Effects of either sodium selenite or Se yeast (Sc CNCM I-3060) supplementation on selenium status and milk characteristics in dairy cows

Abstract This study aimed to determine the effects of either dietary Se source or dose on dairy cow Se status, milk yield and subsequent milk characteristics. Forty lactating cows, offered the same basal diet, were blocked by DIM, milk yield and parity and then randomly allocated to 1 of 5 dietary treatments: negative control (CTRL; 0.098 mg of Se kg − 1 DM), 2 Se yeast supplementation (SY03 and SY05, containing 0.31 and 0.50 mg of total Se kg − 1 DM, respectively), and 2 sodium selenite supplementation (SS03 and SS05, containing 0.31 and 0.50 mg of total Se kg − 1 DM, respectively). During the trial (lasted 140 d), whole blood, plasma, and milk were analyzed for total Se, and whole blood for glutathione peroxidase activity. The proportion of total Se as selenomethionine (SeMet) or selenocysteine (SeCys) in whole blood and milk samples was also determined. Milk constituent, SCC, technological properties and keeping quality were measured on milk samples. Neither source nor dose was seen to affect milk yield, SCC, or milk characteristics. Glutathione peroxidase activity was greater ( P P P P P