Increasing the prepartum dose of rumen-protected choline: Effects on milk production and metabolism in high-producing Holstein dairy cows

Peripartum rumen-protected choline (RPC) supple-mentation is beneficial for cow health and production, yet the optimal dose is unknown. In vivo and in vitro supplementation of choline modulates hepatic lipid, glucose, and methyl donor metabolism. The objective of this experiment was to determine the effects of in-creasing the dose of prepartum RPC supplementation on milk production and blood biomarkers. Pregnant multiparous Holstein cows (n = 116) were randomly assigned to one of 4 prepartum choline treatments that were fed from -21 d relative to calving (DRTC) until calving. From calving until +21 DRTC, cows were fed diets targeting 0 g/d choline ion (control, CTL) or the recommended dose (15 g/d choline ion; RD) of the same RPC product that they were fed prepartum. The result-ing treatments targeted: (1) 0 g/d pre-and postpartum [0.0 & PLUSMN; 0.000 choline ion, percent of dry matter (%DM); CTL]; (2) 15 g/d pre-and postpartum of choline ion from an established product (prepartum: 0.10 & PLUSMN; 0.004 choline ion, %DM; postpartum: 0.05 & PLUSMN; 0.004 choline ion, %DM; ReaShure, Balchem Corp.; RPC1RD,RD); (3) 15 g/d pre-and postpartum of choline ion from a concentrated RPC prototype (prepartum: 0.09 & PLUSMN; 0.004 choline ion, %DM; postpartum: 0.05 & PLUSMN; 0.003 choline ion, %DM; RPC2, Balchem Corp.; RPC2RD,RD); or (4) 22 g/d prepartum and 15 g/d postpartum from RPC2 [prepartum: 0.13 & PLUSMN; 0.005 choline ion, %DM; postpar-tum: 0.05 & PLUSMN; 0.003 choline ion, %DM; high prepartum dose (HD), RPC2HD,RD]. Treatments were mixed into a total mixed ration, and cows had ad libitum access via a roughage intake control system (Hokofarm Group). From calving to +21 DRTC, all cows were fed a com-mon base diet and treatments were mixed into the total mixed ration (supplementation period, SP). Thereafter, all cows were fed a common diet (0 g/d choline ion) un-til +100 DRTC (postsupplementation period, postSP). Milk yield was recorded daily and composition analyzed weekly. Blood samples were obtained via tail vessel upon enrollment, approximately every other day from -7 to +21 DRTC, and at +56 and +100 DRTC. Feed-ing any RPC treatment reduced prepartum dry matter intake compared with CTL. During the SP, no evidence for a treatment effect on energy-corrected milk (ECM) yield was found, but during the postSP, RPC1RD,RD and RPC2RD,RD treatments tended to increase ECM, pro-tein, and fat yields. During the postSP, the RPC1RD,RD and RPC2RD,RD treatments tended to increase, and RPC2HD,RD increased, the de novo proportion of to-tal milk fatty acids. During the early lactation SP, RPC2HD,RD tended to increase plasma fatty acids and & beta;-hydroxybutyrate concentrations, and RPC1RD,RD and RPC2RD,RD reduced blood urea nitrogen concentrations compared with CTL. The RPC2HD,RD treatment re-duced early lactation serum lipopolysaccharide binding protein compared with CTL. Overall, peripartum RPC supplementation at the recommended dose tended to increase ECM yield postSP, but no evidence was seen of an additional benefit on milk production with an increased prepartum dose of choline ion. The effects of RPC on metabolic and inflammatory biomarkers sup-port the potential for RPC supplementation to affect transition cow metabolism and health and may support the production gains observed.

Automated summary

Peripartum rumen-protected choline (RPC) supplementation benefits cow health and production, but the optimal dose is unknown. Increasing the dose of prepartum RPC supplementation may increase postpartum milk yield, but there is no additional benefit from increasing the prepartum dose of choline ion on milk production.