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We evaluate the historically optimal producer-selected coverage options comprised of coverage length and level for each marketing month for various types of livestock insured with Livestock Risk Protection insurance. We begin with feeder cattle steers (600-900lbs) and then analyze the other types of feeder cattle, followed by fed cattle and swine. The optimal contracts are identified as those that have historically provided the highest probability of a positive net return and the highest average net return. We find that regardless of marketing month, the optimal contracts consist of relatively high coverage levels whereas the optimal length of the contracts varies across marketing months and by livestock type. The results are compared against actual policies purchased to evaluate whether producer decision patterns are in line with the current findings.

A hedonic model was employed to examine factors impacting feeder cattle prices at a monthly video auction in Tennessee. Home-raised cattle were estimated to have a $2 per cwt. premium and cattle that have been tested for PI-BVDV (persistent infections with bovine viral diarrhea virus) sold for a premium of $1.19 per cwt. We also show how price varies across sale months for steers and heifers, suggesting opportune times to market gender-specific lots. Corn price was interacted with an average weight per head of the lot to show that lighter cattle were negatively affected, while heavier cattle prices were positively affected by increasing corn prices.

The supply side of beef industry has not responded well to the rising demand for beef. This industry is still highly dependent on imported beef and feeder cattle for beef production to meet the local demand. The objective of this study is to analyse the impacts of different importation policy scenarios on beef industry in Peninsular Malaysia. A simulation model that based on estimated market model is used to analyse the policy. The findings imply that the number of import cattle for breeding (ICTB) should be maintained, while import of cattle for slaughter or feeder cattle should be increased by 20%. This will improve beef self-sufficiency level while stabilizing beef retail price.

Managing the presence of Salmonella in ground beef has been an ongoing challenge for the beef industry. Salmonella prevalence can vary regionally, seasonally, and within the animal, making the development of interventions difficult. The objective of this study was to assess the efficacy of an autogenous Salmonella vaccine in mitigating Salmonella in lymph nodes (LNs) of feedlot cattle. An autogenous vaccine was developed using the most common Salmonella enterica serovars (Salmonella Kentucky, Salmonella Anatum, Salmonella Muenchen, Salmonella Montevideo, and Salmonella Mbandaka) identified from cattle managed at a South Texas feedlot with historically high Salmonella prevalence. Fifty-five heifers were selected for even distribution across five groups: (i) BASE, which received no autogenous vaccinations and were harvested after the stocker stage, (ii) CNTRL, which received no autogenous vaccinations, (iii) FARM, which received autogenous vaccinations at the ranch only, (iv) SPLIT, which received autogenous vaccinations at both the ranch and feedlot, and (v) YARD, which received vaccinations at the feedlot only. One heifer each from the BASE and CNTRL groups did not complete the study. All treatment groups except BASE were harvested after reaching market weight. Left and right superficial cervical and subiliac LNs from each carcass were collected and analyzed for Salmonella presence, and positive samples were serotyped. No salmonellae were recovered from LNs derived from BASE, FARM, SPLIT, or YARD groups. Cattle in the BASE group were expected to have a low occurrence of Salmonella based on previous research. However, the percentage of Salmonella-positive animals in the CNTRL group was 20.0% (2 of 10), which is lower than expected based on historical data from the same feeding location. There could be several causes of decreased Salmonella presence in the LNs of control cattle, creating an opportunity for future investigation into the development of preharvest interventions to combat Salmonella in feedlots. HIGHLIGHTS

For voluntary traceability programs, a key interest for program designers and policymakers is how to encourage participation. We contend that participating in voluntary traceability can be viewed as a product characteristic, and thus serves as a source of product differentiation. We study the implicit market for traceability systems for the first known time. In our empirical example, we use stated choice experiments to link feeder cattle sellers and buyers through premiums and discounts for cattle traceability systems. Using results from discrete choice models, we simulate changes in traceability supply and demand in response to prices and policies. We find that cost-share policies might be an effective way of encouraging participation for feeder cattle sellers and could serve as an alternative to mandating traceability.

