Master of Science / Department of Animal Sciences and Industry / Bradley J. Johnson / Zilpaterol hydrochloride (ZH) is a growth promotant that is approved for use in finishing cattle to improve growth performance and increase lean tissue accumulation. Little is known about the combined effects of ZH with anabolic steroid hormone implants. There is also little published data on the effect these growth promotants have on genes that play a role in skeletal muscle synthesis and degradation. Therefore, two separate studies were conducted to address these issues. The first study evaluated the effects of ZH and the steroid implant Revalor-S (RS) on animal performance and skeletal muscle gene expression in feedlot steers. Four treatments were used to analyze the effects of RS implanted 58 days before ZH, which was fed for 30 days with a 3 day withdrawal. It was determined that ZH and RS additively contribute to improved live and carcass performance; however these compounds had different effects on the abundance of the receptors for ZH as well as the abundance of myosin heavy chain (MHC) mRNA in skeletal muscle of feedlot steers. It was also determined that ZH can cause a transition in the abundance of MHC mRNA isoforms in skeletal muscle that are available for the translation of larger, faster, more glycolytic fiber types of MHC. The second study evaluated the effects of two types of anabolic steroid hormones on myosin heavy chain gene expression. Four treatments were used to measure the effects of trenbolone acetate (TBA) and estradiol (E[subscript]2) on performance and the amount of MHC mRNA in skeletal muscle of finishing steers. It was determined that anabolic steroid implants improve live animal performance, however there was no alteration in the abundance of MHC mRNA in skeletal muscle of feedlot steer for 28 days after implantation; however there was an increase in intermediate fiber type IIA of MHC mRNA in skeletal muscle with increasing days on feed. From these studies we concluded that ZH and anabolic steroids do have an effect on growth performance; however they may differ in the distinct mechanism of action utilized to enhance lean tissue deposition in feedlot steers.

In this study, 14 typical South African feedlot bulls received no beta-adrenergic agonist for the last 30 days of the finishing period (C), 14 received 120 mg R-salbutamol per animal per day for the last 30 days of the finishing period (S30), 13 received 120 mg Rsalbutamol per animal per day for the last 40 days of the finishing period (S40) and the last group of 13 bulls received 60 mg zilpaterol hydrochloride per animal per day for the last 30 days of the finishing period (Zh). All animals were slaughtered after a 3-day withdrawal period. Parameters included weight gain, feed intake, feed conversion rate, warm and cold carcass mass, dressing %, subcutaneous fat thickness, hide yield %, internal carcass fat distribution, % bone, % fat and % muscle of the prime rib-cut, carcass classification code, conformation, compactness, post-mortem carcass pH profiles, cooking loss, shear force, blood urea nitrogen, creatinine and residue levels of the beta-adrenergic agonists. No differences were observed between any of the four treatment groups concerning live feedlot performance. Bulls receiving the S30 and Zh treatments had lower internal carcass fat distribution compared to C bulls (P <0.05). Bulls receiving the S40 treatment had a lower % fat in the prime rib-cut compared to Zh bulls (P <0.05). Carcasses from S30 bulls had higher pH values 24 hours post mortem compared to carcasses from Zh bulls (P <0.01). Meat samples from Zh bulls had higher shear force, which indicates less tender meat, compared to samples from S40 bulls (P <0.05). Change in serum creatinine levels increased only in Zh treated bulls from the start to the end of treatment and may reflect a higher protein turnover in Zh bulls. The results of this study indicate that R-salbutamol has a more pronounced effect on fat metabolism in feedlot bulls compared to zilpaterol hydrochloride, while zilpaterol hydrochloride has a more pronounced effect on protein metabolism. The residue levels in samples of the liver, kidney, muscle and feaces from zilpaterol hydrochloride and R-salbutamol treated bulls were well below acceptable limits. / Dissertation MSc(Agric)--University of Pretoria, 2014 / gm2015 / Animal and Wildlife Sciences / MSc(Agric) / Unrestricted

Master of Science / Department of Animal Sciences and Industry / Michael E. Dikeman / The longissimus lumborum (LL) muscle from 117 steers and the LL, gluteus medius (GM), and triceps brachii (TB) from 132 heifers were obtained to evaluate the effects of feeding zilpaterol hydrochloride (Zilmax®; ZH) (7.56g/907kg on a 100% DM basis) on tenderness. Both genders were blocked by initial weight into 6 blocks of 4 pens. Pens were assigned to treatments of either 0, 20, 30 or 40 d on ZH, with a 3 d withdrawal. One steak was removed from each muscle for proximate analysis and three 2.54 cm thick steaks were vacuum aged for either 7, 14 or 21 d. Steaks were cooked to 70 ˚C and six 1.27 cm diameter cores were removed for Warner-Bratzler shear force (WBSF) determinations. All muscles from steers and heifers fed 30 and 40 d with ZH, had higher (P < 0.05) WBSF compared with controls. The WBSF of steer LL and heifer TB from the 20 d treatment was higher (P < 0.05) than controls. There were no treatment by aging interactions (P > 0.05) for WBSF of steaks from steer LL, heifer LL or heifer TB, but there was a treatment by aging interaction (P < 0.05) for WBSF of steaks from heifer GM. There were no differences (P > 0.05) in percent intramuscular fat for any muscle due to treatment. When using percent intramuscular fat as a covariate, differences in WBSF of steer LL and heifer TB were not altered, but there were slight differences in heifer LL and GM WBSF due to treatment when compared with not using percent fat as a covariate. Percentages of steaks with WBSF ≥ 5 kg increased as days on ZH increased and decreased as days of aging increased. Warner-Bratzler shear force values among the three aging times for steer LL control, 20 and 40 d treatments; all heifer LL treatments, and heifer TB 20 d were all positively correlated (P < 0.01) with each other. Feeding ZH for 20 d generally increased WBSF values, but means were still acceptable. Feeding ZH for 40 d was very detrimental to tenderness.

