Timothy and Red Clover as Forage for Dairy Production In vitro Degradation Characteristics and Chemical Composition

Hetta, M. 2004. Timothy and red clover as forage for dairy production. Doctoral thesis. ISSN 1401-6249, ISBN 91-576-6481-1. The aim of this thesis was to describe and compare timothy (Phleum pratense L.) and red clover (Trifolium pratense L.) as forage for dairy cattle on the basis of the chemical composition and the in vitro degradation characteristics. Initially the degradation characteristics determined with an in vitro gas production technique and an in vitro filter bag technique were compared. Both techniques were found to be interesting tools for providing relevant degradation parameters for feed evaluation models. Thereafter the degradation characteristics and nutritive value of forages of timothy and red clover were described with recordings of in vitro gas production and chemical analysis. Analysis of the herbage of red clover and timothy showed that red clover contained lower concentrations of neutral detergent fibre (NDF) and had lower degradability of neutral detergent fibre (NDFD) on all harvest occasions. Red clover had on average a higher maximal fractional degradation rate (FDRmax) of the whole forage compared to timothy. The FDRmax for the NDF in red clover was not different from that in timothy. In timothy the components soluble in neutral detergent solution had a higher FDRmax compared to those in red clover. Timothy and red clover were conserved as direct cut silages with the addition of conservation additives. It was found that timothy and red clover herbage responded differently to the silage additives. Silages treated with additives had a shorter time until half of the gas was produced, as well as a shorter time until the maximal fractional degradation rate was reached, indicating a faster in vitro degradation compared to that of untreated silages. The use of additives improved the NDFD in silage with red clover but not that in the silage of pure timothy. The relationships between the feed characteristics and the relative silage intake in dairy cows were evaluated. It was found that the preparation technique for silage samples was important and that wet silage samples had a higher gas production and different kinetics compared to dried samples. It was concluded that chemical analysis in combination with the in vitro gas production technique can be a cost-efficient tool for relative prediction of silage intake based on feed characteristics. The predictions can be used to compose feed rations that will optimize silage intake in relation to milk production and to improve conservation management.