A SURVEY OF MATERNAL COPPER STATUS AND FETAL TISSUE COPPER CONCENTRATIONS IN SASKATCHEWAN BOVINE

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Abstract
Copper (Cu) status of cattle raised in different soil zones of Saskatchewan was examined with emphasis on the relation between liver Cu concentration in pregnant cows, stage of pregnancy and fetal liver Cu status. Whole fetuses and livers from adult animals were obtained during routine slaughter operation at a local packing plant. Twenty percent of steers, 54% of pregnant cows, 52% of heifers and 77% of nonpregnant cows had liver Cu levels less than 25 mg kg−1 dry matter (DM). Hypocuprosis was most marked in cattle originating from northern regions of Saskatchewan. Fetal liver Cu concentration depended on the dam liver Cu concentration and on stage of pregnancy and could be represented as: Fetal liver Cu concentration (mg kg−1 DM) = 217.5 + 0.023 [(age of fetus (days) × dam liver Cu concentraiton (mg kg−1 DM)]. During gestation the level of Cu progressively increased in the fetal liver and decreased in maternal liver. Liver Cu levels of fetuses from dams with liver Cu greater than 25 mg kg−1 DM were higher (P < 0.05) than those in fetuses from dams with liver Cu levels lower than 25 mg kg−1 DM. Dam liver Cu status did not influence fetal liver, kidney, heart and brain weights or the Cu concentration of fetal kidney, heart or brain. The magnitude of hypocuprosis in cattle in Saskatchewan is extensive and emphasizes the importance of adequate Cu nutrition in pregnant cattle with respect to maintaining acceptable fetal Cu status. Key words: Copper deficiency, Saskatchewan, soil zones, cattle, pregnancy, fetus