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Subject: search.filters.subject.Maternal nutrition

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    Effect of maternal nutrition during early and mid-gestation on fetal growth : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science (in Animal Science) at Massey University
    (Massey University, 1998) Cooper, Kate
    It is generally assumed that, because the fetus has a small nutritional requirement relative to that of the dam in early gestation, differential maternal nutrition at this time is unlikely to influence fetal growth. Hence the dogma that females in early gestation need not be provided with nutrients additional to those required by comparable nonpregnant females. However, the effects of nutrition during early gestation on fetal and placental growth and development, and hence birth weight, have not been studied extensively. Nor does the current dogma take into account the fact that the placenta has a different pattern of growth from the fetus. Hence this study sought to further examine the effects of maternal nutrition during early and mid-gestation on placental and fetal growth. The first study was conducted over two years, with crossbred heifers managed for High (H, 0.6 kg/day) or Low (L, 0.1 kg/day) liveweight 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. Averaged across years, maternal live weights (kg, Mean±SE, n=60) were (H vs L) 393.5 ± 4.3 vs 362.1 ± 4.3 (P<0.001) at day 140 of gestation and 417.6 ± 4.5 vs 408.7 ± 4.3 (P>0.05) at term. Calf birth weights were 31.1 ± 0.5 vs 31.4 ± 0.5kg and weaning weights (average calf age = 90 ± 14.4days) were 91.3 ± 2.0 vs 89.7 ± 2.0 (both P>0.05). A second study using breeding ewes was designed to determine more directly whether early placental development and fetal growth may be modulated by nutritional manipulation of the female during early and mid-gestation, and so eliminated the potential for the dam to compensate for earlier treatments during late gestation. Mixed-age Romney ewes (average live weight 54.5 ± 0.4 kg), pregnant to a synchronised oestrus, were allocated to three nutritional treatment groups (n = 20/group), Low (L = 0.5 maintenance (M)), Control (C = 1.0M) and High (H = 1.5M) from days 21 to 101 of gestation. Maintenance requirements for a 50 kg ewe were assumed to be approximately 0.9 kg DM/ewe/day (10 MJ ME/day) at a concentration of 11 MJ ME/kg DM. Ewes were weighed weekly, slaughtered at the end of treatment, and fetal and placental measurements recorded. Live weights were significantly (P<0.001) different at slaughter (L, 45.8 ± 1.4 kg; C, 56.8 ± 1.4 kg; H, 69.1 ± 1.4 kg). At day 101 of gestation, measures of fetal and placental growth and development were (C vs H group): Uterus (minus fetus and fluids) (1290.7 ± 67.0 vs 1475.4 ± 64.8 g, P<0.05); fetal weight (1280.8 ± 38.0 vs 1379.8 ± 35.2 g, P<0.05); total placentome weight (631.0 ± 30.7 vs 702.9 ± 29.7 g, P<0.01) and total placentome number (102.6 ± 3.2 vs 93.4 ±3.1 g, P<0.05). Low levels of maternal nutrition did not significantly influence these parameters (L vs C). It is concluded that high levels of maternal nutrition in early and mid-gestation enhance fetal and placental growth and development in sheep, while low levels are without effect compared to ewes fed at maintenance. Thus there may be advantages to high levels of maternal nutrition in early and mid-gestation though the possible effects of compensation in later gestation, as may have occurred in the beef cow trial, are yet to be studied in sheep.
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    Estimation and identifiability for a dynamic model of maternal nutrition and fetal growth in sheep : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Statistics at Massey University, Albany, New Zealand
    (Massey University, 2012) Wang, Leiyan
    The optimal maternal nutrition intake is extremely important in the second half of pregnancy for fetal development in mammals. It affects the health and wellbeing of the offspring. The purpose of this study was to determine the optimal daily nutrition intake for sheep during the second half of their pregnancy, to achieve a pre-determined desirable birth weight for lambs. By achieving the optimal birth weight, the postnatal development of the animals is likely to be improved. In this study, pregnant sheep carrying singletons or twins were considered. There were two levels of nutrition, low and high. Various dynamic mathematical models were proposed to obtain the optimal daily nutrition intake. The model parameters were estimated by weighted least-squares. Bootstrap simulations were used to check the reliability of each estimated parameter. Finally, the optimal daily nutrition intake was obtained by solving the boundary value problems, with pre-determined parameter values. The results suggested that the optimal daily nutrition intake for sheep in the second half of their pregnancy was a constant. For the particular breed of sheep, with target weight 6.5 kg for singletons, the optimal nutrition intake was 1.36 kg of dry matter per day. For twins, with a target weight of 12 kg, the optimal nutrition intake was 1.93 kg of dry matter per day. In addition, a comprehensive and generic ‘black-box’ algorithm was produced using the software MATLAB. It could return the optimal daily nutrition intake for any type of mammals given a time series of fetal weight and maternal nutrition.
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    Ewe size and nutrition during pregnancy : effects on metabolic and productive performance of the offspring : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Turitea, Palmerston North, New Zealand
    (Massey University, 2010) Linden, Danitsja Stephanie van der
    Exposure of the fetus to adverse conditions in utero may result in developmental adaptations that alter metabolism and postnatal growth of the offspring. This thesis investigated the effects of dam size and nutrition during pregnancy on growth, metabolic function and lactational and productive performance of the female offspring to two years of age. Four-hundred and fifty heavy (60.8 kg ± 0.18) and 450 light (42.5 kg ± 0.17) dams were randomly allocated to ad libitum or maintenance nutritional regimens from days 21 - 140 of pregnancy, under pastoral grazing conditions. From one week prior to lambing, all dams were fed ad libitum until weaning. After weaning, female progeny were managed and fed under pastoral conditions as one group. Maternal nutrition during pregnancy affected lamb growth to weaning, however, after weaning lamb growth was affected by dam size. Dam size had no effect on glucose metabolism, adrenal function or fat metabolism in 16-month-old female twin offspring. Dam nutrition during pregnancy had a minor effect on glucose metabolism and no effect on adrenal function or lipolysis, however, it did possibly affect gluconeogenesis and/or glycogenolysis, with increased glucose production in ewes born to maintenance-fed dams. Ewes born to dams fed maintenance showed greater milk production, lactose percentage, lactose and crude protein yield. Ewes born to heavy dams showed greater milk production and lactose yield. Dam size had no effect on reproductive performance of the female offspring. Being born to a larger dam showed no advantages over being born to smaller dams, for number of lambs born and weight of lambs at birth and weaning. ‘Grand’dam maintenance nutrition increased lamb birth and weaning weight and lamb growth rates of the ‘grand’offspring. Ewes born to maintenance-fed dams could have an advantage over ewes born to ad libitum-fed dams in physiological stressful situations in life as their liver may be able to supply more glucose to support their growing conceptus and milk production to increase the chances of survival of their offspring. These results indicate that it is possible to programme the offspring by feeding their dams differently during pregnancy under grazing conditions. With a better understanding of how offspring can be programmed through different maternal nutritional regimens, it may be possible to significantly increase the production potential of the New Zealand ewe population.