Calculs de ration et évaluation du risque d'acidose

Abstract

Rumen acidosis raises specific issues in intensive farming. It is therefore desirable to have indicators allowing the assessment of the risk of acidosis in diet formulation. To establish theses criterion, several data bases gathered on bovines were analyzed with statistical meta-analyses approaches. This process allows determining prediction equations of mean rumen pH value from various types of measurements. Certain criterion, relevant but difficult to measure on farm, mainly concern the units of research. (chewing index, starch digested into the rumen). Other parameters can be determined in commercial farms from the analysis of the distributed rations. This is for instance the case of the proportion of concentrate in the ration, or better, the content of degradable DM of the ration or NDF resulting from long forages within the DM of the ration which are today easily calculable criteria starting from feed tables. The distinction between ruminal and metabolic acidoses was also considered in this work. For each item the pH value of 6.2 was chosen as a threshold under which the risk of acidosis is becoming a concern. From the nine criterion selected, a simple grid of evaluation was built to assess the risk of acidosis by distinguishing in a simple way, for each criterion, the thresholds and the situations at risk. This grid can be easily added to the computation software to allow an objective evaluation of the risk of acidosis based on the values of the criteria.