Study of acid-base metabolism in dairy cows under field conditions
Dypvik, Synnove Sverresdotter
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The increased intensity in modern dairy farming enhances the risk of metabolic diseases in a herd. The increased energy demand in the transition period, calls for higher energy density in the diet to prevent negative energy balance. The appropriate BCS around parturition is 3.5. If the cow is to fat it decreases its intake before parturition, this can lead to ketosis and fatty liver syndrome. To prevent Negative energy balance after parturition the dietary intake of concentrate is increased. To quick change in the diet, does not leave time for the rumen to adapt to the high amounts of acids produced from the breakdown of rapidly fermentable carbohydrates. This can lead to the development of ruminal acidosis. Other factors that lead to the development of ruminal acidosis can be stress due to overcrowding and heat. Ruminal acidosis is a widespread herd problem; it’s the gateway to numerous other diseases such as ruminitis followed by liver abcsessation and peritonitis. It’s also closely related to the development of laminitis. It can be diagnosed on base of its clinical signs and by measurement of ruminal and urine pH and by determination of the net acid base excretion concentration of the urine. The use of metabolic profile test is very useful to diagnose metabolic diseases on a herd basis. This test measures different parameters from the urine (NABE and pH) and blood (glucose, BHB, NEFA, AST). These parameters can tell something about the metabolic condition of the herd. In this study samples were taken on to occasions. The first samples showed that the herd was acidic, and that the fresh cows had very high levels of AST, indicating fatty liver syndrome. The cows were overcrowded and were given 4-5kg concentrate daily which is too high, they were not given time to adapt to the high energy diet after parturition. It was recommended that maximum 25% of the daily rations were concentrate, and that the amount of concentrate increases gradually after parturition, hay should be given ad libitum. Stressors should be reduced. The samples taken in November 2008 showed that the herd still was acidic, but it had improved since June. This shows that faulty management and nutrition can be cause of metabolic disease and negative energy balance.