Doctor of Philosophy / Department of Animal Sciences and Industry / John M. Gonzalez / American beef producers use a multitude of production regimens, with new products constantly becoming available to producers that could ultimately produce beef that fits niche markets. Additionally, U.S. producers employ the use of two exogenous growth promotants (ExGP), anabolic implants and β-adrenergic agonists, to maximize production efficiency. This body of work examined effects of different production strategies on beef quality. In the first study, steers were fed a conventional diet or a diet containing two supplements of the Programmed Nutrition Beef Program (PN) and each diet was fed with or without ExGP. There were no adverse effects on color, but use of ExGP negatively impacted tenderness of steaks. However, the inclusion of the PN supplements decreased purge loss of loins during aging and decreased cook loss of beef steaks. The decrease in purge and cook loss may be intriguing for retailer who purchase-in and cook products as they could specify a demand for beef from animals in this program to potentially save on product losses. Researchers have examined strategies to increase omega-3 fatty acids within beef, as omega-3 fatty acids are health beneficial. The second study examined impacts of feeding increasing levels of a docosahexaenoic acid (DHA)-rich microalgae to heifers on fatty acid profiles, color stability, and palatability of the LM and color and . Feeding increasing levels of microalgae meal quadratically increased total omega-3 PUFA, with increases in DHA content up to 850% and eicosapentaenoic acid (EPA) up to 340% at the greatest feeding level. Although feeding microalgae changed fatty acid profiles to be more health beneficial, color and flavor were adversely affected. At the end of display, steaks from heifers fed the greatest amount of microalgae had reduced a* (redness) values and increases in surface metmyoglobin (discoloration) formation. Panelists detected more off-flavors as the level of microalgae meal increased in the diet. Poor color stability and increases in off-flavors were due to increased oxidation products in these steaks, but problems could be mitigated by inclusion of antioxidants in the diet. The third study presented examined effects of feeding antioxidants to steers fed microalgae meal on color and palatability of Longissimus lumborum steaks. Steers were fed vitamin E at a level over their nutritional need and a selenium-yeast product in addition to feeding microalgae. Again, feeding microalgae without antioxidants in the diet negatively impacted color during display, but feeding antioxidants significantly improved the color stability. There were no off-flavor differences between steaks from steers fed the diet containing only microalgae and diet containing microalgae with antioxidants. Increasing the antioxidant content of the finishing diet when microalgae was fed is feasible way to increase the color stability of steaks and decrease off-flavors of Longissimus lumborum steaks.

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.

The effects of dietary ingredients on the proteome profile of postmortem beef longissimus lumborum (LL) muscle were evaluated. In the first experiment, the influence of dietary ractopamine on the whole-muscle proteome of beef LL was examined. Five proteins were differentially abundant between ractopamine-fed (RAC) and non-ractopamine fed (CON) groups. The differentially abundant proteins were over-abundant in RAC and were related to muscle structure development (F-actin-capping protein subunit beta-2 and PDZ and LIM domain protein-3), chaperone (heat shock protein beta-1), oxygen transportation (myoglobin), and glycolysis (L-lactate dehydrogenase A chain). These findings indicated that ractopamine influences the abundance of proteins associated with muscle structure and fiber type shift in beef LL. In the second experiment, the effect of Vitamin E supplementation on the sarcoplasmic proteome of beef LL was characterized. Five differentially abundant proteins were observed between vitamin E-supplemented (VITE) and non-vitamin E-supplemented (CONT) groups. All the differentially proteins were over-abundant in CONT and were associated with antioxidant activity (thioredoxin-dependent peroxide reductase, peroxiredoxin-6, and serum albumin) and glycolysis (beta-enolase and triosephosphate isomerase). These results indicated that the strong antioxidant activity of vitamin E leads to low expression of antioxidant proteins and antioxidant-related glycolytic enzymes in beef LL muscle.

