Methyl and methionine utilization in gestating sows

精确满足妊娠母猪的营养需求对于提高母猪寿命至关重要。通过将营养需求与膳食供应紧密匹配，我们可以降低饲料成本和营养向环境的损失，这将提高加拿大猪肉生产的可持续性。我们对妊娠母猪氨基酸需求量的工作估计来自于极少数经验研究（赖氨酸除外），析因估计仅基于母体和胎儿蛋白中每种氨基酸的保留。这些估计没有考虑到现代母猪的代谢（许多研究都超过50年）或氨基酸的非蛋白质作用，这可能会消耗母亲和胎儿中相当大比例的氨基酸供应。蛋氨酸是一种必需氨基酸，在体内具有超过50种非蛋白质作用（甲基捐赠），对基因表达，细胞膜形成，能量储存和健康的蹄发育非常重要。通过这些非蛋白质的作用，蛋氨酸可以特异性地影响后代代谢的程序以及母猪及其后代的健康和生产力。我的总体假设是，妊娠期蛋氨酸的饮食供应将通过改变全身（母体+妊娠产物）蛋白质保留和甲基通量来影响蛋氨酸和甲基基团的分配。本发现补助金将涉及的具体目标是：[1]确定妊娠期间蛋氨酸和甲基的蛋白质和非蛋白质需求量，[2]描述甲基需求量高时蛋氨酸和甲基的利用情况（即妊娠后期），[3]评价母体蛋氨酸供应对后代生长和代谢规划的短期影响，当半胱氨酸过量供应时。为了解决这一假设，将使用各种技术进行一系列动物实验，以确定母猪及其后代中蛋白质和非蛋白质保留的全身（即氮平衡）和组织特异性（即同位素示踪技术）甲硫氨酸利用的动态。还将检查断奶后后代的生长和代谢。除了培养2名博士，1名硕士和4名本科生外，这项研究还将产生围绕蛋白质和非蛋白质命运之间饮食蛋氨酸分配的新数据，并将促进对影响妊娠母猪营养分配的生物学机制的理解。 通过量化并精确满足妊娠母猪对蛋白质和非蛋白质甲硫氨酸的需求，我们或许能够提高小猪的存活率、代谢和终生生长性能，以及母猪的寿命和繁殖成功率。

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.