MicroRNA profiles for different tissues from calves challenged with Mycoplasma bovis or challenged with Mycoplasma bovis and bovine viral diarrhea virus

The objective was to determine differences in microRNAs (miRNAs) counts in several tissues of calves challenged with Mycoplasma bovis (M. bovis) or with M. bovis and bovine viral diarrhea virus (BVDV). Eight calves approximately 2 months of age were randomly assigned to three groups: Control (CT; n = 2), M. bovis (MB; n = 3), and Coinfection (CO; n = 3). On day 0, calves in CO were intranasally challenged with BVDV and calves in MB with M. bovis. On day 6, CO calves were challenged with M. bovis. Calves were euthanized 17 days post-challenge and serum (SER), white blood cells (WBC), liver (LIV), mesenteric (MLN) and tracheal-bronchial (TBLN) lymph nodes, spleen (SPL), and thymus (THY), were collected at necropsy. MiRNAs were extracted from each tissue from each calf. Significant (P< 0.01) differences in miRNAs expression were observed in SER, LIV, MLN, TBLN, SPL, and THY. There were no significant (P> 0.05) miRNAs in WBC. In SER, the CO group had levels of miR-1343-3p significantly higher than the CT and MB groups (P = 0.0071). In LIV and SPL, the CO group had the lowest counts for all significant miRNAs compared to CT and MB. In TBLN, the CT group had the highest counts of miRNAs, compared to MB and CO, in 14 of the 21 significant miRNAs. In THY, the CO group had the highest counts, in 4 of the 6 significant miRNAs compared to CT and MB. BVDV was associated with reduction of miRNAs in LIV, SPL, MLN, and TBLN, and M. bovis reduced counts of miRNAs in only TBLN. Measuring circulating miRNAs to assess disease condition or to develop intervention strategies to minimize respiratory diseases in cattle caused by BVDV or M. bovis will be of limited use unless an alternative approach is developed to use them as indicators of disease.

Production Significance of Bovine Respiratory Disease Lesions in Slaughtered Beef Cattle

Bovine respiratory disease (BRD) is still a serious concern in feedlots, where it exerts a negative effect on farm productivity. There is a shortage of studies focused on the evaluation of BRD-associated lesions at the slaughterhouse in clinically healthy animals. The objective of this work was to investigate the prevalence and type of subclinical pneumonic lesions in slaughtered beef cattle, according to the age range and management system, and its impact on carcass weight. A total of 1101 beef cattle intended for human consumption were examined at slaughter. Information on age, sex, management system and carcass weight was recorded. The presence and type of pneumonia were evaluated according to gross and microscopic findings and etiological agents by PCR. Lung pneumonic lesions appeared in 17.9% of animals and were predominant among veal calves. According to the type, chronic catarrhal pneumonia prevailed in the majority of animals, and mixed and extensively reared cattle were more likely to suffer acute fibrinous pneumonia. The presence of pneumonic lesions was associated with a significant decrease in carcass weight that had more of an impact in veal male calves coming from intensive systems. Bacterial infections were the predominant infectious agent and the only cause of acute fibrinous pneumonia, while viruses were infrequent and only found in lesions with chronic catarrhal pneumonia. This study shows the importance of BRD in beef feedlots upon production values and points out the feasibility of slaughterhouse assessment of pneumonia as a method for the evaluation of BRD significance.

Economic effects of policy options restricting antimicrobial use for high risk cattle placed in U.S. feedlots

