February 2025
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4 Reads
Applied Animal Science
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February 2025
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4 Reads
Applied Animal Science
October 2024
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58 Reads
Animals
Predictions of microbial crude protein (MCP) synthesis for beef cattle generally rely on empirical regression equations, with intakes of energy and protein as key variables. Using a database from published literature, we developed new equations based on the intake of organic matter (OM) and intakes or concentrations of crude protein (CP) and neutral detergent fiber (NDF). We compared these new equations to several extant equations based on intakes of total digestible nutrients (TDN) and CP. Regression fit statistics were evaluated using both resampling and sampling from a simulated multivariate normal population. Newly developed equations yielded similar fit statistics to extant equations, but the root mean square error of prediction averaged 155 g (28.7% of the mean MCP of 540.7 g/d) across all equations, indicating considerable variation in predictions. A simple approach of calculating MCP as 10% of the TDN intake yielded MCP estimates and fit statistics that were similar to more complicated equations. Adding a classification code to account for unique dietary characteristics did not have significant effects. Because MCP synthesis is measured indirectly, most often using surgically altered animals, literature estimates are relatively few and highly variable. A random sample of individual studies from our literature database indicated a standard deviation for MCP synthesis that averaged 19.1% of the observed mean, likely contributing to imprecision in the MCP predictions. Research to develop additional MCP estimates across various diets and production situations is needed, with a focus on developing consistent and reliable methodologies for MCP measurements. The use of new meta-omics tools might improve the accuracy and precision of MCP predictions, but further research will be needed to assess the utility of such tools.
September 2024
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14 Reads
Journal of Animal Science
Liver abscesses (LA) continue to be an economic challenge for the beef industry. Chronic ruminal acidosis and ruminitis contribute to LA development. Fusobacterium necrophorum subsp. necrophorum, a ruminal bacterium, is the primary causative agent. Damaged ruminal, and possibly other gut regions, become susceptible to invasion and colonization by subsp. necrophorum, which reaches the liver via portal blood to cause abscesses. We hypothesize that the LA occurrence is related to the presence and concentrations of subsp. necrophorum in gut contents and epithelial tissues. Our primary objective was to detect, isolate and quantify subsp. necrophorum in gut contents and tissues in steers with experimentally induced LA. An experimental model, which included ruminal acidosis followed by intraruminal inoculation of subsp. necrophorum alone or with Salmonella enterica serotype Lubbock, was used to assess the relationship. Steers (n = 61) from three independent studies with three treatment groups were used. Treatments included: 1) forage-based diet with intraruminal inoculation of subsp. necrophorum; 2) ruminal acidosis with intraruminal inoculation of subsp. necrophorum; and 3) ruminal acidosis with intraruminal inoculation of subsp. necrophorum and S. Lubbock. Steers were euthanized 3 wk after bacterial inoculation and liver, gut contents, and tissue samples (ruminal, ileal and colonic) from steers with LA (n = 27) and with healthy livers (n = 34) were collected and subjected to culture method and quantitative PCR to isolate, detect, and quantify subsp. necrophorum. Data were analyzed by PROC GLIMMIX of SAS after summarizing frequency of isolation in various sample types within each study for steers with and without LA and converted to a binomial proportion. Concentrations were analyzed using steer as the experimental unit. The model included the fixed effect of liver status (abscessed or not) and study as the random effect. The frequency of isolation and mean concentration of subsp. necrophorum in purulent materials of LA were 100% and 3.5 x 107 Log10 CFU/g, respectively. The frequency of isolation of subsp. necrophorum from ruminal tissues of steers with LA was greater than steers with healthy livers (35.4 vs 14.5%; P = 0.04). Likewise, the concentration of subsp. necrophorum in ruminal tissues was greater in steers with LA than with healthy livers (4.2 vs 3.6 Log10 CFU/g; P < 0.001). None of the ileal and colonic tissues, except one ileal tissue in each group, yielded subsp. necrophorum. The concentrations of subsp. necrophorum in ruminal, ileal, and colonic contents did not differ (P = 0.9) between steers with LA or with healthy livers. Our data suggest that the occurrence of LA is positively related to prevalence and concentration of subsp. necrophorum in ruminal tissue, and the colonization likely serves as a source of continuous flow of bacterial emboli into the portal blood to initiate LA development.
