Incidence Of Bovine Respiratory Disease Research Articles

Administering the maternal bovine appeasing substance improves overall productivity and health in high-risk cattle during a 60-d feedlot receiving period.

This experiment evaluated health, physiological, and performance responses of high-risk cattle administered the maternal bovine appeasing substance (mBAS) during feedlot receiving. Angus-influenced, newly weaned male calves (n = 120) were purchased from an auction facility. Calves arrived at the research feedyard on d -1 and body weight (BW) was recorded upon arrival (199 ± 1kg). Calves were ranked by arrival BW and received 1 of 2 treatments prior to initial processing (d 0): 1) 10mL of a mBAS (Ferappease®; FERA Diagnostics and Biologicals; College Station, TX) or 2) 10ml of mineral oil (CON; placebo). Treatments were applied topically to the nuchal skin area (5mL) and above the muzzle (5mL). Calves were vaccinated against Clostridium and respiratory pathogens, dewormed, implanted, band-castrated, and received metaphylaxis at initial processing, and then distributed into 10 drylot pens according to arrival BW and treatment (n = 12 calves/pen, 5 pens/treatment). Calves were reapplied treatments (mBAS or CON) concurrently with booster vaccination on d 14. Feed intake and incidence of bovine respiratory disease (BRD) were recorded daily. Blood and hair samples from the tail-switch were collected on d 0, 14, 28, 42, and 60 for analysis of physiological variables. Calves were sampled for nasal microbiota analysis via swab on d 0, 14, and 28. Final shrunk BW was recorded on d 61 after 16h of feed and water restriction. Calf BW gain and final BW did not differ between treatments (P ≥ 0.40). Incidence of BRD was similar (P = 0.99) between mBAS and CON (56.7% for both treatments; SEM = 6.45). A greater (P = 0.04) proportion of mBAS calves diagnosed with BRD required a single antibiotic treatment to regain health (70.6 vs. 47.0%; SEM = 8.32), and mortality was greater (P = 0.03) in CON calves diagnosed with BRD (17.6 vs. 2.94%; SEM = 5.133). Relative abundance of Mycoplasma in nasal microbiota was reduced (P = 0.04) in mBAS calves compared with CON (34.7 vs. 27.4%; SEM = 2.35). Cortisol concentration in hair from the tail-switch was less (P = 0.01) on d 28 for mBAS calves compared with CON. Administering mBAS improved (P = 0.04) total pen-based liveweight change during the experiment (498 vs. 309kg/pen; SEM = 65.2) and final pen-based total liveweight (2,676 vs. 2,484kg/pen; SEM = 65.4). Administration of mBAS to high-risk cattle decreased physiological stress markers, reduced mortality, and increased pen-based productivity during a 60-d receiving period.

88 Impacts of trace mineral source and ancillary drench on steer performance during a 60-day backgrounding phase

Abstract This experiment evaluated the impacts of supplementing organic complexed Cu, Co, Mn, and Zn on productive and health responses of high-risk beef cattle during a 60-d backgrounding phase. Crossbred steers (n = 120) were purchased at auction and transported to the experimental facility. Steer BW was recorded at arrival (d -1; initial shrunk BW = 227.7 ± 1.3 kg). On d 0, steers were ranked by BW and allocated to 1 of 8 groups (8 steers/group) and housed in drylot pens (6 m x 12 m) equipped with GrowSafe automated feeding systems (Model 8000; 2 bunks/pen; d 0 to 60). Groups were randomly assigned to receive a total mixed ration (TMR; 47% corn) containing: 1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 40); 2) organic complexed sources of Cu, Mn, Co, and Zn (AAC; Zinpro Availa 4; Zinpro Corp., Eden Prairie, MN; n = 40); or 3) AAC and an organic complexed trace mineral drench (APF; 30 mL/hd; Zinpro ProFusion, Zinpro Corp.) on d 0 and ancillary to morbidity treatment (n = 40). Diets provided the same daily amount of energy, protein, macro minerals and trace minerals based on 7 g/steer daily of Zinpro Availa 4. Steers were assessed for bovine respiratory disease (BRD) signs daily. Liver biopsies were performed on day 0, 28 and 60. Final BW was recorded on d 60 and 61. Blood samples were collected on d 0, 2, 6, 10, 13, 21, 28 and 45. No treatment differences were detected (P ≥ 0.23) for TMR intake, final BW, ADG, feed efficiency, or BRD incidence. Mean liver Co concentrations were greater (P = 0.02) in AAC and APF compared with INR steers. Mean liver Cu was greater (P = 0.02) in APF compared with AAC steers. Liver Zn tended to be greater (P = 0.10) on d 28 but less (P = 0.05) on d 60 for INR compared with AAC and APF steers. Plasma cortisol was least (P = 0.05) for steers supplemented with AAC on d 6, whereas AAC steers tended to have greater (P = 0.09) plasma cortisol on d 13 compared with APF. Plasma haptoglobin tended to be greater (P ≤ 0.10) for INR steers on d 28 and 45 compared with AAC and APF. While supplementing cattle with AAC or INR results in similar animal performance and clinical disease, AAC and APF reduces stress and acute phase protein responses.

