Abstract

Two studies were conducted to examine the effects of maternal nutrition during early and mid-gestation on fetal growth. In the first, crossbred heifers were managed for High (H, 0.6 kg/day) or Low (L, 0.1 kg/day) live weight gains from mating until day 140 of gestation. Treatments were then reversed so that effects of nutrition during early gestation were not confounded by differences in maternal live weight at calving. Maternal liveweights (kg, Mean±SE, n=30/group) were (L vs H) 350.6±4.9 vs 394.3±5.3 (P<0.001) at day 140 of gestation and 393.5±5.3 vs 394.4±5.8 (P>0.05) at term. Calf birth weights (L vs H) were 30.9±0.7 vs 29.9±0.8 kg (P>0.05). In the second study, 60 Romney ewes were allocated to three nutritional treatments, 0.5 maintenance (M), 1.0M or 1.5M from days 21 to 101 of gestation. At day 101, ewe liveweights were 45.8±1.4, 56.8±1.4 and 69.1±1.4 kg respectively (P<0.001). Fetal weights at slaughter (day 101 of gestation) were 1249.9±40.6, 1280.8±38.0 and 1379.8±35.2 g respectively (P<0.05). These results indicate that, although the fetus places a relatively small nutritional demand on the dam in early gestation, fetal development can in some situations be influenced by maternal nutrition, particularly when dams are over- rather than under-fed.

K, Cooper, ST Morris, and SN McCutcheon

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 175-177, 1998