Objective This study determines bred heifer auction price response as the number of available bred heifers for purchase decreases while controlling for reproductive management characteristics and feeder cattle prices. Materials and Methods The data used in this study came from a bred heifer sale located on the Tennessee and Kentucky state line from 2008 through 2017, and a hedonic pricing model was estimated that considered months pregnant, breed, AI pregnancy, lot size, and timing of when the heifer was purchased in the sale. Results and Discussion We found that months pregnant, lot size, sale month, and heifer price affected the sale price of bred heifers. We also can concluded that bred heifer sale price increased until about 49% of all heifers available in the sale were purchased. Implications and Applications Beef cattle producers frequently buy and sell cattle through auction markets. However, more information on how timing of placement in the sale affects bred heifer values could be helpful in informing buyers on bid timing to purchase replacements at lower costs. Results suggest that bidding earlier, or waiting to bid later in the sale, could result in lower purchase prices of bred heifer when holding reproductive characteristics and feeder cattle prices constant. This is a unique study that provides insight into bidding timing for buyers to consider when purchasing bred heifers. These strategies could be helpful in selecting lots to bid on that have desired attributes but are being sold when prices are lowest.

PurposeThe purpose of this study is to examine empirically the conditional correlation between the major US indices (S&P500 index and Dow Jones Industrial index) and three selected meat commodities as: Feeder Cattle, Leen Hogs and Live Cattle during the period from July 22, 2010 to June 30, 2017.Design/methodology/approachIn this study, the authors use for the first time the GARCH-DECO (1,1) to examine empirically the conditional nexus between the major US indices (S&P500 index and Dow Jones Industrial index) and three selected meat commodities as; Feeder Cattle, Leen Hogs and Live Cattle during the period from July 22, 2010 to June 30, 2017.FindingsFrom the empirical findings, the authors conclude the existence of a highly significance of conditional heteroscedasticity parameters can demonstrate us to distinguish the nature of the volatility dependency between S&P500 index and Dow Jones Industrial index and three selected meat commodities indices.Originality/valueThis can find clear the significance of relationship in the process of financialization of the major US index and meat commodities indices in the case of this paper.

Effective early postnatal nutritional management is a crucial component of livestock production systems, and nutrient manipulation during this period has been shown to exert long-term consequences on beef cattle growth and physiology. Metabolic imprinting defines these biological responses to a nutritional intervention early in life that permanently alter physiological outcomes later in life. Early weaning has been used to study metabolic imprinting effects, given that it allows for nutritional manipulation of animals at a young age. This practice has been shown to enhance carcass characteristics in feedlot cattle and accelerate reproductive development of females. Another strategy to study the effects of metabolic imprinting without the need for early weaning is to provide supplements via creep feeding. Providing creep feed to nursing cattle has resulted in transient and long-term alterations in cattle metabolism, contributing to increased reproductive performance of developing heifers and enhanced carcass quality of feeder cattle. Collectively, results described herein demonstrate nutrient manipulation during early postnatal life exerts long-term consequences on beef cattle productivity and may be a strategy to optimize production efficiency in beef cattle systems.

Beside blood pathogens transmission, insects of the order Diptera affect livestock by visual and contact harassment; blood-feeders are responsible of painful bites and blood despoliation, generating behavioural modifications, anaemia and production losses. Knowledge of their economic impact is a basis for cost-effective control. Here, we measured the global impact of Diptera by comparing two batches of six feeder cattle, one in open air, the other protected by a mosquito net. Analytical data were: insect density in open air, and, for feeder cattle: tail-flick counts, hematocrit values (Ht), feed intake, feed conversion ratio (FCR) and live body weight gains (LBWG). Over a period of five months, results showed significant losses of LBWG of cattle exposed to insects, estimated at 8.0±1.5 Kg/month [2.7;13.3], with a total loss reaching 40.0±5.5 Kg/head. Main diurnal insects were Stomoxys spp. and M. crassirostris. There was a strong correlation between fly density and diurnal tail-flicks. Night trapping and tail-flicks showed a potentially important role of mosquitoes to be further explored. Ht of exposed animals was 3-4% lower than controls. FCRs indicated that exposed animals needed 33% more dry matter intake/Kg of LBWG. Economic assessment showed that dipterans were responsible of 10-11% loss of LBWG during the main growing period of feeder-cattle (10-15 months). A feedlot of 100 calves would register a total loss of 16,000$ within 5 months, which appears to be an unexpectedly huge loss caused by dipterans. Investing part of this money in fly control would probably be beneficial.

