Plasma under the curve response to 3 different rumen-protected methionine supplements in cows

• Brandon Albaugh, Pre-Veterinary Medicine and Animal Biosciences, University of Delaware

• Tanya Gressley, Animal & Food Sciences, University of Delaware

Methionine is an essential amino acid in short supply for dairy cattle, as cows cannot synthesize it and methionine supplements are degraded in the rumen. This has led to the development of rumen-protected methionine products, which use coatings resistant to rumen microbes for better absorption of methionine. Our main objective is to test 3  rumen-protected methionine products in dairy cattle for their levels of relative methionine bioavailability against DL methionine. We tested this on 4 lactating dairy cows, all previously cannulated, where each cow was given 1 of the 3 RPM products or the control during each experiment period of 48 hours across 4 total periods, giving us a 4×4 unreplicated Latin square experiment. Treatments were given before morning feeding and deposited by the esophageal orifice after being mixed with 600 mL of water. Blood samples were taken via jugular catheters at 0 h, 1 h, 2 h. 3 h, 4 h, 6 h, 9 h, 12 h, 24 h, and 48 h post-infusion and transported in ice containers to our lab. Blood samples were centrifuged at 2000 rpm at 4°C for 20 minutes. Blood plasma was collected via transfer pipettes and transferred into cryovials and stored at -80°C. Feed samples were also taken 3 days per week for Dry Matter Analysis and consistency for feeding. Blood plasma samples were sent to Penn State for analysis of Methionine levels and bioavailability percentage. Our results are yet to be conclusive, but we expect product #2, Smartamine, to perform at around 80% bioavailability and products #1 and #3 to perform at a similar level. These study findings can be used by the ingredient supplier company, Kemin, to develop better RPM products.