148 Supplementing Bovacillus to newly weaned beef steers during a 90-d grazing period

Abstract This experiment compared performance, health, and physiological responses of high-risk stocker cattle receiving a Bacillus subtilis derivative during a 90-d grazing period. Crossbred steers (n = 120) were obtained from an auction yard and transported to the experimental facility. Steer shrunk body weight (BW) was recorded at arrival (d -1). This value was averaged with BW recorded on d 0 to represent initial BW (236 ± 2 kg). On d 0, steers were ranked by BW and allocated to 1 of 12 pastures (4-ha pastures; 10 steers/pasture). Pastures were randomly assigned to receive daily supplementation with dried distillers’ grains at 1% of BW containing either: 1) Bacillus licheniformis and B. subtilis ingredient (BOV; 2 g/steer daily of Bovacillus, Chr Hansen A/S, Horsholm, Denmark) or 2) no additive (CON). Cattle received treatments from d 0 to 90 while housed in pastures containing stockpiled grass forage, as well as free-choice access to water and a commercial mineral + vitamin mix without ionophores. Steers were assessed for bovine respiratory disease (BRD) signs daily, and shrunk BW recorded on d 91. Blood samples were collected, and BW recorded on d 0, 14, 28, 56, and 90. No treatment differences were detected (P ≥ 0.19) for glucose, non-esterified fatty acids, β-hydroxybutyrate, haptoglobin, or insulin-like growth factor 1, whereas a treatment × day interaction indicated increased cortisol in BOV cattle on d 56 (P < 0.01). A treatment × day interaction was detected for serum concentrations of parainfluenza type 3 antibodies, which was greater in BOV steers on d 90 (P < 0.01). No treatment differences were detected (P ≥ 0.23) for serum concentrations of antibodies against other BRD pathogen. Average daily gain (ADG) tended to be increased (P = 0.09) in BOV compared with CON steers from d 56 to d 90 (0.858 and 0.760 kg/d, respectively, although did not impact overall ADG (P = 0.48). No treatment differences were detected for steer final BW (P = 0.43). Total BW change per pasture was greater in BOV compared with CON (790 vs. 550 kg BW change; P = 0.02). No treatment differences were detected (P = 1.00) for BRD incidence, although steers removed from the experiment for health reasons tended to be increased in CON compared with BOV (P = 0.08). Despite lacking differences in health or physiological responses, B. licheniformis and B. subtilis supplementation increased overall production of BW in high-risk stocker steers during a 90-d grazing period.

An Evaluation of the Field Efficacy of Tildipirosin for Control of Bovine Respiratory Disease in Feedlot Calves in Bulgaria

Bovine respiratory disease (BRD) is one of the most common and economically important disease affecting feedlot industry throughout the world. The economic significance of this condition are high morbidity and mortality, decreased weight gains, reduced food utilization, low meet quality and additional therapeutic and prophylactic measures. The hypothesis of this study was that the use of metaphylactic protocol based on the risk to develop BRD would reduce morbidity and mortality. For this purpose, the aims of this study were to evaluate the effect of tildipirosin on the incidence of BRD in feedlot cattle. A total of 106 male beef calves were enrolled in the study. Calves were allocated randomly in control group (54 animals) and treatment (52 animals) group. The first group received subcutaneous injection of placebo while the second was treated with SC injection of tildipirosin. The observed BRD incidence was 35.2, and 9.6% for the calves in the control and treatment group, respectively (P = 0.012). These results suggest that the tildipirosin metaphylaxis tend to decrease the incidence of BRD in the first four weeks of the fattening period in beef cattle. In conclusion, metaphylactic protocols, based on the administration of tildipirosin in the high risk period can be used for management of BRD.

Effects of simplified group housing on behavior, welfare, growth performance, and health of preweaned dairy calves on a California dairy