Despite its importance in many decisions throughout agriculture, limited empirical work has quantified how changes in primary demand impact producers operating at different levels of vertically‐connected industries. A structural system of equations was estimated to quantify the impacts of U.S. retail and export beef demand on fed and feeder cattle demand and supply. Increases in retail and export demand positively impact both feeder and fed cattle producers. The estimated transmission elasticities suggest that shifts in retail and export demand, whether positive or negative, accrue proportionally more to feeder cattle producers than fed cattle producers. Using estimates from previous literature of the effect of generic advertising on beef demand, simulation results suggest feeder and fed cattle producers would benefit from increasing beef checkoff assessments from $1 to $2. Furthermore, an increase in export demand of more than 3.5% from observed values would cover aggregate costs of implementing source and age verification. While primary suppliers are often not directly involved in primary demand activities in vertically‐connected industries, this study highlights the key economic value for primary suppliers to support demand enhancing activities.

This study evaluated the use of molecular breeding values (MBVs) for carcass traits to sort steers into quality grid and lean meat yield (LMY) groups. A discovery set of 2,609 animals with genotypes and carcass phenotypes was used to predict MBVs for LMY and marbling score (MBS) for 299 Angus, 181 Charolais, and 638 Kinsella Composite steers using genomic best linear unbiased prediction. Steers were sorted in silico into four MBV groups namely Quality (with MBVs greater than the mean for LMY and MBS), Lean (with MBVs greater than the mean for LMY but less than or equal to the mean for MBS), Marbling (with MBVs greater than the mean for MBS but less than or equal to the mean for LMY), and Other (with MBVs lower than the mean for LMY and MBS). Carcass phenotypes on the steers were then collected at slaughter and evaluated for consistency with the assigned MBV groups using descriptive statistics and least square analysis. Accuracy of MBV predictions was assessed by Pearson’s correlation between predicted MBV and adjusted phenotype divided by the square root of trait heritability. Genomic breed compositions were predicted for all steers to correct for possible population stratification and breed effects in the test model. The number of steers that met the expected carcass outcome was counted to produce actual percentages for each MBV group. Results showed that on average, Quality and Marbling groups had greater back-fat and more marbling across the three populations while Lean group had leaner carcasses. Carcass weights were similar across MBV groups. Within MBV groups, decreases in variability were observed for most traits suggesting improvement in carcass uniformity. Greater than 70% of the steers in Quality, Lean, and Marbling groups met the Quality Grid and Y1-LMY target for Angus and Charolais but not for Kinsella composite. The accuracy of MBV prediction ranged from 0.43 to 0.59 indicating that up to 35% of the observed carcass trait variability can be predicted, which suggests utility of MBV as a marker-assisted management tool to sort feeder cattle into uniform carcass endpoint groups under similar environmental and management conditions. Further investigation is warranted to evaluate the performance of feeder cattle sorted based on MBV and managed for different carcass endpoints as well as the cost–benefit implications for feedlot operations.

