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.

Birth weight threshold for identifying piglets at risk for preweaning mortality.

Several studies have suggested there is a critical relationship between piglet birth weight and preweaning mortality. Thus, the objective of the current work was to identify a birth weight threshold value for preweaning mortality. Birth weight and survival data from two studies involving a combined total of 4,068 piglets from 394 litters on four commercial farms (three European, one U.S.) were compiled for a pooled, multistudy analysis. Overall preweaning mortality across the two studies was 12.2%. Key variables used in the analysis were piglet birth weight (measured within 24 h of birth) and corresponding survival outcome (dead or live) by weaning at 3-4 wk of age. A mixed effects logistic regression model was fit to estimate the relationship between preweaning mortality and birth weight. A random effect of study was included to account for overall differences in mortality between the two studies. A piecewise linear predictor was selected to best represent the drastic decrease in preweaning mortality found as birth weight increased in the range of 0.5-1.0 kg and the less extreme change in weight above 1.0 kg. The change point of the birth weight and preweaning mortality model was determined by comparing model fit based on maximizing the likelihood over the interval ranging from 0.5 to 2.3 kg birth weight. Results from the analysis showed a curvilinear relationship between birth weight and preweaning mortality where the birth weight change point value or threshold value was 1.11 kg. In the combined data set, 15.2% of pigs had birth weights ≤1.11 kg. This subpopulation of pigs had a 34.4% preweaning mortality rate and represented 43% of total preweaning mortalities. These findings imply interventions targeted at reducing the incidence of piglets with birth weights ≤1.11 kg have potential to improve piglet survivability. Additional research is needed to validate 1.11 kg as the birth weight threshold for increased risk of preweaning mortality.

Assessing pitcher and catcher influences on base stealing in Major League Baseball.

A formal statistical analysis is performed to determine the extent to which pitchers and catchers can influence stolen-base attempts and successes. Two response proportions, attempt/opportunity and success/attempt, are modelled separately using mixed-effects logistic regression models applied to situations with a runner on first and other bases empty. Data include the first innings of all Major League Baseball games played between 1978 and 1990, which encompasses over 48,000 opportunities and 9000 attempts. Pitchers and catchers are entered as random effects and various other factors thought to influence stolen-base attempts and successes are entered as fixed effects. Variance components are estimated and hypotheses tests indicate that the population variance components for both pitchers and catchers are significant for both response proportions. The presence of variation among players at the respective positions is interpreted as evidence that stolen-base defence is a real skill exhibited to varying extents by different players. Furthermore, the variance component for pitchers is greater than that for catchers for both response proportions, indicating that pitchers have greater potential to affect stolen-base attempts and successes. Under usual conditions, it is estimated that 95% of pitchers have first-inning stolen-base success/attempt probabilities between 0.50 and 0.84, while 95% of catchers have probabilities between 0.59 and 0.79.