The toxic effects of mature flatpea (Lathyrus sylvestris L cv Lathco) on sheep

The toxic effects of mature, seed-bearing flatpea (Lathyrus sylvestris L cv Lathco) hay on sheep was studied in a feeding trial with 25 adult ewes. Five ewes were barren; 20 were in the last 10 w of pregnancy. The ewes were blocked by weight and reproductive status for assignment to treatment groups. Four groups of 5 ewes each were allotted to 1 of the following diets: 0% (controls), 35.0%, 52.5% or 70.0% flatpea (FP); and 1 group of 5 ewes was allotted to a diet of increasing levels of 17.5, 35.0, 52.5 and 70.0% FP. Flatpea hay was harvested in the mature, seed-bearing stage, pelleted, reground and incorporated into a basal (control) diet of 30% corn + 70% alfalfa by substitution of an appropriate amount of FP for alfalfa. The resulting diets were fed for up to 42 days. The toxic nature of FP was expressed by the following dose-related responses: Fluctuating reductions in feed intake upon initiation of diets containing 35% FP and above; occurrence of a potentially fatal, acute central nervous system syndrome at FP levels as low as 35%; and reduced weight gain at FP levels of 52.5% and above. A wasting condition was observed in 1 ewe fed 52.5% FP. Four of 5 ewes and 1 lamb fed increasing levels of FP developed acute poisoning. One of these ewes developed acute neurotoxicosis when consuming 52.5% FP; 3 other ewes and 1 40-d-old orphaned lamb developed neurotoxicosis upon raising the FP level to 70.0%.(ABSTRACT TRUNCATED AT 250 WORDS)