Performance responses of lambs of various ages to Italian ryegrass (<i>Lolium multiflorum</i>) fertilized with various levels of nitrogen

Abstract

Italian ryegrass (Lolium multiflorum cv. Midmar) is often fertilized with high levels of nitrogen (N) in order to ensure maximum dry matter (DM) yields. This practice also increases the N content of herbage. This study was conducted to determine whether differences in the nitrogen (N) content of Italian ryegrass would have an effect on the performance of South African Mutton Merino lambs. Fertilizer levels of 100, 200, 400, 600 or 800 kg N/ha were applied to the pastures in order to produce herbage containing varying concentrations of N. Nitrogen fertilization increased the total N and nitrate-N in the plant material and decreased non-structural carbohydrate concentrations. An increase in rumen ammonia-N concentration with increasing pasture N concentration was observed in twelve and four-month-old lambs. A quadratic relationship was found to exist between the N content of ryegrass and DM intake for twelve-month-old lambs, and a negative linear relationship was observed for four-month-old lambs. A quadratic relationship was observed between the N content of ryegrass and average daily gain for lambs of both age groups. The equations derived in this study illustrate the potentially negative effects of high concentrations of N and nitrate-N in Italian ryegrass on intake and growth rate of lambs.

A Novel Approach to Grass–Legume Management

“…Increasing the levels of N fertilizer application caused an increase in mean NO 3 -N concentration of the herbage (de Villiers and van Ryssen, 2001). This, however, did not surpass the safe limit blood levels of 57.0 to 60.0 mg 100 ml -1 for ruminants (de Villiers and van Ryssen, 2001). …”

“…Thus, growing the late maturing variety such as Marshall annual ryegrass will allow producers to extend the production of high quality forage into late spring (Redfearn et al, 2002). Increasing the levels of N fertilizer application caused an increase in mean NO 3 -N concentration of the herbage (de Villiers and van Ryssen, 2001). This, however, did not surpass the safe limit blood levels of 57.0 to 60.0 mg 100 ml -1 for ruminants (de Villiers and van Ryssen, 2001).…”

Forage yield and quality response of annual ryegrass (Lolium multiflorum) to different water and nitrogen levels

“…It is grown by commercial farmers for intensive dairy, lamb and beef production (de Villiers and van Ryssen 2001). It is best adapted to areas with long seasons of cool, moist weather, and well drained soils but can be tolerant to a wide range of soils and climates.…”

The hunt for plant viruses in South Africa: The early days

“…Annual ryegrass (Lolium multiflorum) is an important forage crop in many parts of the world including South Africa, where it is grown as a cool season pasture species under irrigation by commercial farmers for intensive dairy, lamb and beef production. 32 It is mainly cultivated in Gauteng, North West, Free State and Kwa-Zulu-Natal Provinces.…”