Calorimetric facilities for dairy cattle at Ruakura Animal Research Station

A.M. Bryant, J.W. Hughes, J.B. Hutton, R.P. Newth, C.R. Parr, T.E. Trigg and J. Young

Ruakura Agricultural Research Centre, Hamilton

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Proceedings of the New Zealand Society of Animal Production. 1977, 37: 158-162

The open-circuit respiration chambers in operation at Ruakura are briefly described. In eight recovery tests on each of the two chambers, average recovery of CO₂ was 99.93 ± 0.28 and 100.19 ± 0.32%. Six sets of twin cattle in late lactation were used to compare energy utilization of pasture and similar material after partial dejuicing. The twins were split between rations which were fed at two levels, dry matter intake averaging 2.7 and 2.2 kg/100g liveweight. In the 24 energy balances involved, the relationship between energy retention derived from the carbon-nitrogen balance (Y) and respiratory exchange (X) was Y=0.99X + 2.66 (RCV., 11.4%). The linear regression of energy balance, corrected to zero tissue loss, on metabolizable energy (ME) intake indicated an efficiency of utilization of ME for milk and body tissue of 52 ± 4.5% and a maintenance requirement of 524 ± 54 kJ/kg LW^0.75. Ration was without significant effect. In order to achieve the same energy balance, cows at the high level of feeding required 73 ± 32 kJ ME/kg LW^0.75 more than when at the low level.

Keywords: NZSAPAB;

Last Updated 24-08-2000