Orientador: Pedro Eduardo de Felicio / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T15:31:41Z (GMT). No. of bitstreams: 1 PflanzerJunior_SergioBertelli_D.pdf: 1046006 bytes, checksum: 2711bfce1310c3e6cdd951debd20fb7d (MD5) Previous issue date: 2012 / Resumo: Dois estudos foram conduzidos para determinar o efeito da injeção de cloreto de cálcio nas características de palatabilidade e na estabilidade da cor de bifes de coxão mole (M. Semimembranoso) de bovinos suplementados com hidrocloreto de zilpaterol (HZ). No estudo 1 (palatabilidade), 466 bovinos foram divididos em 2 grupos, não-suplementados (n = 233) e suplementados (8,3 mg/kg de HZ nos últimos 20 dias do confinamento; n = 233). Após o abate e resfriamento, 39 carcaças USDA Select foram destinadas aleatoriamente para o teste (não-suplementados = 19; HZ = 20). No estudo 2 (estabilidade da cor), foram utilizados, 20 das 39 carcaças, em igual número de não-suplementados (n = 10) e suplementados HZ (n = 10). Os cortes de coxão mole das duas meias carcaças foram enviados para o laboratório, onde foram destinados alternadamente para os tratamentos não-injetado ou injetado com cloreto de cálcio (5% do peso com solução a 200 mM CaCl2 ). No estudo 1 foram avaliados o comprimento de sarcômero, índice de fragmentação miofibrilar, maciez instrumental (força de cisalhamento por Warner Bratzler - WBSF) e atributos sensoriais dos bifes de coxão mole maturados por até 28 dias. No estudo 2 foram avaliadas a composição centesimal, atividade redutora da metamioglobina (MRA), cor visual e instrumental e oxidação lipídica (TBARS) dos bifes de coxão mole maturados por até 21 dias seguidos da exposição em ¿display¿ por 4 dias. No estudo 1 não houve diferença (P > 0,05) do comprimento de sarcômero entre tratamentos com ou sem HZ. Amostras de animais não suplementados com HZ e amostras injetadas com cloreto de cálcio apresentaram maiores (P < 0,05) índices de fragmentação miofibrilar em relação a suplementados e a não-injetados, respectivamente. A suplementação com HZ não afetou (P > 0,05) as perdas de peso pela exsudação na embalagem, bem como a perda na cocção. A utilização de cloreto de cálcio aumentou (P < 0,05) as perdas de peso. O uso de HZ aumentou (P < 0,05) a WBSF somente dos bi fes maturados por 7 dias. A injeção de cloreto de cálcio em amostras de animais suplementados com HZ anulou (P > 0,05) a diferença na WBSF após 7 dias de maturação e também reduziu (P < 0,05) a WBSF nas amostras dos não suplementados. O HZ não afetou (P > 0,05) as características sensoriais dos bifes maturados por 14 ou 21 dias. Amostras injetadas foram mais macias (P < 0,05) do que as nãoinjetadas, após a maturação por 14 dias, entretanto não houve diferença (P > 0,05) nas maturadas por 21 dias para os atributos sensoriais. Estudo 2: animais tratados com HZ resultaram em carne de cor vermelho-cereja mais claro, maior valor de L * e menores escores de descoloração (P < 0,05). No final da exposição em ¿display¿, os bi fes de animais suplementados com HZ tiveram maiores valores de a * e b * que os controle (P < 0,05). A injeção de CaCl2 resultou em carne de cor vermelha mais intensa e com maiores escores de descoloração (P < 0,05) em amostras maturadas por 14 e 21 dias, mas não influenciou (P > 0,05) a cor aos 7 dias. O valor de L * não foi afetado pela injeção de CaCl2 (P > 0,05). Porém, ao final do período de exposição, as amostras injetadas apresentaram menores valores de a * b * (P < 0,05) que aquelas não-injetadas. A medida que se estendem os períodos de maturação a carne apresentou-se mais escura e com maiores escores de descoloração (P < 0,05). Além disso, a maturação e a exposição continuadas diminuíram (P < 0,05) os valores de a* e b* em ambos os tratamentos de suplementação e injeção. A oxidação lipídica, medida por TBARS, não foi afetada (P > 0,05) pela suplementação com HZ. A injeção de CaCl2 aumentou (P < 0,05) os valores de TBARS. A suplementação dos