Orientador: Danilo Domingues Millen / Resumo: O objetivo deste estudo foi avaliar a classificação das baias com base no consumo logo nas semanas iniciais do confinamento de machos castrados e novilhas, sobre o desempenho, e desenvolver modelos de predição da ingestão de matéria seca (IMS), procurando melhorar sua acurácia por meio da inclusão da fase de confinamento em que os animais se encontram. Isso possibilitaria a identificação de “baias problemas”, ou de desempenho superior, facilitando a tomada de decisão na gestão. Para isso foram utilizados dados de 3.650 baias de confinamentos comerciais dos USA (2.256 de machos castrados e 1.394 de novilhas), os quais foram confinados entre os anos de 2009 a 2014. Os dados de IMS e de energia líquida de ganho (ELg) médios do período de terminação foram ajustados de acordo com o peso vivo inicial e dias em alimentação (DEA) pelo PROC NLIN do SAS (2009) separadamente para machos castrados e novilhas. Tanto a IMS como a ingestão de ELg médias ajustadas do período de terminação foram correlacionados com a ingestão das semanas de 5 a 12 pelo PROC CORR, e de acordo com a semana de maior correlação as baias foram classificadas em quartis: Superior ¼, Alta ¼, Média ¼ e Baixa ¼ do maior para o menor consumo e avaliado o desempenho pelo PROC MIXED. Para o desenvolvimento dos modelos foi utilizado o PROC CORR para identificar a correlação de cada variável (PVI, IMS de 8 a 28 dias, sexo, IMS da semana anterior) com a IMS e ordenar a inclusão delas no modelo, e por meio do PROC MIXED foi t... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

A reatividade, considerada como uma característica comportamental apresentada pelos bovinos diante das práticas de manejo, mais evidente nos animais de raças zebuínas, em associação com medidas fisiológicas pode se mostrar como um indicativo de estresse, dor ou desconforto, além de estar intimamente relacionada a diversas respostas produtivas apresentadas pelos animais dessa espécie. Desse modo, há necessidade de agregar essa característica, facilmente observável, ao conjunto de fatores que determinam o desempenho do animal. Para tanto, o presente estudo teve como objetivo avaliar a reatividade de novilhos Nelore confinados em dois diferentes sistemas (Curral ou Baia como tratamentos), e sua relação com o cortisol plasmático, temperatura corporal e desempenho. Foram avaliados 36 novilhos quanto às reatividades apresentadas durante o manejo de pesagem, a cada 28 dias, utilizando uma escala de Escores de Reatividade (ER) variando de 1 a 5, sendo 1 o valor atribuído ao animal mais calmo e o 5, ao animal mais reativo. Também foram coletadas amostras de sangue para posterior dosagem do cortisol plasmático, além do acompanhamento dos ganhos de peso durante todo o período. Não foram encontradas diferenças significativas da reatividade quanto ao sistema de alojamento, porém houve uma relação desse mesmo parâmetro com o tempo de permanência no confinamento para os animais nos dois tratamentos. A reatividade, quando relacionada aos valores de cortisol, não foi diferente entre os tratamentos, entretanto, esse resultado foi significante dentro do grupo dos animais alojados em Baias. O tempo de confinamento influenciou os níveis de cortisol apenas nos animais alojados em Curral. Os níveis de cortisol foram diferentes entre os tratamentos, e quando relacionados ao tempo de confinamento, evoluíram de forma inversa, tendo diminuído nas baias e aumentado nos currais. Não houve interação entre reatividade e desempenho ou entre reatividade e temperatura corporal, que foi influenciada pelos níveis de cortisol. / Reactivity as a behavioural trait of bovines presented during the handling and more obviously in Zebu cattle, in association with physiological measures can reveal as an indicative of stress, pain or discomfort, beyond being strongly related with several productive answers presented by the animals of this specie. Therefore, it is necessary to add this trait to the group of responsible factors for animals\' performances. The present study was conducted to evaluate the reactivity of Nellore steers in different feedlot systems (Stockyard and Individual pen as treatments) and its relationship with plasmatic cortisol, body temperature and performance. Thirty six Nellore steers had their reactivity evaluated during routine weighing. Blood samples were collected for cortisol analyses and the weight gains were measured during all the period. The results showed that the reactivity score did not differ between feedlots systems but there was a relation of this trait with feedlot time. There was no difference between reactivity and cortisol levels for the treatments, but this result was significant inside of the stall animals group. Feedlot time influenced the cortisol levels only for the stockyard steers. Cortisol levels differed between treatments, having increased in stalls animals and decreasing in stockyard animals. No interactions were presented between reactivity and performance, or reactivity and corporal temperature, but this last trait presented relation with cortisol levels.

