137 Impacts of maternal nutrition during gestation on second parity F2 offspring growth and metabolism.

Abstract Maternal nutrition affects metabolism and growth of first- and second-generation offspring, but it is unclear if these effects differentially influence offspring of subsequent parities. We hypothesized that over- or restricted-feeding granddams would influence metabolism and growth of second parity, second generation offspring (F2-2). Pregnant, multiparous Dorset ewes (F0, n = 46) were fed 100% (CON), 60% (RES), or 140% (OVER) of NRC requirements from gestational d 30 until parturition. The resulting F1 ewes (n = 37) were bred to generate the first parity F2 generation (F2-1). The following year, F1 ewes (n = 30) were bred to the same rams to generate second parity F2 offspring (n = 58; CON F2-2: n = 6 ewes, 12 rams, RES F2-2: n = 6 ewes, 12 rams, OVER F2-2: n = 9 ewes, 13 rams). The F2-2 offspring were fed a control diet and grouped according to granddam diet. Body weights of the F2-2 offspring were recorded weekly from birth (d 0) to d 28, every 14 d until d 126, and every 28 d until d 266. Morphometric measurements were collected at d 0 and 120. Body condition scores (BCS) were collected at d 120. Blood samples were collected on d 0, 7, 14, 56, 210, and 266 and analyzed for leptin concentrations. The F2-2 offspring underwent a fasted intravenous glucose tolerance test (IVGTT) at d 133.3 ± 0.17 and blood samples were analyzed for glucose and insulin concentrations. Rams were necropsied at d 284 ± 0.23 for tissue collection. Data were analyzed with R Studio with P ≤ 0.05 considered significant and 0.05 < P ≤ 0.10 considered a tendency. Granddam diet and offspring sex were included in the model with animal ID as a random effect where appropriate. On d 210 and 238, CON F2-2 tended to weigh 6.8% and 6.3% less, respectively, than OVER F2-2 (P = 0.07) but not RES F2-2 (P ≥ 0.15). Crown rump length and heart girth were not influenced by granddam diet at birth or at d 120 (P ≥ 0.92). Granddam diet did not influence leptin concentrations at any timepoint (P = 0.48). Diet did not affect glucose (P = 0.90) or insulin concentrations (P = 0.90) during IVGTT. Glucose (P = 0.96) and insulin (P = 0.59) AUC, and insulin first phase response (P = 0.92) were not influenced by granddam diet. At necropsy, granddam diet did not influence organ weights (P > 0.11). However, CON F2-2 rams tended to 5.9% and 5.6% less BCS than RES F2-2 rams (P = 0.07) and OVER F2-2 rams (P = 0.10). Overfed and restricted granddam diet may increase body weight and BCS of F2-2 offspring but does not appear to cause metabolic alterations.