The rising public health threat of antimicrobial resistance, the influence of food service companies, as well as the overall lack of positive image of using medical products in intensive farming are major drivers curbing antimicrobial use. In the future, government policies may affect practices of antimicrobial use in beef production in feedlots, a prominent current user of antimicrobials in animal agriculture, but also the agricultural industry generating the highest cash receipt in the U.S. Our objective was to estimate the cost effect from the following policies in feedlots: 1) using antimicrobials for disease prevention, control, and treatment; 2) using antimicrobials only for treatment of disease; and 3) not using antimicrobials for any reason. We modelled a typical U.S. feedlot, where high risk cattle may be afflicted by diseases requiring antimicrobial therapy, namely respiratory diseases, liver abscesses and lameness. We calculated the net revenue loss under each policy of antimicrobial use restriction. With moderate disease incidence, the median net revenue loss was $66 and $96 per animal entering the feedlot, for not using antimicrobials for disease prevention and control, or not using any antimicrobials, respectively, compared to using antimicrobials for disease prevention, control, and treatment. Losses arose mainly from an increase of fatality and morbidity rates, almost doubling for respiratory diseases in the case of antimicrobial use restrictions. In the case of antimicrobial use prohibition, decreasing the feeder cattle price by 9%, or alternatively, increasing the slaughter cattle price by 6.3%, would offset the net revenue losses for the feedlot operator. If no alternatives to antimicrobial therapy for prevention, control and treatment of current infectious diseases are implemented, policies that economically incentivize adoption of non-antimicrobial prevention and control strategies for infectious diseases would be necessary to maintain animal welfare and the profitability of beef production while simultaneously curbing antimicrobial use.

Feed Intake and Weight Changes in Bos indicus-Bos taurus Crossbred Steers Following Bovine Viral Diarrhea Virus Type 1b Challenge Under Production Conditions

Bovine viral diarrhea virus (BVDV) has major impacts on beef cattle production worldwide, but the understanding of host animal genetic influence on illness is limited. This study evaluated rectal temperature, weight change and feed intake in Bos indicus crossbred steers (n = 366) that were challenged with BVDV Type 1b, and where family lines were stratified across three vaccine treatments of modified live (MLV), killed, (KV) or no vaccine (NON). Pyrexia classification based on 40.0 °C threshold following challenge and vaccine treatment were investigated for potential interactions with sire for weight change and feed intake following challenge. Pyrexia classification affected daily feed intake (ADFI, p = 0.05), and interacted with day (p < 0.001) for ADFI. Although low incidence of clinical signs was observed, there were marked reductions in average daily gain (ADG) and cumulative feed intake during the first 14 day post-challenge; ADG (CV of 104%) and feed efficiency were highly variable in the 14-day period immediately post-challenge as compared to the subsequent 14-day periods. A sire × vaccine strategy interaction affected ADFI (p < 0.001), and a sire by time period interaction affected ADG (p = 0.03) and total feed intake (p = 0.03). This study demonstrates that different coping responses may exist across genetic lines to the same pathogen, and that subclinical BVDV infection has a measurable impact on cattle production measures.

Linking disease epidemiology and livestock productivity: The case of bovine respiratory disease in France

Concerns are growing over the impact of livestock farming on environment and public health. The livestock industry is faced with the double constraint of limiting its use of natural resources and antimicrobials while ensuring its economic sustainability. In this context, reliable methods are needed to evaluate the effect of the prevention of endemic animal diseases on the productivity of livestock production systems. In this study, an epidemiological and productivity model was used to link changes in Bovine Respiratory Disease (BRD) incidence with the productivity of the beef and dairy cattle sectors in France. Cattle production parameters significantly affected by BRD were selected through literature review. Previous field study results and national cattle performance estimates were used to infer growth performances, mortality rates and carcass quality in the cattle affected and not affected by BRD. A steady-state deterministic herd production model was used to predict the productivity of the dairy and beef sector and their defined compartments (breeding-fattening, feedlot young bulls, and feedlot veal) in case of BRD incidence reduction by 20%, 50% or 100%. Results suggested that BRD should be controlled at a priority in beef breeding farms as eradication of BRD in beef calves would increase the whole beef sector's productivity by 4.7-5.5% while eradication in other production stages would result in lower productivity gain in their respective sectors. However, the analysis performed at compartment level showed that, in both the beef and dairy sector, young bull and veal feedlot enterprises derive more economic benefits from BRD eradication for their own compartment (increase in productivity of 8.7-12.8% for beef young bulls) than the breeding farms (increase in productivity of 5.1-6% for beef calves), which may limit the investments in BRD control.

