North American Beef Research Articles

Unraveling the microbial diversity of bovine liver abscesses: isolation, identification, and genomic characterization of the Bacteroides found in hepatic lesions.

Liver abscesses (LAs) are commonly found in cattle raised in feedlots and result from a bacterial infection of the liver. Not only are LAs a concern for animal health, but they also impact growth efficiency, animal welfare, and cost the North American beef industry upwards of $120 million per annum. Recently, it has been found that 25%-50% of liver abscess microbiomes have prominent levels of Bacteroides; however, to date, the biological relevance in LA pathogenesis and the identity of these bacteria are unknown. This research describes the isolation, identification, and genomic characterization of the Bacteroides found in bovine liver abscesses. These data provide a critical foundation for expanding our knowledge of the potential role Bacteroides play in liver abscess development and could contribute to the identification of novel targets for developing treatments to prevent this important production-limiting disease.

Caring for calves: Canadian public perspectives of calf handling methods during spring processing

In North American beef production, handling and restraint of young calves is integral to animal welfare and management practices. This study used a mixed-method approach to gather public perceptions of three handling and restraint methods common in western Canada during spring processing (TT—tilt table, RW—roping and wrestling, and NF—roping and NordFork). Canadians (n = 551) participated in an online survey that included videos of each handling method to ascertain preferences and acceptability. Participants were given industry information about handling and restraint or generic information regarding hay as a control information statement within the topic of agriculture. The survey also collected information about knowledge of the beef industry, animal welfare, and empathy toward animals. The reasons for preferences for specific handling methods were described as the presence of a perceived positive attribute and the absence of a perceived negative for most preferred methods, and inversely when explaining the least preferred method. The main themes focused on the calf’s experience, perception of handler actions, and pragmatic balancing of needs for a good life for the calf. All methods were rated as more acceptable for participants that ate meat consistently, knew more about the beef industry, and, to a lesser extent, if the individual had a lower animal empathy score. Acceptability was not affected by providing information about the practices; however, information did elicit more pragmatic reasoning. Most participants preferred TT over NF and RW (p < 0.001) and found TT more acceptable as well (p < 0.001). The TT was the most preferred method due to calf experience and human handling—notably the absence of dragging a calf, which was predominant in why participants selected NF or RW as their least preferred method. Consistency of themes highlights that regardless of method or acceptability, the fundamental expectation of the public focuses on the perception of the calf’s quality of life, humane handling, and pragmatism, which are values aligned with beef sustainability initiatives.

A mixed method approach to analysing patterns and drivers of antibiotic use and resistance in beef farms in Argentina.

Antimicrobial resistance is a challenge to be faced by all livestock sectors; within beef farming, antibiotic use patterns vary by country and management practices. Argentina is a country with high beef production & consumption but limited information surrounding antibiotic use. The aims of this project was to understand how antibiotics are being used across the beef industry in Argentina and exploring drivers of usage. Quantitative and qualitative data was collected by: A survey of breeding and feedlot farms including antibiotic use (from purchase data); a detailed analysis of two feedlot farms' therapeutic antibiotic use records; a survey of vets' views on certain antibiotic practices; and a focus group of farmers and vets focusing on wider influences affecting decision making. Antibiotic use data was calculated using mg/population corrected unit (PCU) (ESVAC) and thematic analysis was used to identify drivers of antibiotic use among participants. The median use across 17 farms that supplied purchase data was 76.52 mg/kg PCU (ESVAC; IQR = 36.81 mg/kg PCU [ESVAC]). The detailed farm records showed that the largest reason for treatment was group treatments (72.92% of treatments) followed by treatment for respiratory disease (12.75% of treatments). Macrolides accounted for 76.37% of treatments. Nearly half of farms used routine prophylactic treatment for arriving animals (n = 7/18). The use of quarantine and 'sick pens' were seen as important by surveyed vets with antibiotic prophylaxis and in-feed antibiotics seen as contributors to antibiotic resistance. The focus group highlighted the influence of the economic and political landscape on husbandry practices and the responsibility the farming sector had towards antibiotic stewardship. Overall, Argentine beef feedlots resemble North American beef feedlots in terms of antibiotic practices but with considerably lower usage, with in-feed monensin representing a large proportion of total ABU. The adaptation period presents a challenge to animal health; antibiotics are administered a prophylaxis, metaphylactic and individual treatments depending on farm management practices. Further research into internationally comparable measures of ABU and detailed cost-benefit analysis of practical, on-farm interventions are needed to aid improved antimicrobial stewardship in livestock systems globally.

