carcasses were fabricated. Implanted cows had greater dressing percentages and tended to have heavier hot carcass weights than non-implanted cows. Cows that had been treated with implant and ractopamine HCl tended to be fatter than those not treated. Ractopamine HCl fed cows had more marbling than their contemporaries. The data also indicated that younger cows (< 6 years of age) had greater feedlot performance than the older cows. An experiment was conducted to determine if corn and grain sorghum dried distillers grains could be effective protein supplements for growing cattle. Crossbred heifers (n = 78) were individually fed 2.72 kg·head·-1d·-1 of supplements containing corn, soybean meal, and grain sorghum; or cracked corn and corn distillers grains with solubles; or cracked corn, sorghum distillers grains with solubles, and ground grain sorghum (all formulated to equal 20% CP). Heifers grazed native-grass and were fed smooth broom hay. A digestion trial was done during the last week of the trial. No differences were noted in weight gain or total diet digestibility, however, DMI was less for heifers receiving either distiller’s based supplement. Ninety-six pregnant, mature, spring-calving cows grazing native grass pasture were used to determine if early weaning calves reduced subsequent winter supplementation cost. Previous to the feeding trial, calves had been weaned at 115 or 212 d of age. Cows were fed either 1.4 kg·hd-1·d-1 or 1.27 kg·hd-1·d-1 of a common 45% CP supplement. Cows were supplemented for an average of 110 d of pregnancy. Earlyweaned cows were heavier and had greater body condition scores than contemporaries at the commencement of supplementation. At calving the early-weaned cows fed the lesser supplemental amount had similar body weight and body condition scores as later-weaned cows fed the greater amount of supplement, thus, the early weaning routine allowed a 30% savings of winter protein supplement.

No description available.

Doctor of Philosophy / Department of Animal Sciences and Industry / Michael D. Tokach / Four experiments were conducted to determine the interactive effects of dietary L-carnitine and ractopamine HCl (ractopamine) on finishing pig growth performance. In analysis of treatments common to all experiments, ractopamine increased (P < 0.01) ADG and G:F compared to pigs not fed ractopamine. Added L-carnitine tended to increase (P < 0.07) ADG and improved (P < 0.01) G:F compared to pigs not fed L-carnitine. Three experiments were conducted to determine the effects of L-carnitine and ractopamine on carcass characteristics and meat quality. In Exp. 1, drip loss decreased (linear, P < 0.04) in pigs fed increasing L-carnitine. In Exp. 2, drip loss decreased (P < 0.04) with increasing L-carnitine when fed with ractopamine. Percentage lean was higher (P < 0.01) for pigs fed ractopamine. In Exp. 3, lean percentage increased (P < 0.03) in pigs fed L-carnitine or ractopamine. Pigs fed L-carnitine tended (P < 0.06) to have decreased drip loss. These results suggest that ractopamine increases carcass leanness and L-carnitine reduces drip loss when fed in combination with ractopamine. Two experiments were conducted to determine the effects of L-carnitine and ractopamine on the metabolic response to handling. Non-gentle handling increased (P < 0.01) lactate and rectal temperature, and decreased pH. In Exp. 1, non-gentle handled pigs fed ractopamine had decreased (P < 0.01) pH and increased temperature and tended (P < 0.09) to have higher lactate than other pigs. In Exp. 2, lactate and temperature changes from immediately post-handling to 1 h post-handling were not different for pigs fed L-carnitine or ractopamine suggesting that L-carnitine did not decrease recovery time of pigs subjected to non-gentle handling or fed ractopamine. These results suggest that pigs fed ractopamine are more susceptible to stress when handled aggressively. Because carnitine did not alleviate the negative effects of handling for pigs fed ractopamine, the improvement in drip loss from feeding carnitine must be due to a different mode of action.