Most US dairy calves are raised in individual hutches (IH) for biocontainment purposes and to facilitate monitoring and handling of calves. However, individual hutches typically restrict calves' activity and social interactions. Previous studies showed that group housing (GH) is beneficial to calf welfare and is associated with social benefits. The adoption of group housing (GH) on dairies is hindered by several concerns, with the primary concern being the potential for increased transmission of diseases due to heightened calf-to-calf contact. In light of this, our study aimed to compare the behavior, health, and growth outcomes of calves housed in groups of 3 to individually housed (IH) calves during the preweaning period. A total of 42 Holstein heifer calves on a commercial dairy in Northern California were enrolled in groups of 3 to different housing treatments; IH (n = 21) or GH (n = 21) between July and October 2020. Each treatment was composed of 7 groups of 3 calves each. Calves in the GH treatment were housed in groups of 3 from 6 to 10 d until 70 d of age. Individual pens consisted of one polyethylene hutch with a 1.5 m x 1.2 m outside exercise area. Group pens were constructed by assembling 3 polyethylene hutches with a 1.5 m x 3.6 m outside exercise area of wire panel fencing. Calves were weighed and measured for height at birth and weaning. Diarrhea and bovine respiratory disease (BRD) scores were recorded daily throughout the preweaning period. Cumulative incidence and hazard ratios were estimated for BRD and diarrhea for GH and IH. A Mixed model with pen as a random effect was specified to evaluate the effect of treatment. Group-housed calves gained 0.64 ± 0.02 kg/d while IH calves gained 0.65 ± 0.02 kg/d (P = 0.40). Similarly, there was no evidence for treatment differences in withers height gain in GH calves (0.22 ± 0.01cm/d) compared with IH calves (0.21 ± 0.01 cm/d) (P = 0.14). The cumulative incidence of BRD based on California scoring system in GH calves was 75 ± 9.68 compared with 66.66 ± 10.28% in IH calves (P = 0.73). Group-housed calves had a BRD hazard of 1.14 times that of IH calves (95% CI: 1.21-2.40; P = 0.74). The cumulative incidence of diarrhea (fecal score 3) in GH calves was 100% in comparison to 95.20 ± 4.66% in IH calves (P = 0.99). The mean proportion of scan observations of calves feeding on concentrates was significantly higher in GH (0.145 ± 0.004 per h) compared with IH calves (0.076 ± 0.003 per h) during the preweaning period (P < 0.001). The study results provide evidence that this simplified group housing system provides benefits of GH without detrimental short-term impacts during the preweaning period on calf growth and health.

Impacts of trace mineral source and ancillary drench on steer performance during a 60-day backgrounding phase

Nutritional approaches to optimize cattle health and performance during the receiving period are warranted. This experiment evaluated the impacts of supplementing organic complexed Cu, Co, Mn, and Zn on productive and health responses of high-risk beef cattle during a 60-day backgrounding phase. Crossbred steers (120) were purchased at auction and transported to the experimental facility, where BW was recorded (day−1; initial shrunk BW = 227.7 ± 1.3 kg). On day 0, steers were ranked by BW and allocated to one of eight groups and housed in drylot pens equipped with GrowSafe automated feeding systems (Model 8000; two bunks/pen). Groups were randomly assigned to receive a total mixed ration containing: (1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 40); (2) organic complexed sources of the same minerals (AAC; Zinpro Availa 4 based on a metal:amino acid complex ratio of 1:1 for Zn, Cu, and Mn in addition to cobalt glucoheptonate; Zinpro Corp., Eden Prairie, MN; n = 40); or (3) AAC and an organic complexed trace mineral drench (APF; 30 mL/hd; Zinpro ProFusion, Zinpro Corp.) on day 0 and with morbidity treatment (n = 40). Diets provided the same daily amount of all nutrients and minerals based on 7 g/steer daily of Zinpro Availa 4. Steers were assessed for bovine respiratory disease (BRD) signs daily. Liver biopsies were performed on days 0, 28 and 60. Blood samples were collected on days 0, 2, 6, 10, 13, 21, 28 and 45. No treatment differences were detected (P ≥ 0.23) for feed intake, final BW, average daily gain, or BRD incidence. Mean liver Co concentrations were greater (P = 0.02) in AAC and APF compared to INR steers. Mean liver Cu was greater (P = 0.02) in APF compared to AAC steers. Liver Zn tended to be greater (P = 0.10) on day 28 but less (P = 0.05) on day 60 for INR compared to AAC and APF steers. Plasma cortisol was lowest (P = 0.05) for AAC steers on day 6, whereas AAC steers tended to have greater (P = 0.09) plasma cortisol on day 13 compared with APF. Plasma haptoglobin tended to be greater (P ≤ 0.10) for INR steers on days 28 and 45 compared to AAC and APF. While supplementing cattle with AAC or INR results in similar animal performance and clinical disease, AAC and APF reduce stress and acute phase protein responses.

Genomic estimated breeding values for bovine respiratory disease resistance in Angus feedlot cattle.

Bovine respiratory disease (BRD) causes major losses in feedlot cattle worldwide. A genetic component for BRD resistance in feedlot cattle and calves has been reported in a number of studies, with heritabilities ranging from 0.04 to 0.2. These results suggest selection could be used to reduce the incidence of BRD. Genomic selection could be an attractive approach for breeding for BRD resistance, given the phenotype is not likely to be recorded on breeding animals. In this study, we derived GEBVs for BRD resistance and assessed their accuracy in a reasonably large data set recorded for feedlot treatment of BRD (1213 Angus steers, in two feedlots). In fivefold cross validation, genomic predictions were moderately accurate (0.23 ± 0.01) when a BayesR approach was used. Expansion of this approach to include more animals and a diversity of breeds is recommended to successfully develop a GEBV for BRD resistance in feedlots for the beef industry.

