Influence of particle size of grass silage fed in TMR on passage rate and digesta volume in high-yielding dairy cows
- Publication Type
- Contribution to conference
- Authors
- Junck, B., Tafaj, M., Zebeli, Q., Steingaß, H. and Drochner, W.
- Year of publication
- 2005
- Published in
- Berichte der Gesellschaft für Ernährungsphysiologie
- Editor
- H. Martens
- Pubisher
- DLG-Verlags-GmbH , Frankfurt/M
- Series/labeling
- Proc. Soc. Nutr. Physiol.
- Page (from - to)
- 139
- Conference location
- Stuttgart-Hohenheim
- Conference date
- 08.-10.03.2005
- Keywords
- dairy cow, digesta volume, grass silage, Hochleistungskuh, TMR
Objective: Structural effectiveness of total mixed rations (TMR) in the feeding of high-yielding dairy cows is strongly influenced by the forage particle size. This study investigated the effects of the particle size (PL) of grass silage (GS) offered as TMR on passage rate and ruminal digesta volume. Methods: The experiment was carried out with 4 rumen-cannulated Holstein cows (BW 640kg) in the early lactation (36kg milk/d). GS (31.3% DM, 46.5% NDF in DM, degradation rate of DM [DM-kd] 0.087) that was harvested at 25mm theoretical length of cut provided the coarse silage for the diets. Middle and finely chopped silages were obtained by re-cutting the ensiled GS in a self-propelled forage harvester at 1 lmm and 5.5mm, respectively. The GS of three levels of PL was fed as TMR (45.9% DM, 15.1% CP and 35% NDF in DM, DM-kd 0.105) with a concentrate (C) mixture (19.3% NDF, DM-kd 0.127) and coarse hay (H) (GS:H:C = 45:5:50). Cows were fed ad lib twice daily at 0800 and 1600 h. After an adaptation period of 1 ld, Yb-NDF (145g/animal) and LiCo-EDTA (15g/animal via rumen fistula) were used as pulse dose for determination of solid and fluid digesta passage rate, respectively. Faecal samples were collected over 144h after marker dosage and concentrations of Yb and Co in dried faeces were measured by AAS. Passage parameters were estimated using a two-compartmental model (Moore et al., 1992). On d 22 and 25 the rumen content was emptied 2h after the morning feeding and the amount of solid and bailable liquids was recorded (Robinson et al., 1987). The PL effects were tested (Mixed Proc) and the significance of differences was proved by least signif. difference (LSD). The effect of lactation day (Ld) was also considered.