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1.
Vet Clin North Am Food Anim Pract ; 35(3): 575-592, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31590903

RESUMO

Vaccination is a critical component of cattle health management. Effective cattle vaccine programs should consider the timing of vaccination in relation to expected disease challenge, risk for wild-type exposure of various bovine pathogens, and host factors during vaccination. Nearly all consulting veterinarians recommend vaccination of stressed, high-risk calves on feedlot arrival. However, this recommendation fails to consider several factors associated with vaccine efficiency. Further research evaluating vaccine interactions in stressed cattle and potential additive effects of endotoxin from multiple bacterin administration may reveal new evidence-based vaccination guidelines for cattle in the various segments of beef and dairy production systems.


Assuntos
Bovinos/imunologia , Carne Vermelha , Vacinação/veterinária , Animais , Doenças dos Bovinos/prevenção & controle , Vacinação/métodos , Vacinas Virais/administração & dosagem
2.
J Anim Sci ; 97(11): 4682-4690, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31608380

RESUMO

Auction-derived steers (n = 36; initial BW = 284 ± 11 kg) were received to compare performance, rumination characteristics, and rumen pH differences due to alternative ration energy densities and feed management strategies during a 56 d receiving study. Cattle were weighed on day -1 and randomized to 1 of 3 treatments. Time spent ruminating was quantified with a three-axis accelerometer ear-tag. Rumen pH and temperature were logged in a random subset (n = 6 per treatment) by a ruminal bolus. Cattle were processed identically and housed in individual pens. The modified-live virus respiratory vaccination was delayed until day 28. The finisher (FIN) cattle were provided their daily feed as a high energy density (1.39 Mcal NEg/kg) diet. The finisher + hay (FIN+H) cattle were provided the same diet but were also offered 0.5% BW DM as coastal Bermudagrass hay on days 1, 4, 7, 10, 13, 16, 19, 22, 25, and 28. The control (CON) cattle were fed a low energy density (0.93 Mcal NEg/kg) diet from day 0 to 7, then transitioned to the FIN diet by replacing an additional 25% of the daily feed call with FIN every 7 d until 100% of the diet was FIN on day 29. Feed offering for CON was increased more aggressively (0.45 kg DM daily for days 1 to 7, every other day for day 8 to 14) than FIN and FIN+H (0.45 kg DM every other day for days 1 to 7, daily for days 8 to 14). Performance and DMI were analyzed using PROC MIXED in SAS with treatment as a fixed effect. Rumination, pH, and temperature models included repeated measures. There was no treatment difference observed for BW, average daily gain (ADG), or G:F (P ≥ 0.12). There was a treatment × day interaction (P = 0.06) for rumen temperature, where FIN increased more rapidly following vaccination on day 28 compared to CON (P ≤ 0.04). Daily rumination minutes were greater (P < 0.01) for CON than FIN from days 7 to 22. Additionally, CON had the greatest (P < 0.01) hourly rumination from 2000 to 0800 hours. Lower minimum daily rumen pH occurred in FIN+H (P ≤ 0.06) on weeks 1, 2 and 6 to 8 compared to CON. There were minimal statistical differences in area under the curve or time below pH thresholds, probably due to large animal-to-animal variation. Hourly rumen pH was reduced (P ≤ 0.05) for FIN vs. FIN+H and CON during the initial 28 d, but greater (P = 0.05) for FIN and FIN+H during the final 28 d. When cattle are individually fed, greater energy density rations can be fed initially without compromising performance, but this needs to be evaluated in group pens where greater DMI variation is probable.


Assuntos
Ração Animal/análise , Bovinos/fisiologia , Criação de Animais Domésticos , Animais , Bovinos/crescimento & desenvolvimento , Dieta/veterinária , Ingestão de Alimentos , Metabolismo Energético , Concentração de Íons de Hidrogênio , Masculino , Rúmen/metabolismo , Temperatura Ambiente
3.
J Anim Sci ; 97(8): 3596-3604, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31074787

