PARENTERAL COPPER AND SELENIUM SUPPLEMENTATION OF SHEEP ON LEGUME-GRASS PASTURES - BIOCHEMICAL AND PRODUCTION RESPONSES IN LAMBS TO MATERNAL TREATMENT

Liver and kidney copper (Cu) and selenium (Se) concentrations were stu died over a 7-month period after parenteral supplementation using Cu h eptonate and barium (Ba) selenate in 44 8-month-old south African (SA) Mutton Merino wethers. Responses in plasma Cu and blood Se concentrat ions, as well as fecundity were also measured in a breeding flock of S A Mutton Merino ewes for 3 consecutives years. The effect of maternal supplementation with Cu and Se was assessed in terms of biochemical pa rameters and production responses in 654 lambs produced by these ewes. Parenteral treatments with Cu and Se raised liver and kidney concentr ations (P less than or equal to 0,05) for up to 7 months in wethers un der conditions where liver Cu and Se respectively declined to concentr ations below 30 mg/kg DM and 300 mu g/kg dry matter (DM) in spring. Pl asma Cu concentrations of breeding ewes which received Cu heptonate we re increased (P less than or equal to 0,05) by 18% relative to the con trol group in which concentrations declined to 91 ug/dl during late pr egnancy. Blood Se concentrations of control ewes exceeded 200 ng/ml, a nd were unaffected by parenteral Se supplementation. Survival of proge ny of Cu heptonate treated ewes tended (P less than or equal to 0,10) to be improved by 13% (0,68 vs 0,60). This tendency was accompanied by generally higher (P less than or equal to 0,10) plasma Cu concentrati ons of these lambs relative to control lambs at 10 - 20 and 45 - 55 d of age. Lambs of Cu supplemented ewes that died prior to weaning, had higher (P less than or equal to 0.05) liver Cu concentrations than con trol group contemporaries. Maternal supplementation with Ba selenate e nhanced (P less than or equal to 0,05) lamb live mass at 8 weeks by 7, 4% relative to control group lambs, but did not affect weaning mass. L ambs born to dams receiving Ba selenate and which died prior to weanin g, had 20% higher (P less than or equal to 0,05) liver Se concentratio ns than control group lambs. Parenteral treatment of sheep with Ba sel enate and Cu heptonate was effective in improving liver Cu and Se conc entrations of experimental animals. This led to an economic benefit in the case of the response in lamb survival to Cu supplementation. Unde r more demanding conditions in terms of Cu and Se availability, marked economic benefits are expected after parenteral supplementation.