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Effects of acute intravenous trimethylamine N-oxide infusion on plasma and serum markers of liver health, glucose tolerance, and milk production in early lactation cows.

W. A. Myers

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06-23-2020

Abstract:

220
Effects of acute intravenous trimethylamine N-oxide infusion on plasma and serum markers of liver health, glucose tolerance, and milk production in early lactation cows.
W. A. Myers*1, F. Wang1,2, C. Chang1, A. N. Davis1, J. E. Rico1, B. N. Tate1, L. F. Wang1,3, J. W. McFadden1. 1Cornell University Ithaca, NY, 2China Agricultural University Beijing, China, 3Henan Agricultural University Zhengzhou, China.

Choline and carnitine are degraded in the gastrointestinal tract in part to trimethylamine, which is oxidized in the liver to form trimethylamine N-oxide (TMAO). In non-ruminants, TMAO has been implicated in the development and progression of fatty liver, heart and kidney disease, diabetes, and cancer. However, the effects of TMAO in cows required investigation. Therefore, 8 early lactation Holstein cows (30.4 � 6.41 d in milk; 2.88 � 0.83 parity) were enrolled in a study with a 4 � 4 replicated Latin square design. Cows were intravenously infused TMAO at 0 (control), 20, 40, or 60 g/d for 6 d. Washout periods lasted 9 d. An intravenous glucose tolerance test (GTT) occurred on d 5. Blood was collected daily. Milk was collected on d −1, 0, 5, and 6. Urine was collected on d −1 and 6. Plasma TMAO, triglyceride, fatty acid, and glucose concentrations were quantified. A serum liver panel analysis and milk composition were also analyzed. The mixed model included the fixed effects of baseline measurements as a covariate and treatment. Dry matter intake was not modified by treatment. Plasma, milk, and urine TMAO concentrations increased linearly with increasing dose (e.g., 12 to 204 μM in cows infused 0 and 60 g of TMAO/d, respectively; P < 0.01). Majority of TMAO was excreted in urine. Plasma triglyceride, fatty acid, and glucose concentrations were not modified by treatment. Serum albumin, total protein, globulin, total bilirubin, direct bilirubin, aspartate aminotransferase, gamma-glutamyl transferase, and glutamate dehydrogenase concentrations were not modified by treatment. Serum glutamate dehydrogenase concentrations decreased linearly with increasing dose (P < 0.05). Serum GTT glucose and fatty acid concentrations were not modified by treatment. Milk yield and composition (fat, protein, and lactose), energy-corrected milk, and feed efficiency were not modified by treatment. We conclude that the acute intravenous infusion of TMAO does not modify measures of liver health, glucose tolerance, or milk production in early lactation cows.

Keywords: choline, dairy cow, trimethylamine N-oxide.