Effect of bovine respiratory disease during the receiving period on steer finishing performance, efficiency, carcass characteristics, and lung scores

Bovine respiratory disease (BRD) is responsible for the majority of morbidity, mortality, and production losses occurring in feedlots. This experiment evaluated the effects of BRD incidence on subsequent finishing performance, efficiency, carcass characteristics, and lung scores of steers. Crossbred steers (n = 516) were monitored daily for clinical signs of BRD (BRD attributed morbidity and mortality were 66.5 and 13.2%, respectively). A subset of calves (n = 174) were grouped by the number of times treated for BRD (BRDX) and randomly allocated to finishing pens. The BRDX experimental groups included never treated for BRD (0X; 8 pens) and treated 1 time (1X; 8 pens), 2 times (2X; 8 pens), or 3 or 4 times (3/4X; 8 pens). Arrival BW was not different among BRDX groups (P = 0.17); however, BRDX during the receiving period decreased performance, resulting in BW of 324, 316, 285, and 260 kg for 0X, 1X, 2X, and 3/4X, respectively, at the start of finishing (P < 0.001). Ultrasound estimates, BW, and visual appraisal were used to target a common body composition (average days on feed = 182). With increasing BRDX, days on feed increased linearly (P = 0.002), whereas HCW, DP, rib eye area, QG, and unconsolidated lungs decreased linearly (P ≤ 0.03). These results suggest that with additional days on feed, calves treated multiple times for BRD are able to reach similar compositional endpoints as their untreated cohorts; however, it may not be possible for these calves to reach the same QG and carcass yield.

Effect of health status on fattening performance in young crossbred polish Holstein-Friesian × Limousin Bulls and steers

The aim of this study was to determine the effect of disease incidence on selected parameters of cattle fattening performance and carcass quality, and the fatty acid profile of beef. The experimental materials comprised 16 bulls and 16 steers, Polish Holstein-Friesian × Limousin crossbreeds (including 10 healthy and six treated animals of each category). At 5 weeks of age, bloodless castration was carried out using a rubber elastrator. The calves were fed milk replacer provided in automatic feeding stations. Until 540 days of age, the animals were fattened in an Animal Research Laboratory equipped with the Roughage Intake Control (RIC) system (Insentec, the Netherlands). In comparison with healthy (untreated) bulls and steers, sick (treated) animals had lower average body weight at 180 days of age, by 37 kg (P ≤ 0.05) and lower average final body weight at 540 days of age, by 56 kg (P ≤ 0.05). Sick animals were characterized by lower feed intake and worse feed efficiency (not statistically significant differences). Hot carcass weight reached 318 kg in healthy animals and 258 kg in treated bulls (P ≤ 0.05). In treated steers, the percentage of lean meat and bones in the three-rib section was higher and the percentage of fat was lower, compared with their healthy counterparts (P ≤ 0.01). There was a category × health status interaction for carcass tissue composition. There were no significant influences of type of sickness on analyzed traits. In comparison with healthy steers, intramuscular fat of Musculus longissimus dorsi (MLD) from treated steers had significantly (P ≤ 0.05) higher concentrations of polyunsaturated fatty acids (n-6 and n-3) and a lower content of conjugated linoleic acid.

Genomic Tools and Animal Health

Animals have been selected to improve their productivity in order to increase the profitability to the producer. In this scenario, not much attention was given to health traits. As a consequence of that, selection was made for animals with higher production and a shortened productive life. In addition to that, the intense production system used in livestock has forced animals to be exposed to higher pathogen loads, therefore predisposing them to infections. Infectious diseases are known to be caused by micro-organisms that are able to infect and colonize the host, affecting their physiological functions and causing problems in their production and on animal welfare. Even with the best management practices, diseases are still the most important cause of economic losses in the animal industry. In this review article we have addressed the new tools that could be used to select animals to better cope with diseases and pathogens.