September 2024
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11 Reads
Journal of Animal Science
We evaluated the association of diet type, ruminal acidosis bout frequency, and intraruminal bacterial inoculum concentration on liver abscess (LA) development in steers. Beef × dairy steers [n = 40, initial body weight (BW) = 107 ± 11 kg] were assigned randomly to 1 of 5 treatments that included either a high-dose (HD; 1 × 109 and 1 × 109 CFU/mL) or a low-dose (LD; 1 × 106 and 1 × 106 CFU/mL) of Fusobacterium necrophorum subsp. necrophorum and Salmonella enterica serovar Lubbock, respectively. Treatments included: NCON = high-forage diet with no intraruminal inoculation; CON+HD = high-forage diet with a single, HD inoculation; 2AD+HD = 2 acidotic diet cycles with a single, HD inoculation; 4AD+3LD = 4 acidotic diet cycles with a series of 3 LD inoculations; and 4AD+HD = 4 acidotic diet cycles with a single, HD inoculation. Individual animal was the experimental unit. Continuous data were analyzed using mixed models, and categorical data were analyzed as binomial proportions with treatment, time, and their interactions as the fixed effects. Hematology was evaluated before harvest on d 21 to evaluate indications of systemic disease. Although no difference was observed in rumenitis among treatments (P = 0.79), steers with LA presented with 8 percentage points greater rumenitis than steers without LA. Steers consuming the high-forage diet also presented with rumenitis. Prevalence of LA was 0, 37.5, 37.5, 50, and 12.5% for NCON, CON+HD, 2AD+HD, 4AD+3LD, and 4AD+HD, respectively (P = 0.68). A key observation of this study was that steers fed a high-forage diet presented with LA when dosed with of F. necrophorum and S. enterica, even in the absence of the acidotic diet.
September 2024
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5 Reads
Journal of Animal Science
Our objective was to evaluate hematological measurements that could be indicative of liver abscesses (LA) in weaned beef × dairy cross steers. Beef × dairy cross steers [n = 40; initial body weight (BW) = 120 ± 12 kg] were sourced from a local dairy calf ranch and transported 166 km to the USDA-ARS Livestock Issues Research Unit Liberty Farm near Lubbock, TX (d -16). Calves were initially housed outside in soil-surfaced pens for 16 d with ad libitum access to water and high-forage receiving diet before being moved into individual pens within an environmentally controlled barn (d 0). While housed in the barn, calves were cycled between a high-forage diet (2 d) and a high-concentrate finishing diet (3 d) for 3 cycles. Additionally, calves were administered Fusobacterium necrophorum subsp. necrophorum (4.25 x 106 CFU in 100 mL) and Salmonella enterica serotype Lubbock (1.29 x 106 CFU in 100 mL) intraruminally on d 0, 5, and 10. Following the last inoculation on d 10, calves were fed the high concentrate finishing diet for the remainder of the study. Whole blood samples for measurement of complete blood counts were collected via jugular venipuncture on d 0, 10, 21 and 30. On d 31, calves were harvested to determine LA prevalence. Fifty percent of calves developed at least one LA. Complete blood count analysis revealed day effects (P ≤ 0.03) for all variables, with the exception of basophil percentage (P = 0.06; Table 1). Prevalence of a liver abscess was associated with increased (P < 0.01) neutrophil count, neutrophil:lymphocyte ratio, and neutrophil percentage, concomitant with decreased (P ≤ 0.04) lymphocyte percentage, and monocyte percentage. Additionally, a tendency (P = 0.09) was observed for decreased red blood cells in calves with a LA compared with those without. These data suggest that changes in neutrophil and lymphocyte concentrations within the blood may be indicative of LA prevalence in beef × dairy steer calves and hold potential as predictive markers for LA.