Master of Science / Department of Animal Sciences and Industry / Joel DeRouchey / Mike Tokach / Six experiments using 3,862 pigs were conducted to evaluate effects of ractopamine HCl (RAC) feeding programs, dietary L-Carnitine and dried distillers grains with solubles (DDGS) on growth, carcass traits, loin and jowl fat quality of pigs, and energy and protein sources in nursery diets. In Exp. 1 and 2, RAC-fed pigs had greater (P<0.05) ADG, G:F and HCW compared with the control. Within RAC treatments, there were no differences in growth. Pigs fed step-up RAC had increased (P<0.01) percentage lean, fat-free lean index and loin depth but decreased (P<0.01) backfat than the control or constant treatment. In Exp. 2, pigs fed step-up RAC program had greater (P<0.05) ADG and G:F than the constant treatment. Pigs fed constant RAC had greater (P=0.002) carcass yield than controls. There were no overall differences in other carcass traits among treatments. In Exp. 3, dietary L-Carnitine improved (P<0.02) ADG and final BW. A DDGS × L-Carnitine interaction (quadratic, P<0.01) was observed for G:F. Pigs not fed DDGS had similar G:F, but in DDGS diets pigs fed 50 ppm L-Carnitine had worse G:F than those fed 100 ppm. Pigs fed L-Carnitine had greater (P<0.02) HCW compared with those not fed L-Carnitine. Increasing L-Carnitine up to 100 ppm increased HCW (quadratic, P<0.03) and backfat (quadratic, P<0.04), with the maximum response at 50 ppm dietary L-Carnitine. Increasing L-Carnitine increased (linear, P<0.04) purge loss of loin. Feeding DDGS increased (P<0.001) linoleic acid and iodine value of jowl fat compared with feeding no DDGS. However, feeding L-Carnitine did not change jowl fatty acid composition. In Exp. 4, 5 and 6, nursery pigs fed choice white grease (CWG) had improved (P<0.02) G:F than pigs fed a control diet or an alcohol based energy source. Also, pigs fed CWG had greater (P<0.04) ADG in Exp. 4 and 6 and had reduced (P<0.01) ADFI in Exp. 5. The alcohol based energy source improved (P<0.04) ADG and ADFI with no change in G:F in Exp. 4; but did not affect growth in Exp. 5 and 6. In Exp. 6, pigs fed AV-E Digest had equal performance as nursery pigs fed other specialty proteins.

Este estudo teve como objetivo avaliar o efeito do uso de dois beta-agonistas adrenérgicos (&beta;AA), cloridrato de zilpaterol (ZIL) e cloridrato de ractopamina (RAC), em combinação com a técnica de imunocastração sobre o desempenho, perfil sanguíneo, comportamento ingestivo e características de carcaça de bovinos confinados na fase de terminação. Noventa e seis bovinos machos da raça Nelore, com peso vivo inicial médio de 409 kg &plusmn; 50 kg e idade média de 20 meses, foram divididos em dois grupos de 48 animais, no qual metade dos animais de cada grupo recebeu a vacina de imunocastração enquanto que a outra metade não recebeu a vacina. Os animais foram alimentados por 70 dias com uma dieta comum contendo 76% de concentrado e 24% de volumoso (silagem de milho). Após 70 dias de confinamento, os animais foram divididos em três grupos, de acordo com o peso, dentro de cada bloco e condição sexual, e aleatoriamente alimentados com uma das seguintes dietas, pelos 30 dias seguintes: CON - dieta padrão utilizada na fase anterior, sem a adição de &beta;AA; ZIL - dieta padrão acrescida de 80 mg/dia cloridrato de zilpaterol; RAC - dieta padrão acrescida de 300 mg/dia cloridrato de ractopamina. Foi avaliado o desempenho, área de olho de lombo (AOL), espessura de gordura subcutânea (EGS) e espessura de gordura na picanha (EGP), bem como o comportamento ingestivo e a gasometria e o perfil bioquímico sanguíneo. No abate foi avaliado o peso vivo final (PVF), peso de carcaça quente (PCQ) e rendimento de carcaça quente (RCQ). Não houve interação entre os fatores principais para nenhuma característica avaliada. Os animais não-castrados