Methyl and methionine utilization in gestating sows

点击翻译按钮获取中文摘要

Precisely meeting the nutrient requirements of gestating sows is essential to improve sow longevity. By closely matching nutrient requirements with dietary supply, we can reduce feed costs and nutrient losses to the environment, which will improve the sustainability of pork production in Canada. Our working estimates of amino acid requirements for gestating sows were derived from very few empirical studies (except for lysine), and the factorial estimates were based solely on the retention of each amino acid in maternal and fetal proteins. These estimates do not take into account the metabolism of the modern sow (many studies are over 50 years old) or the non-protein' roles of amino acids, which can use up a significant proportion of amino acid supply in both the mother and the fetus. Methionine is one such essential amino acid that has over 50 non-protein roles (methyl donation) in the body, which are important for gene expression, cell membrane formation, energy storage, and healthy hoof development. Through these non-protein' roles, methionine can specifically influence the programming of offspring metabolism and the health and productivity of both the sow and her offspring. My overall hypothesis is that dietary supply of methionine during gestation will influence the partitioning of methionine and methyl groups by altering whole body (maternal + products of conception) protein retention and methyl flux. The specific objectives which will be addressed in this Discovery grant, are to: [1] determine protein and non-protein requirements for methionine and methyl groups during gestation, [2] characterize methionine and methyl group utilization during instances of high methyl demand (i.e. during late gestation), and [3] evaluate the short-term effects of maternal methionine supply on the programming of offspring growth and metabolism, when cysteine is supplied in excess. To address this hypothesis, a series of animal experiments will be conducted using various techniques to determine the dynamics of whole-body (i.e. nitrogen balance) and tissue-specific (i.e. isotope tracer techniques) methionine utilization for protein and non-protein' retention in the sow and her offspring. The growth and metabolism of offspring after weaning will also be examined. In addition to training 2 PhD, 1 MSc, and 4 undergraduate students, this research will produce novel data surrounding the partitioning of dietary methionine between protein and non-protein' fates and will advance the understanding of the biological mechanisms that influence nutrient partitioning in the gestating sow. By quantifying and precisely meeting both the protein and non-protein' methionine needs for gestating sows, we may be able to improve piglet survivability, metabolism, and lifetime growth performance, as well as the longevity and reproductive success of sows.**