Master of Science / Department of Animal Sciences and Industry / Dale A. Blasi / An experiment was conducted to evaluate the effects of dry matter intake (DMI) restriction on early receiving performance by steers in a drylot and subsequent grazing performance, feedlot performance, and carcass characteristics. During the backgrounding period, crossbred, weanling steers (n = 329; initial BW = 191± 5.52 kg ) were randomly assigned to 1 of 4 DMI levels corresponding to ad libitum, 2.50% of BW (2.50%), 2.25% of BW (2.25%), and 2.00% of BW (2.00%) for 62 d. During the subsequent grazing period, the same steers were randomly assigned to 13 paddocks to graze for 90 d. Paddocks were stocked at 281 kg live weight per hectare. Initial steer BW were similar on each pasture and each backgrounding treatment was equally represented within a paddock. During the feedlot period, steers were finished at a commercial feedlot and were assigned to 1 of 4 pens according to their rank in BW. Entire pens were harvested when average steer BW reached 545 kg. During the backgrounding period, ad libitum-fed steers had greater (P < 0.001) ADG and final BW than other treatments; steers fed at 2.50 and 2.25% of BW had similar ADG and final BW and were greater (P < 0.001) than steers fed 2.00% of BW. During the grazing period, compensatory gain was observed in restricted DMI treatments. Steers fed at 2.00% of BW had greater (P = 0.006) ADG than ad libitum-fed steers but an ADG similar to that of the other restricted DMI treatments. Steers fed ad libitum, 2.50% of BW, and 2.25% of BW had similar final BW and steers fed 2.00% of BW had lesser (P < 0.001) final BW than other treatments. During the feedlot phase, steers fed 2.00% of BW were on feed longer (P < 0.05) than other treatments. Growth compensation during grazing illustrated that restricted feeding immediately prior to pasture grazing can reduce backgrounding costs.

A 2-year grazing study was conducted to evaluate the growth performance, ruminal fermentation, carcass characteristics, and fatty acid compositions in subcutaneous adipose tissue of beef steers grazing tall fescue (Festuca arundinacea Shreb.; TF) pastures without or with N fertilization. Nitrogen fertilization increased crude protein concentration of TF pasture and average daily gain of beef steers. Increase in total volatile fatty acids (VFA) and ammonia-N (NH3-N) concentrations were detected in steers grazing fertilized TF. In comparison with steers on feedlot, pasture-finished steers had greater proportions of cis-9, trans-11 CLA and C18:3 n-3, but lower n-6:n-3 ratio in adipose tissue. In the first in vitro study using 2 energy supplements [corn or dried distillers grains with solubles (DDGS)] and 4 pasture mixture forages [TF without or with N fertilizer (TF˗NF or TF+NF), TF-alfalfa mixture (TF+AF), and TF-birdsfoot trefoil mixture (TF+BT)], we found that corn supplementation increased total VFA and propionate concentrations, while DDGS supplementation decreased total VFA concentrations. Lower NH3-N concentration and methane (CH4) production were observed due to energy supplementation, in particular when corn grain was supplemented. Similar NH3-N:VFA ratios were detected in the cultures fed the TF+NF and the TF+BT. This result indicates that the TF+BT had similar fermentation efficiency on in vitro ruminal metabolism compared with the TF+NF. The second in vitro study was performed to investigate the effects of grass-to-legume ratios of 3 different TF-legume mixed diets on in vitro fermentation characteristics in continuous cultures. Propionate concentration increased with the increasing of legume proportion in the mixed diets. The greatest propionate concentration was shown by cultures fed the TF+CM, while the TF+AF and the TF+BT maintained a similar propionate concentration. Increasing legume proportion in the forage diets also increased NH3-N concentration, but decreased CH4 production in the cultures. Further decrease of CH4 production was recorded when the TF+BT was fed to the cultures. Overall results from the grazing study demonstrate that N fertilizer can improve nutrient quality of TF as well as growth performance of grazing steers, while the in vitro studies showed positive effects of grass-legume mixture diets on in vitro microbial metabolism by improving ruminal fermentation and reducing CH4 production.