Dois experimentos foram conduzidos com o objetivo de avaliar os efeitos do uso combinado de salinomicina e virginiamicina sobre o metabolismo ruminal, a digestibilidade, o comportamento ingestivo e as características sanguíneas de novilhos Nelore alimentados com dietas de alto concentrado. No experimento I, oito novilhos Nelore com 322 ± 26 kg de peso vivo (PV) inicial foram alocados no delineamento em quadrado latino 4 x 4 replicado, com quatro tratamentos em quatro períodos de 16 dias. Os tratamentos foram arranjados em esquema fatorial 2 x 2, com dois níveis de salinomicina (0 e 13 ppm) e dois níveis de virginiamicina (0 e 15 ppm) na matéria seca (MS) das dietas, que continham 80% de concentrado na MS. No experimento II, oito novilhos Nelore com 434 ± 35 kg de PV inicial foram alocados no mesmo delineamento, mas com períodos de 21 dias. Os tratamentos foram arranjados em esquema fatorial 2 x 2, com dois níveis de concentrado (70 e 90%) e dois níveis de virginiamicina (0 e 15 ppm) na MS das dietas. A salinomicina foi incluída em todas as dietas (13 ppm). Em ambos os experimentos, foram avaliados o consumo individual, a degradabilidade ruminal in situ, a digestibilidade aparente, a fermentação ruminal, o comportamento ingestivo, a população de protozoários ciliados ruminais e as características sanguíneas. As análises estatísticas foram realizadas pelo procedimento MIXED do SAS. No experimento I, houve efeito de nível de salinomicina e virginiamicina sobre as degradabilidades efetiva (DE) e potencial (DP) da fibra insolúvel em detergente neutro (FDN), sendo que os menores valores (P ≤ 0,05) foram observados para os animais tratados com os aditivos. A digestibilidade da proteína bruta (PB) foi maior (P = 0,01) para os novilhos que receberam salinomicina. Animais tratados com virginiamicina apresentaram maior (P = 0,01) concentração ruminal de propionato e menores (P ≤ 0,05) concentrações de acetato, butirato e lactato. Esses animais também apresentaram maior (P ≤ 0,03) tempo total de ruminação (TTR) e mastigação (TTM) e maior (P = 0,05) concentração de lactato no sangue. No experimento II, o aumento no teor de concentrado das dietas promoveu aumento (P = 0,01) no consumo de MS e nas digestibilidades aparentes da MS e PB, bem como redução (P < 0,01) na DE da FDN e PB. Animais tratados com ambos os aditivos apresentaram menor (P = 0,03) DE da FDN. As concentrações ruminais de acetato foram reduzidas (P < 0,01) com a inclusão de virginimicina, mas novilhos tratados com ambos os aditivos e alimentados com dieta contendo 90% de concentrado apresentaram aumento (P < 0,01) nas concentrações de propionato. O aumento no teor de concentrado promoveu redução (P < 0,01) no TTR e TTM dos animais, bem como na população de protozoários ciliados do rúmen e no pH sanguíneo. O uso combinado de salinomicina e virginiamicina apresentou efeitos positivos sobre a fermentação ruminal, especialmente quando a dieta com maior proporção de concentrado foi utilizada. / Two experiments were conducted to evaluate the effects of the combined use of salinomycin and virginiamycin on ruminal metabolism, digestibility, feeding behavior, and blood characteristics of Nellore steers fed high concentrate diets. In experiment I, eight Nellore steers with 322 ± 26 kg of initial body weight (BW) were allotted to a replicated 4 x 4 Latin square, with four treatments and four 16-day periods. Treatments were arranged in a 2 x 2 factorial design, with two salinomycin levels (0 and 13 ppm) and two virginiamycin levels (0 and 15 ppm) in the diet dry matter (DM), which contained 80% concentrate on a DM basis. In experiment II, eight Nellore steers with 434 ± 35 kg of initial BW were allotted to the same experimental design, but with 21-day periods, in a 2 x 2 factorial arrangement of treatments, with two concentrate levels (70 and 90%) and two virginiamycin levels (0 and 15 ppm) in the diet DM. Salinomycin was included in all diets (13 ppm). In both experiments, individual intake, in situ ruminal degradability, apparent digestibility, ruminal