Influence of dental carcass maturity classification on carcass traits and tenderness of longissimus steaks from commercially fed cattle.

Two hundred beef carcasses were randomly selected by dental classification (zero, two, four, six, or eight permanent incisors) from a population of 11,136 carcasses harvested by a large commercial beef processor. Warner-Bratzler shear force and trained sensory panel evaluations of longissimus thoracis steaks as well as cooking and carcass traits were evaluated for differences among dental classes. No differences in Warner-Bratzler shear force (P = 0.60), sensory panel evaluations (P = 0.64) for tenderness, or percentage of total cooking loss (P = 0.73) were found among the five dental classes. Longissimus muscle color, USDA marbling score, hot carcass weight, adjusted fat thickness, longissimus muscle area, and USDA yield grade did not differ among the five dental classes. A significant dental classification x sex interaction indicated that heifers advanced in skeletal and overall maturity at a much faster rate than steers. An increase of intramuscular fat was associated (P < 0.05) with decreased shear force (r = -0.31), whereas darkening of the lean (r = 0.16), advancing lean maturity (r = 0.21), and increased evaporative cooking loss (r = 0.39) were associated (P < 0.05) with increased shear force values. Warner-Bratzler shear force measurements were not related to sensory panel overall tenderness scores. Carcass traits accounted for a relatively small proportion of the variation in tenderness of longissimus steaks, and dental classification was not related to tenderness.

A comparison of the USDA ossification-based maturity system to a system based on dentition.

Two studies using commercially fed cattle were conducted to determine the relationship of the USDA bone ossification-based maturity system to one based on the number of permanent incisors present at slaughter. These studies showed that 91.5 to 100% of cattle with zero permanent incisors (< 23.8 mo of age), 89.1 to 97.5% of cattle with two permanent incisors (23.8 to 30.4 mo of age), 75 to 82.2% of cattle with four permanent incisors (30.4 to 38.0 mo of age), 64 to 72.5% of cattle with six permanent incisors (38.0 to 45.3 mo of age), and 40% of cattle with eight permanent incisors (> 45.3 mo of age) were graded as A maturity by the USDA maturity classification system. Kappa tests revealed no statistical relationship between the dentition- and skeletal ossification-based maturity systems. Dentition-based maturity agreed with ossification/lean maturity for only 162 of 1,264 carcasses in Exp. 1 and only 54 of 200 carcasses in Exp. 2. Cattle with two, four, six, or eight permanent incisors were classified in more youthful categories of USDA bone ossification/lean maturity than they should have been. Male cattle were more likely to be misclassified into a younger age category by the USDA system than were female cattle. It seems that determining physiological maturity by number of permanent incisors rather than by the current USDA method of subjectively evaluating skeletal and lean maturity may prove to be a more accurate technique of sorting beef carcasses into less-variable age groups.

Efficacy of intradermal vaccination.

Intradermal (ID) inoculation has been investigated as a means of vaccinating laboratory animals, domestic farm animals, and humans. Various forms of viral, bacterial, parasitic, and fungal antigens have been administered ID, with varying results. This review emphasizes results from studies reporting clinically relevant outcomes such as clinical protection and body weight change following experimental challenge. Antibody titers, cytokines, cellular responses are included as supportive data. Based on the reports reviewed, ID vaccination is a promising alternative to more traditional routes of vaccination. ID vaccination has particular appeal to the beef cattle industry based on recently emphasized quality assurance issues. It is evident that the ultimate test of vaccine efficacy is the ability to protect against clinical disease under natural challenge conditions. We propose that the immune response of ID vaccinated cattle, using clinically relevant outcomes such as morbidity, mortality, average daily gain and feed efficiency, needs to be further investigated to define the value of this potentially effective and practical means of antigen delivery, particularly for domesticated farm animals.

Lameness in feedlot cattle.

This article examines the various causes of lameness in feedlot cattle, with an emphasis on clinical signs, treatment, and prevention. Specific conditions are discussed, including interdigital necrobacillosis, laminitis, feedlot injuries, and feedlot lameness associated with Mycoplasma bovis. Immune management of the foot is also reviewed.

Association between changes in eating and drinking behaviors and respiratory tract disease in newly arrived calves at a feedlot.