Forty-five Angus steers (358 kg BW) were utilized in a completely randomized block design with a 3 x 3 factorial arrangement of treatments to evaluate the hypothesis that differing dietary linolenic acid (from corn, flaxseed plus corn, or milo) and whole cottonseed (WCS) inclusion (0, 5, or 15% DM) would interact to alter fatty acid metabolism and deposition of conjugated linoleic acid (CLA) in subcutaneous (s.c.) and interfasicular (i.f.) adipose tissues, and thereby decrease carcass quality score. During the feeding period (135 d), steers receiving flaxseed or corn diets had a greater gain:feed ratio (0.119 and 0.108, respectively) than steers receiving the milo diet (0.093). Following transportation to a local abattoir and overnight starvation, there was less decrease in weight in flaxseed-fed steers (1.51%) than in steers fed the corn (2.89%) or milo diets (3.11%). Ribeye area of steers fed milo was less than that of steers fed the corn or flaxseed diets. Lipogenesis from acetate in s.c. adipose tissue was greater in steers fed flaxseed (5.42 nmol h-1 105 cells-1) than in the corn (3.10 nmol h-1 105 cells-1) or milo (1.92 nmol h-1 105 cells-1) groups. Stearoyl-CoA desaturase (SCD) activity in s.c. adipose tissue was unchanged between the 0% WCS group (88.1 nmol mg protein-1 7 min-1) and the 15% WCS group (20 nmol mg protein-1 7 min-1). The i.f. saturated fatty acid percentages increased with increasing levels of WCS. The i.f. cis-9, trans-11 CLA percentage increased with increasing WCS in the steers fed the corn diet, whereas it remained unchanged or even decreased slightly in the steers fed the flaxseed or milo-based diets. Steers fed flaxseed had a greater s.c. adipose concentration of vaccenic acid (18:1trans-11) than the steers fed milo. Steers fed flaxseed also had greater s.c. and i.f. percentages of linolenic acid (18:3, n-3) than steers fed either of the other grain sources. Increased dietary linolenic acid from flaxseed may have increased s.c. adipocyte volume by stimulating lipogenesis. These data indicate that rations formulated to provide increased levels of linolenic acid (i.e., flaxseed) will increase feed efficiency and lipogenesis from acetate without altering either the quality or composition of the beef carcasses.

There is a growing interest in documenting the effect of diet on the ability to convert saturated fatty acids (SFA) to monounsaturated fatty acids (MUFA) by modulating expression of the SCD gene. We propose that if cattle were raised to a constant body weight, their MUFA:SFA ratio will be the same regardless of being calf-fed (CF) or yearling-fed (YF). Twenty-four Angus cattle were acquired for this study. Cattle were slaughtered at weaning at 8 mo of age (SFCF, n=4), eight steers were assigned to the CF group and slaughtered at 12 mo of age (MFCF, n=4) and 16 mo of age (LFCF, n=4). Twelve cattle were assigned to the YF group and slaughtered at 12 mo of age (SFYF, n=4) 16 mo of age (MFYF, n=4) and market weight of 525 kg (LFYF, n=4). Cattle were then statistically analyzed based on time on high energy diet. Fatty acids from digesta, plasma, liver, L. dorsi, and s.c. and i.m. adipose tissue were all analyzed by FAME. In s.c. 18:1 and 16:1 were greatest in LFCF (41.27% and 5.58%, respectively, P = 0.05), and 18:0 and 16:0 did not differ between groups (P > 0.10). MUFA:SFA ratios of s.c. tended to be higher in LFCF animals (1.26) vs. LFYF (1.06, P = 0.10). However, there was no difference seen when comparing CF to YF animals (P = 0.26). MUFA:SFA ratio was higher in i.m. (P = 0.03) and also increased with age (P < .01). A trained sensory panel saw no significant differences between palatability of flavor characteristics of cooked steaks from LFCF, MFYF, or LFYF (P > 0.05). We showed increased SCD gene expression in the LFYF (248.41 to 1528.69 SCD/GAPDH, P = 0.01). Expression was higher in YF (P = 0.04), but their initial deposits of SFA, combined with the lack of SCD expression while on pastures, prevented the MUFA:SFA ratio from increasing at a rate fast enough to change the final ratios in the animal.

