Cultivated and native browse legumes as calf supplements in Ethiopia

Abstract

Efficient use of roughages is important for calf management in the Boran pastoral system. Using local legumes as protein supplements may improve fiber utilization and thus be an appropriate intervention. Fruits (pods and seeds) of Acacia tortilis (Forsk.) Hayne subsp. spirocarpa (Hochst. ex A. Rich) Brenan, leaves of A. brevispica (Harms), and cowpea [Vigna unguiculata (L.) Walp] hay were compared with alfalfa (Medicago sativa L.) hay as protein supplements for calves using 2 approaches. Sheep fed native grass hay under confinement were used for a controlled evaluation in growth and metabolism trials. Calves grazing dry-season forage under simulated pastoral management provided in evaluation under field conditions. All supplements increased (P<0.05) nitrogen (N) intake, growth rate, and conversion of dry-matter intake into liveweight for sheep compared to unsupplemented animais. Calf growth and water intake were increased (P<0.05) relative to the control by ail supplements except cowpea hay. When statistically adjusted to a common level of N intake, N retention was similar (P>0.05) among all groups of supplemented sheep. Compared to alfalfa and cowpea diets, tanuinfferous Acacia diets had a negative effect (P<0.05) on true-N digestibility, but this was offset by their positive effect (P<0.05) on reducing loss of urinary N. The A. tortilis diet had a lower (P<0.05) true-N digestibflity than the A. brevispica diet, which was probably influenced by soluble phenolics in pods and seeds. On a nutritional basis these Acacia and cowpea materials art suitable for inclusion in improved feeding systems for Boran calves