Study On The Measurement Of Energy Metabolism With A Sulfur Hexafluoride Tracer Technique In Holstein Cows

Two experiments were conducted to determine the heat production in Holstein cows, and the yield of CH₄ and CO₂ were determined by SF6 tracer technique, C,N and energy balance were also calculated. Results detected with SF6 tracer technique were compared with the results of respiration calorimetry chamber to establish the availability of SF6 tracer technique, and effects of monensin on energy metabolism of Holstein cows were investigated by SF6 methods.In experiment 1, 4×4 Latin square design was conducted to establish and confirm the SF6 technique of predict heat production on Holstein breeding cattle. The four groups were divided by different breeding levels of daily gain at 700 g, 500 g, 300 g and 0 g. CH₄ and CO₂ production and HP were determined by respiration calorimetry chamber and SF6 tracer technique at the same time. The results of experiment 1 showed: There were no difference between the results of SF6 tracer technique and Respiration calorimetry chamber (P>0.05) in CH₄ yield. CO₂ yield and HP in 0g/d group determined by SF6 tracer technique were significantly higher than that of Respiration calorimetry chamber (P<0.05). In conclusion, SF6 tracer technique was an efficient method to predict CH₄,CO₂ yield and HP on Holstein cows. CH₄ yield and HP were have significantly differences at different feeding levels (P<0.05), and HP was increased with the increase of feeding levels (P<0.05). There were significantly impacted on apparent deposition rate of metabolic and intake energy and digest and intake nitrogen (P<0.05), which were improved with the increase of feeding levels (P<0.05).In experiment 2, ten Holstein cows were divided into 2 treatments randomly to determine the energy metabolism on Holstein cows by SF6 tracer technique. The two treatments were control and Monensin group (200mg). The results of experiment 2 showed: monensin has significantly reduced yield of CH₄ and CO₂ (P<0.05). Milk energy/gross energy, milk production and energy were improved by monensin obviously (P<0.05). CH₄ energy/gross energy was reduced by monensin obviously(P<0.05).In conclusion, SF₆ tracer techenique was an effective method to determine the energy metabolism under certain condition.