RESUMO

Transition of newly received feedlot cattle from a forage- to grain-based diet is challenging, and the appropriate roughage level in receiving diets is debatable. Nutritionists must consider the paradox of dietary transition and roughage level to mitigate ruminal acidosis, yet concomitantly low feed intake presents difficulty in achieving nutrient requirements when metabolic demand is increased due to inherent stress and disease challenge during the receiving period. Previous research suggests that performance is improved at the expense of increased morbidity for newly received cattle consuming diets with less roughage and greater starch concentration. The clinical signs of bovine respiratory disease (BRD) and acute acidosis are analogous; therefore, it is probable that acidotic cattle are incorrectly diagnosed with BRD in both research and production settings. Additional research efforts have attempted to elucidate alterations in microbial populations and digestion, physiological response to inflammatory challenge, and immunological response to infectious bovine rhinotracheitis virus challenge in cattle consuming diets of various roughage levels. Furthermore, our understanding of the rumen microbiome is improving rapidly with culture-independent assays, products such as direct-fed microbials are available, and increased availability and use of fibrous byproduct ingredients requires further attention. Beef cattle nutritionists and producers should consider that the health benefit of receiving diets containing greater levels of roughage and lower energy may not compensate for the reduction in performance compared with feeding receiving diets with lower roughage and greater energy.


Assuntos
Acidose/veterinária , Doenças dos Bovinos/imunologia , Fibras na Dieta/análise , Microbioma Gastrointestinal , Rinotraqueíte Infecciosa Bovina/imunologia , Acidose/imunologia , Ração Animal/análise , Bem-Estar do Animal , Animais , Bovinos , Dieta/veterinária , Digestão , Ingestão de Alimentos , Grão Comestível , Ingestão de Energia , Imunidade , Inflamação/veterinária , Rúmen/metabolismo , Amido/metabolismo , Estresse Fisiológico
4.
J Anim Sci ; 97(5): 2015-2024, 2019 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-30911760

RESUMO

The study objectives were to determine the effect of oral hydration therapy and bovine respiratory disease (BRD) on rumination behavior, rumen pH, and rumen temperature. A random subset of high-risk, auction-sourced bulls from 3 truckload blocks (initial BW = 188.9 ± 19.1 kg) were fitted with a collar containing a 3-axis accelerometer to quantify rumination time and activity (n = 58) and administered a rumen pH and temperature data logging bolus (n = 33). At arrival, subset calves (n = 2 per pen) were balanced across treatment pens (n = 15 per treatment; n = 10 animals per pen) and randomized to receive 0.57 L water/45.4 kg BW from a modified oral drenching apparatus (H2O) or no water administration (CON). Standard arrival processing procedures were implemented including surgical castration. Modified-live virus respiratory vaccination was delayed until day 28. Technicians assigned a clinical illness score (CIS) daily; calves with CIS ≥ 2 and rectal temperature ≥ 40 °C were considered a BRD case (RCASE) and treated with an antimicrobial. The fixed effect of BRD cases vs. nontreated cohorts (RCON) was determined retrospectively using data from the accelerometer collar (n = 19 and 29) and rumen bolus (n = 12 and 21, for RCASE and RCON, respectively). Daily means and hourly means across days throughout the 56-d observation period were generated. Fixed effects were analyzed using the mixed model procedure with repeated measures. Daily rumen temperature was altered (P = 0.04) such that peak rumen temperature occurred earlier for H2O, whereas CON had increased (P ≤ 0.01) rumen temperature following delayed vaccination on day 28. Calves diagnosed with BRD had a transiently decreased (P = 0.04) active minutes between days 9 and 32, decreased (P < 0.01) active minutes between 0800 and 2000 h, decreased (P < 0.01) rumination time between 2000 and 0400 h, greater (P < 0.01) rumen temperature until delayed vaccination on day 28, and greater (P < 0.01) hourly rumen temperature between 0900 and 0300, and altered (P < 0.01) rumen pH. Earlier peak rumen temperature observed in H2O may indicate physiological modification enabling a more pronounced inflammatory response. Differences in rumination behavior and activity may be useful for early BRD detection.


