Bitterweed Ingestion May Impact Reproductive Potential in Rambouillet Lambs and Ewes
Bitterweed (Hymenoxys odorata) is a cool season annual forb that causes toxicosis in sheep. However, limited knowledge is available on bitterweed’s effect on reproduction in sheep. Trial 1 assessed the effect of bitterweed on fetal development. Eight mature Rambouillet ewes were dosed with ground bitterweed and 8 did not receive bitterweed. Fetal survival and birth weights were recorded. For Trial 2, 14 Rambouillet ewe lambs were divided into two treatments with half dosed with bitterweed with hormonal changes recorded to determine the impact on reproductive development. Trial 3 determined if bitterweed affected sperm production in Rambouillet ram lambs. Twenty-five rams were allocated into either the bitterweed treatment or the control. For all trials, treatments were dosed with ground bitterweed (0.2% BW) mixed in distilled water. Intake of a novel food was paired with bitterweed dosing to assess toxicosis. Serum metabolite concentrations were monitored to assess soft tissue damage from toxicosis. Bitterweed toxicosis reduced intake and elevated serum metabolite concentrations in all three trials. Bitterweed ingestion did not affect fetal survival, vigor or birth weights, but did impact ewe lamb reproductive development as evident from the lower (P < 0.05) luteinizing hormone levels. In Trial 3, bitterweed ingestion did not impact sperm production.