Supplemental trace minerals as complexed or inorganic sources for beef cattle during the receiving period.

To investigate effects of inorganic or complexed trace mineral source (zinc, copper, manganese, and cobalt) on receiving period performance and morbidity, crossbred beef heifer calves (n = 287) arriving on three delivery dates were used in a 42-d receiving trial. Heifers were processed after arrival, stratified by day -1 body weights (BW) and allocated randomly to eight pens (11 to 13 heifers/pen, 24 pens total). Within truckload, pens were assigned randomly to dietary treatment (n = 12 pens/treatment). Heifers were housed on 0.42-ha grass paddocks, provided ad libitum bermudagrass hay and provided dietary treatments in grain supplements fed daily. Treatments consisted of supplemental zinc (360mg/d), copper (125mg/d), manganese (200mg/d), and cobalt (12mg/d) from complexed (Zinpro Availa 4, Zinpro Corp. Eden Prairie, MN) or inorganic sources (sulfates). Heifers were observed daily for clinical bovine respiratory disease (BRD). If presenting BRD symptoms and rectal temperature ≥ 40 °C, heifers were deemed morbid and treated with antibiotics. Six heifers/pen were bled to determine serum haptoglobin concentrations on days 0, 14, and 28. Liver biopsies were taken on day 5 ± 2 and 43 ± 1 from three calves selected randomly from each pen for mineral status comparisons. Statistical analyses were performed using the MIXED, GLIMMIX, and repeated measures procedures of SAS 9.4 with truckload as a random effect and pen within truckload specified as subject. There tended to be a treatment by day interaction for BW (P = 0.07). Heifer BW did not differ on day 0 (P = 0.82) and day 14 (P = 0.36), but heifers fed complexed trace minerals had greater BW on day 28 (P = 0.04) and day 42 (P = 0.05). Overall average daily gains were greater for heifers fed complexed trace minerals (P = 0.05; 0.78 vs. 0.70kg, SE = 0.03). Heifers supplemented with inorganic trace minerals had greater BRD incidence (P = 0.03; 58 vs. 46%, SE = 3.6). Haptoglobin concentrations decreased throughout the trial (P < 0.001), and heifers fed complexed trace minerals tended to have a decrease in haptoglobin concentrations (P = 0.07). The source of trace mineral supplementation had no effect (P ≥ 0.20) on liver mineral concentrations and there were no treatment × day interactions (P ≥ 0.35). In conclusion, supplementing diets for the first 42 d after arrival with complexed trace mineral sources improved heifer performance as compared to heifers supplemented with inorganic trace minerals.

Associations of serostatus upon arrival with clinical respiratory disease, lung consolidation, and growth in veal calves

Respiratory tract infections remain a major problem during calf rearing, especially among milk (formula)-fed veal. Preconditioning of calves through appropriate colostrum management and vaccination could be helpful to address this issue. The objective of this study was to investigate whether the presence of serum antibodies against major respiratory tract pathogens (bovine respiratory syncytial virus, parainfluenza 3 virus, bovine coronavirus, Mycoplasmopsis bovis, Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica) and total serum IgG concentration in calves upon arrival at the veal facility were associated with the occurrence of clinical bovine respiratory disease (BRD) or lung consolidation in the first 3 wk, as assessed by both the Wisconsin BRD scorecard (based on 5 clinical signs: cough, rectal temperature, ear position, and nasal and ocular discharge) and by quick thoracic ultrasound scanning. Additionally, the association between calves' serostatus production parameters were explored. A prospective cohort study was conducted among 442 male dairy calves on a large veal calf facility in Belgium. Both clinical scoring and quick thoracic ultrasound scanning were performed on all calves at 4 key moments in the production cycle: arrival at the facility, initiation of first metaphylactic antimicrobial treatment at peak incidence of BRD (wk 1), end of the first metaphylactic treatment (short-term evaluation) and at wk 10 (long-term evaluation). Mixed effects logit regression models were fitted to quantify relationships. The outcomes of interest were clinical respiratory disease (Wisconsin BRD scorecard positive), lung consolidation (≥1 cm or ≥ 3 cm), average daily weight gain, and cold carcass weight. In the first week of production, incidence of lung consolidation (≥1 cm) quickly increased from 14.9% upon arrival to 43.0% at the peak of the BRD incidence, while clinical BRD increased from 3.6% to 16.1%. The main finding of this study was that calves who were seropositive for bovine respiratory syncytial virus and bovine coronavirus at arrival had reduced odds of developing lung consolidation at the peak of the outbreak, 0.58 odds ratio (95% CI: 0.38-0.89) and 0.37 odds ratio (95% CI: 0.20-0.69), respectively. No relationships between serum IgG concentration at arrival and the development of lung consolidations or clinical respiratory disease were found. Nevertheless, on average, throughout the first 10 wk of the fattening cycle, calves with failed transfer of passive immunity (serum IgG < 7.5 g/L) gained 40 g/d (95% CI: 10-70 g/d) less weight (average daily gain). Hence, ensuring that calves have a positive serostatus for these respiratory tract pathogens before entering the facility may help lower the incidence of lung consolidations, subsequently reducing treatment incidence and the adverse effects on primary economic outcomes.