OBJECTIVE: To investigate eating and drinking behaviors and their association with bovine respiratory disease complex (BRDC) and to evaluate methods of diagnosing BRDC. ANIMALS: 170 newly arrived calves at a feedlot. PROCEDURE: Eating and drinking behaviors of calves were recorded at a feedlot. Calves with clinical signs of BRDC were removed from their pen and classified retrospectively as sick or not sick on the basis of results of physical and hematologic examinations. Pulmonary lesions of all calves were assessed at slaughter. RESULTS: Calves that were sick had significantly greater frequency and duration of drinking 4 to 5 days after arrival than calves that were not sick. Sick calves had significantly lower frequency and duration of eating and drinking 11 to 27 days after arrival but had significantly greater frequency of eating 28 to 57 days after arrival than calves that were not sick. Calves at slaughter that had a higher percentage of lung tissue with pneumonic lesions had significantly lower frequency and duration of eating 11 to 27 days after arrival but had significantly higher frequency and duration of eating 28 to 57 days after arrival. Agreement for calves being sick and having severe pulmonary lesions at slaughter was adequate. Agreement for calves being removed and having pulmonary lesions at slaughter was low. CONCLUSIONS AND CLINICAL RELEVANCE: Eating and drinking behaviors were associated with signs of BRDC, but there was not an obvious predictive association between signs of BRDC in calves and eating and drinking behaviors. Fair to poor agreement was observed between antemortem and postmortem disease classification.

Lesions and effects of location for administration of clostridial bacterin-toxoid vaccines on growth performance and eating and drinking behaviors in newly arrived calves at a feedlot.

OBJECTIVES: To determine the effect of location for administration of clostridial vaccines on behavior, growth performance, and health of calves at a feedlot, the relative risk of calves developing an injection-site reaction or being misdiagnosed as having bovine respiratory disease complex (BRDC), and the percentage of subcutaneous injection-site reactions that were detectable on carcasses after the hides were removed. ANIMAL: 170 newly arrived calves at a feedlot. PROCEDURE: Eating and drinking behaviors of calves during the initial 57 days after arrival were observed at a commercial feedlot, using an electronic monitoring system. Calves were assigned randomly to receive a clostridial vaccine (base of ear or neck). Data on reactions at the injection site were collected. RESULTS: Mean daily gain (MDG) for the initial 57 days did not differ significantly between treatments. Risk of being misdiagnosed as having BRDC was not associated with location for administration of vaccine. Calves vaccinated in the base of the ear were at higher risk of having an injection-site reaction at day 57 or at slaughter. Eighty-nine percent (95% confidence interval, 52 to 100%) of injection-site reactions in the neck could not be located on the carcasses after hides were removed. Calves vaccinated in the neck drank significantly fewer times per day during the first 57 days than calves vaccinated in the base of the ear. CONCLUSIONS AND CLINICAL RELEVANCE: Location for administration of a clostridial vaccine did not significantly affect health, growth performance, or eating behavior. Most subcutaneous injection-site reactions were not detectable after the hide was removed.

Antibody titers against bovine coronavirus and shedding of the virus via the respiratory tract in feedlot cattle.

OBJECTIVE: To describe patterns of seroconversion to bovine coronavirus (BCV) and shedding of BCV from the respiratory tract in feedlot cattle. ANIMALS: 1,074 calves in feedlots in Ohio, Texas, and Nebraska. PROCEDURE: Nasal swab specimens were obtained at time of arrival (day 0) and at various times during the initial 28 days after arrival at feedlots. Specimens were tested for BCV, using an antigen-capture ELISA. Serum samples were obtained at time of arrival and again 28 days after arrival; sera were analyzed for antibodies to BCV, using an antibody-detection ELISA. RESULTS: Samples from 12 groups of cattle entering 7 feedlots during a 3-year period revealed that 78 of 1,074 (7.3%) cattle were shedding BCV (range, 0 to 35.9% within specific groups). At time of arrival, 508 of 814 (62.4%) cattle had low (< 50) or undetectable BCV antibody titers. Seroconversion to BCV during the initial 28 days after arrival was detected in 473 of 814 (58%) cattle tested (range, 20.3 to 84.1 % within specific groups). In cattle shedding BCV from the nasal passages, 49 of 68 (72.1 %) seroconverted, and 472 of 746 (63.3%) cattle that were not shedding the virus seroconverted. CONCLUSIONS AND CLINICAL RELEVANCE: Bovine coronavirus can be detected in populations of feedlot cattle in the form of viral shedding as well as seroconversion to the virus. Although only a few cattle were shedding the virus at the time of arrival at a feedlot, most of the cattle seroconverted to BCV by 28 days after arrival.