novilhos com zilpaterol reduziu a maciez das amostras em relação ao grupo não-suplementado. Entretanto a maturação por 14 dias, ou por 7, dias combinada com o tratamento pelo CaCl2 , pode equiparar as médias de maciez objetiva. Na primeira alternativa, o HZ contribuiu para uma maior estabilidade da cor relativamente aos não suplementados, e na segunda, não ocorreu alteração da cor em decorrência do CaCl2 injetado / Abstract: Two studies were conducted to determine the effect of calcium chloride injection on the palatability traits and color stability of steaks from inside round (M. Semimembranosus) of steers supplemented with zilpaterol hydrochloride (ZH). In study 1 (palatability), 466 steers were divided into two groups, non-supplemented and supplemented (8.3 mg/kg of ZH in the last 20 days of feedlot). After slaughter and cooling, 39 USDA Select grade carcasses were randomly destined for the test (non-supplemented = 19; ZH = 20). In study 2 (color stability), 20 from 39 carcasses, previously selected, were randomly destined for the test (non- supplemented = 10, ZH = 10). The inside round of both half-carcasses were sent to the laboratory where they were alternately selected to serve as non-injected or injected with calcium chloride (5 % with 200 mM CaCl2 solution). In study 1 it were evaluated the sarcomere length, myofibrillar fragmentation index, instrumental tenderness (shear force by Warner Bratzler - WBSF) and sensory traits of inside round steaks aged up to 28 days. In study 2 it were evaluated the proximate composition, metmyoglobin reducing activity, visual and instrumental color and lipid oxidation (TBARS) of inside round steaks aged up to 21 days followed by exposure in the display for 4 days. In study 1 there is no difference (P > 0.05) in treatments with or without ZH for sarcomere length. Samples of not ZH supplemented animals and injected samples had higher (P < 0.05) myofibrillar fragmentation index, than supplemented and non-injected, respectively. The ZH supplementation did not affect (P > 0.05) the losses during aging and cooking. The CaCl2 injection increased (P < 0.05) both losses. The use of ZH increased (P > 0.05) WBSF of inside round steaks aged 7 d, however samples aged 14 d did not differ (P > 0.05). The CaCl2 injection in samples from ZH supplemented steers cancelled (P > 0.05) the difference for WBSF after 7 d of aging and reduced (P < 0.05) WBSF in samples from non-supplemented. The ZH did not affect (P > 0.05) sensory traits of steaks aged 14 and 21 d. Injected samples were more tender (P < 0.05) than non-injected after 14 d aging, however there was no difference (P > 0.05) in steaks aged 21 d for sensory traits. In study 2 ZH steaks were lighter cherry red, had higher L* values, and had lower discoloration scores (P < 0.05). At the end of display, ZH steaks had greater (P < 0.05) a* and b* values than non-supplemented. CaCl2 injection resulted in redder beef color, and increased discoloration scores (P < 0.05) in samples aged 14 and 21 d, however it did not affect color traits on d 7 (P > 0.05). L* values were not affected by CaCl2 (P > 0.05), but at the end of display, injected samples had lower a* and b* values than noninjected samples (P < 0.05). Increasing aging and display time resulted in redder color and greater discoloration scores (P < 0.05). Moreover aging and display time decreased (P < 0.05) a* and b* values from both treatments of the two sources of variation. Lipid oxidation, evaluated by TBARS, was not affected by ZH (P > 0.05). The CaCl2 injection increased (P < 0.05) TBARS values. The ZH supplementation decreased tenderness of inside round steaks, however 14 d aging, or 7 d aging combined with CaCl2 injection, can even objective tenderness means, and in the last one, there is no effect in color traits due to CaCl2 injection, as it happens on d 14 and 21 of aging / Doutorado / Tecnologia de Alimentos / Doutor em Tecnologia de Alimentos