[Influence of feeding rumen-protected choline to transition dairy cows. Part 1: metabolism and milk yield].

Objective: The effects of rumen-protected choline (RPC) on energy metabolism and milk production in dairy cows were analyzed.
Material and Methods: Two hundred and ninety-eight primiparous and multiparous cows of a high producing dairy herd (mean daily milk yield: 32 l) were randomly assigned to control or treatment groups and were fed with 0 or 15 g RPC, respectively, (corresponding to 0 and 60 g/d ReaShure®, respectively) from 21 days before expected calving to 21 days postpartum (p. p.). Blood metabolites were determined for either all cows (glucose, β-hydroxybutyrate [BHB]) or randomly (insulin, insulin-like growth factor-1 [IGF-1], non-esterified fatty acids [NEFA]) during the periparturient period. An index for insulin sensitivity (RQUICKI) was calculated and milk production data (dairy herd improvement tests, 100-days-, 305-days-, milk peak yield, colostrum quality) was analyzed. In the statistical analysis, a distinction was made between the feeding groups and between the parity, and their interactions were analyzed.
Results: With the exception of a lower 305-day-milk yield in the treatment group (p < 0.05), the evaluated variables did not show statistically significant differences between the feeding groups and no interactions could be found. In comparison to heifers, multiparous cows had less cases of subclinical ketosis a. p. and p. p. (OR a. p.: 0.178; OR p. p.: 0.310), more of them were above the threshold for somatic cell counts (OR 2.584-3.298), and their milk yields were higher (p < 0.05).
Conclusion and Clinical Relevance: Supplementing RPC did not affect the energy metabolism or the milk production in this herd. Further research in other dairy herds should focus on this topic.