Relationships among serum characteristics and performance and carcass traits in growing pigs

Twelve blood serum components were determined on 78 barrows and 66 gilts, serially slaughtered at six age groups, starting at 69 d, at 2-wk intervals. One-half of the animals were fed ad libitum and one-half were fed "time restricted". Partial correlations between production and carcass traits and serum components were calculated from the residuals of the least-squares analysis. Calcium, serum protein and albumin were highly (P less than .01) correlated with several production and carcass traits. Creatinine was positively correlated (P less than .05) with backfat, loin fat, and percent dissected muscle and bone. Alkaline phosphatase showed a positive relationship with average daily gain (P less than .05) and percent dissected bone (P less than .01). A stepwise regression analysis was used to examine simultaneously the relative predictive value of the blood serum components. The nitrogenous compounds, which included albumin, total protein, urea and creatinine, were the most important predictors of performance (avg daily gain, feed conversion) and carcass composition. However, most of the serum components were not related to the performance and carcass composition traits.