September 2024
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12 Reads
Journal of Animal Science
Our objective was to longitudinally assess the presence and quantity of Salmonella enterica throughout the gastrointestinal tract of finishing beef steers with and without liver abscesses (LA). Crossbred steers [n = 225; initial body weight (BW) = 353 ± 39 kg] were used in an observational case-control design with individual steer designated as the experimental unit. Nasal, ruminal fluid, and fecal samples were collected at feedlot arrival, 1 wk after adaptation to the finishing diet, and the day before harvest at a commercial abattoir. Healthy and abscessed liver tissue samples were collected at harvest. Steers were fed a steam-flaked corn-based diet without tylosin phosphate. After harvest, LA prevalence was determined, and steers were sorted into those with and without LA. Data were analyzed using the GLIMMIX procedure of SAS. Overall, LA prevalence was 18.7% (n = 42). Nasal Salmonella prevalence was 34.4% but did not differ between steers with or without LA (P = 0.73), and nasal Salmonella concentrations did not differ between treatments (P = 0.85) or collection day (P = 0.50). Ruminal fluid Salmonella prevalence was 73.7% but did not differ between treatments (P = 0.83). From feedlot arrival to harvest, ruminal fluid Salmonella concentration and prevalence decreased (P < 0.01). Fecal Salmonella prevalence tended (P = 0.09) to be 6.4% greater in steers with LA. Conversely, fecal Salmonella concentration tended (P = 0.07) to be 5.9% greater in steers without LA. Fecal Salmonella prevalence was greatest after transition to the finishing diet (P < 0.01), whereas fecal Salmonella concentration was greatest before harvest (P < 0.01). Liver Salmonella prevalence was 9.8% and 6.5% for steers with and without LA, respectively, but did not differ between treatments (P = 0.47). Similarly, liver Salmonella concentrations did not differ in steers with or without LA (P = 0.18). Overall, these data suggest Salmonella concentration and prevalence were affected by time on feed, but not indicative of LA formation.
June 2024
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7 Reads
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2 Citations
Applied Animal Science
June 2024
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4 Reads
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4 Citations
Applied Animal Science
June 2024
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19 Reads
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1 Citation
Applied Animal Science
March 2024
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47 Reads
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3 Citations
Journal of Animal Science
Holstein steers (n = 40; initial BW = 84.9 ± 7.1 kg) were used to study the genesis of liver abscesses (LA) using an acidotic diet challenge with or without intraruminal bacterial inoculation. Steers were housed in individual pens inside a barn and randomly assigned to one of three treatments: (1) low-starch control diet comprised primarily of dry-rolled corn and wet corn gluten feed (CON); (2) high-starch acidotic diet with steam-flaked corn (AD); or (3) acidotic diet plus intraruminal inoculation with Fusobacterium necrophorum subsp. necrophorum (9.8 × 108 colony forming units [CFU]/mL), Trueperella pyogenes (3.91 × 109 CFU/mL), and Salmonella enterica serovar Lubbock (3.07 × 108 CFU/mL), previously isolated from LA (ADB). Steers in AD and ADB were fed the acidotic diet for 3 d followed by 2 d of the CON diet, and this cycle was repeated four times. On day 23, ADB steers were intraruminally inoculated with the bacteria. At necropsy, gross pathology of livers, lungs, rumens, and colons was noted. Continuous data were analyzed via mixed models as repeated measures over time with individual steer as the experimental unit. Mixed models were also used to determine the difference in prevalence of necropsy scores among treatments. Ruminal pH decreased in AD and ADB steers during each acidotic diet cycle (P ≤ 0.05). LA prevalence was 42.9% (6 of 14) in ADB vs. 0% in AD or CON treatments (P < 0.01). Ruminal damage was 51.1% greater in ADB than in AD (P ≤ 0.04). Culture of LA determined that 100% of the abscesses contained F. necrophorum subsp. necrophorum, 0% contained T. pyogenes, 50% contained Salmonella, and 50% contained a combination of F. necrophorum subsp. necrophorum and Salmonella. The F. necrophorum subsp. necrophorum was clonally identical to the strain used for the bacterial inoculation based on phylogenetic analysis of the whole genome. This experimental model successfully induced rumenitis and LA in Holstein steers and confirms the central dogma of LA pathogenesis that acidosis and rumenitis lead to the entry of F. necrophorum into the liver to cause abscesses. Our findings suggest that an acidotic diet, in conjunction with intraruminal bacterial inoculation, is a viable model to induce LA. Further research is needed to determine the repeatability of this model, and a major application of the model will be in evaluations of novel interventions to prevent LA.
... Specifically, an increase in the F:B ratio in the small intestine likely stems from an increased need for Firmicutes to digest a high energy ration. Liver abscesses in cattle occur most commonly due to bacterial translocation from the gut into the hepatic portal circulation (Nagaraja and Chengappa, 1998;Broadway et al., 2024). Recent microbiome studies of liver abscesses from feedlot cattle suggest these lesions have highly polymicrobial communities (Fuerniss et al., 2022a;. ...