Association between infection of the respiratory tract attributable to bovine coronavirus and health and growth performance of cattle in feedlots.

OBJECTIVE: To determine the association between respiratory tract infection with bovine coronavirus (BCV), treatment for respiratory tract disease, pulmonary lesions at slaughter, and average daily gain in cattle in feedlots. ANIMALS: 837 calves in feedlots in Ohio and Texas. PROCEDURE: Nasal swab specimens were obtained from cattle at arrival in a feedlot (day 0) and at various times during the initial 28 days after arrival. Specimens were tested for BCV, using an antigen-capture ELISA. Serum samples were obtained at arrival and again 28 days after arrival and tested for antibodies to BCV, using an antibody-detection ELISA. Information was collected regarding treatment for cattle with respiratory tract disease and average daily gain during the feeding period. Pulmonary lesions were evaluated at slaughter. RESULTS: Cattle shedding BCV from the nasal cavity and developing an antibody response against BCV were 1.6 times more likely to require treatment for respiratory tract disease than cattle that did not shed the virus or develop an immune response against BCV. Additionally, cattle that shed BCV from the nasal cavity were 2.2 times more likely to have pulmonary lesions at slaughter than cattle that did not shed the virus. The BCV shedding or seroconversion status did not affect average daily gain. CONCLUSIONS AND CLINICAL RELEVANCE: Bovine coronavirus infects feedlot cattle and is associated with an increased risk for cattle developing respiratory tract disease and pulmonary lesions. Development of appropriate control measures could help reduce the incidence of respiratory tract disease.

Interaction of cattle health/immunity and nutrition.

The usual means of assessing the health of newly received beef cattle susceptible to bovine respiratory disease (BRD) are subjective, typically involving visual evaluation aided by minimal clinical measurements. Recent evidence based on the occurrence of pneumonic lung lesions at slaughter indicates a need for more accurate methods of diagnosing BRD. Inadequate passive immune transfer at birth may be an important risk factor in susceptibility to BRD, suggesting the need for management to improve passive transfer success rates. Preweaning management and vaccination practices offer opportunities for beef cattle producers to improve the immune status of newly weaned calves and decrease postweaning BRD. Feeding diets with higher levels of concentrate typically improves performance by newly weaned or received cattle, as does feeding diets supplemented with protein; however, limited data suggest that increasing concentrate and protein in receiving diets increases the rate and severity of subjectively determined BRD morbidity. Research with receiving diet concentrate/protein level relative to humoral and cell-mediated immune function coupled with indicators of health and performance is needed. Supplemental B vitamins are sometimes useful in receiving diets, but the effects have been variable, presumably reflecting differences in stress and associated feed intake responses. Vitamin E added to receiving diets to supply > or = 400 IU/animal daily seems beneficial for increasing gain and decreasing BRD morbidity; however, further dose titration experiments are needed. Supplemental Zn, Cu, Se, and Cr can alter immune function of newly received calves, and some field trials have shown decreases in BRD morbidity rate with supplementation; however, several experiments have shown no performance or health/immune benefits from supplementation of these trace minerals. Formulation of receiving diets should take into account decreased feed intake by highly stressed, newly received beef cattle and known nutrient deficiencies, but fortification of such diets with trace minerals beyond the levels needed to compensate for these effects is difficult to justify from present data.

Immunology and prevention of infection in feedlot cattle.

This article reviews the basic types of immunity, the factors relevant to feedlot cattle that have been shown to suppress immune function, and what is known about the basis of protective acquired immunity against the common bovine respiratory pathogens. The characteristics and efficacy of vaccines for respiratory disease pathogens are also reviewed. Recommendations for optimizing vaccination are presented.

Clinical trial design in feedlots.

