Effect of rumen protected choline supplementation on digestibility, rumen activity and milk yield in lactating Friesian cows

Abstract

Twelve lactating Friesian cows at 2nd to 5th lactating season, with body weight of 500±15 kg were fed a basal ration consisting, on a dry matter (DM) basis, of 40% concentrate feed mixture + 40% fresh berseem + 20% rice straw supplemented with rumen-protected choline (RPC) in the form of choline chloride at levels of 0, 15 and 30 g/head/day. The cows were used 8 weeks after calving in a complete switch-back design. The digestibility coefficients and nutritive values significantly increased (P<0.05) with RPC. Rumenprotected choline supplementation increased (P<0.05) the intake of total digestible nutrients (TDN) and digestible crude protein (DCP), but decreased plasma cholesterol and triglyceride concentrations (P<0.05). The pH, TVFA and NH3 -N concentrations of rumen liquor was not significantly (P>0.05) affected by RPC supplementation. Rumen-protected choline supplementation led to increased actual milk yield by 1.32 and 2.24 kg/head/day or 8.75 and 14.85%, and 4% fat corrected milk (FCM) by 1.55 and 2.60 kg/head/day or 10.86 and 18.31% for 15 and 30 g RPC compared with un-supplemented RPC, respectively (P<0.05). The contents of fat and total solids (TS) and the yield of all milk constituents except ash increased significantly (P<0.05) with RPC supplementation. Rumen-protected choline supplementation decreased the quantities of DM, TDN and DCP per kg 4% FCM (P<0.05). The feed cost per kg 4% FCM decreased, but the average income of milk yield increased by 3.11 and 5.20 LE or 10.94 and 18.28% for 15 and 30 g RPC compared with un-supplemented RPC, respectively (P<0.05). It could be concluded that rumenprotected choline supplementation at 30 g/head/day to lactating Friesian cows improved digestibility, milk yield and composition, feed conversion, and economic efficiency.