June 2024
Applied Animal Science
... However, there are limited options available for producers, especially under grazing conditions, and it is necessary to evaluate the profitability and life cycle assessment of each alternative (Arndt et al 2022, Vargas et al 2022. Modifying dietary characteristics through improving grazing management and precision feeding could result in more efficient fermentation, reducing the energy losses as CH 4 (Arndt et al 2022, Galyean andHales 2024). Improved manure management according to production system type and region represents a prioritized strategy for reducing manure CH 4 and N 2 O emissions, especially in confined production systems (Chadwick et Improving animal and herd efficiency through implementing practices such as increasing productive days or reproductive performance represents a strategy to reduce GHG emissions by lowering the required days and the number of animals to support the meat and dairy value chain (figures 1-3). ...
January 2024
Methane
... The inability to distinguish cattle with clinical or subclinical BRD from healthy animals results in treating the entire group with antimicrobials [2,3,12]. Most metaphylaxis research has required treating the entire cohort; however, recent information suggests targeted metaphylaxis of a portion of the pen based on physiologic parameters may have some benefits compared to no treatment [13,14]. This approach shows promise but involves additional procedures at initial cattle processing. ...
December 2023
Applied Animal Science
... Furthermore, statistically significant relationships between DMI variation and indexes of feed efficiency, such as residual feed intake (RFI), residual ADG (RADG), and residual feed intake and gain (RIG; Berry and Crowley, 2012), may provide an explanation for variation in feed efficiency between animals. Recently, Galyean and Hales (2023) proposed novel means of assessing day-to-day variation of DMI of cattle, as opposed to merely using the day-to-day CV. One of these proposed methods was the Euclidean distance (ED), which is essentially the distance between 2 data points. ...
December 2023
Applied Animal Science
... Because protein is often an expensive supplemental nutrient, inaccurate estimates of MCP synthesis have important practical consequences in ruminant feeding. Nonetheless, extant MCP prediction equations are characterized by relatively large prediction errors (20 to 30% of the observed mean [2,3]). ...
October 2023
Journal of Animal Science
... This strategy preserves the dataset's comprehensiveness and upholds its original integrity. We apply this transformation to scenarios 2 through 5. Subsequently, we apply outlier removal for all features detected using the z-score method in scenarios 2 through 5. Failure to handle these outliers may lead to suboptimal model performance, particularly for LR and KNN models, which are sensitive to outliers [36,37]. After outlier removal, the dataset contains 31,164 data points, a reduction of 4.37%. ...
January 2024
Scientia Agricola
... While high ruminal LPS levels are not necessary for translocation, a compromised epithelial barrier seems essential (Khafipour et al., 2009a, b). Similarly, exposure to pathogenic bacteria is not sufficient to produce liver abscesses (McDaniel et al., 2023). Elevated dCO 2 contributes to ruminal LPS formation (Dain et al., 1956), justifying its presence during SARA, and CO 2 holdup might disrupt the ruminal epithelium through increased epithelial irrigation and hyperosmolarity (Ash and Dobson, 1963;Thorlacius, 1972). ...
July 2023
Journal of Animal Science
... The energy density of finishing diets for feedlot systems is typically ~8.58 MJ of net energy for maintenance (NE m ) per kilogram (DM basis), but may range between 8.37 and 8.79 MJ/kg NE m (Ríos-Rincón et al. 2014). The greater proportion of fat relative to protein in weight gain during the late finishing phase (the last 40-50 days) results in lower gain efficiency (greater energy intake/kg of bodyweight gain), as fat accretion requires nearly twice as much energy as does muscle accretion (Galyean et al. 2023). Zilpaterol hydrochloride (ZH) is a β2-adrenergic agonist that stimulates protein accretion. ...
July 2023
Journal of Animal Science
... Steer DMI was not impacted (P = 0.59) by increasing DOF from 142 to 185 DOF, an additional 42 DOF (Table 2). Streeter et al. (2012) reported similar findings for large pen studies where increasing DOF did not impact DMI, in addition, Galyean et al., (2023) found that extending DOF did not impact DMI for beef heifers in a 6-study summary. These findings are contrary to Hicks et al. (1987), Pyatt et al. (2005b), Wilken et al. (2015) who reported linear increases in DMI as DOF increased for finishing cattle. ...
April 2023
Applied Animal Science
... Acosta examined adjustments made to dairy feeding patterns to lower costs and adapt to market demands; these practices directly impact digestion processes as well as subsequent methane production by cows and regional methane concentration [29]. Galyean and Hales studied how some farms increased their production efficiency and decreased their emissions through optimized pasture management techniques or by improving feeding techniques, which mitigates the negative effects of the COVID-19 pandemic [30]. ...
February 2023
Animals