Behavioural patterns and performance in heterozygous or halothane free suckling piglets and growing gilts

The aim of this study was to compare the behaviour of halothane free pigs (NN) and heterozygous pigs (Nn) when they are raised under standard commercial conditions. A total of 110 suckling piglets (50 Nn and 60 NN) and 80 growing gilts (40 Nn and 40 NN) were observed in their farrowing or fattening pens. The observations were carried out in two trials (51 piglets and 40 gilts in trial 1 and 59 piglets and 40 gilts in trial 2). Instantaneous scan sampling was used to record the frequencies of resting, non-sucking activity, sucking/eating or interactions between individuals. The piglets and gilts were weighed one day after birth, at 20 and 180 days of age and average daily gain was estimated. The halothane genotype had, in general terms, a small and inconsistent effect on the behavioural patterns recorded for the observations of the piglets and gilts observations (i.e. both genotypes were seen to have similar frequencies for the behavioural patterns considered). No differences in body weight or average daily gain were found either between NN and Nn piglets or gilts. These results suggest that when pigs are raised under conventional commercial groups, the behaviour of NN and Nn pigs would be more affected by environmental factors such as the time of day or age than the halothane genotype. © INRA, EDP Sciences, 2005.