Using classification trees to detect induced sow lameness with a transient model.

Feet and legs issues are some of the main causes for sow removal in the US swine industry. More timely lameness detection among breeding herd females will allow better treatment decisions and outcomes. Producers will be able to treat lame females before the problem becomes too severe and cull females while they still have salvage value. The objective of this study was to compare the predictive abilities and accuracies of weight distribution and gait measures relative to each other and to a visual lameness detection method when detecting induced lameness among multiparous sows. Developing an objective lameness diagnosis algorithm will benefit animals, producers and scientists in timely and effective identification of lame individuals as well as aid producers in their efforts to decrease herd lameness by selecting animals that are less prone to become lame. In the early stages of lameness, weight distribution and gait are impacted. Lameness was chemically induced for a short time period in 24 multiparous sows and their weight distribution and walking gait were measured in the days following lameness induction. A linear mixed model was used to determine differences between measurements collected from day to day. Using a classification tree analysis, it was determined that the mean weight being placed on each leg was the most predictive measurement when determining whether the leg was sound or lame. The classification tree's predictive ability decreased as the number of days post-lameness induction increased. The weight distribution measurements had a greater predictive ability compared with the gait measurements. The error rates associated with the weight distribution trees were 29.2% and 31.3% at 6 days post-lameness induction for front and rear injected feet, respectively. For the gait classification trees, the error rates were 60.9% and 29.8% at 6 days post-lameness induction for front and rear injected feet, respectively. More timely lameness detection can improve sow lifetime productivity as well as animal welfare.

Factors associated with fatigued, injured, and dead pig frequency during transport and lairage at a commercial abattoir.

The objective of this study was to identify environmental and management factors that are associated with the frequency of fatigued, injured, and dead pigs on arrival and in resting pens during lairage at a commercial Midwest abattoir. The terms transport losses or total losses refer to pigs that die or become nonambulatory at any stage of the marketing process. In this study, fatigued, injured, and dead pigs were summed into a variable termed total losses. Relative humidity (%), temperature ( degrees C), wind speed (m/s), and dew point ( degrees C) data were collected on 12,333 trailer loads of pigs. Week, sort from barn (first or third pig removal from barn), farm, normal vs. split load type (from 1 or multiple barns), load crew, driver, trailer, and wind direction were used as fixed effects in the model for the analysis of losses per load using generalized mixed models for Poisson distributions. Seven temperature-humidity indices (THI) were calculated and compared as model covariates. Load time per pig, trailer density (pigs per trailer x average BW/trailer space; kg/m(2)), wait time before unloading at the abattoir, and wind speed were used as model covariates. The log of the number of hogs per trailer was used to standardize the response variable. The linear covariate density accounted for the greatest portion of variance (based on F-value) followed by the fixed effect sort from barn, the fixed effect load type (pigs from 1 or multiple barns within a farm), load time per pig linear covariate, and THI. Pigs transported to the abattoir from June through July experienced fewer losses (P < 0.001) when compared with pigs that were transported from November through December. Keeping other factors constant, the log of total losses (%) per load increased by 0.0102x + 0.000541x(2) per unit of THI and 0.0191 kg/m(2) of density. Similarly, of 9 farms, the poorest-performing farm in regards to total loss percentage experienced 0.93% more losses per load when compared with the farm with the least loss percentage. This study demonstrates that multiple environment and management factors influence the incidence of market hog transport losses.

Increased selectivity of Mitis-Salivarius agar containing polymyxin.

Incorporation of the antibiotic polymixin B sulfate in plates of Mitis-Salivarius medium at a level of 100 U per ml effectively suppressed the growth of gram-negative spreading organisms which occasionally overgrow Mitis-Salivarius plates of oral samples and make them unsuitable for enumeration and differentiation of streptococci. At the indicated level the antibiotic did not affect the growth or typical colonial characteristics of the oral streptococci.