The utilization of acetic, propionic and butyric acids by growing heifers

Differing efficiencies of utilization of acetic, propionic and butyric acids in both fasting and fattening sheep have been demonstrated by Blaxter and his colleagues (Armstrong & Blaxter, 1957a, b; Armstrong, Blaxter & Graham, 1957).I n fasting sheep, when the acids were given singly as the sole source of energy, the heat increment with acetic acid (41 yo of the energy of the metabolized acid) was much higher than that with propionic and n-butyric acids (13 and 16%, respectively).With a mixture (3 : 2) of propionic and n-butyric acids the heat increment was reduced to