There is a growing interest in documenting the effect of diet on the ability to convert saturated fatty acids (SFA) to monounsaturated fatty acids (MUFA) by modulating expression of the SCD gene. We propose that if cattle were raised to a constant body weight, their MUFA:SFA ratio will be the same regardless of being calf-fed (CF) or yearling-fed (YF). Twenty-four Angus cattle were acquired for this study. Cattle were slaughtered at weaning at 8 mo of age (SFCF, n=4), eight steers were assigned to the CF group and slaughtered at 12 mo of age (MFCF, n=4) and 16 mo of age (LFCF, n=4). Twelve cattle were assigned to the YF group and slaughtered at 12 mo of age (SFYF, n=4) 16 mo of age (MFYF, n=4) and market weight of 525 kg (LFYF, n=4). Cattle were then statistically analyzed based on time on high energy diet. Fatty acids from digesta, plasma, liver, L. dorsi, and s.c. and i.m. adipose tissue were all analyzed by FAME. In s.c. 18:1 and 16:1 were greatest in LFCF (41.27% and 5.58%, respectively, P = 0.05), and 18:0 and 16:0 did not differ between groups (P > 0.10). MUFA:SFA ratios of s.c. tended to be higher in LFCF animals (1.26) vs. LFYF (1.06, P = 0.10). However, there was no difference seen when comparing CF to YF animals (P = 0.26). MUFA:SFA ratio was higher in i.m. (P = 0.03) and also increased with age (P < .01). A trained sensory panel saw no significant differences between palatability of flavor characteristics of cooked steaks from LFCF, MFYF, or LFYF (P > 0.05). We showed increased SCD gene expression in the LFYF (248.41 to 1528.69 SCD/GAPDH, P = 0.01). Expression was higher in YF (P = 0.04), but their initial deposits of SFA, combined with the lack of SCD expression while on pastures, prevented the MUFA:SFA ratio from increasing at a rate fast enough to change the final ratios in the animal.

Forty-five Angus steers (358 kg BW) were utilized in a completely randomized block design with a 3 x 3 factorial arrangement of treatments to evaluate the hypothesis that differing dietary linolenic acid (from corn, flaxseed plus corn, or milo) and whole cottonseed (WCS) inclusion (0, 5, or 15% DM) would interact to alter fatty acid metabolism and deposition of conjugated linoleic acid (CLA) in subcutaneous (s.c.) and interfasicular (i.f.) adipose tissues, and thereby decrease carcass quality score. During the feeding period (135 d), steers receiving flaxseed or corn diets had a greater gain:feed ratio (0.119 and 0.108, respectively) than steers receiving the milo diet (0.093). Following transportation to a local abattoir and overnight starvation, there was less decrease in weight in flaxseed-fed steers (1.51%) than in steers fed the corn (2.89%) or milo diets (3.11%). Ribeye area of steers fed milo was less than that of steers fed the corn or flaxseed diets. Lipogenesis from acetate in s.c. adipose tissue was greater in steers fed flaxseed (5.42 nmol h-1 105 cells-1) than in the corn (3.10 nmol h-1 105 cells-1) or milo (1.92 nmol h-1 105 cells-1) groups. Stearoyl-CoA desaturase (SCD) activity in s.c. adipose tissue was unchanged between the 0% WCS group (88.1 nmol mg protein-1 7 min-1) and the 15% WCS group (20 nmol mg protein-1 7 min-1). The i.f. saturated fatty acid percentages increased with increasing levels of WCS. The i.f. cis-9, trans-11 CLA percentage increased with increasing WCS in the steers fed the corn diet, whereas it remained unchanged or even decreased slightly in the steers fed the flaxseed or milo-based diets. Steers fed flaxseed had a greater s.c. adipose concentration of vaccenic acid (18:1trans-11) than the steers fed milo. Steers fed flaxseed also had greater s.c. and i.f. percentages of linolenic acid (18:3, n-3) than steers fed either of the other grain sources. Increased dietary linolenic acid from flaxseed may have increased s.c. adipocyte volume by stimulating lipogenesis. These data indicate that rations formulated to provide increased levels of linolenic acid (i.e., flaxseed) will increase feed efficiency and lipogenesis from acetate without altering either the quality or composition of the beef carcasses.

