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-Daily feed intake data of 1 279 French Landrace (FL, 1 039 boars and 240 castrates) and 2 417 Large White (LW, 2 032 boars and 385 castrates) growing pigs were recorded with electronic feed dispensers in three French central testing stations from 1992-1994. Male (35 to 95 kg live body weight) or castrated (100 kg live body weight) group housed, ad libitum fed pigs were performance tested. A quadratic polynomial in days on test with fixed regressions for sex and batch, random regressions for additive genetic, pen, litter and individual permanent environmental effects was used, with two different models for the residual variance: constant in model 1 and modelled with a quadratic polynomial depending on the day on test d m as follows in model 2:Variance components were estimated from weekly means of daily feed intake by means of a Bayesian analysis using Gibbs sampling. Posterior means of (co)variances were calculated using 800 000 samples from four chains (200 000 each). Heritability estimates of regression coefficients were 0.30 (FL model 1), 0.21 (FL model 2), 0.14 (LW1) and 0.14 (LW2) for the intercept, 0.04 (FL1), 0.04 (FL2), 0.11 (LW1) and 0.06 (LW2) for the linear, 0.03 (FL1), 0.04 (FL2) 0.11 (LW1) and 0.06 (LW2) for the quadratic term. Heritability estimates for weekly means of daily feed intake were the lowest in week 4 (FL1: 0.11, FL2: 0.11) and week 1 (LW1: 0.09, LW2: 0.10), and the highest in week 11 (FL1: 0.25, FL2: 0.24) and week 8 (LW1: 0.19, LW2: 0.18), respectively. Genetic eigenfunctions revealed that altering the shape of the feed intake curve by selection is difficult. random regression / variance component / Gibbs sampling / feed intake / pig * Correspondence and reprints Present address: Swiss Brown Cattle Breeders' Federation,

Data on feeding behaviour of 3 710 group-housed and ad libitum fed growing pigs were recorded using 'Acema 48' electronic feed dispensers. Genetic parameters for six feeding behaviour criteria and the main production traits routinely recorded in French central test stations (three 'boar' traits and three 'sib' traits) were estimated in two breeds (Large White and French Landrace) using a multiple trait animal model DF-REML procedure. Heritability estimates for feeding behaviour criteria ranged from 0.36 to 0.54 and were markedly higher than that for the food conversion ratio (0.20). Heritability of daily feed intake was 0.42 in both breeds, whereas heritabilities of rate of feed intake, feed intake per meal and time per meal were slightly higher (0.45-0.54). Daily feed intake showed a very close genetic correlation (around 0.85) with average daily gain but also unfavourable genetic correlations with ultrasonic backfat thickness (around 0.5) and lean percentage (around-0.4). Daily feed intake was genetically independent of food conversion ratio, whereas average daily gain showed a favourable genetic correlation (around-0.35) with that trait. Among the feeding behaviour criteria, feed intake per meal and rate of feed intake showed the highest genetic correlations with daily feed intake (around 0.5) and average daily gain (around 0.4). They also showed moderately unfavourable genetic correlations with ultrasonic backfat thickness (around 0.25) and carcass lean percentage (around-0.25) and seemed to be genetically independent of food conversion ratio. The value of including a trait relating to feed intake pattern among traits selected for is discussed on the basis of this set of genetic parameters. pig / genetic parameter / feeding behaviour / electronic feed dispenser / production trait * Correspondence and reprints consommation. L'inclusion possible d'un critère de comportement alimentaire parmi les caractères sélectionnés est discutée sur la base de cet ensemble de paramètres génétiques. porc / paramètre génétique / comportement alimentaire / distributeur automatique d'aliment / caractère de production

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-Feed intake behaviour traits were recorded on 210 Large White and 114 Pietrain entire male pigs housed in single-breed groups (range of group size: 8-13) and having 24 h access to 'Acema 48' electronic feed dispensers. Three stages of growth were considered (average body weights of 39, 64 and 89 kg for both breeds), and feeding behaviour traits were calculated separately for two periods of the day (8-20 h and 20-8 (34.8 vs. 38.1 g ' min ' ', ', P < 0.01 Average time per meal (9.4 min), however, was not breed-dependent. Both breeds followed similar trends in feeding behaviour over the course of growth, even though the breed by stage of growth interaction was revealed to be significant for several traits. The nychthemeral distribution of feed intake was around 70 % and 30 % feed consumed in the 'daylight' and 'nightly' periods of day, respectively. The percentage of nightly feeding activity significantly decreased in the second part of the growth period. There were noticeable batch (season) and group size effects on most feed intake pattern traits but not on feed intake level. The latter trait showed a markedly lower repeatability across the three stages of growth (around 0.30)

Some misprints appeared on page 640, in Table II and in the last paragraph of Section 2.2 (line 9). One should read: "3.075 × 10 -2 ", "-4.900 × 10 -4 ", "1.440 × 10 -5 ", "2.500 × 10 -9 " and "1.0 × 10 -8 ", respectively (there are not exponential functions).

-A random regression model for daily feed intake and a conventional multiple trait animal model for the four traits average daily gain on test (ADG), feed conversion ratio (FCR), carcass lean content and meat quality index were combined to analyse data from 1 449 castrated male Large White pigs performance tested in two French central testing stations in 1997. Group housed pigs fed ad libitum with electronic feed dispensers were tested from 35 to 100 kg live body weight. A quadratic polynomial in days on test was used as a regression function for weekly means of daily feed intake and to describe its residual variance. The same fixed (batch) and random (additive genetic, pen and individual permanent environmental) effects were used for regression coefficients of feed intake and single measured traits. Variance components were estimated by means of a Bayesian analysis using Gibbs sampling. Four Gibbs chains were run for 550 000 rounds each, from which 50 000 rounds were discarded from the burn-in period. Estimates of posterior means of covariance matrices were calculated from the remaining two million samples. Low heritabilities of linear and quadratic regression coefficients and their unfavourable genetic correlations with other performance traits reveal that altering the shape of the feed intake curve by direct or indirect selection is difficult. random regression / variance component / Gibbs sampling / feed intake / pig

-A random regression model for daily feed intake and a conventional multiple trait animal model for the four traits average daily gain on test (ADG), feed conversion ratio (FCR), carcass lean content and meat quality index were combined to analyse data from 1 449 castrated male Large White pigs performance tested in two French central testing stations in 1997. Group housed pigs fed ad libitum with electronic feed dispensers were tested from 35 to 100 kg live body weight. A quadratic polynomial in days on test was used as a regression function for weekly means of daily feed intake and to describe its residual variance. The same fixed (batch) and random (additive genetic, pen and individual permanent environmental) effects were used for regression coefficients of feed intake and single measured traits. Variance components were estimated by means of a Bayesian analysis using Gibbs sampling. Four Gibbs chains were run for 550 000 rounds each, from which 50 000 rounds were discarded from the burn-in period. Estimates of posterior means of covariance matrices were calculated from the remaining two million samples. Low heritabilities of linear and quadratic regression coefficients and their unfavourable genetic correlations with other performance traits reveal that altering the shape of the feed intake curve by direct or indirect selection is difficult. random regression / variance component / Gibbs sampling / feed intake / pig