334 Metagenomic- and culture-based characterization of the ocular microbiome in cattle with infectious bovine keratoconjunctivitis

Abstract Pinkeye, clinically known as infectious bovine keratoconjunctivitis (IBK), is one of the most highly contagious diseases impacting cattle at all ages. Despite extensive use of antibiotics and vaccines targeting Moraxella bovis, the primary IBK pathogen, the incidence of pinkeye has been increasing in North American beef cow-calf operations. This highlights the incomplete understanding of the pathogenesis of this disease and the need for novel and alternative approaches to control IBK. The objectives of this study were to: 1) characterize the ocular microbiome of beef cattle with and without IBK using shotgun metagenomic sequencing; 2) investigate the genetic diversity of M. bovis, Moraxella bovoculi, and commensal ocular bacterial isolates; 3) evaluate whether selected ocular probiotic candidate strains inhibit Moraxella pathogen growth in the presence of the ocular microbiome in culture using qPCR. A total of 143 ocular swabs were collected from cattle with (n = 102) or without IBK (n = 42) and before antibiotic treatment from beef herds across North Dakota, USA. Fifty samples from IBK (n = 38) and healthy cattle (n = 12) were also subjected to shotgun metagenomic sequencing. Seven bacterial species were relatively more abundant (P < 0.05) in the healthy cattle ocular microbiome including Bifidobacterium globosum, Bacillus licheniformis, Pasteurella multocida, Ruminococcus sp900316555, and Ruminococcus sp900100595. Arthrobacter luteus was the only bacterial species significantly associated with IBK-affected cattle. From the metagenomes, 37 high-quality dereplicated metagenome-assembled genomes (MAGs) were recovered, nearly a third of which were identified as Mesomycoplasma bovoculi (n = 10). M. bovis (n = 5) and M. bovoculi (n = 13) were also isolated from the ocular swabs of both healthy and IBK-affected cattle. These isolates represented 9 M. bovoculi and 5 M. bovis strains (average nucleotide identity < 99.99%). We also isolated and sequenced several potentially beneficial bacterial species from healthy cattle including Bacillus pumilus, Lactiplantibacillus plantarum, Lentilactobacillus buchneri, Levilactobacillus brevis, and Weizmannia coagulans. Four of these probiotic candidates were also tested for their inhibitory effects against M. bovoculi in co-culture with the ocular microbiome after 24 h incubation using qPCR. The B. pumilus, L. buchneri, L. plantarum, and W. coagulans strains, as well as a mixture of all four isolates, significantly reduced the growth of Moraxella. In summary, our results provide important information on the culturable and non-culturable fraction of the bovine ocular microbiome potentially associated with IBK and suggest that certain bacterial species in the eye may inhibit the growth of Moraxella spp.