fermentation, feeding behavior, ciliated protozoa counts, and blood characteristics were evaluated. Statistical analyses were conducted using the MIXED procedure of SAS. In experiment I, there were effects of salinomycin and virginiamycin on effective and potential degradabilities (ED and PD, respectively) of the neutral detergent fiber (NDF), with lower values (P ≤ 0.05) observed for animals receiving the additives. Crude protein (CP) digestibility was higher (P = 0.01) for salinomycin-treated steers. Animals receiving virginiamycin showed higher (P = 0.01) ruminal concentrations of propionate and lower (P ≤ 0.05) ruminal concentrations of acetate, butyrate, and lactate. These animals also showed higher (P ≤ 0.03) total time spent ruminating (TTSR) and total time spent chewing (TTSC), as well as higher (P = 0.05) blood lactate concentrations. In experiment II, increasing concentrate levels increased (P = 0.01) DM intake and DM and CP digestibilities, but also decreased (P < 0.01) ED of the NDF and CP. Ruminal concentrations of acetate were reduced (P < 0.01) due to the inclusion of virginiamycin, but steers receiving both feed additives within the 90% concentrate group showed increased (P < 0.01) ruminal concentrations of propionate. Increasing concentrate levels decreased (P < 0.01) TTSR and TTSC, as well as ciliated protozoa counts and blood pH. The combined use of salinomycin and virginiamycin showed positive effects on ruminal fermentation, especially when animals were fed the higher concentrate diet.

Beef cattle production is highly criticized because of the high use of land and water resources, and by the pollution (e.g., the gas methane in a cow’s breath and nitrogen in urine) produced by cows fed in feedlots. In contrast to feedlots diets and grasses, some plants (e.g., legumes) contain bioactive compounds (condensed tannins) that reduce pollution and enhance animal nutrition. In my research, I observed that cows grazing a tannin-containing legume (birdsfoot trefoil; BFT) had methane emissions similar to cows fed a feedlot ration with comparable weight gains. Cows in the BFT treatment gained more weight than cows grazing grass (meadow brome) or a legume without tannins (cicer milkvetch). Additionally, I estimated the potential areas in the state of Utah than can sustain birdsfoot trefoil production, with 412,250 ha distributed mostly in the Box elder, Cache, Millard and Sanpete counties. Thus, feeding tannin-containing legumes to cows is a viable alternative to feedlot rations, with greater levels of productivity than other pasture-based systems, which can lead to a more sustainable production of beef.

Fetal programming is a relatively new and quickly growing field of research in the livestock industry. The concept of fetal programming is simply defined as the effects a change in maternal nutritional intake has on offspring, whether it be a genetic or physical change. The intention of this study was to specifically look at the effects of nutrient restriction of cows during the second trimester of gestation on the growth and performance of the resulting calves. In this study, thirty-two cows of predominantly angus influence from the Utah state university herd were chosen, naturally bred to a pure bred angus sire, and then allocated into two treatments: maintenance and restricted. These groups were treated uniformly for first and third trimesters of gestation, while in the second trimester, they were managed in a way that the maintenance group maintained a greater level of body condition and weight compared with the restricted group. Calf growth and performance was measured and compared for effects of fetal programming. Previous studies in beef found positive effects on carcass characteristics. However, little work has been done to ensure that fetal programming is not detrimental to calves early in life. Though this study did find that nutrient restriction resulted in more excitable cattle, no negative effects caused by programming were found in growth and performance of the offspring.