As mentioned at the outset, the ultimate test of a product or procedure must be under field conditions and is best obtained from controlled studies of field use. Economic justification for use is based on this information. Each producer places a different value on attributable benefits such as improved health or growth performance. These values also change with fluctuating market values of cattle and feed. This makes determining the cost-benefit ratio of any procedure or product a moving target. Addressing this issue requires the clinically relevant and statistically significant differences that practitioners should be able to generate if they follow the guidelines presented here. There already exists a number of unusable studies. We suggest that those interested in undertaking this challenge be uncompromising in their experimental design. To be reliable, studies must follow the recommendations outlined above. Without sound field trial design and execution which ensures that the information is reliable and statistical significance which ensures that the differences are real, clinical outcomes cannot be extrapolated to economic justification. Any other course leads to making less than optimal recommendations on product use because of a lack of clinically relevant information.

Economic consequences of tobacco use for the Department of Defense, 1995.

This study used Centers for Disease Control and Prevention methodology to analyze the costs of smoking-attributable mortality and morbidity within the Department of Defense (DoD) based on health care costs, characteristics of the beneficiary population, and disease characteristics. Direct health care costs attributed to smoking were estimated at $584 million. Smoking-attributable disease accounted for 16% of the deaths as well as approximately 10% of all hospital bed days and 1.5% of all active duty hospitalizations. Lost productivity among active duty personnel for hospitalization and smoke breaks was valued at $346 million. A significant portion of DoD health care resources is spent caring for smoking-attributable disease, which is preventable. This report reinforces the benefits possible from the new emphasis on wellness promotion within the DoD. Efforts are needed to prevent the initiation of smoking and encourage smoking cessation in order to reduce health care costs and increase the probability for long and healthy lives for DoD beneficiaries.

Advances in pulmonary immunology.

Advances in pulmonary immunology often begin with better understanding of the mechanisms of pulmonary defenses. This leads to new technologies or better use of existing technologies to prevent pneumonia. These can be validated in challenge models, but ultimately, advances in pulmonary immunology come from demonstration that a management strategy reduces the burden of disease in a production setting. This can be difficult, and may require team efforts from producers, allied industry, and academia. Each team member brings a unique perspective and set of resources to the endeavor. The alternative is to use immunoenhancing management strategies based on extrapolation and faith.

Effect of booster vaccination with a multivalent clostridial bacterin-toxoid on sudden death syndrome mortality rate among feedlot cattle.

OBJECTIVE: To determine whether booster vaccination with a multivalent clostridial bacterin-toxoid would affect the sudden death syndrome (SDS) mortality rate among feedlot cattle. DESIGN: Field trial. ANIMALS: 83, 115 cattle at a Nebraska feedlot. PROCEDURE: Cattle arriving at the feedlot underwent routine processing according to established protocol. All cattle received a sequentially numbered ear tag and a 2-ml dose of a multivalent bacterin-toxoid designed to protect cattle against Clostridium chauvoei, C speticum, C novyi, C sordellii, and C perfringens types C and D. Approximately 90 days prior to slaughter, growth promotants were implanted in all cattle, and cattle were allocated to a treatment or control group on the basis of the last digits of their ear tag numbers. Cattle in the treatment group received a second 2-ml dose of clostridial bacterintoxoid; control cattle did not. RESULTS: Significant differences between groups in regard to crude, feeding pen, or SDS mortality rates were not detected. Sudden death syndrome mortality rate across both groups was 0.24%. If the SDS mortality rate in midwestern feedlot cattle was reduced > or = 40% by booster vaccination with a multivalent clostridial bacterin-toxoid, this experiment included enough animals to have a 90% probability of detecting that difference. CLINICAL IMPLICATIONS: Booster vaccination with a multivalent clostridial bacterin-toxoid does not affect SDS mortality rate among feedlot cattle.

Use of a newly developed rapid microbial ATP bioluminescence assay to detect microbial contamination on poultry carcasses.

A newly developed rapid microbial ATP bioluminescence test (R-mATP) was shown to be an adequate means to assay the microbial load of poultry carcasses. This assay utilizes differential extraction and filtration to separate somatic from microbial ATP in a very rapid timeframe. The assay requires approximately 5 min to complete; approximately 3.5 min to sample and 90 s analytical time. Correlation coefficient (r) between aerobic colony counts and R-mATP test results (n=329) was 0.82. Post-test probabilities to correctly classify carcasses with different levels of microbial contamination were as high as 98% for samples of > or = 3.5 log aerobic CFU per ml. Given the rapidity of this assay, the R-mATP holds potential for monitoring the microbial load of carcasses at poultry-processing critical control points. Other potential applications of this new version of the microbial ATP bioluminescence test are discussed.