Assuntos
Anti-Inflamatórios não Esteroides/administração & dosagem , Doenças dos Bovinos/prevenção & controle , Meloxicam/administração & dosagem , Doenças Respiratórias/veterinária , Vacinação/veterinária , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/terapia , Dieta/veterinária , Feminino , Concentração de Íons de Hidrogênio , Incidência , Masculino , Distribuição Aleatória , Doenças Respiratórias/epidemiologia , Doenças Respiratórias/prevenção & controle , Doenças Respiratórias/terapia , Estudos Retrospectivos , Rúmen/metabolismo , Temperatura Ambiente , Vacinas Atenuadas , Água
5.
J Anim Sci ; 97(2): 596-609, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30496421

RESUMO

Objectives of this experiment were to examine the effects of live yeast (LY) supplementation on immunological, physiological, and behavioral responses in steers experimentally challenged with Mannheimia haemolytica (MH). Thirty-six crossbred Angus steers (BW = 352 ± 23 kg) seronegative for MH were allocated within a 2 × 2 factorial arrangement: Factor 1 = roughage-based diet with LY (Saccharomyces cerevisiae boulardii CNCM I-1079, 25 g·per steer daily) or negative control (CON). Factor 2 = bronchoselective endoscopic inoculation with MH or phosphate buffer solution (PBS). Steers were fed their respective diets for 28 d prior to MH challenge on day 0. Reticulo-rumen temperature (RUT; ThermoBolus, Medria) was measured continuously at 5-min intervals and rectal temperature on days -4, 0, 1, 2, 3, 5, 7, 10, and 14 relative to MH inoculation. Compared with PBS-treated steers, the steers inoculated with MH had increased (P < 0.05) RUT from 2 to 24 h, reaching a zenith (>41 °C) 9 to 11 h post-MH challenge, whereas rectal temperature was increased (P < 0.04) in MH-inoculated steers on day 1 post-MH challenge. Supplementation with LY increased (P < 0.05) rectal temperature on days 0, 7, and 10, relative to CON steers. There were inoculation x day interactions (P < 0.01) for lymphocyte, neutrophil, leukocyte, and haptoglobin concentrations. Steers challenged with MH had increased (P < 0.05) neutrophil concentration from days 1 to 3, leukocyte concentration on days 1 and 2 and haptoglobin concentration on days 1 to 5 post-MH challenge compared with PBS-treated steers. Steers supplemented with LY exhibited increased (P < 0.02) cortisol throughout the study compared with the CON treatment. Following inoculation, MH-challenged steers exhibited reduced (P < 0.05) DMI, eating rate, frequency, and duration of bunk visit (BV) events compared with PBS-treated steers. Results from this study demonstrate that the experimental challenge model effectively stimulated acute-immune responses and behavioral changes that are synonymous with naturally occurring bovine respiratory disease (BRD). However, supplementation with LY minimally altered the impact of the MH challenge on physiological and behavioral responses in this study. Continuously measured RUT was more sensitive at detecting febrile responses to MH challenge than rectal temperature. These results serve to guide future research on behavioral and physiological alterations exhibited during a BRD infection.


Assuntos
Bovinos/fisiologia , Suplementos Nutricionais , Comportamento Alimentar , Mannheimia haemolytica/imunologia , Saccharomyces cerevisiae , Ração Animal/análise , Animais , Bovinos/imunologia , Bovinos/microbiologia , Dieta/veterinária , Ingestão de Alimentos/efeitos dos fármacos , Haptoglobinas/análise , Masculino , Rúmen/fisiologia , Regulação para Cima
6.
J Anim Sci ; 96(9): 3712-3727, 2018 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-29917102

