Conditioning and aversion to toxic Solanum bonariense ("naranjillo") leaves in calves

Abstract

ABSTRACT: Solanum bonariense is a perennial poisonous shrub that induces cerebellar cortical degeneration when eaten by cattle. The aim of this research was to outline a protocol to induce a conditioned aversion to this plant. During the pre-conditioning period ten calves (126±12kg BW) were maintained at half of their normal energy intake with lucerne hay and water ad libitum, to stimulate consumption of S. bonariense. Every two days they were offered 100g ofS. bonariense leaves for 5 minutes. Calves began eating the target plant on day 10 and consumed all the plant material on day 12. The conditioning period began after each calf consumed the entire amount of S. bonariense for three consecutive sessions. Five animals were randomly selected for conditioning, and after ingestion ofS. bonariense they were dosed by oral gavage with lithium chloride (LiCl) at 200mg kg-1 BW (treated group), while the other five received a similar volume of water by oral gavage (control group). After 2 doses of LiCl the treated group ate no S. bonariense while the control group consumed the entire 100g. We confirmed that LiCl is a powerful tool to induce conditioned aversions against S. bonariense in calves, which persists for at least 3 months.