Evaluating the total mixed ration stability of rumen protected choline products

A technique has been established to determine the TMR stability of rumen-protected (RP)-lysine products, but the TMR stability of RPcholine (RPC) products has not yet been explored. The objective of this experiment was to evaluate the TMR stability of 5 RPC products using a modified technique. Triplicate Ziploc bags containing RPC (equivalent of 1 g of choline chloride [CC]), no RPC (negative control), or unprotected CC (positive control; 1 g of CC) mixed with 200 g of TMR (38% DM) were incubated at room temperature (22°C) and unsealed for 0, 6, 12, and 24 h. At the end of each time point, bag contents were transferred to strainer bags and soaked in 1 L of distilled water for 1 min to solubilize any free CC released from the products. A sample of solution was filtered (0.45 μm) and stored at −20°C until analysis for CC content using a YSI biochemical analyzer. The CC content for samples containing RPC or unprotected CC were corrected for background CC measured in the negative control samples. Recovery of unprotected CC was influenced by TMR incubation time and was not complete (78%, 61%, 59%, and 51% at 0, 6, 12, and 24 h of TMR exposure, respectively). Thus, a correction factor was applied to samples containing RPC to account for unrecovered CC released from the products. Total CC release was calculated for RPC. Data were analyzed using the MIXED procedure of SAS. Means within an incubation time were separated using the Tukey adjustment. At time 0, products C, D, and E experienced minimal CC release (Table 1). Products A and B had a similar release pattern to one another across the 4 time points and were the 2 products with the highest CC release at all exposure times. Product D was the most stable from 6 to 24 h. The modified technique detected vast differences in TMR stability across RPC products over a 24-h period.

Key Words: rumen protected choline, TMR, choline