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 studied over a 7-month period after parenteral supplementation using Cu heptonate and barium (Ba) selenate in 44 8-month-old South African (SA) Mutton Merino wethers. Responses in plasma Cu and blood Se concentrations, as well as fecundity were also measured in a breeding flock of SA Mutton Merino ewes for 3 consecutive years. The effect of maternal supplementation with Cu and Se was assessed in terms of biochemical parameters and production responses in 654 lambs produced by these ewes. Parenteral treatments with Cu and Se raised liver and kidney concentrations (P ≤ 0,05) for up to 7 months in wethers under conditions where liver Cu and Se respectively declined to concentrations below 30 mg/kg DM and 300 μg/kg dry matter (DM) in spring. Plasma Cu concentrations of breeding ewes which received Cu heptonate were increased (P ≤ 0,05) by 18% relative to the control group in which concentrations declined to 91 ug/dl during late pregnancy. Blood Se concentrations of control ewes exceeded 200 ng/ml, and were unaffected by parenteral Se supplementation. Survival of progeny of Cu heptonate treated ewes tended (P ≤ 0,10) to be improved by 13% (0,68 vs 0,60). This tendency was accompanied by generally higher (P ≤ 0,10) plasma Cu concentrations 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 ≤ 0,05) liver Cu concentrations than control group contemporaries. Maternal supplementation with Ba selenate enhanced (P ≤ 0,05) lamb live mass at 8 weeks by 7.4% relative to control group lambs, but did not affect weaning mass. Lambs born to dams receiving Ba selenate and which died prior to weaning, had 20% higher (P ≤ 0,05) liver Se concentrations than control group lambs. Parenteral treatment of sheep with Ba selenate and Cu heptonate was effective in improving liver Cu and Se concentrations of experimental animals. This led to an economic benefit in the case of the response in lamb survival to Cu supplementation. Under more demanding conditions in terms of Cu and Se availability, marked economic benefits are expected after parenteral supplementation.