PSVIII-25 - Investigating the effects of poor maternal nutrition on F2 offspring growth, residual feed intake, and glucose tolerance

Abstract: Poor maternal nutrition impairs F1 offspring growth independent of changes in feed efficiency and glucose tolerance. To determine if poor maternal nutrition in F0 ewes contributes to F2 offspring growth, feed efficiency, and glucose tolerance, multiparous Dorset ewes (F0; n = 46) pregnant with twins were fed 100%(control), 60%(restricted) or 140%(over) of NRC requirements from d 30 of gestation until parturition. At 16 to 19 mo of age, female F1 (n = 37) offspring were bred to one of two related Dorset rams to generate F2 offspring, identified as CON-F2 (n = 12 ewes; 6 rams), RES-F2 (n = 7 ewes; 13 rams), or OVER-F2 (n = 13 ewes; 9 rams), corresponding to diets of the granddam. F2 offspring body weight (BW) was measured weekly from birth (d 0) to d 28 and every 14 d until d 252. From d 0 to 70, granddam diet did not influence F2 BW (P ≥ 0.18). However, from d 84 to d 154, RES-F2 tended to be 9.42% lighter than CON-F2 with OVER-F2 intermediate (P ≤ 0.08), and from d 224 to d 252 RES-F2 tended to be 6.47% and 6.29% lighter than CON-F2 and OVER-F2, respectively (P ≤ 0.07). Overall, F2 rams were 8.36 kg heavier than F2 ewes (P < 0.0001). At d 133±0.28 an intravenous glucose tolerance test (0.25 g/kg BW of a 50% dextrose solution) was performed. Glucose and insulin concentrations were determined using commercial kits. Granddam diet did not influence glucose or insulin average or baseline concentrations, area under the curve, first-phase response, or ratio (P ≥ 0.52). However, granddam diet influenced glucose peak response in rams, where CON-F2 rams (297 ± 16.5 mg/dL) had greater glucose peak compared with RES-F2 rams (239 ± 11.2 mg/dL; P = 0.05). At d 167±0.33, daily intake of a complete pelleted feed was recorded using Super SmartFeeders over a 77-day feeding period. A treatment by sex interaction was detected for F2 offspring residual feed intake (RFI; P = 0.08) where CON-F2 ewes (0.31 ± 0.12 kg/d) tended to be less feed efficient than CON-F2 rams (-0.45 ± 0.20 kg/d) and RES-F2 rams (-0.20 ± 0.13 kg/d). Alternately, OVER-F2 ewes (0.16 ± 0.13 kg/d), OVER-F2 rams (0.02 ± 0.15 kg/d), RES-F2 ewes (-0.06 ± 0.18 kg/d), and RES-F2 rams were all of similar (P ≥ 0.34) feed efficiency. Rams were euthanized at d 285±0.93 and body morphometrics, and organ weights were collected. No effect of granddam diet (P ≥ 0.25) on F2 ram morphometric measurements, organ weights, or muscle weights (P ≥ 0.15) were detected at time of necropsy. These data indicate that nutrient restriction during gestation decreases F2 offspring BW independent of RFI and glucose tolerance.