PSIV-18 - Poor gestational nutrition impacts sheep offspring growth but not feed efficiency

The objective was to determine the effects of poor maternal nutrition during gestation on growth and feed efficiency of offspring. We hypothesized that body weights (BW) would decrease and residual feed intake (RFI) would increase (reduced feed efficiency) in offspring of restricted- and over-fed ewes. Forty-six multiparous Dorset ewes pregnant with twins were fed 100%, 60% or 140% of NRC requirements from d 30 of gestation until parturition. Offspring are referred to as CON (n = 10 ewes; 12 rams), RES (n = 13 ewes; 21 rams), and OVER (n = 16 ewes; 13 rams), respectively. Lamb BW were measured weekly from birth to d 28 and biweekly until d 252 of age. Starting at d 167±13.6, daily intake of a complete pelleted feed was recorded using a Super SmartFeed (C-lock Inc., Rapid City, SD) over a 77 d- feeding period. Average BW were taken two days before, at mid-point, and two days after the feeding trial period and RFI was calculated for each animal. Rams were euthanized at d 284±12 and body morphometrics, loin eye area (LEA), back fat thickness, and organ weights were collected. From birth to d 252, ram lambs were 5.4 kg heavier (P < 0.001) than ewe lambs. Control ewe lambs were 4.3 kg heavier than RES and OVER (P < 0.05) from birth to 9 months and CON rams were 4.7 kg heavier (P < 0.01) than RES. Rams (-0.17) were more efficient than ewes (0.23; P < 0.01); however, no dietary treatment difference was observed (P ≥ 0.57). No differences in muscle mass, LEA, and adipose deposition were observed (P ≥ 0.41). These data indicate that poor maternal diet during gestation impacts offspring growth but not RFI. Further investigation is warranted to determine if differences in BW are a result of metabolic alterations impacted by poor maternal nutrition during gestation.