Effects of Positive Human Contact during Gestation on the Behaviour, Physiology and Reproductive Performance of Sows

Abstract

Previous positive interactions with humans may ameliorate the stress response of farm animals to aversive routine practices such as painful or stressful procedures, particularly those associated with stockpeople. We studied the effects of positive handling by providing younger (parity 1-2) and older (parity 3-8) sows housed in pens of fifteen (n = 24 pens in total) with either positive human contact (+HC) or routine human contact (control) during gestation. The +HC treatment involved a familiar stockperson patting and scratching sows and was imposed at a pen-level for 2 min daily. Measurements studied included behavioural, physiological and productivity variables. The +HC sows showed reduced avoidance of the stockperson conducting pregnancy testing and vaccination in the home pens, however the behavioural and cortisol responses of sows in a standard unfamiliar human approach test did not differ. There were no effects of +HC on aggression between sows, serum cortisol or serum brain-derived neurotrophic factor concentrations during gestation, or on the behavioural and cortisol response to being moved to farrowing crates. There were also no effects of +HC on the maternal responsiveness of sows, farrowing rate or the number of piglets born alive, stillborn or weaned. Sows in the +HC pens reduced their physical interaction with the stockpeople imposing the treatment after 2 weeks, which suggests the sows may have habituated to the novel or possible rewarding elements of the handling treatment. This experiment shows that regular positive interaction with stockpeople does reduce sows' fear of stockpeople, but does not always confer stress resilence.

Keywords: animal welfare; handling; positive human contact; reproduction; sows; stress.

Figure 1

Box and whisker plots of stockperson behaviour during positive human contact imposition on days 2, 5, 7, 9, 11, 15, 17, 28, 43, 58 and 73 of treatment. 1a shows the number of tactile interactions (patting, stroking, scratching) by stockpeople in each +HC treatment pen. 1b shows the proportion of sows in each +HC pen that stockpeople interacted with.

Figure 2

Sow behaviour during positive human contact imposition on days 2, 5, 7, 9, 11, 15, 17, 28, 43, 58 and 73 of treatment. 2a shows the mean number of tactile interactions (sniffing, nosing, chewing) with stockpeople initiated by older (solid line) and younger (dashed line) +HC sows. 2b shows the mean proportion of older (solid line) and younger (dashed line) +HC sows within 1 m of the stockperson during treatment imposition. Error bars represent standard error of the difference using single day analyses of variance, which did not require data transformation for number of sow interactions.