Summary and Implications
A selection experiment for reducing residual feed intake (RFI= feed consumed over and above expected requirements for production and maintenance) in Yorkshire pigs consists of a line selected for lower RFI (LRFI) and a random control line (CTRL). Using 64 LRFI and 87 CTRL boars from generation 5 of the selection experiment, cubic polynomial random regression with heterogeneous residual variance for daily feed intake (DFI) and with homogeneous residual variance for bi-weekly body weight (BW) were identified as the best linear mixed models to describe feed intake and body weight curves. Based on the Gompertz model, significant differences in the decay parameter for DFI and in mature body weight and the inflection point for BW were observed between the lines. In conclusion, selection for lower RFI has resulted in a lower feed intake curve toward maturity, lower mature body weight, and earlier inflection points for growth.
Iowa State University
Cai, Weiguo; Wu, Huaiqing; and Dekkers, Jack C.M.
"Analysis of Body Weight and Feed Intake Curves in Selection
Lines for Residual Feed Intake in Pigs ,"
Animal Industry Report:
AS 655, ASL R2455.
Available at: http://lib.dr.iastate.edu/ans_air/vol655/iss1/78