Made available in DSpace on 2022-04-28T19:40:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 One hundred and ninety nonlactating, pregnant beef cows (¾ Bos taurus and ¼ Bos indicus; 138 multiparous and 52 primiparous) were assigned to this experiment at 117 ± 2.2 d of gestation (day 0). Cows were ranked by parity, pregnancy type (artificial insemination = 102, natural service = 88), body weight (BW) and body condition score, and assigned to receive a supplement containing: (1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 95) or (2) an organic complexed source of Cu, Mn, Co, and Zn (AAC; Availa4; Zinpro Corporation, Eden Prairie, MN; n = 95). The INR and AAC provided the same daily amount of Cu, Co, Mn, and Zn, based on 7 g of the AAC source. From day 0 to calving, cows were maintained in a single pasture and segregated 3 times weekly into 1 of 24 individual feeding pens to receive treatments. Calves were weaned on day 367 (200 ± 2 d of age), managed as a single group for a 45-d preconditioning period (days 367 to 412), and transferred to a single oat (Avena sativa L.) pasture on day 412. Heifer calves were moved to an adjacent oat pasture on day 437, where they remained until day 620. Heifer puberty status was verified weekly (days 437 to 619) based on plasma progesterone concentrations. Steer calves were shipped to a commercial feedlot on day 493, where they were managed as a single group until slaughter (day 724). Plasma cortisol concentration was greater (P = 0.05) in AAC calves at weaning but tended to be less (P = 0.10) on day 370 compared with INR calves. Mean plasma haptoglobin concentration was greater (P = 0.03) in INR vs. AAC calves during preconditioning, and no treatment effects were noted (P = 0.76) for preconditioning average daily gain (ADG). Puberty attainment was hastened in AAC heifers during the experiment (treatment × day; P < 0.01), despite similar (P = 0.39) ADG between treatments from days 412 to 620. Expression of myogenin mRNA in the longissimus muscle was greater (P = 0.05) in INR vs. AAC heifers on day 584. No treatment effects were detected (P ≥ 0.24) for steer ADG from day 412 until slaughter, nor for carcass quality traits. Hepatic mRNA expression of metallothionein 1A was greater (P = 0.02) in INR vs. AAC steers on day 586. In summary, supplementing Co, Cu, Zn, and Mn as organic complexed instead of sulfate sources to beef cows during the last 5 mo of gestation did not improve performance and physiological responses of the steer progeny until slaughter, but hastened puberty attainment in the female progeny reared as replacement heifers. Department of Animal Science Texas A&M University, College Station Prairie Research Unit Mississippi State University Faculdade de Medicina Veterinária e Zootecnia Universidade Estadual Paulista Pontotoc Ridge-Flatwoods Branch Experiment Station Mississippi State University Zinpro Corporation Faculdade de Medicina Veterinária e Zootecnia Universidade Estadual Paulista

Beef cattle cultivation is a side job for farmers which is carried out by family labor and the incomes are used to finance various needs of the farmers’ family. This study aims to determine the use of family labor in beef cattle cultivation and the use of livestock sales. The research was carried out from October 2020 to April 2021 in two Women Farmers Groups (WFG) in Bengkulu City and Seluma Regency who received beef cattle assistance from the government. Data were analyzed descriptively. The results showed that in general, beef cattle cultivation was carried out jointly by man and women farmers with a labor allocation of 39.59%. In intensive farming, farmers are more dominant in cultivation activities amounting to 46.25%, while in semi-intensive farming women farmers are more dominant in cultivation activities (41.06%). The income from the sale of livestock are mainly used for children's education expenses and buying vehicles (91.67% each), building or renovating houses (87.50%), and buying feeder cattle (79.17%). For the development of beef cattle in farmer group, it is necessary to consider the cultivation system before determining the target of recipient of the program. The development by WFG is more suitable for semi-intensive cultivation systems.

Feeder cattle are a heterogeneous commodity whose prices differ in important ways relative to the cattle specified in the CME Group Feeder Cattle futures contract. This necessitates estimation of optimal feeder cattle hedge ratios to manage price risk. Corn price is an important and often overlooked consideration when estimating feeder cattle hedge ratios. Corn price impacts feeder cattle weight-price slides and associated hedge ratios, which can result in over- or under-hedging. Utilizing transaction data from four feeder cattle markets, we estimate hedge ratios conditioned on corn price and compare risk of using corn-conditioned hedge ratios to using hedge ratios not dependent on corn price. Feeder cattle hedge ratios vary substantially across time, sex, location, and weight, which necessitates more frequent and detailed hedge ratio estimation. However, hedging risk is not generally statistically or economically significantly reduced by using corn-conditioned hedge ratios.

