Population-level analysis of antibiotic use and death rates in beef feedlots over ten years in three cattle-feeding regions of the United States

OBJECTIVE To assess antibiotic use and other factors associated with death rates in beef feedlots in 3 regions of the US over a 10-year period. SAMPLE Data for 186,297 lots (groups) of finished cattle marketed between 2010 and 2019 were obtained from a database representing feedlots in the central, high, and north plains of the US. PROCEDURES Descriptive statistics were generated. Generalized linear mixed models were used to estimate lot death rates for each region, sex (steer or heifer), and cattle origin (Mexico or the US) combination. Death rate was calculated as the (number of deaths/number of cattle placed in the lot) × 100. Lot antibiotic use (TotalActiveMG/KGOut) was calculated as the total milligrams of active antibiotics assigned to the lot per live weight (in kilograms) of cattle marketed from the lot. Rate ratios were calculated to evaluate the respective associations between lot death rate and characteristics of cattle and antibiotic use. RESULTS Mean death rate increased during the 10-year period, peaking in 2018. Mean number of days on feed also increased over time. Mean TotalActiveMG/KGOut was greatest in 2014 and 2015, lowest in 2017, and moderated in 2018 and 2019. Death rate was positively associated with the number of days on feed and had a nonlinear association with TotalActiveMG/KGOut. Feeding medicated feed articles mitigated death rate. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested a balance between disease prevention and control in feedlots for cattle with various risk profiles. Additional data sources are needed to assess TotalActiveMG/KGOut across the cattle lifetime.

Valuing Cattle Manure as an Agricultural Resource for Efficiency and Environmental Sustainability

Within a context of beef feedlots and feed-crop production systems, we surveyed farmers to identify their perceived monetary value for the manure they used or could have used. Value is contextual with respect to a number of socio-economic, environmental, regulatory, and physical factors, which influence farmer’s inclinations about how they manage manure. The most desirable manure management strategies are likely practiced by those who perceive its value highest, and, conversely, the least desirable manure management strategies are likely practiced by those who assign the lowest value to it. This study considered factors that affect or relate to farmer perceptions of manure’s value. Using quantile regression, we observed variations in how farmers perceived the value of manure, considering farm and farmer characteristics, farming practices, select preferences, and whether or not they used manure on their own cropland. For example, we found that livestock producers who grow feed for their own cattle value manure differently compared to crop producers who do not manage cattle, most likely due to perceived need. Added years of experience in farming lowered the farmer’s perception of manure’s value. Additionally, extra tillage required when using manure was seen by farmers not as a burden but rather as a benefit.

Modeling Intervention Scenarios During Potential Foot-and-Mouth Disease Outbreaks Within U.S. Beef Feedlots

Foot-and-mouth disease (FMD) is a highly contagious disease of livestock and has severely affected livestock industries during the past two decades in previously FMD-free countries. The disease was eliminated in North America in 1953 but remains a threat for re-introduction. Approximately 44% of the on-feed beef cattle in the U.S. are concentrated in feedlots <32,000 heads, but little information is available on dynamics of FMD in large feedlots. Therefore, there is a need to explore possible management and intervention strategies that might be implemented during potential FMD outbreaks on feedlots. We used a within home-pen stochastic susceptible-latent-infectious-recovered (SLIR) FMD dynamics model nested in a meta-population model of home-pens in a feedlot. The combinatory model was previously developed to simulate foot-and-mouth disease virus (FMDv) transmission within U.S. beef feedlots. We evaluated three intervention strategies initiated on the day of FMD detection: stopping movements of cattle between home-pens and hospital-pen(s) (NH), barrier depopulation combined with NH (NH-BD), and targeted depopulation of at-risk home-pens combined with NH (NH-TD). Depopulation rates investigated ranged from 500 to 4,000 cattle per day. We evaluated the projected effectiveness of interventions by comparing them with the no-intervention FMD dynamics in the feedlot. We modeled a small-size (4,000 cattle), medium-size (12,000 cattle), and large-size (24,000 cattle) feedlots. Implementation of NH delayed the outbreak progression, but it did not prevent infection of the entire feedlot. Implementation of NH-BD resulted in depopulation of 50% of cattle in small- and medium-size feedlots, and 25% in large-size feedlots, but the intervention prevented infection of the entire feedlot in 40% of simulated outbreaks in medium-size feedlots, and in 8% in large-size feedlots. Implementation of NH-TD resulted in depopulation of up to 50% of cattle in small-size feedlots, 75% in medium-size feedlots, and 25% in large-size feedlots, but rarely prevented infection of the entire feedlot. Number of hospital-pens in the feedlot was shown to weakly impact the success of NH-TD. Overall, the results suggest that stopping cattle movements between the home-pens and hospital-pens, without or with barrier or targeted cattle depopulation, would not be highly effective to interrupt FMDv transmission within a feedlot.

