The Effect of the Czechoslovak Developmental Herbicide Bentazone on Some Parameters of Sheep Health Under the Conditions of Subchronic Intoxication

Veterinarni Medicina 37, 1992, 161-168

A three-month feeding trial was conducted with sheep of the Slovak Merino breed [13-14 months of age, males and females] as a part of the obligatory toxicological tests of the Czechoslovak developmental herbicide bentazone [Research Institute for Chemical Technology, Bratislava]. Partial results are shown describing the action of this herbicide on the overall health of sheep with respect to weight gains, trias values and intrauterine foetus development. The sheep of the first experimental group were fed bentazone as an additive to molasses feed M at a dally rate of 195 mg/kg lwt. [1/10 from LD50], and the sheep of the second group were fed a rate of 97.5 mg/kg lwt. [1/20 from LD50]. No symptoms of the toxic effects of bentazone were observed in the course of the experiment. There were no differences between the experimental and test animals in the dynamics of pulse value changes [Fig. 1], breathing value changes [Fig. 2] and body temperature value changes [Fig. 3] from the beginning till the end of the trial. A slight increase in the pulse and breathing values above the upper reference value observed in the experimental groups in the last two to three weeks of the trial cannot be associated with the bentazone action. This increase reflects the physiological condition of the animals in the given conditions because the identical changes were also found in the control group. We assume that the changes were evoked by the elevated temperature of the external environment due to the fact that the sheep were not sheared. There were not either any differences in the dynamics of liveweight changes [Fig. 4]. The animals of the Ist and control group had the same weight gains. Somewhat lower weight gains against the control were recorded in the IInd experimental group. Given the target herbicide did not cause the growth depression, nor intoxication symptoms manifested in the breathing system and through body temperature changes [the dominant symptoms of acute intoxication], and in spite of the long-time administration of bentazone at the high rates, this herbicide appears as a toxicologically reliable herbicide for sheep. Its nontoxic action is also illustrated by the fact that the continual rate of 97.5 mg/kg lwt. did not influence negatively the intrauterine foetus development in the last month of pregnancy, and the residues in milk did not influence the postnatal development of lambs

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