Estimation of 24-h energy expenditure in dairy cows using the 13C bicarbonate dilution method

摘要

The interest in pasture-based dairy production systems increases because they can be economically attractive and environmentally friendly (Peyraud et ah, 2010). However, high yielding dairy cows are not able to cover their nutritional demands just bygrazing, and they need additional energy to express their genetic potential for milk production (Kolver and Muller, 1998). So far available data about energy requirements of grazing dairy cows are limited due to the lack of suitable measurement methods.The 13C bicarbonate dilution technique combined with an automatic blood sampling system allows the estimation of energy expenditure (EE) in grazing cows over a 6 h period (Kaufmann et ah, 2011). In order to evaluate if EE measured for 6 h can be extrapolated to 24 h an experiment was conducted recording C02 production, physical activity and feeding behavior during three 6-h periods per d in dairy cows grazed full-time.