A quantitative approach to assess fibre adequacy based on physiological responses and diet characteristics in high-yielding dairy cows fed TMR ad-libitum.
- Publication Type
- Contribution to conference
- Authors
- Zebeli Q., Tafaj M., Drochner W.
- Year of publication
- 2007
- Published in
- Proc. Soc. Nutr. Physiol., , Vol. p.
- Editor
- Gesellschaft für Ernährungsphysiologie
- Pubisher
- DLG-Verlags-GmbH , Frankfurt/M
- Series/labeling
- Proc. Soc. Nutr. Physiol.
- Page (from - to)
- 63
- Conference name
- 61. Tagung
- Conference location
- Göttingen
- Conference date
- 06.-08.03.2007
- Keywords
- Milchkuhfütterung, TMR-Fütterung
Introduction: Finding an optimum of dietary fibre in high-yielding dairy cows is important to assure normal rumen function, and hence optimise digestion, animal health and production. Yet, fibre adequacy is difficult to predict from feed tables. We used a statistical approach to develop a physiologically-based, easy-to-use model to optimise dietary fibre in high-yielding dairy cows in early lactation, based on physiological responses to physical and chemical characteristics of the diet. Results: This study showed that ruminal pH is the physiological response variable most sensible to the changes of physical or chemical characteristics of the ration in early lactation, indicating that ruminal pH is more important than response of chewing activity or milk fat content. Thus, ruminal pH quadratically increased with elevating the content of peNDF>1.18 in the ration (see Figure), while a linear decline was observed with increasing RDS amount in TMR [pH = 6.34 - 0.02*RDS (% diet); R2 = 0.47; RMSE = 0.11 pH-units]. When both peNDF>1.18 and RDS were tested in a model, the estimation of ruminal pH further increased (R2 = 0.75, RMSE = 0.11), indicating an interaction between peNDF>1.18 and RDS content of the diet. Conclusion: This quantitative approach revealed that accounting for dietary peNDF>1.18 is a more efficient procedure to assess fiber adequacy (through pH measurements) in high-yielding dairy cows than simply relying on dietary NDF or forage NDF. Moreover, this study showed that the intake of rapidly fermentable carbohydrates is more important than total dietary NFC to avoid ruminal acidosis