As the pork industry continues to improve swine handling practices, the need for a greater understanding of swine temperament is apparent. Achieving this greater understanding may lead to improvements in pig handling, production efficiency and well being.

The objective of this research was to determine the differences within breeds for three temperament traits and the relationship of performance with each trait during a performance testing period.

Nucleus populations of Chester White, Duroc, Landrace and Yorkshire boars and gilts were used to estimate breed differences.  Backfat, loin muscle depth, estimated percent lean, days to 250 lb. and three temperament scores were measured on 4,774 pigs.

Temperament measures included a loading score, scale score and a vocal score (Table 1). Scores ranged from 1 (calm) to 5 (highly excited). Loading score was recorded while loading into the scale. Scale score and vocal score were recorded while the pig was in the scale while ultrasound measurements were taken.

After phenotypic analysis, it was determined that vocal score consisted of two categories – pigs were either vocal or not – so they are classified simply as “vocal” or “non-vocal.” Growth rate and percent lean were adjusted to 250 lb., while backfat and loin muscle depth were adjusted to the mean weight of 247 ± 1 lb.

Breed differences for temperament scores were estimated as odds ratios of a one score increase.  In other words, what would be the odds of a scale score increasing from a 2 to a 3 when compared for different breeds (Table 2).

The odds of a higher loading score were greater for Landrace compared to Yorkshire (1.30) and Duroc (1.55), while Chester White compared to Yorkshire and Duroc were 1.31 and 1.56, respectively, more likely to have an increase in loading score.

Chester White pigs were more likely to have higher scale score than Yorkshire (1.40) and Duroc (1.83). Landrace also had a greater probability of a higher scale score than Chester White (1.77), Yorkshire (2.46) and Duroc (3.24), respectively.  Yorkshires were 1.32 times more likely to have an increase of one scale score than Duroc.

For vocal score, Chester Whites were 1.62 times more likely than Durocs, while Yorkshires were 1.61 times more likely than Durocs to be vocal than non vocal. Landrace vocal score had a higher probability of increasing compared to Chester White (2.40), Yorkshire (2.42) and Duroc pigs (3.89).

Phenotypic correlations for scale score with vocal score, backfat, loin muscle depth, days to 250 lb. and percent lean were 0.32, -0.15, -0.13, 0.11 and 0.17, respectively. An increase of one scale score resulted in 0.03 in. less backfat, 0.03 in. less loin depth, and 1.3 ± 0.2 days longer to reach 250 lb.

Landrace were more excited and vocal in the scale than Chester White, Yorkshire and Duroc. Landrace were also more difficult to load than Duroc and Yorkshire. Chester Whites were more excited in the scale than Durocs and Yorkshires, and more vocal than Durocs. Yorkshires were more likely to have an increase in scale and vocal scores than Durocs.

Pigs that are more active in the scale have a greater tendency to be vocal. In general pigs with lower scale scores grew faster, were fatter and had greater loin muscle depth.