Expression of the Bovine NK-Lysin Gene Family and Activity against Respiratory Pathogens

Unlike the genomes of many mammals that have a single NK-lysin gene, the cattle genome contains a family of four genes, one of which is expressed preferentially in the lung. In this study, we compared the expression of the four bovine NK-lysin genes in healthy animals to animals challenged with pathogens known to be associated with bovine respiratory disease (BRD) using transcriptome sequencing (RNA-seq). The expression of several NK-lysins, especially NK2C, was elevated in challenged relative to control animals. The effects of synthetic peptides corresponding to functional region helices 2 and 3 of each gene product were tested on both model membranes and bio-membranes. Circular dichroism spectroscopy indicated that these peptides adopted a more helical secondary structure upon binding to an anionic model membrane and liposome leakage assays suggested that these peptides disrupt membranes. Bacterial killing assays further confirmed the antimicrobial effects of these peptides on BRD-associated bacteria, including both Pasteurella multocida and Mannhemia haemolytica and an ultrastructural examination of NK-lysin-treated P. multocida cells by transmission electron microscopy revealed the lysis of target membranes. These studies demonstrate that the expanded bovine NK-lysin gene family is potentially important in host defense against pathogens involved in bovine respiratory disease.

Use of Genomic Tools to Improve Cattle Health in the Context of Infectious Diseases

Although infectious diseases impose a heavy economic burden on the cattle industry, the etiology of many disorders that affect livestock is not fully elucidated, and effective countermeasures are often lacking. The main tools available until now have been vaccines, antibiotics and antiparasitic drugs. Although these have been very successful in some cases, the appearance of parasite and microbial resistance to these treatments is a cause of concern. Next-generation sequencing provides important opportunities to tackle problems associated with pathogenic illnesses. This review describes the rapid gains achieved to track disease progression, identify the pathogens involved, and map pathogen interactions with the host. Use of novel genomic tools subsequently aids in treatment development, as well as successful creation of breeding programs aimed toward less susceptible livestock. These may be important tools for mitigating the long term effects of combating infection and helping reduce the reliance on antibiotic treatment.

Prophylactic nitric oxide treatment reduces incidence of bovine respiratory disease complex in beef cattle arriving at a feedlot

Bovine respiratory disease complex (BRDc), is a challenging multi-factorial health issue caused by viral/bacterial pathogens and stressors linked with the transport and mixing of cattle, negatively impacting the cattle feedlot industry. Nitric oxide (NO) is a naturally occurring molecule with antimicrobial attributes. This study tests whether NO can prevent the symptoms associated with BRDc. Eighty-five, crossbred, multiple-sourced, commingled commercial weaned beef calves were monitored and scored for temperature, white blood count, clinical score, hematology, cortisol levels and neutrophil/lymphocyte ratio. NO treatment or placebo were given once on arrival to the stockyard. After one week 87.5% of sick animals were from the control while 12.5% from treatment groups and after two weeks 72% and 28% respectively. Treatment was shown to be safe, causing neither distress nor adverse effects on the animals. These data show that NO treatment on arrival to the feedlot significantly decreased the incidence of BRDc in this study.

Impact of health management, health treatments, and zilpaterol hydrochloride supplementation on carcass quality, color, and palatability traits in heifers