The goal of this study was to investigate feedlot performance and meat quality of calves born to cows that underwent a nutrient restriction during the second trimester of gestation which may be occurring in the Intermountain West. Thirty-four angus influenced calves from the same sire were used for this study. The calves were born from cows that were separated into either a maintenance group, and kept on an irrigated pasture, or a restricted group, that was placed on an unirrigated pasture and allowed to lose one body condition score during the second trimester of pregnancy. This study begins with the calves on day 85 of the finishing portion of the feedlot phase. During the finishing feedlot phase, calves were individually housed, fed ad libitum, and feedlot performance measurements were taken every 28 days. Carcasses from the calves were evaluated for yield and quality. A loin from each carcass was collected, aged, frozen, and cut into individually packaged steaks that were used to assess meat quality. There was no difference in feedlot performance and carcass measurements for either maintenance and restricted calves. Meat quality measurements revealed no difference in color, instrumental tenderness values, or composition of steaks from either group. A trained sensory panel found that ten characteristics of flavor were similar for both treatments. There was however, a trend for steaks from nutrient restricted cattle to have more of a bloody/serumy flavor. The trained sensory panel also found that there was a difference in tenderness of steaks from nutrient restricted animals being perceived as more tender than animals from maintenance cows. The results of this study demonstrate that nutrient restriction during mid-gestation does not have negative effects on feedlot performance, carcass characteristics, or meat quality measurements. These results also indicate that steaks from calves born to nutrient restricted cows may be perceived as more tender.

Objetivou-se estudar efeitos negativos do transporte ao confinamento e do período de adaptação neste, assim como avaliar a presença de bactérias possivelmente patogênicas na nasofaringe durante este processo. Foram empregados 48 bovinos machos da raça Nelore, com 372 ± 27 kg de peso corpóreo, os quais viajaram ao confinamento, em caminhões-gaiola, em torno de 167 km, com duração de 4 h. Os mesmos foram pesados na saída, chegada e 48 h após. Amostras de sangue da veia jugular e swab da nasofaringe foram obtidos nos mesmos momentos e no 10º d, com exceção da saída. Para a obtenção do swab foi empregado zaragatoa acoplada à pinça Allis, ambas com 15 cm. O volume globular (VG) foi analisado no sangue total e a partir dessa variável foi calculado o déficit de volume plasmático (DVP). No soro foram determinados os teores de albumina e globulinas, calculando-se sua relação. O material do swab foi semeado em ágar sangue de carneiro (5%) com base Columbia e ágar McConkey e alíquotas desta cultura foram submetidas à técnica MALDI-TOF MS. Para a identificação bacteriana pelo espectro proteico, foi utilizado o programa BioTyper™. As colônias bacterianas identificadas pelo MADI- TOF MS como pertencentes a família Pasteurellaceae foram submetidas à identificação pelo sequenciamento parcial do gene 16S rRNA. Dessa família foi isolada, pela primeira vez no Brasil, apenas Mannheimia varigena em 31,2 % dos animais, no dia da chegada ao confinamento, desaparecendo em seguida. Identificaram-se também bactérias do gênero Bacillus ssp., que inibe o crescimento do gênero Mannheimia spp., principalmente dos animais negativos (93,7%) e em menor frequência (46,7%) dos positivos. Bovinos positivos à M. varigena perderam percentualmente mais peso (p = 0,045) durante a viagem que os negativos, não existindo diferença na 48ª h (p = 0,117). Quanto mais leve foi o bovino maior foi a sua perda de peso (p < 0,0001) e seu grau de desidratação (p = 0,005) durante a viagem, recuperando essa última variável parcialmente durante a adaptação. Nesse período a desidratação espelhou positivamente o peso perdido (r = 0,65). A viagem e a adaptação estimularam a produção de globulinas, em especial nos positivos no 10º d (p =0,023). A desidratação identificada foi de grau leve em 20% dos animais e moderada em 17,8%. O DVP identificou melhor o grau de desidratação que o VG. O estresse do transporte e a adaptação não foram suficientes para desencadear quadros respiratórios nas reses positivas para M. varigena. / This survey studied the negative effects of transportation and adaptation of steers shipped to a feedlot, as well analyzed the presence of possible pathogenic bacteria in the nasopharyngeal during these events. Forty-eight male Nellore steers (372 ± 27 kg B.W.) travelled 167 km in trucks to the feedlot, for 4 h. The cattle was weighted on the departure, arrival and 48 h later. Jugular blood samples and swab of the