Despite the regular use of macrolide-antibiotics in the diets of feedlot cattle, liver abscesses persist representing a financial burden to both pre- and post-mortem sectors of the beef industry. Alternative strategies, which simultaneously address liver infections and reduce the dissemination of antibiotic-resistant bacteria, are needed. An immunoglobulin-Y (IGY) product, developed to target Fusobacterium necrophorum and Trueperella pyogenes, was evaluated for the control of liver abscesses and its effect on macrolide-resistant Enterococcus growth from feces. Sixty-four Holstein steers (Initial BW= 384± 13.5kg) consuming a finishing diet (90% concentrate) for 188 days (Final BW= 660± 42 kg) were used in a completely randomized design where steer was experimental unit and treatments included: TYL (Tylosin phosphate fed at 90mg/hd/day; n = 32) or IGY (fed at 2.5g/hd/day; n= 32). Feed intake was recorded daily and BW was recorded every 28 days until slaughter. After 150 d on treatment fecal samples were randomly obtained from each treatment group four times (n = 40) and cultured on bile-esculine agar enriched with 8 μg/mL of erythromycin. Continuous variables of feedlot growth performance, carcass data and bacterial growth were analyzed using the MIXED procedure of SAS with the fixed effect of treatment and random effects of steer or sampling day, respectively. Ordinal carcass data were analyzed using the FREQ procedure of SAS observing the Cochran-Mantel-Haenszel value. Treatment did not affect DMI (P= 0.21), ADG (P = 0.50) or G:F (P = 0.36). Treatment neither affected hot carcass weight (P = 0.37) nor longissimus muscle area (P = 0.25). However, TYL resulted in greater back fat thickness than IGY (0.32 vs. 0.23 in.; P < 0.02) and consequently greater numerical yield grade (P < 0.02). Quality grade was not affected by treatment (P = 0.65). No treatment difference was observed for liver abscesses prevalence (TYL=63% vs. IGY=52%; P = 0.40) or severity (P = 0.23). There was a greater proportion of erythromycin-resistant Enterococcus growth for TYL than IGY (42.6 vs. 21.9%; P < 0.04). Specifically formulated IGY feed additives may be viable alternatives to antibiotics in feedlot cattle diets.

This study aims to evaluate the economic potential of Aceh cattle from the perspective of stock farmers, traders, and consumers as the three main players in the business. This study was conducted from June to August 2018 in Banda Aceh City and Aceh Besar District, Aceh Province, Indonesia. It used related literature and a survey method that involved interviews, observations, and questionnaires from 9 stock farmers, 23 traders, and 22 consumers to obtain data. The data presented descriptively and analyzed using SWOT (strengths, weaknesses, opportunities, and threats) analysis. The results show that the strength factors of the Aceh beef business are high selling prices, easy maintenance, the good taste of meat, and that do not shrink quickly when cooked. Meanwhile, the weakness factors are the limitation of the availability of seeds, traditional methods of assessing carcass weight during the buying and selling process, and the low productivity of the cattle compared with other breeds. The factors that become opportunities include the high demand for the beef, on both weekdays and religious holidays, the selling price tends to increase each year, and the government's commitment to increase local cattle productivity through various programs. However, there are certain threats to the development of these cattle, and they include the high price of calves, competition with other more productive breeds, the existence of other cheaper sources of animal protein, and a decrease in consumer purchasing power. The difference between the value of the strength and weakness factors was 0.12, which signified a positive result, while that between the opportunity and threat factors was −0.29, which signified a negative result. Furthermore, the coordinate value from the Cartesian field shows that the development of these cattle is in quadrant IV, which means that the prospect for development is still quite high, regardless of the threat. In conclusion, Aceh cattle have a high economic potential to be developed, which needs to be strengthened through the rebranding program while at the same time maintaining the sustainability of the Aceh cattle breed in Indonesia. Meanwhile, the government is expected to supervise and regulate the trade of these cattle to provide beef at an affordable price for consumers.