Relationships among treatment for respiratory tract disease, pulmonary lesions evident at slaughter, and rate of weight gain in feedlot cattle.

OBJECTIVE: To quantify the effects of treatment for clinical respiratory tract disease and pulmonary lesions identified at slaughter on rate of weight gain in feedlot cattle. DESIGN: Prospective longitudinal study. ANIMALS: 469 feedlot steers. PROCEDURE: Clinical respiratory tract disease was monitored between birth and slaughter. Steers were weaned at approximately 6 months old and entered into the feedlot for a mean of 273 days. Mean daily weight gain (MDG) was monitored during the feeding period. Lungs were collected at slaughter and evaluated for gross lesions indicative of active or resolved pneumonia. RESULTS: Mean daily weight gain during the feeding period was 1.30 kg, and ranged from 1.16 to 1.46 kg within individual pens. Thirty-five percent of steers received treatment for respiratory tract disease between birth and slaughter, whereas 72% had pulmonary lesions evident at slaughter. Among steers treated for clinical respiratory tract disease, 78% had pulmonary lesions, whereas 68% of untreated steers had pulmonary lesions. Pulmonary lesions at slaughter were associated (P < 0.01) with a 0.076-kg reduction in MDG during the feeding period. Treatment for clinical disease was not associated with MDG after adjustment for the effect of pulmonary lesions. CLINICAL IMPLICATIONS: Treatment of clinically affected feedlot cattle may be inadequate to prevent significant production losses attributable to respiratory tract disease.

Haptoglobin response to clinical respiratory tract disease in feedlot cattle.

OBJECTIVE: To quantify haptoglobin response to respiratory tract disease in feedlot cattle, and to investigate its ability to predict disease outcome and response to antibiotic treatment. DESIGN: Randomized clinical trial. ANIMALS: 60 feedlot calves with clinical respiratory tract disease. PROCEDURE: Calves were randomly assigned to receive a standard antibiotic treatment regimen (TRT), or to observation pens without antibiotic treatment. Serum haptoglobin concentration was measured at initial and final examinations. Calves were examined for presence of gross pulmonary lesions at slaughter. RESULTS: Mean +/- SD serum haptoglobin concentration at initial examination was 67 +/- 108 mg/dl, with range of 0 to 508 mg/dl. Haptoglobin concentration at initial examination was similar for the TRT group and the group that did not receive antibiotic treatment, but at final examination, TRT-group calves had lower (P < 0.01) mean values. Calves receiving antibiotic treatment had haptoglobin concentration at or near zero at final examination. Calves not receiving antibiotic treatment had only slightly lower mean haptoglobin concentration at final examination, compared with initial examination. Within treatment groups, haptoglobin concentration was similar for cases with different outcomes. Calves with gross pulmonary lesions at slaughter had numerically higher, although statistically similar, haptoglobin concentrations at initial examination, compared with calves without lesions. CONCLUSIONS: Feedlot cattle with clinical respiratory tract disease have a large and variable haptoglobin response. Antibiotic treatment resulted in lower serum haptoglobin values, although low values were not required for full clinical recovery. CLINICAL RELEVANCE: Serum haptoglobin concentration may be an indicator of response to antibiotic therapy, although it appears to be unrelated to case severity or need for treatment.

Serum haptoglobin concentrations in a population of feedlot cattle.

