1. Effects of defoliation (cutting or grazing on pasture yield

2. Factors Cutting frequency Cutting intensity Timing Selection (grazed pastures) severity

3. Effects of cutting frequency on DM yield and protein content of Napier Cutting interval (wks) DM Yield (t/ha) Protein content (%) Protein Yield (t/ha) 3 (17)10.819.42.1 4 (13)14.414.52.1 6 (9)18.712.12.3 7 (7.4)19.011.02.1

4. Conclusion Short cutting interval – low yield, but high quality Long cutting interval – high yield but low quality

7. Suitable cutting interval Cutting interval giving moderately high yield with good quality Average 4-6 weeks Legumes – needs longer interval

8. Why does yield decline with frequent cutting? Reduction in soluble carbohydrate for regrowth Reduction in Leaf Area Index (LAI) for photosynthesis Retardation of root growth

9. Measurement of Pasture Yield Two types : Dry matter on offer – yield at any one time Production Yield – yield over a unit time

10. Dry matter on offer Use sample quadrats (0.5 m x 0.5 m; 1m x 0.5 m) Place quadrats randomly in field Cut all vegetation in quadrat Weigh fresh and dry all or sub sample in oven at 65 o C for 48 hours Weigh dried sample Convert average weight to kg/ha