Tropical Grasslands (2003) Volume 37, 101110
Forage yield, nutritive value, feed intake and digestibility of three grass species as affected by harvest frequency
NGO VAN MAN1 and HANS WIKTORSSON2
1 Department of Animal Nutrition, University of Agriculture and Forestry, Thu Duc, Ho Chi Minh City, Vietnam
2 Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Uppsala, Sweden
experiments on the effects of cutting interval on forage production,
nutritive value, feed intake and digestibility of elephant grass (Eg)
and two guinea grass (Gg) cultivars 280 and I.429, were carried out.
Three grasses harvested at 4 cutting intervals (4, 6, 8 and 10 weeks)
were compared in a split plot design in the production experiment. In
the feed intake and digestibility experiment, 3 grasses and 3 cutting
intervals (4, 6 and 8 weeks) were examined in a 3 x 2 change-over design
with 6 crossbred Holstein heifers.
Forage DM production
increased as length of cutting interval increased and forage quality,
in terms of CP and cell wall concentrations, decreased. The yields of
DM, CP, digestible DM and digestible CP were highest in Gg 280 followed
by Gg I.429 and Eg.
of forage (DM basis) of Eg, Gg 280 and Gg I.429 were 90.4, 104.6 and
94.5 g/kg Lwt0.73, respectively, with no effect of cutting
interval. With the decline in crude protein concentration in older forage,
the CP intake of around 13.4 g/kg Lwt0.73 from the 4-week
cuts declined to about 6.7 g/kg Lwt0.73 in the 8-week cuts.
Digestibility of dry matter and crude protein decreased significantly
as cutting interval increased, with no differences between grass species.
To obtain the
best balance between dry matter yield and forage quality, the optimum
cutting frequency seems to be about 6 weeks. There is a possibility
that this could be extended to 8 weeks for elephant grass.