Dynamics of the nasopharyngeal microbiome of apparently healthy calves and those with clinical symptoms of bovine respiratory disease from disease diagnosis to recovery.

Bovine respiratory disease (BRD) is a multifactorial disease complex in which bacteria in the upper respiratory tract play an important role in disease development. Previous studies have related the presence of four BRD-pathobionts (Mycoplasma bovis, Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica) in the upper respiratory tract to BRD incidence and mortalities in the dairy and beef cattle industry, but these studies typically only use one time point to compare the abundance of BRD-pathobionts between apparently healthy and BRD-affected cattle. The objective of this study was to characterize the longitudinal development of the nasopharyngeal (NP) microbiome from apparently healthy calves, and in calves with clinical signs of BRD, the microbiota dynamics from disease diagnosis to recovery. Deep nasopharyngeal swabs were taken from all calves immediately after transport (day 0). If a calf was diagnosed with BRD (n = 10), it was sampled, treated with florfenicol or tulathromycin, and sampled again 1, 5, and 10 days after antibiotic administration. Otherwise, healthy calves (n = 20) were sampled again on days 7 and 14. Bacterial community analysis was performed through 16S rRNA gene amplicon sequencing. The NP microbiome of the healthy animals remained consistent throughout the study, regardless of time. The NP microbiota beta diversity and community composition was affected by tulathromycin or florfenicol administration. Even though BRD-pathobionts were identified by 16S rRNA gene sequencing in BRD-affected animals, no difference was observed in their relative abundance between the BRD-affected and apparently healthy animals. The abundance of BRD-pathobionts was not predictive of disease development while the relative abundance of BRD pathobionts was unique to each BRD-affected calf. Interestingly, at the end of the study period, the genera Mycoplasma was the most abundant genus in the healthy group, while Lactobacillus was the most abundant genus in the animals that recovered from BRD. This study highlights that injected antibiotics seem to improve the NP microbiome composition (higher abundance of Lactobacillus and lower abundance of Mycoplasma), and that the relative abundance of BRD-pathobionts differs between individual calves but is not strongly predictive of BRD clinical signs, indicating that additional factors are likely important in the clinical progression of BRD.

PSXII-22 Analysis of the Upper Respiratory Tract Microbiome in Newly Received Feedlot Heifers According to Subsequent Incidence of Bovine Respiratory Disease

Abstract This study compared the relative abundance of bacteria in the upper respiratory tract (RT) of newly received feedlot heifers according to incidence of bovine respiratory disease (BRD). Angus-influenced heifers (n = 76) were transported for 1,100 km (11 h) to the feedlot (d -1). At feedlot arrival (d 0), heifers were weighed [initial shrunk body weight (BW) = 234 ± 15 kg] and a nasal swab collected for analysis of the upper RT microbiome. Heifers were ranked by arrival BW and allocated into 6 pens on d 1 where they remained until d 55. Heifers were evaluated daily for BRD signs (d 0 to 55), and a final shrunk BW was recorded on d 56 (16-h feed and water deprivation). Heifers were classified according to number of antimicrobial treatments for BRD received (0, 1, or ≥ 2), or according to time of first incidence of BRD signs [no incidence (NOBRD), early incidence (EARLY; 4.1 ± 0.1 d), or late incidence (LATE; 18.5 ± 9.6 d). All data were analyzed using heifer as the experimental unit, the PROC MIXED procedure of SAS and Satterthwaite approximation to determine the denominator degrees of freedom for tests of fixed effects. The first model statement included the number of BRD treatments received, the second model statement included the time of first incidence of BRD signs. Average daily gain decreased linearly (P = 0.04) according to number of BRD treatments and was less (P = 0.04) in LATE and tended (P = 0.08) to be less in EARLY compared with NOBRD heifers. The abundance of the phyla Tenericutes increased linearly (P &amp;lt; 0.01), while the abundance of Firmicutes, Bacteroidetes, Actinobacteria, Verrucomicrobia, Spirochaetes, Euryarchaeota, Chlorobi, and Chloroflexi decreased linearly (P ≤ 0.05) according to number of BRD treatments. Heifers classified as EARLY had greater (P = 0.01) abundance of Tenericutes and less (P = 0.03) abundance of Firmicutes compared with NOBRD, as well as less (P ≤ 0.03) abundance of Euryarchaeota and Chloroflexi compared with both NOBRD and LATE heifers. The abundance of the genera Mycoplasma increased linearly (P &amp;lt; 0.01) while the abundance of Corynebacterium, Blautia, Jeotgalicoccus, Clostridium, and Dietzia decreased linearly (P ≤ 0.03) according to number of BRD treatments. Heifers classified as NOBRD had less (P = 0.01) abundance of Mycoplasma compared with EARLY, and greater (P ≤ 0.05) abundance of Corynebacterium, Jeotgalicoccus, Dietzia, and Planomicrobium compared with EARLY and LATE heifers. Collectively, heifers that developed BRD had altered upper RT microbiome at the time of feedlot arrival compared with heifers that remained healthy, particularly increased prevalence of Tenericutes phylum and Mycoplasma genera. Such differences in upper RT microbiome were heightened in heifers that developed BRD shortly after arrival, or that required multiple antimicrobial treatments.