nasopharyngeal were collected on the same schedule, but the departure, and on the 10th d. The nasopharyngeal samples were obtained with the use of a swab attached to an Allis clamp, both with 15 cm length. The globular volume (GV) was measured in the total blood and from this variable, the plasma volume deficit (PVD) was calculated. Serum albumin and globulin, as well its ratio were also determined. The swab was plated onto sheep blood agar (5%), Columbia base and MacConkey agar, and samples of this culture were analyzed by a MALDI-TOF MS technique. For bacterial identification by the protein mass spectrum biomarker a BioTyper™ program was used. The colonies identified as Pasteurellaceae family were submitted for identification by partial sequencing of gene 16S rRNA. From this family was isolated, by the first time in Brazil, Mannheimia varigena in 31.2% of the steers, on the arrival, which disappeared thereafter. Bacteria from the genus Bacillus, which inhibits the genus Mannheimia, were also identified in the negative (93.7%) and less frequently (46.7%) in positive steers. Positive cattle to M. varigena lost more weight during the shipment than the negatives (p = 0.045), but no difference was found at the 48th h (p = 0.117). The lighter the steer, the greater the lost of weight (p < 0.0001) and the degree of dehydration (p = 0.005), recovering partially the hydration at the 48th h. During adaptation, the higher the dehydration, the bigger the weight loss (r =0.65). The trip and adaptation enhanced the globulin levels, mainly in the positive steers at day 10 (p= 0.023). The degree of dehydration was light in 20% of the animals and moderate in another 17.8 %. The PVD identified better the the degree of dehydration rather than VG. The stress of transport and adaptation was not enough to trigger respiratory disease in the positive steer to M. varigena.

Selenium (Se) is an essential mineral with functions for both animals and humans. There are several regions in the world deficient in this mineral and studies have related Se supplemented with reducing cholesterol. Thus, the objective of this study was to evaluate the Se effect in different levels and sources in the diet finishing of Nellore cattle on the performance and meat quality. It was used 63 Nellore cattle (412 kg and ± 24 months of age) in a completely randomized design with two sources (sodium selenite and selenium-enriched yeast) and four supplementation levels (0; 0.3; 0.9 and 2.7 mg Se/kg DM). There were no changes in performance and carcass characteristics. The Se level reduced (P<0.01) lipid and proteins oxidation (TBARS and carbonyl) compared to the control treatment on retail display storage (0, 2, 4 and 6 days). Organic Se, regardless of level, provided Se 138% higher (P<0.0001) in meat and 22.6% higher (P<0.0001) in serum than inorganic Se. The activity of glutathione peroxides (GPx) in muscle was 288% higher for animals supplemented with selenium and consequently, the cholesterol concentration in L. dorsi was 10.2% lower (P<0.001). The serum HMG-CoA reductase concentration was 32.7% lower in animals receiving Se supplementation (organic or inorganic). In conclusion, Se supplementation in beef cattle diet is a way of naturally producing selenium-enriched meat and with better quality for human consumption. / O selênio (Se) é um mineral essencial com funções para animais e humanos. Existem várias regiões do mundo deficientes neste mineral e estudos têm relacionado a suplementação de Se com a redução do colesterol. Assim, o objetivo deste estudo foi avaliar o efeito de diferentes teores e fontes de Se na dieta de terminação de bovinos Nelore sobre o desempenho e a qualidade da carne. Foram utilizados 63 animais da raça Nelore (412 kg e ± 24 meses de idade) em delineamento inteiramente casualizado, com duas fontes (selenito de sódio e selênio levedura) e quatro teores de suplementação (0; 0,3; 0,9 e 2,7 mg Se/kg MS) em confinamento, durante 84 dias. Não houve alterações no desempenho e nas características de carcaça. O teor de Se reduziu (P <0,01) a oxidação lipídica e proteica (TBARS e carbonila) em comparação ao tratamento controle durante o armazenamento em simulação de exposição no varejo (0, 2, 4 e 6 dias). O Se orgânico, independentemente do teor, forneceu valor de Se 138% superior (P <0,0001) na carne e 22,6% superior (P <0,0001) no soro em relação ao Se inorgânico. A atividade glutationa peroxidase (GPx) no músculo foi 288% maior nos animais suplementados com selênio e, consequentemente, a concentração de colesterol na carne foi 10,2% menor (P <0,001). A concentração sérica de HMG-CoA redutase foi 32,7% menor nos animais que receberam suplementação de Se (orgânico ou inorgânico). Foi concluído que a suplementação com Se na dieta de bovinos de corte é uma forma de produzir carnes enriquecidas com selênio naturalmente e com melhor qualidade para consumo humano.

