The effectiveness of copper oxide wire particles as an anthelmintic in pregnant ewes and safety to offspring

The objective of the experiment was to determine the effectiveness of copper oxide wire particles (COWP) in pregnant ewes and safety to lambs. COWP have been used recently as an anthelmintic in small ruminants to overcome problems associated with nematode resistance to chemical dewormers. Doses of COWP (<= 4 g) have been used in lambs without clinical signs of copper toxicity. Use in pregnant ewes has not been examined. Mature Katahdin ewes were administered 0 (n = 14), 2 (n = 15), or 4 (n = 15) g of COWP 33 +/- 1.6 days before lambing in late March 2004. Fecal egg counts (FEC) and blood packed cell volume (PCV) were determined between Days 0 (day of COWP administration) and 35. Lambs were weighed within 24 It after birth, at 30 and 60 days of age, and in mid-September (similar to 120 days of age). Blood was collected from lambs within 24 It after birth and at 30 days of age for determination of the activity of the liver enzyme, aspartate aminotransferase (AST) in plasma. Within 7 days after COWP administration, FEC decreased by 1308 and 511 eggs/g (epg) in the 2 and 4 g groups, respectively, compared with an increase of 996 epg in the control group (P < 0.02). PCV was similar among groups between Days 0 and 35. Lamb plasma AST activity at birth increased with increasing dose of COWP in dams (P < 0.001). Plasma AST activity at 30 days of age was similar for lambs from ewes treated with 0 and 2 g COWP, but was slightly greater in lambs from ewes treated with 4 g COWP (P < 0.02). Birth weights decreased with increasing COWP (P < 0.003). By 30 (COWP x birth type, P < 0.02) and 60 (COWP x birth type, P < 0.02) days of age, weight of multiple-born lambs decreased with increasing COWP, while weight of single-born lambs was similar among treatments. In mid-September (similar to 120 days of age) weights of multiple-born lambs from ewes treated with 4 g COWP tended to be lightest compared with lambs from ewes treated with 0 or 2 g COWP or single-born lambs (P < 0.09). Lamb survival to 30, 60, or 120 days of age was not affected by COWP treatment to ewes. Administration of 4 g COWP to late pregnant ewes may negatively impact multiple-born offspring, but the 2 g appears to be safe for production. (c) 2005 Elsevier B.V. All rights reserved.