Effect of either sodium selenite or Se-yeast supplementation on selenium status and milk characteristics in dairy goats.

Abstract This study aimed to determine the effects of dietary Se source on goat's milk and blood Se status, and its subsequent effects on a number of milk characteristics. Ninety lactating dairy goats fed the same basal diet were randomly allocated to 1 of 3 dietary treatments: negative control (CTRL), containing background Se only (dietary concentration of 0.13 mg Se kg −1 DM); selenium yeast (SY) as the Se supplement (0.26 mg Se head −1  d −1 of Se–yeast individually offered); sodium selenite (SS) as the Se supplement (0.26 mg head −1  d −1 of sodium selenite individually offered). The period of supplementation was 112 d. Jugular venous blood samples (before morning meal) and milk samples (a.m. milking) were taken from 10 goats/treatment on d 0, 28, 56, 84 and 112, and milk yields recorded. On d 84 three Italian fresh cheeses were manufactured from bulk milk taken from each treatment. Selenium content of whole blood, plasma, milk and cheese was determined and erythrocyte glutathione peroxidase (GPX-1) activity was also measured. The proportion of Se incorporated as selenomethionine (SeMet) or selenocysteine (SeCys) in pooled whole blood samples was determined on d 0, 56, and 112. Milk samples were analysed for fat, protein, lactose, somatic cell count, thiocyanate and lactoperoxidase activity. Keeping quality of pasteurized milk was measured using pH, clot on boiling and alcohol stability tests. Data were analysed as repeated measures. Both Se sources, when compared to CTRL, increased GPX-1 activity ( P P P P