This study assessed the value of triticale dried distillers grains with solubles(DDGS) in a feedlot finishing diet using 144 intact, and 16 ruminally cannulated crossbred yearling steers. Substituting triticale DDGS for a portion of dry-rolled barley grain (20% diet DM) decreased the prevalence of ruminal acidosis and tended to increase dry matter intake and fat deposition, but increased the incidence and severity of liver abscesses. Further substitution of triticale DDGS for barley silage (5 and 10% diet DM) increased the prevalence of ruminal acidosis, but tended to improve feed efficiency without affecting carcass characteristics. These findings suggest that feedlot finishing diets containing triticale DDGS allow producers to decrease dietary forage inclusion without affecting performance, but may require use of an antimicrobial to control liver abscesses. / Animal Science

Two experiments were conducted to evaluate the effects of dietary inclusion level of a low lignin hull, high-oil groat (CDC SO-I) oat on the performance, carcass characteristics and rumen degradation characteristics of feedlot cattle. In the first trial, 200 crossbred steers (average weight of 427.3 ± 22.4 kg) were allocated to 20 pens. Five treatments, formulated by replacing barley with increasing levels of CDC SO-I oat (Barley grain:CDC SO-I oat ratios of 100:0; 75:25; 50:50; 25:75 and 0:100 ; DM basis) were used. Four pens were randomly allocated to each treatment diet. Over the entire study there was a linear decrease (P< 0.01) in DMI and ADG with increasing inclusion level of CDC SO-I oat, whereas feed efficiency (gain:feed) decreased (P= 0.03) quadratically. Days on feed also increased (P= 0.03) quadratically for the steers fed the higher levels of CDC SO-I oat. Increasing the inclusion level of CDC SO-I oat in the diet also decreased (P< 0.01) carcass weight, dressing percentage and grade fat linearly. However, there was no effect of treatment on rib eye area and lean yield percentage. There was no significant effect of treatment on marbling score. While the results of this trial point to a negative effect of CDC SO-I oat on finishing performance, there were minimal differences between cattle fed 100% barley as the concentrate versus those fed 75% barley: 25% oat blend.<p> Trial 2 involved a metabolism trial to determine the effect of CDC SO-I oat inclusion level on rumen fermentation parameters of 5 fistulated heifers fed the same diets used in Trial 1. A 5 × 5 Latin square experiment design was used. Rumen degradation parameters (rumen pH, VFA, osmolality and ammonia nitrogen levels) and feeding behavior (time spent eating, ruminating, chewing and drinking) were measured. Mean rumen pH for the barley-based diet was 5.88 which was not different (P> 0.05) than the mean pH of 5.5 for the oat-fed cattle. Treatment did not affect (P> 0.05) time spent below pH cutoff values of 5.8, 5.5 and 5.2. No effect of oat inclusion level (P> 0.05) was observed on total VFA levels, molar proportion of individual fatty acids and osmolality while isobutyrate (P= 0.05) and ruminal ammonia nitrogen concentrations decreased linearly (P= 0.02) with the higher inclusion of CDC SO-I oat. Time spent eating was linearly (P< 0.01) increased with higher inclusion level of CDC SO-I oat.<p> Over all, the results of this study indicate that the replacement of barley by CDC SO-I oat in finishing diets decreases dry matter intake and as a result leads to reduced ADG, increased days on feed and lower slaughter and carcass weights. The reduced performance might be the result of higher fat content, high hull and/or faster degradation rate of oat starch leading to subacute ruminal acidosis in cattle fed higher levels of oat. However, replacing barley with CDC SO-I oat does not significantly change the rumen environment. The results of this study indicate that CDC SO-I oat can be successfully included up to a maximum level of 25% without any adverse effect on performance and carcass characteristics in the diets of finishing cattle.