The heat increment in fasting sheep of acetic acid partially neutralized with sodium hydroxide

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Abstract
Three experiments have been carried out in which three sheep with rumen fistulas each received into the rumen an infusion of acetic acid partially neutralized with NaOH. The infusion mixture supplied about 700 kcal/24 h. The results have been compared with the results of 5 experiments (Armstrong and Blaxter, 1957) in which sheep received infusions of acetic acid under similar conditions. Infusion of the partially neutralized acetic acid resulted in a smaller decrease in rumen pH and a higher content of steam-volatile fatty acid in the rumen liquor than when equivalent amounts of the unneutralized acid were given. The presence of the sodium ion in the infusion mixture prevented the development of an acidosis as measured by the CO2-combining capacity of the plasma. Significant increases in the concentrations of ketone bodies and of steam-volatile fatty acids in the blood were still observed. The amounts of nitrogen, ketone bodies and steam-volatile fatty acids excreted in the urine were also significantly raised by the infusion of partially neutralized acetic acid. The increment of heat was computed from oxygen consumption and N metabolism and found to be 44.5 [plus or minus]1.3 kcal/100 kcal partially neutralized acid metabolized. This value did not differ significantly from that obtained with acetic-acid infusions, namely 40.9 [plus or minus] 1.8 kcal/100 kcal acid metabolized.