PSIII-23 Supplementing Bovacillus to Newly Weaned Cattle During a 90-Day Grazing Period

Abstract This experiment compared performance, health, and physiological responses of weaned cattle receiving Bacillus subtilis derivative in a 90-d grazing period. Recently weaned Angus-influenced steers (n = 120) were obtained from an auction yard on d -1 and transported 150 km to research facility. Immediately after arrival on d -1, shrunk body weight (BW) was recorded and steers were grouped with access to native forage and water. On d 0, an additional body weight was recorded and combined with d -1 values to represent initial body weight (BW; 236 ± 2 kg). Steers were ranked according to initial BW and allocated to 1 of 12 pastures (4-ha pastures; 10 steers/pasture). Pastures were randomly assigned to receive daily supplementation with dried distillers grains at 1% of BW with either: 1) Bacillus subtilis ingredient (BOV; 2 g/steer daily of Bovacillus; Chr Hansen A/S, Horsholm, Denmark), or 2) no additive (CON). Cattle received treatments for the duration of the experiment (d 0 to d 90) while housed in pastures containing stockpiled native forage, primarily Cynodon dactylon and Paspalum dilatatum, as well as free-choice access to water and a commercial mineral + vitamin mix not including ionophores. Bovine respiratory disease (BRD) signs were assessed daily throughout the experimental period. Steer unshrunk BW was recorded on d 14, 28, 56, and 90 and shrunk BW recorded on d 91 added 8% shrink as final BW. Blood samples and fecal swabs were collected from all steers on d 0, 14, 28, 56, and 90. Average daily gain (ADG) was increased in BOV groups compared with CON (0.858 and 0.760 kg/d, respectively) from d 56 to d 90 (P = 0.09) although this BW gain was not sufficient to impact final BW. Steer BW did not differ between treatments for all days (P ≥ 0.43). Incidence of BRD was within the expected range for high-risk stocker cattle, although the number of sick animals was not reduced due to BOV supplementation (P = 1.00). Steers not completing the trial due to health-related complications tended to be increased in CON vs. BOV (P = 0.08). Differences in percentage of steers not completing the experiment, in conjunction with treatment effects for ADG in the final third of the experiment, increased the production total BW per BOV pasture by 43% (790 vs. 550 kg BW change; P = 0.02). Bacillus subtilis supplementation was effective in increasing production BWt during a 90-d grazing period despite no observed difference in BRD incidence.

Current Knowledge on the Transportation by Road of Cattle, including Unweaned Calves.

Transport conditions have the potential to alter the physiological responses of animals to the psychological or physical stress of transport. Transportation may introduce multiple physical and psychological stressors to unweaned calves and adult cattle, including noise, overcrowding, food and water deprivation, extreme temperatures, commingling with unfamiliar animals, handling by unfamiliar humans, and being placed in a novel environment upon arrival. Apart from these factors, the type of road and even driving skill may affect the welfare of animals. One of the concerns regarding cattle transport is that the handling and marketing of animals prior to a journey may lengthen the period of feed withdrawal. Furthermore, feed withdrawal can impact animal welfare through hunger and metabolic stress. Transportation is also associated with a decrease in animal performance as well as an increase in the incidence of bovine respiratory disease. It is well established that the transportation of cattle is a stressor that causes a quantifiable response; however, excessive stress during transport resulting in physiological or pathological changes can be reduced with best management practices. The objective of this review was to analyse the available scientific literature pertaining to the transport by road of cattle, including unweaned calves.

Auction market placement and a rest stop during transportation affect the respiratory bacterial microbiota of beef cattle.

