EFFECTS OF FEED-INTAKE AND WORK SOME BLOOD METABOLITES IN MASHONA DRAFT OXEN FED A GRASS-LEGUME DIET

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 soil t o a depth of 13 cm for four consecutive hours daily, which resulted in work output of 17.6 MJ per day over 35 days. Work increased plasma ur ea concentration (from 5.74 to 4.63 mmol L-1) and reduced calcium conc entration (1.87 vs. 2.30 mmol L-1). Ad libitum intake of a fibrous die t containing 71 g crude protein and 8.2 MJ of kilogram dry matter decr eased the plasma concentrations of urea but maintained relatively high plasma concentrations of inorganic phosphate compared to restricted f eeding at 0.70 ad libitum. Lactate dehydrogenase and creatine kinase w ere not affected by either work or level of intake.