Organic dairy cows that consume 100% pasture have lower production but were more profitable because of higher feed costs for supplemented cows, reported researchers at the University of Minnesota during JAM 2013.
The work by B.J. Heins, J.C. Paulson, M.I. Endres and R.D. Moon used organic cows (n = 96) to evaluate grain supplementation levels during the grazing season (May to September 2012) on production, bodyweight, body condition score (BCS) and profitability of organic dairy cows.
Cows were assigned to one of three replicate supplementation groups, 1) no grain supplementation (100% pasture, GRS, n = 32), 2) low grain (2.72 kg/head/day, LOW, n = 32) and 3) high grain (5.44 kg/ head/day, HI, n = 32). They were calved at the University of Minnesota West Central Research & Outreach Center, Morris, Minn., from October to December 2011 and March to May 2012. Supplement (organic corn and minerals) was fed with a total mixed ration of corn silage and alfalfa haylage, and at least 30% of diet dry matter intake for LOW and HI cows consisted of organic pasture.
Milk production, from daily milk weights, was averaged weekly for cows, and bodyweight and BCS were recorded bi-weekly.
The researchers reported that the GRS (14.6 kg/d) cows had significantly (P < 0.05) lower energy-corrected milk than LOW (16.9 kg/d) and HI (16.5 kg/d) cows; however, the LOW and HI cows were not significantly different from each other. The GRS, LOW, and HI cows were not significantly different for bodyweight across the grazing season; however, GRS (2.98) cows had significantly (P < 0.05) lower BCS than HI (3.15) cows. Milk urea nitrogen was significantly (P < 0.05) higher for GRS (14.3 mg/dl) than LOW (10.1 mg/dl) and HI (7.3 mg/dl) cows.
Income over feed costs was significantly higher (P < 0.05) for the GRS ($3.61/cow/day) cows compared with the LOW ($2.20/cow/day) and HI ($0.38/cow/day) cows, the researchers said.