Concerns surrounding horizontal concentration, vertical coordination, regional procurement areas, and resultant thinly traded input markets have beset the U.S. beef industry for decades. In late 2016, Tyson Foods, Inc. announced to its suppliers that it would no longer purchase Holstein cattle at its Joslin, IL harvest facility. This alteration to Tyson's procurement policy provides a unique opportunity to estimate the degree and extent to which a firm‐level decision impacted the beef supply chain. Results indicate that Tyson's decision resulted in a 5.5% (3.5%) reduction in live (dressed) Holstein prices. This impact was immediate, and the updated equilibrium price relationship has persisted. Price impacts were more significant upstream; Holstein feeder cattle prices were reduced by 22% initially and struggled to find a new equilibrium level for more than two years, ultimately stabilizing 4.8% below pre‐announcement levels. We extend the price adjustment analysis to estimate impacts on U.S. Holstein feeder operations' revenues and gross margins, quantifying losses totaling $610 million annually.

The study objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on serum chemistry, complete blood count, and fecal Salmonella spp. count in high-risk beef cattle during a 56-d feedlot receiving period and the subsequent finishing period. Four truckload blocks of crossbred beef bulls (n = 300) and steers [n = 84; total n = 384; average initial body weight (BW) = 220 ± 16.2 kg] were sourced from regional auction markets and assigned randomly to treatments arranged in a 2 × 2 factorial. Blood samples were collected from two bulls nearest to the median BW on arrival in each pen (n = 96) and fecal samples were collected from cattle in block 3 (n = 96). The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) negative control (CON); 2) 13 g per animal daily of prepared B. subtilis PB6 product (CST); 3) 450 ppb dry matter (DM) chromium propionate (CHR); and 4) 13 g per animal daily of prepared B. subtilis PB6 product and 450 ppb DM chromium propionate (CST + CHR). Treatments were top dressed in feed bunks daily using 0.45 kg per animal ground corn carrier immediately following feed delivery. Data were analyzed using mixed models with repeated measures. Day affected all serum chemistry variables (P ≤ 0.03) except total CO2 (P = 0.34) and all complete blood count variables during receiving (P ≤ 0.02) except percentage basophils (P ≥ 0.12). During the overall receiving period, serum calcium was decreased (P = 0.02) by CHR. Cattle fed CHR had greater total leukocyte count (P = 0.04) and neutrophil count (P = 0.02) during the overall receiving period. Fecal Salmonella spp. count was markedly reduced in cattle fed CST on day 28 (P = 0.01) and overall (P = 0.07). Overall, these data provide metabolic and hematologic insight into the unique challenges presented by lightweight, high-risk feeder cattle. Notably, CST was found to be effective in mitigating fecal enumeration and presumably replication of Salmonella spp. in the gastrointestinal tract.

International audience; 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.

The mature size (MS) of cows in the United States is diverse, which leads to diversity in the MS of feeder cattle and hot carcass weights (HCW) of fed cattle. Cattle feeders must manage this inherent variation. Given that implants alter MS, they may be an effective tool to manage variation in HCW across groups of cattle. Two experiments were conducted to evaluate the interaction of MS and implant status in calf-fed steers. Steer calves from the same two sources were used in both experiments. Because breeding seasons were

