Browsing by Author "Hales, K. E. (TTU)"

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Effects of backgrounding-phase rate of gain on performance and carcass characteristics of feedlot steers
(2022) Blom, E. J.; Gentry, W. W.; Pritchard, R. H.; Hales, K. E. (TTU)
Objective: The objective was to evaluate effects of varying backgrounding-phase growth rates (BGR) on subsequent finishing-phase performance and carcass characteristics of feedlot cattle. Materials and Methods: Steers (n = 144) were randomly assigned to 1 of 3 BGR treatments from study initiation to 409 kg of BW. Treatments consisted of 0.91 kg/d (0.91ADG), 1.13 kg/d (1.13ADG), or 1.36 kg/d (1.36ADG). Net energy equations were used to prescribe sufficient DM to achieve desired BGR for each group. When each treatment reached the target BW of 408 kg at the end of the backgrounding phase, steers were transitioned to a finishing diet. From this point on, treatments were managed similarly. Steers within each treatment were slaughtered independently at a common 12th-rib fat endpoint. Results and Discussion: Backgrounding-phase ADG linearly increased (P < 0.01). The backgrounding phase lasted 76, 61, and 54 d for 0.91ADG, 1.13ADG, and 1.36ADG, respectively. Finishing-phase ADG and DMI linearly decreased (P ≤ 0.02) as BGR increased, with no difference in G:F (P ≥ 0.16). Cumulative ADG linearly increased with greater BGR (P = 0.02), and G:F also increased (P = 0.07). Restricting BGR linearly increased hot carcass weight (P = 0.04). Marbling score tended to respond quadratically to increasing BGR as it increased from 0.91ADG to 1.13ADG and then decreased between 1.13ADG and 1.36ADG (P = 0.05). Marbling scores responded quadratically (P = 0.05). Implications and Applications: Using a low BGR can result in improved finishing-phase performance and greater final BW; however, a greater number of days on feed is required. Increases in hot carcass weight also can be achieved with lesser BGR, although greatest carcass quality may be realized with only modest restriction in BGR.
Effects of changes in finishing diets and growth technologies on animal growth performance and the carbon footprint of cattle feeding: 1990 to 2020
(2022) Crawford, D. M.; Hales, K. E. (TTU); Smock, T. M. (TTU); Cole, N. A.; Samuelson, K. L.
Objective: Our objective was to estimate the effects of changes in feedlot diets and the availability of performance-enhancing technologies on growth performance and the carbon footprint of cattle feeding between 1990 and 2020. Materials and Methods: A model was developed to represent feedlot diets and technologies used in 1990 versus 2020 and evaluate changes in growth performance and carbon footprint. Byproduct feeds became more common between 1990 and 2020; thus, corn and dry roughage inclusion rates decreased. Estradiol-only implants and monensin were the available technologies in 1990, whereas in 2020 use of implants with combinations of trenbolone acetate and estradiol, monensin, and ractopamine hydrochloride (in the final 28 to 42 d) were common. Results and Discussion: In both 1990 and 2020 use of all available technologies increased final BW, ADG, G:F, and hot carcass weight compared with no technology. From 1990 to 2020 initial BW, final BW, ADG, G:F, hot carcass weight, and daily DMI increased. Total days on feed increased by 44 d from 1990 to 2020. Compared with no technology, use of technologies in both 1990 and 2020 decreased total greenhouse gas emissions per animal (CO2 equivalent, CO2e). Because cattle had greater days on feed in 2020, all sources of greenhouse gas emissions per animal increased compared with the values estimated in 1990. However, when expressed as CO2e/kg of BW gain, emissions have decreased by 4.4% because of greater total BW gain in 2020 versus 1990. Implications and Applications: Feedlot cattle decreased relative emissions from 4.78 kg of CO2e/kg of BW gain in 1990 to 4.58 kg of CO2e/kg of BW gain in 2020. Overall, feedlots in 2020 produced 47.5% more BW gain with 1.4% less cattle, while only increasing total CO2e by 39.5%. Therefore, changes in available technologies and diet formulations have improved efficiency and reduced the carbon footprint of feedlot cattle production in the past 30 yr.
