Management strategies for forage rape (Brassica napus L. cv Goliath): Impact on dry‐matter yield, plant reserves, morphology and nutritive value

Abstract

Limited information is available on the grazing management principles of forage rape (Brassica napus L.), particularly in relation to grazing height and intensity and the impact of these on dry-matter (DM) yield and nutritive value. A glasshouse study was undertaken to investigate the effect of three defoliation heights (plant height at harvest; DH: 40, 70 and 90 cm; L, M and H DH respectively) and three defoliation intensities (height at which plants were cut; DI: 5, 20 and 35 cm of residual height; H, M and L DI respectively) on forage rape (cv Goliath) yield and nutritive value at two harvests (harvest 1, H1 and harvest 2, H2), and the impact of nitrogen (N) and water soluble carbohydrate (WSC) reserves on regrowth. Increasing DH from L to H increased estimated total DM yield (H1 plus H2) from 0.5 to 4.6 t DM/ha but DI did not affect yield. Dry-matter yield was optimized at 90 cm DH, but greater nutritive value was achieved by harvesting at lower levels of DH. Despite high in vitro DM digestibility (IVDMD; 852-889 g/kg), harvesting at 90 cm DH could not meet the protein requirement of lactating dairy cows and harvesting at lower levels risks nitrate poisoning. Our results indicate the optimum DH may be between 70 and 90 cm DH, and 20 and 35 cm DI, which requires further studies.

A manifold response of forage rape to combined heat wave and drought under current and elevated CO2

“…Oilseed rape is an economically important crop, grown for seed oils and animal feed (He et al., 2017). Rapes are the promising forage, characterized by high yielding and nutritive value (Dillard et al., 2019; Islam et al., 2020), its global production is constantly increasing (Beta & Isaak, 2016). Rapes are relatively sensitive for drought and temperature increases (He et al., 2017), heat stress has been shown to increase oxidative stress in forage rape seeds and to reduce seed vigour and quality (Rashid et al, 2018a; Rashid et al, 2020).…”

Napier grass (Pennisetum purpureum Schum) management strategies for dairy and meat production in the tropics and subtropics: yield and nutritive value

“…This suggests that increasing HI from 60 to 120 days may change chemical composition at a slower rate compared to HI from 14 to 56 days in Napier grass. The sharp decline in CP from 14 (or 28) to 56 days of HI is likely due to the mobilisation of N [and water-soluble carbohydrate (WSC)] from the leaf for plant development ( Islam et al., 2012 ) or regrowth ( Islam et al., 2020 ), which ultimately increases the fibre and reduces ME content. These results suggest that a better harvest management strategy is required to optimise the nutritive value of this grass for milk or meat production.…”

“…Therefore, investigation on the impact of leaf stage-based frequent cut and carry on regrowth on Napier grass is essential to maintain both yield and quality of this grass. In addition, information on the impact of defoliation height (plant height at harvest) and severity (height from ground level at which plants are cut) of this grass is essential, as they affect subsequent regrowth ( Islam et al., 2020 ). Moreover, research to quantify how much trade-off between leaf and stem (or yield and quality) is also required, as there is no information on this issue for Napier grass.…”

Fluxos energéticos e reservas orgânicas de plantas forrageiras

“…The concentration of reserve compounds in each compartment of the plant is commonly used to express assimilate fluxes. However, the relative importance of plant parts as reserve organs can vary depending on the assimilated concentration and mass accumulation of the storage organs (Islam et al, 2020).…”