At the Centre for Tropical Veterinary Medicine, Scotland, during the summer months of 1987, two adult water buffaloes, two Brahman cattle and two Brahman × Friesian steers walked round a circular track on concrete or through 300 mm deep mud. Average walking speed (m/s) when unloaded, or average walking speed (m/s) when pulling 324 N, energy for walking (J/m/kg) and net mechanical efficiency (%) were 1·05 and 0·81 (P < 0·01), 1·03 and 0·80 (P < 0·001), 1·49 and 3·34 (P < 0·001) and 31·0 and 31·8 for concrete and mud respectively. Energy values were calculated from gaseous exchange measured with an open circuit system.

In Central Nigeria, from September 1991 to May 1992, the energy expenditure of eight Bunaji (White Fulani) bulls was monitored using portable oxygen measuring equipment (modified ‘Oxylog’) when walking, ploughing and harrowing on six soil surfaces ranging from hard, smooth earth to ploughed, waterlogged clay. Average walking speeds (m/s), pulling speeds (m/s) and energy cost of walking (J/m/kg) varied from 0·97 to 0·65, 0·55 to 0·47 and 1·47 to 8·58 respectively. Net mechanical efficiency averaged 31·4% and was unaffected by ground surface.

The energy cost of walking for the Bos indicus cattle on smooth ground (1·47 J/m/kg) in this trial was less than that previously reported for Bos taurus (1·80 J/m/kg) and the reported average value for cattle (Bos indicus and Bos taurus) on treadmills (2·09 J/m/kg). The implications for practical agriculture of the higher levels of energy expenditure for walking in muddy conditions are discussed.