Maternal ingestion of locoweed

• Published in: Small ruminant research 2006-09, Vol.65 (1), p.51-63
• Main Authors: Pfister, J.A., Astorga, J.B., Panter, K.E., Stegelmeier, B.L., Molyneux, R.J.
• Format: Article
• Language: English
• Subjects: Astragalus; Neonate behaviour; Oxytropis sericea; Sheep; Swainsonine; Toxic plants
• ISSN: 0921-4488; 1879-0941
• DOI: 10.1016/j.smallrumres.2005.05.027

This study investigated whether exposure of ewes to locoweed ( Oxytropis sericea; Leguminosae) during gestation would affect ewe behaviour during parturition, ewe–lamb bonding and related behaviours postpartum, and maternal responsiveness of ewes to alien and own lambs. Twenty-nine nulliparous Columbia-Targhee ewes bearing a single fetus were divided into two feeding treatments: (1) locoweed ( L, n = 15), fed as a 10% locoweed pellet at 3 kg/day from day 100 to 130 of gestation, or (2) controls ( C, n = 14) fed 3 kg/day of alfalfa hay. Lamb birth weights were reduced about 25% ( P < 0.001) from maternal locoweed ingestion. There was a distinct lack of maternal–infant bonding due to locoweed intoxication of lambs. Only 1 lamb born to L ewes was able to nurse without assistance within 120 min. Lambs born to L ewes took longer to stand ( P < 0.05), to initiate teat-seeking behaviour ( P < 0.03), and to suckle ( P < 0.0007). The behavioural toxicosis did not persist in lambs, as behavioural anomalies largely disappeared within 10 days following parturition. Locoweed-intoxicated ewes in general had an increased propensity ( P < 0.1) for locomotor activity, notably during fetal expulsion, and longer fetal expulsion times ( P < 0.1). There were few behavioural differences induced by locoweed up to 30 min postpartum, when L ewes became inattentive to lambs ( P < 0.1). After the first (human assisted) suckling bout, L ewes were attentive toward both their own and alien lambs. Both L and C dams were equally aggressive toward alien lambs. These results indicate that lamb survival after maternal locoweed exposure will depend greatly on human intervention. If locoweed-exposed lambs survive the first 24–48 h after birth, then the prognosis for survival improves greatly.