Effects of increasing the concentration of neutral detergent fiber in roughage and bulk density of steam-flaked corn on growth performance, carcass characteristics, and liver abscesses of finishing beef steers fed diets without tylosin phosphate*†
(2024) McDaniel, Z. S. (TTU); Galyean, M. L. (TTU); Broadway, P. R.; Carroll, J. A.; Sanchez, N. C.Burdick; Hanratty, A. N. (TTU); Dornbach, C. W. (TTU); Line, D. J. (TTU); Smock, T. M. (TTU); Manahan, J. L. (TTU); Hales, K. E. (TTU)
Objective: We evaluated the effects of dietary NDF concentration from alfalfa hay and bulk density of steam- flaked corn (SFC) on growth performance, carcass characteristics, and liver abscesses in finishing beef steers. Materials and Methods: Crossbred beef steers (n = 214; 60 pens; initial BW = 417 ± 11.9 kg) were blocked by BW and assigned randomly to treatments and fed an average of 112 d. The treatments were arranged as a 2 × 3 factorial with 10 pens per treatment and consisted of 3 NDF concentrations from alfalfa hay (3%, 4.5%, or 6%) and 309 g/L (24 lb/bu) or 412 g/L (32 lb/bu) SFC (69% or 33% starch availability, respectively). Growth performance and carcass data were analyzed with PROC MIXED of SAS with pen as the experimental unit. Quality grades and liver scores were analyzed as binomial proportions using PROC GLIMMIX. Contrast statements were used to separate linear and quadratic effects of increasing roughage NDF. Results and Discussion: Dry matter intake responded quadratically from d 0 to 35 as roughage NDF increased from 3% to 6%, and DMI increased linearly as roughage NDF increased on d 70 to 105 and d 0 to final. Otherwise, no differences in growth performance were noted. Marbling score responded quadratically to roughage level and was greater for steers fed 3% than for those fed 4.5% or 6% roughage NDF. Steers fed 309 g/L SFC tended to have a larger LM area than those fed 412 g/L SFC. The total percentage of abscessed livers at slaughter decreased linearly as roughage NDF was increased from 3% to 6% of DM as did the presence of A+ abscesses. In addition, total liver abscesses were 13.9 percentage points less in steers fed 412 versus 309 g/L SFC. Implications and Applications: Results suggest that increasing roughage NDF and bulk density of SFC are dietary strategies that can decrease the presence of liver abscesses at slaughter without negatively affecting growth performance.
Infrared thermography as an alternative technique for measuring body temperature in cattle1
(2023) Hoffman, A. A. (TTU); Long, N. S. (TTU); Carroll, J. A.; Sanchez, N. C.Burdick; Broadway, P. R.; Richeson, J. T.; Jackson, T. C.; Hales, K. E. (TTU)
Objective: The objective of the current experiment was to evaluate the use of infrared thermography (INFRA) as an alternative to rectal temperature (RT) for monitoring body temperature in steers. Materials and Methods: An Escherichia coli lipo- polysaccharide (LPS) was administered to 31 steers (initial BW 295.8 ± 46.5 kg) via i.v. injection to produce a febrile response. Each steer was fitted with an indwelling rectal probe to monitor changes in RT in 30-min intervals. Thermal temperatures (INFRA) were collected in 30-min increments beginning at h 0.5 to 1.5, h 2.5 to 3.5, and h 4.5 to 5.5. Additionally, temperatures were collected in 60-min increments beginning at h −1.5 to −0.5 and h 6.5 to 12.5. Relative to LPS administration, thermal temperatures were subsequently recorded at h 18.5, 24.5, 36.5, and 47.5. Correlation analyses were conducted using PROC CORR where Pearson and Spearman correlation coefficients were evaluated between the RT and INFRA. Additionally, RT and INFRA were analyzed using PROC MIXED where the model included temperature measure- ment method (RT or INFRA), hour, and the interaction of method × hour. Steer within temperature measurement method was included as a random effect and was the sub- ject of the repeated measures analysis. Results and Discussion: Increases in RT and INFRA were evident within 1 h of the LPS administration, both methods confirming an induced febrile response. Rectal temperature and INFRA did not differ for 50% of the time points (P ≥ 0.16); however, the 2 methods differed at h −0.5, 0.5, 1.5, 5.5, 9.5, 10.5, 11.5, 18.5, 24.5, 36.5, and 47.5 (P < 0.01). Temperatures between each method diverged 9.5 h after LPS was given. A Pearson correlation of 0.71 (P < 0.01) was noted between RT and temperature of the eye measured using INFRA. Likewise, a Spearman correla- tion of 0.66 (P < 0.01) was noted between RT and INFRA measurements. Infrared imaging is noninvasive, quick to perform, and decreases additional stressors caused by han- dling and restraint of the animal. Implications and Applications: These data suggest that further research is necessary for INFRA to be a viable alternative to RT measurements in cattle.