Submitted by (edna.saturno@ufrpe.br) on 2017-04-24T14:48:26Z No. of bitstreams: 1 Jose Ricardo Coelho da Silva.pdf: 365366 bytes, checksum: 9b5766c3b86e5a0cb19a9c18eb75018d (MD5) / Made available in DSpace on 2017-04-24T14:48:26Z (GMT). No. of bitstreams: 1 Jose Ricardo Coelho da Silva.pdf: 365366 bytes, checksum: 9b5766c3b86e5a0cb19a9c18eb75018d (MD5) Previous issue date: 2011-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of this issue was to evaluate the quantitative and qualitative characteristics of the carcass of dairy steers receiving diets based on spineless cactus and sorghum silage; the silage is associated by cottonseed meal, and the use of ultrasound to evaluate carcass of Holstein-Zebu young cattle destined for slaughter. The study was conducted at the Experimental Station of Caruaru, belonging to the Agronomic Institute of Pernambuco - IPA, located in the city of Caruaru, Pernambuco. It was used 18 non castrated steers, 5/8 Holstein-Zebu breed, with an average initial weight of 320 kg and 24 months old, approximately. The animals were confined for 84 days, divided into three periods of 28 days, housed in individual pens equipped with feeders and drinkers. To obtain ultrasound images it was used an Esaote Europe Aquila Vet equipment, with the transducer of 18 cm in length, coupled with acoustic guide to better fit the anatomy of the animal and frequency of 3.5 MHz. Ultrasound measurements were taken from loin eye area (LEA-US), subcutaneous fat thickness (SFT-US) and rump fat thickness (RFT-US), which were correlated with the weights of the front and back, and the yield of the back. Were also performed correlations between measures of LEA and SFT measured by ultrasound in the carcass. After slaughter, it was recorded the hot carcass weight, the weight of the haunches, the length of carcass, leg and thigh. The meat quality was assessed by the ultimate pH, color, cooking loss, the water holding capacity and shear force. It was performed the estimation of carcass composition by separating the tissues that make up the section between the 9th and 11th ribs (HH section). The effects of experimental diets did not differ, showing that spineless cactus associated with silage and urea produced meat qualitative characteristic and quantitative carcass of Holstein-Zebu young cattle similar to the diets supplemented with cottonseed meal, except the back weight, showing carcass parameters that qualify them for slaughter. Meat from dairy steers has soft texture. The use of ultrasound for predicting the Longissimus dorsi muscle area and subcutaneous fat thickness measured between the 12th and 13th ribs provides a satisfactory accuracy. / Objetivou-se, nessa pesquisa, avaliar as características quantitativas e qualitativas da carcaça de novilhos de origem leiteira, recebendo dietas à base de palma forrageira e silagem de sorgo, associadas ou não à uréia e/ou farelo de algodão, bem como a utilização da ultrassonografia para estimativa de parâmetros da carcaça de bovinos jovens Girolando destinados ao corte. O estudo foi conduzido na Estação Experimental de Caruaru, pertencente ao Instituto Agronômico de Pernambuco – IPA, localizado na cidade de Caruaru, Pernambuco. Foram utilizados 18 novilhos, não castrados, da raça girolando 5/8, com peso médio inicial de 320 ± 32 kg e 24 meses de idade, aproximadamente. Os animais foram confinados por 84 dias, divididos em três períodos de 28 dias, alojados em baias individuais providas de comedouro e bebedouro. Para obtenção das imagens de ultrassom foi utilizado o equipamento Aquila Vet da Esaote Europe, com transdutor de 18 cm de comprimento, com guia acústica acoplada para melhor adaptação à anatomia do animal e frequência de 3,5 MHz. Foram realizadas medidas ultrassonográficas da área de olho de lombo (AOL-US), espessura de gordura subcutânea (EGS-US) e espessura de gordura da garupa (EGG-US), que foram correlacionadas com os pesos do dianteiro e do traseiro, e com o rendimento do traseiro. Também foram realizadas correlações entre as medidas de AOL e EGS medidas por ultrassom e na carcaça. Após o abate, registrou-se o peso da carcaça quente, o peso dos quartos, o comprimento da carcaça, perna e do coxão. A qualidade da carne foi avaliada através do pH final, da cor, da perda por cozimento, da capacidade de retenção de água e da força de cisalhamento. Foi realizada a estimativa da composição da carcaça através da separação dos tecidos que compõem a seção entre a 9a e 11a costelas (seção HH). Os efeitos das dietas experimentais não diferiram entre si, mostrando que, palma associada à silagem e à ureia, produziu característica qualitativa da carne e quantitativa da carcaça de bovinos jovens Girolando semelhante às das dietas suplementadas com farelo de algodão, exceto, o peso do traseiro, apresentando parâmetros de carcaça que o qualificam para o corte. A carne dos novilhos de origem leiteira apresenta textura macia. A utilização da ultrassonografia para a predição da área do músculo Longissimus dorsi e da espessura de gordura subcutânea medida entre a 12ª e 13ª costelas proporciona acurácia satisfatória.