Bovine respiratory disease (BRD) is a significant health problem in beef cattle production, resulting in considerable economic losses due to mortalities, cost of treatment, and reduced feed efficiency. The onset of BRD is multifactorial, with numerous stressors being implicated, including transportation from farms to feedlots. In relation to animal welfare, regulations or practices may require mandatory rest times during transportation. Despite this, there is limited information on how transportation and rest stops affect the respiratory microbiota. This study evaluated the effect of cattle source (ranch-direct or auction market-derived) and rest stop duration (0 or 8 h of rest) on the upper respiratory tract microbiota and its relationship to stress response indicators (blood cortisol and haptoglobin) of recently weaned cattle transported for 36 h. The community structure of bacteria was altered by feedlot placement. When cattle were off-loaded for a rest, several key bacterial genera associated with BRD (Mannheimia, Histophilus, Pasteurella) were increased for most sampling times after feedlot placement for the ranch-direct cattle group, compared to animals given no rest stop. Similarly, more sampling time points had elevated levels of BRD-associated genera when auction market cattle were compared to ranch-direct. When evaluated across time and treatments several genera including Mannheimia, Moraxella, Streptococcus and Corynebacterium were positively correlated with blood cortisol concentrations. This is the first study to assess the effect of rest during transportation and cattle source on the respiratory microbiota in weaned beef calves. The results suggest that rest stops and auction market placement may be risk factors for BRD, based solely on increased abundance of BRD-associated genera in the upper respiratory tract. However, it was not possible to link these microbiota to disease outcome, due to low incidence of BRD in the study populations. Larger scale studies are needed to further define how transportation variables impact cattle health.

Impact of the host transcriptome on bovine respiratory disease treatment during backgrounding

Bovine respiratory disease (BRD) continues to be problematic across the beef cattle industry. Marketing strategies made prior to backgrounding may shift the initial treatment for BRD into a different phase of production, and the importance of host gene expression on BRD incidence is poorly understood. Whole blood transcriptomes measured on arrival could inform our ability to better manage these cattle and predict BRD risk. Our objective was to compare host transcriptomes as measured on arrival at a backgrounding facility on the probability of being treated for BRD during the following 45 days on feed.

The association between insemination eligibility and reproductive performance of nulliparous heifers on subsequent body weight and milk production of primiparous Holstein cows

The objective of this retrospective cohort study was to determine the association between insemination eligibility and reproductive performance of nulliparous heifers with subsequent body weight (BW) at 30 d in milk (DIM) and milk production at wk 4, 8, and 12 of lactation of primiparous cows. The final data set included 1,849 primiparous Holstein cows from a commercial dairy herd. Data extracted from a commercial dairy herd management software program included parent average predicted transmitting abilities (PTA), bovine respiratory disease (BRD) incidence, pregnancies per artificial insemination (P/AI) at first insemination as nulliparous heifers, BW at 30 DIM, percent mature body weight (%MBW), and mean weekly milk production at wk 4, 8, and 12 of lactation. Heifers were eligible for first insemination at 380 d of age and were detected in estrus and artificially inseminated with sexed semen. Quartiles based on BW at 30 DIM and %MBW were created in ascending order as follows: Q1 (lightest; n = 462), Q2 (light-moderate; n = 456), Q3 (moderate; n = 472), and Q4 (heaviest; n = 459). Only Q3 and Q4 cows achieved ≥85% MBW postcalving based on the herd MBW of 686.2 kg. The incidence of BRD during heifer development was greatest for Q1 cows, and Q1 cows had fewer days on feed as heifers than Q4 cows, resulting in a shorter growth period to achieve ≥85% MBW postcalving. Overall, Q1 cows had a greater PTA for daughter pregnancy rate and heifer conception rate than Q4 cows, which was associated with approximately 26 percentage points more P/AI at first insemination as heifers for Q1 than for Q4 cows. Finally, Q1 cows yielded approximately 5 kg per cow/d less milk than Q4 cows. Thus, insemination eligibility and reproductive performance of heifers, calfhood BRD incidence, and genetic potential for reproductive performance were associated with BW at 30 DIM and milk production at wk 4, 8, and 12 of lactation of primiparous cows.

Evaluation of practices used to reduce the incidence of bovine respiratory disease in Australian feedlots (to November 2021).

Bovine respiratory disease (BRD) has been identified as the most significant infectious disease of feedlot cattle in eastern Australia.1 Bovine respiratory disease causes economic loss due to medication costs, mortalities, excessive feed inputs associated with increased time on feed, reduced sale prices and associated labour costs. Bovine respiratory disease is a complex multifactorial condition with multiple animal, environmental and management risk factors predisposing cattle to illness. A range of microorganisms are implicated in BRD with at least four viral and five bacterial species commonly involved individually or in combination. The viruses most commonly associated with BRD in Australia are bovine herpesvirus 1 (BHV1), bovine viral diarrhoea virus (BVDV or bovine pestivirus), bovine parainfluenza 3 virus (PI3) and bovine respiratory syncytial virus (BRSV). More recently, bovine coronavirus has been identified as a potential viral contributor to BRD in Australia.2 A number of bacterial species have also been recognised as important to the BRD complex; these include Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Trueperella pyogenes and Mycoplasma bovis. Although one or more of the pathogens listed above can be isolated from clinical cases of BRD, there is no evidence that infection alone causes serious illness. This indicates that, in addition to specific infectious agents, other factors are crucial for the development of BRD under field conditions. These can be categorised as environmental, animal and management risk factors. These risk factors are likely to exert their effects through multiple pathways including reductions in systemic and possibly local immunity. For example, stressors such as weaning, handling at saleyards, transport, dehydration, weather conditions, dietary changes, comingling and pen competition might reduce the effectiveness of the immune system. Reduced immunocompetence can allow opportunistic infection of the lower airways with potential pathogens leading to the development of BRD. The objective of this paper is to critically review the evidence for management practices aimed at reducing the incidence of BRD in Australian feedlot cattle. Predisposing factors (Table 1) largely beyond the control of most feedlots, such as weather and exposure to respiratory viruses, are discussed separately, but these factors can generate indirect prevention responses that are discussed under the preventative practices categories. The current practices are classified as either animal preparation practices (Table 2) or feedlot management practices (Table 3).

