Factors affecting performance response of pigs exposed to different challenge models: a multivariate approach

Abstract

Factors associated with the severity with which different challenge models (CMs) compromise growth performance in pigs were investigated using hierarchical clustering on principal components (HCPC) analysis. One hundred seventy-eight studies reporting growth performance variables (average daily gain [ADG], average daily feed intake [ADFI], gain:feed [GF], and final body weight [FBW]) of a Control (Ct) vs. a Challenged (Ch) group of pigs using different CMs (enteric [ENT], environmental [ENV], lipopolysaccharide [LPS], respiratory [RES], or sanitary condition [SAN] challenges) were included. Studies were grouped by similarity in performance in three clusters (C1, C2, and C3) by HCPC. The effects of CM, cluster, and sex (males [M], females [F], mixed [Mi]) were investigated. Linear (LRP) and quadratic (QRP) response plateau models were fitted to assess the interrelationships between the change in ADG (∆ADG) and ADFI (∆ADFI) and the duration of challenge. All variables increased from C1 through C3, except for GF, which decreased (P < 0.05). LPS was more detrimental to ADG than ENV, RES, and SAN models (P < 0.05). Furthermore, LPS also lowered GF more than all the other CMs (P < 0.05). The ∆ADG independent of ∆ADFI was significant in LPS and SAN (P < 0.05), showed a trend toward the significance in ENT and RES (P < 0.10), and was not significant in ENV (P > 0.10), while the ∆ADG dependent on ∆ADFI was significant in ENT, ENV, and LPS only (P < 0.05). The critical value of ∆ADFI influencing the ∆ADG was significant in pigs belonging to C1 (P < 0.05) but not C2 or C3 (P > 0.10). The ∆ADG independent of duration post-Ch (irreparable portion of growth) was significant in C1 and C2 pigs, whereas the ∆ADFI independent of duration post-Ch (irreparable portion of feed intake) was significant in C1 pigs only (P < 0.05). Moreover, the time for recovery of ADG and ADFI after Ch was significant in pigs belonging to C1 and C2 (P < 0.05). Control F showed reduced ADG compared with Ct-M, and Ch-F showed reduced ADFI compared with Ch-M (P < 0.05). Moreover, the irreparable portion of ΔADG was 4.8 higher in F (−187.7; P < 0.05) compared with M (−39.1; P < 0.05). There are significant differences in growth performance response to CM based on cluster and sex. Furthermore, bacterial lipopolysaccharide appears to be an appropriate noninfectious model for immune stimulation and growth impairment in pigs.

Formulating Diets for Improved Health Status of Pigs: Current Knowledge and Perspectives

“…The growth performance response of pigs to respiratory pathogens will be dependent on the agent involved. Two recent meta-analyses showed similar results related to severity of respiratory challenge [ 8 , 9 ]. In general, respiratory diseases were less detrimental to performance than the other immune challenges, which may possibly be due to a greater degree of compensatory growth following respiratory infections [ 77 ].…”

“…While both feed intake and nutrient utilization efficiency influence pig performance, the extent to which reductions in these factors are related to the reduction in performance is dependent on the specific immune challenge [ 8 ]. For example, Rodrigues et al [ 9 ] showed that the reduction in growth in challenged compared with control pigs associated with a reduction in feed intake was 14, 4, 45, 1, and 1% in pigs challenged with enteric pathogens, environmental stressors, bacterial lipopolysaccharide (LPS), respiratory pathogens, and sanitary conditions, respectively. This is important to note as, in experimental environments, several challenge models are used to investigate stimulation of the immune system and the associated effects on outcomes such as growth performance impairment, nutrient requirements, and immune status.…”

“…Another important factor differentially impacting performance response in challenged pigs is the stage of production. For example, the meta-analytical approach of Rodrigues et al [ 9 ] demonstrated that recovery of performance in post-weaned pigs was dramatically influenced by the recovery of feed intake, which was not observed in nursery and grower phases. The authors also reported a more abrupt and greater decrease in both growth and feed intake in younger, lighter pigs compared to older, heavier pigs.…”

“…It should be noted that the period after which LPS is administered may influence the response in growth performance of pigs, since tolerance may occur following multiple injections. A recent meta-analysis conducted by Rodrigues et al [ 9 ] revealed a greater reduction in average daily gain in studies using LPS compared to studies using other challenge models (e.g., respiratory pathogens, low sanitary condition, environmental stress). This is consistent with sepsis and septic shock entailed by LPS administration mainly due to the overt cytokine production [ 85 , 86 ].…”

“…Pastorelli et al [ 8 ] reported in a meta-analysis that the reduction in performance during a LPS challenge was due to a depression in feed intake and not to increased maintenance requirements. More recently, these findings were contradicted by another meta-analytical approach which statistically contrasted different challenge models and showed that maintenance requirements had a substantial contribution to the decreased performance in LPS-challenged pigs [ 9 ]. Indeed, altered AA requirements have been demonstrated in multiple studies in LPS-challenged pigs, including Met [ 69 ], Thr [ 18 ], and Trp [ 65 ], which indicates that nutrient maintenance requirements/utilization efficiency play an important role in the observed reduction in performance.…”