263 Public perspectives of calf handling: A survey of Canadians

Abstract In North American beef production handling and restraint of young calves is integral to animal welfare and management practices. This study used a mixed method approach to gather public perceptions of three handling and restraint methods common on beef operations in western Canada (RW - Roping and Wrestling, NF – roping and NordForks, and TT – Tilt Table). Canadian participants (n = 551) recruited by CloudResearch to represent the national demographics participated in an online survey that included videos of each handling method to ascertain preferences and acceptability. Prior to watching the videos, participants were given industry information about handling and restraint or generic information regarding hay as a control information statement within the topic of agriculture. The survey also collected information about knowledge of the beef industry, animal welfare, and empathy toward animals. The reasons for preferences were described as presence of a perceived positive attribute and absence of a perceived negative for most preferred methods, and inversely when explaining least preferred method. The findings focused on calf’s experience, perception of handler actions, and pragmatic balancing of handler needs and a good life for the calf. Methods were rated as more acceptable for participants that ate meat consistently, knew more about the beef industry, and, to a lesser extent, if the individual had a lower animal empathy score (Table 1). Acceptability was not affected by providing information about the practices; however, information about handling and restraint did elicit more pragmatic reasoning. Most participants preferred TT over NF and RW (P < 0.001) and found TT more acceptable as well (P < 0.001). The TT was the most preferred method due to calf experience and human handling, notably the absence of dragging a calf, which was predominant in why participants selected NF or RW as their least preferred method. Consistency of themes highlights that the Canadian public has a fundamental expectation of value for the quality of life of the calf, humane handling, and pragmatism which aligns with beef sustainability initiatives and represent points of connection for building trust between industry and the public.

The impact of commingling preconditioned calves on mortality, morbidity and performance in a feedlot

Bovine respiratory disease (BRD) is the most important disease in the North American beef industry, causing substantial eco­nomic losses due to morbidity and mortality, including treat­ments, reduced performance, and increased antimicrobial use. Preconditioning (PC) to mitigate BRD was proposed as early as 1967 and constitutes management practices that reduce stressors and optimize resilience through vaccination against bacterial and viral pathogens, optimized timing of dehorning, castration, best weaning strategy, and training calves to eat from a bunk and drink from a water source at least 45 d before transport to the feedlot. Despite proven profits for precondi­tioning of beef calves, PC hasn’t been established in the current beef industry. Besides the lack of premiums paid, there is also the question if commingling of PC and auction-derived (AD) calves in the feedlot can hamper PC calves’ expected growth and health advantages. Therefore, our objective was to evalu­ate the impact of optimally preconditioned calves on mortality, morbidity and average daily gain (ADG) during the first 40 days in the feedlot when PC calves where commingled with different proportions of AD calves (25, 50, 75%).

A Single Intranasal Dose of Bacterial Therapeutics to Calves Confers Longitudinal Modulation of the Nasopharyngeal Microbiota: a Pilot Study.

To address the emergence of antimicrobial-resistant pathogens in livestock, microbiome-based strategies are increasingly being sought to reduce antimicrobial use. Here, we describe the effects of intranasal application of bacterial therapeutics (BTs) on the bovine respiratory microbiota and used structural equation modeling to investigate the causal networks after BT application. Beef cattle received (i) an intranasal cocktail of previously characterized BT strains, (ii) an injection of metaphylactic antimicrobial (tulathromycin), or (iii) intranasal saline. Despite being transient colonizers, inoculated BT strains induced longitudinal modulation of the nasopharyngeal bacterial microbiota while showing no adverse effect on animal health. The BT-mediated changes in bacteria included reduced diversity and richness and strengthened cooperative and competitive interactions. In contrast, tulathromycin increased bacterial diversity and antibiotic resistance and disrupted bacterial interactions. Overall, a single intranasal dose of BTs can modulate the bovine respiratory microbiota, highlighting that microbiome-based strategies have potential in being utilized to mitigate bovine respiratory disease in feedlot cattle. IMPORTANCE Bovine respiratory disease (BRD) remains the most significant health challenge affecting the North American beef cattle industry and results in $3 billion in economic losses yearly. Current BRD control strategies mainly rely on antibiotics, with metaphylaxis commonly employed to mitigate BRD incidence in commercial feedlots. However, the emergence of multidrug-resistant BRD pathogens threatens to reduce the efficacy of antimicrobials. Here, we investigated the potential use of novel bacterial therapeutics (BTs) to modulate the nasopharyngeal microbiota in beef calves, which are commonly administered metaphylactic antibiotics to mitigate BRD when sourced from auction markets. By direct comparison of the BTs with an antibiotic commonly used for BRD metaphylaxis in feedlots, this study conveyed the potential use of the BTs to modulate respiratory microbiome and thereby improve resistance against BRD in feedlot cattle.

