Untersuchung zum Einfluss der DCAB in der Futterration unter besonderer Berücksichtigung von Schwefel und Chlorid auf die Futteraufnahme, Milchleistung und Parameter der Tiergesundheit von Milchkühen

Investigation on the influence of DCAB in feed ration with special consideration of sulfur and chloride on feed intake, milk yield and parameter of animal health of dairy cows

Consumers are demanding more and more GMO-free food. However, due to the feeding of soybean extraction meal to cattle, it is difficult in the dairy production. Soybean extraction meal could be replaced by rapeseed extraction meal. However, significantly higher sulfur contents are found in RES, with otherwise similar composition of bulk element. Thus, the DCAB value of a ration is lowered. The anions sulfur and chloride play a major role in influencing the DCAB. The mineral sulfur can also be utilized by ruminants from an inorganic source by the rumen microbes. The sulfur requirement in lactating cattle (2 g/kg DM) and the toxic range (>4 g/kg DM) are close to each other. Up to a content of 3 g sulfur per kg DM in the ration, sulfur has a positive effect on feed intake and performance.
Chloride is also one of the bulk elements and is closely related to sodium in its metabolism. The requirement of chloride is about 4 g/kg DM in lactating cattle. The toxicity of chloride can be compensated by the body with an adequate supply of drinking water. The DCAB value recommendations during peak lactation in dairy cows are between 200 - 350 meq/kg DM.
During this work, a test feeding with different DCAB values was performed. For this purpose, a dairy cow group in high lactation of 78 cattle was divided into two groups at the LLG Sachsen-Anhalt in Iden. The division was done randomly, based on lactation day, number, milk yield and milk content. The animals were kept in a loose housing with weighing troughs. The study was divided into three series. The basic rations were always the same in both groups during the study, with grass- or corn-based diets. Feed intake and milk yield were recorded daily. Both blood parameters and body condition were recorded at the beginning and end of each study series. Cow signals were recorded once a week, and feces were checked three times per study series.
In the first test series, the study group was additionally fed chloride (Soy-Chlor®). The chloride content of the study group was 7.1 g/kg DM and 12.1 g/kg DM, respectively, compared to a content of 4.4 g/kg DM and 9.2 g/kg DM, respectively, in the control group. Thus, the DCAB was 30 meq/kg DM and 6 meq/kg DM in the study group and 175 meq/kg DM and 166 meq/kg DM in the control group, respectively. In this series of investigations, no significant differences in feed intake were found. However, there was a significant effect over time in the study group, which was greater than in the control group and thus suggests a negative effect because of the changed ration. A similar picture is presented by the milk yield. Again, no significant differences were found between the groups. However, the decrease in milk yield over time was greater in the study group than in the control group.
In the second test series, the DCAB of the study group was raised using sodium bicarbonate (BICAR®Z). The DCAB of the study group was 176 meq/kg DM compared to the control group with a value of 65 meq/kg DM. In this study series, the parameters feed intake and milk yield did not show significant differences.
The third series of tests was divided into three sections. Within the first section, the test group was fed calcium sulfate (CS dihydrate QS). In the second section, the groups were swapped and in the third section, sodium hydrogen carbonate was fed to the study group in addition to calcium sulfate. The sulfur content in the first section was 3.9 g/kg DM and the DCAB value was -5 meq/kg DM. In the second section, a sulfur content of 4g/kg DM was fed to the study group, and the DCAB value was -14 meq/kg DM. Within the third section, 3.9 g/kg DM of sulfur was fed. Due to buffering, the DCAB value was 106 meq/kg DM. The control group was fed a sulfur level of 2.5 - 2.8 g/kg DM consistently. The DCAB value here was 114 - 138 meq/kg DM. Within the whole test series, the study group consumed less dry matter than the control group. The milk yield showed no significant differences between the groups. However, the milk yield of the study group was permanently lower than the control group, which is clearly visible as a tendency. The buffering of the ration did not produce any improvement in feed intake.
In all three series of investigations, the body condition showed an equal increase in both groups. The blood parameters, cow signals as well as the texture showed no significant changes worth mentioning.
In conclusion, DCAB influences feed intake and milk yield in high lactation. The effect of the anion sulfur seems to have an effect on feed intake and milk yield beyond the DCAB value. These statements refer to the range studied in this work, but it is also important to point out that the study duration is quite short.