Latent acidosis in the dairy cow

Abstract

Today, latent acidosis is a cause of the zootechnical inefficacy of the established food rations and for this reason has become one of the major preoccupations in modern nutrition of high potential ruminants. Dairy cows are required to treat large quantities of rapidly fermentable organic matter, which imperils the control of ruminal acidity and eventually the animal’s homeostasis. The risk factors are now well known. The level of ingestion, rapidly digestible carbohydrates and the excessive chopping of corn silage figure amongst these factors. Even though it is not always desirable to reduce the amount of food ingested, the risks can be reduced by limiting the intake levels of rapidly degradable carbohydrates (wheat, barley, pulp) and by surveying the physical presentation of the fodder. Unfortunately, no system yet exists that allows to precisely rationalise the food ration as a function of these factors. The intraoptimal rations can be protected by distributing buffers. More recently, it has appeared that cation enrichment and protein intake level are also factors that protect the rations. The management of the risk of appearance of latent acidosis should be preventive and should include a better overall balance of the ration. In the absence of a reliable system that predicts the zones at risk, it is preferable not to incorporate more than 20% of rapidly degradable carbohydrates in the ration, especially if the electrolytic balance is low, which is the case for wheat, barley and citrus pulp. It is also important to make sure that the forage sent to the feeding trough is not chopped too finely. The rations can also be protected by including buffering substances at a concentration of 1% DM and/or by including cations that give an electrolytic balance close to 200mEq/kg MS as well as maintain a level of protein intake close to 100g PDIE/UFL. These precautions are more efficient in managing the excess of acidity than that of hay in the ration. It is no longer necessary to include degradable proteins in excess, which will just only increase the amount of nitrogen in waste.