N-carbamoylglutamate supplementation in late-gestation dairy cows is associated with increased newborn weight and improved nutrient supply in the placentome

Abstract

Background N-carbamoylglutamate (NCG), a structural analog of N-acetylglutamate that is essential for endogenous arginine synthesis, has unique advantages, including low rumen degradability, low cost, and a lack of negative effects on intestinal absorption of dietary histidine and lysine. Information is limited on the effect of dietary NCG on the reproduction performance of the late-gestation dairy cows. The objective of this study was to investigate whether supplementation of NCG to cows during late gestation alters uteroplacental tissue nutrient transporters, calf metabolism and newborn weight. Results Thirty multiparous Chinese Holstein cows were used in an experiment with a randomized complete block design. During the last 28 d of pregnancy, cows were fed a diet without (CON) or with NCG (20 g/d/cow). The mRNA expression of genes related to arginine, glucose, and fatty acid transporters, angiogenesis factors and the mTOR pathway in the placentome were analyzed. Blood samples of calves were collected for analysis of plasma parameters, amino acids, and metabolites. The newborn weight (P < 0.01) and plasma arginine concentrations (P = 0.07) were higher in NCG calves than in CON calves. The mRNA expression of genes involved in glucose transport, angiogenesis and the mTOR pathway in the placenta was upregulated (P < 0.01) in NCG-supplemented cows. In addition, 17 significantly different metabolites identified were mainly involved in arginine and proline metabolism; alanine, aspartate and glutamate metabolism and the citrate cycle. Conclusions These results suggest that the increased expression of angiogenesis factors and glucose transporters and the activation of mTOR signaling pathways in the uteroplacenta that occurs through changes in gene transcription under NCG supplementation may be contribute to an increased nutrient supply and improved amino acid metabolism and urea cycling in the fetus.