OBJECTIVE: To determine serum haptoglobin concentrations in a population of feedlot cattle and evaluate their usefulness in predicting subsequent clinical respiratory tract disease. DESIGN: Prospective longitudinal study. ANIMALS: 366 beef calves. PROCEDURE: Serum samples were obtained at feedlot entry and 40 and 65 days on feed (DOF). Calves were observed daily for clinical signs of respiratory tract disease. The lungs of 144 of the calves were evaluated at slaughter for the presence of gross lesions of pneumonia. RESULTS: 58% of the calves had detectable serum haptoglobin concentration in at least 1 sample. The proportion of calves with detectable haptoglobin were similar at each sample collection time. A higher proportion of the calves had values > 10 mg/dl at 40 DOF. The proportion of calves observed with clinical disease during the 10-day period after the 40 DOF sample increased (P < 0.10) as serum haptoglobin concentration increased. At 65 DOF, calves with serum haptoglobin value > 10 mg/dl had a higher (P < 0.05) rate of subsequent clinical respiratory tract disease than did calves with lower values. The proportion of calves with gross pulmonary lesions slaughter increased (P < 0.05) from 39% among calves without detectable serum haptoglobin concentration in any of the 3 samples to 63% among calves with at least 1 observed value > 10 mg/dl. CONCLUSIONS: We observed associations between serum haptoglobin concentration and subsequent clinical respiratory tract disease and pulmonary lesions at slaughter. However, serum haptoglobin concentration alone is not adequate for prediction of clinical disease. CLINICAL RELEVANCE: The usefulness for cross-sectional sampling of serum haptoglobin concentration as a diagnostic tool for clinical respiratory tract disease in feedlot cattle appears to be limited.

Effects of various risk factors on plasma protein and serum immunoglobulin concentrations of calves at postpartum hours 10 and 24.

In an attempt to identify important predictors of failure of passive immunoglobulin transfer (< 800 mg of IgG/dl), identify calves with failure of passive immunoglobulin transfer, and determine the effects of a colostrum supplement, blood samples were collected from 263 calves at postpartum hours 10 and 24. Calves of dams diagnosed with mastitis had lower mean plasma protein and IgG concentrations at 10 (P < 0.05) and 24 (P < 0.01) hours. Plasma protein and IgG concentrations were similar for single and twin calves at 10 hours, but IgG concentration at 24 hours was higher (P < 0.01) in twin calves. Calves born to dams that had dystocia had numerically lower mean plasma protein and IgG concentrations than did calves born to dams that had normal delivery. However, observed differences were small and, after adjustment for other important factors, these differences were not significant. Age of dam was associated with plasma protein (P < 0.05) and IgG (P < 0.10) concentrations at 10 hours, but had no effect at 24 hours. Plasma protein and IgG concentrations decreased as calves were born later in the calving season, although the association of birth date with IgG concentration at 24 hours was marginal (P = 0.07). Calf sex, dam body condition score, and birth weight were not related to plasma protein or IgG values. The sensitivity and specificity of a cutoff value of 4.8 g of protein/dl of plasma, measured at 10 hours, for diagnosing failure of passive immunoglobulin transfer at 10 hours were 78 and 94%, and for diagnosing failure of passive immunoglobulin transfer at 24 hours were 88 and 73%, respectively. A colostrum supplement administered to calves with low plasma protein concentration at 10 hours had no effect on plasma protein or IgG values at 24 hours or on preweaning morbidity and mortality.

Passive immune status at postpartum hour 24 and long-term health and performance of calves.

We quantified the effect of passive immune status on pre- and postweaning health and growth performance of calves raised in a beef production environment. Blood samples were collected at postpartum hour 24 from 263 crossbred calves for determination of plasma protein (PP) and serum IgG concentrations. Serum IgG concentration was classified as adequate (> 1,600 mg/dl), marginal (800 to 1,600 mg/dl), or inadequate (< 800 mg/dl). Plasma protein concentration was classified as adequate (> or = 4.8 g/dl) or inadequate (< 4.8 g/dl). Morbidity and mortality events in the study population were monitored from birth to weaning, and after weaning throughout the feeding period. The lowest concentrations of serum IgG and PP were observed among calves that experienced morbidity or mortality prior to weaning. Calves that experienced morbidity in the feedlot had lower 24-hour PP values, but had IgG concentration similar to that in calves that were not observed to be ill during the feeding period. Calves classified as having inadequate IgG concentration were at greater risk of preweaning mortality (odds ratio [OR] = 5.4), neonatal morbidity (OR = 6.4), and preweaning morbidity (OR = 3.2), compared with calves classified as having adequate IgG concentration at 24 hours. Calves classified as having inadequate PP concentration at 24 hours had a greater risk of morbidity (OR = 3.0) and respiratory tract morbidity (OR = 3.1) while in the feedlot, compared with calves classified as having adequate PP concentration. The effects of 24-hour passive immune status on calf growth were indirect through effects on morbidity outcomes.(ABSTRACT TRUNCATED AT 250 WORDS)