tiveram maior ganho médio diário (GMD) e eficiência alimentar (EA) quando comparado aos animais imunocastrados, além de apresentarem maior PCQ e AOL, porém, sem alterar o RCQ, e menor EGS e EGP do que animais imunocastrados. Animais imunocastrados tiveram maior concentração sérica nas principais variáveis relacionadas ao metabolismo e deposição de gordura, tais como HDL, triglicerídeo, colesterol e ácido graxo não-esterificado. Não houve efeito dos tratamentos nem da condição sexual sobre o comportamento ingestivo dos animais. Os animais suplementados com ZIL foram superiores no GMD, EA, AOL, RCQ, porém, sem alterar o PCQ, e inferiores na EGS e EGP quando comparados a animais CON e RAC. Animais suplementados com ZIL apresentaram concentrações séricas representativas de maior metabolismo e deposição de proteína, tais como menores taxas de ureia e maiores taxas de creatino quinase. Não houve efeito da RAC sobre o CON em nenhuma das características supracitadas. A imunocastração diminui a deposição muscular e aumenta a deposição de gordura na carcaça, enquanto que os &beta;AA aumentam a proporção muscular e diminuem a proporção de gordura, havendo impacto direto no desempenho e nas características e rendimento de carcaça, sem haver interação dessas tecnologias nas características avaliadas, portanto, ambas devem ser avaliadas separadamente. / This study aimed to evaluate the effect of two beta-adrenergic agonists (&beta;AA), zilpaterol hydrochloride (ZH) and ractopamine hydrochloride (RH), in combination with immunocastrion technique on performance, blood profile, feeding behavior, and carcass traits of Nellore cattle in feedlot finishing phase. Ninety-six males Nellore cattle (409 &plusmn; 50 kg LW; 20 mo old) were divided in two groups with forty-eight animals and half of them each group received immunocastration vaccine. Animals were fed for 70 days a common diet containing 76% concentrate and 24% roughage (corn silage). Following they were split in 3 groups, according to weight and within block and sex condition, and fed 30 more days one of the following treatments: CON - basis diet without &beta;AA; ZH - basis diet plus 80mg/d zilpaterol hydrochloride; RH - basis diet plus 300mg/d of ractopamine hydrochloride. Performance, loin muscle area (LMA), backfat thickness (BFT), rump fat thickness (RFT), feeding behavior, gas blood, and blood biochemical profile were recorded in the feedlot. Final liveweight (FLW), hot carcass weight (HCW) and dressing percent (DP) were recorded in the harvest. There was no interaction between the main factors for any traits evaluated. Non-castrated animals had higher average daily gain (ADG) and feed efficiency (G:F) compared to immunocastrated animals, besides higher HCW and LMA, however, without changing DP, and lower BFT and RFT than immunocastrated animals. Immunocastrated animals showed greater serum concentration in the main variables associated to metabolism and fat deposition, such as HDL, triglycerides, cholesterol, and non-esterified fatty acid. No effect of treatments or sex condition on feeding behavior. The animals supplemented with ZH were higher in ADG, G:F, LMA, DP, however, without altering the HCW, and lower in BFT and RFT compared to CON and RH animals. ZH animals showed serum concentration representative of greater metabolism and muscle deposition, such as lower urea rates and higher creatinekinase levels. There was no effect of RH on the CON in any traits abovementioned. Immunocastration decreases the muscle deposition and increases the fat deposition in the carcass, whereas the &beta;AA increases the muscle proportion and decreases the fat proportion, which has effect on performance, carcass traits and dressing percent, with no interaction of these technologies in the characteristics evaluated, thereby both should be evaluated separately.

