Genetic analysis of the course of individual growth and feed intake of group-penned performance tested boars

Objective of the study was to analyse the course of feed intake and growth of 661 boars of three lines (259, 208, and 194 animals of lines 3, 4, and 8 , respectively) during an age dependent performance test between the 100(th ) and 170(th) day of age. Individual feed intake of the group-penned animal s was recorded by electronic feeding stations during the first, third, fift h, seventh, and ninth week on test. Additionally. each animal was weighted in biweekly intervalls. A second order polynomial and a third order polynom ial were individually fitted on feed intake and live weight. From these cur ves, individual information about daily feed intake, daily gain, and food c onversion ratio were derived for five periods of 12 days and for the entire period. Genetic parameters were estimated simultaneously using a multiple trait animal model, Heritabilities of h(2) = .50, .55, .40, and .39 for tra its of entire test period were found for backfat thickness, daily gain, dai ly feed intake, and food conversion ratio, respectively. Estimated heritabi lities for each test period from one to five were h(2) = .50, .56, .54, .50 , and .37 for daily gain, h(2) = .18, .43, .46, .45, and .38 for daily feed intake, and h(2) = .34, .42, .46, .44, and .39 for food conversion. The ge netic correlation between daily gain and food conversion in period one (r(g ) = -.84) was significantly different from correlations between these trait s in the following periods (r(g) = -.32 to -.51). Genetic correlations betw een daily gain and daily feed intake in each period were r(g) = .56 to .42 from first to last period, Except of first period (r(g) = .11), the genetic associations between food conversion and daily feed intake for periods wer e similar (r(g) = .52 to .56). The genetic associations indicate. that a hi gh feed intake in the beginning of the fattening period is desirable, while afterwards a more reduced feed intake should be achieved to improve effici ency of fattening performance. In order to optimise fattening performance, the use of part test information from growth rate and feed intake is necess ary.