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ARS Home » Midwest Area » Lexington, Kentucky » Forage-animal Production Research » Research » Publications at this Location » Publication #278551

Title: Evaluation of a rapid determination of heat production and respiratory quotient in Holstein steers using the washed rumen technique

item KIM, DO - University Of Kentucky
item MCLEOD, KYLE - University Of Kentucky
item Klotz, James
item KOONTZ, ANNE - University Of Kentucky
item FOOTE, ANDREW - University Of Kentucky
item HARMON, DAVID - University Of Kentucky

Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/2012
Publication Date: 7/15/2012
Citation: Kim, D.H., Mcleod, K.R., Klotz, J.L., Koontz, A.F., Foote, A.P., Harmon, D.L. 2012. Evaluation of a rapid determination of heat production and respiratory quotient in Holstein steers using the washed rumen technique. J. Anim. Sci. Vol. 90, Suppl. 3:99.

Interpretive Summary:

Technical Abstract: The objective of this study was to validate use of the washed rumen technique for rapid measurement of fasting heat production (FHP) and respiratory quotient (RQ), and compare this with heart rate (HR) and core temperature (CT). The experiment used 8 Holstein steers (322±30 kg) under controlled temperature (21°C) as follows: 10 d diet adaptation, 1 d measurement of respiratory gases at 1.5×NEm (Unwashed rumen), 1 d measurement of respiratory gases at fasting (Washed rumen), and 7 d for re-establishing intake. Steers were offered alfalfa cubes top-dressed with a mineral pre-mix at 1.5×NEm. At the day of measurement the reticulorumen was washed and refilled with ruminal buffer (NaCl=96; NaHCO3=24; KHCO3=30; K2HPO4=2; CaCl2=1.5; MgCl2=1.5 mmol/kg of buffer) that was gassed with a mixture of 75% N2 and 25% CO2 before incubation in the rumen. Mean daily CT between unwashed and washed rumen were not different (Table 1). Mean daily HR and HP were lower for washed rumen than for unwashed rumen (P<0.001). RQ was lower for washed rumen and there was an interaction (P<0.001) with sampling hour. In order to define the plateau of RQ, dependence of RQ rate and hour on unwashed and washed rumen was fitted by a one-phase decay equation. The plateau of RQ values were calculated at 0.87±0.01 and 0.72±0.01 for unwashed and washed rumen, respectively. The RQ decreased to approximately 0.7, by 8 h after washing the rumen. This approach may provide an alternative to the traditional 48 h fasting time, or measurements made during the third and fourth day after starvation. Applying the washed rumen technique may be more rapid and less stressful means to predict energy required for maintenance in cattle. Table 1. Comparison of washed and unwashed rumen models Item Unwashed Rumen Washed Rumen SEM P -value Treatment (T) Hour (H) T × H CT, °C 36.91 36.91 0.07 ns ns ns HR, beats/min 57.62 45.30 1.01 <0.001 ns ns HP, kJ/kg BW0.75 237.15 167.01 3.67 <0.001 ns ns RQ 0.85 0.73 0.01 <0.001 <0.001 <0.001 Keywords: Fasting Heat Production, Respiratory Quotient, Washed Rumen