A ractopamina (Rac) tem sido utilizada durante a gestação de fêmeas suínas gestantes, com objetivo de melhorar o aporte nutricional ao feto, sendo considerada como repartidor de nutrientes, promovendo a lipólise e a retenção de nitrogênio, e a síntese proteica. O aumento no fluxo de nutrientes pode apresentar impactos positivos na condição corporal da fêmea gestante e o desenvolvimento do feto. O presente trabalho avaliou os efeitos da inclusão de 10 e 20 mg/kg de ractopamina na ração de fêmeas suínas gestantes, entre os dias 25 a 50 da gestação, sobre o desempenho produtivo, reprodutivo, parâmetros fisiológicos, hemograma e bioquímica sanguínea das fêmeas e sobre a vitalidade, hemograma, bioquímica sanguínea, número de fibras musculares no músculo semitendinosus e estado metabólico dos leitões. Foram utilizadas 41 fêmeas de linhagem comercial híbrida, DB 90 (DB-Genética Suína, Patos de Minas, MG), divididas de acordo com a ordem de parto em 3 tratamentos: Controle: sem ractopamina; Rac10: 10 mg/kg de ractopamina; Rac20: 20 mg/kg de ractopamina. O tratamento foi administrado diariamente via top dressed durante os 25 a 50 dias de gestação. As avaliações e as coletas de amostras foram realizadas nos 25, 37, 50, 107 dias de gestação e nos 1, 7, 14 e 21 dias da lactação. Para a avaliação da vitalidade foi utilizado o teste de pontuação Apgar modificado por Motta-Rojas (2005). A suplementação de ractopamina durante a gestação não influenciou o desempenho reprodutivo das fêmeas, dos leitões até o desmame e no número de fibras musculares no músculo semitendinosus ao nascimento. Houve um aumento na frequência cardíaca e de leitões com vitalidade baixa nas fêmeas suplementadas com Rac. Houve alterações no hemograma, bioquímica sanguínea das fêmeas, mas não nos leitões. Os resultados obtidos a partir das análises do hemograma e bioquímica sanguínea indicam ação da ractopamina sobre o metabolismo lipídico e proteico das fêmeas sem reflexos importantes nos valores observados nos leitões. O presente trabalho concluiu que a suplementação de Rac durante os 25 a 50 dias da gestação não influencia negativamente no metabolismo das fêmeas e sua progênie até o desmame. Por outro lado, a suplementação de Rac aumenta a frequência cardíaca sem aumento de frequência respiratória e temperatura retal das fêmeas, no entanto, pode ser considerado ainda dentro dos parâmetros fisiológicos normais durante a gestação. O aumento no número de leitões de vitalidade baixa 10 pode estar relacionado a um aumento numérico do peso ao nascimento dos leitões. Contudo, a suplementação de Rac durante os 25 50 dias da gestação não influencia negativamente no desempenho produtivo das fêmeas e sua progênie até o desmame. / The ractopamine (Rac) has been used in pregnant sows, aiming to improve the nutritional contribution to the fetus, being considered as nutrient delivery, promoting lipolysis and retention of nitrogen and protein synthesis. Increased nutrient flow may have positive impacts on the body condition of sows and fetal development. The present study evaluated the effects of the inclusion of 10 and 20 mg / kg of ractopamine in the diet sows from 25 to 50 days of pregnancy. Assessing possible effects on productive, reproductive performance, physiological parameters, complete blood count and blood serum biochemistry of females and on vitality, complete blood count, blood serum biochemistry, number of muscle fibers in the semitendinosus muscle and metabolic status of their piglets. Forty one sows of hybrid commercial line, DB 90 (DB-Genetics Swine, Patos de Minas, Minas Gerais),were used and divided according to the order of parity in 3 treatments: Control: No ractopamine; Rac10: 10 mg / kg ractopamine; Rac20: 20 mg / kg ractopamine. The treatment was administered daily via top dressed during the 25 to 50 days of gestation. The evaluations and sample collections were performed at 25, 37, 50, 107 days of gestation and at 1, 7, 14 and 21 days of lactation. Assessment of vitality was used the apgar score test modified by Motta-Rojas (2005). The supplementation of ractopamine during gestation did not influence the female reproductive performance, piglets performance until weaning and muscle fibers in the semitendinosus muscle at birth. There was an increase in heart rate and low vitality in females supplemented with Rac. There were alterations in the complete blood count, blood serum biochemistry of the females, but not in the piglets. The results obtained from the hemogram and blood biochemistry analysis indicate the action of ractopamine on the lipid and protein metabolism of the females without significant reflexes in the piglets values. The present study concluded that the supplementation of Rac during the 25 to 50 days of gestation does not negatively influence the metabolism of the females and their progeny until weaning. On the other hand, supplementation of Rac increases the heart rate without increasing respiratory rate and rectal temperature of the females, however, this can still be considered within the normal physiological parameters during gestation. The increase in the numbers of low-vitality piglets may be related to a numerical increase in the birth weight of the piglets. However, Rac 12 supplementation during the 25-50 days of gestation does not negatively influence the productive performance of the females and their progeny until weaning.

