Milk profiles of selenoamino acids, selenoenzymes, and selenoproteins of peripartal dairy cows fed with different selenium sources.

Objective: This study aimed to investigate the effect of dietary nanoselenium (nanoSe) and sodium selenite (SS) on the concentrations of selenoamino acids, the activities of selenoenzymes, and the mRNA expressions of selenoproteins in the milk of peripartal dairy cows.

Methods: Three diets included a control (basal diet) with background selenium at 0.06 mg/kg and treatments with either SS or nanoSe added at the same selenium concentration of 1.00 mg/kg of diet. A total of 45 dairy cows were randomly allocated to three groups. The feeding trial lasted for 42 days from prenatal 21 days to postnatal 21 days.

Results: NanoSe increased (p<0.05) milk yield compared to the control and SS. In milk, both SS and nanoSe increased (p<0.05) the concentrations of selenium, selenocysteine, and selenomethionine, and the activities of glutathione peroxidase 4, glutathione reductase, thioredoxin reductase, glutathione S-transferase, and iodothyronine deiodinases (type 2 and 3). The nanoSe showed higher (p<0.05) effects on these parameters than SS. Also, dietary nanoSe upregulated (p<0.05) the mRNA expressions of selenoproteins P, W, S, F, M, N, K, O, H, and I in milk compared to the control. For most selenoproteins, there was no difference between SS and nanoSe, only selenoprotein K was higher (p<0.05) in nanoSe than in SS.

Conclusion: In conclusion, dietary nanoSe increased milk yield, milk selenoamino acids and selenoproteins in peripartal dairy cows.