Defining “Approachability” of Nursery Pigs can Result in Differing Conclusions

Abstract

The objective of this experiment was to compare two approachability definitions of nursery pigs to a human observer in their home pen using a digital image. A total of 79 pens in two rooms (40 in room 1 and 39 in room 2) were used. A total of 1,817, ~6 wk old mixed sexed nursery pigs, weighing ~25.4 kg were used. Two definitions for pigs reacting to a human in their home pen were compared. Determining the approachability of pigs followed procedures used by Fangman et al., (2010). The experimental unit was the pen of pigs. Data used to evaluate nursery pig behaviors failed to meet the assumption of normally distributed data. These data were analyzed by using the PROC GLIMMIX procedure of SAS. A P-value of ≤ 0.05 was considered to be significant for all measures. There were differences in the number of pigs classified as Approaching, Look, or Not based on the definitions. There were more pigs classified as Approaching and fewer pigs classified as Look and Not when using the standard definition for WTA compared to the alternative definition. Therefore in conclusion, the definition for “approachability” becomes important, if it were to be used for on-farm welfare assessment or auditing. Additionally, using approachability without Look and Not would not provide the external observer complete information on the pigs comfort level. In particular, when pigs are recorded as “Not” it is vital that further classification of behaviors and postures are recorded. For example, are pigs feeding, drinking, socializing or resting. These entire main and sub behavioral classifications can then result in an accurate assessment of pig behavior when presented with a human in their home pen.