A ractopamina (Rac) tem sido utilizada durante a gestação de fêmeas suínas gestantes, com objetivo de melhorar o aporte nutricional ao feto, sendo considerada como repartidor de nutrientes, promovendo a lipólise e a retenção de nitrogênio, e a síntese proteica. O aumento no fluxo de nutrientes pode apresentar impactos positivos na condição corporal da fêmea gestante e o desenvolvimento do feto. O presente trabalho avaliou os efeitos da inclusão de 10 e 20 mg/kg de ractopamina na ração de fêmeas suínas gestantes, entre os dias 25 a 50 da gestação, sobre o desempenho produtivo, reprodutivo, parâmetros fisiológicos, hemograma e bioquímica sanguínea das fêmeas e sobre a vitalidade, hemograma, bioquímica sanguínea, número de fibras musculares no músculo semitendinosus e estado metabólico dos leitões. Foram utilizadas 41 fêmeas de linhagem comercial híbrida, DB 90 (DB-Genética Suína, Patos de Minas, MG), divididas de acordo com a ordem de parto em 3 tratamentos: Controle: sem ractopamina; Rac10: 10 mg/kg de ractopamina; Rac20: 20 mg/kg de ractopamina. O tratamento foi administrado diariamente via top dressed durante os 25 a 50 dias de gestação. As avaliações e as coletas de amostras foram realizadas nos 25, 37, 50, 107 dias de gestação e nos 1, 7, 14 e 21 dias da lactação. Para a avaliação da vitalidade foi utilizado o teste de pontuação Apgar modificado por Motta-Rojas (2005). A suplementação de ractopamina durante a gestação não influenciou o desempenho reprodutivo das fêmeas, dos leitões até o desmame e no número de fibras musculares no músculo semitendinosus ao nascimento. Houve um aumento na frequência cardíaca e de leitões com vitalidade baixa nas fêmeas suplementadas com Rac. Houve alterações no hemograma, bioquímica sanguínea das fêmeas, mas não nos leitões. Os resultados obtidos a partir das análises do hemograma e bioquímica sanguínea indicam ação da ractopamina sobre o metabolismo lipídico e proteico das fêmeas sem reflexos importantes nos valores observados nos leitões. O presente trabalho concluiu que a suplementação de Rac durante os 25 a 50 dias da gestação não influencia negativamente no metabolismo das fêmeas e sua progênie até o desmame. Por outro lado, a suplementação de Rac aumenta a frequência cardíaca sem aumento de frequência respiratória e temperatura retal das fêmeas, no entanto, pode ser considerado ainda dentro dos parâmetros fisiológicos normais durante a gestação. O aumento no número de leitões de vitalidade baixa 10 pode estar relacionado a um aumento numérico do peso ao nascimento dos leitões. Contudo, a suplementação de Rac durante os 25 50 dias da gestação não influencia negativamente no desempenho produtivo das fêmeas e sua progênie até o desmame. / The ractopamine (Rac) has been used in pregnant sows, aiming to improve the nutritional contribution to the fetus, being considered as nutrient delivery, promoting lipolysis and retention of nitrogen and protein synthesis. Increased nutrient flow may have positive impacts on the body condition of sows and fetal development. The present study evaluated the effects of the inclusion of 10 and 20 mg / kg of ractopamine in the diet sows from 25 to 50 days of pregnancy. Assessing possible effects on productive, reproductive performance, physiological parameters, complete blood count and blood serum biochemistry of females and on vitality, complete blood count, blood serum biochemistry, number of muscle fibers in the semitendinosus muscle and metabolic status of their piglets. Forty one sows of hybrid commercial line, DB 90 (DB-Genetics Swine, Patos de Minas, Minas Gerais),were used and divided according to the order of parity in 3 treatments: Control: No ractopamine; Rac10: 10 mg / kg ractopamine; Rac20: 20 mg / kg ractopamine. The treatment was administered daily via top dressed during the 25 to 50 days of gestation. The evaluations and sample