Growth performance of pigs subjected to multiple concurrent environmental stressors.

Abstract

The effects of many single stressors have been reported, but how pigs perform when subjected to more than one or two stressors at a time, as is common in commercial swine production, has not. To study this, 256 Yorkshire x Hampshire or purebred Duroc pigs (34.7+/-.5 kg) were subjected to one of the eight treatment combinations (2 x 2 x 2 factorial) of ambient temperature (constant thermoneutral [24 degrees C] or high cycling temperature [28 to 34 degrees C]), stocking density (.56 or .25 m2/pig), and social group (static group or regrouped at the start of wk 1 and 3) during a 4-wk experiment. The temperature regimens were imposed in two adjacent mechanically ventilated rooms, and each temperature was imposed in each room across two trials. Four barrows and four gilts were assigned to each of the eight pens in the two rooms, and they always had free access to water and a corn-soybean meal-based diet. Treatments were imposed after a 7-d acclimation period at 24 degrees C and .56 m2/pig. Weight gain and feed intake were measured weekly. The main effects of each of the stressors for 4-wk ADG and ADFI were significant (P < .05). The stress of high temperature, high stocking density, and regrouping depressed 4-wk ADG by 12, 16 and 10% and ADFI by 7, 6, and 5%, respectively. Of the possible 60 stressor interactions for ADG, ADFI, and gain:feed (G:F), there were no significant three-way interactions and only six two-way interactions, suggesting that the effects of the individual stressors were additive. Accordingly, the growth rate of pigs subjected to the single stressor of high cycling temperature, restricted space allowance, or regrouping was depressed 10, 16, and 11%, respectively, and ADG of pigs subjected to all three stressors simultaneously was depressed by 31%. Stressor additivity was further corroborated by examining the effect of stressor order, or the number of stressors imposed simultaneously. As the number of stressors increased from 0 to 3, ADG, ADFI, and G:F decreased linearly. These data suggest that multiple concurrent stressors affect growth performance of pigs in a predictable fashion (i.e., additively) and indicate that avoidance or removal of a given stressor is advantageous even when other uncontrollable stressors persist.

Pig acute-phase protein levels after stress induced by changes in the pattern of food administration

“…Another study from our group showed similar elevations in the concentration of APP 1 day after the entering of the fattening barn, that were greater when pigs were mixed with animals that were previously unknown (Piñ eiro et al, 2004). Previous studies have shown that stressors have generally an additive effect (Hyun et al, 1998b); thus the presence of these initial stressors probably enhanced the effect caused by the disorderly feeding. Environmental conditions and handling prior to or during the trial apart from management of food, were identical for all the experimental groups; thus, as initial stressors would be acting for all the groups, including controls, differences observed between DIS and AL males, can be attributed to the management of feeding.…”

Heat stress upregulation of Toll-like receptors 2/4 and acute inflammatory cytokines in peripheral blood mononuclear cell (PBMC) of Bama miniature pigs: an in vivo and in vitro study

“…Many stressors that pigs are subjected to are associated with immunosuppressive effects that increase disease susceptibility (Hermann et al, 1993;Hyun et al, 1998). The total economic losses across animal classes because of heat stress are reported to average $2.4 billion annually in the United States (St-Pierre et al, 2003).…”

The impact of chronic environmental stressors on growing pigs, Sus scrofa (Part 1): stress physiology, production and play behaviour

“…Production parameters of weight gain, food conversion efficiency and back fat were recorded as a strong link between chronic stress and poor growth performance is frequently observed (e.g. Hyun et al, 1998;Sutherland et al, 2006;Foury et al, 2007). One of the key causal mechanisms of this relationship is thought to be the general catabolic influence of high circulating cortisol on certain muscle types and fat cells (Sapolsky et al, 2000;Yoshioka et al, 2005).…”