RESUMO

The objective of this study was to evaluate a combination of best management practices strategy for steer calves grazing tall fescue pastures with a range of toxicity. The experiment was conducted over 2 grazing seasons (fall 2015 for 91 d and spring 2016 for 84 d). Steers (n = 80 within season, body weight [BW] = 197.0 ± 15.43 kg [fall] and 116.9 ± 4.88 [spring]) were stocked at 2.45 and 4.1 calves/ha in fall and spring, respectively, to 16 pastures with varying levels of toxicity based on interim ergovaline (EV) concentration within season. Pastures were assigned to either mineral (MIN, n = 8) only management (MGMT) or a cumulative MGMT (CM, n = 8). The CM treatment included an implant containing 40-mg trenbolone acetate, 8-mg estradiol, and 29-mg tylosin tartrate (Component TE-G with Tylan, Elanco Animal Health, Greenfield, IN), 150 mg/calf daily monensin (Elanco Animal Health), and 1% BW of a 50:50 corn gluten feed:soybean hull supplement (as-is basis). Data were analyzed within season using pasture as the experimental unit. For fall and spring, the EV concentration was 1,476 ± 883.2 and 1,173 ± 620.6 ppb, respectively, and ranged from 90 to 2,180 ppb. During the fall, forage allowance did not differ (P = 0.76) between CM and MIN. In the spring, however, forage allowance only differed for the month of June (P ≤ 0.05, 2.55 vs. 3.22 ± 0.177 kg DM/kg BW, for MIN and CM, respectively). In the fall, average daily gain (ADG) responded to the simple effects of EV (P = 0.01) and MGMT (P < 0.001), and ADG for MIN steers was explained by ADG = 0.41 - 0.000064 × EV, whereas ADG for CM was explained by ADG = 1.05 - 0.000064 × EV. In the spring, there was an EV × MGMT interaction (P = 0.03) for ADG. For MIN, ADG = 0.80 - 0.000278 × EV, whereas for CM, ADG = 0.94 + 0.000001835 × EV. In spring, the ADG response to CM relative to MIN increased as EV increased. The CM strategy resulted in lower blood urea nitrogen than MIN in fall and spring (P < 0.01), but prolactin and serum Cu were not affected by MGMT in either season. In conclusion, performance was improved within the fescue belt by implementing feeding strategies using implants, ionophores, and supplementation, but a detailed economic analysis is warranted. Further research is needed to evaluate CM programs under varied stocking rates and in combination with dilution of endophyte-infected fescue pastures with nontoxic grasses or legumes.

7.
J Anim Sci ; 96(3): 890-901, 2018 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-29385520

RESUMO

Crossbred beef bulls (n = 180) were blocked by initial BW (337 ± 10.9 kg; six blocks) and assigned randomly to one of three treatments on day 0: 1) INJ; received 1 mL (100 mg Zn) of a Zn solution in each testis, 2) BAN; received blood- restrictive rubber band placed around the dorsal aspect of the scrotum, 3) BUL; bulls with testicles remaining intact in a randomized complete block design (three treatment pens per block and 10 cattle per pen). A subset of 54 animals (n = 3 per pen) was fitted with accelerometers on day 0 to quantify behavior variables continuously for 28 d. Testis width and scrotal circumference, and serum haptoglobin (days 0, 1, 3, 5, 7, and 14) and testosterone concentrations (every 28 d until slaughter) were also determined for the subset. During the slaughter process, testes from INJ and BUL were collected to assess final testes weight and for histopathological evaluation. Data were analyzed using a mixed model (α = 0.05); pen served as the experimental unit for all dependent variables. Final BW was greater (P < 0.01) for INJ and BUL compared to BAN (672, 686, and 611 kg, respectively; SEM = 4.4). Overall ADG and G:F were greater (P ≤ 0.03) in INJ and BUL than BAN; whereas, DMI was similar between treatments for the study duration (P = 0.46). Histopathological evaluation (n = 13; INJ = 7; BUL = 6) indicated that INJ testes were degenerative and reproductively nonviable whereas BUL testes were normal. Serum testosterone concentrations on day 168 were similar (P = 0.14) between INJ and BUL whereas after day 14, BAN was nondetectable; however, initial serum testosterone concentrations were similarly low across treatments. Serum haptoglobin concentration was greater (P < 0.01) in INJ than BUL and BAN on days 1, 3, 5, and 7. Scrotal circumference (P = 0.08) and testis width (P = 0.07) on day 168 tended to be greater for BUL than INJ. Motion index (P ≤ 0.02) and step count (P = 0.04) was greater in BUL and INJ compared to BAN cattle during the 28 d monitoring period. No difference in standing time (P ≥ 0.85) or lying bouts (P = 0.35) occurred. Zinc injection resulted in sterilization but did not cause complete cessation of testicular function evidenced by testosterone concentrations more similar to BUL than BAN. This resulted in overall increased BW and G:F for INJ vs. BAN, yet the acute phase response was markedly greater directly after Zn injection. Collectively, Zn injection resulted in outcomes more similar to BUL than BAN, implying minimal efficacy of INJ as a castration method in older bulls arriving to the feedlot.


