Smartamine M and MetaSmart supplementation during the peripartal period alter hepatic expression of gene networks in 1-carbon metabolism, inflammation, oxidative stress, and the growth hormone-insulin-like growth factor 1 axis pathways

Peripartal cows likely require greater amounts of Met not only at the tissue and cell level for methylation reactions but also for milk protein synthesis after calving. Thirty-nine Holstein cows were fed throughout the peripartal period (-21 d to 30 d in milk) a basal control (CON) diet (n = 14) with no Met supplementation, CON plus MetaSmart (MS; Adisseo Inc., Antony, France; n = 12), or CON plus Smartamine M (SM; Adisseo Inc.; n = 13). The Met supplements were adjusted daily and top-dressed over the total mixed ration at a rate of 0.19 or 0.07% (dry matter) of feed for MS or SM. Liver tissue was collected on 10, 7, and 21 d for transcriptome profiling of genes associated with Met and glutathione metabolism as well as components of the inflammation, oxidative stress, growth hormone/ insulin-like growth factor-1 axis, and DNA methylation pathways. Data were analyzed using PROC MIXED of SAS (SAS Institute Inc., Cary, NC) with the preplanned contrasts CON versus SM + MS and SM versus MS. The S-adenosylhomocysteine hydrolase (SAHH) gene was the most abundant among all genes evaluated, with overall greater expression in Met-supplemented cows than CON, and in SM than MS. Expression of Met adenosyltransferase 1A (MAT1A) was greater in Met-supplemented cows than CON by 21 d postpartum. A greater overall expression of 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) occurred in Met-supplemented cows than CON. In contrast, the expression of glutathione synthase (GSS); glutamate-cysteine ligase, catalytic subunit (GCLC); and superoxide dismutase 1, cytosolic (SOD1) was lower in Met-supplemented cows than CON. A greater overall expression of nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (NFKB1) and greater upregulation of haptoglobin (HP) on d 7 occurred in Met-supplemented cows than CON. Expression of DNA cytosine-5-methyltransferase 3 alpha (DNMT3A) was greater but expression of DNMT1 was lower in Met-supplemented cows than CON. The response observed in SAHH reflects its importance to Met supplementation during the peripartum period. Despite greater HP expression after calving, the lower expression of glutathione (GSS and GCLC) metabolism genes and SOD1 due to Met reflect a lower oxidative stress and mild inflammatory status. The extent to which changes in expression of DNMT3A and DNMT1 result in epigenetic effects partly responsible for the previously observed enhanced performance in Met-supplemented cows remains to be examined. Increasing the supply of Met as SM or MS can affect expression of genes in the Met cycle to various extents and, hence, the supply of methyl donors such as S-adenosylmethionine and antioxidants such as glutathione. These compounds likely are in high demand during the peripartum period.