Liver abscesses—New perspectives on a historic fed-cattle issue
(2024) Broadway, P. R.; Nagaraja, T. G.; Lawrence, T. E.; Galyean, M. L. (TTU); Hales, K. E. (TTU)
Purpose: Our purpose was to provide commentary and new perspectives related to liver abscesses, a historic problem in beef cattle, by describing and discussing docu- mented research, anecdotal observations, and opinions re- garding the causation, detection, and prevention of liver abscesses. Sources: Sources for this article include peer-reviewed, scientific literature; abstracts; proceedings; theses and dissertations; popular press articles; personal communica- tions; and unpublished research data. Synthesis: Liver abscess (LA) disease in cattle is a multifactorial, polymicrobial disease that has wide-rang- ing effects on productivity and profitability throughout all stages of the beef production cycle. The interest in and the study of LA has drastically increased in the past several years, driven largely by efforts to identify alterna- tives to the use of antibiotics for LA control. Although a primary, prevailing theory on LA formation has existed for decades, recent research has led to alternative theo- ries as well as new questions about the role of breed-type specific management, behavior, feed intake patterns, and other factors on LA causation. The inability to detect LA before slaughter complicates research evaluating mitiga- tion strategies and disease etiology. Moreover, the inability to detect LA in live cattle has hindered researcher efforts to understand timing of abscess development or whether an abscess can resolve. Conclusions and Applications: Although the prima- ry pathogens associated with LA have been identified, an effective mitigation strategy has eluded researchers. None- theless, new perspectives and research efforts are needed from both basic and applied perspectives using multidis- ciplinary, collaborative approaches to successfully combat the challenges faced by the beef industry related to LA.
Random metaphylaxis effects on health outcomes, complete blood count, antimicrobial use, and growth performance of high-risk beef steers
(2023) Hanratty, A. N. (TTU); Sanchez, N. C.Burdick; Broadway, P. R.; Carroll, J. A.; Hoffman, A. A. (TTU); Manahan, J. L. (TTU); McDaniel, Z. S. (TTU); Smock, T. M. (TTU); Dornbach, C. W. (TTU); Line, D. J. (TTU); Theurer, M. E.; Galyean, M. L. (TTU); Hales, K. E. (TTU)
Objective: Our objectives were to evaluate the effects of random metaphylaxis administered at feedlot arrival to 0, 33, 66, or 100% of high-risk beef cattle on clinical health, growth performance, complete blood cell counts, and antimicrobial use during a 35-d receiving period. Materials and Methods: Crossbred beef steers (n = 216; arrival BW = 197 ± 6.4 kg) were used in a general- ized complete block design consisting of 2 source blocks, each with 4 BW blocks, and 4 treatments. Experimen- tal treatments and steers were randomly assigned to pen within source block: (1) negative control, s.c. injection with sterile saline (0M); (2) 33% of steers per pen giv- en metaphylaxis at random with tildipirosin (33M); (3) 66% of steers per pen given metaphylaxis at random with tildipirosin (66M); and (4) positive control; conventional metaphylaxis given to 100% of steers with tildipirosin (100M). Body weight and blood samples for quantification of complete blood count were collected on d 0, 14, and 35. Metaphylactic treatment was included in the model as a fixed effect, and BW block within source block was included as a random effect. Results and Discussion: The percentage of steers treated with an antimicrobial for bovine respiratory dis- ease once was greater (P < 0.01) for 0M and 33M than for 66M and 100M. Neither BW on d 35 nor ADG from d 0 to 35 differed among treatments (P ≥ 0.65), but DMI and DMI as a percentage of BW from d 0 to 35 was greater (P ≤ 0.03) for 66M and 100M than for 0M and 33M. No dif- ferences in hematological variables were detected among treatments (P ≥ 0.19), whereas most complete blood count variables were affected by day (P < 0.01). Most notably, the neutrophil:lymphocyte ratio was greater (P < 0.01) on d 0 than on d 14 and 35. Implications and Applications: These data suggest that arrival metaphylaxis can be randomly administered to 66% of cattle without increasing bovine respiratory dis- ease morbidity, while simultaneously increasing DMI simi- lar to conventional metaphylaxis. Random metaphylaxis to 66% of steers at arrival decreased antimicrobial use for metaphylaxis while simultaneously maintaining health outcomes and growth performance of high-risk beef cattle.