Physically effective fiber changes nutrient levels of total mixed ration and fecal parameters in beef feedlots

ABSTRACT: This study evaluated the effects of the physically effective fiber (peNDF) content on nutrient composition of the total mixed ration (TMR), orts and fecal parameters in 15 commercial beef feedlots. The particle size distribution of TMR was measured adopting Penn State Particle Size Separator (PSPS). Samples were evaluated for dry matter (DM), ash, ether extract (EE), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and starch content. Fecal samples were also evaluated for pH and score. The feedlots were categorized into peNDF<20% and peNDF ≥ 20%. Data were analyzed by a model that included fixed effects of treatment and covariates (sex and genetic groups). Levels of DM, CP, EE and starch were lower in TMR with peNDF ≥ 20% (P<0.05). Fecal dry matter was higher and morning fecal pH was lower for TMR with peNDF<20% (P<0.05). Physically effective fiber changed nutrient levels in TMR, orts, fecal pH and DM. So, using PSPS and fecal parameters are practical and indirect tools for measuring fecal starch and assessing the effectiveness of the diet supplied to ruminants.

PSXII-12 Silages and roughage sources in the Brazilian beef feedlots

The aim of this survey was to identify silages and roughage sources adopted in the beef finishing diets. Eighty-two feedyards, located in 10 states, were surveyed from January to March 2019 for their feeding practices. Feedlot owners and nutritionists were interviewed by using a common survey form. The form consisted of 5 questions, including feedlot location, feedlot capacity and the number of animals serviced yearly, breed, silages and roughage sources, and roughage: concentrate ratio. Results were tabulated in an Excel spreadsheet for each feedlot. The number of responses per question, and the mean, minimum value, maximum value, and mode (most frequently occurring value) were calculated. Feedlot capacity ranged from 300 to 35,000 (mode = 3,000) and cattle serviced yearly per feedlot ranged from 400 to 90,000 (mode = 6,000). Nellore breed and crossbreed represented 74 and 26% % of finished animals, respectively. Roughage: concentrate ratio ranged from 40: 60 to 10: 90. Thirty-five percent of feedlots adopted 20: 80 ratio, followed by 15: 85 (16%) and 10: 90 (16%) ratios. Whole-plant corn silage was the most common roughage source (57%; Figure 1), followed by sugarcane bagasse (17%), tropical grass silages (16%), and whole-plant sorghum silage (11%). Nutritionists also cited hay (9%), sugarcane silage (5%), and fresh sugarcane (4%) as roughage sources. High-moisture corn, snaplage (grain, cob, husk, shank), and reconstituted grain corn were used by 20, 11, and 1% of feedlots, respectively. Reconstituted grain sorghum was included in 4% of the diets. Thus, 36% of feedlots adopted grain silages (corn and sorghum) in the diets. Overall, Brazilian feedlots have used high-energy finishing diets and corn is the most widely grown crop for silage. Feedlots have shown interest in using grain silages to maximize starch digestion, especially because Brazil grows flint corn and silage machinery industry has made available new equipment.