Grassroots Vol 21 No 4 - Page 10

FEATURE

To cut or not to cut ? How should farmers manage grazing cycles of annual ryegrass-Lolium multiflorum PN Rakau

Current Address : Agricultural Research Council , Cedara , Animal Production Institute , Forage Breeding , P . O . Box 1055 , Hilton 3245 , KwaZulu Natal , South Africa . E-mail Address : RakauP @ arc . agric . za

Annual Ryegrass – Lolium multiflorum is a tufted grass mostly planted under irrigation , and is relatively tolerant to different conditions in South Africa . There are two types of annual ryegrass , namely ; the Italian and Westerwolds types . Italian types become reproductive with a significant cold period and have a long growing season (+/ - 12 months ) when planted in autumn , and even longer (+/ - 18 months ) when planted in spring . Autumn planting can yield between 14 to 20 t DM / ha / season and three grazing cycles / season . Most Italian types have the ability to persist . Westerwolds types do not require a prolonged cold period to reach a productive stage and will produce better dry matter yield in mid-winter and spring . Therefore , it is also known as a “ quick starter ”. It will become reproductive in October when planting it in autumn .

The Agricultural Research Council ( ARC ) Animal production ( AP ) forage breeding unit based at Cedara has bred 27 registered cultivars of both Italian and Westerwold ryegrass since 1993 and were granted Plant Breeders Rights ( PBRs ).
Two new Italian ryegrass cultivars , both tetraploid and diploid , will be released in the near future .
Due to annual ryegrass ’ s quick establishment , it can be utilized 8 to 10 weeks after planting when planted in autumn . The first grazing cycle should take place as soon as canopy cover becomes dense to prevent the uprooting of the plant by animals during grazing . There are three ways or indicators that can be used to determine if the ryegrass plant is ready for grazing , namely :
• Three-leave stage : ryegrass plants will maintain only three leaves . If the fourth leaf comes out , the first leaf will die . This will happen as long as the grass is not cut or grazed .
• Grazing interval of 28 to 30 days : most of the ryegrass cultivars take about 28 to 30 days to reach threeleave stage .
• Plant height : ryegrass plant can reach a height of 40 to 60 cm before lodging .
Farmers will have more choice on which method or indicator to use when managing their ryegrass grazing cycles . All these three methods are effective and related to each other and produce almost the same results . The plant height method can be applied for the first grazing cycle after planting .
The 28 to 30 days grazing interval method can be applied during winter and early spring because most of the ryegrass cultivars are at their peak growing stages . Lastly , the three-leave stage method can be applied during late spring and summer if the planting date was in autumn .
This information will help to improve the management of grazing cycles and the performance of a ryegrass field to increase the performance of dairy animals . Farmers will reduce the high cost of supplement feeds during the winter season if ryegrass grazing cycles are improved .
Acknowledgements : The Agricultural Research Council ( Cedara , Animal Production , Range and Forage ) is gratefully acknowledged for funding the project and institutional support .
Figure 1 . The plant height of annual ryegrass at ARC-Cedara fields is between 50 and 60 cm .
Figure 2 . The three-leave stage of ryegrass .
Figure 3 . The annual ryegrass trial at ARC Cedara Research station , Kwa- Zulu Natal , South Africa . The trial was planted on March 2021 and harvested monthly or at 28-day intervals .
09 Grassroots Vol 21 No 4 December 2021