Impact of Mycoplasma hyopneumoniae and Lawsonia intracellularis on the performance of pigs divergently selected for feed efficiency

Abstract

Feed efficiency (FE) is a valuable trait, yet how genetic selection for enhanced FE affects other processes such as response to disease is unknown. Disease from endemic respiratory and enteric pathogens such as Mycoplasma hyopneumoniae (Mh) and Lawsonia intracellularis (LI) are common in swine production. Therefore, the aim of this study was to examine if pigs selected for high vs. low FE based on residual feed intake (RFI) respond differently to a dual respiratory and enteric challenge. Pigs selected for low RFI (LRFI, high FE) are considered more FE compared to their high RFI (HRFI, low FE) selected counterparts. Using a 2 × 2 factorial design, 25 littermate pairs from the HRFI and 25 littermate pairs from the LRFI line (barrows, 50 ± 7 kg BW) were selected, with one pig from each pair assigned to individual pens in either the challenge or the nonchallenge (control) rooms (n = 25 barrows/line/challenge). On days post inoculation (dpi) 0, the challenged pigs were inoculated with LI and Mh (MhLI). Feed intake, BW, fecal swabs, and serum samples were collected and recorded weekly for 42 d. On dpi -2 and 47, 14 littermate pairs (n = 7 barrows/line/challenge) were utilized for initial and final body composition scans using dual-energy X-ray absorptiometry to calculate longitudinal whole body tissue accretion rates for lean, protein, fat, and bone mineral content. Serum antibody levels and fecal shedding of LI were used to confirm infection. Control pigs remained negative by all measures during the 6-wk trial and MhLI inoculated pigs were confirmed positive via serological antibody responses by dpi 14 for LI and Mh. There were no interactions between RFI line and challenge status for any overall performance parameter (P > 0.05). The 6-wk MhLI challenge resulted in a 17% reduction in ADG, a 12% reduction in ADFI, and a 7% reduction in G:F vs. Controls (P < 0.05). In addition, compared to the Control pigs, MhLI challenge reduced lean, protein, and lipid accretion rates by 16% (P < 0.05). Genetic selection for high FE resulted in decreased ADFI and increased G:F (P < 0.01), but did not impact ADG or tissue accretion vs. low FE pigs. Collectively, these results demonstrate that a dual enteric and respiratory pathogen challenge reduced ADG, ADFI, G:F, and tissue accretion in growing pigs. Further, there was no evidence that selection for enhanced FE based on RFI index affects response to disease.

The effects of zinc amino acid complex supplementation on the porcine host response to Lawsonia intracellularis infection

“…The dose given to animals was chosen to induce subclinical disease to better mimic field conditions. Subclinical L. intracellularis infection does reduce production performance but may require a larger number of animals to reach statistical significance in a study [ 8 , 20 ]. Although significant differences in performance were not observed with challenge, L. intracellularis infection was successfully reproduced as confirmed by macroscopic and microscopic lesions, L. intracellularis specific IHC in ileum tissue and antigen specific serum antibody response.…”

Metabolic adaptation of pigs to a Mycoplasma hyopneumoniae and Lawsonia intracellularis dual challenge1

“…The impact of a 42-d MhLI dual challenge on performance of Yorkshire pigs from lines that were divergently selected for RFI has been previously reported (Helm et al, 2018). For the current study, a subset of 24 barrows (48.1 ± 6.7 kg BW), 6 littermate pairs from the low RFI (LRFI) line and 6 pairs from the high RFI (HRFI) line, were randomly selected and confirmed seronegative by ELISA for Mh and LI antibodies.…”

“…In grow-finish pigs, Mycoplasma hyopneumoniae (Mh) and Lawsonia intracellularis (LI) are 2 pathogens that significantly contribute to respiratory and enteric disease, respectively, in the United States (USDA, 2012). These 2 pathogens, alone or in tandem with other infectious agents, reduce average daily gain, lean accretion, and FE (Ciprian et al, 2012;Paradis et al, 2012;Helm et al, 2018). However, the metabolic basis of these reductions in performance beyond reduced feed intake has been poorly characterized.…”

“…Additionally, there is concern that intense selection for production traits such as high FE may alter the pig's ability to allocate resources during times of stress (Rauw, 2007). Previous research has demonstrated that pigs that differed in FE based on divergent selection for residual feed intake (RFI) performed similarly during pathogen challenge (Dunkelberger et al, 2015;Helm et al, 2018) or low RFI pigs performed better under unsanitary conditions (Chatelet et al, 2018).…”

“…Therefore, the aim of this study was to characterize the impact of a Mh and LI (MhLI) dual challenge on the metabolism of grow-finish pigs divergently selected for RFI. We hypothesized that a partial cause of the reduction in performance observed during this MhLI dual challenge (Helm et al, 2018) was a result of greater oxidative stress and skeletal muscle proteolysis, the latter of which would allow for mobilization and allocation of resources to the immune system over lean tissue accretion and growth.…”