Incidence of complemented feed on false positive results with Delvotest SP(R) for detection of antibiotics in milk.

The study described in this paper was performed to show the influence of fe ed complemented by minerals, oligo-elements and vitamins (CMV) on the resul ts of Delvotest SP(R). Three trials were developed. In the first trial, a g roup of 13 dairy cows was divided into two subgroups of six and seven cows, receiving the first one a reed basis without CMV, the second one, the same feed basis added of 100 g CMV per day. During the second trial, the dose o f CMV was doubled for the last seven cows. During the third trial, all the 8 cows were grazing. The four cows of the rest group received 200 g of CMV per day. The two homogeneous groups of cows (somatic cells, number of lacta tions) were followed for detection of inhibitors in milk using Delvotest SP (R). The test gave positive results with milk from complemented cows during the first and the second trials. All results were negative during the thir d trial. Feed appears to be a factor that may give false positive results i n the determination of antibiotics in milli with Delvotest SP(R). (C) Inra/ Elsevier, Paris.