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Nitrogen Retention for Maternal and Fetal Tissues in the Gestating Sow

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Title: Nitrogen Retention for Maternal and Fetal Tissues in the Gestating Sow
Author: Miller, Emily
Department: Department of Animal Biosciences
Program: Animal and Poultry Science
Advisor: de Lange, C. F. M.Cant, J. P.
Abstract: By more closely meeting the nutrient requirements of gestating sows, we can provide cost feed savings, reduce nutrient excretion, and improve sow longevity. This model is able to predict sow body composition (using sow body weight [BW] and backfat [BF]) and whole body protein deposition (Pd; using energy content of the feed and amount offered). Gestational Pd can be divided into pregnancy- and maternal-associated; the former is well characterized, whereas the latter is not. Maternal Pd is difficult to estimate as it is dependent on energy intake, and parity-specific maternal growth, but may also be under the control of pregnancy-associated hormones. Changes in sow BW and BF, repeated nitrogen (N) balance observations throughout gestation, chemical body composition, and glucose tolerance tests were performed to determine: changes in whole body and maternal Pd at two feeding levels (high and low) across three parities and the influence on sow and litter performance; the accuracy of the NRC (2012) body composition prediction equations; and the hormonal control of maternal Pd in late gestation. Whole body and maternal Pd were consistently greater in gilts and sows on the high feeding level and greater in gilts compared to parity 2 and 3. In gilts, reduced maternal Pd in late gestation, regardless of nutrient intake, suggests inherent physiological control. Sow and litter performance were not adversely affected by gestational feeding level. The prediction of body protein was accurate using the NRC (2012) model; however body lipid was poorly predicted in the current group of sows. Hormonal control of nutrient partitioning during pregnancy was evident as insulin resistance was observed at d 75 and 108 of gestation in gilts, a mechanism to shunt nutrients to the fetus and prepare the sow for the demands of lactation. It is speculated that this insulin resistance cannot be manipulated by dietary intervention, but may decrease with increasing parity. Further long-term sow studies are needed to better define maternal Pd and its determinants across multiple parities, and the underlying cellular mechanisms of insulin resistance in late gestating sows and how the onset and severity is influenced by parity.
URI: http://hdl.handle.net/10214/10900
Date: 2017-06-21


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