North American Beef Breeding and the Modernization of the International Cattle Breeding Industries, 1950–2000

Abstract This article deals with transformations in beef cattle breeding practices in North America from 1950 to 2000, and the implication of these changes across the Western world. It was a period of profound adjustment for beef cattle breeders, involving battles over genetic defects, the importation of new breeds, changing standards in relation to husbandry, and the extension of quantitative genetic breeding practices. These innovations would be echoed across Europe in the production of beef cattle and would also interact with the way dairy cattle were bred. This article explains the upheaval in beef breeding between 1950 and 2000, as well as how that upheaval affected dairy cattle breeding. Changes in beef breeding, in effect, modified the functioning of the entire cattle breeding world.

PSXI-8 Heritability estimates of antibody- and cell-mediated immune response in north American angus beef cattle

Abstract Including immune response traits in breeding programs has been suggested as a solution to improve overall animal health and enhance disease resistance but is not yet available for Angus cattle in North America. One way to measure immune response is to use the High Immune Response (HIR™) technology, which identifies animals with superior heritable immunity by evaluating antibody-mediated (AMIR) and cell-mediated (CMIR) immune response, allowing for the calculation of an estimated breeding value for total adaptive immune response for each animal. Before HIR™ can be included in beef cattle breeding programs, genetic parameters, including heritability, must be estimated for the traits involved. The objective of this study was to estimate a preliminary heritability for AMIR and CMIR in North American Angus beef cattle. On day 0 of the phenotyping protocol, cattle were immunized intramuscularly with a preparation of type 1 (CMIR) and type 2 (AMIR) antigens with adjuvant. On day 14, cattle received an intradermal injection of 0.1 mL of the CMIR test antigen in the right tail fold, and 0.1 mL PBS in the left tail fold. Change in cutaneous double skinfold thickness after 24 hours was used to assess CMIR. Blood was collected on days 0 and 14 to evaluate serum antibody to the type 2 antigen by ELISA to quantify AMIR. Heritability estimates were calculated for Canada and the USA separately, and then for both countries combined using single-trait animal models in ASReml and are presented in Table 1. The results of this study indicate that the heritabilities of AMIR and CMIR are moderate and emphasize the potential for its inclusion into Angus breeding schemes.

Antimicrobial resistance in Mannheimia haemolytica: prevalence and impact.

Bovine respiratory disease (BRD) is the most common cause of morbidity and mortality in North American beef cattle. In recent years, isolation of strains of Mannheimia haemolytica that are resistant to multiple different classes of antimicrobials has become commonplace. New research would suggest that the routine use of antimicrobials by some cattle operations might be driving emerging resistance patterns, with the majority of the spread observed due to propagation of strains of M. haemolytica that have acquired integrative conjugative elements. To date, there is little information evaluating the impact of antimicrobial resistance on clinical outcome in cattle with BRD.

Greenhouse gas and ammonia emissions from stored manure from beef cattle supplemented 3-nitrooxypropanol and monensin to reduce enteric methane emissions

The investigative material 3-nitrooxypropanol (3-NOP) can reduce enteric methane emissions from beef cattle. North American beef cattle are often supplemented the drug monensin to improve feed digestibility. Residual and confounding effects of these additives on manure greenhouse gas (GHG) emissions are unknown. This research tested whether manure carbon and nitrogen, and GHG and ammonia emissions, differed from cattle fed a typical finishing diet and 3-NOP [125–200 mg kg−1 dry matter (DM) feed], or both 3-NOP (125–200 mg kg−1 DM) and monensin (33 mg kg−1 DM) together, compared to a control (no supplements) when manure was stockpiled or composted for 202 days. Consistent with other studies, cumulative GHGs (except nitrous oxide) and ammonia emissions were higher from composted compared to stockpiled manure (all P < 0.01). Dry matter, total carbon and total nitrogen mass balance estimates, and cumulative GHG and ammonia emissions, from stored manure were not affected by 3-NOP or monensin. During the current experiment, supplementing beef cattle with 3-NOP did not significantly affect manure GHG or NH3 emissions during storage under the tested management conditions, suggesting supplementing cattle with 3-NOP does not have residual effects on manure decomposition as estimated using total carbon and nitrogen losses and GHG emissions.

