Threonine requirement increases in late pregnancy

The metabolism in early pregnancy focuses on development of maternal body tissue. In late pregnancy fetal, and mammary growth increases the demand for nutrients. This change in metabolic focus is hypothesized to result in a higher requirement for amino acids during late pregnancy (3 rd trimester) compared to early pregnancy (1 st trimester). The threonine (THR) requirement was determined using the indicator amino acid (IAA) oxidation method in six multiparous sows. Sows received diets ranging from 60 to 150 % of the current recommended THR intake of 10 gd −1 based on BW, expected pregnancy gain and litter size. L[1‐ 13 C]phenylalanine was given orally in 8 ½‐hourly meals as IAA and expired 13 CO 2 was quantified. Data was analyzed with a nonlinear Mixed model. Sow BW gain and reproductive performance was similar to commercial standards. There was a 2 fold difference in THR requirement. The THR requirement in early pregnancy was no more than 6.1 gd −1 (R 2 =0.56) and in late pregnancy no less than 13.6 gd −1 (R 2 =0.59). The THR requirement of the sow is substantially higher in late pregnancy than currently recommended. Nutritional regimes in pregnancy should account for changes in AA requirement to reduce the risk of overfeeding AA in early pregnancy and underfeeding AA in late pregnancy. Funding: AB Pork, ON Pork, AB Livestock Industry Development Fund, ACAAF, Ajinomoto Heartland.