Review: Summary of the Special Issue on liver abscesses in cattle and thoughts on future research*
(2024) Hales, K. E. (TTU)
Objective: My objective was to summarize 16 original research manuscripts and 1 perspectives and commentary contribution that were submitted, peer reviewed, and ac- cepted in this Special Issue on liver abscesses in cattle. Materials and Methods: A summary of key points made in the Special Issue articles is provided. Additional conclusions and thoughts about future directions of re- search to address liver abscesses (LA) in cattle are offered. Results and Discussion: This Special Issue represents the current understanding of the etiology, blood chemis- try biomarkers, dietary and management strategies, and mitigation strategies for LA in cattle used in the feedlot industry throughout the United States and Canada. Sev- enteen articles from researchers and industry professionals studying LA in cattle are included, with studies ranging from practical dietary intervention strategies to experi- ments designed to understand the mode of action and the etiology of LA development. Implications and Applications: Liver abscess disease is a multifactorial, polymicrobial disease that affects mul- tiple organ systems within the body, reflecting complex interactions among the host, environment, and pathogens. The pathogenesis of this disease needs to be further exam- ined, and basic and applied research approaches should be employed to advance our understanding of liver abscesses in cattle.
Use of a novel direct-fed microbial as an alternative for tylosin phosphate to control liver abscesses and decrease antimicrobial use in finishing beef steers
(2024) Hoffman, A. A. (TTU); Fernando, S. C.; Wells, J. E.; Woerner, D. R. (TTU); Manahan, J. L. (TTU); Long, N. S. (TTU); McDaniel, Z. S. (TTU); Smock, T. M. (TTU); Carroll, J. A.; Sanchez, N. C.Burdick; Broadway, P. R.; Hales, K. E. (TTU)
Objective: Our goal was to evaluate the use of a novel direct-fed microbial as an alternative to antimicrobials to decrease liver abscesses in finishing beef cattle. Materials and Methods: Beef steers (n = 240; initial BW = 263 ± 18.0 kg) were used in a randomized complete block design comprising 3 BW blocks and 3 pen replications per treatment during the receiving period and 3 BW blocks and 14 to 15 pen replications per treatment during the finishing phase. Experimental treatments were assigned randomly to pen within BW block and consisted of (1) negative control, dietary supplement with no tylosin phosphate; (2) positive control, dietary supplement formulated to supply 90 mg of tylosin phosphate daily (Tylan-100; Elanco Animal Health); (3) positive control with tylosin phosphate removed the last 65 d of the feeding period; and (4) novel direct-fed microbial Bacillus licheniformis fed daily at 1 × 1011 cfu/steer. Results and Discussion: From d 0 to 59, ADG, DMI, DMI as a percentage of BW, and G:F did not differ. During the finishing period, live- and carcass-adjusted final BW did not differ among treatments. Likewise, in the finishing period, there were no differences in ADG, DMI, DMI as a percentage of BW, or G:F. No differences in hot carcass weight, DP, marbling score, longissimus dorsi area, 12th-rib fat thickness, or calculated yield grade were detected among dietary treatments. Liver abscess incidence and severity were not affected by dietary treatments. Implications and Applications: The use of a novel direct-fed microbial, B. licheniformis, in beef cattle fed in small research pens did not affect growth performance, carcass characteristics, or liver abscess prevalence or severity. Bacillus licheniformis is not a viable strategy to decrease liver abscesses in growing and finishing beef cattle.