Influence of species, cultivar and cut on the microelement content of grass forages

Abstract

A study was undertaken to determine the influence of species, cultivar, cut and year on the mineral content of forages as related to the requirements of lactating dairy cows. Four species of grass forages represented by nine cultivars were sown in a randomized block designed trial replicated four times. The test included: meadow fescue (MF) - Festuca pratensis (pratense), cultivars #920, #930 and Ensign; orchardgrass (cocksfoot) (OR) - Dactylis glomerata L., cultivars Arctic and Sumas; perennial ryegrass (PR) - Lolium perenne L. cultivar Norlea and tall fescue (TF) - Festuca arundinacea, cultivars Courteney, Barcel and Fawn. The plots were harvested four times in each of two years. Yields were measured for each plot and harvest time and samples were obtained for the determination of dry matter (DM), crude protein (CP) acid detergent fibre (ADF) and microelements: Fe, Mn, Zn and Cu. The TF cultivars tended to out yield the cultivars of other species with Courteney (TF) being higher in DM yield (P ≤ 0.05) than Ensign (MF), Arctic (OG) and Norlea (PR). There were also differences in mineral content among individual cultivars. First cut forages had the lowest content (P ≤ 0.05) of all microelements measured except Zn when compared to third and fourth cut forages. In terms of a lactating cow‘s requirements, the Zn and Cu content of these forages were consistently deficient. It was concluded from the results of this study that the species, cultivar, year and/or cut of forage can impact on microelement content sufficiently to warrant consideration when formulating diets for beef cattle and lactating cow.