An investigation was undertaken to evaluate the crossbred boar per se, and also to assess the value of including the American Hampshire into a first-cross sire. Groups of three boars were placed on each of 20 farms. Each group contained a purebred white (Landrace or Large White), a crossbred white and a crossbred Hampshire boar. Co-operators were asked to obtain at least six litters by each boar, record their performance to weaning, and provide a sample of the progeny of each boar to be reared under standard conditions to slaughter at 90 kg live weight. Breeding of the boars did not affect either the level or variability of litter performance. Differences in performance and carcass traits between the progeny of purebred and whitecross boars were found only for 'eye-muscle' area and fat depth ' C . Pigs sired by Hampshirecross boars had carcasses which were 2 % shorter than those from white boars.

The performance of progeny sired by Piétrain × Hampshire, Hampshire × Large White and Large White boars was compared over the live-weight range 28 to 65 kg. Feeding was twice daily to ‘appetite’ up to a maximum of 2·27 kg meal/day. Breed of boar did not influence rate or efficiency of live-weight gain, mid-line or internal fat depths nor muscle quality. Progeny of Pietrain × Hampshire and Hampshire × Large White sires, compared with those of Large White boars, had higher killing-out percentages (1·4 and 1·2 units) and larger eye muscles in cross-section (19·3 and 11·6%). Significant but small breed differences were noted in joint proportions of the carcass.