Fachbereich Veterinärmedizin



    Untersuchungen zur Schwefelversorgung von Milchkühen (2015)

    Wall, Kirstin (WE 18)
    Berlin: Mensch und Buch Verlag, 2015 — V, II, 150 Seiten
    ISBN: 978-3-86387-682-1
    URL (Volltext): http://www.diss.fu-berlin.de/diss/receive/FUDISS_thesis_000000101345
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    Abstract / Zusammenfassung

    The aim of this study was to investigate and assess the dietary sulfur status in dairy cows and to develop a recommendation for the evaluation of the sulfur status. The analyzed data was collected between 2006 and 2012 by the department of herd-health of the Clinic for Ruminants and Swine at the Free University of Berlin. The samples originated from Brandenburg, Mecklenburg-Vorpommern, Lower Saxony, Saxony, Saxony-Anhalt and Thuringia. Even though the industry reduced its emission of sulfur dioxide immensely during recent decades, this study shows a trend of increasing dietary sulfur concentration. At the beginning of the evaluation period the dietary sulfur concentrations were very low, as expected, reaching only a sulfur concentration which is considered undersupplied. By the end of the evaluation period the sulfur concentrations were still too low. However, they continuously increased year to year, reaching up to the lowest range of the adequate status. The use of anionic rations nearly doubles the concentration of sulfur in the diet compared to rations without acid salts. Thus the dietary sulfur concentration of these cows was in the high range of the sulfur status pointing out an increasing tendency as well. The very small range of the adequate sulfur status makes it almost impossible to meet the requirements precisely. When defining a new feeding ration it should be considered that the digestibility and the availability of sulfur depends on a variety of factors, such as the form and source of sulfur and the relation of N:S in the food ration. Additionally, there are interactions to feed additives, such as trace elements. Published studies underline that even very similar field experiments often lead to different monitoring results. Therefore, it has been proposed to define a more accurate availability of the different sulfur forms and sources. The definition of the maximally tolerable and toxic sulfur amounts must be adjusted and result in new and more appropriate feeding recommendations. Further detailed research is needed regarding this matter. Statistically significant correlations between the dietary undersupply of sulfur and a number of diseases have been determined in this study. These include increasing incidences of ovarian cysts, retention of the afterbirth, displacement of the abomasum, metabolic disorder, digestive disorder, ruminal acidosis as well as hoof and limb disease. This is particularly noticeable in dairy cows that have not been fed an anionic ration. These obvious results underline the importance of the dietary sulfur supply. Sulfur forms a significant part in the health of dairy cows. More attention has to be paid to this neglected element on formulating feeding rations. In terms of monitoring the dietary sulfur status of dairy cows this study analyzed the total sulfur amount of blood (whole blood, serum, plasma), hair and urine samples. Especially noteworthy is that only the sulfur concentration of the urine samples is significantly connected to the dietary sulfur concentration. The sulfur concentrations in serum, plasma, whole blood and hair do not show a significant interaction with the dietary sulfur concentration. Therefore it is proposed to evaluate the dietary sulfur status by analyzing the sulfur concentration of the urine. The status of the urine allows conclusions regarding both the individual animal as well as the state of the herd. Some authors suggest measuring the sulfur concentration in rumen fluid or gas, but extracting urine is the simpler and quicker method. All tested mediums reflect the sulfur status over different time periods. While the urine can be used as a short-term parameter, blood can be used to establish the medium-term supply and hair reflects the long-term supply. The following table shows the recommended reference values to evaluate the sulfur status of dairy cows.

    Medium Reference values
    Serum (mg/l) 750-1200
    Plasma (mg/l) 850-1400
    Whole blood (mg/l) 1000-1800
    Hair (mg/kg) 30000-53000
    Urine (mg/l) 350-2200