Finishing Cattle in All-Natural and Conventional Production Systems

Beef cattle producers in the North America have a variety of production and marketing options and must choose the best production system for their situation. This review describes considerations involved in choosing between feeding cattle conventionally versus feeding them in programs that prohibit the use of certain technologies. Data from peer-reviewed journals, extension publications, nutritional consultants, governmental organizations, and feed companies were used to construct this review. Most cattle in North America are fed in conventional production systems. Conventional beef production systems typically use steroidal implants, ionophores, and beta-adrenergic agonists to improve animal productivity; as well as feed grade and injectable antimicrobials to control, treat or prevent disease and improve animal health. These technologies have been shown to lower the cost of production, allowing for beef to be competitive in the global protein market. Some consumers have expressed a preference for beef produced without these technologies. These “All-natural” (AN) cattle may bring a premium price in the market. The economic impact of differing productions systems can be described in relation to 1) cost of production, 2) operating costs of the feedlot, 3) price paid for feeder calves, and 4) price received for fed cattle. Conventional production provides the most favorable outcome for factors 1, 2, and 3, while AN production provides the most favorable outcome for item 4. There are also industry wide and societal aspects related to differing beef production systems related to health and safety of beef, land use, and cost of production allowing for a greater share of the global protein market. Technologies used in conventional production are critical tools to North American beef production. Differences in efficiencies between each type of non-conventional production systems must be re-captured in added premiums when cattle are marketed and sold. Premiums for AN cattle are enticing, but the true differences in the cost of production between the AN and conventional cattle must be evaluated in order for a producer to make the correct decision for their operation.

Systematic review and meta-analysis comparing arrival versus delayed vaccination of high-risk beef cattle with 5-way modified-live viral vaccines against BHV-1, BRSV, PI3, and BVD types 1 and 2

Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in North American beef cattle, and thus a major economic and welfare concern of individuals involved in the beef cattle industry. The most common viruses implicated in BRD are Bovine Herpesvirus 1 (BHV-1), Bovine Respiratory Syncytial Virus (BRSV), Parainfluenza 3 (PI3), and Bovine Viral Diarrhea Viruses types 1 and 2 (BVD 1 and 2), and it is common practice to administer vaccines against these viruses to cattle entering feedlots and stocker operations at arrival. However, there have long been concerns that cattle may not mount an optimal immune response when vaccinated at this time. A number of studies have been conducted to evaluate the effects of vaccination timing on morbidity and mortality, but often include other interventions that might confound interpretation of the results. This can make an objective evaluation of the effects of only vaccination timing difficult. It is therefore our goal to provide a systematic review of these studies, and extract relevant data to perform a meta-analysis of vaccine timing on BRD morbidity, retreatment rate, and mortality.

Characterization of cell mediated immune responses in stressed and unstressed beef calves

Bovine respiratory disease (BRD) is the most common cause of morbidity and mortality in North American beef cattle. One part of the cattle industry that is particularly affected by BRD is the stocker cattle segment. It is common for stocker calves to be vaccinated against the most common disease causing agents at arrival to stocker facilities. Unfortunately, stocker calves experience numerous stressors that could impact the efficacy of vaccination and it has been established that stress can suppress immune function in cattle. The objectives of this study were to characterize the cell-mediate immune responses multiple source, highly commingled calves of unknown health history and compare the responses of these calves to those of calves that were single source, of a known health history, and weaned for 60 days.

Prevalence of multi drug antimicrobial resistance in Mannheimia haemolytico isolated from high-risk Stocker cattle at arrival and two weeks after processing

Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in North American beef cattle. Mannheimia haemolytica (Mh) is the bacterial pathogen most frequently isolated from cattle with BRD and the prevalence of antimicrobial resistance in this pathogen has been increasing. Administration of antimicrobials to prevent BRD is commonplace in stocker cattle. Our objectives were to determine the prevalence of Mh isolated from the nasopharynx of high-risk stocker cattle at arrival and at resampling 10 to 14 days later, and second, to determine the prevalence of antimicrobial resistant Mh at these same time points.

