Abstract
An experiment was carried out to study the effects of intake and work on the concentrations of blood metabolites in 16 mature Mashona oxen. Work consisted of pulling a mouldboard plough penetrating sandy oil to a depth of 13 cm for four consecutive hour daily, which resulted in work output of 1 7 .6 MJ per day over 35 days. Work increased plasma urea concentration (from 5.74 to 4.63 mmol L-1) and reduced calcium concentration (1.87 v 2.30 mmol L-1). Ad libitum intake of a fibrous diet containing 71 g crude protein and 8.2 MJ of metabolizable energy per kilogram dry matter decreased the plasma concentrations of urea but maintained relatively high plasma concentrations of inorganic phosphate compared to restricted feeding at 0.70 ad libitum. Lactate dehydrogenase and creatine kinase were not affected by either work or level of intake.