Uruguay es el séptimo país exportador de carne vacuna del mundo y la producción agropecuaria se realiza mayoritariamente en base a pasturas naturales. Los elevados precios internacionales de la carne y la apertura de nuevos mercados en los últimos años, han provocado la intensificación de los sistemas de engorde. Hoy conviven los sistemas pastoriles tradicionales con los de engorde a corral, pasando por una serie de sistemas intermedios con distinto grado de intensificación. El desafío es mejorar la eficiencia del proceso de producción y la calidad del producto, sin afectar las peculiares características de los sistemas extensivos (bajo costo de producción, calidad nutricional de la carne) y sin comprometer el Bienestar animal y el medio ambiente. Es así que el presente trabajo de tesis pretende caracterizar estas diferentes alternativas de intensificación en lo que se refiere a Bienestar animal y calidad de carne, dado el creciente impacto de ambas temáticas en los precios del producto y en las preferencias de los consumidores de los países destino de las exportaciones. Para ello, se realizaron 2 experimentos en Uruguay durante los años 2005-2006 y 2006-2007, respectivamente. En el primer trabajo se utilizaron 84 novillos de raza Británica asignados a cuatro dietas con niveles incrementales de grano, desde una pradera artificial sin uso de suplemento, hasta un tratamiento de alimentación a corral en base a concentrado y heno. La ganancia de peso de los animales aumentó con el nivel energético de la dieta determinando diferentes fechas de faena para todos los tratamientos. Animales de temperamento más calmo tuvieron mayores ganancias de peso independientemente del nivel de alimentación. Los animales confinados mostraron una mayor dificultad para habituarse a las condiciones de producción, según indicadores fisiológicos relativos al estrés. Dichas dificultades pueden atribuirse en parte a la privación de realizar comportamientos probablemente relevantes para / Campo Gigena, MD. (2009). El bienestar animal y la calidad de carne de novillos en Uruguay con diferentes sistemas de terminación y manejo previo a la faena [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/4326 / Palancia

Improvement of feeding regimens for production animals has been hindered by a lack of fundamental knowledge about how the capacity to regulate nutrient absorption across cell membranes affects the function of nutrient metabolizing enzymes. The objective is to determine if the activities and protein content of system X-AG glutamate transporter, its regulatory protein (GTRAP3-18 and ARL6IP1), glutamine synthetase (GS) and glutathione (GSH) content, changes in liver (Experiment 1), longissimus dorsi (LM) and subcutaneous adipose tissue (SF) (Experiment 2) as beef steers transitioned from predominantly-lean (growing) to -lipid (finished) tissue accretion phases. In liver (Experiment 1), system X-AG activity in canalicular membranes was abolished as steers developed from growing to finished stages but did not change in basolateral membranes. EAAC1 protein content in liver homogenates decreased in finished vs. growing steers, whereas GTRAP3-18 and ARL6IP1 content increased and GLT-1 content did not change. Concomitantly, hepatic GS activity decreased in finished steers whereas GS protein content did not differ. Hepatic GSH content did not differ in finished vs. growing steers. These results demonstrate a negative functional relationship between GTRAP3-18 and system X-AG activity with glutamine synthesis capacity in livers of fattened cattle. In addition to liver, skeletal muscle and adipose tissues play important roles in maintaining whole-body glutamate and nitrogen homeostasis. In Experiment 2, Western blot analysis of LM homogenates showed decreased EAAC1 and GS content, whereas GTRAP3-18 and ARL6IP1 did not differ in finished vs. growing steers. GSH content in LM was increased in finished vs. growing steers in concomitance with increased mRNA expression of GSH-synthesizing enzymes. In SF, GTRAP3-18 and ARL6IP1 content was increased, whereas EAAC1 and GS content did not differ. Concomitantly, GSH content in SF was decreased in finished vs. growing steers in parallel with decreased mRNA expression of GSH-metabolizing enzymes. These results demonstrate that the negative regulatory relationship between GTRAP3-18 and ARL6IP1 with EAAC1 and GS expression, which exists in liver, does not exist in LM and SF of fattened cattle; and antioxidant capacity in LM and SF changes and differs as steer compositional gain shifts from lean to lipid phenotype. To further explore the upstream regulatory machinery of EAAC1, transcriptome analysis (Experiment 3) was conducted to gain a greater understanding of hepatic metabolic shifts associated with the change in whole-body compositional gain of growing vs. finished beef steers. The expression of upstream regulators of EAAC1 was decreased in a manner consistent with the decreased EAAC1 activity in Experiment 1. Bioinformatic analysis found that, for amino acid metabolism, finished steers had increased capacities for ammonia, arginine, and urea production, and shunting of amino acid carbons into pyruvate. For carbohydrate metabolism, capacity for glycolysis was inhibited, whereas glycogen synthesis was stimulated in finished steers. For lipid metabolism, finished steers showed decreased capacity for fatty acid activation and desaturation, but increased capacity for fatty acid b-oxidation and lipid storage. In addition, redox capacity and inflammatory responses were decreased in finished steers. Collectively, these data describe novel regulatory relationships of system X-AG in liver and peripheral tissues, and the metabolic mechanisms that control nutrient use efficiency, as beef steers develop from lean to lipid phenotypes.

No description available.