Indian Journal of Experimental Biology Vol. 42, March 2004, pp.297-302 Effect of supplementary feeding of vitamin Kl on difethialone treated Indian gerbil, Tatera indica Hardwicke in laboratory Vipin Chaudhary & R S Tripathi* All India Coordinated Research Project on Rodent Control, Central Arid Zone Research Institute, Jodhpur 342 003, India and F S Paonia Department of Zoology, Jai Narian Vyas University, Jodhpur 342 001, India Received 25 April 2003; revised 14 November 2003 Two dosages (I and 2 mg/kg) of vitamin K, supplementation for 5 and 15 days were given to Indian gerbil T. illdica fed on difethialone bait (0.0025%) for one day. The results indicated that the lower dosage could not reverse the anticoagulation process, however the period of mortality was considerably increased from 3-9 days (in control) to 5-14 days (5 days supplementation regime). Subsequently when the vitamin K, dosage was doubled and given for 15 days, there was 100% reversal of anticoagulation process and all the test gerbils became normal within a month of poisoning with difethialone bait. Keywords: Anticoagulants, Baits, Difethialone, Gerbils, Plain food, Vitamin K, supplemented food Rodent pest management is largely dependent on usage of toxic rodenticides. Zinc phosphide, an acute rodenticide is being extensively used for the purpose in India and elsewhere J · 3 • Besides being highly toxic to non-targets, zinc phosphide induces bait/poison shyness in a variety of pest rodent species 4 . 5 • With the advent of second-generation single dose anticoagulant rodenticides, the whole concept of rodent pest management has been revolutionized in recent years. They act on the blood vascular system of target animals and inhibit blood coagulation mechanism leading to excessive internal haemorrhage and death of the animals within 3-15 days even after one-day exposure. Moreover, due to their requirement in very small dosages (0.0025-0.005%) in baits, these anticoagulants tend to be relatively safer to non-target species. The anticoagulants and vitamin KJ are known to share the same site of action by blocking the epoxide reductase enzyme system in the blood 6 . Thus process of anticoagulation of blood may be reversed by addition of larger doses of vitamin Kt eO ). Most of the studies on effect of vitamin K J on anticoagulant poisoning have been conducted on larger vertebrates 8 . 9 , however, very little information on this aspect is available on rodents. Considering the bioefficacy of difethialone against major Indian pest *Correspondent author: Phone: 0291-2741689 (0); Fax: 0291-2704706 E-mail: rstripathi@cazri.raj.nic.in rodent species and the safety factor involved through antidoting, the present communication makes a maiden attempts to describe and quantify the effect of supplementary feeding of vitamin KJ on difethialone treated Indian gerbil, Tatera indica Hardwicke in laboratory. Material and Methods The Indian gerbils were captured from crop fields and grasslands near Jodhpur (Lat. 26°18'N Long. 73°01'E). It was ascertained that the captured rodents had no previous experience of feeding on anticoagulant baits. In all 30 healthy adult gerbils of weight range 98-120 g were used in different sets of experiment. The test gerbils were weighed and lodged in iron mesh cages (24"x12"xI2") for acclimatization. During this period the gerbils were fed pearl millet grain and water was available to them ad libitum. Difethialone, a second-generation anticoagulant rodenticide was selected for this study. Five sets containing six experimental gerbils in each were housed in individual cages in the laboratory. Temperature in laboratory was maintained at 28° ±4°C. Four sets acted as treatment, whereas one set was for control/check. Each animal was exposed to difethialone baits (0.0025%) for 24 hI'. During this period no other food was available to the test gerbils, however, tap water was provided ad libitum. Sets I and II - Immediately after exposure of anticoagulant rodenticides, the test animals of these