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.

Influence of the At-Arrival Host Transcriptome on Bovine Respiratory Disease Incidence during Backgrounding

Bovine respiratory disease (BRD) remains the leading disease within the U.S. beef cattle industry. Marketing decisions made prior to backgrounding may shift BRD incidence into a different phase of production, and the importance of host gene expression on BRD incidence as it relates to marketing strategy is poorly understood. Our objective was to compare the influence of marketing on host transcriptomes measured on arrival at a backgrounding facility on the subsequent probability of being treated for BRD during a 45-day backgrounding phase. This study, through RNA-Seq analysis of blood samples collected on arrival, evaluated gene expression differences between cattle which experienced a commercial auction setting (AUCTION) versus cattle directly shipped to backgrounding from the cow-calf phase (DIRECT); further analyses were conducted to determine differentially expressed genes (DEGs) between cattle which remained clinically healthy during backgrounding (HEALTHY) versus those that required treatment for clinical BRD within 45 days of arrival (BRD). A profound difference in DEGs (n = 2961) was identified between AUCTION cattle compared to DIRECT cattle, regardless of BRD development; these DEGs encoded for proteins involved in antiviral defense (increased in AUCTION), cell growth regulation (decreased in AUCTION), and inflammatory mediation (decreased in AUCTION). Nine and four DEGs were identified between BRD and HEALTHY cohorts in the AUCTION and DIRECT groups, respectively; DEGs between disease cohorts in the AUCTION group encoded for proteins involved in collagen synthesis and platelet aggregation (increased in HEALTHY). Our work demonstrates the clear influence marketing has on host expression and identified genes and mechanisms which may predict BRD risk.

Short communication: Analysis of the nasal microbiota in newly received feedlot heifers according to subsequent incidence of bovine respiratory disease.

This study compared the relative abundance of bacteria in the nasal cavity of high-risk beef heifers at feedlot arrival according to subsequent incidence of bovine respiratory disease (BRD). Angus-influenced heifers (n = 76) were transported for 1,100 km (11h) to the feedlot (d -1). At feedlot arrival (d 0), heifers were weighed [shrunk body weight (BW) = 234 ± 15 kg] and a nasal cavity swab collected for microbiota analysis. Heifers were ranked by arrival BW and allocated into 6 pens on d 1 where they remained until d 55. Heifers were evaluated daily for BRD signs (d 0 to 55), and a final shrunk BW was recorded on d 56 (16-h feed and water deprivation). Heifers were classified according to number of antimicrobial treatments for BRD received (0, 1, or ≥2), or according to time of first incidence of BRD signs [no incidence (NOBRD), early incidence (EARLY; 4.1 ± 0.1 d, ranging from 3 to 6 d), or late incidence (LATE; 18.5 ± 9.6 d, ranging from 10 to 28 d). Average daily gain decreased linearly (P = 0.04) according to number of BRD treatments, and was less (P = 0.04) in LATE and tended (P = 0.08) to be less in EARLY compared with NOBRD. The abundance of the Tenericutes phylum increased linearly (P < 0.01), while the abundance of other phyla (e.g., Firmicutes and Bacteroidetes) decreased linearly (P ≤ 0.05) and phyla diversity tended to decrease linearly (P = 0.10) according to number of BRD treatments. Heifers classified as EARLY had greater (P = 0.01) abundance of Tenericutes compared with NOBRD, whereas Tenericutes abundance in LATE heifers was intermediate and did not differ (P = 0.22) compared with EARLY and NOBRD. The abundance of Mycoplasma genus increased linearly (P < 0.01) while the abundance of other genera (e.g., Corynebacterium and Blautia) and genera diversity decreased linearly (P ≤ 0.03) according to number of BRD treatments. Heifers classified as EARLY had greater (P = 0.01) abundance of Mycoplasma and reduced (P = 0.01) genera diversity compared with NOBRD, and values noted in LATE heifers for these variables were intermediate and not different (P ≥ 0.27) compared with EARLY and NOBRD. Hence, heifers that developed BRD during the experiment had altered nasal microbiota at arrival compared with heifers that remained healthy, particularly increased prevalence of Tenericutes and Mycoplasma. Such differences in nasal microbiota were heightened in heifers that developed BRD shortly after arrival, or that required multiple antimicrobial treatments.