Two hundred sixty-eight strip loins were collected from heifers fed at Oklahoma State University in Stillwater, OK. In Exp. 1, heifers (n = 127) were assigned to 1 of 3 health management treatment groups: antimicrobial administrations were given based on standard feedlot protocol (SFP) or ruminal temperature (RT) or given a metaphylactic treatment of tulathromycin (MT) followed by visual assessment (VA). In Exp. 2, heifers (n = 155) were assigned to the same treatment groups as above and were supplemented zilpaterol hydrochloride (ZH) or control (CON). Three steaks were collected from each strip loin, 1 each for retail display, sensory evaluation, and Warner-Bratzler shear force (WBSF). Color was evaluated from the retail display steak using a trained color panel and objectively using a HunterLab Miniscan XE. An Instron Universal Testing Machine with a Warner-Bratzler head was used for evaluation of instrumental tenderness, and a trained sensory panel was used to assess palatability traits. Heifers treated by VA had the least number of antimicrobial administrations and lowest yield grade and also had the lightest HCW (P < 0.05) compared with the heifers treated by the other health management protocols. There were no subjective color attribute differences or sensory panel differences (P > 0.05) across all health management systems or antimicrobial administrations. There were no differences in carcass and performance traits for any antimicrobial administrations treatment groups (P > 0.05). Heifers who had 0 or 1 antimicrobial administrations had lower (P < 0.05) a* (redness/greenness: positive values = red and negative values = green), and b* (yellowness/blueness: positive values = yellow and negative values = blue) values compared with those who had 2 antimicrobial administrations. In Exp. 2, heifers treated by VA had the least number (P < 0.05) of antimicrobial administrations when compared with MT and RT. Health management group did not have any other effects on carcass, sensory, or color attributes. Zilpaterol hydrochloride supplementation caused a decrease (P < 0.05) in internal fat and yield grade, but no interactions were observed between the number of antimicrobial administrations and ZH supplementation. With the supplementation of ZH, WBSF significantly increased (P < 0.05). At the end of retail display, the control group had a greater (P < 0.05) surface discoloration when compared with the ZH group. Treatment and detection of bovine respiratory diseases (BRD) is critical to the industry economically and results from this study show that different methods can be used to detect BRD without dramatically impacting carcass, sensory, and retail case life characteristics.

Impact of respiratory disease, diarrhea, otitis and arthritis on mortality and carcass traits in white veal calves

Background

Little is known on the effects of common calf diseases on mortality and carcass traits in the white veal industry (special-fed veal), a highly integrated production system, currently criticized for the intensive pro- and metaphylactic use of antimicrobials. The objective of the present study was to determine the impact of bovine respiratory disease (BRD), diarrhea, arthritis and otitis on the economically important parameters of mortality, hot carcass weight (HCW), carcass quality, fat cover and meat color. For this purpose, a prospective study on 3519 white veal calves, housed in 10 commercial herds, was conducted. Case definitions were based on clinical observation by the producers and written treatment records were used.

Results

Calves received oral antimicrobial group treatments in the milk during 25.2% of the production time on average. With an increasing percentage of the production cycle spent on oral antimicrobials, HCW reduced, whereas the odds for insufficient fat cover or an undesirable red meat color both decreased. Of the calves, 14.8%, 5.3%, 1.5% and 1.6% were individually diagnosed and treated for BRD, diarrhea, arthritis and otitis, respectively. Overall, 5.7% of the calves died and the mortality risk was higher in the first weeks after arrival. Calves that experienced one BRD episode showed a 8.2 kg reduction in HCW, a lower fat cover and an increased mortality risk (hazard ratio (HR) = 5.5), compared to calves which were not individually diagnosed and treated for BRD. With an increasing number of BRD episodes, these losses increased dramatically. Additionally, calves, which experienced multiple BRD episodes, were more likely to have poor carcass quality and an undesirable red meat color at slaughter. Arthritis increased the mortality risk (HR = 3.9), and reduced HCW only when associated with BRD. Otitis did only increase the mortality risk (HR = 7.0). Diarrhea severely increased the mortality risk (HR = 11.0), reduced HCW by 9.2 kg on average and decreased carcass quality.

Conclusions

Despite the massive use of group and individual treatments to alleviate the most prevalent health issues at the fattening period, the effects of BRD, diarrhea, otitis and arthritis on survival and performance are still considerable, especially in cases of chronic pneumonia with or without arthritis. Controlling calf health by effective preventive and therapeutic strategies and in particular the prevention of chronic BRD is key for the profitability of veal operations.