Prevalence of multi drug antimicrobial resistance in Mannheimia haemolytica isolated from high-risk stocker cattle at arrival and two weeks after processing1

Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in North American beef cattle. () is the bacterial pathogen most frequently isolated from cattle with BRD and the prevalence of antimicrobial resistance in this pathogen has been increasing. Administration of antimicrobials to prevent BRD is commonplace in stocker cattle, but the impact of this practice on emergence of resistance in is unknown. High risk, sale barn origin bull and steer calves ( = 169) were transported to a stocker facility in central Georgia and sampled via deep nasopharyngeal swab (NPS) at arrival processing. All calves received the macrolide antimicrobial tulathromycin (2.5 mg/kg subcutaneously) at arrival processing. A second NPS was collected from each calf 10 to 14 d after arrival. The occasional calves diagnosed and treated for BRD prior to 10 to 14 d were swabbed and cultured prior to treatment. Swabs were submitted for culture and antimicrobial susceptibility testing using the Kirby-Bauer disk diffusion method. Of the 169 cattle enrolled, 27 (16.0%) were culture positive for at arrival processing and of these, a multi-drug resistant (MDR) strain of was detected in 1 (3.7%). In contrast, 123 (72.8%) cattle were culture positive for at second sampling and of these, a MDR strain of was detected in 122 (99.2%). The proportions of cattle culture positive for and positive for MDR at arrival processing and at second sampling were significantly different ( < 0.001). At the level of the individual bacterial isolate, 366 individual isolates were collected from the calves at the time of the second sampling. Of these isolates, 361 (98.6%) were intermediate or resistant to all macrolides tested (tilmicosin, gamithromycin, tulathromycin) and the fluoroquinolone enrofloxacin. In addition, 254 isolates (69.4%) were intermediate or resistant to florfenicol and 4 (1.1%) were intermediate or resistant to ceftiofur. There was a significant difference in the proportion of isolates resistant to all of the drug classes except cephalosporins at arrival processing versus second sampling ( < 0.001). Our results show that there was an increase in the proportion of calves positive for from arrival processing to second sampling, and that there was an increase in the proportion of calves that had MDR strains of detected from arrival processing to second sampling. More research is needed to understand the role of metaphylaxis on MDR in and the impact of MDR on morbidity and mortality in stocker cattle.

The sickness response in steers with induced bovine respiratory disease before and after treatment with a non-steroidal anti-inflammatory drug

The sickness response in steers with induced bovine respiratory disease before and after treatment with a non-steroidal anti-inflammatory drug

Developing an early warning system for bovine respiratory disease

DESPITE decades of research, controlling bovine respiratory disease (BRD) remains one of the hardest challenges in practice (Fulton and Confer 2012). Although the infectious agents, risk factors and immunological responses...

Short Communication: Tenderness of suckler beef produced in British Columbia

Hartling, I., Cinel, B., Donkor, K. K., Ross Friedman, C., Paetkau, M. J. and Church, J. S. 2014. Short Communication: Tenderness of suckler beef produced in British Columbia. Can. J. Anim. Sci. 94: 295–298. In order to investigate the potential of suckler beef production in British Columbia, shear force values were determined using Warner–Bratzler shear (WBS) force tests on 10 major muscles obtained from suckler-raised Simmental cattle along with the longissimus thoracis from grain- and grass-fed cattle of similar breeding. Shear force values obtained for suckler beef were then compared with literature values from grain-fed beef. All suckler beef muscles except the psoas major and spinalis dorsi had lower WBS values than their grain-fed counterparts from literature values, while the longissimus thoracis was shown to have equal tenderness in all three production systems. Results suggest that a higher number of muscles from suckler beef in this study could be used as steaks than is typically observed in the North American beef industry.

Effects of mild and pasteurizing heat treatments on survival of generic and verotoxigenic Escherichia coli from beef enrichment cultures

Effects of mild and pasteurizing heat treatments on survival of generic and verotoxigenic Escherichia coli from beef enrichment cultures