256. Modest but Chronic Maternofetal Inflammation During Late Gestation in Beef Cows Reduced the Subsequent Birthweight of Their Calves.

Abstract Maternofetal inflammation causes intrauterine growth restriction (MI-IUGR), which is associated with lifelong deficits in growth and metabolic function for the offspring. However, the effect of long-term, low-dose inflammatory stimulation in beef cattle during late-stage pregnancy is not well understood. Therefore, the objective of this study was to determine if serial bacterial endotoxin challenges to induce chronic, low-grade maternal inflammation would reduce fetal growth and body symmetry in cattle. Angus crossbred cows were randomly assigned to receive a series of eight lipopolysaccharide (100 ng/kg LPS; n = 15) or saline (n = 8) injections every 72 hours, beginning near the end of the second trimester of pregnancy, to produce MI-IUGR (n = 11) and control (n = 6) calves, respectively. Respiration rates and blood profiles were assessed in cows just before and at 12 and 24 hours after each injection. At birth, calf bodyweights and biometrics were measured. Respiration rates were increased (P £ 0.05) in LPS-treated cattle 12 hours post-injection for injections 3 through 8, indicating sustained stress responsiveness. Lymphocyte concentration was decreased (P £ 0.05) in LPS-treated cows at 12 hours following every injection, and platelets were decreased (P £ 0.05) at 12 and 24 hours after all but the final injection. Conversely, white blood cell and monocyte concentration were generally increased (P £ 0.05) in LPS-treated cattle 24 hours after each injection. This indicates a pattern of sustained systemic inflammation across the entire induction period. Additionally, circulating lactate was elevated (P £ 0.05) in the LPS treated cows for the duration of the study, which corresponds with a greater anaerobic glycolysis, but blood pH was only decreased (P £ 0.05) in LPS-treated cows 24 hours after injections 2 and 3. Nevertheless, birth weights in MI-IUGR calf (35.2 ± 1.0 kg) were decreased (P < 0.01) by about 10% compared to controls (39.3 ± 0.8 kg), with no differences in calf body length (96.9 ± 2.9 vs. 97.1 ± 3.2 cm), hip height (73.1 ± 1.1 vs. 72.2 ± 2.9 cm), or crown circumference (47.4 ± 0.8 vs. 44.4 ± 1.8 cm), which illustrates asymmetrical body composition typical of intrauterine growth-restricted newborns. Gestation length tended to be shorter (P = 0.06) for MI-IUGR calves by a modest 2%. These findings indicate that moderate maternofetal inflammation sustained for a long period of time gives rise to impaired fetal growth and hallmark asymmetrical body composition in cattle.