A ten-year (2000-2009) study of antimicrobial susceptibility of bacteria that cause bovine respiratory disease complex--Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni--in the United States and Canada

Bovine isolates of Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni, collected from 2000 to 2009, were tested for in vitro susceptibility to ceftiofur, penicillin, danofloxacin, enrofloxacin, florfenicol, tetracycline, tilmicosin, and tulathromycin. Ceftiofur remained very active against all isolates. Penicillin retained good activity against P. multocida and H. somni isolates with no appreciable changes in susceptibility or minimal inhibitory concentration (MIC) distributions with time. While there was no obvious trend, the percent of M. haemolytica that were susceptible to penicillin ranged from 40.9% to 66.7%. Danofloxacin MIC(50) and MIC(90) values for M. haemolytica and P. multocida did not change beyond a single dilution over the 6 years it was included in the testing panel. The MIC(90) for H. somni increased beyond 1 dilution. Enrofloxacin MIC(50) values for the 3 pathogens also did not change over time, unlike the MIC(90) values, which increased by at least 4-doubling dilutions. Ninety percent or more of M. haemolytica and H. somni isolates were susceptible to florfenicol, while susceptibility among P. multocida was 79% or greater. Less than 50% of the isolates tested as susceptible to tetracycline in many of the years. All 3 organisms showed declines in tilmicosin and tulathromycin MIC(50) and MIC(90) values over the years in which they were tested.

Growth and Development Symposium: Impacts of inflammation on cattle growth and carcass merit

Inflammation caused by bovine respiratory disease (BRD) continues to be one of the greatest challenges facing beef cattle producers and feedlot managers. Inflammation decreases DMI, ADG, and G:F in feedlot calves, decreasing growth rate and increasing days on feed, which results in economic losses during the feeding period. During the past decade, marketing of feedlot animals has changed from selling cattle on a live basis to a grid-based marketing system. When cattle are marketed on a live basis, the economic effects of BRD stop at increased health cost and decreased feedlot performance, carcass weight, and death loss. However, when cattle are marketed in a grid-based system, inflammation has the potential to also affect carcass cutability and quality. The effects of inflammation on feedlot cattle in regards to performance are well understood; however, specific effects on cattle growth and ultimately carcass merit are not as well described. Recent studies in feedlot cattle have indicated that the incidence of BRD decreases both HCW and marbling; however, mechanisms are not understood. Research in other species has demonstrated that during the acute phase response, pro-inflammatory cytokines promote skeletal muscle catabolism to supply AA and energy substrates for immune tissues. Further, during this early immune response, the liver changes its metabolic priorities to the production of acute phase proteins for use in host defense. Together these dramatic shifts in systemic metabolism may explain the detrimental effects on performance and carcass traits commonly associated with BRD in feedlot calves. Moreover, recent studies relative to human health have revealed complex multilevel interactions between the metabolic and immune systems, and highlighted inflammation as being a significant contributor to major metabolic diseases. The objective of this paper is to review data to help explain the economical and physiological effects of inflammation on cattle growth and carcass merit.

Evolutionary process of Bos taurus cattle in favourable versus unfavourable environments and its implications for genetic selection

The evolutionary processes that have enabled Bos taurus cattle to establish around the globe are at the core to the future success of livestock production. Our study focuses on the history of cattle domestication including the last 60 years of B. taurus breeding programmes in both favourable and unfavourable environments and its consequences on evolution and fitness of cattle. We discuss the emergence of 'production diseases' in temperate production systems and consider the evolutionary genetics of tropical adaptation in cattle and conclude that the Senepol, N'Dama, Adaptaur and Criollo breeds, among others with similar evolutionary trajectories, would possess genes capable of improving the productivity of cattle in challenging environments. Using our own experimental evidence from northern Australia, we review the evolution of the Adaptaur cattle breed which has become resistant to cattle tick. We emphasize that the knowledge of interactions between genotype, environment and management in the livestock systems will be required to generate genotypes for efficient livestock production that are both economically and environmentally sustainable. Livestock producers in the 21st century will have less reliance on infrastructure and veterinary products to alleviate environmental stress and more on the animal's ability to achieve fitness in a given production environment.