A Meta-Analysis to Understand the Relationship between Pig Body Weight and Variation from Birth to Market

Simple Summary Understanding and managing variation in live weight within a pig population is key for swine producers to avoid economic penalties at processing plants. The objective of this meta-analysis was to determine the relationship between coefficient of variation (CV) and standard variation (SD) as a function of body weight for pigs and develop equations to predict CV and SD of a population of pigs from birth to market weight. Results reveal that there is a quadratic relationship between variation and body weight. Coefficient of variation decreases as live weight increases, but the slope is less pronounced as body weights became greater. Conversely, SD increases quadratically as body weight (BW) increases, with a less pronounced slope when BW is high within the population. Thus, the equations developed can be an effective tool for producers to predict normal BW variation within a group of pigs, which can then aid in the development of marketing strategies for finishing pigs. This meta-analysis aims to understand the changes in pig body weight (BW) variation from birth to market and develop prediction equations for coefficient of variation (CV) and standard deviation (SD) as a function of BW. Standard deviation is the measure of dispersion of a set of values from the mean and CV is the SD expressed as a percentage of the mean. Data collected from 16 papers and data sets yielded 117,268 individually weighed pigs with sample size ranging from 120 to 4108 pigs. Polynomial regression analysis was conducted separately for each variation measurement. The resulting prediction equations (CV (%) = 20.04 - 0.135 x (BW) + 0.00043 x (BW)(2), R-2 = 0.79; SD = 0.41 + 0.150 x (BW) - 0.00041 x (BW)(2), R-2 = 0.95) suggest that there is a quadratic decreasing relationship between the CV of a population and BW, the slope gets smaller as mean BW increases from birth to market. A quadratic increasing relationship is observed for SD, with slope being smaller as mean BW of pigs increases from birth to market. These prediction equations can be used by swine producers to estimate expected CV and SD of BW among a population of pigs.