Daily gain, food intake and food efficiency in pigs during the growing period

Abstract

ABSTRACTThe non-linear modely = ae(−hW−c/W)was fitted to weekly calculated daily gain (DG), daily food intake (FI) and food efficiency (FE) of 653 barrows and gilts fedad libitumor restrictedly during a growing period from 27 to 108 kg live weight. Whereywas DG, FI or FE, W was live weight anda, bandcwere parameters. The model fitted well to the expected course of the traits, with an accuracy similar to that of quadratic polynomials. Parameters for one trait could simply be derived from the parameters for the other two traits. For each trait, four basic patterns were distinguished, depending on the signs ofbandc. Curves with a maximum (b> 0 andc> 0) occurred most frequently. In cases of curves with a maximum, the model could be reparameterized to a model with parameters having a simple biological meaning.Coefficients of determination in barrows averaged 0·29 for DG, 0·88 for FI and 0·45 for FE, whereas these values were somewhat lower in gilts. Withad libitumfeeding, a DG curve with a maximum was fitted in proportionately 0·83 of the barrows and 0·61 of the gilts. The maximum DG was on average at live weights of 64 kg for barrows and 77 kg for gilts. A maximum in the FI curve was predicted in proportionately 0·60 of the barrows and 0·39 of the gilts. Curves for DG and FI in gilts were less curvilinear than in barrows. FE curves, withad libitumfeeding, had a maximum in proportionately 0·59 of the barrows and 0·52 of the gilts. This predicted maximum FE was, on average, before the start of the growing period. Gilts had a higher FE than barrows from 35 kg body weight onwards, and the difference increased with increasing live weight. Differences in FE betweenad libitumand restricted feeding were small, with a tendency for animals fed at a restricted feeding level to be more efficient at the end of the growing period.Average FE curves and individual FI or DG curves were used for indirect prediction of individual DG or FI curves, respectively. The correlation between directly and indirectly predicted values of DG and FI at live weights of 30, 65 or 100 kg was about 0·7 inad libitumfed barrows and gilts, and greater than 0·8 in pigs fed at a restricted level. This indicates that the model is suitable to predict and control the course of individual daily gain by influencing the course of food intake.