[Selection of cows for control of the metabolic state in the herd by biochemical blood analyses]

Four consecutive biochemical analyses (July and November 1975 and July and November 1976) of the blood serum were carried out of 100 cows on one farm and 50 cows on another farm. The study made use of data on the inorganic phosphorus content. The test cows of farm I were divided into two groups -- A, consisting of 50 animals of two entire subgroups in one barn, and B, consisting of 50 animals proportionately distributed by subgroups in the remaining four barns. It was established that the proper selection of the control cows was essential as demonstrated by the dependable differences between the level of inorganic phosphorus in the serum of the animals of both groups. The cows had to be equated in terms of productivity and distributed proportionally in the groups of all attendants. The test cows of farm II were likewise divided into two groups of 25 animals each. The changes were followed up in the content of inorganic phosphorus in the two possible variants -- with the successive investigation either of two different groups of animals or individually of one and the same animals. It was demonstrated that the study of one and the same animals individually yielded more precise information on the status of the herd and made it possible to follow up more accurately the changes that had taken place in the metabolic processes under the effect of external factors. Stated is the diagnostic value of the differences in the index values obtained from two consecutive analyses.