collections were performed at 25, 37, 50, 107 days of gestation and at 1, 7, 14 and 21 days of lactation. Assessment of vitality was used the apgar score test modified by Motta-Rojas (2005). The supplementation of ractopamine during gestation did not influence the female reproductive performance, piglets performance until weaning and muscle fibers in the semitendinosus muscle at birth. There was an increase in heart rate and low vitality in females supplemented with Rac. There were alterations in the complete blood count, blood serum biochemistry of the females, but not in the piglets. The results obtained from the hemogram and blood biochemistry analysis indicate the action of ractopamine on the lipid and protein metabolism of the females without significant reflexes in the piglets values. The present study concluded that the supplementation of Rac during the 25 to 50 days of gestation does not negatively influence the metabolism of the females and their progeny until weaning. On the other hand, supplementation of Rac increases the heart rate without increasing respiratory rate and rectal temperature of the females, however, this can still be considered within the normal physiological parameters during gestation. The increase in the numbers of low-vitality piglets may be related to a numerical increase in the birth weight of the piglets. However, Rac 12 supplementation during the 25-50 days of gestation does not negatively influence the productive performance of the females and their progeny until weaning.

A high moisture corn/soybean meal-based finishing ration was used to examine the effects of roughage source (corn silage, alfalfa hay), level of dietary roughage (8, 16, 24%), and ractopamine supplementation (none, Optaflexx) on growth performance, carcass traits, and beef quality for finishing 108 steers and 24 heifers (initial BW = 308 kg). Cattle were allocated by gender to 12 management regimen subclasses. Optaflexx (trade name for ractopamine hydrochloride) was fed over the last 28 d on feed with cattle marketed after common days on feed. Growth performance (ADG, feed intake, and feed efficiency) and carcass traits were assessed on an individual animal basis. A primal rib and semitendinosus (ST) muscle from each animal were processed at the University of Guelph Meat Laboratory for carcass and meat quality evaluations. Tenderness was determined using shear force assessment of product aged 7, 14, and 21 d. Average daily gains were similar (P > 0.27) across main effects while use of corn silage as the roughage source decreased (P < 0.001) dry matter intake and improved (P < 0.001) feed efficiency compared to feeding alfalfa hay. Roughage level and beta agonist supplementation did not affect (P > 0.13) dry matter intake or feed efficiency. When the last 28 days on feed were examined, Optaflexx supplementation increased (P < 0.001) weight change, ADG, and improved feed conversion, while DMI remained unchanged (P > 0.373). Carcass traits including hot carcass weight, grade fat, longissimus muscle area, marbling, and body composition as assessed by rib dissection (% lean, fat, bone) were not affected (P > 0.14) by roughage level, source, or use of Optaflexx. Fat partitioning and liver abscess scores were unaffected (P > 0.09) by source and level of roughage fed, and use of Optaflexx. Source and level of dietary roughage did not affect color (P > 0.21) or shear force (P > 0.20) values for longissimus (LM) and semitendinosus (ST) steaks. Lower DMI and better feed conversion can be achieved using corn silage as the roughage source, while inclusion of up to 24% roughage in finishing diets may not negatively impact gains, carcass characteristics or beef quality. Beef producers may be able to increase amounts of roughage in the diet to lower cost of production without compromising growth performance and carcass and meat quality.