Assuntos
Bovinos/fisiologia , Haptoglobinas/análise , Reprodução , Testosterona/sangue , Zinco/administração & dosagem , Reação de Fase Aguda/enzimologia , Animais , Peso Corporal , Injeções/veterinária , Masculino , Orquiectomia/veterinária , Distribuição Aleatória , Escroto/metabolismo , Testículo/efeitos dos fármacos
8.
Vet Clin North Am Food Anim Pract ; 31(3): 341-50, v, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26227871

RESUMO

Despite research and increased availability of antimicrobials, the prevalence and challenges associated with BRD in stocker and feedlot operations remain. Preconditioned calves can better handle the transition from the origin ranch to the feedlot, yet there is incentive for buyers to purchase high-risk cattle at a reduced cost, and this is influenced by the proven efficacy and availability of antimicrobial metaphylaxis. The poor sensitivity of current BRD field diagnostic methods, typical pathogenesis of BRD, and labor issues are additional reasons to use metaphylaxis. Nevertheless, practitioners should consider comprehensive and novel approaches to judiciously guide decisions on metaphylactic use of antimicrobials.


Assuntos
Criação de Animais Domésticos , Antibacterianos/uso terapêutico , Complexo Respiratório Bovino/prevenção & controle , Comportamento Alimentar , Animais , Antibacterianos/administração & dosagem , Complexo Respiratório Bovino/tratamento farmacológico , Bovinos , Esquema de Medicação , Humanos , Prevalência , Fatores de Risco , Transportes , Carga de Trabalho
9.
Innate Immun ; 20(8): 888-96, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24217218

RESUMO

Activation of the innate immune system and acute phase response (APR) results in several responses that include fever, metabolic adaptations and changes in behavior. The APR can be modulated by many factors, with stress being the most common. An elevation of stress hormones for a short duration of time can be beneficial. However, elevation of stress hormones repeatedly or for an extended duration of time can be detrimental to the overall health and well-being of animals. The stress and APR responses can also be modulated by naturally-occurring variations, such as breed, gender, and temperament. These three natural variations modulate both of these responses, and can therefore modulate the ability of an animal to recover from a stressor or infection. Understanding that cattle have different immunological responses, based on naturally occurring variations such as these, may be the foundation of new studies on how to effectively manage cattle so that health is optimized and production is benefited.


Assuntos
Reação de Fase Aguda/imunologia , Reação de Fase Aguda/fisiopatologia , Bovinos/imunologia , Bovinos/fisiologia , Estresse Psicológico/imunologia , Estresse Psicológico/fisiopatologia , Reação de Fase Aguda/genética , Reação de Fase Aguda/psicologia , Animais , Estresse Psicológico/genética , Estresse Psicológico/psicologia , Temperamento
10.
J Am Vet Med Assoc ; 243(7): 1035-41, 2013 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-24050572

RESUMO

OBJECTIVE: To determine the association of CBC variables and castration status at the time of arrival at a research facility with the risk of development of bovine respiratory disease (BRD). DESIGN: Retrospective cohort study. ANIMALS: 1,179 crossbred beef bull (n = 588) and steer (591) calves included in 4 experiments at 2 University of Arkansas research facilities. PROCEDURES: Calves underwent processing and treatments in accordance with the experiment in which they were enrolled. Castration status and values of CBC variables were determined at the time of arrival at the facilities. Calves were monitored to detect signs of BRD during a 42-day period. RESULTS: The areas under the receiving operator characteristic curves for CBC variables with significant contrast test results ranged from 0.51 (neutrophil count) to 0.67 (eosinophil count), indicating they were limited predictors of BRD in calves. The only CBC variables that had significant associations with BRD in calves as determined via multivariable logistic regression analysis were eosinophil and RBC counts. The odds of BRD for bulls were 3.32 times the odds of BRD for steers. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study indicated that low eosinophil and high RBC counts in blood samples may be useful for identification of calves with a high risk for development of BRD. Further research may be warranted to validate these variables for prediction of BRD in calves. Calves that were bulls at the time of arrival had a higher risk of BRD, versus calves that were steers at that time.


Assuntos
Complexo Respiratório Bovino/sangue , Orquiectomia/veterinária , Animais , Biomarcadores , Bovinos , Estudos de Coortes , Masculino , Análise Multivariada , Estudos Retrospectivos , Fatores de Risco
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