PSIV-17 - Weight variation of grow-finish pigs in commercial size pens

Abstract: Weight variation among hogs in grow-finish barns presents a significant management challenge and impacts both operational efficiency and profitability. Biological factors including genetics, sex, and health status disparities can lead to uneven growth rates. Environmental influences such as temperature, ventilation, and space allocation can exacerbate weight differences, particularly in commercial size pens. Therefore, the objective of this study was to measure the weight variation of grow-finish pigs housed in commercial size pens. A total of 1,144 weaned pigs had been previously allocated to 44 pens with 26 pig/pen (13 barrows and 13 gilts). At the start of this experiment, pigs were weighed individually and an electronic identification (EID) tag was applied to the left ear. On the subsequent weigh days, pigs were weighed individually and the EID was scanned to track the weight gain of each pig. Pigs were weighed three times after 9, 12, and 15 weeks on feed. The average body weights were 45±0.2, 66±0.3, and 87±0.3 kg, respectively. Five pens with the lowest standard error of body weights and five pens with the greatest standard error of body weights were identified for each weigh day. On the first weigh day, in four of the five lowest standard error pens, the median appeared equal to the mode, suggesting symmetrical data distribution and, in four of the five greatest standard error pens, the median appeared greater than the mode, suggesting that low weight pigs were contributing to the weight variation. On the second weigh day, there were five total pens where median appeared greater than mode (i.e. low weight pigs), three pens where median appeared equal to mode (i.e. symmetrical distribution), and only two pens where median appeared lower than mode (i.e. heavy weight pigs). On the third weigh day in a total of four pens, median appeared greater than the mode (i.e. low weight pigs), in a total of four pens, median appeared equal to mode (i.e. symmetrical distribution), and in two pens, median appeared less than mode (i.e. heavy weight pigs). Future research should explore advanced technologies including precision feeding to further minimize weight disparities and improve barn efficiency.