Abstract
Pregnancy and early life are critical periods during which environmental factors such as nutrition can affect development. Rumen-protected methionine (Met; RPM) supplementation during the prepartum period improves not only performance but immune responses in dairy cows. We investigated the effects of enhanced maternal supply of Met via feeding RPM on whole-blood in vitro lipopolysaccharide (LPS; 0, 0.01, or 5 μg/mL of blood) challenge and targeted microRNA and mRNA abundance in calf blood polymorphonuclear leukocytes (PMNL). Calves (n = 12/maternal diet) born to cows fed RPM at 0.08% of diet dry matter (DM)/d (MET) for the last 21 ± 2 d before calving or fed a control diet with no added Met (CON) were used. The PMNL were isolated at birth (before colostrum feeding) and d 1 (24 h after colostrum intake), 14, 28, and 50 of age. Maternal blood was collected at −10 ± 1.3 d relative to calving. Cows in the MET group had greater DM intake and lower prepartal haptoglobin concentration. In CON cows, haptoglobin was positively correlated with proinflammatory and host-defense mRNA abundance in CON calves. Except for NOS2 and NFE2L2, abundance of CASP8, MPO, ZBP1, and TNF was lower at birth in MET calves. Interleukin 1β concentration in response to LPS challenge in CON and MET calves was greatest at birth, underscoring the role of this cytokine for lymphocyte activation. Compared with 1 d of age, the interleukin-1β response to incremental doses of LPS was greater at 14 through 28 d, suggesting that the neonatal calf can mount a robust response to inflammatory stimuli. Greater abundance in CON calves of NOS2, CADM1, and TLR2 coupled with lower SELL from 1 through 50 d of age suggested a chronic activation of the PMNL. There was a marked upregulation over time of MIR125b, MIR146a, MIR155, and MIR9 in both CON and MET calves, suggesting that these microRNA could affect gene transcription associated with differentiation and inflammatory function in PMNL. Regardless of maternal diet, the gradual downregulation of MIR223 (the most abundant microRNA in PMNL) is in line with the progressive increase over time in the proinflammatory signature of the PMNL. Data revealed the potential for maternal supply of Met during late pregnancy through either greater DM intake or Met to elicit some changes in PMNL function during early postnatal life, partly through changes in mRNA expression encompassing cell adhesion and chemotaxis, oxidative stress, Toll-like receptor signaling, and Met metabolism.