Activating the core muscles through exercise training programs is believed to be important for athletic performance. Considerable attention has been credited to the lumbar multifidus, transverse abdominis, and quadratus lumborum in designing exercise training programs. Numerous core exercise claims and recommendations abound in the fitness and physical therapy communities touting a superior core challenge for these muscles. The plethora of core activation literature with conflicting outcomes has convoluted the process of choosing exercises for an optimal core training approach. Although an abundance of research studies have quantified the muscle activity, collectively, a consensus on the type of exercise that elicits the largest muscle activity does not exist. Therefore, the objective of this investigation was to critically examine the literature and synthesize the muscle activity produced across various physical fitness exercises to determine which type of exercise elicits the largest amplitude for the core muscles in healthy individuals. PubMed, EMBASE, SPORTdiscus, CINAHL, (CCRT) and Web of Science databases were searched revealing 27 studies meeting the inclusion criteria measuring EMG activity during 202 exercises. In absence of research for the quadratus lumborum, no conclusions could be made and bring about concern for current recommendations. Furthermore, the methodological diversity significantly limited the quality of studies meriting standardization for future EMG research. Nonetheless, the current evidence suggests free weight exercises and non-core exercises using external resistances produce the largest EMG activity for the lumbar multifidus and transverse abdominis, respectively.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Aimed to verify the effect of maturation of Longissimus thoracic lumborum of Nelore cattle, with four cutting thicknesses (2.5, 5.0, 7.5, and 10 cm) for four periods of maturation (0, 7, 14 and 21 days) on the physical characteristics (pH, color, weight loss for cooking and shearing force); biological (microbiology - mesophilic and psychrotrophic - and sarcomere length); and sensory (softness, odor, flavor and overall acceptance). 64 were used Longissimus thoracic lumborum of Nellore carcasses barrows with 6:08 teeth, acquired Fridge Nutrial, the State of Sergipe. The experimental design was completely randomized, corresponding to a factorial (4x4) with 16 treatments and four replications. Microbiological analysis has revealed the hygiene conditions in which the samples were handled and stored, resulting in psychrophilic counts (2,18x105 UFC/g) and mesophilic (2,4 x105 UFC/g) well below the critical level of impairment (106 UFC/g), indicating the fitness for consumption. For the parameters evaluated in the physical analysis, these were not affected by the thickness of the cuts (P> 0.05). However, different (P <0.05) versus aging time for the red color of the meat (0 = 15.26; 7 = 16,64; 14 = 18,87; 21 = 18.34) and color fat (a * 0 = 9.05, 7 = 7.87, 14 = 13,85; 21 = 12.01 / b * 0 = 14.64; 7 = 13,43; 14 = 12.62 ; 21 = 11.68), shear force (0 = 7.01; 7 = 5.56; 14 = 4.80; 21 = 4.76 kgf) and sarcomere length (0 = 1.49; 7 = 1.67, 14 = 1.62; 21 = 1.58 uM). The pH (5.67), light (45.74), yellow meat content (6.56), and weight loss by cooking (22.35%) did not change as periods of maturation and thicknesses. The Longissimus thoracic lumborum maturation process adult Nelore cattle can be accomplished with any slice thickness and a minimum of 14 days, presenting itself as a quality meat. Sensory analysis has shown that the odor was not significantly different (P> 0.05). The softness of the aged samples showed higher (P <0.05) to non-aged samples did not differ in relation to the thickness of the cut. Regarding flavor and overall acceptance of the product was no difference (P <0.05) between treatments. By means of cluster analysis it was possible to prove the existence of different consumer groups in the most preferred treatments with 21 days of aging, independent of the cutting thickness, and / or the variability of the composition of the groups. Regarding intention to purchase 85% consumers would buy the aged beef for 21 days maturity, regardless of the thickness of the cut. / Objetivou-se verificar o efeito da maturação do Longissimus thoracic lumborum de bovinos Nelores, com quatro espessuras de corte (2,5; 5,0; 7,5; e 10 cm), por quatro períodos de maturação (0; 7; 14 e 21 dias), sobre as características físicas (pH, cor, perda de peso por cocção e força de cisalhamento); biológicas (microbiologia – mesófilos e psicrotróficos – e comprimento de sarcômero); e sensoriais (maciez, odor, sabor e aceitação global). Foram utilizados 64 Longissimus thoracic lumborum de carcaças de bovinos Nelore, machos castrados, com 6 e 8 dentes, adquiridos do Frigorífico Nutrial, do Estado de Sergipe. O delineamento experimental utilizado foi o inteiramente casualizado, correspondendo a um fatorial (4x4) com 16 tratamentos e quatro repetições. A análise microbiológica permitiu revelar as condições higiênicas na qual as amostras foram manuseadas e estocadas, resultando em contagens de psicrotróficos (2,18x105 UFC/g) e mesófilos (2,4 x105 UFC/g) bem abaixo do nível crítico de deterioração (106 UFC/g), indicando a aptidão ao consumo. Para os parâmetros avaliados na análise física, estes não foram influenciados pela espessura dos cortes (P>0,05). Entretanto, diferiram (P<0,05) em função do período de maturação para a intensidade de vermelho da carne (0 = 15,26; 7 = 16,64; 14 = 18,87; 21 = 18,34) e cor da gordura (a*: 0 = 9,05; 7 = 7,87; 14 = 13,85; 21 = 12,01 / b*: 0 = 14,64; 7 = 13,43; 14 = 12,62; 21 = 11,68), força de cisalhamento (0 = 7,01; 7 = 5,56; 14 = 4,80; 21 = 4,76 kgf) e comprimento de sarcômero (0 = 1,49; 7 = 1,67; 14 = 1,62; 21 = 1,58 μm). O pH (5,67), luminosidade (45,74), teor de amarelo da carne (6,56), e perda de peso por cocção (22,35%) não sofreram alteração conforme os períodos de maturação e espessuras. O processo de maturação do Longissimus thoracic lumborum de bovinos Nelore adultos pode ser realizado com qualquer espessura de corte e por um período mínimo de 14 dias, apresentando-se como uma carne de qualidade. A análise sensorial permitiu verificar que o odor não apresentou diferença significativa (P>0,05). A maciez das amostras maturadas apresentou valor superior (P<0,05) às amostras não maturadas, não diferindo em relação à espessura do corte. Para os parâmetros sabor e aceitação global do produto houve diferença (P<0,05) entre os tratamentos. Por meio da análise dos clusters foi possível comprovar a existência de diferentes grupos de consumidores em que a maioria preferiu os tratamentos com maturação de 21 dias, independente da espessura de corte, e/ou da variabilidade da composição dos grupos. Quanto à intenção de compra, 85% consumidores participantes comprariam as carnes maturadas por 21 dias de maturação, independente da espessura do corte.