Potential mineral deficiencies for Ndama cattle grazing Urochloa sp. based tropical pastures in the Bas-Congo province of the Democratic Republic of Congo

in Advances in Animal Biosciences (2011), 2(2), 388

Artificial pastures are used to increase carrying capacity in the wet tropics by supplying higher quality forage (energy and protein) to the animals all year long. Sowing pastures is labour-intensive so ... [more ▼]

Artificial pastures are used to increase carrying capacity in the wet tropics by supplying higher quality forage (energy and protein) to the animals all year long. Sowing pastures is labour-intensive so to be profitable all other possible growth limiting factors, especially minerals, should be alleviated. We studied nutrients intake (energy, protein and minerals) in cattle grazing Urochloa sp. pastures in Western DRC. Three Urochloa ruziziensis and 3 U. decumbens pastures in Kolo-Fuma (Bas-Congo, DRC) were studied. Three Ndama steers and 3 cows grazing each pasture consecutively during the short rainy and dry seasons were followed by handplucking and samples were analysed for energy, crude protein and ash to calculate energy value (fodder units, FU) and digestible crude protein content (DCP) of the diets. NIRS was used on faeces to determine dry matter (DM) intake and ICP-AES to determine mineral content of the diets. Intake levels reached 66 ± 4.3 g kg-1LW0.75, nutritive value of forage was 0.701 ± 0.036 FU and 4.78 ± 1.04 % DCP, allowing daily weight gains > 550 g for steers and > 350 g for cows. P, Ca, Mg, K, Mn & Fe were provided above requirements by the pasture. Na, Cu and Zn were deficient, especially during the short dry season for Cu and Zn. U. ruziziensis pastures tended to provide more minerals, especially during the rainy season. A mineral supplement providing Na, Cu and Zn is required to reach the daily weight gains allowed by energy and protein supplies. The supplement could reasonably be similar for U. decumbens and U. ruziziensis pastures, but the dry season formula should provide more Cu and Zn than the rainy season formula [less ▲]

The effect of pasture utilization on the defoliation of grass species by steers grazing a tropical savanna woodland during the dry season

in Advances in Animal Biosciences (2010), 1

The relationship between grazing pressure and differences in the defoliation rate of grass species is not well understood for tropical savannas even though it is likely to have a substantial influence on ... [more ▼]

The relationship between grazing pressure and differences in the defoliation rate of grass species is not well understood for tropical savannas even though it is likely to have a substantial influence on the persistence of preferred species, pasture condition and sustainability of the grazing system. The objective of this study was to examine the relationship between grass species characteristics and their defoliation rate in a paddock under increasing levels of utilization. Nine steers grazed a Eucalyptus savanna woodland for 14 days. Total pasture utilization reached 70% on day 13. The results confirm that with increasing pasture utilization, the defoliation rate of grasses varied among species. Bothriochloa pertusa (Bp) was the preferred species, with the highest levels of utilization after 5, 7 and 13 days. This species had the highest leaf/stem ratio and basal area (P<0.05), and intermediate stem tensile resistance, stem density, bulk density and plant height. These characteristics probably allowed the steers to achieve high nutrient intake rates. The steers avoided B. ewartiana possibly due to its tough stems and low leaf/stem ratio. In this tropical pasture the steers heavily grazed the preferred species at low to intermediate levels of overall pasture utilization (10 to 38%). In order to increase the utilization of less preferred species it was necessary to achieve high levels of pasture utilization (60 to 70%). [less ▲]