M. L. Eastridge1 and X. Qiu
The Ohio State University Department of Animal Sciences
Abstract
Milk from bulk tanks was sampled from eleven Ohio herds during May 2000. The milk was analyzed for conjugated linoleic acid, and the characteristics of the herds, milk yield, and feeding practices were provided via a survey to the farmers. Three of the herds were fed some stored forages at the time of the milk sampling, ranging from 5 to 25 lb/day (as-fed) of corn silage with one of these herds also feeding hay free choice. Grain was fed primarily twice daily, with one herd feeding once and another herd feeding grain three times daily. The herds averaged 43 cows, 50.3 lb/day of milk, and fed 9.8 lb/day of grain. The CLA concentration in the milk was compared to other previously published studies. The overall trend was for increased concentration of CLA in milk with decreasing amount of grain fed (or increasing amounts of pasture consumed). All data points with CLA concentration in excess of 1.0% of fatty acids in milk represented cows that were consuming pasture. Thus, the concentration of CLA in milk appears to be higher for cows grazing pasture than for cows fed stored feeds, and the data from the field study were reflective of the data from other published studies. Additional research is underway to investigate factors that may be affecting the CLA concentration of milk when cows graze pasture.