This experiment evaluated the effects of supplementing a saponin-containing feed ingredient, manufactured from purified extract of Yucca schidigera [Micro-Aid (MA); DPI Global; Porterville, CA], on performance, health, and physiological responses of receiving cattle. A total of 105 recently weaned Angus x Hereford calves (75 steers and 30 heifers), originating from eight cow-calf operations, were obtained from an auction facility on day -2 and road transported (800 km; 12 h) to the experimental facility. Immediately after arrival on day -1, shrunk BW was recorded and calves were grouped with free-choice access to grass hay, mineral supplement, and water. On day 0, calves were ranked by sex, source, and shrunk BW, and allocated to one of 21 pens (5 calves/pen; being one or two heifers within each pen). Pens were assigned to receive a total mixed ration (TMR) and one of three treatments (as-fed basis): (1) 1 g/calf daily of MA (M1; n = 7), (2) 2 g/calf daily of MA (M2; n = 7), or (3) no MA supplementation (CON; n = 7). Calves received the TMR to yield 15% (as-fed basis) orts, and treatments were top-dressed from days 0 to 59. Calves were assessed for bovine respiratory disease (BRD) signs and TMR intake was recorded for each pen daily. Calves were vaccinated against BRD pathogens on days 0 and 21. Final shrunk BW was recorded on day 60, and blood samples were collected on days 0, 2, 6, 10, 14, 21, 28, 34, 45, and 59. ADG was greater (P = 0.03) in M2 vs. M1 and CON (1.53, 1.42, and 1.42 kg/day, respectively), and similar (P = 0.95) between M1 and CON calves. No treatment effects were detected for TMR intake (P = 0.52), whereas feed efficiency was greater (P ≤ 0.05) in M2 vs. M1 and CON calves (213, 200, and 204 g/kg, respectively) and similar (P = 0.40) between M1 and CON calves. No treatment effects were detected (P = 0.39) for diagnosis of BRD signs. The number of antimicrobial treatments required upon BRD diagnosis was greater (P ≤ 0.01) in CON vs. M1 and M2 (1.40, 1.05, and 1.10 treatments, respectively), and similar (P = 0.60) between M1 and M2 calves. No other treatment effects were detected (P ≥ 0.23), including circulating concentrations of hormones and metabolites, serum antibody titers to BRD pathogens, and mRNA expression of innate immunity genes in whole blood. Collectively, results from this experiment suggest that MA supplementation at 2 g/animal daily enhances performance and response to BRD treatment in high-risk cattle during feedlot receiving.

Mycoplasma bovis can be a bacterial inhabitant of the upper respiratory tract of healthy bovines. In body regions other that the upper respiratory tract however, M. bovis is associated with a number of clinical syndromes such as bovine respiratory disease (BRD). This study used two enzyme-linked immunosorbent assays to assess the sero-status of M. bovis-specific antibodies in Australian feeder cattle at the time of feedlot induction and at approximately 42 days on feed (follow-up). The apparent sero-prevalence of M. bovis-specific antibody at induction was estimated to be 3.5% (95% confidence interval [CI] 2.0-5.0%, 47/1354) and 25.3% (95% CI 21.9-28.8%, 343/1354) at follow-up. Exposure to M. bovis between induction and follow-up as demonstrated by an increase in serum antibodies was estimated to be 19.4% (95% CI 16.2-22.6%, 261/1349). Risk factors associated with sero-positivity at feedlot induction included the region where animals were 28 days prior to induction and saleyard exposure at least 27 days prior to induction. Risk factors associated with a sero-increase between induction and follow-up included breed, source region and access to water shared with an adjoining pen of animals. Of these, shared pen water was considered the most important (odds ratio [OR] 3.3, 95% CI 1.5-7.4, p = 0.003). Animals exposed to M. bovis between induction and follow-up were at a substantially increased risk of BRD (OR 2.2, 95% CI 1.4-3.4, p = 0.001). This is the first Australian study that has identified risk factors for M. bovis sero-positivity and sero-increase and shown an association between sero-increase and the risk of BRD in the feeder cattle population. These findings suggest that M. bovis is a significant pathogen in the Australian feeder cattle population. In addition, identification of defined risk factors associated with an increased risk of exposure to M. bovis can assist in the development of targeted control measures to reduce the economic impact of M. bovis associated disease and BRD in feeder cattle.