Effect of organic grain supplementation on activity and rumination time of organic dairy cows

Abstract Text: Organic cows (n = 57) were used to evaluate activity and rumination time of cows fed 3 grain supplementation strategies during the grazing season. Cows were assigned to 1 of 3 replicate supplementation groups: 1) no corn grain supplementation (100% pasture, GRS, n = 19), 2) low corn grain (2.72 kg/head/day, LOW, n = 19), and 3) high corn grain (5.44 kg/head/day, HI, n = 19), and calved during 2 seasons at the University of Minnesota West Central Research and Outreach Center, Morris, from October to December 2012 and March to May 2013. Supplement (organic corn grain and minerals) was fed with a TMR of corn silage and alfalfa haylage, and at least 30% of diet DMI for LOW and HI cows consisted of organic pasture.  Pasture and TMR intake were measured on a group basis, because cows were group fed.  Activity and rumination time (daily and 2-h periods) were monitored electronically using HR-LD Tags (SCR Engineers Ltd., Netanya, Israel) for 125 days.  Activity is reported in “activity units” from SCR DataFlow II software.   The PROC HPMIXED of SAS was used for statistical analysis, and independent variables were season of calving (fall or spring), month of grazing (June to September), parity (1, 2, 3+), breed group, supplementation group and the interactions of month of grazing and supplementation group, breed group and supplementation group, and parity and supplementation group.  Cow and replicate were random effects with repeated measures.  The GRS (1,138) cows had greater (P < 0.05) daily activity than HI (1,001) cows, but were similar to LOW (1,019) cows.  Daily activity was the greatest (P < 0.05) during July (1,258) and least during September (819).  Rumination was not different for the GRS (397 min/d), LOW (384), and HI (370) cows.  Daily rumination was greater (P< 0.05) during September (402 min/d) compared to July (361).  Daily activity increased rapidly from h 6:00 and 8:00 to h 16:00 and 18:00.  From h 18:00 to 20:00, cows had a rapid decline in activity until h 6:00 the next day.  All supplementation groups had the greatest rumination during h 2:00 and 4:00 and the least during h 10:00 and 12:00.  In summary, GRS cows had greater activity, but not greater daily rumination, compared to LOW AND HI supplemented cows.  Monthly activity and rumination patterns of grazing organic cows may have been influenced by the weather and fly populations.

Keywords: activity, rumination, organic