The effect of a prenatal immune challenge on offspring skeletal muscle characteristics in the longissimus dorsi of weaned pigs

Authors: DOBBINS, THOMAS - Texas Tech University; LEGAKO, JERRAD - Texas Tech University; FERNISS, LUKE - Texas Tech University; WESLEY, KAITLYN - Texas Tech University; JOHNSON, BRADLEY - Texas Tech University; PETRY, AMY - Texas Tech University; Broadway, Paul; Sanchez, Nicole

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 4/17/2023
Publication Date: 11/1/2023
Citation: Dobbins, T.W., Legako, J.F., Ferniss, L.K., Wesley, K.R., Johnson, B.J., Petry, A.L., Broadway, P.R., Sanchez, N.C. 2023. The effect of a prenatal immune challenge on offspring skeletal muscle characteristics in the longissimus dorsi of weaned pigs. Journal of Animal Science Supplement.

Interpretive Summary:

Technical Abstract: An insult to the health status of an animal is associated with reduced skeletal muscle growth and overall production. Furthermore, an immune challenge to a gestating dam may inhibit pre- and post-natal muscle growth of the offspring. The objective of this study was to determine if the administration of lipopolysaccharide (LPS) to gestating sows would alter muscle characteristics of the longissimus dorsi (LD) in piglets after weaning. Pregnant Camborough sows were randomly assigned to receive LPS (LPS; n = 7) at a dose of 2.5 µg/kg BW or saline (CON; n= 7) on 78 ± 1.8 d of gestation. At weaning (21 ± 1.3 d of age), barrows (CON n = 17; LPS n = 17) from each sow were selected to receive a secondary LPS challenge. Following the secondary challenge, barrows were euthanized (31 ± 1.3 d of age), and both LD were collected. The left LD was weighed, measured for circumference at the cranial, middle, and caudal portion of the muscle, and length. Two samples from the right LD were embedded in OCT for histological analyses. Morphometric, fiber type count, primary myofiber clustering, and satellite cell counts were analyzed using the MIXED procedure of SAS 9.4 with a main effect of prenatal treatment and covariate of body weight. The proportion of fiber types between treatments was analyzed by nominal logistic regression using the GLIMMIX procedure of SAS 9.4. There were no differences (P = 0.248) between any morphometric measures. The average diameter for myosin heavy chain (MHC) type 1 and 2B/X was increased (P = 0.048) in LPS offspring compared with CON offspring. Average cross-sectional area (CSA) was increased (P = 0.030) in MHC 2B/X fibers and tended to be increased (P = 0.080) in MHC 1 fibers of LPS treated offspring. The calculated total myofibers within the LD was increased (P = 0.032) in CON offspring compared with LPS. The proportion of myofibers differed (P = 0.046) between treatment groups where LPS offspring had a greater percentage of MHC 2B/X fibers. The diameter, CSA, and total CSA of MHC 1 and MHC 2A clusters was increased (P = 0.001) in LPS offspring compared with CON. There were no differences (P = 0.186) between treatment groups for total nuclei, MYF5, PAX7, or dual positive nuclei. These results implicate a reduction in secondary myogenesis following an immune challenge to the dam, with a rescue response of increased hypertrophy of MHC 1 and 2B/X myofibers post weaning. However, due to the reduction in total myofibers, there is a high likelihood that the LPS impacted offspring would have a reduction in growth parameters such as ADG, feed to gain ratio, and lean skeletal muscle accretion.