Abstract
Grazing livestock depend largely upon forages to supply their mineral requirements for optimum health and productivity. Hence, information on within-season variation in the mineral content of forages is important. Twenty-eight tropical grasses grown in plots of 1.25 m x 3.00 m at the Central Experiment Station, Centeno, Trinidad, were cut at four 6-week periods of re-growth in the wet season. They were analysed for N, Ca, P, Mg, K, Na, Cu, Fe, Mn, and Zn contents. There was variation in all grasses among the four cutting dates for all the parameters studied. However, the magnitudes of these variations differed not only among grasses for each nutrient, but also within grasses for different nutrients studied. For the seven Brachiaria species, there were significant (P < 0.05) differences among the cutting dates for N, P, K, and Cu contents. But for the seven Panicum maximum cultivars, there were significant (P < 0.05) differences among the cutting dates for N, Ca, P, Mg, K, Cu, and Mn concentrations. There were significant (P < 0.05) differences among the seven Brachiaria species and among the seven Panicum maximum cultivars for all the nutrients studied with the exception of Fe and Ca, respectively. It is concluded that farmers should attempt to have their forages analysed frequently for essential nutrients in order to provide minerals which are deficient in supplemental form and avoid serious health and productivity problems in their grazing ruminants.
