Malformações, abortos e mortalidade embrionária em ovinos causada pela ingestão de Mimosa tenuiflora (Leguminosae)

Abstract

To determine the teratogenicity of Mimosa tenuiflora, 15 sheep, divided into two groups, were introduced into an area invaded by the plant. Group 1 consisted of six pregnant ewes that were introduced into the experimental area 20 days after mating. Group 2 consisted of nine non pregnant sheep and a ram introduced into the area at the start of the experiment. The experiment began in October 2009, during the dry season, when M. tenuiflora was seeding. During this period the M. tenuiflora plants were pruned to 40cm tall and the branches with leaves and seeds were provided to the experimental sheep in the same area. After prunning M. tenuiflora began to sprout even in the dry season, and the sheep were free to graze the plant. They also received concentrate ration in amount equivalent to 1% of their body weight. After the first rains in mid-January 2010, when the herbaceous layer appeared, the pregnant sheep were confined in stalls, and M. tenuiflora was cut in the field and given to the sheep until the end of the experiment. Every 15 days each sheep was examined by ultrasound to control pregnancy. In Group 1, three sheep aborted single fetuses without malformations. One sheep delivered two lambs, one with hyperflexion of the proximal inter-phalangeal joint of the right forelimb and another without malformations. Another sheep delivered a lamb with a hyperflexion of both hindlimbs in the region of the tarsal-metatarsal joint. Only one sheep delivered a normal lamb. In Group 2, one sheep aborted a fetus without malformations and five delivered normal lambs. Three sheep of this group returned to estrus repeatedly and did not get pregnant during the mating period, suggesting embryonic loss. Thirty two ewes and one ram, that stayed in a paddock neighbor to the experimental paddock and were used as control group, delivered normal lambs. It is concluded that M. tenuiflora cause malformations, embryonic mortality and abortion in sheep.